Steering wheel hand-off detection method and vehicle

Abstract

This invention provides a method and vehicle for detecting steering wheel hands-off, relating to the field of steering wheel hands-off detection technology, aiming to improve the accuracy of identifying the driver's contact state with the steering wheel under different steering wheel heating scenarios. The method includes: determining the corresponding heating scenario of the steering wheel based on the working state of the steering wheel's heating element and / or multimodal real-time temperature; wherein the multimodal real-time temperature includes the external temperature of the steering wheel, the internal temperature of the steering wheel, and the ambient temperature; the heating element is configured to generate heat in heating mode and act as a capacitance sensing electrode in detection mode; determining a preset capacitance threshold corresponding to the heating scenario based on a threshold determination algorithm; compensating the original capacitance value sensed by the heating element based on a compensation coefficient to determine a target capacitance value; comparing the target capacitance value with the preset capacitance threshold corresponding to the heating scenario, and determining the driver's contact state with the steering wheel based on the comparison result.

Description

Technical Field

[0001] This invention relates to the field of steering wheel hands-off detection technology, specifically to a steering wheel hands-off detection method and vehicle. Background Technology

[0002] As automotive intelligence evolves towards Level 2+ and above, hands-off detection (HOD) has become a core function for ensuring driving safety. Currently, mainstream technologies suffer from blind spots in torque detection, while capacitive solutions, though highly accurate, suffer from hardware redundancy and high costs due to their traditional architecture. To reduce costs, some solutions attempt to eliminate shielding layers or simplify the sensing structure, but this makes the signal highly susceptible to temperature drift across the entire temperature range, airflow disturbances, and electromagnetic interference, significantly reducing detection accuracy and increasing the false positive rate, failing to meet Level 2+ driving safety requirements. These simplified solutions have consistently failed to maintain or improve detection accuracy while reducing hardware costs; this contradiction has become the core bottleneck restricting the mass production and application of HOD technology. Summary of the Invention

[0003] The purpose of this invention is to provide a method and vehicle for detecting when a driver takes their hands off the steering wheel, which aims to accurately identify the driver's contact state with the steering wheel under different heating scenarios by using multimodal temperature compensation and scene adaptive threshold determination.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for detecting when a steering wheel is removed from its hands. The method includes: determining a heating scenario corresponding to the steering wheel based on the operating state of a heating element of the steering wheel and / or multimodal real-time temperature; wherein the multimodal real-time temperature includes the external temperature of the steering wheel, the internal temperature of the steering wheel, and the ambient temperature; the heating element is configured to generate heat in heating mode and to function as a capacitance sensing electrode in detection mode; determining a preset capacitance threshold corresponding to the heating scenario based on a threshold determination algorithm; compensating the original capacitance value sensed by the heating element based on a compensation coefficient to determine a target capacitance value; the compensation coefficient is determined based on the deviation between the multimodal real-time temperature and the corresponding calibration temperature; comparing the target capacitance value with the preset capacitance threshold corresponding to the heating scenario, and determining the contact state between the driver and the steering wheel based on the comparison result.

[0005] Based on the aforementioned technical means, this invention first accurately classifies heating scenarios by combining the working state of the heating element with multimodal real-time temperatures of the steering wheel's external and internal temperatures, as well as ambient temperature. Then, it constructs a compensation coefficient based on the deviation between the multimodal real-time temperature and the calibrated temperature, performing temperature compensation correction on the original capacitance value collected by the heating element to obtain the target capacitance value. Finally, it matches preset capacitance thresholds corresponding to different heating scenarios to determine the driver's contact state. The preset capacitance thresholds for different heating scenarios are determined based on the corresponding threshold determination algorithm for each heating scenario. By distinguishing differentiated heating scenarios and introducing a multi-dimensional temperature deviation compensation mechanism, and dynamically setting preset capacitance thresholds based on the threshold determination algorithm corresponding to each heating scenario, this invention effectively eliminates the interference of temperature fluctuation factors such as high and low temperature environments and steering wheel heating operation on the accuracy of capacitance detection. It avoids the problem of capacitance detection data drift and misjudgment caused by temperature changes, significantly improving the accuracy and stability of steering wheel off-hand detection results and ensuring the reliability of vehicle driving assistance control.

[0006] Furthermore, the compensation coefficients are determined based on the product of the first compensation coefficient and the deviation between the external temperature of the steering wheel and the corresponding calibration temperature, the product of the second compensation coefficient and the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature, and the product of the third compensation coefficient and the deviation between the ambient temperature and the corresponding calibration temperature; wherein, the first compensation coefficient is greater than the second compensation coefficient, and the second compensation coefficient is greater than the third compensation coefficient.

[0007] Based on the aforementioned technical methods, by decomposing the compensation coefficient into the sum of the products of three sub-coefficients corresponding to the deviations in external, internal, and ambient temperatures of the steering wheel, and setting the first compensation sub-coefficient (external temperature) > the second compensation sub-coefficient (internal temperature) > the third compensation sub-coefficient (ambient temperature), the weight differences in the influence of different temperature sources on capacitance detection can be more precisely characterized. The external temperature of the steering wheel directly affects the dielectric properties of the contact surface between the driver's hand and the leather cover, so it is given the highest weight; the internal temperature reflects the influence of the heat conduction of the heating element on the capacitor substrate, so its weight is second; and the ambient temperature, as an indirect interference, has the lowest weight. This hierarchical weighted compensation mechanism significantly improves the physical rationality and calculation accuracy of temperature compensation, making the compensated target capacitance value more realistically reflect the actual contact state.

[0008] Furthermore, the compensation coefficients are determined based on the product of the first compensator coefficient and the deviation between the external temperature of the steering wheel and the corresponding calibrated temperature, the product of the second compensator coefficient and the deviation between the internal temperature of the steering wheel and the corresponding calibrated temperature, the deviation between the third compensator coefficient and the ambient temperature and the corresponding calibrated temperature, and the product of the fourth compensator coefficient and the deviation between the calibrated airflow speed; wherein, the first compensator coefficient is greater than the second compensator coefficient, the second compensator coefficient is greater than the third compensator coefficient, and the third compensator coefficient is greater than the fourth compensator coefficient.

[0009] Based on the aforementioned technical methods, the compensation coefficient is decomposed into the sum of the products of four sub-compensation coefficients corresponding to the external temperature of the steering wheel, the internal temperature of the steering wheel, the ambient temperature, and the ambient airflow speed, respectively, and their respective deviations. Furthermore, the first to fourth sub-compensation coefficients are limited to decreasing sequentially. This ensures that the compensation coefficient prioritizes correcting the external temperature deviation, which has the most significant impact on the steering wheel's feel temperature, followed by the internal temperature, then the ambient temperature, and finally the ambient airflow speed. This layered and orderly compensation method avoids the coarseness of single-temperature compensation and prevents over-sensitivity to secondary factors (such as ambient airflow speed). Therefore, in steering wheel hands-off detection, it can more accurately eliminate the influence of temperature and environmental disturbances on capacitive or pressure sensor signals, improving the robustness and accuracy of hands-off detection while reducing the risk of false or missed detections due to environmental changes.

[0010] Furthermore, the preset capacitance threshold includes a first capacitance threshold and a second capacitance threshold; wherein the first capacitance threshold is greater than the second capacitance threshold; the target capacitance value is compared with the preset capacitance threshold corresponding to the heating scenario, and the contact state between the driver and the steering wheel is determined based on the comparison result, including: if the target capacitance value is greater than or equal to the first capacitance threshold, the contact state is determined to be a gripping state; if the target capacitance value is less than the first capacitance threshold but greater than or equal to the second capacitance threshold, the contact state is determined to be a touching state; if the duration for which the target capacitance value is less than the second capacitance threshold reaches a preset release duration, the contact state is determined to be a release state.

[0011] Based on the aforementioned technical methods, by subdividing the contact state into three levels—gripping, touching, and releasing—and correspondingly setting a first capacitance threshold (high threshold) and a second capacitance threshold (low threshold), the different levels of interaction between the driver and the steering wheel can be more accurately characterized. The gripping state corresponds to a target capacitance value reaching the high threshold, representing effective control; the touching state falls between the two thresholds, representing a light touch or unintentional grip; the releasing state requires a capacitance value below the low threshold and sustained for a preset duration to avoid misjudgments caused by instantaneous noise. This hierarchical judgment combined with duration filtering improves both the resolution of state recognition and enhances anti-interference capabilities.

[0012] Furthermore, the heating scenario corresponding to the steering wheel is determined, including: when the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is greater than the first temperature difference threshold, the heating scenario is determined to be the direct air conditioning blowing scenario; wherein, the threshold determination algorithm corresponding to the direct air conditioning blowing scenario is used to determine the preset capacitor threshold corresponding to the direct air conditioning blowing scenario based on the product of the basic threshold and the first temperature compensation factor, and the first temperature compensation factor is determined based on the deviation between the external temperature of the steering wheel, the ambient temperature and their respective corresponding calibration temperatures.

[0013] Based on the aforementioned technical methods, for scenarios involving direct airflow from the air conditioner (where the heating element is not working, but there is a large temperature difference between the steering wheel exterior and the ambient temperature), a threshold determination algorithm is dynamically adjusted by introducing a first temperature compensation factor (based on the deviation between the external and ambient temperatures and their calibrated temperatures). Since direct airflow from the air conditioner causes abnormal temperature changes on the steering wheel surface, thereby altering the dielectric constant of the capacitance sensing area, failure to compensate will result in capacitance value drift. This solution utilizes real-time temperature difference correction to effectively eliminate interference from air conditioning airflow on the hands-off detection, ensuring accuracy in judgments under special thermal conditions.

[0014] Furthermore, the heating scenario corresponding to the steering wheel is determined as follows: when the heating element is not in heating mode, and the vehicle's overall power-on time is less than or equal to a preset power-on time threshold, and the rate of change of the steering wheel's internal temperature is greater than a second rate of change threshold, the heating scenario is determined to be a cold start power-on scenario; wherein, the threshold determination algorithm corresponding to the cold start power-on scenario is used to determine the preset capacitor threshold corresponding to the cold start power-on scenario based on the product of the basic threshold and the second temperature compensation factor, and the second temperature compensation factor is determined based on the deviation between the steering wheel's internal temperature and the initial steering wheel internal temperature when the vehicle is powered on.

[0015] Based on the aforementioned technical methods, for cold start scenarios (when the vehicle is first powered on and the steering wheel internal temperature changes rapidly), a threshold determination algorithm dynamically adjusts the preset capacitance threshold by introducing a second temperature compensation factor (based on the deviation between the current internal temperature and the initial internal temperature at power-on). During a cold start, the steering wheel internal temperature rapidly rises from a low temperature to ambient temperature, a process that significantly alters the parasitic capacitance characteristics of the heating element (which also acts as the capacitance sensing electrode). This solution utilizes the rate of temperature change to identify this scenario and compensates for the threshold based on the temperature increment, avoiding misjudgments caused by drastic fluctuations in capacitance detection values ​​due to rapid temperature changes, thus improving the reliability of hands-off detection during cold starts.

[0016] Furthermore, determining the heating scenario corresponding to the steering wheel includes: when the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is less than or equal to a first temperature difference threshold, the heating scenario is determined to be a normal unheated scenario; wherein, the threshold determination algorithm corresponding to the normal unheated scenario is used to determine the preset capacitance threshold corresponding to the normal unheated scenario based on the inherent parasitic capacitance of the heating element and the preset effective grip capacitance of the steering wheel.

[0017] Based on the aforementioned technical methods, for typical unheated scenarios (where the heating element is not working and the external temperature of the steering wheel is basically the same as the ambient temperature), a threshold determination algorithm is adopted, using a base threshold determined by the inherent parasitic capacitance of the heating element and the preset effective grip capacitance of the steering wheel. In this scenario, temperature disturbances are minimal, eliminating the need for additional temperature compensation factors. Stable and accurate judgment criteria can be obtained directly using the intrinsic hardware parameters and typical grip capacitance, reducing computational complexity while ensuring detection efficiency under conditions without thermal interference.

[0018] Furthermore, the heating scenario corresponding to the steering wheel is determined, including: when the heating element is in heating mode and the rate of change of the external temperature of the steering wheel is greater than a first rate of change threshold, the heating scenario is determined to be a heating period scenario; or, when the heating element is in heating mode and the duration for which the rate of change of the external temperature of the steering wheel is less than or equal to a second rate of change threshold reaches a preset stable duration, the heating scenario is determined to be a heating stable scenario; wherein, the threshold determination algorithm corresponding to the heating period scenario or the heating stable scenario is used to determine the preset capacitance threshold corresponding to the heating period scenario or the heating stable scenario based on the product of the basic threshold and the third temperature compensation factor; the third temperature compensation factor is determined based on the external temperature of the steering wheel and the initial internal temperature of the steering wheel when the heating element is turned on, as well as the deviation between the internal temperature of the steering wheel and the corresponding calibrated temperature.

[0019] Based on the aforementioned technical methods, for both heating and stable heating scenarios, a threshold determination algorithm dynamically adjusts the preset capacitance threshold by introducing a third temperature compensation factor (combining the deviation between the external temperature of the steering wheel and the initial internal temperature when heating is turned on, as well as the deviation between the internal temperature and its own calibrated temperature). During heating, the temperature change rate is large, and even after heating stabilizes, the temperature may still be higher than the ambient temperature. In both scenarios, the capacitance sensing is significantly affected by the change in temperature field distribution caused by heating. This solution distinguishes between the transient and steady-state phases during the heating process and employs a unified but dynamic compensation model to ensure that the hand-off detection threshold always matches the real-time thermal state throughout the entire heating cycle, preventing the increase or decrease in capacitance value caused by heating from being misinterpreted as gripping the wheel or releasing the hand.

[0020] Furthermore, determining the heating scenario corresponding to the steering wheel includes: when the working state of the heating element changes from the end of the heating mode and the rate of change of the external temperature of the steering wheel is less than or equal to the first rate of change threshold and continues to reach a preset stable duration, the heating scenario is determined to be a heating off transition scenario; wherein, the threshold determination algorithm corresponding to the heating off transition scenario is used to determine the preset capacitance threshold corresponding to the heating scenario based on the preset capacitance threshold corresponding to the heating scenario at the moment before entering the heating off transition scenario and the preset capacitance threshold under the normal non-heating scenario.

[0021] Based on the aforementioned technical methods, for the transitional scenario of heating off (the steering wheel temperature gradually drops after the heating element stops working), a progressive threshold adjustment strategy is adopted using a threshold determination algorithm based on the previous scenario threshold and the threshold of the normal unheated scenario. Since the temperature does not recover instantly after heating is turned off, there is a hysteresis effect in the capacitive sensing state; immediately switching back to the normal threshold may cause misjudgment. This solution, by smoothly transitioning between the previous scenario threshold (higher or lower) and the normal threshold, and by approximating it cycle by cycle using multiple control cycles, effectively suppresses abrupt changes in capacitive detection caused by temperature hysteresis, achieving a smooth transition and continuous reliability of the hand-off judgment during heating off.

[0022] Furthermore, the process of determining the preset capacitance threshold for the heating transition scenario includes: within multiple consecutive control cycles during the heating transition scenario, each control cycle corresponds to a preset capacitance threshold; the preset capacitance threshold corresponding to the heating scenario just before entering the heating transition scenario is determined as the preset capacitance threshold of the first control cycle; the first control cycle is the first control cycle among multiple consecutive control cycles; the preset capacitance threshold under the normal unheated scenario is determined as the preset capacitance threshold of the second control cycle; the second control cycle is the last control cycle among multiple consecutive control cycles; according to a preset gradation rule, based on the preset capacitance threshold of the first control cycle, the preset capacitance threshold of the second control cycle is approximated cycle by cycle to determine the preset capacitance threshold for the heating transition scenario.

[0023] Based on the aforementioned technical methods, the method for gradually determining the preset capacitance threshold in the transition scenario of turning off heating is further refined: the threshold at the moment before entering the transition scenario is used as the threshold for the first control cycle, and the threshold of the normal unheated scenario is used as the threshold for the last control cycle. In each intermediate control cycle, the threshold is approximated cycle by cycle according to a preset gradual change rule (such as linear or exponential decrease). This gradual adjustment method avoids state jumps caused by abrupt threshold changes, ensuring that the hand-off detection results remain consistent during the slow temperature drop, while allowing the system to continuously output a reliable contact status throughout the transition cycle.

[0024] Furthermore, the method in the first aspect also includes: after determining the contact state as the "touching the disc" state, acquiring the vehicle torque sensing value; when the torque sensing value is greater than or equal to a first torque threshold, correcting the contact state from the "touching the disc" state to the "gripping the disc" state; when the torque sensing value is less than the first torque threshold, and the rate of change of any real-time temperature in the multimodal real-time temperature is greater than the corresponding preset temperature stability threshold, re-determining the contact state after a preset control cycle; the preset control cycle is any one of the multiple continuous control cycles in the current heating scenario; when the rate of change of the multimodal real-time temperature is less than or equal to the corresponding preset temperature stability threshold, directly determining the contact state as the "touching the disc" state.

[0025] Based on the aforementioned technical methods, after determining the contact state as a "touching" state, a secondary confirmation is performed using torque sensor values: if the torque value reaches a high threshold, it is corrected to a "gripping" state to avoid being misjudged as touching the wheel when lightly gripping but intentionally controlling it; if the temperature change rate exceeds a stable threshold, the determination is delayed by one control cycle to avoid prematurely outputting the "touching" state under dynamic temperature fluctuations; if the temperature is stable, the "touching" state is output directly. This multimodal fusion and adaptive delay mechanism introduces steering wheel mechanical information and thermal stability verification into the ambiguous "touching" range, significantly improving the robustness and safety of contact state determination and preventing misjudgments caused by brief thermal disturbances or weak grip force.

[0026] Furthermore, the contact states include the grip state, the touch state, and the hands-free state; the method also includes: when the contact state is determined to be the hands-free state, the current vehicle speed is greater than or equal to a preset speed threshold, and the hands-free duration is less than or equal to a first warning duration, a level one alarm is triggered, which is used to indicate a warning on the instrument panel; when no effective response from the driver is detected after the level one alarm is triggered, and the hands-free duration is less than or equal to a second warning duration, a level two alarm is triggered, which is used to indicate a warning on the instrument panel and an alarm sound; when no effective response from the driver is detected after the level two alarm is triggered, and the hands-free duration reaches a third preset warning duration, a level three warning is triggered, which is used to indicate that the assisted driving function is discontinued and a preset risk response strategy is activated; when the temperature drift of the target capacitor value is detected to exceed a preset drift tolerance threshold, and the abnormal state duration reaches a preset fault confirmation duration, the combined driving assistance function is disabled within a preset penalty duration.

[0027] Based on the aforementioned technical means, a tiered early warning and safety response mechanism has been established for hands-free driving: Level 1 alarms (instrument panel visual), Level 2 alarms (visual + audible), and Level 3 warnings (disengagement of assisted driving and execution of risk strategies) are triggered sequentially according to vehicle speed and duration of hands-free driving. Simultaneously, when capacitor temperature drift exceeds the tolerance threshold and the anomaly persists, the combined driving assistance functions are disabled for the penalty period. This progressive alarm and fault-tolerant design provides the driver with sufficient time to take over and allows for timely downgrading or disengagement when system reliability declines, effectively balancing the safety of assisted driving with user experience and meeting functional safety requirements.

[0028] Furthermore, the method in the first aspect also includes: in the heating scenario, the heating duration, the switching protection duration, and the capacitor detection duration are executed sequentially within each preset control cycle; each preset control cycle is any one of multiple consecutive control cycles in the heating scenario; wherein, the heating duration is the preset control cycle minus the sum of the switching protection duration and the capacitor detection duration; the heating duration is determined based on the difference between the external temperature of the steering wheel and the preset target temperature; the preset target temperature is determined based on the driver's needs.

[0029] Based on the aforementioned technical means, within each preset control cycle, the cycle duration is divided into three time periods: heating duration, switching protection duration, and capacitor detection duration. The heating duration is dynamically adjusted based on the difference between the external temperature of the steering wheel and the target temperature. This time-division multiplexing design allows the heating element to complete its heating task within the same cycle (adjusting the heating time based on demand) while ensuring an independent period for capacitor detection (switching protection is used to isolate heating interference), thus achieving the coexistence of heating and detection functions without mutual interference. Adjusting the heating duration based on the temperature difference also enables closed-loop temperature control, meeting the driver's thermal comfort needs while avoiding crosstalk between heating and capacitor detection.

[0030] Secondly, this application provides an electronic device comprising: a processor and a memory; the memory storing processor-executable instructions. When the processor is configured to execute the instructions, the electronic device implements the method described in the first aspect.

[0031] Thirdly, this application provides a vehicle that includes the electronic equipment described in the third aspect.

[0032] Fourthly, this application provides a computer-readable storage medium that, when the instructions in the computer-readable storage medium are executed by a vehicle's processor, enables the vehicle to perform the methods described in the first aspect and any of their possible implementations.

[0033] Fifthly, this application provides a computer program product including computer instructions that, when executed on a vehicle, cause the vehicle to perform the method described in the first aspect and any possible implementation thereof.

[0034] It should be noted that the technical effects of any of the implementation methods in aspects two through five can be found in the technical effects of the corresponding implementation methods in aspect one, and will not be repeated here.

[0035] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0036] Figure 1 A schematic diagram illustrating the composition of a steering wheel hands-off detection system provided in an embodiment of this application; Figure 2 A schematic diagram illustrating the composition of another steering wheel hands-off detection system provided in an embodiment of this application; Figure 3 A flowchart illustrating a method for detecting when a steering wheel is removed from hands, provided in an embodiment of this application; Figure 4 A flowchart illustrating a method for detecting hand-off detection in a pallet-touching state, provided in an embodiment of this application; Figure 5 A time-sharing timing diagram of a steering wheel hands-off detection method provided in an embodiment of this application; Figure 6 A schematic diagram illustrating the workflow of a steering wheel hands-off detection method provided in this application embodiment; Figure 7 This is a schematic diagram of the composition of an electronic device provided in an embodiment of this application. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] It should be noted that in the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0039] In the embodiments of this application, the terms "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," "fourth," "fifth," and "sixth" may explicitly or implicitly include one or more of that feature.

[0040] In embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. For "A and / or B," this includes three combinations: A only, B only, and a combination of A and B.

[0041] As automotive intelligence gradually advances to L2+ and higher levels, hands-off detection (HOD), as a core module for driver status monitoring, is crucial for ensuring the safety of assisted driving. Current mainstream HOD solutions include indirect torque detection and direct capacitance detection, both of which generally suffer from hardware redundancy, high costs, and poor structural integration. Especially after removing the shielding layer, issues such as full-temperature drift, air conditioning airflow disturbance, and coupling interference between board temperature and ambient temperature become prominent. Traditional single-temperature compensation methods are difficult to adapt to automotive-grade wide-temperature-range operating conditions, easily leading to capacitance signal drift and detection misjudgments. Furthermore, existing technologies have imperfect scenario adaptation logic, limited compensation algorithm dimensions, and torque detection solutions still have blind spots in operating conditions. Related patents have also failed to address core pain points such as heating electrode reuse and multi-factor coupling interference, failing to meet the high-precision, full-scenario, and mass-producible hands-off detection requirements of advanced assisted driving.

[0042] Based on this, this application provides a method for detecting steering wheel hands-off detection. The method first accurately classifies heating scenarios by combining the working state of the heating element and multimodal real-time temperatures (external, internal, and ambient temperatures of the steering wheel). Then, a compensation coefficient is constructed based on the deviation between the multimodal real-time temperatures and the calibrated temperature. This coefficient is used to correct the original capacitance value collected by the heating element through temperature compensation to obtain the target capacitance value. Finally, a preset capacitance threshold corresponding to different heating scenarios is matched to determine the driver's contact state. The preset capacitance thresholds for different heating scenarios are determined based on the corresponding threshold determination algorithm for each heating scenario. By distinguishing differentiated heating scenarios and introducing a multi-dimensional temperature deviation compensation mechanism, and dynamically setting the preset capacitance thresholds based on the threshold determination algorithm corresponding to each heating scenario, the method effectively eliminates the interference of temperature fluctuations such as high and low temperatures and steering wheel heating operation on the accuracy of capacitance detection. This avoids data drift and misjudgment caused by temperature changes, significantly improving the accuracy and stability of steering wheel hands-off detection results and ensuring the reliability of vehicle driving assistance control.

[0043] The embodiments of this application are described below with reference to the accompanying drawings.

[0044] Please see Figure 1 , Figure 1 This is a schematic diagram of the composition of a steering wheel hands-off detection system provided in an embodiment of this application. The steering wheel hands-off detection system includes: a steering wheel, an integrated HOD hands-off detection module, a domain controller, and an intelligent driving controller.

[0045] The sensing layer inside the steering wheel is connected to the capacitive chip in the integrated HOD hands-off detection module via hard wiring. The capacitive chip communicates with the microprocessor chip via the serial peripheral interface (SPI) bus. The microprocessor chip communicates with the domain controller via the local interconnect network (LIN) bus. The domain controller communicates with the intelligent driving controller via the Ethernet (ETH) bus.

[0046] The steering wheel has a three-layer independent structure, consisting of a sensing layer (outermost layer), a shielding layer (middle layer), and a heating layer (innermost layer) from the outside to the inside. The sensing layer is an independently arranged capacitive sensing electrode, the shielding layer is a special electromagnetic shielding material layer, and the heating layer is a heating element (such as a heating wire). The three layers are connected to the rear module through a flexible ribbon cable.

[0047] As one possible implementation, the steering wheel receives heating control commands through the heating layer to realize the steering wheel heating function; the sensing layer collects the capacitance signal corresponding to the driver's grip state and transmits it to the back-end module through hard wiring; the shielding layer does not participate in software interaction and only realizes electromagnetic isolation at the hardware level.

[0048] The integrated HOD (Hands-Off Detection) module mainly consists of a capacitor chip, a microprocessor chip, and a ground terminal (GND). The capacitor chip is connected to the steering wheel sensing layer via a hardwire, and the microprocessor chip communicates with the capacitor chip via the SPI bus and is also connected to the domain controller via the LIN bus.

[0049] In one possible implementation, the capacitor chip is responsible for acquiring the raw capacitance signal of the sensing layer and performing analog-to-digital conversion; the microprocessor chip runs the hands-off detection algorithm, including temperature compensation, threshold comparison, and state determination, and outputs the hands-off detection result via the LIN bus; the heating module drives the heating layer to heat up via hardwire according to the control signal from the microprocessor chip. In another possible implementation, the integrated HOD hands-off detection module is configured to: control the capacitor chip to acquire the raw capacitance data output from the steering wheel sensing layer, perform basic filtering on the data, execute hands-off state determination logic, generate a hands-off state signal, and send the state signal to the domain controller via the LIN bus.

[0050] The domain controller hardware integrates a heating module, a LIN communication interface, an ETH communication interface, and a vehicle battery voltage (VBAT) power supply interface; the heating module is connected to the steering wheel heating layer, the LIN interface is connected to the HOD module, the ETH interface is connected to the intelligent driving controller, and the entire vehicle is powered through VBAT and GND.

[0051] As one possible implementation, the domain controller is configured to: send heating drive commands to the steering wheel heating layer, receive hands-off status signals sent by the integrated HOD hands-off detection module, and forward the status data to the intelligent driving controller via the ETH bus, thereby realizing vehicle-wide interaction between heating control and hands-off status.

[0052] The intelligent driving controller is the core control unit of the vehicle's advanced driver assistance system. It has an ETH communication interface, which can receive various status signals forwarded by the domain controller and output driver assistance control commands.

[0053] As one possible implementation, the intelligent driving controller receives the steering wheel off-hand status signal forwarded by the domain controller, combines it with information such as vehicle speed and road conditions to determine the driver takeover status, and then controls the start / stop, alarm and exit strategies of the assisted driving functions.

[0054] but, Figure 1 The system shown has the following drawbacks: the steering wheel adopts a three-layer separate structure of heating layer, shielding layer and sensing layer, which has high hardware redundancy and complex wiring, thus increasing material and assembly costs; the independently set shielding layer and sensing layer increase the thickness of the steering wheel, which is not conducive to the lightweighting and platform design of the whole vehicle; at the same time, the heating function and the hands-off detection function are independent of each other, and the hardware is not deeply reused, resulting in low system integration. Moreover, after removing the shielding layer, it is susceptible to temperature drift and electromagnetic interference, which leads to a decrease in detection accuracy and cannot meet the requirement of simultaneous operation of heating and hands-off detection functions.

[0055] Based on this, this application provides a schematic diagram of another steering wheel hands-off detection system, such as... Figure 2 As shown. The steering wheel hands-off detection system includes: a steering wheel, an integrated HOD hands-off detection module, a domain controller, and an intelligent driving controller.

[0056] The sensing and heating layers (i.e., the multiplexed layers) inside the steering wheel are connected to the capacitance detection unit in the integrated HOD hands-off detection module via hard wiring; the heating module in the integrated HOD hands-off detection module communicates with the microprocessor chip, and the capacitance detection unit is connected to the microprocessor chip via the SPI bus; the microprocessor chip communicates with the domain controller via the LIN bus, and the domain controller communicates with the intelligent driving controller via the ETH bus; the integrated HOD hands-off detection module also obtains power through VBAT and is grounded through GND.

[0057] The steering wheel adopts a single-layer reusable structure, with only a combined sensing and heating layer, eliminating the independent shielding layer. The reusable layer is composed of steering wheel heating elements (such as heating wires), which have both heating and capacitive sensing functions, and is connected to the integrated HOD hands-off detection module via hard wiring.

[0058] As one possible implementation, the steering wheel is configured to: execute heating commands and acquire capacitance signals in a time-division multiplexing manner; in heating mode, receive heating drive commands to achieve steering wheel heating; in detection mode, acquire capacitance signals corresponding to the driver's grip state and transmit them to the back-end module via hardwire, thereby realizing hardware multiplexing of heating and hands-off detection functions.

[0059] The integrated HOD hands-off detection module mainly includes a capacitance detection unit, a microprocessor chip, a heating module, a VBAT power supply interface, and a GND ground terminal. The capacitance detection unit is connected to the steering wheel multiplexing layer via a hardwired connection, the heating module is connected to the multiplexing layer, the microprocessor chip communicates with the capacitance detection unit via the SPI bus, and is also connected to the domain controller via the LIN bus.

[0060] As one possible implementation, the integrated HOD hands-off detection module is configured to: control the heating module to output heating drive signals to the steering wheel reuse layer in a time-sharing manner; control the capacitance detection unit to collect the raw capacitance data output by the reuse layer; perform multi-dimensional temperature compensation, scenario-based dynamic threshold determination and hands-off status adjudication on the collected capacitance data; generate a standardized hands-off status signal; and send the status signal to the domain controller via the LIN bus.

[0061] The domain controller includes a LIN transceiver, an ETH transceiver, and a main control chip. As one possible implementation, the domain controller receives hands-free detection results, combines them with signals such as vehicle speed and EPS torque to make decisions, and generates tiered prompts (optical, acoustic) or driver assistance exit commands.

[0062] The intelligent driving controller is the core control unit of the vehicle's advanced driver assistance system (ADAS) in terms of hardware. It has an ETH communication interface, which can receive various status signals forwarded by the domain controller and output assisted driving control commands. As one possible implementation, the intelligent driving controller is used to receive the steering wheel off-hand status signal forwarded by the domain controller, and combine it with information such as vehicle speed and road conditions to determine the driver take-over status, and then control the start, stop, alarm, and exit strategies of the assisted driving functions.

[0063] As one possible implementation, the steering wheel off-hand detection method provided in this application embodiment can be applied to an integrated HOD (Hands-Off Detection) module.

[0064] It should be noted that, in the embodiments of this application, Figure 1 or Figure 2 The illustrated structure does not constitute a limitation on the hands-off detection system for the steering wheel of this application. The system may include more or fewer components than shown in the figures, or combine or separate certain components, or employ different component arrangements. The components shown in the figures can be implemented in hardware, software, or a combination of both.

[0065] For ease of understanding, the steering wheel hands-off detection method provided in this application will be described in detail below with reference to the accompanying drawings.

[0066] Figure 3 This is a flowchart illustrating a method for detecting when a steering wheel is removed from hands, provided in an embodiment of this application. (Refer to...) Figure 3 The method for detecting when the steering wheel is off-hand includes: S301. Based on the working status of the steering wheel's heating element and / or the multimodal real-time temperature, determine the heating scenario corresponding to the steering wheel.

[0067] The multimodal real-time temperature includes the external temperature of the steering wheel, the internal temperature of the steering wheel, and the ambient temperature; the heating element is configured to generate heat when energized in heating mode and to function as a capacitive sensing electrode in detection mode.

[0068] As one possible implementation, the heating element can be a heating wire, whose operating states include: an active state (i.e., in heating mode, energized and generating heat) and an inactive state (i.e., in detection mode, not energized and generating heat, only acting as a capacitive sensing electrode). During certain transition phases, the system can also identify a special state "within a short period after switching from active to inactive" to facilitate a smooth transition.

[0069] As one possible implementation, the external temperature of the steering wheel can be obtained by one or more NTC thermistor sensors located beneath the foam layer on the steering wheel surface or in the grip area. This external temperature reflects the actual temperature of the area in contact with the driver's hands, directly affecting the dielectric constant of the dielectric material surrounding the heating wire (as a capacitance sensing electrode), thus causing a drift in the original capacitance value.

[0070] Understandably, the subsequent multimodal real-time temperature can be used to construct the first deviation term in the compensation coefficient to offset the dielectric temperature drift of the steering wheel surface; it can also be used for heating scene recognition (e.g., in the case of direct air conditioning blowing, the temperature difference between the outside of the steering wheel and the ambient temperature is large); and it can also be used to calculate the PID heating duration in the heating scene as a real-time feedback value.

[0071] As one possible implementation, the internal temperature of the steering wheel can be obtained using an NTC thermistor sensor mounted on the printed circuit board (PCB) inside the steering wheel. The internal temperature of the steering wheel reflects the operating environment temperature of the circuit board and the capacitive sensing chip; temperature changes on the PCB board can cause zero-point drift of the capacitive sensing chip and fluctuations in the reference signal.

[0072] Understandably, the internal temperature of the steering wheel can be used to construct the second deviation term in the compensation coefficient to offset the temperature drift of the circuit board itself; it can also be used to identify cold-start power-on scenarios (the PCB board temperature rises rapidly); and it can also be used to determine heating stability scenarios (the internal temperature tends to stabilize).

[0073] As one possible implementation, ambient temperature is obtained through a temperature sensor installed inside the vehicle (e.g., on the dashboard, near the air conditioning ducts, or in the rearview mirror housing). Ambient temperature provides an environmental reference benchmark inside the vehicle, helping to distinguish between different thermal conditions such as direct air conditioning or starting the engine when it is cold.

[0074] Understandably, the ambient temperature can be used to construct the third deviation term in the compensation coefficient to compensate for the impact of ambient temperature on the overall measurement chain; it can also be used to identify direct air conditioning blowing scenarios (comparing the temperature difference with the outside temperature of the steering wheel); and it can also serve as a reference for judging the "cold car" state in the cold car power-on scenario.

[0075] As another possible implementation, the heating scenario corresponding to the steering wheel is determined based on the operating status and / or multimodal real-time temperature of the steering wheel's heating element, as well as the ambient airflow speed.

[0076] The operating status of the heating element, the method of obtaining multimodal real-time temperature, and the installation location can be found in the above description, and will not be repeated here.

[0077] One implementation method involves acquiring the ambient airflow velocity via an airflow sensor, or indirectly determining the airflow intensity and direct airflow status using a soft recognition method. For example, in the "no wind" level—where the absolute value of the temperature difference between the steering wheel exterior and the ambient temperature is ≤5℃ and the rate of change of the steering wheel exterior temperature is ≤0.2℃ / 100ms—the airflow quantization value W=0; in the "light wind" level—where 5℃ < absolute temperature difference ≤8℃ or 0.2℃ / 100ms < rate of change of temperature ≤0.3℃ / 100ms—the airflow quantization value W=1; and in the "strong direct airflow" level—where the absolute temperature difference >8℃ or the rate of change of temperature >0.3℃ / 100ms—the airflow quantization value W=2. By introducing soft-recognition airflow quantization values, airflow interference conditions such as direct airflow from the air conditioner can be effectively determined without the need for additional airflow sensors, further reducing system hardware costs. For example, in cold-start scenarios or direct airflow scenarios, the NTC sensor group and the ambient temperature sensor are upgraded to a 50Hz high-frequency acquisition, and the airflow sensor acquires data at 50Hz.

[0078] As one possible implementation, the working scenarios related to steering wheel heating are divided into the following types, and different preset capacitor thresholds and scheduling strategies will be adopted for different scenarios in subsequent steps. The working scenarios related to steering wheel heating include: (1) When the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is greater than the first temperature difference threshold, the heating scenario is determined to be the direct air conditioning scenario.

[0079] In one implementation, the operating state of the heating element not being in heating mode can be determined by a heating enable signal.

[0080] The heating enable signal is generated by the steering wheel heating control switch or the vehicle thermal management controller, and can be sent to the microprocessor chip of the integrated HOD hands-off detection module in the form of high / low level or CAN / LIN message.

[0081] For example, when the driver presses the heating button on the steering wheel, the hardwire level changes from low to high, or the domain controller sends a "heating on" command via the LIN bus. Upon receiving this command, the microprocessor chip determines that the heating enable signal is active. In this scenario, the heating enable signal is inactive (e.g., the level is 0 or no heating command has been received). Simultaneously, assuming the first temperature difference threshold is 5°C, if the external temperature of the steering wheel is 18°C ​​and the ambient temperature is 28°C, the absolute temperature difference is 10°C > 5°C, then the system determines that the current scenario is a direct air conditioning blast scenario.

[0082] (1) Another implementation method is to determine the heating scenario as the direct air conditioning blowing scenario when the heating element is not in the heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is greater than the first temperature difference threshold, or the ambient airflow speed is greater than the first airflow threshold.

[0083] For example, if the external temperature of the steering wheel is 18°C ​​and the ambient temperature is 28°C, the absolute temperature difference is 10°C, which is greater than the first temperature difference threshold of 5°C, or the airflow velocity measured by the airflow sensor is 4 m / s, which is greater than the first airflow threshold of 2 m / s, then the system determines that the current scenario is a direct airflow scenario. It should be understood that in a direct airflow scenario, because the cold air blows directly onto the surface of the steering wheel, the capacitance signal will drift due to the low temperature. Therefore, it is necessary to use a temperature compensation factor based on the external temperature of the steering wheel and the ambient temperature, or the ambient airflow velocity, to adjust the preset capacitance threshold.

[0084] (2) When the heating element is not in heating mode, and the vehicle power-on time is less than or equal to the preset power-on time threshold, and the rate of change of the steering wheel internal temperature is greater than the second rate of change threshold, the heating scenario is determined to be the cold vehicle power-on scenario.

[0085] One implementation method is to accumulate the vehicle's power-on time from the moment the vehicle power supply (such as KL15) is powered on using a timer inside the microprocessor chip.

[0086] For example, the preset power-on duration threshold is set to 3 minutes (180 seconds), and the second rate of change threshold is set to 0.5℃ / 100ms. Assuming the vehicle has just been powered on for 30 seconds, the initial temperature of the steering wheel internal temperature sensor (mounted on the PCB board) is -15℃, and then rises to -14.4℃ within 100ms, with a rate of change of 0.6℃ / 100ms, which is greater than 0.5℃ / 100ms. Therefore, the system determines that the current situation is a cold start scenario.

[0087] It should be understood that in the scenario of cold vehicle power-on, the PCB board heats up rapidly due to self-heating when powered on, causing additional drift in the capacitor sensing circuit. Therefore, a second temperature compensation factor based on the deviation between the internal temperature of the steering wheel and the initial internal temperature of the steering wheel when the vehicle is powered on is required to adjust the preset capacitor threshold.

[0088] (3) When the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is less than or equal to the first temperature difference threshold, the heating scenario is determined to be the normal unheated scenario.

[0089] For example, the first temperature difference threshold of 5°C is used again. If the external temperature of the steering wheel is 22°C, the ambient temperature is 24°C, the absolute temperature difference is 2°C ≤ 5°C, and the heating enable signal is inactive, the system determines it to be a normal unheated scenario.

[0090] (3) Another implementation method is to determine the heating scenario as a normal unheated scenario when the heating element is not in heating mode, the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is less than or equal to the first temperature difference threshold, and the ambient airflow speed is greater than the first airflow threshold.

[0091] For example, let the first temperature difference threshold be 5℃ and the first airflow threshold be 2m / s. If the external temperature of the steering wheel is 22℃, the ambient temperature is 24℃, the absolute temperature difference is 2℃≤5℃, and the ambient airflow velocity measured by the airflow sensor is 2.3m / s, which is greater than 2m / s, then the system determines it to be a normal unheated scenario.

[0092] It should be understood that although there is airflow disturbance, the actual direct airflow effect of the air conditioner is not obvious because the external temperature of the steering wheel is close to the ambient temperature. Therefore, it is still classified as a normal unheated scenario. At this time, the capacitance signal is mainly affected by the stable temperature. A fixed preset capacitance threshold (e.g., the first capacitance threshold is 2.3pF, and the second capacitance threshold is 1.84pF) can be used without additional temperature compensation. The common feature of the above scenarios (1)-(3) is that when the heating element is inactive (i.e., there is no heating interference), there is no need for time-sharing scheduling, and the heating wire can be used as the capacitance sensing electrode throughout the process. The original capacitance signal is mainly affected by the temperature difference between the external temperature of the steering wheel and the ambient temperature, the rise of the internal temperature of the steering wheel (PCB board temperature), and the interference of airflow disturbance. It needs to be supplemented and calibrated by the NTC temperature sensor group (including the external temperature sensor of the steering wheel, the internal temperature sensor of the steering wheel, the ambient temperature sensor, or the airflow sensor) to offset the drift.

[0093] For example, the above (1)-(3) scenarios correspond to the following vehicle use scenarios: regular unheated scenario (e.g., normal temperature vehicle use in spring and autumn, steering wheel heating not turned on in winter), cold start scenario (i.e., the initial stage of cold start), and air conditioning direct blowing scenario (determined by the ambient airflow speed when there is an airflow sensor, and determined by the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature when there is no airflow sensor), and also includes the vehicle ventilation direct blowing steering wheel scenario.

[0094] (4) When the heating element is in heating mode and the rate of change of the external temperature of the steering wheel is greater than the first rate of change threshold, the heating scenario is determined to be the heating period scenario.

[0095] In one implementation, when the heating element is in heating mode, the heating enable signal is activated (e.g., a hard-line high level or a heating command received).

[0096] For example, the first rate of change threshold is set to 0.3℃ / 100ms. Assuming the initial external temperature of the steering wheel is -10℃, after the driver turns on the heater, the temperature rises to -9.5℃ within 100ms, and the rate of change is 0.5℃ / 100ms > 0.3℃ / 100ms, then it is determined to be a scenario during heating.

[0097] (4) Another implementation method is to determine the heating scenario as the heating period scenario when the heating element is in the heating mode, the change rate of the external temperature of the steering wheel is greater than the first change rate threshold, and the ambient airflow speed is greater than the second airflow threshold.

[0098] For example, let the first rate of change threshold be 0.3℃ / 100ms and the second airflow threshold be 3m / s. If the external temperature change rate of the steering wheel is 0.5℃ / 100ms (greater than 0.3℃ / 100ms), and the ambient airflow velocity measured by the airflow sensor is 4m / s (greater than 3m / s), then the current scenario is determined to be during heating. When the ambient airflow velocity exceeds the second airflow threshold, the second airflow threshold can be appropriately adjusted to improve the sensitivity of identifying airflow disturbance conditions.

[0099] It should be understood that during the heating process, the temperature rises rapidly, and the superposition of heating interference, temperature change interference, and airflow disturbance causes severe drift in the capacitor signal. Therefore, a third temperature compensation factor based on the external temperature of the steering wheel, the initial internal temperature of the steering wheel when heating is turned on, and the deviation between the internal temperature of the steering wheel and the calibrated temperature is required to adjust the preset capacitor threshold. At the same time, airflow sensor data is used for auxiliary compensation, and time-sharing scheduling is performed (working in the sequence of "heating time + protection time + detection time" in each control cycle).

[0100] The heating period corresponds to the following vehicle usage scenarios: the initial stage of steering wheel heating, such as when heating a cold car in winter or heating as needed in spring and autumn, accompanied by air conditioning or ventilation blowing directly on the steering wheel (ambient airflow speed ≥2m / s).

[0101] (5) When the heating element is in heating mode and the duration of the change rate of the external temperature of the steering wheel being less than or equal to the second change rate threshold reaches the preset stable duration, the heating scenario is determined to be a heating stable scenario.

[0102] For example, the preset stabilization time is 500ms. Assuming the external temperature of the steering wheel has risen to 37.5℃, and within five consecutive control cycles (each cycle 100ms), the temperature change rate of each cycle is 0.2℃ / 100ms, 0.15℃ / 100ms, 0.1℃ / 100ms, 0.1℃ / 100ms, and 0.1℃ / 100ms respectively, all less than or equal to 0.3℃ / 100ms, and the duration reaches 500ms, then the system determines it to be a heating stabilization scenario.

[0103] (5) In another implementation, when the heating element is in heating mode, and the duration for which the rate of change of the external temperature of the steering wheel is less than or equal to the second rate of change threshold reaches a preset stabilization time, and the ambient airflow speed is greater than the second airflow threshold, the heating scenario is determined to be a stable heating scenario. Wherein, when the ambient airflow speed is greater than the second airflow threshold, the preset stabilization time can be appropriately shortened (for example, adjusted from 500 milliseconds to 400 milliseconds) to respond more quickly to the determination of the stable state under airflow disturbance.

[0104] For example, let the first rate of change threshold be 0.3℃ / 100ms, the preset stabilization time be 500ms, the second airflow threshold be 3m / s, and the preset airflow stabilization time be 300ms. If the rate of change of the external temperature of the steering wheel for five consecutive control cycles (each cycle being 100ms) is 0.2℃ / 100ms, 0.15℃ / 100ms, 0.1℃ / 100ms, 0.1℃ / 100ms, and 0.1℃ / 100ms respectively, all of which are less than or equal to 0.3℃ / 100ms, and the duration of the ambient airflow speed being greater than 3m / s for 300ms within the aforementioned consecutive 500ms reaches 300ms, then the system determines it to be a heating stabilization scenario and dynamically adjusts the preset stabilization time to 400ms.

[0105] It should be understood that in a stable heating scenario, temperature fluctuations are gradual and heating interference is constant. However, airflow disturbances may cause slight jitter in the capacitor signal. Fine-tuning and supplementary calibration using the NTC temperature sensor group, ambient temperature sensor, and airflow sensor are necessary to suppress the impact of airflow jitter. This stable heating scenario corresponds to the following vehicle usage scenarios: the steering wheel heating and heat preservation stage (such as prolonged heating in winter, with air conditioning blowing directly on the steering wheel), where the external temperature of the steering wheel remains constant, accompanied by direct air conditioning or ventilation (ambient airflow speed ≥2m / s).

[0106] (6) When the working state of the heating element changes from the end of the heating mode and the rate of change of the external temperature of the steering wheel is less than or equal to the first rate of change threshold and continues to reach the preset stable duration, the heating scenario is determined to be the heating off transition scenario.

[0107] In one implementation, when the heating element's working state ends after the heating mode is completed, i.e., after the driver turns off the heating function after the steering wheel heating has stabilized, the heating enable signal changes from active to inactive, and the microprocessor chip records the switching time.

[0108] For example, within the subsequent 500ms (i.e., 5 control cycles, each 100ms), it is determined to be a transitional scenario where the heating is turned off. For instance, when the heating is turned off, the external temperature of the steering wheel is 38°C, and the temperature decreases by 0.3°C in the first 100ms after turning off, and by 0.2°C in the second 100ms, and so on, continuously decreasing.

[0109] (6) Another implementation method is to determine the heating scenario as the heating-off transition scenario when the working state of the heating element changes from the end of the heating mode, and the change rate of the external temperature of the steering wheel is less than or equal to the first change rate threshold and continues to reach the preset stable time, and the ambient airflow speed is greater than the second airflow threshold.

[0110] When the ambient airflow velocity is greater than the second airflow threshold (e.g., 3 m / s), the preset compensation time can be appropriately extended (e.g., from 500 milliseconds to 800 milliseconds) to offset the additional impact of airflow disturbance on the stability of the capacitor signal during the residual temperature change of the disk.

[0111] For example, suppose the preset compensation duration is 500ms, the second airflow threshold is 3m / s, and the extended preset compensation duration is 800ms. If the heating enable signal changes from active to inactive, and the ambient airflow speed is measured to be 4m / s (greater than 3m / s) after 300ms of switching, the system will dynamically adjust the preset compensation duration to 800ms, determine that the current scenario is a heating-off transition, and continuously perform threshold gradation and signal smooth transition within 800ms. It should be understood that although heating has stopped in this heating-off transition scenario, the steering wheel still retains residual heat, and airflow disturbance will exacerbate the drift of the capacitor signal. Therefore, it cannot immediately switch back to the normal non-heating threshold, but needs to use a gradual threshold (gradually transitioning from the threshold at the end of the heating scenario to the normal non-heating threshold). The gradation rule can be exponential or linear, that is, it needs to be continuously supplemented and calibrated through the NTC temperature sensor group, ambient temperature sensor, and airflow sensor to achieve a smooth signal transition and offset the residual changes in steering wheel temperature and residual airflow interference. The transitional scenario for turning off the heating corresponds to the following driving scenarios: shortly after the steering wheel heating is turned off (e.g., after heating to a suitable temperature and then turning it off), the external temperature of the steering wheel slowly drops, accompanied by the air conditioning or ventilation blowing directly on the steering wheel (ambient airflow speed ≥2m / s).

[0112] S302. Determine the preset capacitance threshold corresponding to the heating scenario based on the threshold determination algorithm corresponding to the heating scenario.

[0113] It should be understood that different threshold determination algorithms are used to determine the preset capacitance threshold for different heating scenarios. This dynamically adapts to interference factors such as temperature changes, airflow disturbances, and the working status of heating elements in each scenario, so that the preset capacitance threshold can match the current environment and heating conditions in real time. This effectively suppresses capacitance signal drift and ensures the accuracy and stability of the off-hand detection results.

[0114] The heating scenarios include the following: direct air conditioning blowing scenario, cold engine power-on scenario, normal non-heating scenario, heating during scenario, stable heating scenario, and heating off transition scenario.

[0115] As one possible implementation, the threshold determination algorithm for the direct airflow scenario is used to determine the preset capacitance threshold for the direct airflow scenario based on the product of the basic threshold and the first temperature compensation factor. The first temperature compensation factor is determined based on the deviation between the external temperature of the steering wheel, the ambient temperature and their respective calibration temperatures.

[0116] One implementation method involves determining the base threshold based on the inherent parasitic capacitance of the heating element, the preset effective grip capacitance of the steering wheel, and the preset heating interference compensation capacitance. The inherent parasitic capacitance can range from 1.5pF to 2.0pF, with 1.8pF being an option. The preset effective grip capacitance can be 0.5pF, used to accommodate various gripping methods such as pinching and wearing thin gloves. The preset heating interference compensation capacitance can be 0.2pF, used to compensate for thermal noise and current interference during the heating process.

[0117] For example, the base threshold is the sum of the inherent parasitic capacitance of the heating element, the preset effective grip capacitance of the steering wheel, and the preset heating interference compensation capacitance. For instance, if the inherent parasitic capacitance is 1.8 pF, the preset effective grip capacitance is 0.5 pF, and the preset heating interference compensation capacitance is 0.2 pF, then the base threshold is 2.5 pF. During factory calibration, initial calibration is performed in conjunction with the ambient temperature at a standard temperature of 25°C to ensure the accuracy of the reference threshold, laying the foundation for dynamic threshold adjustment in various scenarios and the determination of the driver's and steering wheel's state.

[0118] Another implementation method is to base the threshold based on the inherent parasitic capacitance value of the heating element, the preset effective grip capacitance value of the steering wheel, the preset heating interference compensation capacitance value, and the preset airflow basic interference correction amount.

[0119] For example, the base threshold is the sum of the inherent parasitic capacitance of the heating element, the preset effective grip capacitance of the steering wheel, the preset heating interference compensation capacitance, and the preset airflow basic interference correction. For instance, if the inherent parasitic capacitance is 1.8 pF, the preset effective grip capacitance is 0.5 pF, the preset heating interference compensation capacitance is 0.2 pF, and the preset airflow basic interference correction is 0.1 pF, then the base threshold is 2.6 pF. During factory calibration, initial calibration is performed using ambient temperature data at a standard temperature of 25°C and ambient data under a standard airflow of 1 m / s to ensure that the benchmark threshold can cover the influence of basic airflow disturbances, providing a more comprehensive benchmark for dynamic threshold adjustment and ternary state determination in various scenarios.

[0120] As one possible implementation method, the calibration environment is prepared as follows: The integrated HOD hands-free detection module is placed in an automotive-grade environmental test chamber with a temperature range of -40℃ to 125℃ and a humidity control range of 20% to 80% relative humidity to simulate extreme temperature changes, multiple temperature combinations, and direct air conditioning blowing scenarios in the vehicle (airflow interference is simulated by adjusting the temperature difference in the test chamber, without the need for additional airflow simulation); at the same time, a cold-engine power-on simulation platform is built to realize the dynamic process of the PCB board temperature rapidly rising from -40℃ to 25℃, thus reproducing the environment in which the capacitor sensing electrodes are exposed to real temperature change interference after the shielding layer is removed.

[0121] Another approach involves preparing the calibration environment, which includes simulating airflow velocities ranging from 0 to 5 m / s, divided into four levels: 0 m / s, 2 m / s, 3 m / s, and 5 m / s. Specifically, the integrated HOD (Hands-Off Detection) module is placed in an automotive-grade environmental test chamber. The chamber's temperature range covers -40°C to 125°C, and the humidity is controlled between 20% and 80% relative humidity. An adjustable fan speed generator is installed within the chamber to simulate airflow velocities of 0 m / s, 2 m / s, 3 m / s, and 5 m / s, comprehensively covering air conditioning / ventilation scenarios from no wind to strong direct airflow. Simultaneously, a cold-engine power-on simulation platform is built to simulate the dynamic process of the PCB board temperature rapidly rising from -40°C to 25°C, replicating the environment where the capacitive sensing electrodes are exposed to real temperature changes and airflow coupling interference after the shielding layer is removed. This calibration environment provides more complete data support for the subsequent fitting of compensation coefficients and filtering parameters, ensuring the accuracy and robustness of the hand-off detection under all operating conditions.

[0122] One implementation method involves determining the basic threshold through the following calibration process: Under a stable state of 25°C, without heating, gripping, or airflow, the signal output from the capacitive sensing chip is continuously collected 100 times and the average value is taken to obtain the inherent parasitic capacitance of the heating element as 1.8pF. Subsequently, 20 test subjects with different hand shapes are sampled under two scenarios: bare hands and wearing thin gloves. Interference conditions such as direct airflow from an air conditioner (3m / s airflow) and powering on a cold vehicle (PCB board temperature rise) are superimposed. The capacitance change under the minimum effective gripping state is measured, and the minimum value is taken to obtain the preset effective gripping capacitance as 0.5pF. Then, the heating function is turned on (target temperature 38°C), and a 3m / s airflow disturbance is superimposed. The maximum fluctuation value of the capacitance signal during heating is collected under the state of no gripping to obtain the preset heating interference compensation capacitance as 0.2pF. The above three items are added together, i.e., 1.8pF + 0.5pF + 0.2pF, to obtain the basic threshold of 2.5pF. Initial calibration is completed at a standard temperature of 25°C in conjunction with temperature sensor data.

[0123] One implementation method is that the preset capacitance threshold corresponding to the direct airflow scenario of the air conditioner satisfies the following threshold determination algorithm, the specific relationship is as follows:

[0124] in, This indicates the preset capacitance threshold under direct airflow from an air conditioner. The base threshold is set at 2.5 pF. The first compensator coefficient has a value of 0.0012 per degree Celsius. This is the third compensator coefficient, with a value of 0.0003 per degree Celsius; The steering wheel external temperature is collected in real time; The ambient temperature is collected in real time; The temperature is set to 25 degrees Celsius for calibration.

[0125] For example, let the external temperature of the steering wheel be... Ambient temperature If the calibration temperature is 25℃, then the calculation is as follows: .

[0126] By using the temperature difference data between the steering wheel exterior temperature and the ambient temperature, the threshold can be supplemented and calibrated, effectively offsetting the capacitance drift caused by the temperature difference when the air conditioner blows directly. This allows for accurate adaptation to the scenario without the need for an airflow sensor, avoiding misjudgment.

[0127] Another implementation method, after incorporating ambient airflow speed correction, ensures that the preset capacitance threshold for the direct airflow scenario satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0128] in, This indicates the preset capacitance threshold under direct airflow from an air conditioner. The base threshold is set at 2.6 picofarads. The first compensator coefficient has a value of 0.0012 per degree Celsius. This is the third compensator coefficient, with a value of 0.0003 per degree Celsius; This is the fourth compensator coefficient, with a value of 0.0002 per meter per second; The steering wheel external temperature is collected in real time; The ambient temperature is collected in real time; The calibration temperature is set to 25 degrees Celsius. This represents the real-time ambient airflow velocity (range: 0-5 meters per second).

[0129] For example, let the external temperature of the steering wheel be... Ambient temperature airflow speed If the calibration temperature is 25℃, then the calculation is as follows: One implementation method involves calibrating thresholds based on disk temperature, ambient temperature, and airflow velocity data, with an additional 1.2 times airflow compensation weight added for high airflow scenarios (V_air ≥ 3m / s).

[0130] By utilizing the temperature difference data between the steering wheel's external temperature and the ambient temperature, along with the ambient airflow velocity data collected by the airflow sensor, the threshold is supplemented and calibrated. This effectively counteracts the capacitance drift caused by both temperature difference and airflow disturbance when the air conditioner is blowing directly on the vehicle, thus avoiding misjudgments. This method is suitable for scenarios where only temperature difference is used for judgment when there is no airflow sensor, and it can also optimize the judgment accuracy by combining airflow data when an airflow sensor is present, thereby improving the robustness of hands-off detection in scenarios where the air conditioner is blowing directly on the vehicle.

[0131] As one possible implementation, the threshold determination algorithm for the cold start power-on scenario is used to determine the preset capacitor threshold for the cold start power-on scenario based on the product of the basic threshold and the second temperature compensation factor. The second temperature compensation factor is determined based on the deviation between the steering wheel internal temperature and the initial steering wheel internal temperature when the vehicle is powered on.

[0132] One implementation method is that the preset capacitor threshold corresponding to the cold start power-on scenario satisfies the following threshold determination algorithm, the specific relationship being:

[0133] in, This indicates the preset capacitor threshold for a cold start power-on scenario; The base threshold is set at 2.5 picofarads. This is the second compensator coefficient, with a value of 0.0005 per degree Celsius; The steering wheel internal temperature is collected in real time; The initial internal temperature of the steering wheel was collected when the vehicle was powered on.

[0134] For example, suppose the initial internal temperature of the steering wheel when the vehicle is powered on is... Current steering wheel internal temperature Then the calculation yields: .

[0135] Based on the above relationship, the preset capacitance threshold in the cold start power-on scenario can compensate for the capacitance signal drift caused by the rapid rise in PCB board temperature during the cold start power-on phase, ensuring detection accuracy.

[0136] Another implementation method, after incorporating ambient airflow speed correction, ensures that the preset capacitor threshold for the cold start power-on scenario satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0137] in, This indicates the preset capacitor threshold for a cold start power-on scenario; The base threshold is set at 2.6 picofarads. This is the second compensator coefficient, with a value of 0.0005 per degree Celsius; This is the fourth compensator coefficient, with a value of 0.0002 per meter per second; The steering wheel internal temperature is collected in real time; The initial internal temperature of the steering wheel was collected when the vehicle was powered on; This represents the real-time ambient airflow velocity.

[0138] For example, suppose the initial internal temperature of the steering wheel when the vehicle is powered on is... Current steering wheel internal temperature airflow speed Then the calculation yields: .

[0139] By utilizing the aforementioned relationship and the deviation between the steering wheel's internal temperature and its initial temperature, along with airflow velocity data, the threshold is supplemented and calibrated. This effectively compensates for the capacitance signal drift caused by the rapid temperature rise of the PCB board and airflow disturbances during the cold start-up phase, ensuring detection accuracy. This method is suitable for scenarios where only the board temperature difference is used for judgment when there is no airflow sensor, and it can also be used to optimize the judgment by combining airflow data when an airflow sensor is available.

[0140] As one possible implementation, the threshold determination algorithm for the conventional unheated scenario is used to determine the preset capacitance threshold for the conventional unheated scenario based on the inherent parasitic capacitance of the heating element and the preset effective grip capacitance of the steering wheel.

[0141] For example, if the inherent parasitic capacitance of the heating element is 1.8pF and the preset effective holding capacitance is 0.5pF, then the first capacitance threshold in a normal unheated scenario is the sum of the two, 2.3pF, and the second capacitance threshold is 0.8 times that, i.e., 1.84pF. In this scenario, the temperature is stable and no dynamic compensation is required.

[0142] One implementation method involves a preset capacitance threshold corresponding to a typical unheated scenario that satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0143] in, This indicates the preset capacitance threshold under normal, unheated conditions. The inherent parasitic capacitance of the heating element is taken as 1.8pF; The preset effective holding capacitance is set to 0.5pF. The sum of the two is 2.3pF. One implementation method determines the base threshold in the same way as in the air conditioner direct-blowing scenario described above, and will not be repeated here. In this scenario, the temperature is stable, eliminating the need for frequent temperature compensation. However, the system still combines multimodal real-time temperature to determine the temperature stability state, and performs slight supplementary calibration of the base threshold when necessary to offset environmental temperature drift interference and ensure detection accuracy in normal scenarios.

[0144] For example, a base threshold is set. Second compensator coefficient The initial internal temperature of the steering wheel when the vehicle is powered on. Current steering wheel internal temperature The temperature deviation is The preset capacitor threshold for a cold start power-on scenario is: .

[0145] One implementation involves incorporating ambient airflow velocity correction. The preset capacitance threshold for a typical unheated scenario satisfies the following threshold determination algorithm, with the specific formula as follows: When the ambient airflow speed hour: .

[0146] When the ambient airflow speed hour: .

[0147] in, This refers to the inherent parasitic capacitance of the heating element; Preset effective holding capacitance; This is the correction amount for the basic airflow disturbance. This is the fourth compensator coefficient (airflow compensation coefficient). This represents the real-time ambient airflow velocity.

[0148] For example, when hour, ;when First, calculate the base value. Then multiply by the airflow compensation factor: Since the compensation amount is extremely small, it can be approximated in practice. It can also retain fine-tuning to precisely suppress airflow disturbances.

[0149] Based on the above relationships, the temperature stability is determined by combining data from the NTC sensor array and the ambient temperature sensor, and the airflow intensity is determined by combining data from the airflow sensor. This allows for supplementary calibration of the basic threshold, effectively offsetting slight ambient temperature drift and low airflow disturbance interference, ensuring detection accuracy in typical unheated scenarios. For vehicles without airflow sensors, the airflow term can be ignored, and a fixed threshold can be directly applied. This application can function normally without the mandatory installation of an airflow sensor.

[0150] As one possible implementation, the threshold determination algorithm corresponding to the heating period scenario or the heating stable scenario is used to determine the preset capacitance threshold corresponding to the heating period scenario or the heating stable scenario based on the product of the basic threshold and the third temperature compensation factor; the third temperature compensation factor is determined based on the external temperature of the steering wheel and the initial internal temperature of the steering wheel when the heating element is turned on, as well as the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature.

[0151] One implementation method involves a preset capacitance threshold corresponding to the scene during heating, which satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0152] in, This indicates the preset capacitance threshold during the heating process. The threshold is constrained to a range of 2.0pF to 2.8pF (factory calibration constraint to avoid misjudgment due to abnormal threshold). The base threshold is 2.5 pF; The first compensator coefficient is 0.0012 per degree Celsius; The second compensator coefficient is 0.0005 per degree Celsius; Real-time steering wheel external temperature; The initial external temperature of the steering wheel was collected when the heating was started; Real-time steering wheel internal temperature; The calibration temperature is 25 degrees Celsius. This relationship allows for the use of real-time data on the plate and board temperatures collected by the NTC temperature sensor array to supplement the calibration threshold, effectively offsetting the dual interference of temperature changes and board temperature variations during heating, thus adapting to scenarios with superimposed interference after the shielding layer is removed.

[0153] Another implementation method, after incorporating ambient airflow velocity correction, ensures that the preset capacitance threshold corresponding to the heating stability scenario satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0154] in, This represents the preset capacitance threshold during the heating process, with a constraint range of 2.0pF to 2.8pF. The base threshold is set at 2.5 picofarads. The first compensator coefficient is 0.0012 per degree Celsius; The second compensator coefficient is 0.0005 per degree Celsius; The fourth compensator coefficient is 0.0002 per meter per second; Real-time steering wheel external temperature; The initial external temperature of the steering wheel was collected when the heating was started; Real-time steering wheel internal temperature; The calibration temperature is 25 degrees Celsius. This represents the real-time ambient airflow velocity.

[0155] For example, a base threshold is set. Initial plate temperature during heating start Current disk temperature Current plate temperature Ambient airflow speed Calibration temperature Then the calculation yields: .

[0156] By utilizing this relationship, real-time data on disc and plate temperatures collected by the NTC temperature sensor array, along with ambient airflow velocity data from the airflow sensor, is used to supplement and calibrate the threshold. This effectively counteracts the triple interference from temperature changes, plate temperature variations, and airflow disturbances during heating, further adapting to complex superimposed interference scenarios after the shielding layer is removed. For vehicles without airflow sensors, the airflow term can be omitted, maintaining the original compensation accuracy.

[0157] One implementation method involves a preset capacitance threshold corresponding to a stable heating scenario that satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0158] in, This represents the preset capacitance threshold under stable heating conditions. The threshold during the heating period just before entering a stable scenario; For fine-tuning, its absolute value is no greater than 0.01 pF per control cycle. The direction of fine-tuning is determined based on the rate of change of the external temperature of the steering wheel: if the temperature is stable or fluctuates slightly, The value can be 0 or a small positive / negative value. The system continuously collects temperature data through an NTC temperature sensor array, determines the temperature stability state, and fine-tunes the threshold to compensate for slight temperature drift interference during stable heating, ensuring stable judgment accuracy.

[0159] For example, a base threshold is set. The initial external temperature of the steering wheel when the heater is turned on. Current steering wheel external temperature Current steering wheel internal temperature Calibration temperature First compensator coefficient Second compensator coefficient The preset capacitance threshold during heating / in a stable heating scenario is: .

[0160] The preset capacitance threshold corresponding to the heating period scenario or heating stability scenario takes into account both the temperature rise of the steering wheel's external environment and the temperature drift of the steering wheel's internal circuitry, effectively offsetting the superimposed interference during the heating period.

[0161] Another implementation method, after incorporating ambient airflow velocity correction, ensures that the preset capacitance threshold corresponding to the heating stability scenario satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0162] in, This represents the preset capacitance threshold under stable heating conditions. The threshold during the heating period just before entering a stable scenario; This is the fourth compensator coefficient, with a value of 0.0002 per meter per second; This is the real-time ambient airflow velocity. The fine-tuning amplitude is no greater than 0.01 picofarads per control cycle to ensure smooth threshold changes.

[0163] For example, a threshold value is set for the heating period immediately before entering the heating stable scenario. Real-time ambient airflow velocity Then the calculation yields: If the ambient airflow velocity is zero, the threshold remains unchanged.

[0164] Through this relationship, the system determines the temperature stability in a heating-stable scenario by combining the steering wheel external temperature data collected by the NTC sensor array. Simultaneously, it uses real-time ambient airflow velocity data collected by the airflow sensor to make minor corrections to the threshold, effectively offsetting slight temperature drift and airflow fluctuations during stable heating, ensuring stable judgment accuracy. For vehicles without airflow sensors, the airflow term can be omitted, and the system can directly set... It maintains its original accuracy.

[0165] As one possible implementation, the threshold determination algorithm for the closed heating transition scenario is used to determine the preset capacitance threshold for the closed heating transition scenario based on the preset capacitance threshold of the heating scenario a moment before entering the closed heating transition scenario and the preset capacitance threshold of the normal unheated scenario.

[0166] One implementation method involves determining a preset capacitance threshold for a heating transition scenario that is turned off, comprising: within multiple consecutive control cycles during which the heating transition scenario is turned off, each control cycle corresponds to a preset capacitance threshold; determining the preset capacitance threshold corresponding to the heating scenario just before entering the heating transition scenario as the preset capacitance threshold of the first control cycle; the first control cycle being the first control cycle among multiple consecutive control cycles; determining the preset capacitance threshold under the normal unheated scenario as the preset capacitance threshold of the second control cycle; the second control cycle being the last control cycle among multiple consecutive control cycles; and determining the preset capacitance threshold for the heating transition scenario by progressively approaching the preset capacitance threshold of the second control cycle according to a preset gradation rule.

[0167] One implementation method involves disabling the preset capacitor threshold corresponding to the heating transition scenario, which satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0168] in, Indicates the first scene in the heating transition mode that is turned off. The preset capacitance threshold for each control cycle; The threshold is the moment before entering the transition scene (i.e., the end of the heating stable scene or the end of the scene during heating). The preset capacitance threshold (e.g., 2.3pF) is for a normal, unheated scenario. This is the current cycle number, starting from 1 and incrementing. The preset total number of transition cycles, for example, 10, corresponds to a total transition time of 500 milliseconds (50 milliseconds per control cycle) or 1000 milliseconds (100 milliseconds per control cycle). Through this linear transition relationship, combined with the residual temperature change data of the steering wheel exterior collected by the NTC sensor array, the transition speed can be dynamically adjusted (e.g., reducing the speed when the residual temperature change rate is large). (Or increase the step size) to achieve a smooth threshold transition and avoid misjudgment caused by residual changes in disk temperature.

[0169] It should be understood that the first-cycle threshold is: when hour, That is, the threshold of the first control cycle is equal to the heating scenario threshold just before entering the transition scenario. Final cycle threshold: when... hour, That is, the threshold of the last control cycle is equal to the preset capacitance threshold under normal unheated conditions. Intermediate cycle threshold: when... At that time, the threshold decreases by a fixed step size, where the step size is... For example, if the total transition time is 500ms and the control period is 50ms, then... The step size is (2.55-2.3) / 10 = 0.025pF, and the step size decreases by 0.025pF per cycle.

[0170] For example, suppose the preset capacitance threshold is 2.55pF just before entering the heating-off transition scenario (i.e., at the end of the heating-stable scenario), and the first capacitance threshold in the normal unheated scenario is 2.3pF. Then, a linear gradient is used during the transition: if the total transition time is 500ms and the control cycle is 50ms (10 cycles in total), then the threshold for the nth cycle is: .

[0171] When n=1, T=2.525pF; when n=5, T=2.425pF; when n=10, T=2.3pF. By gradually changing the preset capacitance threshold for each control cycle, a smooth transition from the heating threshold to the normal threshold is achieved, avoiding misjudgments caused by sudden threshold changes.

[0172] Another implementation involves adding an ambient airflow velocity correction and then disabling the preset capacitor threshold corresponding to the heating transition scenario, which satisfies the following threshold determination algorithm. The specific relationship is as follows:

[0173] in, Indicates the first scene in the heating transition mode that is turned off. The preset capacitance threshold for each control cycle; The heating scene threshold is set just before entering the transition scene. This is the preset capacitance threshold for a normal, unheated scenario; The current period number is incremented from 1 to... ; Set the preset total number of transition cycles (e.g., 10, corresponding to a total transition time of 500ms). The fourth compensator coefficient (airflow compensation coefficient) has a value of 0.0002 per meter per second. This represents the real-time ambient airflow velocity.

[0174] For example, suppose , , Ambient airflow speed The basic linear gradient value is not considered when airflow is neglected. After considering airflow correction: when hour, ;when hour, ;when hour, .

[0175] By combining residual plate temperature data collected by the NTC sensor array with real-time ambient airflow velocity from the airflow sensor, the gradual speed and overall threshold level are dynamically adjusted to achieve a smooth threshold transition, effectively avoiding misjudgments caused by both residual plate temperature changes and airflow disturbances. If there is no airflow sensor, the airflow term can be ignored, degenerating into a linear gradual change formula.

[0176] Another implementation method is to disable the preset capacitor threshold corresponding to the heating transition scenario, which satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0177] in, Indicates the first scene in the heating transition mode that is turned off. The preset capacitance threshold for each control cycle; The preset capacitance threshold is the value of the heating scene (either the scene during heating or the scene with stable heating) that is just before entering the transition scene. This is the preset capacitance threshold for a normal, unheated scenario; Preset gradient coefficient ( (e.g., take 0.94). This is the current cycle number, starting from 1 and incrementing, after a preset total number of gradual change cycles. After one cycle, the threshold approaches This gradual change in the index results in rapid initial changes followed by a smoother transition, allowing for selection based on the actual residual temperature characteristics of the circuit.

[0178] For example, by simulating the residual temperature change of the tray after heating is turned off at different temperature points (e.g., 25℃, 0℃, 50℃) (e.g., by controlling the temperature gradually through an environmental test chamber without airflow intervention), and combining the tray temperature data collected by the NTC sensor group (collected once every 10 milliseconds), the temperature is determined through experimental fitting. The coefficient is 0.94. This coefficient ensures a smooth transition of the capacitor signal during the compensation period, with signal fluctuations not exceeding 0.03pF, thus avoiding misjudgments of the contact status due to residual changes in plate temperature.

[0179] Another implementation method is to disable the preset capacitor threshold corresponding to the heating transition scenario, which satisfies the following threshold determination algorithm, with the specific relationship as follows:

[0180] in, Indicates the first scene in the heating transition mode that is turned off. The preset capacitance threshold for each control cycle; The preset capacitance threshold is the value corresponding to the heating scene (during heating or in a stable heating scene) just before entering the transition scene. The preset capacitance threshold (e.g., 2.5 picofarads) is for a typical unheated scenario. To preset the gradient coefficient, it adapts to different levels based on the ambient airflow velocity: normal airflow ( )hour High airflow ( )hour ; This is the current cycle number, with a value ranging from 1 to the total number of preset gradual change cycles. (For example (The corresponding total transition time is 1000 milliseconds. When the duration of the covered scene is ≤500 milliseconds, the control cycle can be adjusted accordingly.) The fourth compensator coefficient (airflow compensation coefficient) has a value of 0.0002 per meter per second. Real-time ambient airflow velocity; To calibrate the ambient airflow velocity, a value of 0 meters per second is used.

[0181] This gradual change in the index results in rapid initial changes followed by a smoother transition. The newly added airflow compensation term can offset threshold deviations caused by airflow disturbances in real time, ensuring a smooth transition without abrupt threshold changes. For example, by simulating the residual temperature change of the tray after heating is turned off at different temperature points (e.g., 25℃, 0℃, 50℃), and combining tray temperature data collected by the NTC sensor group (collected every 10 milliseconds) with airflow sensor data, experimental fitting determined that under normal airflow... Under high airflow This coefficient ensures that the capacitance signal smoothly transitions with changes in residual plate temperature and airflow disturbances during the compensation period, with signal fluctuations not exceeding 0.03 picofarads, avoiding misjudgments of the contact state caused by the combined effects of residual plate temperature changes and airflow. If there is no airflow sensor, the airflow compensation term can be ignored, and only the corresponding airflow level can be used. value.

[0182] It should be understood that by using corresponding threshold determination algorithms for different heating scenarios and dynamically calculating the preset capacitance threshold, the capacitance drift caused by factors such as temperature changes and airflow disturbances can be effectively compensated, avoiding false and false detections of hands-off detection, thereby significantly improving the accuracy and robustness of hands-off detection.

[0183] S303. Based on the compensation coefficient, the original capacitance value sensed by the heating element is compensated to determine the target capacitance value.

[0184] The compensation coefficient is determined based on the deviation between the real-time temperature of the multimodal mode and the corresponding calibration temperature.

[0185] In some embodiments, the compensation coefficients are determined based on the product of the first compensator coefficient and the deviation between the external temperature of the steering wheel and the corresponding calibration temperature, the product of the second compensator coefficient and the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature, and the product of the third compensator coefficient and the deviation between the ambient temperature and the corresponding calibration temperature.

[0186] The first compensator coefficient is greater than the second compensator coefficient, and the second compensator coefficient is greater than the third compensator coefficient. For example, the first compensator coefficient can be 0.0012 / ℃, the second compensator coefficient can be 0.0005 / ℃, and the third compensator coefficient can be 0.0003 / ℃. All calibration temperatures can be taken as 25℃.

[0187] As one possible implementation, a multimodal real-time temperature coupling compensation algorithm is invoked to fuse real-time temperature data from the NTC sensor group and the ambient temperature sensor, and to dynamically compensate and calibrate the noise-reduced capacitance signal to offset temperature variation interference in the full temperature range of -40℃ to 125℃, thereby generating an accurate target capacitance value HOD_Value.

[0188] One implementation method, specifically the formula, can be: HOD_Value = Original capacitance value × [1 + γ1 × (Steering wheel external temperature - T_cal) + γ2 × (Steering wheel internal temperature - T_cal) + γ3 × (Ambient temperature - T_cal)]. Where T_cal = 25℃ is the standard calibration temperature, and γ1 = 0.0012 / ℃ (steering wheel temperature), γ2 = 0.0005 / ℃ (PCB board temperature), and γ3 = 0.0003 / ℃ (ambient temperature) are the factory-calibrated compensation coefficients. These three coefficients work together to achieve accurate compensation across the entire temperature range. After compensation, the signal drift amplitude is less than or equal to 0.1pF, meeting automotive-grade testing accuracy requirements.

[0189] As one possible implementation method, the compensation coefficient is calculated as follows: compensation coefficient = 1 + first compensator coefficient × (steering wheel external temperature - its calibration temperature) + second compensator coefficient × (steering wheel internal temperature - its calibration temperature) + third compensator coefficient × (ambient temperature - its calibration temperature).

[0190] For example, assuming an air conditioner blowing directly on the steering wheel, the system collects the original capacitance value C_raw = 2.1pF, the external temperature of the steering wheel = 18℃, the internal temperature of the steering wheel = 20℃, the ambient temperature = 28℃, and the calibration temperature is 25℃. The compensation coefficient is taken from the example value above. Then: the external temperature deviation of the steering wheel = -7℃, contribution = 0.0012 × (-7) = -0.0084; the internal temperature deviation of the steering wheel = -5℃, contribution = 0.0005 × (-5) = -0.0025; the ambient temperature deviation = +3℃, contribution = 0.0003 × 3 = +0.0009; the compensation coefficient = 1 - 0.0084 - 0.0025 + 0.0009 = 0.99.

[0191] As one possible implementation, the target capacitance value is determined by compensating the original capacitance value sensed by the heating element based on the compensation coefficient, including: determining the target capacitance value by multiplying the original capacitance value by the compensation coefficient.

[0192] For example, continuing with the above parameters, the original capacitance value of 2.1pF is multiplied by a compensation coefficient of 0.99 to obtain a target capacitance value of 2.079pF. This value is less than 0.1pF compared to the original capacitance value, thus improving the accuracy of the hand-off detection in this application. This target capacitance value is the detection value after temperature drift is suppressed, which can be used in subsequent steps to compare with a preset capacitance threshold to determine the contact state between the driver and the steering wheel.

[0193] As one possible implementation, this application designs a multi-factor combination calibration scheme during the factory calibration stage to determine the compensation coefficients and filtering parameters. Specifically, seven temperature points are selected within the range of -40℃ to 125℃. At each temperature point, three PCB board temperature offsets relative to the disk temperature (lower by 5℃, same, higher by 5℃), three ambient temperature offsets relative to the disk temperature (lower by 10℃, same, higher by 10℃), and three ambient airflow velocities (0m / s, 3m / s, 5m / s) are set, totaling 189 operating condition combinations, comprehensively covering scenarios of temperature changes, temperature differences, and airflow interference that may occur after the shielding layer is removed. By collecting capacitance signals and temperature data under each operating condition, the first compensation coefficient, the second compensation coefficient, the third compensation coefficient, and the filtering parameters for each scenario are determined through fitting, ensuring the accuracy and robustness of off-hand detection under all operating conditions.

[0194] As one possible implementation, the original capacitance value sensed by the heating element is compensated based on a compensation coefficient. Before determining the target capacitance value, a noise reduction operation is also performed on the original capacitance value, specifically including: One implementation involves obtaining a PCB reference signal; subtracting the PCB reference signal from the original capacitance value and adding a preset calibration constant to obtain the capacitance signal after anti-interference calibration.

[0195] The PCB reference signal is generated by a reference trace on the PCB independent of the heating element. It is unaffected by driver hand contact and only reflects the electromagnetic interference and temperature drift of the circuit board itself. This step is used to counteract the effects of vehicle-mounted electromagnetic interference (such as BCI injection and high-voltage start-stop interference) on the detection channel.

[0196] One approach involves selecting a corresponding filtering method based on the current heating scenario to filter the capacitor signal after anti-interference calibration, thereby eliminating high-frequency fluctuations and signal spikes caused by temperature changes.

[0197] For example, in the scenario of direct airflow from an air conditioner, a first preset moving average filtering order (e.g., a 5-fold moving average filter with a window size of 5) is used, combined with real-time multimodal temperature data, to ensure effective suppression of high-frequency signal fluctuations caused by temperature changes, with the filtered signal fluctuation not exceeding 0.02pF. For the scenario of powering on a cold vehicle, a second-order low-pass filter (e.g., a cutoff frequency of 10Hz) is used, combined with rapid temperature rise data collected by the PCB NTC, to offset capacitor signal spike interference caused by sudden temperature changes. For scenarios of no heating, heating, or stable heating, a second preset moving average filtering order (e.g., a 3-fold moving average filter) is used. The filtered capacitor signal is used as the original capacitance value for subsequent multiplication with the compensation coefficient.

[0198] For example, assuming the current scenario is one of direct airflow from an air conditioner, the system continuously collects the capacitance value after anti-interference calibration five times, and then applies a five-fold moving average filter to it. This means the arithmetic mean of the five sampling points is used as the filtered capacitance value, effectively suppressing instantaneous fluctuations in the capacitance signal caused by direct cold airflow. This noise reduction operation makes subsequent compensation and threshold comparison more accurate, avoiding misjudgments caused by noise signals.

[0199] In summary, the external temperature of the steering wheel, the internal temperature of the steering wheel, and the ambient temperature work together to achieve accurate compensation for the drift of the capacitor signal across the entire temperature range. After compensation, the signal drift amplitude is no more than 0.1p, which meets the requirements of automotive-grade testing accuracy.

[0200] As another possible implementation, the compensation coefficient is determined based on the product of the first compensator coefficient and the deviation between the external temperature of the steering wheel and the corresponding calibration temperature, the product of the second compensator coefficient and the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature, the product of the third compensator coefficient and the deviation between the ambient temperature and the corresponding calibration temperature, and the product of the fourth compensator coefficient and the deviation between the ambient airflow speed and the corresponding calibration airflow speed.

[0201] In this system, the first compensator coefficient is greater than the second compensator coefficient, the second compensator coefficient is greater than the third compensator coefficient, and the third compensator coefficient is greater than the fourth compensator coefficient. For example, the first compensator coefficient can be taken as 0.0012 / ℃, the second compensator coefficient as 0.0005 / ℃, the third compensator coefficient as 0.0003 / ℃, and the fourth compensator coefficient as 0.0002 / (m / s). All calibration temperatures can be taken as 25℃, and the calibration airflow velocity can be taken as 0 m / s.

[0202] As one possible implementation, a multimodal real-time temperature and ambient airflow velocity coupling compensation algorithm is invoked to fuse real-time data from the NTC sensor group, ambient temperature sensor, and airflow sensor. This allows for dynamic compensation and calibration of the denoised capacitance signal, offsetting temperature variation interference across the entire temperature range of -40℃ to 125℃ and airflow disturbances within the range of 0 to 5 m / s, thereby generating a precise target capacitance value. One implementation method, specifically the formula, could be: Target capacitance value = Original capacitance value × [1 + γ1 × (Steering wheel external temperature - T_cal) + γ2 × (Steering wheel internal temperature - T_cal) + γ3 × (Ambient temperature - T_cal) + γ4 × (V_air - V_cal)]. Among them, T_cal=25℃ is the standard calibration temperature, V_cal=0m / s is the calibration airflow velocity, γ1=0.0012 / ℃, γ2=0.0005 / ℃, γ3=0.0003 / ℃, and γ4=0.0002 / (m / s) are the factory-calibrated compensation coefficients. The four factors work together to achieve accurate compensation across the entire temperature range and under airflow disturbances. After compensation, the signal drift amplitude is less than or equal to 0.1pF, which meets the automotive-grade testing accuracy requirements.

[0203] As one possible implementation method, the compensation coefficient is calculated as follows: compensation coefficient = 1 + first compensator coefficient × (steering wheel external temperature - its calibration temperature) + second compensator coefficient × (steering wheel internal temperature - its calibration temperature) + third compensator coefficient × (ambient temperature - its calibration temperature) + fourth compensator coefficient × (ambient airflow speed - its calibration airflow speed).

[0204] For example, assuming that in the scenario of direct airflow from the air conditioner, the system collects the original capacitance value C_raw=2.1pF, the external temperature of the steering wheel=18℃, the internal temperature of the steering wheel=20℃, the ambient temperature=28℃, the ambient airflow speed=4m / s, the calibration temperature is 25℃, the calibration airflow speed is 0m / s, and the compensation coefficient is taken from the example value above. Therefore: Steering wheel external temperature deviation = -7℃, contribution = 0.0012×(-7) = -0.0084; Steering wheel internal temperature deviation = -5℃, contribution = 0.0005×(-5) = -0.0025; Ambient temperature deviation = +3℃, contribution = 0.0003×3 = +0.0009; Ambient airflow speed deviation = 4m / s, contribution = 0.0002×4 = 0.0008; Compensation coefficient = 1 - 0.0084 - 0.0025 + 0.0009 + 0.0008 = 0.9908.

[0205] As one possible implementation, the target capacitance value is determined by compensating the original capacitance value sensed by the heating element based on the compensation coefficient, including: determining the target capacitance value by multiplying the original capacitance value by the compensation coefficient.

[0206] For example, continuing with the above parameters, the original capacitance value of 2.1pF is multiplied by a compensation coefficient of 0.9908 to obtain a target capacitance value of 2.08068pF. This value differs from the original capacitance value by less than 0.1pF, thus improving the accuracy of the off-hand detection in this application. This target capacitance value is the detection value after temperature drift and airflow disturbance are suppressed, and can be used in subsequent steps to compare with a preset capacitance threshold to determine the contact state between the driver and the steering wheel.

[0207] As one possible implementation, this application designs a multi-factor combination calibration scheme during the factory calibration stage to determine the compensation coefficients and filtering parameters. Specifically, at seven temperature points—-40℃, -20℃, 0℃, 25℃, 50℃, 85℃, and 125℃—three PCB board temperature offsets relative to the disk temperature (5℃ lower, the same, and 5℃ higher), three ambient temperature offsets relative to the disk temperature (10℃ lower, the same, and 10℃ higher), and four ambient airflow velocities (0m / s, 2m / s, 3m / s, and 5m / s) are set for each temperature point, totaling 7×3×3×4=252 operating condition combinations. This comprehensively covers scenarios involving temperature changes, temperature differences, and airflow interference that may occur after the shielding layer is removed. By collecting capacitance signals and temperature data under each operating condition, the first, second, third, and fourth compensation coefficients, as well as the filtering parameters for each scenario, are fitted and determined to ensure the accuracy and robustness of off-hand detection under all operating conditions.

[0208] As one possible implementation, the original capacitance value sensed by the heating element is compensated based on a compensation coefficient. Before determining the target capacitance value, a noise reduction operation is performed on the original capacitance value. Specifically, this includes: acquiring a PCB reference signal; subtracting the PCB reference signal from the original capacitance value and adding a preset calibration constant to obtain an anti-interference calibrated capacitance signal. The PCB reference signal is generated by a reference trace on the PCB board independent of the heating element, and is unaffected by driver hand contact, reflecting only the electromagnetic interference and temperature drift of the circuit board itself. This step is used to counteract the influence of vehicle-mounted electromagnetic interference (such as BCI injection and high-voltage start-stop interference) on the detection channel.

[0209] One implementation involves selecting a corresponding filtering method based on the current heating scenario and ambient airflow velocity to filter the capacitor signal after anti-interference calibration, thereby eliminating high-frequency fluctuations and signal spikes caused by temperature changes and airflow.

[0210] For example, in a scenario where the air conditioner blows directly on the air: when the ambient airflow velocity is within the normal range (2m / s ≤ V_air < ​​3m / s), a 5-fold moving average filter is used (window size set to 5); when the ambient airflow velocity is high (V_air ≥ 3m / s), a 7-fold moving average filter is used (window size set to 7). By combining the temperature difference data from the NTC sensor group and the ambient temperature sensor, as well as the ambient airflow velocity data, high-frequency signal fluctuations caused by the superposition of temperature changes and airflow are effectively suppressed, and the signal fluctuation after filtering is no greater than 0.015pF.

[0211] For cold start scenarios: when the ambient airflow speed is less than 3m / s, a second-order low-pass filter is used. When the ambient airflow speed is ≥3m / s, the cutoff frequency is set to 10Hz. Combined with the rapid temperature rise data collected by the PCB NTC and the airflow sensor data, the capacitor signal spike interference caused by sudden temperature changes and airflow disturbances is offset.

[0212] For both unheated and stable heating scenarios: when the ambient airflow velocity is less than 2 m / s, a 3-fold moving average filter (window size set to 3) is used; when the ambient airflow velocity is ≥ 2 m / s, a 5-fold moving average filter (window size set to 5) is used. This combines stable temperature data collected by the NTC sensor array with airflow sensor data to suppress slight temperature drift and airflow disturbance interference while ensuring detection response speed. The filtered capacitance signal is used as the original capacitance value for subsequent multiplication with the compensation coefficient.

[0213] For example, assuming a scenario of direct airflow from an air conditioner with an ambient airflow velocity of 3 m / s (high airflow), the system continuously collects the capacitance value after anti-interference calibration seven times and applies a seven-fold moving average filter to it. This means the arithmetic mean of the seven sampling points is used as the filtered capacitance value, effectively suppressing instantaneous fluctuations in the capacitance signal caused by strong direct airflow. This noise reduction operation makes subsequent compensation and threshold comparison more accurate, avoiding misjudgments caused by noise signals.

[0214] Based on S303, this embodiment utilizes the combined effects of the steering wheel's external temperature, internal temperature, ambient temperature, and ambient airflow speed to achieve precise compensation for capacitor signal drift across the entire temperature range and under airflow disturbances. After compensation, the signal drift amplitude is no greater than 0.1pF, and after filtering, the signal fluctuation is no greater than 0.015pF, meeting automotive-grade testing accuracy requirements.

[0215] S304. Compare the target capacitance value with the preset capacitance threshold corresponding to the heating scenario, and determine the contact state between the driver and the steering wheel based on the comparison result.

[0216] In some embodiments, the target capacitance value is compared with a preset capacitance threshold corresponding to the heating scenario, and the contact state between the driver and the steering wheel is determined based on the comparison result, including: (1) When the target capacitance value is greater than or equal to the first capacitance threshold, the contact state is determined to be the grip state.

[0217] For example, when the capacitance detection value is high, it indicates that the driver's hands are in close contact with and gripping the steering wheel, thus indicating a gripping signal. For instance, in a normal heating scenario, the first capacitance threshold can be set to 2.3pF. If the target capacitance value reaches or exceeds this value, a gripping signal is output, indicating that the driver is effectively controlling the steering wheel and the driver assistance function can continue to be maintained.

[0218] (2) When the target capacitance value is less than the first capacitance threshold and greater than or equal to the second capacitance threshold, the contact state is determined to be the touch state.

[0219] The preset capacitance threshold includes a first capacitance threshold and a second capacitance threshold; the first capacitance threshold is greater than the second capacitance threshold.

[0220] In one implementation, the second capacitance threshold is a preset multiple of the first capacitance threshold, with the multiple ranging from 0 to 1, for example, 0.8. Using a proportional threshold configuration allows for a reasonable division of the intermediate range between the grip and touch states, ensuring uniform and reasonable boundary divisions for different contact states and avoiding frequent state jumps caused by excessively narrow threshold ranges. Simultaneously, the proportional threshold configuration can adapt to the capacitance value changes after temperature compensation in various scenarios, improving the stability and robustness of contact state classification and reducing misidentification issues during operating condition switching. For example, when the first capacitance threshold is 2.5pF, the second capacitance threshold is 2.0pF, forming a 0.5pF touch state range between them.

[0221] For example, when the target capacitance value is in the middle range between the first capacitance threshold and the second capacitance threshold, it means that the driver's hand is only slightly touching the steering wheel, the contact area is small, and the capacitance increase is limited, which is judged as a steering wheel touch transition state. In this state, other signals (such as EPS torque) can be further combined for auxiliary judgment to confirm the driver's actual driving intention.

[0222] In other embodiments, the comparison of the target capacitance value with a preset capacitance threshold corresponding to the heating scenario, and the determination of the driver's contact state with the steering wheel based on the comparison result, further includes a graded adaptation determination based on real-time ambient airflow velocity. Specifically, let the dynamic threshold for the current scenario adaptation be... The real-time ambient airflow velocity is airflow change rate .

[0223] One implementation method is when the target capacitance value is greater than or equal to At that time, if there is no sudden change in the ambient airflow velocity ( If it is in a high airflow scenario, it is directly determined to be in a gripping state; And the target capacitance value is slightly higher than the threshold. If so, an additional preset control cycle is performed to avoid misjudgments caused by airflow disturbances.

[0224] One implementation method is to use a method where the target capacitance value is within the range of the sample plate ( When it is a normal airflow ( If it is a high-airflow scenario, it is directly determined to be in the state of palletizing; if it is a high-airflow scenario ( If so, it is necessary to further confirm that the airflow is stable. Then it is determined to be in the state of "touching the board".

[0225] One implementation method is when the target capacitance value is less than If the airflow data is normal (no sudden airflow disturbances), If this state continues for a preset release duration (e.g., 2 control cycles, or 200ms), it is determined to be a release state; if it is in a high airflow scenario ( If the judgment duration is extended to 3 control cycles (300ms), the misjudgment caused by airflow disturbance will be further suppressed.

[0226] It should be understood that, by introducing graded adaptation of ambient airflow velocity in this embodiment, this application can maintain high accuracy and robustness of off-hand detection under conditions with airflow interference, such as direct airflow from an air conditioner. In some embodiments, please refer to... Figure 4 , Figure 4 This is a flowchart illustrating a method for detecting hand-off detection during a touch test, as provided in an embodiment of this application. Specifically, it includes: S401. After confirming that the contact state is the pallet state, collect the vehicle torque sensor value.

[0227] The vehicle torque sensor value refers to the torsional torque applied by the driver to the steering column through the steering wheel, measured in Newton-meters (N·m). This value reflects whether the driver actively controls the steering wheel. When the driver only lightly touches the steering wheel (touch-the-wheel state), no steering force may be applied; however, when the driver actually grips the wheel and prepares to turn, a measurable torque is generated.

[0228] In one possible implementation, the torque sensing value is measured by a torque sensor in the electric power steering (EPS) system. This sensor is typically mounted on the steering column torsion bar and converts the torque into a voltage signal using magnetoresistive or strain gauge principles. This signal is then processed into a digital quantity (e.g., 0.1 N·m resolution) by the EPS controller and transmitted via a CAN or LIN bus to the domain controller or the microprocessor chip described in this application. The microprocessor chip receives this torque value via a CAN / LIN transceiver for further decision-making.

[0229] S402. When the torque sensing value is greater than or equal to the first torque threshold, the contact state is corrected from the touch state to the grip state.

[0230] For example, the first torque threshold can be 0.5 N·m. For instance, if the EPS torque value is read as 0.7 N·m while in a tactile feedback state, which is greater than or equal to 0.5 N·m, it indicates that although the driver's capacitance signal is within the tactile feedback range, they are actually turning the steering wheel and have a clear intention to control it. Therefore, the contact state is corrected to gripping the wheel to avoid misinterpreting a slightly low capacitance signal as a loss of control or triggering unnecessary alarms.

[0231] S403. When the torque sensing value is less than the first torque threshold and the rate of change of any real-time temperature in the multi-modal real-time temperature is greater than the corresponding preset temperature stability threshold, the contact state is re-determined after a preset control cycle.

[0232] One of the preset control cycles is any one of the multiple continuous control cycles in the current heating scenario.

[0233] As one possible implementation, the aforementioned "corresponding preset temperature stability threshold" varies depending on the current heating scenario. Specifically, it includes: if the current scenario is a direct air conditioning blowing scenario, the temperature change rate parameter is the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature, and the corresponding preset temperature stability threshold is the first preset temperature difference threshold (e.g., 5℃); if the current scenario is a cold start scenario, the temperature change rate parameter is the rate of change of the internal temperature of the steering wheel, and the corresponding preset temperature stability threshold is the second rate of change threshold (e.g., 0.5℃ / 100ms); if the current scenario is during heating, the temperature change rate parameter is the rate of change of the external temperature of the steering wheel, and the corresponding preset temperature stability threshold is the first preset steering wheel temperature change rate threshold (e.g., 0.3℃ / 100ms); if the current scenario is a transition scenario where heating is turned off, the temperature change rate parameter is the residual rate of change of the external temperature of the steering wheel, and the corresponding preset temperature stability threshold is the preset residual rate of change threshold (e.g., 0.1℃ / 100ms).

[0234] When the temperature change rate parameter is greater than the preset temperature stability threshold of the corresponding scenario, it is determined that there is a risk of signal drift. At this time, the contact status is not output immediately, but the contact status determination of S304 is re-executed after a preset control cycle (e.g., 100 milliseconds).

[0235] For example, assuming the current scenario is during heating, the preset temperature stability threshold (first preset steering wheel temperature change rate threshold) is 0.3℃ / 100ms. If the external temperature change rate of the steering wheel is 0.4℃ / 100ms, exceeding this threshold, the system will delay for one control cycle (100ms) and then re-determine the contact state to avoid misjudgment caused by capacitance signal drift due to drastic temperature changes.

[0236] S404. When the rate of change of the real-time temperature of the multimodal modes is less than or equal to the corresponding preset temperature stability threshold, the contact state is directly determined to be the plate-touch state.

[0237] Here, the "multimodal real-time temperature change rate" and the "corresponding preset temperature stability threshold" are defined according to the different heating scenarios in S403: for example, in the air conditioning direct blowing scenario, the absolute value of the difference between the steering wheel external temperature and the ambient temperature is compared with the first preset temperature difference threshold; in the cold start power-on scenario, the change rate of the steering wheel internal temperature is compared with the second change rate threshold; in the heating period scenario, the change rate of the steering wheel external temperature is compared with the first preset steering wheel temperature change rate threshold; in the heating off transition scenario, the residual change rate of the steering wheel external temperature is compared with the preset residual change rate threshold.

[0238] For example, assuming the current scenario is a normal, unheated scenario (a steady-state scenario without heating interference), the torque sensing value is 0.2 N·m (less than the first torque threshold of 0.5 N·m), and the external temperature change rate of the steering wheel is 0.1℃ / 100ms, the internal temperature change rate of the steering wheel is 0.05℃ / 100ms, and the ambient temperature change rate is 0.02℃ / 100ms. All the change rates do not exceed the preset temperature stability threshold corresponding to their respective scenarios (for example, the threshold of 0.3℃ / 100ms for the heated stable scenario can be used for the normal, unheated scenario). In this case, the system directly determines the contact state as the steering wheel touching state and outputs this state for subsequent decision-making.

[0239] Based on S401 to S404, this application introduces torque sensing values ​​and multimodal real-time temperature change rates for auxiliary decision-making during the hand-on state: when the torque sensing value reaches a first torque threshold, the hand-on state is corrected to a grip state, reflecting the actual control intention; when the torque is insufficient but the temperature changes drastically, a re-determination is performed after a one-control-cycle delay to avoid misjudgments caused by temperature drift; when the torque is insufficient and the temperature is stable, the hand-on state is directly output. This mechanism significantly improves the robustness and accuracy of off-hand detection in critical states and temperature-changing scenarios.

[0240] (3) If the duration of the target capacitance value being less than the second capacitance threshold reaches the preset release duration, the contact state is determined to be the release state.

[0241] For example, the system is only determined to be in a hands-free state when the target capacitance value remains consistently below the second capacitance threshold for a certain duration (e.g., 200 milliseconds). Setting a preset hands-free duration can effectively prevent misjudgments caused by instantaneous signal fluctuations (such as the driver briefly releasing their finger or capacitance noise caused by road bumps). If the low capacitance state lasts for less than the preset duration, the system maintains its original state, thereby improving the reliability and anti-interference capability of hands-free detection.

[0242] In summary (1)-(3), this application subdivides the contact state into three types: holding the plate, touching the plate, and releasing the hand by setting a first capacitance threshold and a second capacitance threshold. It also introduces a proportional threshold configuration and a release confirmation time to achieve hierarchical and accurate identification of the contact state, effectively avoiding misjudgment caused by frequent state jumps and instantaneous interference, and improving the stability and reliability of release detection.

[0243] In other embodiments, based on Figure 4 The hand-off detection method shown in the diagram further incorporates ambient airflow velocity as an auxiliary factor to address operating conditions with airflow interference, such as direct airflow from an air conditioner. Specifically, while executing steps S401 to S404, real-time ambient airflow velocity is collected via an airflow sensor. and its rate of change And use it as a supplementary decision parameter.

[0244] In one implementation, when the torque sensing value is less than a first torque threshold and the temperature change rate does not exceed a preset temperature stability threshold for the corresponding scenario, the system enters an airflow stability auxiliary assessment, including: If the current scenario involves direct airflow from an air conditioner and the ambient airflow speed is... Meanwhile, the rate of change of temperature difference or airflow mutation rate If the signal drift risk is detected, the contact status will be reassessed after a preset control cycle.

[0245] If the current scenario is during heating, and the ambient airflow speed is... Meanwhile, the rate of change of disk temperature If so, the re-judgment will also be delayed.

[0246] If the current scenario is a cold start-up, and the ambient airflow speed is... Meanwhile, plate temperature change rate If so, the re-judgment will be delayed.

[0247] If all temperature change rates are less than or equal to the corresponding threshold, and the airflow is stable ( If ), then the pan status will be output directly.

[0248] In the decision output stage, when the torque sensor value is greater than or equal to the first torque threshold, it is directly corrected to the grip state under normal airflow conditions; if it is a high airflow scenario ( Then the required torque value is... This is to counteract minor fluctuations in the torque signal caused by airflow disturbances. If the airflow is unstable for two consecutive control cycles ( If the signal continues to exceed the threshold of the corresponding scenario, the system will trigger a re-acquisition of the signal and re-execute the temperature-gas coupling compensation calibration.

[0249] It should be understood that, in the generation of status messages, in addition to the three-dimensional status signal, detection value, and sub-scene identifier, real-time environmental airflow velocity and airflow change rate fields are also added, providing complete operating condition data support for the intelligent driving controller. Through the above-mentioned hierarchical adaptation and fuzzy adjudication based on environmental airflow velocity, this application effectively suppresses misjudgments in scenarios with airflow interference, such as direct airflow from the air conditioner, further improving robustness and safety under all operating conditions.

[0250] As one possible embodiment, the steering wheel off-hand detection method further includes: in a heating scenario, sequentially executing a heating duration, a switching protection duration, and a capacitor detection duration within each preset control cycle; each preset control cycle is any one of multiple consecutive control cycles during the heating scenario; wherein, the heating duration is the preset control cycle minus the sum of the switching protection duration and the capacitor detection duration; the heating duration is determined based on the difference between the external temperature of the steering wheel and a preset target temperature; the preset target temperature is determined based on the driver's needs.

[0251] As one possible implementation, the heating scenario is a heating period scenario. In this scenario, the dynamic heating duration, the preset switching protection duration, and the preset capacitor detection duration are executed sequentially within each preset control cycle. The dynamic heating duration is dynamically calculated using a PID algorithm based on the difference between the external temperature of the steering wheel and the preset target temperature, and the sum of the dynamic heating duration, the preset switching protection duration, and the preset capacitor detection duration is equal to the preset control cycle.

[0252] One implementation method, based on the PID algorithm, satisfies the following relationship:

[0253] in, Indicates the dynamic heating duration; , , These are the factory calibration coefficients; The target temperature set by the user; The system collects the external temperature of the steering wheel in real time. One implementation involves setting the PID coefficients at three target temperatures of 28℃, 38℃, and 50℃ at a normal temperature of 25℃. Under different wheel temperature scenarios, the values ​​are determined through multiple temperature increase experiments and by fitting the wheel temperature data collected by the NTC sensor group.

[0254] For example, suppose the preset control cycle is 100 milliseconds, the preset switching protection time is 1 millisecond, and the preset capacitor detection time is 10 milliseconds. Based on the PID algorithm, the current dynamic heating time is calculated to be 65 milliseconds (determined by the difference between the steering wheel's external temperature and the preset target temperature of 38°C). Then, the timing sequence for each control cycle is: heating 65 milliseconds → switching protection 1 millisecond → capacitor detection 10 milliseconds, with the remaining 24 milliseconds being idle time (which can be ignored). This dynamic adjustment ensures a balance between heating efficiency and detection accuracy.

[0255] For example, suppose the user sets a target temperature Real-time monitoring of the external temperature of the steering wheel (In the initial heating phase, the temperature change rate meets the requirements of the heating scenario), integral term (A total of 10 control cycles, each cycle 100ms), differential term (The plate temperature rises at a constant rate). Substitute this into the PID formula (take...) ): Since the calculated result (99.04ms) exceeds the maximum allowable heating time (89ms, i.e., 100-1-10), the system uses the upper limit. The timing sequence at this point is: heating 89ms → protection switching 1ms → capacitor detection 10ms, with no idle time.

[0256] If If adjusted to 0.8 (this is only to demonstrate the effect of a small scaling factor), then: The result satisfies the constraint of ≤89ms, with the timing sequence as follows: heating 23.44ms → protection 1ms → detection 10ms → idle 65.56ms. In this case, the system achieves temperature rise with a relatively low heating duty cycle while ensuring the detection time (10ms). In practical applications, the PID coefficients are factory calibrated (…). This can provide a faster response, while the low here This is for comparison purposes only.

[0257] Regardless of the parameters used, both the NTC sensor and the ambient temperature sensor need to acquire data at high frequency to provide real-time support for capacitor calibration and dynamic adjustment of heating time.

[0258] Another implementation method is based on the following relationship between the PID algorithm and the airflow correction term:

[0259] in, Indicates the dynamic heating duration; , , The PID coefficients are factory calibrated. This is the airflow correction factor; The target temperature set by the user ranges from 28℃ to 50℃. The steering wheel external temperature is collected in real time; This refers to the real-time ambient airflow velocity. One implementation method involves setting the PID coefficient at three target temperatures of 28℃, 38℃, and 50℃ at a normal temperature of 25℃, and superimposing four levels of ambient airflow velocity of 0m / s, 2m / s, 3m / s, and 5m / s respectively. Through multiple temperature increase experiments under different disk temperature scenarios, combined with disk temperature data collected by the NTC sensor group and airflow sensor data, the PID coefficient and airflow correction coefficient are determined by multiple linear regression fitting.

[0260] For example, the preset control cycle is set to 100 milliseconds, the preset switching protection duration is 1 millisecond, the preset capacitor detection duration is 10 milliseconds, and the maximum allowable heating duration is 89 milliseconds. The current dynamic heating duration is calculated using a PID algorithm with airflow correction, and is determined based on the difference between the external temperature of the steering wheel and the preset target temperature, as well as the real-time ambient airflow speed.

[0261] For example, suppose the user sets a target temperature Real-time monitoring of the external temperature of the steering wheel (In the initial heating phase, the temperature change rate meets the requirements of the heating scenario), integral term (A total of 10 control cycles, each cycle 100ms), differential term (Disk temperature rises at a constant rate), real-time ambient airflow velocity Substituting into the PID formula with airflow correction: Since the calculated result (97.04ms) exceeds the maximum allowable heating time (89ms), the system uses the upper limit. The timing sequence at this point is: heating 89ms → protection switching 1ms → capacitor detection 10ms, with no idle time.

[0262] If the real-time ambient airflow speed If other parameters remain unchanged, then: It still exceeds the 89ms limit, so we'll use 89ms. If we... Adjusted to 0.8 (only to demonstrate the effect of a smaller scaling factor combined with low to medium airflow). ,but: .

[0263] The result meets the ≤89ms constraint, with the timing sequence as follows: heating 22.44ms → protection 1ms → detection 10ms → idle 66.56ms. In practical applications, the PID coefficients are factory calibrated (…). Combined with airflow correction, it can provide better response and resistance to airflow interference. This is for comparison purposes only.

[0264] Regardless of the parameters used, the NTC sensor, ambient temperature sensor, and airflow sensor all need to acquire data at high frequency to provide real-time support for capacitance calibration and dynamic adjustment of heating time, effectively suppressing the impact of temperature change and airflow interference on heating efficiency and detection accuracy.

[0265] As one possible implementation, the heating scenario is a stable heating scenario. In this scenario, a fixed heating duration, a preset switching protection duration, and a preset capacitor detection duration are executed sequentially within each preset control cycle; the fixed heating duration is the preset control cycle minus the difference between the preset switching protection duration and the preset capacitor detection duration, and the fixed heating duration remains unchanged.

[0266] For example, suppose the preset control cycle is 100 milliseconds, the preset switching protection time is 1 millisecond, and the preset capacitor detection time is 10 milliseconds. The fixed heating time is 100 - 1 - 10 = 89 milliseconds. Then the timing of each control cycle is fixed as follows: heating 89 milliseconds → switching protection 1 millisecond → capacitor detection 10 milliseconds. This fixed duty cycle maintains the steering wheel temperature stable near the preset target value.

[0267] For example, when the scene is identified as a heating-stable scene, the NTC sensor collects the rate of change of the external temperature of the steering wheel. The temperature change rate is less than or equal to the first preset plate temperature change rate threshold (0.3℃ / 100ms), and this state lasts for 600ms (exceeding the preset stabilization time of 500ms). The user sets the target temperature. Current steering wheel external temperature The temperature has stabilized. Substituting the fixed-duty-cycle calculation logic: a preset control cycle of 100ms, a protection switching duration of 1ms, and a capacitor detection duration of 10ms, the fixed heating duration = 100 - 1 - 10 = 89ms. The timing sequence is fixed as follows: heating 89ms → protection switching 1ms → capacitor detection 10ms. This fixed duty cycle can maintain the external temperature of the steering wheel within a stable range of 37.8℃ ± 0.2℃ without dynamic adjustment. The NTC sensor group continuously collects external and internal temperature data of the steering wheel to determine the temperature stability; if the temperature change rate exceeds the threshold, a scene switch is triggered (e.g., switching back to the heating scene), and the time-division multiplexing duration is recalculated.

[0268] As another possible implementation, considering the impact of ambient airflow velocity on the heating stability scenario, this application performs hierarchical adaptation of the time-sharing scheduling sequence, as follows: In a stable heating scenario, a fixed heating duration, a preset switching protection duration (1 ms), and a preset capacitor detection duration are executed sequentially within each preset control cycle (100 ms). The fixed heating duration and capacitor detection duration are determined based on the real-time ambient airflow velocity. Hierarchical settings: When the ambient airflow speed During (normal airflow) operation, the capacitor detection time is 10 milliseconds, and the fixed heating time is 100-1-10=89 milliseconds. The timing sequence is: heating for 89 milliseconds → switching protection for 1 millisecond → capacitor detection for 10 milliseconds.

[0269] When the ambient airflow speed During high airflow, the capacitor detection time is extended to 12 milliseconds to enhance the ability to resist airflow disturbances. The fixed heating time is 100-1-12=87 milliseconds, and the timing sequence is: heating for 87 milliseconds → switching protection for 1 millisecond → capacitor detection for 12 milliseconds.

[0270] Meanwhile, the duration threshold for a stable heating state in high airflow scenarios has been extended from the usual 500 milliseconds to 700 milliseconds to avoid misjudging scenarios as heating periods due to instantaneous airflow fluctuations. The NTC sensor array continuously collects external and internal temperature data for the steering wheel, while the airflow sensor simultaneously collects real-time ambient airflow velocity and airflow change rate. This is used to determine the overall stability of temperature and airflow. If the temperature change rate exceeds the first preset plate temperature change rate threshold (0.3℃ / 100ms), or the airflow change rate exceeds the preset airflow stability threshold (e.g., ... If this occurs, a scene switch is triggered (e.g., switching back to the scene during heating), and the time-sharing reuse duration is recalculated.

[0271] For example, suppose the user sets a target temperature Current steering wheel external temperature (The airflow velocity has stabilized) Real-time ambient airflow velocity (High airflow). The NTC sensor collected the plate temperature change rate. This state lasted for 700 ms; the airflow sensor detected that the ambient airflow velocity remained stable within the range of 3.5 ± 0.3 m / s, with a change rate of... The system then determines the scenario as a high-airflow heating stability scenario and adopts a high-airflow timing sequence: heating 87 milliseconds → protection switching 1 millisecond → capacitor detection 12 milliseconds. This fixed duty cycle can maintain the steering wheel's external temperature within the range of 37.8℃±0.2℃, while effectively suppressing the interference of airflow disturbances on capacitor detection.

[0272] If the ambient airflow speed drops to If the temperature change rate or airflow change rate exceeds the corresponding stability threshold, the scene switch is automatically triggered, and the time-division multiplexing duration is recalculated. Through this airflow graded adaptation mechanism, this application ensures both temperature stability and enhanced resistance to airflow interference in heating stable scenarios.

[0273] As another possible implementation, in a heating stability scenario, the preset capacitance threshold is the same as the threshold used during the heating period. In conjunction with the external temperature data of the steering wheel collected by the NTC sensor array, minor adjustments are made in each control cycle. Specifically, the preset capacitance threshold for the heating stabilization scenario is... Determine according to the following fine-tuning formula:

[0274] in, It is the difference between the external temperature of the steering wheel in the current control cycle and the previous control cycle (its absolute value is not greater than 0.2℃). This is a preset fine-tuning coefficient (e.g., 0.001 per degree Celsius, factory calibrated). This fine-tuning amount does not exceed 0.01 pF per cycle to ensure that the threshold changes smoothly and does not affect the judgment accuracy.

[0275] This implementation method monitors the stability of the external temperature of the steering wheel in real time, triggers threshold fine-tuning, maintains a stable match between the detection capacitance value and the preset capacitance threshold, counteracts slight temperature drift interference, and ensures that the heat preservation effect and detection function do not conflict, meeting the requirement of consistent accuracy in all scenarios.

[0276] As one possible implementation, the heating scenario is a non-heating scenario (including direct air conditioning blowing scenario, cold engine power-on scenario, and regular non-heating scenario). In this scenario, the heating time is zero, and the capacitance detection time occupies the entire preset control cycle, requiring no time-sharing scheduling. The heating element acts as the capacitance sensing electrode throughout the entire process. The capacitance sensing chip acquires signals at a frequency of 50Hz, with a sampling frequency no lower than 50Hz and a single detection time not exceeding 20ms. For the cold engine power-on scenario and the direct air conditioning blowing scenario, the NTC sensor group and the ambient temperature sensor are synchronously upgraded to a high-frequency acquisition of 50Hz; for the regular non-heating scenario, it is acquired at a regular 10Hz, with the filtering method and noise reduction algorithm being consistent.

[0277] For example, in the unheated scenario, the heating time is 0 milliseconds, and the capacitance detection time occupies the entire preset control cycle (e.g., 100 milliseconds), eliminating the need for switching protection. The heating element acts as a capacitance sensing electrode around the clock, detecting driver hand contact with the highest sensitivity.

[0278] As another possible implementation, the heating scenarios are the air conditioning direct blowing scenario, the cold car power-on scenario, and the normal unheated scenario. For the normal unheated scenario, it is finely adjusted once every 1 second to counteract slight temperature drift and airflow disturbance.

[0279] As one possible implementation, the heating scenario is a heating-off transition scenario. In this scenario, the heating duration is zero, the capacitance detection duration is extended to a value greater than the preset capacitance detection duration (e.g., 15 milliseconds), and no switching protection duration is set within the preset control cycle to improve signal acquisition accuracy, while also incorporating threshold gradient rules.

[0280] For example, in a scenario where heating is turned off during transition: assuming the preset control cycle remains 100 milliseconds and the heating duration is 0 milliseconds, the capacitance detection duration is extended to 15 milliseconds (5 milliseconds longer than the normal detection duration of 10 milliseconds), without needing to switch protection. The remaining 85 milliseconds are idle time. This extended detection duration configuration improves the accuracy of signal acquisition during the residual temperature change stage, helping to achieve a smooth transition in conjunction with threshold gradient rules.

[0281] It should be understood that the steering wheel off-hand detection method provided in this application has the advantage of high detection accuracy. Testing shows that the accuracy rate of off-hand detection is no less than 98.5% under all operating conditions. In four interference scenarios after removing the shielding layer (including direct air conditioning blowing, cold start, heating period, and transition after heating is turned off), the capacitor signal drift is no greater than 0.1pF, and the false judgment rate is no more than 0.3%, fully meeting automotive-grade safety requirements.

[0282] As another possible implementation, taking into account the ambient airflow velocity, the time-sharing scheduling and signal processing for shutting down the heating transition scenario are further optimized as follows: In this scenario, the heating time is zero, the preset control cycle remains unchanged at 100 milliseconds, and the capacitor detection time is extended in stages based on the real-time ambient airflow speed. Specifically, when the airflow speed... (For normal airflow) the capacitance detection time is extended to 15 milliseconds; when (High airflow) The capacitance detection time is extended to 18 milliseconds. By increasing the detection time, the signal acquisition accuracy is improved under the superposition of residual temperature change and airflow disturbance, thus offsetting the interference from both residual heating temperature change and airflow.

[0283] Meanwhile, a first-order low-pass filter is used to smooth the transition of the capacitor signal, and the filter cutoff frequency is adapted to the airflow level: conventional airflow ( The cutoff frequency is set to 8Hz during high airflow. The cutoff frequency is set to 6Hz. The NTC sensor group continuously collects data on residual temperature changes outside the steering wheel at a high frequency of 50Hz, while the airflow sensor simultaneously collects real-time airflow velocity and airflow change rate at a high frequency. This provides data support for algorithm compensation and threshold gradual change.

[0284] It should be understood that the steering wheel off-hand detection method provided in this application has the advantage of high detection accuracy. Testing shows that the accuracy rate of off-hand detection is no less than 98.5% under all operating conditions. In four interference scenarios after removing the shielding layer (including direct air conditioning blowing, cold start, heating period, and transition after heating is turned off), the capacitor signal drift is no greater than 0.1pF, and the false judgment rate is no more than 0.3%, fully meeting automotive-grade safety requirements.

[0285] In summary, for example, please refer to Figure 5As shown, the time-sharing timing sequence of the steering wheel hands-off detection method provided in this application is presented. Using a preset control cycle (e.g., 100 milliseconds) as the unit, differentiated timing configurations are designed for three operating conditions: heating period scenario, heating stability scenario, and heating-off transition scenario, to achieve staggered and coordinated operation of heating duration and capacitor detection duration: In the heating period scenario, capacitor detection is maintained on from 0ms to 60ms, followed by heating being turned off from 60ms to 66ms. After a switching protection period of 60ms to 70ms, capacitor detection and idle processing are completed in the 70ms to 100ms period. In the heating stability scenario, a fixed heating duration is executed from 0ms to 80ms, with 80ms to 90ms reserved as a switching protection period, and capacitor detection is performed for 10 milliseconds from 90ms to 100ms. In the heating-off transition scenario, the capacitor detection duration is extended from 0ms to 15ms, heating is turned off from 15ms to 100ms, and the transition from 0ms to 100ms gradually eliminates heat generation. By employing time-division multiplexing and protection interval design, the impact of heating interference on capacitance detection is effectively avoided, thereby improving the stability of off-hand detection under all operating conditions.

[0286] As one possible embodiment, the contact state includes the gripping state, the touching state, and the hands-off state; the steering wheel hands-off detection method further includes: When the contact state is determined to be a hands-free state, the current vehicle speed is greater than or equal to a preset speed threshold, and the duration of hands-free operation is less than or equal to the first warning duration, a level one alarm is triggered. The level one alarm is used to indicate the instrument panel warning.

[0287] For example, the preset vehicle speed threshold is set to 60 kilometers per hour, and the first warning duration is 15 seconds. When the system determines that the contact state is a hands-free state, the current vehicle speed is 80 kilometers per hour, and the hands-free duration reaches 15 seconds, a level one alarm is triggered, and the instrument panel displays an optical warning (e.g., a flashing yellow steering wheel icon).

[0288] If no effective response from the driver is detected after the first-level alarm is triggered, and the duration of the hands-off operation is less than or equal to the second warning duration, a second-level alarm is triggered. The second-level alarm is used to indicate the instrument panel and sound an alarm.

[0289] For example, the duration of the second warning is set to 30 seconds. If the driver does not hold the steering wheel after the first warning is triggered, and the time the driver has not held the steering wheel for 30 seconds reaches the second warning, the instrument panel will simultaneously display a red steering wheel icon and emit a beeping alarm sound.

[0290] If no effective response from the driver is detected after the Level 2 alarm is triggered, and the driver is hands-free for a duration that reaches the third preset warning duration, a Level 3 warning will be triggered. The Level 3 warning is used to indicate that the driver assistance function is disengaged and a preset risk response strategy will be activated.

[0291] For example, the third preset warning duration is set to 60 seconds (accumulated from the start of the hands-free period). If the driver still does not respond after the second-level alarm is triggered and the hands-free period reaches 60 seconds, the third-level warning is triggered, the system executes the exit of the assisted driving function and initiates the preset risk response strategy (such as active deceleration, activation of hazard lights, and request for driver takeover).

[0292] When the temperature drift of the target capacitor value exceeds the preset drift tolerance threshold and the duration of the abnormal state reaches the preset fault confirmation duration, the combined driving assistance function is disabled within the preset penalty duration.

[0293] For example, the preset drift tolerance threshold is set to 0.05pF, the preset fault confirmation time is 5 seconds, and the preset penalty time is 30 minutes. When the system detects that the temperature drift of the target capacitance value exceeds 0.05pF for 5 consecutive seconds, it determines that the system parameters are abnormal and disables the combined driving assistance function for the next 30 minutes until the fault is cleared or the vehicle restarts and passes the self-test.

[0294] In summary, as Figure 6 The diagram illustrates the workflow of the steering wheel hands-off detection method provided in this application embodiment, including: after the vehicle is powered on, the sensor group collects the external temperature and internal temperature of the steering wheel in real time, detects the ambient temperature in real time, or collects the ambient airflow speed in real time (using dashed boxes); the hardware PCB board temperature sensing circuit detects the internal temperature of the steering wheel in real time, and the microprocessor temperature circuit collects the chip temperature in real time; after the integrated HOD hands-off detection module completes initialization, it starts the dynamic adaptive intelligent detection process, starts to acquire multimodal real-time temperatures (external temperature of the steering wheel, internal temperature of the steering wheel, ambient temperature, etc.), and uses torque detection to obtain the steering wheel capacitance detection value, i.e., the target capacitance value, and determines whether the steering wheel is in a heating state. If so, time-division multiplexing is enabled; otherwise, it is used for detection all the time. Then, it is determined whether the target capacitance value is within the preset capacitance threshold of the corresponding scenario, and finally outputs whether the hands-off, hands-on, or hands-on states are detected. Then, it is determined whether the steering wheel has the ability to take over. If it does, the dynamic adaptive intelligent detection process ends.

[0295] If the conditions are not met, the advanced driver assistance system (ADAS) determines whether intelligent driving is activated. If not, the process ends. If activated, it determines whether the driver has taken their hands off the wheel and records the time. When the time is less than or equal to 15 seconds, a Level 1 alarm is activated, and a red pop-up window on the vehicle's infotainment system / instrument panel / HUD displays "Please keep your hands on the steering wheel and pay attention to the road conditions ahead." When the time is less than or equal to 30 seconds, a Level 2 alarm is activated, and a red pop-up window displays "Please keep your hands on the steering wheel and pay attention to the road conditions ahead" along with a voice "ding-dong" reminder. When the warning is followed by less than or equal to 30 seconds (at least 5 seconds for an escalation warning), a Level 3 alarm is activated, and a red pop-up window displays "Please take control of the vehicle" along with a voice announcement. When the time is greater than 43 seconds, a Level 4 alarm is activated, the screen turns red, and a red pop-up window displays "Please take control of the vehicle immediately" along with a voice announcement. Once the driver takes control of the vehicle, they exit the assisted driving mode, or the hazard lights are turned on, the vehicle is safely stopped after 5 seconds, and the driver takes control of the vehicle again, the assisted driving mode is exited, and the process ends.

[0296] The foregoing mainly describes the solutions provided by the embodiments of this application from a methodological perspective. To achieve the above functions, the steering wheel hands-off detection device includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0297] This application embodiment can, based on the above method, exemplarily divide the steering wheel hands-off detection device or electronic device into functional modules. For example, the steering wheel hands-off detection device or electronic device may include functional modules corresponding to each functional division, or two or more functions may be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division; in actual implementation, there may be other division methods.

[0298] like Figure 7 As shown, the electronic device 700 provided in this application embodiment includes, but is not limited to, a processor 701 and a memory 702.

[0299] The aforementioned memory 702 is used to store the executable instructions of the aforementioned processor 701. It is understood that the aforementioned processor 701 is configured to execute instructions to implement the vehicle battery power testing method described in the above embodiment.

[0300] It should be noted that those skilled in the art will understand that Figure 7 The electronic device structure shown does not constitute a limitation on electronic device 700; electronic device may include, but is not limited to, other electronic devices. Figure 7 This may indicate more or fewer components, or combinations of certain components, or different component arrangements.

[0301] The processor 701 is the control center of the electronic device 700. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 702, and by calling data stored in the memory 702, it performs various functions and processes data of the electronic device 700, thereby providing overall monitoring of the electronic device 700. The processor 701 may include one or more processing units. Optionally, the processor 701 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 701.

[0302] The memory 702 can be used to store software programs and various data. The memory 702 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs required by at least one functional module (such as a determination unit, processing unit, etc.), etc. Furthermore, the memory 702 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0303] In an exemplary embodiment, a computer-readable storage medium including instructions is also provided, such as a memory 702 including instructions, which can be executed by a processor 701 of an electronic device 700 to implement the methods in the above embodiments.

[0304] Optionally, the computer-readable storage medium may be a non-transitory computer-readable storage medium, such as a read-only memory (ROM), random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device.

[0305] In an exemplary embodiment, this application also provides a computer program product including one or more instructions, which can be executed by the processor 701 of the electronic device 700 to perform the methods described above.

[0306] It should be noted that when one or more instructions in the computer-readable storage medium or computer program product are executed by the processor of an electronic device, they implement the various processes of the above method embodiments and achieve the same technical effect as the above method. To avoid repetition, they will not be described again here.

[0307] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0308] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0309] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0310] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0311] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, essentially, or the parts that contribute to related technologies, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0312] The above embodiments are merely preferred embodiments provided to fully illustrate this application, and the scope of protection of this application is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on this application are all within the scope of protection of this application.

Claims

1. A method of off-hand detection of a steering wheel, characterized by, The method includes: Based on the operating state of the heating element of the steering wheel and / or the multimodal real-time temperature, the heating scenario corresponding to the steering wheel is determined; wherein, the multimodal real-time temperature includes the external temperature of the steering wheel, the internal temperature of the steering wheel, and the ambient temperature; the heating element is configured to be energized and generate heat in the heating mode, and to act as a capacitive sensing electrode in the detection mode; The preset capacitance threshold corresponding to the heating scenario is determined based on the threshold determination algorithm corresponding to the heating scenario. The original capacitance value sensed by the heating element is compensated based on the compensation coefficient to determine the target capacitance value; the compensation coefficient is determined based on the deviation between the multimodal real-time temperature and the corresponding calibration temperature. The target capacitance value is compared with the preset capacitance threshold corresponding to the heating scenario, and the contact state between the driver and the steering wheel is determined based on the comparison result.

2. The off-hand detection method of a steering wheel according to claim 1, characterized by, The compensation coefficient is determined based on the product of the first compensation coefficient and the deviation of the external temperature of the steering wheel from the calibrated temperature, the product of the second compensation coefficient and the deviation of the internal temperature of the steering wheel from the calibrated temperature, and the product of the third compensation coefficient and the deviation of the ambient temperature from the calibrated temperature. Wherein, the first compensator coefficient is greater than the second compensator coefficient, and the second compensator coefficient is greater than the third compensator coefficient.

3. The off-hand detection method of a steering wheel according to claim 1, characterized by, The compensation coefficient is determined based on the product of the first compensation coefficient and the deviation between the external temperature of the steering wheel and the corresponding calibration temperature, the product of the second compensation coefficient and the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature, the product of the third compensation coefficient and the deviation between the ambient temperature and the corresponding calibration temperature, and the product of the fourth compensation coefficient and the deviation between the ambient airflow speed and the corresponding calibration airflow speed. Wherein, the first compensator coefficient is greater than the second compensator coefficient, the second compensator coefficient is greater than the third compensator coefficient, and the third compensator coefficient is greater than the fourth compensator coefficient.

4. The off-hand detection method of a steering wheel according to claim 1, characterized by, The preset capacitance threshold includes a first capacitance threshold and a second capacitance threshold; wherein, the first capacitance threshold is greater than the second capacitance threshold. The step of comparing the target capacitance value with a preset capacitance threshold corresponding to the heating scenario, and determining the contact state between the driver and the steering wheel based on the comparison result, includes: If the target capacitance value is greater than or equal to the first capacitance threshold, the contact state is determined to be a grip state. If the target capacitance value is less than the first capacitance threshold and greater than or equal to the second capacitance threshold, the contact state is determined to be a pallet-touching state. If the duration for which the target capacitance value is less than the second capacitance threshold reaches a preset release duration, the contact state is determined to be a release state.

5. The off-hand detection method of a steering wheel according to claim 1, characterized by, Determining the heating scenario corresponding to the steering wheel includes: When the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is greater than the first temperature difference threshold, the heating scenario is determined to be an air conditioning direct blowing scenario. The threshold determination algorithm for the direct airflow scenario is used to determine the preset capacitance threshold for the direct airflow scenario based on the product of a basic threshold and a first temperature compensation factor. The first temperature compensation factor is determined based on the deviation between the external temperature of the steering wheel, the ambient temperature, and their respective calibration temperatures.

6. The off-hand detection method of a steering wheel according to claim 1, characterized by, Determining the heating scenario corresponding to the steering wheel includes: When the heating element is not in heating mode, the vehicle's total power-on time is less than or equal to a preset power-on time threshold, and the rate of change of the steering wheel's internal temperature is greater than a second rate of change threshold, the heating scenario is determined to be a cold start power-on scenario. The threshold determination algorithm for the cold start power-on scenario is used to determine the preset capacitor threshold for the cold start power-on scenario based on the product of the basic threshold and the second temperature compensation factor. The second temperature compensation factor is determined based on the deviation between the internal temperature of the steering wheel and the initial internal temperature of the steering wheel when the vehicle is powered on.

7. The off-hand detection method of a steering wheel according to claim 1, characterized by, Determining the heating scenario corresponding to the steering wheel includes: When the heating element is not in heating mode and the absolute value of the difference between the external temperature of the steering wheel and the ambient temperature is less than or equal to the first temperature difference threshold, the heating scenario is determined to be a normal unheated scenario. The threshold determination algorithm for the conventional unheated scenario is used to determine the preset capacitance threshold for the conventional unheated scenario based on the inherent parasitic capacitance of the heating element and the preset effective grip capacitance of the steering wheel.

8. The off-hand detection method of a steering wheel according to claim 1, characterized by, Determining the heating scenario corresponding to the steering wheel includes: When the heating element is in heating mode and the rate of change of the external temperature of the steering wheel is greater than a first rate of change threshold, the heating scenario is determined to be a heating scenario; or, When the heating element is in heating mode and the duration of the change rate of the external temperature of the steering wheel being less than or equal to the second change rate threshold reaches a preset stable duration, the heating scenario is determined to be a heating stable scenario. The threshold determination algorithm corresponding to the heating period scenario or the heating stability scenario is used to determine the preset capacitance threshold corresponding to the heating period scenario or the heating stability scenario based on the product of the basic threshold and the third temperature compensation factor; the third temperature compensation factor is determined based on the external temperature of the steering wheel and the initial internal temperature of the steering wheel when the heating element is turned on, as well as the deviation between the internal temperature of the steering wheel and the corresponding calibration temperature.

9. The off-hand detection method of a steering wheel according to claim 1, characterized by, Determining the heating scenario corresponding to the steering wheel includes: When the heating element's working state ends after the heating mode ends, and the rate of change of the external temperature of the steering wheel is less than or equal to the first rate of change threshold and continues to reach a preset stable duration, the heating scenario is determined to be a heating off transition scenario. The threshold determination algorithm for the closed heating transition scenario is used to determine the preset capacitance threshold for the closed heating transition scenario based on the preset capacitance threshold for the heating scenario before entering the closed heating transition scenario and the preset capacitance threshold for the normal unheated scenario.

10. The off-hand detection method of a steering wheel according to claim 9, characterized by, The process of determining the preset capacitance threshold corresponding to the heating shutdown transition scenario includes: During multiple consecutive control cycles of the heating shutdown transition scenario, each control cycle corresponds to a preset capacitance threshold. The preset capacitance threshold corresponding to the heating scenario just before entering the heating off transition scenario is determined as the preset capacitance threshold of the first control cycle; the first control cycle is the first control cycle among the plurality of consecutive control cycles; The preset capacitance threshold under the normal unheated scenario is determined as the preset capacitance threshold of the second control cycle; the second control cycle is the last control cycle among the plurality of consecutive control cycles; According to the preset gradual change rule, based on the preset capacitance threshold of the first control cycle, the preset capacitance threshold of the second control cycle is approached cycle by cycle to determine the preset capacitance threshold of the heating shutdown transition scenario.

11. The off-hand detection method of a steering wheel according to claim 1, characterized by, The method further includes: In the heating scenario, the heating duration, the switching protection duration, and the capacitor detection duration are executed sequentially within each preset control cycle; each preset control cycle is any one of multiple consecutive control cycles in the heating scenario. The heating duration is one preset control cycle minus the sum of the switching protection duration and the capacitor detection duration; the heating duration is determined based on the difference between the external temperature of the steering wheel and the preset target temperature; the preset target temperature is determined based on the driver's needs.

12. A vehicle characterized by comprising: The vehicle includes a processor for performing the method as described in any one of claims 1-11.

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