Caliper low drag control method, system and vehicle based on a brake-by-wire EMB system

Abstract

The application provides a caliper low drag control method, system and vehicle based on a line control brake EMB system, and relates to the technical field of automobile brake control. The method calculates a dynamic target gap and controls a disc gap by acquiring a brake disc temperature signal and a caliper wear state signal, calculates a comprehensive intention score according to a pedal opening, a vehicle speed and a road adhesion coefficient, and outputs a drag torque control instruction according to a four-stage state machine switching rule with a hysteresis mechanism. The application realizes adaptive dynamic adjustment of the disc gap, and meets the dual requirements of low drag and fast response.

Description

Technical Field

[0001] This invention relates to the field of automotive braking control technology, and in particular to a caliper low-drag control method, system, and vehicle based on a brake-by-wire (EMB) system. Background Technology

[0002] In traditional hydraulic braking systems, the piston of the hydraulic brake caliper returns to its original position after the brake is released, which is achieved by the elastic deformation of the rectangular sealing ring. This return process is time-consuming and the amount of return is unstable. At the same time, the residual pressure in the master cylinder also hinders the piston from returning to its original position completely, resulting in a dragging torque in the caliper after the brake is released, which increases driving resistance and affects the overall vehicle energy consumption.

[0003] With the development of brake-by-wire (EMB) technology, existing solutions have proposed EMB-based caliper clearance adjustment methods. These methods calculate the real-time friction coefficient under different operating conditions and combine it with a segmented control strategy to achieve clearance adjustment. However, in practical applications, both the brake disc and friction pads expand at high temperatures, and the friction pads wear down over long-term use. These factors cause changes in the actual disc-pad clearance. Existing solutions using fixed target clearance values ​​cannot effectively address these changes, resulting in unstable disc-pad clearance after brake release. Summary of the Invention

[0004] To address the technical problems mentioned above, this invention provides a caliper low-drag control method, system, and vehicle based on a brake-by-wire (EMB) system.

[0005] To achieve the above objectives, the first aspect of the present invention provides a caliper low-drag control method based on a brake-by-wire (EMB) system, comprising: Acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal; The dynamic target clearance is calculated based on the brake disc temperature signal and the caliper wear status signal, and the caliper disc clearance is controlled based on the dynamic target clearance. Calculate the overall intent score based on the pedal opening signal, the vehicle speed signal, and the road surface adhesion coefficient signal; Based on the comprehensive intent score and the current caliper operating state, the target caliper operating state is determined according to the four-level state machine switching rules with hysteresis mechanism, and the drag torque control command corresponding to the target caliper operating state is output.

[0006] Furthermore, the dynamic target clearance is obtained by adding the reference clearance, temperature compensation, and wear compensation. The temperature compensation is calculated based on the thermal expansion of the brake disc, and the wear compensation is calculated based on the accumulated wear displacement of the caliper friction pair during use. The calculation formula for the dynamic target clearance is:

[0007] in, For dynamic target gaps, As the reference gap, This is the temperature compensation amount. This is the amount of wear compensation.

[0008] Furthermore, the thermal expansion is calculated based on the current brake disc temperature, temperature-dependent thermal expansion coefficient, material density correction factor, brake disc thickness, and reference temperature, and then multiplied by the gap. After the expansion conversion coefficient is applied, the thermal expansion is then limited to a preset upper and lower limit range by a saturation limiting function to obtain the temperature compensation amount; the calculation formula for the thermal expansion amount is:

[0009] in, This represents the amount of thermal expansion of the brake disc in the direction perpendicular to the friction working surface. The coefficient of thermal expansion is the temperature-dependent coefficient. This is the material density correction factor. For brake disc thickness, This is the current brake disc temperature. The reference temperature is used; the formula for calculating the temperature compensation is:

[0010] in, This is the gap-to-expansion conversion coefficient. It is a saturation limiting function. and These are the lower and upper limits of the temperature compensation, respectively.

[0011] Furthermore, the wear compensation amount is obtained as follows: using a recursive least squares method with a forgetting factor, the current wear contact point angle is recursively estimated based on the actual contact point angle detected during each braking. The difference between the currently estimated wear contact point angle and the initial contact point angle is used as the cumulative wear angle increment. Then, based on the lead screw lead, the cumulative wear angle increment is converted into a displacement compensation amount to obtain the wear compensation amount.

[0012] in, For the first Estimated wear contact points per braking cycle Forgetting factor, For the first The actual contact point angle detected during the second braking; the conversion formula for displacement compensation is:

[0013] in, To accumulate the wear angle increment, This refers to the lead of the leadscrew.

[0014] Furthermore, the process of calculating the comprehensive intent score includes: dynamically adjusting the acceleration confirmation threshold used to determine acceleration intent based on the vehicle speed signal, the road surface adhesion coefficient signal, and the acquired longitudinal acceleration signal; determining the emergency stop threshold based on the vehicle speed signal and the road surface adhesion coefficient signal, and acquiring the pedal opening change rate signal and the pedal acceleration signal; when the pedal opening change rate is less than the emergency stop threshold and the absolute value of the pedal acceleration is greater than a preset jitter threshold, it is determined to be a valid emergency stop state; normalizing and weighting the acquired forward collision time signal, road slope signal, navigation prediction signal, and pedal opening signal, and combining them with the determination result of the valid emergency stop state, to obtain a comprehensive intent score with a value range of 0 to 1.

[0015] Furthermore, the acceleration confirmation threshold is adjusted as follows: the baseline acceleration confirmation threshold is multiplied sequentially by the vehicle speed correction factor, the road surface adhesion correction factor, and the longitudinal acceleration correction factor to obtain the final acceleration confirmation threshold; wherein, the vehicle speed correction factor adopts the form of a sigmoid function, which approaches 1 at low speeds and approaches 0 at high speeds; the road surface adhesion correction factor decreases in value on low-adhesion roads to lower the threshold; and the longitudinal acceleration correction factor increases in value when the vehicle accelerates to raise the threshold.

[0016] Furthermore, the four-level state machine includes an idle standby state, a pre-pressure holding state, a rapid approach state, and a braking pressure building state. The disc clearance corresponding to each state decreases sequentially, with the largest clearance in the idle standby state, a preset smaller clearance in the pre-pressure holding state, and a clearance close to zero in the rapid approach state. The braking pressure building state is used to apply braking torque. The hysteresis mechanism is as follows: each state has an upshift threshold and a downshift threshold, and the upshift threshold of the same state is greater than the downshift threshold, with the difference between the two forming a dead zone. When switching states, if the current comprehensive intention score is greater than the upshift threshold of the current state, the state switches to a higher hysteresis state; if the current comprehensive intention score is less than the downshift threshold of the current state, the state switches to a lower hysteresis state; if the current comprehensive intention score is between the upshift threshold and the downshift threshold of the current state, the current state remains unchanged.

[0017] Furthermore, the brake disc temperature signal is acquired in real time by the temperature sensor built into the EMB caliper controller, and the sensor measurement value is indirectly converted into the actual brake disc temperature through a pre-calibrated temperature model; the caliper wear status signal is obtained by detecting the motor rotation angle corresponding to the contact point during braking through the motor position sensor, and based on the change in the contact point angle during multiple braking cycles.

[0018] Furthermore, the method also includes: acquiring forward collision time signal, road slope signal, navigation prediction signal, and longitudinal acceleration signal; The comprehensive intent score is calculated as follows: a basic intent value is determined based on the pedal opening signal; the basic intent value is corrected based on the forward collision time signal, wherein the forward collision time is negatively correlated with the corrected intent value, and the basic intent value increases by a preset proportion when the forward collision time is less than a preset collision risk threshold; the basic intent value is corrected based on the road slope signal, wherein the road slope is positively correlated with the corrected intent value, and the basic intent value increases by a preset proportion when the absolute value of the downhill slope exceeds a preset slope threshold; the basic intent value is corrected based on the navigation prediction signal, and the basic intent value increases by a preset amplitude when the navigation predicts a curve or traffic light ahead; and the basic intent value is corrected based on the longitudinal acceleration signal, wherein the longitudinal acceleration is positively correlated with the corrected intent value. The modified intent value is then normalized and weighted in conjunction with the results of the accelerated confirmation threshold and the emergency collection threshold to obtain the comprehensive intent score.

[0019] A second aspect of the present invention provides a caliper low-drag control system based on a brake-by-wire (EMB) system, comprising: The signal acquisition module is used to acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal; The dynamic clearance correction module is used to calculate the dynamic target clearance based on the brake disc temperature signal and the caliper wear state signal, and to control the disc clearance of the caliper based on the dynamic target clearance. The intent fusion module is used to calculate a comprehensive intent score based on the pedal opening signal, the vehicle speed signal, and the road surface adhesion coefficient signal. The state machine control module is used to determine the target caliper's working state according to the comprehensive intent score and the current caliper working state, following the four-level state machine switching rules with hysteresis mechanism, and output the drag torque control command corresponding to the target caliper's working state.

[0020] Furthermore, the dynamic gap correction module includes a temperature compensation submodule, which has a brake disc temperature signal input terminal, a temperature compensation coefficient memory, and a temperature compensation amount output terminal. The temperature compensation coefficient memory stores temperature... Thermal expansion coefficient mapping table, material density correction factor and gap Expansion conversion coefficient; The wear compensation submodule has a contact point angle signal input terminal, a lead screw lead parameter memory, and a wear compensation output terminal. The contact point angle signal input terminal is connected to the input interface of the motor position sensor. The wear compensation submodule is equipped with a recursive least squares estimator with a forgetting factor. The adder has its first input terminal connected to the temperature compensation output terminal, its second input terminal connected to the wear compensation output terminal, and its third input terminal connected to the reference gap parameter memory. Its output terminal outputs the dynamic target gap control signal.

[0021] Furthermore, the intent fusion module includes: The acceleration confirmation threshold calculation submodule has a vehicle speed signal input terminal, a road surface adhesion coefficient signal input terminal and a longitudinal acceleration signal input terminal. It internally stores the benchmark acceleration confirmation threshold and the sigmoid function parameter table. Its output terminal outputs the acceleration confirmation threshold after correction by vehicle speed, adhesion coefficient and longitudinal acceleration. The emergency retraction determination submodule has a pedal opening change rate signal input terminal, a pedal acceleration signal input terminal, a vehicle speed signal input terminal, and a road surface adhesion coefficient signal input terminal. It internally stores the reference emergency retraction threshold and jitter threshold parameters, and its output terminal outputs a valid emergency retraction indicator signal. The scoring fusion submodule has its signal input terminals connected to the output terminals of the accelerated confirmation threshold calculation submodule and the rapid settlement determination submodule, respectively. It has a multi-channel signal weighting fusion circuit inside, and its output terminal outputs the comprehensive intent score signal.

[0022] Furthermore, the state machine control module includes: The state memory is used to store the current caliper operating state identifier, which is selected from one of the following: idle standby state, pre-pressure holding state, rapid approach state, and brake pressure building state. A threshold comparator has its first input connected to the output of the intent recognition unit to receive the comprehensive intent score signal, its second input connected to the up-threshold register, and its third input connected to the down-threshold register. The threshold comparator outputs a comparison result signal. A state switching controller has its input connected to the output of the threshold comparator and its output connected to the update control terminal of the state memory. The state switching controller controls the update of the working state identifier in the state memory according to the comparison result signal. It internally stores a switching logic rule table between each state. The instruction output interface has its input end connected to the output end of the state memory, and its output end outputs the drag torque control instruction corresponding to the current working state.

[0023] A third aspect of the present invention provides a vehicle including a caliper low-drag control system based on a brake-by-wire (EMB) system provided in the second aspect of the present invention.

[0024] Compared with existing technologies, the present invention provides a caliper low-drag control method, system, and vehicle based on a brake-by-wire (EMB) system. By incorporating the thermal expansion of the brake disc caused by temperature changes and the wear of the friction pair due to long-term use into the real-time calculation of the target clearance, the caliper disc clearance can be dynamically adjusted according to operating conditions rather than remaining fixed. This allows for automatic increase of the clearance under high-temperature conditions to avoid drag loss, and automatic adjustment of the clearance after wear accumulation to maintain braking responsiveness. This achieves adaptive adjustment of the disc clearance, balancing the dual requirements of low drag and fast response. Attached Figure Description

[0025] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0026] Figure 1 The flowchart shows a caliper low drag control method based on a brake-by-wire (EMB) system provided in Embodiment 1 of the present invention.

[0027] Figure 2 This is an architecture diagram of a caliper low-drag control system based on a brake-by-wire (EMB) system provided in Embodiment 2 of the present invention.

[0028] Figure 3 This is a schematic diagram illustrating the hydraulic brake caliper piston return principle provided in Embodiment 2 of the present invention. Figure 3 A in the diagram represents the braking state. Figure 3 B in the diagram represents the brake release state.

[0029] In the diagram, 301 is the caliper housing; 302 is the piston; 303 is the rectangular sealing ring; and 304 is the dust cover. Detailed Implementation

[0030] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the invention. In the description of the embodiments of the present invention, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "this embodiment" should be understood as "at least one embodiment". The terms "first" and "second" 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 as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this embodiment, unless otherwise stated, "a plurality of" means two or more.

[0031] Before describing specific embodiments of the present invention, the key terms involved in the present invention will first be explained: 1. Electro-Mechanical Brake (EMB) system: A brake-by-wire system that eliminates brake fluid and hydraulic lines, and achieves braking by driving the brake caliper with a motor. The brake pedal and brake actuator are completely decoupled, and the piston return amount can be precisely controlled by a motor position sensor.

[0032] 2. Disc clearance: The clearance between the brake friction pads and the brake disc is a key parameter that affects drag torque and braking response time.

[0033] 3. Dragging torque: After the brake is released, the residual friction torque generated because the friction pads have not completely detached from the brake disc will increase driving resistance and affect the overall vehicle energy consumption.

[0034] 4. Comprehensive Intent Score: A quantitative indicator reflecting the urgency of the driver's current braking needs, calculated by integrating multi-dimensional information such as driver pedal operation, traffic conditions ahead, road environment, and vehicle status.

[0035] 5. Contact point angle: During braking, the motor drives the lead screw to push the piston to move. When the friction plate just contacts the brake disc, the rotation angle of the motor rotor can be obtained by detecting the motor position sensor.

[0036] Example 1 like Figure 1 This embodiment provides a caliper low-drag control method based on a brake-by-wire (EMB) system, including: S101: Acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal.

[0037] The brake disc temperature signal is acquired in real time by a temperature sensor built into the EMB caliper controller and indirectly converted to the actual brake disc temperature using a temperature model pre-calibrated on a test bench. Since the brake disc rotates at high speed during operation, a temperature sensor cannot be directly mounted on the brake disc to measure its temperature. Therefore, an indirect measurement scheme is adopted: a temperature sensor built into the EMB caliper controller measures the caliper body temperature, and then the actual brake disc temperature is converted using a temperature mapping relationship calibrated on the test bench (i.e., the corresponding curve between the sensor measurement value and the actual brake disc temperature). The caliper wear status signal is obtained by detecting the motor rotation angle corresponding to the contact point during braking using a motor position sensor, and based on the change in the contact point angle over multiple braking cycles. The motor angle at the instant of contact between the friction pad and the brake disc is recorded during each braking action. The change in this angle over multiple braking cycles reflects the wear of the friction pad. This method fully utilizes the existing motor position sensor resources of the EMB system, achieving online monitoring of wear status without additional hardware costs. The pedal opening signal is acquired by a pedal position sensor to reflect the driver's braking intensity. The vehicle speed signal is provided by wheel speed sensors or the vehicle controller. The road surface adhesion coefficient signal is obtained by the road surface adhesion coefficient estimation module in real time based on signals such as wheel speed and longitudinal acceleration.

[0038] S102. Calculate the dynamic target clearance based on the brake disc temperature signal and the caliper wear status signal, and control the caliper disc clearance based on the dynamic target clearance.

[0039] Specifically, the dynamic target clearance is obtained by adding the reference clearance, temperature compensation, and wear compensation, and its calculation formula is as follows:

[0040] in, The dynamic target gap (unit: mm). This is the reference clearance (calibrated value, such as 0.3mm, representing the ideal clearance under normal temperature and no wear conditions). Temperature compensation amount (unit: mm). The wear compensation amount is in mm. By decomposing the dynamic target clearance into three independent components, temperature compensation and wear compensation can be designed and calibrated separately, reducing system complexity and improving control accuracy.

[0041] Temperature compensation The method for obtaining this information is as follows: First, calculate the thermal expansion of the brake disc in the direction perpendicular to the friction working surface based on the current brake disc temperature. The calculation formula is as follows:

[0042] in, This represents the amount of thermal expansion of the brake disc in the direction perpendicular to the friction working surface. The coefficient of thermal expansion is the temperature-dependent coefficient (unit: 1 / ℃, typical value for cast iron is 1.0 × 10⁻⁶). -5 / ℃, this coefficient changes non-linearly with temperature and is obtained by looking up a table or by polynomial fitting). This is a material density correction factor (used to account for the effect of casting porosity on thermal expansion behavior, typically 0.95~1.0). Brake disc thickness (unit: mm, e.g., 28 mm). The current brake disc temperature (unit: °C, obtained by real-time acquisition from temperature sensor and converted by temperature model). The reference temperature is (unit: °C, calibration value, e.g., 20 °C). Then, the thermal expansion is multiplied by the gap-expansion conversion factor, and then limited within a preset upper and lower limit range using a saturation limiting function to obtain the temperature compensation amount. The calculation formula is:

[0043] in, This is the gap-expansion conversion factor (calibrated according to caliper geometry, typical value 0.5~0.8). It is a saturation limiting function. and These are the lower and upper limits for temperature compensation (unit: mm, e.g., -0.1mm and +0.2mm), used to prevent excessive compensation under extreme temperature conditions from causing slow braking response or insufficient clearance. Furthermore, the friction pads themselves expand when heated. Based on actual measurements of the friction pad thickness change at different temperatures, a temperature-thickness change model curve is pre-established. During actual control, the friction pad expansion value at the current temperature is obtained through interpolation and superimposed on the dynamic clearance correction model. This temperature compensation method solves the problem of accurately calculating the impact of thermal expansion on the disc-pad clearance from indirectly measured brake disc temperature signals, achieving precise quantitative calculation of the brake disc thermal expansion and friction pad thermal expansion.

[0044] Wear compensation amount The method for obtaining this angle is as follows: A recursive least squares method with a forgetting factor is used to recursively estimate the current wear contact point angle based on the actual contact point angle detected during each braking action. During each braking action, at the instant the friction pads just make contact with the brake disc, the motor current will change abruptly, or the force sensor will output a signal; the motor rotation angle corresponding to this moment is the actual contact point angle. Its recursive estimation formula is:

[0045] in, For the first Estimated wear contact points per braking cycle Forgetting factor, For the first The actual contact point angle detected during the second braking.

[0046] Forgetting factor The introduction of this allows the algorithm to balance the weights of historical data and current data. The larger the value, the higher the weight of historical data, the smoother the estimated value, and the stronger the noise resistance. The smaller the value, the higher the weight of the current data, and the faster the estimate tracks wear changes. The difference between the currently estimated wear contact point angle and the initial contact point angle is used as the cumulative wear angle increment. Then, based on the lead screw pitch, the cumulative wear angle increment is converted into displacement compensation. The conversion formula is as follows:

[0047] in, The cumulative wear angle increment (unit: degrees, equal to the difference between the current estimated contact point angle and the initial contact point angle). The lead of the lead screw is in mm (e.g., 5 mm / revolution). The above wear compensation method solves the problem of extracting the wear amount of the friction plates from the angle signal of the motor position sensor and converting it into a clearance compensation value. This enables online real-time estimation of wear, automatically compensating for the impact of wear on the clearance without requiring the machine to stop for inspection.

[0048] Using the aforementioned dynamic target clearance as the control objective, the EMB controller controls the motor rotation angle through a closed-loop control system via a motor position sensor, ensuring the piston moves accurately to the position corresponding to the target clearance. Compared to existing technologies that use a fixed target clearance value, this step incorporates the thermal expansion of the brake disc and friction pads caused by temperature changes, as well as the wear generated by long-term use of the friction pair, into the real-time calculation of the target clearance. This allows the caliper disc clearance to be dynamically adjusted according to operating conditions rather than remaining fixed. Under high-temperature conditions, the clearance is automatically increased to avoid drag and wear, and the clearance is automatically adjusted after wear accumulation to maintain braking responsiveness, thus meeting the dual requirements of low drag and fast response.

[0049] S103. Calculate the comprehensive intent score based on the pedal opening signal, the vehicle speed signal, and the road surface adhesion coefficient signal.

[0050] The overall intent score quantifies the urgency of the driver's current braking need and is the core basis for subsequent state machine transitions. The process of calculating the overall intent score includes the following aspects: (1) Acceleration confirmation threshold adaptive adjustment: Based on the vehicle speed signal, road surface adhesion coefficient signal and the acquired longitudinal acceleration signal, the acceleration confirmation threshold used to determine acceleration intention is dynamically adjusted. The calculation formula is:

[0051] in, To accelerate the confirmation of the threshold (calibrated value, e.g., 30%), The speed correction factor is expressed using the sigmoid function. ,in, This is the curve steepness coefficient. For reference vehicle speed (e.g., 60 km / h), this correction factor approaches 1 at low speeds and approaches 0 at high speeds. This means that the threshold is lowered and the system is more responsive at high speeds because the requirements for braking response are higher at high speeds. The road surface adhesion correction factor is calculated using the following formula: ,in, This is a correction factor for the adhesion coefficient, for low-adhesion road surfaces ( When the threshold is lower (to a smaller value), the system enters a high drag state earlier on wet and slippery surfaces to ensure safety. The longitudinal acceleration correction factor is given by the formula: ,in, The acceleration correction coefficient increases the threshold during vehicle acceleration to reduce false triggering. All three are dimensionless correction factors with values ​​ranging from (0, 1.5], determined based on actual vehicle calibration. This adaptive adjustment method solves the problem of poor adaptability of the fixed acceleration confirmation threshold under different vehicle speeds, road surfaces, and driving conditions, achieving condition-adaptive adjustment of the acceleration confirmation threshold and reducing false triggering while ensuring safety.

[0052] (2) Multivariate mapping of emergency retraction threshold and determination of effective emergency retraction state: The emergency retraction threshold is determined based on vehicle speed signal and road surface adhesion coefficient signal. The calculation formula is:

[0053] in, The baseline rapid contraction threshold (calibrated value, e.g., -50% / s) The function is a piecewise function for vehicle speed (1.0 for low speed and 0.6 for high speed to improve sensitivity). for Adhesion coefficient correction function (reduces the absolute value of the threshold on wet and slippery surfaces to enable the system to respond earlier). The effective quick-release condition is determined by the rate of change of pedal opening. Less than And pedal acceleration The absolute value is greater than the jitter threshold. (e.g., 200% / s²).

[0054] (3) Calculation of comprehensive intent score: The acquired forward collision time signal (TTC), road slope signal, navigation prediction signal and pedal opening signal are normalized and weighted and fused, and combined with the determination result of the effective emergency stop state, to obtain a comprehensive intent score with a value range of 0 to 1. .

[0055] Specifically, the basic intent value is determined based on the pedal opening signal (the larger the pedal opening, the higher the basic intent value); the basic intent value is corrected based on the forward collision time signal, where the forward collision time is negatively correlated with the corrected intent value. When the forward collision time is less than a preset collision risk threshold, the basic intent value increases by a preset proportion (i.e., the higher the collision risk, the higher the intent value); the basic intent value is corrected based on the road slope signal, where the road slope is positively correlated with the corrected intent value. When the absolute value of the downhill slope exceeds a preset slope threshold, the basic intent value increases by a preset proportion (the steeper the downhill slope, the more the vehicle tends to accelerate, and the greater the braking demand); the basic intent value is corrected based on the navigation prediction signal. When the navigation predicts a curve or traffic light ahead, the basic intent value increases by a preset amplitude (indicating that deceleration is imminent); the basic intent value is corrected based on the longitudinal acceleration signal, where the longitudinal acceleration is positively correlated with the corrected intent value (increased longitudinal acceleration indicates that the vehicle is accelerating or at a higher speed, and the braking demand is correspondingly increased). The modified intention value is then normalized and weighted in conjunction with the acceleration confirmation threshold and emergency braking threshold determination results to obtain a comprehensive intention score. This multi-dimensional fusion method solves the problem that existing technologies rely solely on a single pedal opening signal to determine braking intention, making it difficult to adjust caliper status in advance under complex conditions such as emergency obstacle avoidance and downhill driving. It achieves the organic integration of environmental prediction information and driver operation information, enabling the system to predict braking needs in advance under complex conditions.

[0056] S104. Based on the comprehensive intent score and the current caliper working state, determine the target caliper working state according to the four-level state machine switching rules with hysteresis mechanism, and output the drag torque control command corresponding to the target caliper working state.

[0057] The four-level state machine divides the caliper's working state into four levels, with the disc clearance decreasing sequentially for each state: S0 idle standby state (maximum clearance, approximately 0.5mm, minimum lag, suitable for cruising conditions with no braking demand), S1 pre-pressure holding state (clearance approximately 0.2mm, piston slightly engaged, quick response, suitable for conditions with slight braking anticipation), S2 rapid approach state (clearance approaching zero, preparing to build pressure, suitable for emergency braking or conditions with clear braking demand), and S3 brake pressure building state (applying braking torque, suitable for full braking conditions). The core of the state switching lies in the hysteresis mechanism: each state has a separate upshift threshold. and downshift threshold ,satisfy dead zones (Typical value 0.1~0.2). The state transition logic is as follows: The current status is At that time, the next state The judgment rule is: like ,but (Upshift, entering a higher lag state); like ， but (Downshift, returning to low lag state); like ,but (Maintain the current state and do not switch within the dead zone).

[0058] During state transitions, if the current overall intent score is greater than the upshift threshold of the current state, the system shifts to a higher hysteresis state (upshift); if the current overall intent score is less than the downshift threshold of the current state, the system shifts to a lower hysteresis state (downshift); if the current overall intent score is between the upshift and downshift thresholds of the current state (i.e., within the dead zone), the current state remains unchanged. This hysteresis mechanism prevents frequent switching between adjacent states when the driver's pedal operation is near the threshold or when road bumps cause signal jitter. Switching is only performed when the intent score clearly exceeds the upshift or downshift threshold, effectively shielding signal fluctuations within the dead zone. This solves the problem of frequent oscillations near the threshold in traditional single-threshold state machines, reduces wear caused by frequent forward and reverse switching of the motor, extends motor lifespan, and avoids braking shocks caused by state jumps, improving driving comfort. Finally, based on the target caliper's operating state, the corresponding drag torque control command is output to the EMB caliper's motor drive module, controlling the motor to perform corresponding clearance adjustment or pressure build-up actions.

[0059] The control method of the present invention will be described in detail below through three specific operating conditions.

[0060] Specific Implementation Example 1: Low-Speed ​​Following Scenario in Urban Driving Conditions The vehicle was traveling at 30 km / h in urban areas, following other vehicles, with the brake disc temperature at 80℃ and a cumulative mileage of 5000 km.

[0061] Step 1: Dynamic gap correction (1) Temperature compensation: According to the formula ,Pick (Obtained by looking up the temperature-thermal expansion coefficient mapping table). , , Calculated .

[0062] According to the formula ,Pick , , Calculated .

[0063] Here, the expansion value of the friction plate at 80℃ should also be obtained by interpolation based on the friction plate temperature-thickness change model curve, and superimposed on the temperature compensation (in this embodiment, the friction plate expansion is 0.002mm, and the total temperature compensation after superposition is 0.0124mm). (2) Wear compensation: Historical data shows the initial contact point angle Current estimated contact point (Using a recursive least squares formula with a forgetting factor), cumulative wear angle increment According to the formula ,Pick Calculated .

[0064] (3) Dynamic target gap: According to the formula ,Pick Calculated The system adjusts the caliper clearance to 0.421 mm, which, compared to a fixed 0.3 mm strategy, compensates for the effects of temperature expansion and wear accumulation.

[0065] Step 2: Multidimensional Intent Fusion The vehicle ahead has a TTC of 5 seconds (sufficient safe distance), the road gradient is 0° (flat road), the navigation did not predict any abnormality ahead, and the driver's pedal opening is 10% (light braking). Calculate the overall intent score. (Low braking intention)

[0066] Step 3: State Machine Switching The current state is S0 idle standby, upgrade threshold. The downgrade threshold does not apply. Because... The system remains in state S0, with the gap maintained at 0.421 mm, achieving low drag operation.

[0067] In urban low-speed following conditions, the clearance was adjusted from a fixed value of 0.3mm to 0.421mm through dynamic clearance correction, which effectively compensated for the impact of temperature expansion and wear accumulation on the clearance, ensuring low drag operation while maintaining appropriate braking response capability.

[0068] Specific Implementation Example 2: Emergency Braking Scenario on Highway The vehicle traveled at 100 km / h on the highway, with the brake disc temperature at 150℃, and accumulated a mileage of 20,000 km.

[0069] Step 1: Dynamic gap correction (1) Temperature compensation: Take (Obtained by looking up the temperature-thermal expansion coefficient mapping table). , , Calculated .

[0070] Pick Calculated .

[0071] (2) Wear compensation: Current estimated contact point Cumulative wear angle increment Calculated .

[0072] (3) Dynamic target gap: calculated High temperature and long-term wear increased the target clearance to 0.671 mm, effectively avoiding dragging losses caused by thermal expansion.

[0073] Step 2: Multidimensional Intent Fusion An obstacle suddenly appears ahead, and the TTC drops sharply to 1.5 seconds (dangerous). The driver abruptly pulls back on the pedals, and the pedal opening change rate... Pedal acceleration (Absolute value greater than jitter threshold 200% / s²).

[0074] According to the formula ,Pick , (High-speed increase in sensitivity) (Dry road surface), calculated .because and This is determined to be a valid emergency withdrawal. Overall Intent Score (High braking intention)

[0075] Step 3: State Machine Switching The current state is S0 idle standby, because Far exceeding the upgrade threshold The system sequentially and rapidly switches to S1 pre-pressure holding → S2 rapid approach → S3 braking pressure build-up. The caliper completes gap elimination and establishes braking torque within 150 ms, which shortens the response time by 20% compared to the fixed gap strategy and effectively avoids collisions.

[0076] Step 4: Validation of the hysteresis mechanism After braking is complete, the driver slowly releases the pedal. It gradually decreases from 0.95. When When it drops to 0.65 (still higher than the downshift threshold from S2 to S1), The system remains in S2 state without switching until... The system only transitioned from S2 to S1 when the value dropped to 0.48. Hysteresis dead zone. It effectively suppresses state oscillations caused by minor pedal vibrations, reducing the number of switching operations by 55% compared to the hysteresis-free solution.

[0077] The verification of the above hysteresis mechanism shows that by setting an upshift threshold greater than the downshift threshold in each state to form a dead zone, the frequent state switching caused by signal noise is effectively shielded, the number of forward and reverse switching of the motor is reduced, the service life of the motor is extended, and the braking shock caused by state jumps is avoided.

[0078] Specific Implementation Example 3: Downhill Scenario on a Wet and Slippery Road The vehicle is traveling downhill at 50 km / h on a wet, slippery road surface (-5% gradient). The road adhesion coefficient... The brake disc temperature is 60℃.

[0079] Step 1: Dynamic gap correction Calculated , , .

[0080] Step 2: Multidimensional Intent Fusion The navigation system predicts a curve 1 km ahead, and the gradient sensor detects a -5% downhill slope. This is based on the baseline value of the overall intent score. According to the formula ,Pick , , (Low adhesion reduces the threshold) (Without acceleration), the calculation yields... Because the driver's pedal opening was 12% (exceeding the adaptive threshold of 17.9%), and the downhill and curve prediction signals were enhanced, ultimately... Revised to 0.55.

[0081] Step 3: State Machine Switching The current state is S0 idle standby, because The system switches to S1 preload holding mode, reducing the caliper gap to 0.2 mm in advance to prepare for subsequent braking. Compared to strategies without multidimensional intent fusion, the system enters the preload state 180 ms earlier, significantly improving braking safety on wet and slippery downhill surfaces.

[0082] In the scenario of going downhill on a wet and slippery road, the multi-dimensional intent fusion module recognizes the downhill slope and curve prediction signals, enabling the system to predict the braking demand and adjust the caliper status in advance before the driver presses the pedal deeply, effectively making up for the delay in braking response on wet and slippery roads.

[0083] The above embodiments verify the effectiveness of the present invention under different working conditions: the dynamic gap correction model realizes temperature / wear adaptive compensation, the multi-dimensional intent fusion module improves the intent recognition accuracy under complex working conditions, and the hysteresis state machine effectively suppresses frequent oscillations. The overall performance is significantly better than the prior art.

[0084] Example 2 This embodiment provides a caliper low drag control system based on a brake-by-wire (EMB) system.

[0085] Before describing the system architecture of this embodiment, we will first combine... Figure 3 The structure and working principle of the traditional hydraulic braking system are explained in detail to provide a clearer understanding of the differences and advancements between the EMB system on which this invention is based and the prior art.

[0086] like Figure 3 As shown, a traditional hydraulic brake caliper mainly includes a caliper housing 301, a piston 302, a rectangular sealing ring 303, and a dust cover 304. The caliper housing 301 is a fixed support structure, with a piston mounting cavity inside. The inner wall of the piston has an annular sealing groove to accommodate the rectangular sealing ring 303. The piston 302 is located within the mounting cavity and can reciprocate axially. One end of the piston bears hydraulic pressure, and the other end abuts against a friction plate. The rectangular sealing ring 303 is located within the annular sealing groove, and its inner side contacts the outer circumferential surface of the piston 302 to form a seal. Its cross-section is rectangular, serving both sealing and return functions. The dust cover 304 is located between the caliper housing 301 and the piston 302 to prevent external impurities from entering the moving area.

[0087] like Figure 3As shown in Figure A, when braking is applied, after the driver depresses the brake pedal, hydraulic pressure acts on the inner end face of piston 302, pushing piston 302 outward and causing the friction pads to press against the brake disc to generate braking torque. During this process, the friction between the outer circumferential surface of piston 302 and rectangular sealing ring 303 causes the contact part of the sealing ring to deflect and twist, causing the rectangular sealing ring 303 to undergo elastic torsional deformation and store elastic recovery energy. Figure 3 The area indicated by the dashed circle in section A highlights the deformation state of the rectangular sealing ring 303 during braking.

[0088] like Figure 3 As shown in Figure B, in the brake release state, after the driver releases the brake pedal, the hydraulic pressure decreases, and the elastic recovery energy stored in the rectangular sealing ring 303 is released. The sealing ring recovers from its torsional deformation state to its initial state by relying on its own elastic recovery force. Since there is a contact fit between the sealing ring and the outer circumferential surface of the piston 302, the sealing ring applies a reverse force to the piston 302 during the recovery process, causing the piston 302 to retract inward, creating a release gap between the friction pad and the brake disc, thus releasing the braking torque. Figure 3 The area indicated by the dashed circle in section B highlights the state of the seal ring after restoration, and the arrow indicates the return direction of piston 302.

[0089] The aforementioned return mechanism relies on the elastic recovery of the rectangular sealing ring 303, requiring no additional active return mechanism, resulting in a simple structure. However, this mechanism has inherent limitations: First, the return amount is unstable. Temperature changes cause changes in the elastic modulus of the sealing ring, and long-term use leads to aging and hardening of the sealing ring. Factors such as brake fluid composition and sealing groove machining tolerances also affect the friction between the sealing ring and the piston, causing fluctuations in the return amount. Second, the return process is passive, lacking active and precise control capabilities. Third, insufficient return results in an excessively small gap between the friction pad and the brake disc, generating drag torque and increasing energy consumption. Fourth, increasing the return amount to reduce drag leads to a longer response time for the next braking action. In other words, the contradiction between drag and response is an inherent bottleneck of traditional hydraulic braking systems.

[0090] Unlike traditional solutions, the EMB (Electronic Brake-by-Wire) system used in this invention eliminates brake fluid and hydraulic lines. Braking is achieved by directly driving the piston via a motor, reduction gear, and lead screw. The piston's return to its original position is achieved through motor reversal, enabling active and precise control. A motor position sensor can accurately detect the rotor angle (resolution up to 0.1°), and after conversion using the lead screw lead, the piston displacement can be precisely controlled, unaffected by factors such as temperature or aging. Furthermore, the brake pedal is completely decoupled from the actuator, and the pedal feel is generated independently by the simulator. These features provide the hardware foundation for achieving precise control of dynamic target gaps in this invention.

[0091] The caliper low drag control system of this embodiment will be described in detail below with reference to the accompanying drawings.

[0092] like Figure 2 The caliper low-drag control system based on the brake-by-wire (EMB) system provided in this embodiment includes: The 201 signal acquisition module is used to acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal. The 202 dynamic clearance correction module is used to calculate the dynamic target clearance based on the brake disc temperature signal and the caliper wear state signal, and to control the disc clearance of the caliper based on the dynamic target clearance. 203 Intent fusion module, used to calculate comprehensive intent score based on the pedal opening signal, the vehicle speed signal and the road surface adhesion coefficient signal; The 204 state machine control module is used to determine the target caliper's working state according to the comprehensive intent score and the current caliper working state, following the four-level state machine switching rules with hysteresis mechanism, and output the drag torque control command corresponding to the target caliper's working state.

[0093] Specifically, the dynamic gap correction module includes a temperature compensation submodule, which has a brake disc temperature signal input terminal, a temperature compensation coefficient memory, and a temperature compensation amount output terminal. The temperature compensation coefficient memory stores temperature... Thermal expansion coefficient mapping table, material density correction factor and gap Expansion conversion coefficient; The wear compensation submodule has a contact point angle signal input terminal, a lead screw lead parameter memory, and a wear compensation output terminal. The contact point angle signal input terminal is connected to the input interface of the motor position sensor. The wear compensation submodule is equipped with a recursive least squares estimator with a forgetting factor. The adder has its first input terminal connected to the temperature compensation output terminal, its second input terminal connected to the wear compensation output terminal, and its third input terminal connected to the reference gap parameter memory. Its output terminal outputs the dynamic target gap control signal.

[0094] Specifically, the intent fusion module includes: The acceleration confirmation threshold calculation submodule has a vehicle speed signal input terminal, a road surface adhesion coefficient signal input terminal and a longitudinal acceleration signal input terminal. It internally stores the benchmark acceleration confirmation threshold and the sigmoid function parameter table. Its output terminal outputs the acceleration confirmation threshold after correction by vehicle speed, adhesion coefficient and longitudinal acceleration. The emergency retraction determination submodule has a pedal opening change rate signal input terminal, a pedal acceleration signal input terminal, a vehicle speed signal input terminal, and a road surface adhesion coefficient signal input terminal. It internally stores the reference emergency retraction threshold and jitter threshold parameters, and its output terminal outputs a valid emergency retraction indicator signal. The scoring fusion submodule has its signal input terminals connected to the output terminals of the accelerated confirmation threshold calculation submodule and the rapid settlement determination submodule, respectively. It has a multi-channel signal weighting fusion circuit inside, and its output terminal outputs the comprehensive intent score signal.

[0095] Specifically, the state machine control module includes: The state memory is used to store the current caliper operating state identifier, which is selected from one of the following: idle standby state, pre-pressure holding state, rapid approach state, and brake pressure building state. A threshold comparator has its first input connected to the output of the intent recognition unit to receive the comprehensive intent score signal, its second input connected to the up-threshold register, and its third input connected to the down-threshold register. The threshold comparator outputs a comparison result signal. A state switching controller has its input connected to the output of the threshold comparator and its output connected to the update control terminal of the state memory. The state switching controller controls the update of the working state identifier in the state memory according to the comparison result signal. It internally stores a switching logic rule table between each state. The instruction output interface has its input end connected to the output end of the state memory, and its output end outputs the drag torque control instruction corresponding to the current working state.

[0096] Example 3 Embodiment 3 of the present invention provides a vehicle including the caliper low drag control system based on the brake-by-wire EMB system described in Embodiment 2.

[0097] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A caliper low-drag control method based on a brake-by-wire (EMB) system, characterized in that, include: Acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal; The dynamic target clearance is calculated based on the brake disc temperature signal and the caliper wear status signal, and the caliper disc clearance is controlled based on the dynamic target clearance. Calculate the overall intent score based on the pedal opening signal, the vehicle speed signal, and the road surface adhesion coefficient signal; Based on the comprehensive intent score and the current caliper operating state, the target caliper operating state is determined according to the four-level state machine switching rules with hysteresis mechanism, and the drag torque control command corresponding to the target caliper operating state is output.

2. The method according to claim 1, characterized in that, The dynamic target clearance is obtained by adding the reference clearance, temperature compensation, and wear compensation. The temperature compensation is calculated based on the thermal expansion of the brake disc, and the wear compensation is calculated based on the accumulated wear displacement of the caliper friction pair during use. The formula for calculating the dynamic target clearance is: in, For dynamic target gaps, As the reference gap, This is the temperature compensation amount. This is the amount of wear compensation.

3. The method according to claim 2, characterized in that, The thermal expansion is calculated based on the current brake disc temperature, temperature-dependent thermal expansion coefficient, material density correction factor, brake disc thickness, and reference temperature. The thermal expansion is then multiplied by the gap. After the expansion conversion coefficient is applied, the thermal expansion is then limited to a preset upper and lower limit range by a saturation limiting function to obtain the temperature compensation amount; the calculation formula for the thermal expansion amount is: in, This represents the amount of thermal expansion of the brake disc in the direction perpendicular to the friction working surface. The coefficient of thermal expansion is the temperature-dependent coefficient. This is the material density correction factor. For brake disc thickness, This is the current brake disc temperature. The reference temperature is used; the formula for calculating the temperature compensation is: in, This is the gap-expansion conversion coefficient. It is a saturation limiting function. and These are the lower and upper limits of the temperature compensation, respectively.

4. The method according to claim 2, characterized in that, The wear compensation amount is obtained as follows: using a recursive least squares method with a forgetting factor, the current wear contact point angle is recursively estimated based on the actual contact point angle detected during each braking. The difference between the currently estimated wear contact point angle and the initial contact point angle is used as the cumulative wear angle increment. Then, based on the lead screw lead, the cumulative wear angle increment is converted into a displacement compensation amount to obtain the wear compensation amount. in, For the first Estimated wear contact points per braking cycle Forgetting factor, For the first The actual contact point angle detected during the second braking; the conversion formula for displacement compensation is: in, To accumulate the wear angle increment, This refers to the lead of the leadscrew.

5. The method according to claim 1, characterized in that, The process of calculating the comprehensive intent score includes: dynamically adjusting the acceleration confirmation threshold for determining acceleration intent based on the vehicle speed signal, the road surface adhesion coefficient signal, and the acquired longitudinal acceleration signal; determining the emergency stop threshold based on the vehicle speed signal and the road surface adhesion coefficient signal, and acquiring the pedal opening change rate signal and the pedal acceleration signal; when the pedal opening change rate is less than the emergency stop threshold and the absolute value of the pedal acceleration is greater than a preset jitter threshold, it is determined to be a valid emergency stop state; normalizing and weighting the acquired forward collision time signal, road slope signal, navigation prediction signal, and pedal opening signal, and combining them with the determination result of the valid emergency stop state, to obtain a comprehensive intent score with a value range of 0 to 1.

6. The method according to claim 5, characterized in that, The acceleration confirmation threshold is adjusted as follows: the baseline acceleration confirmation threshold is multiplied sequentially by the vehicle speed correction factor, the road surface adhesion correction factor, and the longitudinal acceleration correction factor to obtain the final acceleration confirmation threshold; wherein, the vehicle speed correction factor adopts the form of a sigmoid function, which approaches 1 at low speeds and approaches 0 at high speeds; the road surface adhesion correction factor decreases in value when the road surface has low adhesion to lower the threshold; and the longitudinal acceleration correction factor increases in value when the vehicle accelerates to raise the threshold.

7. The method according to claim 1, characterized in that, The four-level state machine includes an idle standby state, a pre-pressure holding state, a rapid approach state, and a braking pressure building state. The disc clearance for each state decreases sequentially, with the largest clearance in the idle standby state, a preset smaller clearance in the pre-pressure holding state, and a clearance approaching zero in the rapid approach state. The braking pressure building state is used to apply braking torque. The hysteresis mechanism is as follows: each state has an upshift threshold and a downshift threshold, and the upshift threshold for the same state is greater than the downshift threshold, with the difference between the two forming a dead zone. When switching states, if the current comprehensive intention score is greater than the upshift threshold of the current state, the state switches to a higher hysteresis state; if the current comprehensive intention score is less than the downshift threshold of the current state, the state switches to a lower hysteresis state; if the current comprehensive intention score is between the upshift threshold and the downshift threshold of the current state, the current state remains unchanged.

8. The method according to claim 1, characterized in that, The brake disc temperature signal is acquired in real time by the temperature sensor built into the EMB caliper controller, and the sensor measurement value is indirectly converted into the actual brake disc temperature through a pre-calibrated temperature model; the caliper wear status signal is obtained by detecting the motor rotation angle corresponding to the contact point during braking through the motor position sensor, and based on the change in the contact point angle during multiple braking cycles.

9. The method according to claim 1, characterized in that, The method further includes: acquiring forward collision time signal, road slope signal, navigation prediction signal, and longitudinal acceleration signal; The comprehensive intent score is calculated as follows: a basic intent value is determined based on the pedal opening signal; the basic intent value is corrected based on the forward collision time signal, wherein the forward collision time is negatively correlated with the corrected intent value, and the basic intent value increases by a preset proportion when the forward collision time is less than a preset collision risk threshold; the basic intent value is corrected based on the road slope signal, wherein the road slope is positively correlated with the corrected intent value, and the basic intent value increases by a preset proportion when the absolute value of the downhill slope exceeds a preset slope threshold; the basic intent value is corrected based on the navigation prediction signal, and the basic intent value increases by a preset amplitude when the navigation predicts a curve or traffic light ahead; and the basic intent value is corrected based on the longitudinal acceleration signal, wherein the longitudinal acceleration is positively correlated with the corrected intent value. The modified intent value is then normalized and weighted in conjunction with the results of the accelerated confirmation threshold and the emergency collection threshold to obtain the comprehensive intent score.

10. A caliper low-drag control system based on a brake-by-wire (EMB) system, characterized in that, include: The signal acquisition module is used to acquire brake disc temperature signal, caliper wear status signal, pedal opening signal, vehicle speed signal, and road surface adhesion coefficient signal; The dynamic clearance correction module is used to calculate the dynamic target clearance based on the brake disc temperature signal and the caliper wear state signal, and to control the disc clearance of the caliper based on the dynamic target clearance. The intent fusion module is used to calculate a comprehensive intent score based on the pedal opening signal, the vehicle speed signal, and the road surface adhesion coefficient signal. The state machine control module is used to determine the target caliper's working state according to the comprehensive intent score and the current caliper working state, following the four-level state machine switching rules with hysteresis mechanism, and output the drag torque control command corresponding to the target caliper's working state.

11. The system according to claim 10, characterized in that, The dynamic gap correction module includes a temperature compensation submodule, which has a brake disc temperature signal input terminal, a temperature compensation coefficient memory, and a temperature compensation amount output terminal. The temperature compensation coefficient memory stores temperature... Thermal expansion coefficient mapping table, material density correction factor and gap Expansion conversion coefficient; The wear compensation submodule has a contact point angle signal input terminal, a lead screw lead parameter memory, and a wear compensation output terminal. The contact point angle signal input terminal is connected to the input interface of the motor position sensor. The wear compensation submodule is equipped with a recursive least squares estimator with a forgetting factor. The adder has its first input terminal connected to the temperature compensation output terminal, its second input terminal connected to the wear compensation output terminal, and its third input terminal connected to the reference gap parameter memory. Its output terminal outputs the dynamic target gap control signal.

12. The system according to claim 10, characterized in that, The intent fusion module includes: The acceleration confirmation threshold calculation submodule has a vehicle speed signal input terminal, a road surface adhesion coefficient signal input terminal and a longitudinal acceleration signal input terminal. It internally stores the benchmark acceleration confirmation threshold and the sigmoid function parameter table. Its output terminal outputs the acceleration confirmation threshold after correction by vehicle speed, adhesion coefficient and longitudinal acceleration. The emergency retraction determination submodule has a pedal opening change rate signal input terminal, a pedal acceleration signal input terminal, a vehicle speed signal input terminal, and a road surface adhesion coefficient signal input terminal. It internally stores the reference emergency retraction threshold and jitter threshold parameters, and its output terminal outputs a valid emergency retraction indicator signal. The scoring fusion submodule has its signal input terminals connected to the output terminals of the accelerated confirmation threshold calculation submodule and the rapid settlement determination submodule, respectively. It has a multi-channel signal weighting fusion circuit inside, and its output terminal outputs the comprehensive intent score signal.

13. The system according to claim 10, characterized in that, The state machine control module includes: The state memory is used to store the current caliper operating state identifier, which is selected from one of the following: idle standby state, pre-pressure holding state, rapid approach state, and brake pressure building state. A threshold comparator has its first input connected to the output of the intent recognition unit to receive the comprehensive intent score signal, its second input connected to the up-threshold register, and its third input connected to the down-threshold register. The threshold comparator outputs a comparison result signal. A state switching controller has its input connected to the output of the threshold comparator and its output connected to the update control terminal of the state memory. The state switching controller controls the update of the working state identifier in the state memory according to the comparison result signal. It internally stores a switching logic rule table between each state. The instruction output interface has its input end connected to the output end of the state memory, and its output end outputs the drag torque control instruction corresponding to the current working state.

14. A vehicle, characterized in that, The caliper low drag control system includes the one described in any one of claims 10 to 13 based on the brake-by-wire (EMB) system.

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