Pitch control method based on full active suspension and related device

Abstract

The present application relates to the technical field of vehicle suspension control, in particular to a pitch control method based on a full active suspension and related equipment, the method comprising: acquiring vehicle driving state signals, vehicle body height signals, vehicle body acceleration signals, wheel acceleration signals and controller area network signals; calculating the relative speed of the vehicle body and the wheels, the vehicle body pitch angle and performing filtering processing; calculating the road roughness index and the vehicle load and dividing the levels; calculating the ceiling pitch control active torque, judging the pitch control scene and calculating the corresponding active torque, performing arbitration to obtain the original pitch control torque; correcting according to the road roughness level and the load level; distributing to the front and rear axle actuators according to the pitch angle speed direction, the front and rear axle load and the distance from the center of mass to the front and rear axle. The present application realizes full coverage of multi-scene pitch control, effectively improves the vehicle pitch control precision and driving comfort.

Description

Technical Field

[0001] This invention relates to the field of vehicle suspension control technology, and in particular to a roll control method and related equipment based on a fully active suspension. Background Technology

[0002] During vehicle operation, pitching (rolling) motion can be categorized into the following scenarios: First, encountering road damage, bumps, or depressions can easily cause pitching (rolling) motion. Second, rapid acceleration or emergency braking during vehicle operation can also cause significant pitching motion. Third, under extreme conditions, the activation of functions such as ABS (Anti-lock Braking System) or TCS (Traction Control System) can result in greater pitching motion than normal acceleration and braking. Fourth, the transition from stationary to stationary states during special conditions like starting from a standstill and braking to a complete stop can produce even greater pitching motion, which significantly impacts the user's perceived experience.

[0003] The suspension system directly connects the vehicle body and wheels, and is a core component of a vehicle. Its performance directly affects the ride comfort, handling stability, and safety. Currently, vehicle suspensions are mainly divided into three categories: passive suspension, semi-active suspension, and fully active suspension. Regarding vehicle pitch motion, passive suspension not only cannot provide active force, but also, due to its fixed damping force curve, can only passively provide fixed damping support or restoring force. It cannot adapt to complex and changing driving conditions (such as potholes, sharp turns, acceleration, and braking), thus its improvement on vehicle pitch motion is limited and cannot meet the pitch control requirements of modern vehicles. Compared to passive suspension, semi-active suspension can improve suspension performance by adjusting the damping coefficient and has more comprehensive control scenarios and strategies. However, because it cannot actively output force, it can only passively respond to road excitation by changing the damping characteristic curve through adjusting different solenoid valve openings. Therefore, its effect on suppressing vehicle pitch motion is somewhat improved compared to passive shock absorbers, but it is still far from achieving good control of vehicle pitch motion. In contrast, fully active suspension is equipped with independent actuators (such as hydraulic actuators and electric actuators), which can actively adjust the suspension stiffness and damping in real time, and even actively output control force, effectively suppressing vehicle body vibration. It is a key technology direction for improving vehicle roll control.

[0004] Currently, fully active suspension has been gradually mass-produced and applied in mid-to-high-end vehicles, but existing roll control methods still have many shortcomings, mainly in the following aspects: The control methods and strategies are too limited. Current scenarios for active suspension roll control are insufficient, and most only consider vehicle pitch motion on continuous rough roads and rapid acceleration and braking conditions during vehicle operation. For specific scenarios such as ABS / TCS triggering, starting from a standstill, and emergency braking, there is a lack of differentiated control strategies, which cannot effectively suppress vehicle pitch motion in these special scenarios.

[0005] Insufficient adaptability of control methods: Current active suspension roll control methods mainly consider ride comfort control under design load and ordinary road surface conditions, without fully considering the impact of factors such as vehicle load changes and differences in road roughness conditions on ride comfort control parameters.

[0006] The control method for torque distribution during vehicle roll motion is not precise enough: most current active suspensions do not consider the difference between front and rear loads when distributing roll control torque, and some even do not consider the direction of pitch motion when distributing torque. Torque needs to be distributed reasonably based on the vehicle load distribution and pitch motion direction.

[0007] For situations involving rapid acceleration and emergency braking of vehicles with large pitch, existing control algorithms mostly employ open-loop control algorithms, which can only offset some inertial force disturbances, resulting in poor control performance.

[0008] In summary, existing pitch control methods for fully active suspensions cannot meet the pitch control requirements under all operating conditions, and there is an urgent need for a control method with comprehensive control logic, rapid response, strong adaptability, and high control accuracy. Summary of the Invention

[0009] In view of this, embodiments of the present invention propose a pitch control method and related equipment based on fully active suspension. By constructing a multi-scenario pitch control strategy, combined with road roughness and load correction, and a main power distribution method based on load distribution, comprehensive and precise control of vehicle pitch motion is achieved.

[0010] On one hand, embodiments of the present invention provide a roll control method based on a fully active suspension, the method comprising the following steps: Acquire vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals; The relative speed between the vehicle body and the wheels and the vehicle pitch angle are calculated based on the vehicle height signal. The vehicle pitch angle is differentiated to obtain the vehicle pitch angular velocity. The vehicle pitch angular velocity is then low-pass filtered to obtain the filtered vehicle pitch angular velocity. The driving mode is then switched to the active suspension system working mode. The road roughness index is calculated and the road roughness level is classified based on the wheel acceleration signal; the load of each sub-suspension is calculated based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration; the total vehicle load is obtained by summing the loads of each sub-suspension and the load level is classified. The active pitch control torque of the roof is calculated based on the filtered vehicle pitch angular velocity. The pitch control scenario is determined based on the vehicle driving state signal and the active pitch control torque under the corresponding scenario is calculated. The original pitch control torque is obtained based on the preset priority arbitration. The original pitch control moment is corrected based on the road roughness level and the load level to obtain the corrected pitch control moment; Based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles, the corrected pitch control torque is distributed to the front and rear axle actuators.

[0011] Optionally, acquiring the vehicle driving status signal, vehicle height signal, vehicle acceleration signal, wheel acceleration signal, and controller area network signal includes: The vehicle height signal is acquired by a height sensor, with the two connection points of the height sensor located at the control arm and the subframe, respectively. The inertial measurement unit chip is used to collect six-degree-of-freedom vehicle body acceleration and angular velocity signals. The inertial measurement unit chip is horizontally arranged and located at the vehicle's center of gravity. The vehicle body acceleration signal is collected by a vehicle body acceleration sensor, and the wheel acceleration signal is collected by a wheel acceleration sensor; The system receives vehicle speed signals, brake master cylinder pressure signals, steering wheel angle signals, and door signals from the electric power steering system, integrated brake control system, and body controller via the controller area network. The system receives internal sensor signals and operating status signals from the active actuator via a private controller local area network, and sends active power request signals and relative damping request signals to the active actuator.

[0012] Optionally, the step of calculating the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, performing a differential operation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, and performing low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity includes: The relative speed between the vehicle body and the wheels is obtained by performing a differential operation on the vehicle body height signal. The unsprung acceleration is obtained by performing a second derivative operation on the vehicle height signal; The vehicle pitch angle is calculated based on the vehicle height signal and slope information, and the vehicle pitch angle is differentiated to obtain the vehicle pitch angular velocity. The vehicle pitch angular velocity is subjected to low-pass filtering to obtain the filtered vehicle pitch angular velocity.

[0013] Optionally, the step of calculating the road roughness index and classifying the road roughness level based on the wheel acceleration signal includes: The wheel acceleration signal is subjected to high-pass filtering to remove low-frequency signals and low-pass filtering to remove high-frequency signals, resulting in a filtered wheel acceleration signal. The moving average method is used to calculate the average of the squares of the acceleration of the left front wheel and the acceleration of the right front wheel over a preset time period in the past. The road roughness index is obtained by taking the square root of the average value of the squares. Road roughness levels are classified according to different thresholds based on the road roughness index.

[0014] Optionally, the step of calculating the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration, summing the loads of each sub-suspension to obtain the total vehicle load, and classifying the load levels includes: The internal pressure of the air spring is collected using an air spring pressure sensor; Read the pre-stored effective cross-sectional area, suspension lever ratio, and gravitational acceleration; Based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration, the load corresponding to each sub-suspension is calculated using the load calculation formula, which states that the load is equal to the product of the internal pressure of the air spring and the effective cross-sectional area divided by the product of the suspension lever ratio and the gravitational acceleration. The total load of the vehicle is obtained by summing the loads corresponding to the four air springs. Establish a curve showing the relationship between the total vehicle load and the internal pressure of the air spring, and correct the curve by measuring the vehicle load. The load levels are classified according to different thresholds based on the total vehicle load.

[0015] Optionally, the step of determining the pitch control scenario based on the vehicle driving state signal and calculating the pitch control active torque under the corresponding scenario includes: When the longitudinal acceleration is greater than the first longitudinal acceleration threshold, the throttle pedal opening change rate is greater than the first throttle pedal opening change rate threshold and the throttle pedal opening is greater than the first throttle pedal opening threshold, or when the throttle pedal opening change rate is greater than the second throttle pedal opening change rate threshold and the throttle pedal opening is greater than the second throttle pedal opening threshold, or when the throttle pedal opening is greater than the third throttle pedal opening threshold, the acceleration pitch control function is activated. When the longitudinal acceleration is less than the second longitudinal acceleration threshold, the brake master cylinder pressure change rate is greater than the first brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the first brake master cylinder pressure threshold, or when the brake master cylinder pressure change rate is greater than the second brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the second brake master cylinder pressure threshold, or when the brake master cylinder pressure is greater than the third brake master cylinder pressure threshold, the brake roll control function is activated. After the acceleration pitch control function or the braking pitch control function is activated, the product of the vehicle design load, the vehicle longitudinal acceleration, the vehicle center of gravity height and the first gain coefficient is used as the first part of the open-loop control torque; the product of the vehicle pitch stiffness, the vehicle theoretical pitch angle and the second gain coefficient is used as the second part of the open-loop control torque; the first part of the open-loop control torque and the second part of the open-loop control torque are added together to obtain the open-loop control torque; With the goal of eliminating the deviation between the actual pitch angle and the theoretical pitch angle, the closed-loop control torque is obtained by adjusting the closed-loop control gain coefficient and the proportional-integral-derivative adjustment parameters. The open-loop control torque is added to the closed-loop control torque to obtain the acceleration and braking pitch control active torque; When the anti-lock braking system or traction control system is activated, an interventional pitch control active torque is generated. When the vehicle speed is lower than the preset vehicle speed threshold, the start-stop tilt control active torque is generated.

[0016] Optionally, obtaining the original pitch control moment based on preset priority arbitration includes: Arbitration is performed on the active torque for roof pitch control, the active torque for acceleration and braking pitch control, the active torque for intervention pitch control, and the active torque for start-stop pitch control based on a preset priority. The preset priority is that the active torque for intervention pitch control takes precedence over the active torque for start-stop pitch control, the active torque for start-stop pitch control takes precedence over the active torque for acceleration and braking pitch control, and the active torque for acceleration and braking pitch control takes precedence over the active torque for roof pitch control. The highest priority active pitch control torque obtained from the arbitration is added to the active pitch control torque of the ceiling to obtain the original pitch control torque.

[0017] Optionally, the step of distributing the corrected pitch control torque to the front and rear axle actuators based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles includes: The direction of the main force to be applied to the front and rear axles is determined based on the direction of the filtered vehicle pitch angular velocity. Based on the front axle load, rear axle load, distance from the center of gravity to the front axle, and distance from the center of gravity to the rear axle, the active force of the front axle actuator is calculated using the front axle active force calculation formula. The front axle active force calculation formula is: the active force of the front axle actuator is equal to the product of the corrected pitch control torque and the front axle load, divided by the product of twice the sum of the distances from the center of gravity to the front and rear axles and the rear axle load. Based on the front axle load, rear axle load, distance from the center of gravity to the front axle, and distance from the center of gravity to the rear axle, the active force of the rear axle actuator is calculated using the formula for calculating the active force of the rear axle actuator. The formula for calculating the active force of the rear axle actuator is: the active force of the rear axle actuator is equal to the product of the negative corrected pitch control torque and the rear axle load and the distance from the center of gravity to the rear axle, plus the product of the rear axle load and the distance from the center of gravity to the front axle, minus the sum of the products of the front axle load and the distance from the center of gravity to the front axle, and then divided by twice the sum of the distances from the center of gravity to the front and rear axles, and the product of the distance from the center of gravity to the rear axle and the rear axle load. The driving force of the front axle actuator and the driving force of the rear axle actuator are distributed to the four actuators.

[0018] On the other hand, embodiments of the present invention provide a roll control device based on a fully active suspension, comprising: The first module is used to acquire vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals. The second module is used to calculate the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, perform differential calculation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, perform low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity, and convert the driving mode to the active suspension system working mode. The third module is used to calculate the road roughness index and classify the road roughness level based on the wheel acceleration signal; calculate the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio and the gravitational acceleration; sum the loads of each sub-suspension to obtain the total vehicle load and classify the load level. The fourth module is used to calculate the active pitch control torque of the roof based on the filtered vehicle pitch angular velocity, determine the pitch control scenario based on the vehicle driving state signal and calculate the active pitch control torque under the corresponding scenario, and obtain the original pitch control torque based on the preset priority arbitration. The fifth module is used to correct the original pitch control moment based on the road roughness level and the load level to obtain the corrected pitch control moment. The sixth module is used to distribute the corrected pitch control torque to the front and rear axle actuators based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles.

[0019] On the other hand, embodiments of the present invention provide a roll control system based on a fully active suspension, comprising: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor performs the method described above.

[0020] On the other hand, embodiments of the present invention provide a computer-readable storage medium storing a processor-executable program, which, when executed by a processor, is used to perform the above-described method.

[0021] The embodiments of the present invention have the following beneficial effects: This invention proposes a roll control method based on active suspension. For specific scenarios such as ABS / TCS triggering, stationary start-up, and emergency braking, differentiated control strategies are proposed to effectively suppress vehicle pitch motion in these special scenarios. The method fully considers the impact of vehicle load variations and differences in road roughness on roll control, and modifies the active force of roll control based on these factors, improving the adaptability of the control method. By introducing signals such as front and rear axle loads, distances from the front and rear axles to the center of gravity, and pitch velocity direction, a reasonable distribution of pitch control torque is achieved. Addressing the insufficient control effect of open-loop control algorithms, this invention introduces more influencing factors to increase the accuracy of the open-loop control algorithm, and adds a closed-loop control correction algorithm to achieve real-time correction of the active force based on the vehicle pitch angle, greatly improving control precision. Through these methods and strategies, the effect of active suspension roll control is effectively improved, significantly enhancing vehicle ride comfort. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the active suspension roll control method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the active suspension system architecture provided in an embodiment of the present invention; Figure 3 This is a flowchart of the active suspension roll control method provided in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the relationship between air spring pressure, estimated load, and actual load provided in an embodiment of the present invention; Figure 5 This is a structural block diagram of a roll control device based on a fully active suspension provided in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] It should be noted that although the device diagram shows a modular division and the flowchart illustrates a logical order, in some cases, the steps shown or described may be performed in a different order than the modular division in the device or the order shown in the flowchart. The terms "first," "second," etc., used in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing embodiments of the invention only and is not intended to limit the invention.

[0027] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the invention.

[0028] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0029] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily need to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0030] refer to Figure 1This invention provides a roll control method based on a fully active suspension, the method comprising the following steps: S100 acquires vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals; S200: Calculate the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal; perform differential calculation on the vehicle pitch angle to obtain the vehicle pitch angular velocity; perform low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity; and switch the driving mode to the active suspension system working mode. S300: Calculate the road roughness index and classify the road roughness level based on the wheel acceleration signal; calculate the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration; sum the loads of each sub-suspension to obtain the total vehicle load and classify the load level. S400, calculate the active pitch control torque of the roof based on the filtered vehicle pitch angular velocity, determine the pitch control scenario based on the vehicle driving state signal and calculate the active pitch control torque under the corresponding scenario, and obtain the original pitch control torque based on the preset priority arbitration. S500, the original pitch control moment is corrected according to the road roughness level and the load level to obtain the corrected pitch control moment; S600, based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles, distributes the corrected pitch control torque to the front and rear axle actuators.

[0031] In the signal acquisition and signal processing steps of this embodiment, the height sensor is installed between the control arm and the subframe to reflect the vehicle height information by measuring the change in suspension displacement; the IMU (Inertial Measurement Unit) chip is horizontally arranged at the vehicle's center of gravity and directly outputs six-degree-of-freedom motion signals, avoiding additional acceleration errors introduced by the installation position being off-center; the setting of a sampling frequency ≥500Hz ensures the complete capture of high-frequency road excitation information, providing sufficient time resolution for subsequent control algorithms.

[0032] By placing the height sensor between the control arm and the subframe, the vehicle height measurement directly reflects the change in suspension travel. The relative speed between the vehicle body and the wheels, obtained after differential calculation, can be used to determine the suspension motion state. The IMU chip is horizontally positioned at the center of gravity, eliminating the coupling error of the gravity component caused by the tilt of the installation posture, ensuring the measurement accuracy of pitch angle and pitch velocity. Low-pass filtering of the pitch velocity effectively suppresses the interference of high-frequency noise on the roof control algorithm, avoiding unnecessary energy consumption and mechanical wear of the actuator due to noise triggering, while retaining effective vehicle motion information in the mid-to-low frequency range, making the calculation of the roof control torque more stable and reliable.

[0033] In some embodiments, acquiring vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals includes: The vehicle height signal is acquired by a height sensor, with the two connection points of the height sensor located at the control arm and the subframe, respectively. The inertial measurement unit chip is used to collect six-degree-of-freedom vehicle body acceleration and angular velocity signals. The inertial measurement unit chip is horizontally arranged and located at the vehicle's center of gravity. The vehicle body acceleration signal is collected by a vehicle body acceleration sensor, and the wheel acceleration signal is collected by a wheel acceleration sensor; The system receives vehicle speed signals, brake master cylinder pressure signals, steering wheel angle signals, and door signals from the electric power steering system, integrated brake control system, and body controller via the controller area network. The system receives internal sensor signals and operating status signals from the active actuator via a private controller local area network, and sends active power request signals and relative damping request signals to the active actuator.

[0034] In this embodiment, the signal acquisition architecture adopts a layered sensor layout: a height sensor provides suspension geometry information, an IMU chip provides vehicle attitude information, vehicle and wheel acceleration sensors provide dynamic response information, and a CAN network (Controller Area Network) provides vehicle status information. The height sensor is positioned between the control arm and the subframe to directly measure the relative displacement of the suspension; the IMU chip is horizontally positioned at the center of gravity to ensure that the reference coordinate system for the six degrees of freedom measurement is consistent with the vehicle's center of gravity coordinate system; the proprietary CAN network is dedicated to high-speed data exchange between the active suspension control unit and the active actuators, ensuring real-time transmission of active force commands and rapid feedback of actuator status.

[0035] The layered sensor layout enables comprehensive perception of the vehicle's motion state: the combination of height sensor and IMU chip provides complete information on vehicle attitude and suspension deformation, providing accurate input for pitch angle calculation and roof control; the separate arrangement of body and wheel acceleration sensors allows for independent identification of the dynamic response of sprung and unsprung mass, providing independent data sources for road roughness estimation and load calculation; the dual network architecture of public CAN and private CAN ensures information interaction between the active suspension system and other vehicle systems (such as receiving control trigger signals such as brake pressure and throttle opening), while also ensuring high real-time performance of the active suspension's internal control loop (the active force command update cycle can be controlled within 10ms), avoiding the impact of public CAN bus congestion on control real-time performance.

[0036] In some embodiments, the step of calculating the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, performing a differential operation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, and performing low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity includes: The relative speed between the vehicle body and the wheels is obtained by performing a differential operation on the vehicle body height signal. The unsprung acceleration is obtained by performing a second derivative operation on the vehicle height signal; The vehicle pitch angle is calculated based on the vehicle height signal and slope information, and the vehicle pitch angle is differentiated to obtain the vehicle pitch angular velocity. The vehicle pitch angular velocity is subjected to low-pass filtering to obtain the filtered vehicle pitch angular velocity.

[0037] In this embodiment, the signal processing flow adopts a cascaded operation structure: the vehicle height signal is differentiated once to obtain the relative velocity (used to determine the suspension movement direction), and differentiated twice to obtain the unsprung acceleration (used for road roughness estimation); the vehicle pitch angle is differentiated to obtain the pitch angular velocity, and then low-pass filtered to obtain the filtered pitch angular velocity (used for roof control). The cutoff frequency of the low-pass filter is set according to the main energy distribution of the pitch motion, usually taking 2-3 times the vehicle pitch mode frequency as the cutoff frequency, which preserves the main information of the pitch motion while effectively suppressing high-frequency noise.

[0038] The cascaded operation structure enables multi-level utilization of signals: the same vehicle height signal is used to extract speed and acceleration information through different orders of differential operations, avoiding the installation of additional sensors; the low-pass filtering of the vehicle pitch angular velocity eliminates signal glitches caused by sensor quantization noise and high-frequency road surface excitation, making the output of the roof control torque smoother, avoiding frequent reciprocating motion of the actuator, and reducing energy consumption and mechanical wear; the filtered pitch angular velocity retains the main frequency components of the vehicle pitch motion (usually 0.5-5Hz), ensuring the effective response of the roof control to the actual pitch motion, while avoiding malfunctions caused by high-frequency noise and improving the robustness of the control system.

[0039] In some embodiments, calculating the road roughness index and classifying the road roughness level based on the wheel acceleration signal includes: S311, perform high-pass filtering on the wheel acceleration signal to remove low-frequency signals, and perform low-pass filtering on the wheel acceleration signal to remove high-frequency signals, to obtain the filtered wheel acceleration signal. S312, use the moving average method to calculate the average of the squares of the acceleration of the left front wheel and the acceleration of the right front wheel over a preset time period in the past; S313, Calculate the square root of the average value of the squares to obtain the road roughness index; S314, road roughness levels are classified according to different thresholds based on the road roughness index.

[0040] Specifically, the road roughness index is calculated using a bandpass filtering strategy. The high-pass cutoff frequency is set to 5Hz to remove low-frequency trend terms caused by vehicle acceleration and deceleration, and the low-pass cutoff frequency is set to 25Hz to remove high-frequency noise such as local tire resonance. The moving average window length is set to 2s (2000 sampling points), which ensures both statistical stability and real-time response to road condition changes.

[0041] In some embodiments, the step of calculating the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration, summing the loads of each sub-suspension to obtain the total vehicle load, and classifying the load levels includes: S321, The internal pressure of the air spring is collected by the air spring pressure sensor; S322, Read the pre-stored effective cross-sectional area, suspension lever ratio, and gravitational acceleration; S323, based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration, calculate the load corresponding to each sub-suspension using the load calculation formula. The load calculation formula is that the load is equal to the product of the internal pressure of the air spring and the effective cross-sectional area divided by the product of the suspension lever ratio and the gravitational acceleration. S324, sum the loads corresponding to the four air springs to obtain the total load of the vehicle; S325, Establish the corresponding relationship curve between the total vehicle load and the internal pressure of the air spring, and correct the corresponding relationship curve by measuring the vehicle load; S326, load levels are classified according to different thresholds based on the total load of the vehicle.

[0042] Specifically, the load estimation is based on the equivalent piston model of the air spring, which equates the air pressure inside the air spring to the supporting force. The force is converted to the wheel contact point through the leverage ratio and then divided by the gravitational acceleration to obtain the equivalent mass. The four air springs are calculated independently and then summed to obtain the estimated total load of the vehicle.

[0043] By employing a 5Hz-25Hz bandpass filter, the road roughness index effectively isolates low-frequency vehicle body movements caused by driver operation (such as pitch due to acceleration and deceleration) and high-frequency interference such as tire cavity resonance, accurately reflecting the excitation intensity of road surface unevenness. A 2-second moving average window ensures sufficient statistical confidence in the roughness estimation, while the 2-second update cycle allows for timely responses to road type changes (such as transitioning from asphalt to gravel). The load estimation method based on air spring pressure utilizes the air spring itself as a weighing sensor, eliminating the need for additional load measurement devices and reducing system cost and complexity. The correlation curve obtained from measured load correction eliminates systematic errors caused by air spring manufacturing tolerances and temperature drift, ensuring the load estimation accuracy meets the requirements of active power distribution. Dividing road roughness and vehicle load into multiple levels provides a discrete control parameter lookup table for the correction of the active power torque, simplifying real-time calculation complexity and facilitating engineering implementation.

[0044] In some embodiments, determining the pitch control scenario based on the vehicle driving state signal and calculating the corresponding pitch control active torque includes: When the longitudinal acceleration is greater than the first longitudinal acceleration threshold, the throttle pedal opening change rate is greater than the first throttle pedal opening change rate threshold and the throttle pedal opening is greater than the first throttle pedal opening threshold, or when the throttle pedal opening change rate is greater than the second throttle pedal opening change rate threshold and the throttle pedal opening is greater than the second throttle pedal opening threshold, or when the throttle pedal opening is greater than the third throttle pedal opening threshold, the acceleration pitch control function is activated. When the longitudinal acceleration is less than the second longitudinal acceleration threshold, the brake master cylinder pressure change rate is greater than the first brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the first brake master cylinder pressure threshold, or when the brake master cylinder pressure change rate is greater than the second brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the second brake master cylinder pressure threshold, or when the brake master cylinder pressure is greater than the third brake master cylinder pressure threshold, the brake roll control function is activated. After the acceleration pitch control function or the braking pitch control function is activated, the product of the vehicle design load, the vehicle longitudinal acceleration, the vehicle center of gravity height and the first gain coefficient is used as the first part of the open-loop control torque; the product of the vehicle pitch stiffness, the vehicle theoretical pitch angle and the second gain coefficient is used as the second part of the open-loop control torque; the first part of the open-loop control torque and the second part of the open-loop control torque are added together to obtain the open-loop control torque; With the goal of eliminating the deviation between the actual pitch angle and the theoretical pitch angle, the closed-loop control torque is obtained by adjusting the closed-loop control gain coefficient and the proportional-integral-derivative adjustment parameters. The open-loop control torque is added to the closed-loop control torque to obtain the active torque for acceleration, braking, and pitch control.

[0045] In this embodiment, the active pitch control torque is first calculated based on the filtered vehicle pitch angular velocity. The pitch control strategy is based on the "skylight damping" theory, introducing an idealized virtual damper fixed in inertial space into the pitch motion control; the active torque is proportional to the pitch angular velocity, with a proportionality coefficient... The damping strength of the roof control is determined. The difference between semi-active and fully active suspension is that semi-active roof control can only provide damping force in the same direction as the relative speed of the suspension (quadrants one and three), while fully active suspension can independently output active force, unrestricted by the suspension's motion state, and can output force arbitrarily in all four quadrants. However, it should be noted that when the vehicle pitch rate and wheel bounce rate are in opposite directions, the active output counter-torque's effect on suppressing vehicle pitch will be weakened. Based on a two-dimensional correction coefficient table of vehicle speed and pitch rate, adaptive adjustment of the roof control parameters is achieved.

[0046] The roof roll control strategy introduces a main torque proportional to the pitch rate, providing a counter-restoring torque when the vehicle body pitches. This is equivalent to establishing a virtual damping connection between the vehicle body and the inertial space, effectively dissipating the kinetic energy of the vehicle body's pitch motion. The fully active suspension breaks through the quadrant limitation of the semi-active suspension, and can still output control torque even when the vehicle body and wheels move in opposite directions, expanding the effective control range. Through two-dimensional correction of vehicle speed and pitch rate, the roof damping coefficient is reduced at high speeds to avoid deterioration of road isolation caused by over-control, and the damping coefficient is increased at large pitch rates to enhance motion suppression. This achieves adaptive matching between control strength and driving conditions, balancing smoothness and handling stability.

[0047] Acceleration and braking pitch control employs a three-level activation strategy: the first level identifies rapid acceleration / braking conditions by combining longitudinal acceleration with throttle / brake rate of change; the second level identifies rapid but non-limiting acceleration / deceleration operations by combining pedal rate of change with pedal opening; and the third level identifies sustained high throttle / high braking conditions solely based on pedal opening thresholds. The first part of the open-loop control, TOL1, is based on the principle of inertial force, converting the inertial torque (mAxh) generated by longitudinal acceleration into a feedforward control torque through a gain coefficient. The second part of the open-loop control, TOL2, introduces theoretical pitch angle correction, using the product of vehicle pitch stiffness and theoretical pitch angle as an additional compensation torque, thus overcoming the shortcomings of traditional open-loop control that only considers inertial force while ignoring the suspension's elastic recovery effect. The closed-loop control uses a PID algorithm, taking the deviation between the actual pitch angle and the theoretical pitch angle as input, to correct the residual error of the open-loop control in real time.

[0048] The three-level activation condition design enables progressive identification of acceleration and braking conditions: the first level targets the most severe acceleration and deceleration operations (such as rapid acceleration for overtaking and emergency braking), ensuring timely intervention of control under extreme conditions; the second level covers rapid acceleration and deceleration in daily driving (such as starting at traffic lights and slowing down while following another vehicle), avoiding over-control caused by frequent triggering of the first level; the third level addresses scenarios such as continuous acceleration on long slopes or frequent braking in congested areas, providing continuous control support. The first part of the open-loop control, TOL1, is based on inertial force feedforward, outputting compensation torque the instant longitudinal acceleration occurs, overcoming the response lag problem of roof control relying on speed feedback; the second part, TOL2, introduces theoretical pitch angle correction, considering the deformation characteristics of suspension elastic elements during longitudinal load transfer, making the open-loop control torque closer to actual needs and reducing the burden on closed-loop control; the closed-loop PID control uses the deviation between the actual and theoretical pitch angles as input, eliminating residual pitch caused by modeling errors and parameter drift in the open-loop model in real time, realizing a hierarchical control architecture of coarse and fine tuning, significantly improving pitch suppression accuracy under acceleration and braking conditions.

[0049] In some embodiments, the step of determining the pitch control scenario based on the vehicle driving state signal and calculating the pitch control active torque under the corresponding scenario further includes: When the anti-lock braking system or traction control system is activated, it generates an interventional pitch control active torque.

[0050] In this embodiment, when ABS (Anti-lock Braking System) and TCS (Traction Control System) are activated, the vehicle is under extreme adhesion conditions. The drastic fluctuations in tire longitudinal force cause the vehicle pitch motion amplitude and frequency to far exceed those under normal acceleration and braking conditions. At this time, the active suspension needs to provide the maximum available active torque Tabstcs to suppress vehicle pitch with the strongest control strength. The value of Tabstcs is usually set to the upper limit of the active actuator output or close to the upper limit to ensure that the maximum control capability of the fully active suspension is achieved under extreme conditions.

[0051] When ABS / TCS is activated, the tires are in a critical slip ratio control state. High-frequency fluctuations in longitudinal force are transmitted to the vehicle body through the suspension, causing severe pitch vibration. If only roof control or conventional acceleration and braking control are relied upon at this time, the control strength is insufficient to counteract the pitch excitation under extreme conditions. By setting ABS / TCS intervention control to the highest priority and providing maximum active torque, the active suspension applies the strongest suppression at the initial stage of vehicle pitch movement, limiting the pitch angle and pitch velocity to a very small range. This avoids severe axle load transfer caused by large vehicle pitch, thereby maintaining the stability of the tire's vertical load and indirectly supporting the slip ratio control effect of ABS / TCS, improving the overall vehicle safety and stability under extreme conditions.

[0052] In some embodiments, the step of determining the pitch control scenario based on the vehicle driving state signal and calculating the pitch control active torque under the corresponding scenario further includes: When the vehicle speed is lower than the preset vehicle speed threshold, the start-stop tilt control active torque is generated.

[0053] In this embodiment, start-stop pitch control is designed for low-speed conditions below 5 km / h, where vehicle pitch is primarily caused by inertial forces during startup or braking. Due to the extremely low speed, the relative motion speed of the suspension is small, limiting the damping force output of the semi-active suspension (damping force is proportional to speed), while the fully active suspension can independently output active force without speed limitations. The Tsp calibration employs a subjective evaluation method, where test engineers adjust the torque based on ride comfort under actual start-stop conditions until a satisfactory pitch suppression effect is achieved.

[0054] In a stationary start-up scenario, the moment the driver releases the brake pedal and presses the accelerator, the vehicle accelerates from a standstill, causing the body to pitch backward (squat). In a braking stop scenario, the vehicle decelerates from a low speed to a standstill, causing the body to pitch forward (nose-diving). In both of these scenarios, because the vehicle speed is below 5 km / h, the suspension movement speed is extremely low, and the semi-active dampers cannot provide effective damping support, resulting in large pitch amplitudes and slow decay, severely impacting ride comfort. The fully active suspension, by actively outputting the start-stop control torque Tsp, provides a counter-support torque at the initial stage of pitch movement, effectively suppressing squat and nose-diving amplitudes. The subjective evaluation calibration method optimizes for human-perceived comfort, ensuring that the start-stop control force is sufficient to suppress uncomfortable pitch while avoiding the harshness caused by over-control, achieving a significant improvement in ride quality under low-speed start-stop conditions.

[0055] In some embodiments, obtaining the original pitch control moment based on preset priority arbitration includes: Arbitration is performed on the active torque for roof pitch control, the active torque for acceleration and braking pitch control, the active torque for intervention pitch control, and the active torque for start-stop pitch control based on a preset priority. The preset priority is that the active torque for intervention pitch control takes precedence over the active torque for start-stop pitch control, the active torque for start-stop pitch control takes precedence over the active torque for acceleration and braking pitch control, and the active torque for acceleration and braking pitch control takes precedence over the active torque for roof pitch control. The highest priority active pitch control torque obtained from the arbitration is added to the active pitch control torque of the ceiling to obtain the original pitch control torque.

[0056] In this embodiment, the arbitration mechanism adopts a priority-based superposition strategy: the four control scenarios are prioritized according to ABS / TCS intervention, start-stop, acceleration / braking, and roof control. When multiple scenarios are activated simultaneously, only the torque of the scenario with the highest priority is selected as Tx, but the roof control torque Tabs is always superimposed and output. This design ensures both the control priority of extreme conditions (ABS / TCS) and the continuous provision of basic pitch suppression by roof control under all conditions. The correction strategy uses a two-dimensional discrete lookup table method, dividing road roughness and vehicle load into 5 levels each, forming 25 correction condition points. Each condition point corresponds to a set of correction coefficients (a combination of B21-B25 and B31-B35). The correction coefficients under the current condition are obtained by looking up the table, and the original torque is adjusted accordingly. Make proportional adjustments.

[0057] The priority arbitration mechanism ensures the rational allocation of control resources under conflicting operating conditions: when ABS activation is accompanied by rapid acceleration, ABS / TCS intervention takes precedence over acceleration and braking control because stability requirements in extreme safety conditions are higher than comfort requirements. The design of the always-overlapping ceiling control allows the vehicle to continuously suppress basic pitch vibrations caused by uneven road surfaces while under extreme operating conditions, avoiding abrupt changes in ride smoothness caused by either / or control switching. The design logic of the road roughness correction coefficients B21-B25 is: the higher the roughness level (the more uneven the road surface), the larger the correction coefficient, increasing the active torque to strengthen pitch suppression and compensate for the stronger excitation of the vehicle body by the rough road surface; the design logic of the vehicle load correction coefficients B31-B35 is: the higher the load level (the heavier the vehicle), the corresponding adjustment of the correction coefficient to match the differences in inertial characteristics of different vehicle weights, ensuring consistent control effects for vehicles with light and heavy loads. The two-dimensional correction lookup table method discretizes continuously changing operating parameters into a finite number of control points, significantly reducing the computational load of real-time calculations, enabling the correction strategy to be completed within a millisecond-level control cycle, meeting real-time control requirements.

[0058] In some embodiments, distributing the corrected pitch control torque to the front and rear axle actuators based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles includes: The direction of the main force to be applied to the front and rear axles is determined based on the direction of the filtered vehicle pitch angular velocity. Based on the front axle load, rear axle load, distance from the center of gravity to the front axle, and distance from the center of gravity to the rear axle, the active force of the front axle actuator is calculated using the front axle active force calculation formula. The front axle active force calculation formula is: the active force of the front axle actuator is equal to the product of the corrected pitch control torque and the front axle load, divided by the product of twice the sum of the distances from the center of gravity to the front and rear axles and the rear axle load. Based on the front axle load, rear axle load, distance from the center of gravity to the front axle, and distance from the center of gravity to the rear axle, the active force of the rear axle actuator is calculated using the formula for calculating the active force of the rear axle actuator. The formula for calculating the active force of the rear axle actuator is: the active force of the rear axle actuator is equal to the product of the negative corrected pitch control torque and the rear axle load and the distance from the center of gravity to the rear axle, plus the product of the rear axle load and the distance from the center of gravity to the front axle, minus the sum of the products of the front axle load and the distance from the center of gravity to the front axle, and then divided by twice the sum of the distances from the center of gravity to the front and rear axles, and the product of the distance from the center of gravity to the rear axle and the rear axle load. The driving force of the front axle actuator and the driving force of the rear axle actuator are distributed to the four actuators.

[0059] In this embodiment, the active force distribution follows a two-step logic of direction determination and load distribution: First, the polarity of the active force on the front and rear axles is determined based on the pitch angular velocity direction. When the pitch angular velocity is positive (vehicle pitches up), the front axle outputs a positive active force (pushing upwards) and the rear axle outputs a negative active force (pulling downwards), forming a restoring torque to suppress pitching up. Second, based on the front and rear axle loads m1 and m2 and the distances from the center of mass to the front and rear axles L1 and L2, the magnitude of the actuator forces on the front and rear axles is calculated using the torque balance equation. (Front axle force formula) Correcting torque Distribute loads according to the front axle load percentage and wheelbase geometry; Rear axle force formula The negative sign ensures that the directions are opposite, and the numerator takes into account the effects of the difference in load between the front and rear axles and the offset of the center of mass, ensuring that the torque distribution meets the torque balance constraints of the whole vehicle.

[0060] Based on the determination of the polarity of the main force in the direction of pitch angular velocity, it is ensured that the main force output by the front and rear axle actuators always forms a restoring torque opposite to the current pitch motion direction, thus achieving active pitch suppression. The torque distribution method based on the front and rear axle loads considers the impact of the actual axle load distribution on the main force demand—the axle with a larger load requires a larger main force to produce the same torque contribution, avoiding the problems of over-control of lightly loaded axles and under-control of heavily loaded axles caused by equal torque distribution. The introduction of distances L1 and L2 from the center of gravity to the front and rear axles allows the torque distribution to adapt to the differences in wheelbase and center of gravity position of different vehicle models, ensuring the cross-model universality of the distribution strategy. By rationally distributing the corrective torque Tmodify to the four actuators, each actuator receives a main force command matching its axle load and position, maximizing the generation efficiency of the vehicle's pitch control torque while avoiding overload of individual actuators and extending the service life of the actuator system.

[0061] like Figure 2 As shown, the active suspension system in this solution includes an active suspension control unit (containing an IMU chip with a built-in controller, connected to other controllers via a CAN network), four height sensors, three vehicle acceleration sensors, and four active dampers (communicating with the active suspension control unit via a proprietary CAN network). Furthermore, active suspension is typically combined with air springs; broadly speaking, the spring portion of an active suspension system is assumed to be an air spring.

[0062] in: 1) The height sensor has two connection points located at the control arm and the subframe, respectively. It measures the height displacement, calculates the unsprung velocity and the shock absorber velocity by taking the derivative, and calculates the unsprung acceleration by taking the derivative twice.

[0063] 2) The IMU chip can provide acceleration and angular velocity signals for 6 degrees of freedom of the vehicle body. The IMU chip has special requirements for the placement of the controller, the key points of which are as follows: The IMU needs to be placed horizontally and preferably at the center of gravity of the vehicle, with an acceptable distance difference of 50mm, to measure the vehicle body attitude; if the IMU is placed far away from the center of gravity, the 3 vehicle body accelerations and 3 angular velocities at the center of gravity need to be calculated by software algorithm.

[0064] 3) Other controllers include EPS (Electric Power Steering), IBC (Integrated Brake Control), BCM (Body Control Controller), etc. The common CAN signals include vehicle speed signal, brake master cylinder pressure signal, steering wheel angle signal, door signal, etc.

[0065] 4) The active actuator includes an electronic control unit that can provide the active suspension control unit with sensor and operating status signals integrated within it (such as unsprung acceleration sensor signals, voltage signals, actual active force signals, etc.), while receiving active force and relative damping request signals from the active suspension control unit.

[0066] The process of the active suspension ride comfort control method proposed in this invention is as follows: Figure 3 As shown, this active suspension ride comfort control method consists of the following parts: 1. Signal acquisition and signal processing; The raw input signals mainly include vehicle height signals collected by the height sensor, six-degree-of-freedom vehicle acceleration and angular velocity provided by the IMU chip, vehicle acceleration signals collected by the vehicle acceleration sensor, wheel acceleration signals collected by the wheel acceleration sensor, and CAN signals such as vehicle speed and driving mode. Among them, the sampling frequency of the height, acceleration, and angular velocity signals from the sensors is ≥500Hz, and most of the signals from the public CAN network have a period of 10ms.

[0067] Preliminary calculations, unit conversions, and filtering are performed on some of the key signals collected. This mainly includes: calculating the relative speed between the vehicle body and wheels based on the vehicle height differential; calculating the pitch angle based on the vehicle height and slope; and switching the driving mode to the active suspension system operating mode. Simultaneously, key signals are filtered; considering the characteristics and usage scenarios of different signals, different filtering methods are adopted to ensure that the filtered signals better meet control requirements. For example, pitch rate has a significant impact on the mid-to-low frequency range, so a low-pass filter is used, and a reasonable filter frequency is set to obtain the required mid-to-low frequency pitch and roll rate signals.

[0068] 2. Road roughness and load estimation; The active suspension control unit receives signals from the wheel acceleration sensors. After high-pass and low-pass filtering to remove low-frequency (default ≤5Hz) and high-frequency (default ≥25Hz) signals, it calculates the average of the squared accelerations of the left and right front wheels over a period of time (default 2 seconds, 2000 cycles) using a moving average method. The square root of this average is then taken to obtain the road roughness index. Based on the road roughness index, roads can be classified into different road roughness levels according to different thresholds.

[0069] The active suspension control unit calculates the load corresponding to each sub-suspension in real time using a formula based on the air spring internal pressure (p) collected by the air spring pressure sensor, the pre-stored effective cross-sectional area of ​​the air spring (s), the active suspension lever ratio (i), and the gravitational acceleration (g), ensuring the accuracy of subsequent active force calculations. The calculation formula is: The estimated total vehicle load is obtained by summing the loads of the four air springs separately; where m is the load in kg; p is the internal pressure of the air spring in Pa; s is the effective cross-sectional area of ​​the air spring in m²; i is the suspension lever ratio (preset fixed value); and g is the acceleration due to gravity, taken as 9.8 m / s². After calculating the vehicle load, the corresponding curve of vehicle load and air spring pressure can be obtained (e.g., Figure 4 As shown in the figure, the load was corrected by actual vehicle load measurement.

[0070] Based on vehicle load, vehicles can be classified into different load levels according to different thresholds.

[0071] 3. Multi-scenario tilt control strategy; 3.1 Ceiling tilt control strategy; For vehicle pitch motion caused by uneven road surface when driving on ordinary roads, the active force of the roof tilt control is used to suppress it. The working principle of the active force of the roof tilt control is similar to that of the roof pitch control mechanism of the semi-active suspension. It is mainly used to suppress the pitch motion of the vehicle body. However, the difference between the active suspension and the semi-active suspension is that since the active suspension is not limited by the motion of the actuator, it can provide active force in four quadrants. Therefore, it does not need to consider the consistency of the direction of the vehicle body and wheel speed. However, when the speed directions of the two are different, the effect of the reverse active force provided to suppress the pitch motion of the vehicle body is weaker than when the directions are the same.

[0072] Active moment for ceiling tilt control The calculation formula is as follows: ; in: The active force coefficient for controlling the longitudinal tilt of the ceiling. The pitch rate of the vehicle body.

[0073] In addition, the main force for controlling the roof tilt needs to be corrected based on vehicle speed and vehicle pitch rate (see Table 1 for reference).

[0074] Table 1: Correction coefficients for the active force of roof tilt control as a function of vehicle speed or pitch angular velocity;

[0075] 3.2 Acceleration and braking pitch control strategy; When a vehicle is accelerating or braking, it is often accompanied by a large and rapid pitching motion. Relying solely on roof tilt control cannot provide a timely response, and the control effect is difficult to guarantee. Therefore, a faster and more precise control strategy is needed.

[0076] 1) Function activation; The acceleration tilt control function is activated under the following three conditions: First, the longitudinal acceleration is greater than the threshold AxAcc, and the rate of change of the accelerator pedal opening is greater than the threshold GasGrid1 and the accelerator pedal opening is greater than the threshold Gas1. Second, the rate of change of accelerator pedal opening is greater than the threshold GasGrid2 and the accelerator pedal opening is greater than the threshold Gas2. Third, the accelerator pedal opening is greater than the threshold Gas3.

[0077] The braking roll control function is activated under the following three conditions: First, the longitudinal acceleration is less than the threshold AxBrake, and the rate of change of brake master cylinder pressure is greater than the threshold MCPGrid1 and the brake master cylinder pressure is greater than the threshold MCP1. Second, the brake master cylinder pressure change rate is greater than the threshold MCPGrid2 and the brake master cylinder pressure is greater than the threshold MCP2. Third, the brake master cylinder pressure is greater than the threshold MCP3.

[0078] 2) Calculation of active torque; When either acceleration or braking roll control is activated, the active suspension will output active force to suppress the roll motion of the vehicle body. The calculation of the active force includes both open-loop control and closed-loop control.

[0079] The open-loop control active torque is divided into two parts. The first part is similar to the traditional open-loop control part, and the calculation formula is as follows: ; Where TOL1 is the torque of the first part of the open-loop control, m is the vehicle design load, Ax is the vehicle longitudinal acceleration, h is the vehicle center of gravity height, and Gain1 is the first gain coefficient.

[0080] Compared to traditional open-loop pitch control, this method adds a correction component based on the vehicle's theoretical pitch angle, calculated as follows: ; Wherein, TOL2 is the torque of the second part of the open-loop control, PitchStiffness is the vehicle pitch stiffness, PitchAngleref is the theoretical pitch angle of the vehicle, and Gain2 is the second gain coefficient.

[0081] The sum of the two yields the open-loop control torque: TOL = TOL1 + TOL2; The control objective of the closed-loop control torque is to eliminate the deviation between the actual pitch angle and the theoretical pitch angle. Using this deviation as the calculation input, the required closed-loop control torque TCL is obtained by adjusting the closed-loop control gain coefficient and the PID adjustment parameters.

[0082] Tpitch = TOL + TCL.

[0083] 3.3 ABS / TCS intervention pitch control strategy; When ABS or TCS is activated, the vehicle's roll motion may be more severe than during acceleration and braking. In this situation, the active suspension needs to provide stiffer (even the stiffest) active torque control to suppress the vehicle's roll motion and maintain sufficient stability. The active torque provided at this time is Tabstcs.

[0084] 3.4 Start-stop tilt control strategy; During vehicle start-up and parking, the vehicle speed is relatively low (default threshold is 5 km / h). For semi-active suspension, the shock absorber speed is generally low, making it difficult to provide sufficient damping support. In contrast, active suspension has ample capacity to provide sufficient active force support. Considering the insufficient active force control window caused by longitudinal acceleration at this time, when the vehicle speed is detected to be below a certain value, the active suspension system actively provides a larger active torque to suppress pitch movement under this condition. This active torque is Tsp, which can be calibrated on a real vehicle using subjective evaluation methods.

[0085] 4. Tilting control is based on the arbitration and correction of active forces; The priority of the four control scenarios above is ABS / TCS intervention > start-stop > acceleration and braking > roof control. That is, if multiple tilt controls are activated, only the highest priority control torque will be used for control. However, it is worth noting that roof tilt control is activated in all operating conditions. This means that regardless of which tilt control function is activated, in addition to outputting the highest priority active torque, the roof tilt control torque will also be added. The calculation formula is as follows: Torigin = Tabs + Tx; Tx could be Tpitch, Tabstcs, or Tsp.

[0086] The above calculations yielded the main driving moment for the design load on a smooth road surface. However, adjustments are needed for different vehicle load conditions and road roughness levels. Therefore, we propose a correction strategy, described below: The road roughness RS is divided into 5 levels according to different thresholds: A21 (RS≤3), A22 (3<RS≤6), A23 (6<RS≤10), A24 (10<RS≤20), and A25 (RS≥20). The thresholds can be adjusted adaptively according to the measured values.

[0087] Vehicle loads are divided into five levels, A31 to A35. The specific load thresholds need to be determined after actual vehicle testing and calibration for different vehicle models.

[0088] Based on different road roughness and vehicle loads, the driving torque under a loaded smooth road surface is modified to obtain the modified torque Tmodify. The correction coefficients are shown in Tables 2 and 3.

[0089] Table 2: Correction coefficients for active pitch control moment as a function of road roughness;

[0090] Table 3: Correction coefficients for active pitch control torque as a function of vehicle load;

[0091] 5. Tilting control of main force distribution; First, the direction of the active force to be applied to the front and rear axles needs to be determined based on the pitch angular velocity direction. It can be seen that when the pitch velocity is positive, the pitch control torque should be positive, the active force on the front axle should be positive, and the active force on the rear axle should be negative. Then, by calculating the vehicle load on the front and rear axles in step 2, and distributing the active force between the front and rear axles based on the load distribution, the formula for calculating the active force on the front axle is as follows: ; The formula for calculating the main force of the rear axle is as follows: ; Where FlongF and FlongR are the driving forces of the front and rear actuators, respectively; L1 and L2 are the distances from the center of mass to the front and rear axles, respectively; and m1 and m2 are the loads on the front and rear axles, respectively.

[0092] After allocating the power using the above formula, the four actuators can be assigned a reasonable amount of active force to achieve optimal control.

[0093] See Figure 5 This invention provides a roll control device based on a fully active suspension, comprising: The first module is used to acquire vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals. The second module is used to calculate the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, perform differential calculation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, perform low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity, and convert the driving mode to the active suspension system working mode. The third module is used to calculate the road roughness index and classify the road roughness level based on the wheel acceleration signal; calculate the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio and the gravitational acceleration; sum the loads of each sub-suspension to obtain the total vehicle load and classify the load level. The fourth module is used to calculate the active pitch control torque of the roof based on the filtered vehicle pitch angular velocity, determine the pitch control scenario based on the vehicle driving state signal and calculate the active pitch control torque under the corresponding scenario, and obtain the original pitch control torque based on the preset priority arbitration. The fifth module is used to correct the original pitch control moment based on the road roughness level and the load level to obtain the corrected pitch control moment. The sixth module is used to distribute the corrected pitch control torque to the front and rear axle actuators based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles.

[0094] It is evident that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented in the present device embodiments are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0095] This invention provides a roll control system based on a fully active suspension, comprising: At least one processor; At least one memory for storing at least one program; When at least one program is executed by at least one processor, the at least one processor performs the method described above.

[0096] It is evident that the content of the above method embodiments is applicable to the present device embodiments. The specific functions implemented in the present device embodiments are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0097] Furthermore, embodiments of the present invention also disclose a computer program product or computer program stored in a computer-readable storage medium. A processor of a computer device can read the computer program from the computer-readable storage medium, and the processor executes the computer program, causing the computer device to perform the described method. Similarly, the content of the above method embodiments is applicable to this storage medium embodiment. The specific functions implemented in this storage medium embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0098] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0099] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0100] The terms "first," "second," "third," "fourth," etc. (if present) in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0101] It should be understood that in this invention, "at least one (item)" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0102] In the several embodiments provided by this invention, 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 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 system, or some features may be ignored or not executed. Furthermore, the 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.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Furthermore, the functional units in the various embodiments of the present invention 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.

[0105] 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 computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0106] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of the present invention should be within the scope of the claims of the present invention.

Claims

1. A roll control method based on fully active suspension, characterized in that, The method includes the following steps: Acquire vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals; The relative speed between the vehicle body and the wheels and the vehicle pitch angle are calculated based on the vehicle height signal. The vehicle pitch angle is differentiated to obtain the vehicle pitch angular velocity. The vehicle pitch angular velocity is then low-pass filtered to obtain the filtered vehicle pitch angular velocity. The driving mode is then switched to the active suspension system working mode. The road roughness index is calculated and the road roughness level is classified based on the wheel acceleration signal; the load of each sub-suspension is calculated based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration; the total vehicle load is obtained by summing the loads of each sub-suspension and the load level is classified. The active pitch control torque of the roof is calculated based on the filtered vehicle pitch angular velocity. The pitch control scenario is determined based on the vehicle driving state signal and the active pitch control torque under the corresponding scenario is calculated. The original pitch control torque is obtained based on the preset priority arbitration. The original pitch control moment is corrected based on the road roughness level and the load level to obtain the corrected pitch control moment; Based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles, the corrected pitch control torque is distributed to the front and rear axle actuators.

2. The method according to claim 1, characterized in that, The acquisition of vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals includes: The vehicle height signal is acquired by a height sensor, with the two connection points of the height sensor located at the control arm and the subframe, respectively. The inertial measurement unit chip is used to collect six-degree-of-freedom vehicle body acceleration and angular velocity signals. The inertial measurement unit chip is horizontally arranged and located at the vehicle's center of gravity. The vehicle body acceleration signal is collected by a vehicle body acceleration sensor, and the wheel acceleration signal is collected by a wheel acceleration sensor; The system receives vehicle speed signals, brake master cylinder pressure signals, steering wheel angle signals, and door signals from the electric power steering system, integrated brake control system, and body controller via the controller area network. The system receives internal sensor signals and operating status signals from the active actuator via a private controller local area network, and sends active power request signals and relative damping request signals to the active actuator.

3. The method according to claim 1, characterized in that, The process of calculating the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, performing a differential operation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, and performing low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity includes: The relative speed between the vehicle body and the wheels is obtained by performing a differential operation on the vehicle body height signal. The unsprung acceleration is obtained by performing a second derivative operation on the vehicle height signal; The vehicle pitch angle is calculated based on the vehicle height signal and slope information, and the vehicle pitch angle is differentiated to obtain the vehicle pitch angular velocity. The vehicle pitch angular velocity is subjected to low-pass filtering to obtain the filtered vehicle pitch angular velocity.

4. The method according to claim 1, characterized in that, The process of calculating the road roughness index and classifying the road roughness level based on the wheel acceleration signal includes: The wheel acceleration signal is subjected to high-pass filtering to remove low-frequency signals and low-pass filtering to remove high-frequency signals, resulting in a filtered wheel acceleration signal. The moving average method is used to calculate the average of the squares of the acceleration of the left front wheel and the acceleration of the right front wheel over a preset time period in the past. The road roughness index is obtained by taking the square root of the average value of the squares. Road roughness levels are classified according to different thresholds based on the road roughness index.

5. The method according to claim 1, characterized in that, The process involves calculating the load on each sub-suspension based on the internal pressure of the air spring, its effective cross-sectional area, the suspension lever ratio, and gravitational acceleration. The total vehicle load is then obtained by summing the loads of each sub-suspension and classifying them into load levels. The internal pressure of the air spring is collected using an air spring pressure sensor; Read the pre-stored effective cross-sectional area, suspension lever ratio, and gravitational acceleration; Based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio, and the gravitational acceleration, the load corresponding to each sub-suspension is calculated using the load calculation formula, which states that the load is equal to the product of the internal pressure of the air spring and the effective cross-sectional area divided by the product of the suspension lever ratio and the gravitational acceleration. The total load of the vehicle is obtained by summing the loads corresponding to the four air springs. Establish a curve showing the relationship between the total vehicle load and the internal pressure of the air spring, and correct the curve by measuring the vehicle load. The load levels are classified according to different thresholds based on the total vehicle load.

6. The method according to claim 1, characterized in that, The step of determining the pitch control scenario based on the vehicle driving state signal and calculating the pitch control active torque under the corresponding scenario includes: When the longitudinal acceleration is greater than the first longitudinal acceleration threshold, the throttle pedal opening change rate is greater than the first throttle pedal opening change rate threshold and the throttle pedal opening is greater than the first throttle pedal opening threshold, or when the throttle pedal opening change rate is greater than the second throttle pedal opening change rate threshold and the throttle pedal opening is greater than the second throttle pedal opening threshold, or when the throttle pedal opening is greater than the third throttle pedal opening threshold, the acceleration pitch control function is activated. When the longitudinal acceleration is less than the second longitudinal acceleration threshold, the brake master cylinder pressure change rate is greater than the first brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the first brake master cylinder pressure threshold, or when the brake master cylinder pressure change rate is greater than the second brake master cylinder pressure change rate threshold and the brake master cylinder pressure is greater than the second brake master cylinder pressure threshold, or when the brake master cylinder pressure is greater than the third brake master cylinder pressure threshold, the brake roll control function is activated. After the acceleration pitch control function or the braking pitch control function is activated, the product of the vehicle design load, the vehicle longitudinal acceleration, the vehicle center of gravity height and the first gain coefficient is used as the first part of the open-loop control torque; the product of the vehicle pitch stiffness, the vehicle theoretical pitch angle and the second gain coefficient is used as the second part of the open-loop control torque; the first part of the open-loop control torque and the second part of the open-loop control torque are added together to obtain the open-loop control torque; With the goal of eliminating the deviation between the actual pitch angle and the theoretical pitch angle, the closed-loop control torque is obtained by adjusting the closed-loop control gain coefficient and the proportional-integral-derivative adjustment parameters. The open-loop control torque is added to the closed-loop control torque to obtain the acceleration, braking, and pitch control active torque; When the anti-lock braking system or traction control system is activated, an interventional pitch control active torque is generated. When the vehicle speed is lower than the preset vehicle speed threshold, the start-stop tilt control active torque is generated.

7. The method according to claim 1, characterized in that, The method of obtaining the original pitch control moment based on preset priority arbitration includes: Arbitration is performed on the active torque for roof pitch control, the active torque for acceleration and braking pitch control, the active torque for intervention pitch control, and the active torque for start-stop pitch control based on a preset priority. The preset priority is that the active torque for intervention pitch control takes precedence over the active torque for start-stop pitch control, the active torque for start-stop pitch control takes precedence over the active torque for acceleration and braking pitch control, and the active torque for acceleration and braking pitch control takes precedence over the active torque for roof pitch control. The highest priority active pitch control torque obtained from the arbitration is added to the active pitch control torque of the ceiling to obtain the original pitch control torque.

8. A roll control device based on a fully active suspension, characterized in that, include: The first module is used to acquire vehicle driving status signals, vehicle height signals, vehicle acceleration signals, wheel acceleration signals, and controller area network signals. The second module is used to calculate the relative speed between the vehicle body and the wheels and the vehicle pitch angle based on the vehicle height signal, perform differential calculation on the vehicle pitch angle to obtain the vehicle pitch angular velocity, perform low-pass filtering on the vehicle pitch angular velocity to obtain the filtered vehicle pitch angular velocity, and convert the driving mode to the active suspension system working mode. The third module is used to calculate the road roughness index and classify the road roughness level based on the wheel acceleration signal; calculate the load of each sub-suspension based on the internal pressure of the air spring, the effective cross-sectional area, the suspension lever ratio and the gravitational acceleration; sum the loads of each sub-suspension to obtain the total vehicle load and classify the load level. The fourth module is used to calculate the active pitch control torque of the roof based on the filtered vehicle pitch angular velocity, determine the pitch control scenario based on the vehicle driving state signal and calculate the active pitch control torque under the corresponding scenario, and obtain the original pitch control torque based on the preset priority arbitration. The fifth module is used to correct the original pitch control moment based on the road roughness level and the load level to obtain the corrected pitch control moment. The sixth module is used to distribute the corrected pitch control torque to the front and rear axle actuators based on the filtered vehicle pitch velocity direction, front and rear axle loads, and the distance from the center of gravity to the front and rear axles.

9. A roll control system based on fully active suspension, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor performs the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a processor-executable program, characterized in that, The processor-executable program, when executed by the processor, is used to perform the method as described in any one of claims 1 to 7.

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