A performance evaluation method and system for a car's rear-wheel active steering system

Abstract

This invention relates to the field of intelligent control technology for automotive rear wheels. Specifically, it relates to a performance evaluation method and system for an automotive rear-wheel active steering system. Based on the functional requirements of the entire vehicle and the standards and requirements for vehicle dynamics performance, a complete system and testing method for evaluating the function and performance of the rear-wheel steering system are established. This includes: functional scenarios, scenario conditions, condition evaluation indicators, and evaluation methods. These serve as preliminary evaluation standards in the control strategy software development stage, enabling virtual simulation verification and rapid strategy and software evaluation and optimization. They can also serve as the basis for test conditions and test cases in the controller hardware and software integration development stage, allowing for controller-in-the-loop semi-physical simulation testing and rapid verification of the controller software and hardware. Finally, they serve as the judgment standard for bench testing of the rear-wheel active steering physical system's function and performance, vehicle calibration, and test evaluation, providing a complete evaluation of the final achieved function and performance.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology for rear wheels of automobiles, and more specifically, to a performance evaluation method and system for an active rear-wheel steering system of an automobile. Background Technology

[0002] Rear-wheel active steering systems are a key feature in high-end vehicles, enhancing low-speed maneuverability and high-speed stability. With the increasing sophistication and intelligence of domestically produced vehicles, some models have begun to feature rear-wheel active steering, and it is predicted that more models will adopt this configuration in the future. Currently, domestic automakers and component suppliers have not yet achieved mass production of rear-wheel active steering systems. Current research institutions and companies are focusing on rear-wheel steering actuators, controllers, and control strategies, with relatively little research on engineering testing and evaluation methods for rear-wheel steering systems. Rear-wheel steering, compared to front-wheel steering, requires higher safety standards.

[0003] Currently, there is a lack of a comprehensive evaluation system specifically for rear-wheel active steering systems. Developers tend to rely more on general vehicle performance and steering system standards, methods, or software functions, resulting in incompleteness and inaccuracy.

[0004] Furthermore, current testing systems are limited to final real-vehicle testing and evaluation, lacking virtual simulation and semi-physical simulation testing methods that meet the needs of the development stage. They also have significant limitations in terms of safety, cost, and time for extreme, abnormal, and other dangerous scenarios. Summary of the Invention

[0005] The purpose of this invention is to provide a performance evaluation method and system for a rear-wheel active steering system in automobiles, in order to solve the above-mentioned problems in the prior art.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a performance evaluation method for a vehicle's rear-wheel active steering system, comprising:

[0008] Obtain the current functional scenario of the vehicle, and obtain the scenario conditions of the current functional scenario based on the functional scenario. The functional scenarios include conventional functional scenarios and unconventional functional scenarios. The conventional functional scenarios include parking scenarios, low-speed driving scenarios, medium-speed driving scenarios, high-speed driving scenarios and variable-speed driving scenarios. The unconventional functional scenarios include extreme driving scenarios and abnormal scenarios.

[0009] The vehicle's driving surface conditions and corresponding vehicle driving controls are set according to the scenario and operating conditions. The vehicle driving control includes longitudinal control and steering control.

[0010] The vehicle and system status parameters are obtained through vehicle driving control. Evaluation indicators are determined based on the characteristic indicators of each status parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability and lightness indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy-saving indicators.

[0011] Acquire a dataset of evaluation metrics for vehicles without rear-turn systems and competing vehicles with rear-turn systems, set upper and lower limits for reference values ​​of feature metrics, assign weight coefficients to several performance metrics, calculate the weighted average, and finally output the performance metric scores.

[0012] In one embodiment of the present invention, the parking scenario includes a stationary rapid turning scenario, a low-speed forward rapid turning scenario, a low-speed reverse rapid turning scenario, a reversing scenario, a parallel parking scenario, and an automatic parking scenario.

[0013] Obtain the scene condition information of the current parking scenario. If the current scene condition information is a stationary rapid turning scenario, output the first control signal. The first control signal includes longitudinal control to control the vehicle speed to zero and the braking intensity to the highest, and steering control to input the turning direction with a sine wave and the amplitude to the maximum turning angle, and cycle for three periods.

[0014] If the current scenario is a low-speed forward driving and fast turning scenario or a low-speed reverse driving and fast turning scenario, then the second control signal is output. The second control signal includes longitudinal control, which controls the vehicle speed difference to not exceed 5 km / h at three speeds, and steering control, which inputs the rotation direction in a step to the maximum displacement, with a step time of several seconds, and records the time.

[0015] If the current scenario is a reversing scenario, a parallel parking scenario, or an automatic parking scenario, then the corresponding driving state of the vehicle will be tested.

[0016] In one embodiment of the present invention, the low-speed driving scenario includes a straight-line driving scenario on an uneven road surface and several turning scenarios with different path curvatures.

[0017] Obtain the scene condition information of the current low-speed driving scenario. If the current scene condition information is a straight driving scenario on an uneven road surface, then output a third control signal. The third control signal includes longitudinal control, which controls the vehicle speed to three speeds with a difference of 10km / h, and steering control, which controls straight driving.

[0018] If the current scenario is a turning scenario, a fourth control signal is output. The fourth control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 10 km / h, and steering control, which performs closed-loop control based on the corresponding turning angle of the current turning scenario.

[0019] In one embodiment of the present invention, the driving conditions of the medium-speed driving scenario and the high-speed driving scenario include straight driving on uneven road surfaces and lane-changing scenarios with several different lanes.

[0020] Obtain the current driving conditions information of medium-speed driving scenario or high-speed driving scenario. If the current driving conditions information is a straight driving scenario on an uneven road surface, output the fifth control signal. The fifth control signal includes longitudinal control for controlling the vehicle speed at three speeds with an equal difference of 20 km / h at high speed and five speeds with an equal difference of 10 km / h at medium speed, and steering control for straight driving.

[0021] If the current scenario is a lane change condition, a sixth control signal is output. The sixth control signal includes longitudinal control, which controls the vehicle's high-speed speed with three speeds with an equal difference of 20 km / h, and medium-speed speed with five speeds with an equal difference of 10 km / h. Steering control is single-lane or multi-lane lane change control.

[0022] In one embodiment of the present invention, the scenario conditions of the high-speed driving scenario further include sinusoidal continuous steering conditions;

[0023] The system acquires sinusoidal continuous steering condition information in the current high-speed driving scenario and outputs a seventh control signal. The seventh control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 20 km / h, and steering control, which inputs the steering wheel angle sinusoidally at a fixed frequency each time, and controls the steering wheel angle to achieve the maximum lateral acceleration.

[0024] In one embodiment of the present invention, the variable speed driving scenario includes a constant circle acceleration / deceleration condition and a constant angle acceleration / deceleration condition.

[0025] Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition information is a fixed circle acceleration and deceleration condition, then output the eighth control signal. The eighth control signal includes longitudinal control to control the vehicle to accelerate and decelerate at a certain acceleration, and steering control to control the vehicle to drive at a fixed radius.

[0026] If the current scenario is a fixed-angle acceleration / deceleration condition, then the ninth control signal is output. The ninth control signal includes longitudinal control, which controls the vehicle to accelerate or decelerate at a certain acceleration, and steering control, which controls the steering wheel to drive at a fixed angle.

[0027] In one embodiment of the present invention, the extreme driving scenario includes the extreme conditions of cornering stability, cornering rapid acceleration and deceleration, straight-line emergency avoidance, cornering rapid step limit, and slalom limit.

[0028] Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition is the cornering stability limit condition or the cornering rapid acceleration and deceleration limit condition, output the tenth control signal. The tenth control signal includes longitudinal control to control the vehicle to enter the corner at an increased speed, or to increase the speed in the corner, and steering control to control the steering wheel angle according to the cornering path, and the speed increases until the vehicle reaches the stability limit.

[0029] If the current scenario is a straight-line emergency avoidance limit or a cornering rapid step limit, then the eleventh control signal is output. The eleventh control signal includes longitudinal control to control the vehicle to drive at a constant speed and steering control to control the steering wheel angle with a step input until the vehicle reaches the stable limit.

[0030] If the current scenario is a serpentine cone obstacle course, then the tenth control signal is output. The tenth control signal includes longitudinal control to control the vehicle to travel at a constant speed and steering control to control the steering wheel to pass through the cones at the maximum speed.

[0031] In one embodiment of the present invention, the acquisition of vehicle state parameters through vehicle driving control includes:

[0032] Step 1: Obtain steering wheel angle, steering wheel torque, left and right front wheel angles, rack displacement value, rack movement speed value, left and right rear wheel angles, and vehicle speed controlled by the rear steering controller rack.

[0033] Step 2: Obtain the current scene conditions. If the current scene conditions are parking scenarios, then based on Step 1, obtain the center of gravity trajectory, the outer wheel ground contact imprint information, and the rear turn system noise value.

[0034] Step 3: If the current scenario is a low-speed driving scenario, a medium-speed driving scenario, a high-speed driving scenario, a variable-speed driving scenario, or an extreme driving scenario, then based on Step 1, obtain the vehicle roll angle and the center of gravity slip angle.

[0035] Step 4: If the current scenario is an abnormal scenario, then based on step 3, obtain the vehicle abnormal information and parameters.

[0036] In one embodiment of the present invention, the score value of the final output performance index includes:

[0037]

[0038] In the formula, Let X be the score of a certain evaluation indicator, and let X be the experimental value of the characteristic indicator. This represents the upper limit of the experimental value of the characteristic index. Lower limit of experimental values ​​for characteristic indicators;

[0039]

[0040] In the formula, This is the score for this experiment. … The score for a certain evaluation indicator. … This refers to the weighting coefficient corresponding to the score of a certain evaluation indicator.

[0041] Secondly, the present invention also provides a performance evaluation system for a vehicle's rear-wheel active steering system, comprising a scenario definition module, a virtual scenario and vehicle simulation module, a rear-wheel steering system controller module, a rear-wheel steering system actuator module, a test data analysis module, and an evaluation value calculation module connected to a main control device.

[0042] The scenario definition module is used to obtain the current functional scenario of the vehicle and obtain the scenario conditions of the current functional scenario based on the functional scenario.

[0043] The virtual scene and vehicle simulation module is used to set the road conditions of the vehicle and the corresponding vehicle driving control according to the scene conditions. The vehicle driving control includes longitudinal control and steering control.

[0044] The rear wheel steering system controller module is used to receive status signals from the vehicle simulation module and the rear wheel steering system actuator module, and output the calculated control commands to the rear wheel steering system actuator, while simultaneously feeding back the status signals of the rear wheel steering system to the vehicle simulation module.

[0045] The rear wheel steering system actuator module is used to receive signals from the rear wheel steering system controller module and perform execution actions, while feeding back the status parameters of the rear wheel steering system actuator module to the rear wheel steering system controller module.

[0046] The test data analysis module is used to acquire the state parameters of the vehicle and system through vehicle driving control, and determine the evaluation indicators based on the characteristic indicators of each state parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy saving indicators.

[0047] The evaluation value calculation module is used to obtain the dataset of evaluation indicators for vehicles without a rear-turn system and vehicles with a rear-turn system. Based on the dataset, it sets the upper and lower limits of the reference values ​​of the feature indicators, sets the weight coefficients for several performance indicators, calculates the weighted average value, and finally outputs the score value of the performance indicators.

[0048] The main control device is used to execute the above-mentioned performance evaluation method for a vehicle rear-wheel active steering system.

[0049] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0050] Based on the functional requirements of the entire vehicle and the standards and requirements for vehicle dynamics performance, this system establishes a comprehensive evaluation system and testing method for the functions and performance of the rear-wheel steering system. This includes: functional scenarios, scenario conditions, condition evaluation indicators, and evaluation methods. These serve as preliminary evaluation standards in the control strategy software development phase, enabling virtual simulation verification and rapid evaluation and optimization of strategies and software.

[0051] Secondly, it can serve as the basis for test conditions and test cases during the hardware and software integration development phase of the controller, enabling semi-physical simulation testing of the controller in the loop, rapid verification of the controller software and hardware, and serving as the judgment standard for bench testing of the rear-wheel active steering system's functions and performance, vehicle calibration, and test evaluation, thus providing a complete evaluation of the final achieved functions and performance. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The naming or numbering of steps in this application does not imply that the steps in the method flow must be executed in the chronological / logical order indicated by the naming or numbering. The execution order of named or numbered process steps can be changed according to the desired technical objective, as long as the same or similar technical effect is achieved.

[0056] The module divisions described in this application are logical; in practical applications, different division methods may be used. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed. Independently described modules or sub-modules may or may not be physically separated; they may be implemented in software or hardware. Some modules or sub-modules may be implemented in software, with the processor calling the software to implement the functionality of these modules or sub-modules, while other modules or sub-modules may be implemented in hardware, such as through hardware circuitry. Furthermore, some or all of the modules can be selected to achieve the purpose of this application's solution, depending on actual needs.

[0057] This invention provides a performance evaluation method for a vehicle's rear-wheel active steering system, comprising:

[0058] Obtain the current functional scenario of the vehicle, and obtain the scenario conditions of the current functional scenario based on the functional scenario;

[0059] Specifically, the functional scenarios of vehicles equipped with rear-wheel active steering systems are defined and divided into two categories: conventional functional scenarios and unconventional functional scenarios. The conventional functional scenarios include parking scenarios, low-speed driving scenarios, medium-speed driving scenarios, high-speed driving scenarios, and variable-speed driving scenarios. The unconventional functional scenarios include extreme driving scenarios and abnormal scenarios. Furthermore, the functional scenarios are further refined to more specific scenario conditions.

[0060] The vehicle driving road conditions and corresponding vehicle driving control are set according to the scenario conditions. The vehicle driving control includes longitudinal control and steering control.

[0061] The vehicle's state parameters are obtained through vehicle driving control, and evaluation indicators are determined based on the characteristic indicators of each state parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability and lightness indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy-saving indicators.

[0062] Among them, "scenario conditions" are more precisely defined vehicle driving and usage conditions under the functional scenario classification. Scenario conditions define the specific road surface, surrounding environment and weather, vehicle speed, steering wheel position, accelerator and brake pedals, and gear position used by the user while driving the vehicle. This allows for more accurate and consistent testing and evaluation of the vehicle's corresponding functional and non-functional aspects.

[0063] Acquire the dataset of evaluation indicators for vehicles without rear-turn systems and vehicles under test with rear-turn systems, set the upper and lower limits of reference values ​​for feature indicators, set weight coefficients for several performance indicators, calculate the weighted average, and finally output the performance indicator scores.

[0064] In one exemplary embodiment of the present invention, the functional scenarios include conventional functional scenarios and unconventional functional scenarios. The conventional functional scenarios include parking scenarios, low-speed driving scenarios, medium-speed driving scenarios, high-speed driving scenarios, and variable-speed driving scenarios. The unconventional functional scenarios include extreme driving scenarios and abnormal scenarios.

[0065] The parking scenario refers to situations where the vehicle is parked and the speed does not exceed 15km / h, such as garages, parking lots, and complex roads. In this scenario, the main evaluation is the maneuverability and steering ease of the vehicle with the rear-wheel steering system.

[0066] The low-speed driving scenario refers to the scenario where the vehicle is driving steadily on urban and rural roads at a speed range of 10km / h-30km / h. In this scenario, the main evaluation is the maneuverability, steering ease and sensitivity of the rear-wheel steering system.

[0067] The medium-speed driving scenario refers to the scenario in which the vehicle is driving stably at a speed range of 30km / h-80km / h on regular and expressways in urban areas. In this scenario, the main evaluation is the handling, stability and driving style of the vehicle with the rear-wheel steering system.

[0068] The high-speed driving scenario refers to a scenario where the vehicle is traveling at a speed of 80 km / h or higher and maintaining a stable speed on urban expressways or highways. In this scenario, the main evaluation is the handling, stability, and driving style of the vehicle with the rear-wheel steering system.

[0069] The variable speed driving scenario refers to the driving scenario in which the vehicle accelerates and decelerates at high speed in a curve. In this scenario, the handling and stability of the vehicle with the rear wheel steering system are mainly evaluated.

[0070] The mode switching scenario refers to the scenario in which the driver switches between different driving modes while the vehicle is in motion. In this scenario, the main evaluation is the function of the vehicle's rear wheel steering system and the continuity of the resulting performance changes, which is mainly accomplished through subjective evaluation.

[0071] Extreme driving scenarios refer to test conditions aimed at pushing vehicles to their limits, such as cornering at medium to high speeds, emergency avoidance maneuvers, and other tests designed to test vehicle limits, including slalom and fishhook tests. These scenarios primarily evaluate the effectiveness of the vehicle's rear-steering system in improving performance at these limits. Testing in these scenarios typically involves high risks, requires sophisticated facilities, vehicles, and drivers, and involves significant costs and timelines. Therefore, extreme driving scenarios can utilize virtual simulation or a hybrid hardware-in-the-loop (HIL) simulation for initial testing, evaluation, and optimization of early-stage development solutions, followed by final validation on a real vehicle.

[0072] Virtual simulation and hardware-in-the-loop simulation can use professional simulation software to create virtual vehicle models, road scenarios, and driving models in the absence of real vehicles and real roads. This is used to simulate extreme driving scenarios. At the same time, virtual or real rear-wheel active steering physical and control systems can be used to evaluate the functionality, performance, and stability of the rear-wheel active steering system.

[0073] Abnormal scenarios refer to situations where the vehicle experiences abnormalities in the road surface, tires, or other systems of the rear-wheel steering system or other vehicles under various driving conditions. These scenarios primarily evaluate the safety performance of the vehicle's rear-wheel steering system.

[0074] Similar to extreme scenarios, virtual or semi-physical simulation methods are also recommended for this scenario.

[0075] In one embodiment of the present invention, the parking scenario includes a stationary rapid turning scenario, a low-speed forward rapid turning scenario, a low-speed reverse rapid turning scenario, a reversing scenario, a parallel parking scenario, and an automatic parking scenario.

[0076] Obtain the current parking scenario's scenario conditions information. If the current scenario conditions information is a stationary rapid turning scenario, then output the first control signal. The first control signal includes longitudinal control, which controls the vehicle speed to zero and the braking intensity to the highest level; and steering control, which rotates the steering wheel with a sine input, the amplitude of which is the maximum turning angle, and cycles for three periods, with periods of 2, 4, and 10 seconds.

[0077] If the current scenario is a low-speed forward rapid turning scenario or a low-speed reverse rapid turning scenario, then the second control signal is output. The second control signal includes longitudinal control for controlling the vehicle speed difference to not exceed 5 km / h at three speeds, and steering control for step input of the rotation direction to the maximum displacement, with a step time of 1000 seconds and a recording time of 3 seconds.

[0078] Among them, the longitudinal control for the low-speed forward rapid turning scenario and the low-speed reverse rapid turning scenario can be 5, 10, and 15 km / h respectively, with a difference not exceeding ±5%; and -5, -10, and -15 km / h respectively, with a difference not exceeding ±5%.

[0079] If the current scenario is a reversing scenario, a parallel parking scenario, or an automatic parking scenario, then the corresponding driving state of the vehicle will be tested.

[0080] Specifically, in the reversing scenario, longitudinal control is to keep the vehicle speed below 10 km / h, and steering control is to use a closed-loop control system based on a standard reversing parking space. In the parallel parking scenario, longitudinal control is to keep the vehicle speed below 10 km / h, and steering control is to use a closed-loop control system based on a quasi-parallel parking space.

[0081] In one exemplary embodiment of the present invention, the low-speed driving scenario includes a straight-line driving scenario on an uneven road surface and several turning scenarios at different angles.

[0082] Obtain the scene condition information of the current low-speed driving scenario. If the current scene condition information is a straight driving scenario on an uneven road surface, then output a third control signal. The third control signal includes longitudinal control, which controls the vehicle speed to three speeds with a difference of 10km / h, and steering control, which controls straight driving.

[0083] If the current scenario is a turning scenario, a fourth control signal is output. The fourth control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 10 km / h, and steering control, which performs closed-loop control based on the corresponding turning angle of the current turning scenario.

[0084] In this embodiment, the vehicle speed in the straight-line driving scenario on uneven road surfaces and the turning scenario at several different angles can be controlled to be 15, 25 and 35 km / h.

[0085] In this embodiment, several different turning scenarios are divided into 45-degree turning scenarios, 90-degree turning scenarios, 135-degree turning scenarios, and 180-degree turning scenarios.

[0086] In the actual simulation, the steering control for a 45-degree turn is a closed-loop control based on the path of a left / right turn at a 45-degree intersection, with a radius of 50m; the steering control for a 90-degree turn is a closed-loop control based on the path of a left / right turn at a crossroads, with a radius of 50m; the steering control for a 135-degree turn is a closed-loop control based on the path of a left / right turn at a 135-degree intersection, with R=50m. The steering control for a 180-degree turn is a closed-loop control based on the path at the beginning of the intersection, with the vehicle traveling on the far left before the U-turn, and the width defined according to the opposite single-lane, two-lane, or three-lane configuration.

[0087] In one exemplary embodiment of the present invention, the driving conditions of the medium-speed driving scenario and the high-speed driving scenario include straight driving on uneven road surfaces and lane-changing scenarios with several different lanes.

[0088] Obtain the current driving conditions information of medium-speed driving scenario or high-speed driving scenario. If the current driving conditions information is a straight driving scenario on an uneven road surface, output the fifth control signal. The fifth control signal includes longitudinal control for controlling the vehicle speed at three speeds with an equal difference of 20 km / h at high speed and five speeds with an equal difference of 10 km / h at low speed, and steering control for straight driving.

[0089] If the current scenario is a lane change condition, a sixth control signal is output. The sixth control signal includes longitudinal control, which controls the vehicle's high-speed speed to three speeds with a difference of 20 km / h, and low-speed speed to five speeds with a difference of 10 km / h. Steering control is single-lane or multi-lane lane change control.

[0090] Specifically, for medium-speed driving scenarios (100, 120, 140 km / h), the difference should not exceed ±5%. For speeds of 40, 50, 60, 70, 80 km / h, the difference should not exceed ±5%. For high-speed driving scenarios (100, 120, 140 km / h), the difference should not exceed ±5%.

[0091] The lane change conditions for different lanes include single-lane lane change, two-lane lane change, continuous lane change, and ramp entry / exit conditions.

[0092] Specifically, the steering control for single-lane lane changes follows a single lane change path, switching from the current lane to the left / right lane. For two-lane lane changes, the steering control also follows a single lane change path, switching from the current lane to the second left / right lane. For continuous lane changes, the steering control follows a double lane change path, switching from the current lane to the left / right lane and then back to the original lane.

[0093] In one exemplary embodiment of the present invention, the high-speed driving scenario further includes a sinusoidal continuous steering scenario;

[0094] The system acquires sinusoidal continuous steering condition information in the current high-speed driving scenario and outputs a seventh control signal. The seventh control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 20 km / h, and steering control, which inputs the steering wheel angle sinusoidally at a fixed frequency each time, and controls the steering wheel angle to achieve the maximum lateral acceleration.

[0095] Specifically, the sinusoidal continuous steering condition is as follows: longitudinal control: vehicle speeds of 100, 120, and 140 km / h, with a difference not exceeding ±5%. Steering control: each time, a sinusoidal input of the steering wheel angle is made at a fixed frequency, selected within the range of 0.2Hz to 5Hz. The steering wheel angle is based on achieving the maximum lateral acceleration, with reference lateral accelerations of 0.2g, 0.3g, and 0.4g.

[0096] It also includes ADAS activation status, steering control: vehicle speed ADAS system control, and steering control: vehicle speed ADAS system control.

[0097] In one exemplary embodiment of the present invention, the variable speed driving scenario includes a constant circle acceleration / deceleration condition and a constant angle acceleration / deceleration condition;

[0098] Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition information is a fixed circle acceleration and deceleration condition, then output the eighth control signal. The eighth control signal includes longitudinal control to control the vehicle to accelerate and decelerate at a certain acceleration, and steering control to control the vehicle to drive at a fixed radius.

[0099] Specifically, in the constant circle acceleration / deceleration condition, longitudinal control: The vehicle speed is increased or decreased with different initial speeds and rates in the curve, and the acceleration can be automatically determined based on different situations. Steering control: Control the steering wheel to keep the vehicle traveling along a fixed radius, selectable as 30m, 40m, 60m, or 100m.

[0100] If the current scenario is a fixed-angle acceleration / deceleration condition, then the ninth control signal is output. The ninth control signal includes longitudinal control, which controls the vehicle to accelerate or decelerate at a certain acceleration, and steering control, which controls the steering wheel to drive at a fixed angle.

[0101] Specifically, in the constant-angle acceleration / deceleration condition, longitudinal control involves increasing the vehicle speed at different initial speeds and rates within a curve. The acceleration can be determined automatically based on different conditions, such as 0.2, 0.5, 1, or 2 m / s², or 1, 2, 4, 6, or 8 m / s². Steering control involves fixing the steering wheel at a defined angle, which can be determined according to the specific site conditions, such as 45, 60, 90, or 120 degrees.

[0102] In one exemplary embodiment of the present invention, the extreme driving scenario includes the following scenarios: cornering stability extreme scenario, cornering rapid acceleration and deceleration extreme scenario, straight-line emergency avoidance extreme scenario, cornering rapid step extreme scenario, and slalom extreme scenario.

[0103] Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition is the cornering stability limit condition or the cornering rapid acceleration and deceleration limit condition, output the tenth control signal. The tenth control signal includes longitudinal control to control the vehicle to enter the corner at an increased or decreased speed, or to increase or decrease the speed in the corner, and steering control to control the steering wheel to rotate to the limit angle.

[0104] The road surface conditions can be changed to dry and flat road surface / wet and slippery road surface / icy and snowy road surface. The road path is tangent to the straight line, and the curve radius is 50m.

[0105] The cornering stability limit conditions specifically involve longitudinal control: entering the corner at a gradually increasing, stable initial speed; entering the corner at a defined speed and gradually increasing the speed within the corner; or entering the corner at a defined speed and gradually decreasing the speed within the corner.

[0106] Extreme acceleration and deceleration conditions in corners: Rapidly accelerate to full throttle in a corner until the vehicle's stability limit is reached. Enter the corner at a defined speed, then rapidly brake to full throttle in the corner until the vehicle's stability limit is reached. Steering control: Keep the steering wheel stationary until the limit is reached.

[0107] If the current scenario is a straight-line emergency avoidance limit or a cornering rapid step limit, then the eleventh control signal is output. The eleventh control signal includes longitudinal control to control the vehicle to drive at a constant speed and steering control to control the steering wheel to rotate in one direction at a certain speed.

[0108] Specifically, longitudinal control: maintain a constant speed at medium to high speeds, with a difference not exceeding ±5%. Steering control: steer rapidly to the left and right respectively to reach the vehicle's limits.

[0109] If the current scenario is a slalom extreme condition, then the tenth control signal is output. The tenth control signal includes longitudinal control to control the vehicle to travel at a constant speed and steering control to control the steering wheel to rotate back and forth at a certain speed.

[0110] One exemplary embodiment of the present invention describes obtaining vehicle state parameters through vehicle driving control, including:

[0111] Step 1: Obtain steering wheel angle, steering wheel torque, left and right front wheel angles, rack displacement value, rack movement speed value, left and right rear wheel angles, and vehicle speed controlled by the rear steering controller rack.

[0112] Step 2: Obtain the current scene conditions. If the current scene conditions are parking scenarios, then based on Step 1, obtain the center of gravity trajectory, the outer wheel ground contact imprint information, and the rear turn system noise value.

[0113] Step 3: If the current scenario is a low-speed driving scenario, a medium-speed driving scenario, a high-speed driving scenario, a variable-speed driving scenario, or an extreme driving scenario, then based on Step 1, obtain the vehicle roll angle and the center of gravity slip angle.

[0114] Step 4: If the current scenario is an abnormal scenario, then based on step 3, obtain the vehicle abnormal information and parameters.

[0115] In one embodiment of the present invention, for each key indicator, combined with the target range of the corresponding indicators for vehicles without rear-turn systems, upper and lower limits of reference values ​​for each characteristic indicator are established, and the evaluation scoring formula includes the following:

[0116]

[0117] In the formula, Let X be the score of a certain evaluation indicator, and let X be the experimental value of the characteristic indicator. This represents the upper limit of the experimental value of the characteristic index. Lower limit of experimental values ​​for characteristic indicators;

[0118]

[0119] In the formula, This is the score for this experiment. … The score for a certain evaluation indicator. … This refers to the weighting coefficient corresponding to the score of a certain evaluation indicator.

[0120] Secondly, various vehicle models equipped with rear-wheel active steering systems can be tested to obtain evaluation indicators for each model. These indicators can then be compiled and used for individual comparisons and comprehensive analysis based on vehicle dynamics principles and subjective evaluations. Indicator comparisons can be displayed using bar charts.

[0121] In this embodiment, the scenarios corresponding to the mobility and ease of use index are parking scenarios and low-speed driving scenarios, and the corresponding characteristic indicators are minimum turning radius, number of steering wheel turns, maximum steering wheel torque, center zone steering torque, and steering wheel work.

[0122] The stable safety indicators correspond to the following scenarios: variable speed driving, extreme driving, and abnormal scenarios. The corresponding characteristic indicators are understeer gradient, neutral steering point, maximum lateral acceleration, maximum vehicle speed, front and rear axle sideslip angles, center of gravity sideslip angle, and yaw rate.

[0123] The control indicators correspond to the following scenarios: high-speed driving, high-speed driving, and variable-speed driving. The corresponding characteristic indicators are: yaw rate gain, yaw rate overshoot, steering sensitivity, yaw damping, roll damping, frequency corresponding to lateral acceleration gain -3dB, lateral acceleration response time, lateral acceleration overshoot, rear wheel steering angle steady-state response time, rear rack hysteresis time, and rear wheel steering angle overshoot.

[0124] The vibration and noise index is based on the scenario of variable speed driving, and the corresponding characteristic indexes are sound pressure level (dB) and sound quality index.

[0125] The energy-saving index is based on the typical comprehensive driving conditions of a vehicle, which will not be elaborated upon in this invention.

[0126] like Figure 1As shown, the present invention also provides a performance evaluation system for a vehicle's rear-wheel active steering system, including a scenario definition module, a virtual scenario and vehicle simulation module, a rear-wheel steering system controller module, a rear-wheel steering system actuator module, a test data analysis module, and an evaluation value calculation module connected to the main control device.

[0127] The scenario definition module is used to obtain the current functional scenario of the vehicle and obtain the scenario conditions of the current functional scenario based on the functional scenario.

[0128] The virtual scene and vehicle simulation module is used to set the road conditions where the vehicle is located and the corresponding vehicle driving control according to the scene conditions. The vehicle driving control includes longitudinal control and steering control.

[0129] The rear wheel steering system controller module is used to receive status signals from the vehicle simulation module and the rear wheel steering system actuator module, calculate control commands according to the built-in algorithm software of the controller, output the rear wheel steering system actuator, and synchronously feed back the status signals of the rear wheel steering system to the vehicle simulation module.

[0130] The rear wheel steering system actuator module is used to receive signals from the rear wheel steering system controller module and perform actions, while feeding back the status parameters of the rear wheel steering system actuator module to the rear wheel steering system controller module.

[0131] The test data analysis module is used to obtain the vehicle's state parameters through vehicle driving control, and determine the evaluation indicators based on the characteristic indicators of each state parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy-saving indicators.

[0132] The evaluation value calculation module is used to obtain the evaluation index datasets of vehicles without rear-turn systems and competing vehicles with rear-turn systems. Based on the dataset, it sets the upper and lower limits of the reference values ​​of the feature indicators, sets the weight coefficients for several performance indicators, calculates the weighted average, and finally outputs the score value of the performance indicators.

[0133] The main control device is used to execute the above-mentioned performance evaluation method for a vehicle rear-wheel active steering system.

[0134] In addition, it also includes the necessary test management and communication modules and real load simulation modules to perform normal communication transmission and simulation of real-world scenarios.

[0135] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A performance evaluation method for a vehicle's rear-wheel active steering system, characterized in that, include: Obtain the current functional scenario of the vehicle, and obtain the scenario conditions of the current functional scenario based on the functional scenario. The functional scenarios include conventional functional scenarios and unconventional functional scenarios. The conventional functional scenarios include parking scenarios, low-speed driving scenarios, medium-speed driving scenarios, high-speed driving scenarios and variable-speed driving scenarios. The unconventional functional scenarios include extreme driving scenarios and abnormal scenarios. The vehicle's driving surface conditions and corresponding vehicle driving controls are set according to the scenario and operating conditions. The vehicle driving control includes longitudinal control and steering control. The vehicle and system status parameters are obtained through vehicle driving control. Evaluation indicators are determined based on the characteristic indicators of each status parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability and lightness indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy-saving indicators. Acquire a dataset of evaluation metrics for vehicles without rear-turn systems and competing vehicles with rear-turn systems, set upper and lower limits for reference values ​​of feature metrics, assign weight coefficients to several performance metrics, calculate the weighted average, and finally output the performance metrics scores. The parking scenarios include the following scenarios: quick turn in place, quick turn while moving forward at low speed, quick turn while reversing at low speed, reversing, parallel parking, and automatic parking. Obtain the scene condition information of the current parking scenario. If the current scene condition information is a stationary rapid turning scenario, output the first control signal. The first control signal includes longitudinal control to control the vehicle speed to zero and the braking intensity to the highest, and steering control to input the turning direction with a sine wave and the amplitude to the maximum turning angle, and cycle for three periods. If the current scenario is a low-speed forward driving and fast turning scenario or a low-speed reverse driving and fast turning scenario, then the second control signal is output. The second control signal includes longitudinal control, which controls the vehicle speed difference to not exceed 5 km / h at three speeds, and steering control, which inputs the rotation direction in a step to the maximum displacement, with a step time of several seconds, and records the time. If the current scenario is a reversing scenario, a parallel parking scenario, or an automatic parking scenario, then the corresponding driving state of the vehicle will be tested.

2. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The low-speed driving scenario includes straight-line driving on uneven roads and several turning scenarios with different path curvatures. Obtain the scene condition information of the current low-speed driving scenario. If the current scene condition information is a straight driving scenario on an uneven road surface, then output a third control signal. The third control signal includes longitudinal control, which controls the vehicle speed to three speeds with a difference of 10km / h, and steering control, which controls straight driving. If the current scenario is a turning scenario, a fourth control signal is output. The fourth control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 10 km / h, and steering control, which performs closed-loop control based on the corresponding turning angle of the current turning scenario.

3. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The medium-speed driving scenario and the high-speed driving scenario include straight driving on uneven road surfaces and lane changing scenarios in several different lanes. Obtain the current driving conditions information of medium-speed driving scenario or high-speed driving scenario. If the current driving conditions information is a straight driving scenario on an uneven road surface, output the fifth control signal. The fifth control signal includes longitudinal control for controlling the vehicle speed at three speeds with an equal difference of 20 km / h at high speed and five speeds with an equal difference of 10 km / h at medium speed, and steering control for straight driving. If the current scenario is a lane change condition, a sixth control signal is output. The sixth control signal includes longitudinal control, which controls the vehicle's high-speed speed with three speeds with an equal difference of 20 km / h, and medium-speed speed with five speeds with an equal difference of 10 km / h. Steering control is single-lane or multi-lane lane change control.

4. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The high-speed driving scenario also includes sinusoidal continuous steering. The system acquires sinusoidal continuous steering condition information in the current high-speed driving scenario and outputs a seventh control signal. The seventh control signal includes longitudinal control, which controls the vehicle speed at three speeds with a difference of 20 km / h, and steering control, which inputs the steering wheel angle sinusoidally at a fixed frequency each time, and controls the steering wheel angle to achieve the maximum lateral acceleration.

5. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The variable speed driving scenarios include constant circle acceleration / deceleration and constant angle acceleration / deceleration. Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition information is a fixed circle acceleration and deceleration condition, then output the eighth control signal. The eighth control signal includes longitudinal control to control the vehicle to accelerate and decelerate at a certain acceleration, and steering control to control the vehicle to drive at a fixed radius. If the current scenario is a fixed-angle acceleration / deceleration condition, then the ninth control signal is output. The ninth control signal includes longitudinal control, which controls the vehicle to accelerate or decelerate at a certain acceleration, and steering control, which controls the steering wheel to drive at a fixed angle.

6. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The extreme driving scenarios include extreme conditions for cornering stability, extreme conditions for cornering rapid acceleration and deceleration, extreme conditions for straight-line emergency avoidance, extreme conditions for cornering rapid step jumps, and extreme conditions for slalom maneuvering. Obtain the scene condition information of the current variable speed driving scenario. If the current scene condition is the cornering stability limit condition or the cornering rapid acceleration and deceleration limit condition, output the tenth control signal. The tenth control signal includes longitudinal control to control the vehicle to enter the corner at an increased speed, or to increase the speed in the corner, and steering control to control the steering wheel angle according to the cornering path, and the speed increases until the vehicle reaches the stability limit. If the current scenario is a straight-line emergency avoidance limit or a cornering rapid step limit, then the eleventh control signal is output. The eleventh control signal includes longitudinal control to control the vehicle to drive at a constant speed and steering control to control the steering wheel angle with a step input until the vehicle reaches the stable limit. If the current scenario is a serpentine cone obstacle course, then the tenth control signal is output. The tenth control signal includes longitudinal control to control the vehicle to travel at a constant speed and steering control to control the steering wheel to pass through the cones at the maximum speed.

7. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The acquisition of vehicle status parameters through vehicle driving control includes: Step 1: Obtain steering wheel angle, steering wheel torque, left and right front wheel angles, rack displacement value, rack movement speed value, left and right rear wheel angles, and vehicle speed controlled by the rear steering controller rack. Step 2: Obtain the current scene conditions. If the current scene conditions are parking scenarios, then based on Step 1, obtain the center of gravity trajectory, the outer wheel ground contact imprint information, and the rear turn system noise value. Step 3: If the current scenario is a low-speed driving scenario, a medium-speed driving scenario, a high-speed driving scenario, a variable-speed driving scenario, or an extreme driving scenario, then based on Step 1, obtain the vehicle roll angle and the center of gravity slip angle. Step 4: If the current scenario is an abnormal scenario, then based on step 3, obtain the vehicle abnormal information and parameters.

8. The performance evaluation method for a vehicle rear-wheel active steering system according to claim 1, characterized in that, The final output performance index score includes: In the formula, Let X be the score of a certain evaluation indicator, and let X be the experimental value of the characteristic indicator. This represents the upper limit of the experimental value of the characteristic index. Lower limit of experimental values ​​for characteristic indicators; In the formula, This is the score for this experiment. … The score for a certain evaluation indicator. … This refers to the weighting coefficient corresponding to the score of a certain evaluation indicator.

9. A performance evaluation system for a vehicle's rear-wheel active steering system, characterized in that, This includes a scene definition module connected to the main control unit, a virtual scene and vehicle simulation module, a rear wheel steering system controller module, a rear wheel steering system actuator module, a test data analysis module, and an evaluation value calculation module. The scenario definition module is used to obtain the current functional scenario of the vehicle and obtain the scenario conditions of the current functional scenario based on the functional scenario. The virtual scene and vehicle simulation module is used to set the road conditions of the vehicle and the corresponding vehicle driving control according to the scene conditions. The vehicle driving control includes longitudinal control and steering control. The rear wheel steering system controller module is used to receive status signals from the vehicle simulation module and the rear wheel steering system actuator module, and output the calculated control commands to the rear wheel steering system actuator, while simultaneously feeding back the status signals of the rear wheel steering system to the vehicle simulation module. The rear wheel steering system actuator module is used to receive signals from the rear wheel steering system controller module and perform execution actions, while feeding back the status parameters of the rear wheel steering system actuator module to the rear wheel steering system controller module. The test data analysis module is used to acquire the state parameters of the vehicle and system through vehicle driving control, and determine the evaluation indicators based on the characteristic indicators of each state parameter and the scenario conditions. The evaluation indicators include several performance indicators, including maneuverability indicators, stability and safety indicators, handling indicators, vibration and noise indicators, and energy saving indicators. The evaluation value calculation module is used to obtain the dataset of evaluation indicators for vehicles without a rear-turn system and vehicles with a rear-turn system. Based on the dataset, it sets the upper and lower limits of the reference values ​​of the feature indicators, sets the weight coefficients for several performance indicators, calculates the weighted average value, and finally outputs the score value of the performance indicators. The main control device is used to execute the performance evaluation method of the rear-wheel active steering system of an automobile as described in any one of claims 1-8.

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