A k&c measurement method for a vehicle with rear wheel active steering system

Abstract

The application relates to a K&C measurement method for a vehicle with a rear-wheel active steering system, and relates to the technical field of rear-wheel steering, which comprises the following steps: setting multiple groups of test conditions; collecting test result information of a vehicle to be tested under the multiple groups of test conditions, wherein the test result information comprises rear-wheel steering angle information of rear wheels of the vehicle and motor action information of a steering motor; analyzing to obtain a steering overall strategy, wherein the steering overall strategy comprises a control strategy of a steering controller and steering related actions of the corresponding steering motor; formulating a K&C test strategy according to the steering overall strategy, and performing testing to obtain performance index information. The application can analyze the steering overall strategy of the system according to multiple tests performed in advance when the communication protocol of the rear-wheel active steering system is unknown, can provide a basis for subsequent formulation of a K&C test strategy based on the strategy, and can realize performance index testing of the vehicle with the rear-wheel active steering system and judge the influence of the rear-wheel active steering system on the vehicle performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rear wheel steering system, and particularly relates to a K&C measurement method for a vehicle with a rear wheel active steering system. BACKGROUND

[0002] Suspension K&C characteristics are the general term of suspension kinematics characteristics and suspension compliance characteristics, and the suspension K&C characteristics directly determine the handling and stability performance of the vehicle. The performance of the vehicle with the rear wheel steering system can be tested by the K&C test bench, and the corresponding vehicle performance parameters are obtained. The rear wheel steering system includes not only the rear wheel follow-up steering system, but also the rear wheel active steering system.

[0003] There are not many vehicles with rear wheel follow-up steering in the domestic market, but this technology has entered the sight of Chinese consumers with imported vehicles very early. Many imported vehicles are equipped with rear wheel follow-up steering systems, and the rear wheels are similar to the front wheels and have certain steering functions. The rear wheels can not only steer in the same direction as the front wheels, but also steer in the opposite direction.

[0004] The steering angle of the vehicle with the rear wheel active steering system can reach 10°. When the vehicle speed is below a certain speed, such as 40Km / h, the rear wheel active steering system can intelligently control the rear wheel to deflect in the opposite direction of the front wheel, which will shorten the turning diameter of the vehicle by more than 1m, and the minimum is only 11.6m, so that the vehicle can obtain more flexible maneuverability.

[0005] For civilian vehicles, slight understeering characteristics can ensure the stability of the vehicle in driving, but excessive steering often occurs when the vehicle turns at high speed. The rear wheel active steering system can compensate for the driving danger caused by excessive steering. At the same time, for medium and large vehicles and luxury vehicles, the rear wheel active steering can make the vehicle more flexible at low speed and more stable when turning at high speed, so that the driver can also have fun.

[0006] The rear wheel active steering system also has two cases of steering in the same direction as the front wheel and steering in the opposite direction of the front wheel, and the two cases will also show two completely different steering characteristics. Simply put, steering in the same direction increases understeering, and steering in the opposite direction increases oversteering. When the vehicle is driving at low speed, the opposite steering of the rear wheel and the front wheel can appropriately increase the oversteering. When the vehicle driving at high speed encounters an emergency lane change, without the help of any electronic auxiliary system, it is easy to have a tendency of oversteering. A small but important steering of the rear wheel in the same direction as the front wheel can compensate for the tendency of oversteering, so that the vehicle has better balance.

[0007] When the vehicle is turning, the change of the wheel contact area and wheel alignment will cause the change of the steering characteristics. It should be said that the rear wheel active steering technology can make up for the congenital defects of the vehicle steering mechanism caused by the use of rubber pneumatic tires. This rear wheel active steering is more like the working principle of the electronic stability program (ESP), that is, when the vehicle is moving at high speed, the stability of the vehicle driving posture is maintained by braking one or more wheels. For large luxury cars, the increasing wheelbase brings good comfortable space to the vehicle, but it also has a certain negative impact on the handling of the vehicle. Whether it is the turning radius at low speed or the stability at high speed will be discounted. By adding the rear wheel active steering system, the influence of the increase of the wheelbase on the driving characteristics of the vehicle can be compensated, and at the same time, a luxury car can also have good driving pleasure.

[0008] The principle of the rear wheel active steering system is also not complex, mainly including a steering controller and an action mechanism. The steering controller is used to receive the steering wheel angle information and the vehicle speed information sent by the vehicle controller, process the steering wheel angle information and the vehicle speed information according to the pre-set control strategy to obtain the rear wheel angle control information, and control the action mechanism to act according to the rear wheel angle control information. The action mechanism is generally a set of steering motor and screw nut mechanism, and the rear wheel angle control information can control the voltage and current change of the steering motor. The voltage and current change of the steering motor will cause the pull rod of the steering motor to change at a certain rate and amplitude. After the pull rod moves axially, it will drive the rear wheel to turn at a certain amplitude. On some vehicles, when the vehicle speed is above a certain speed, such as 60km / h, the rear wheel and the front wheel deflect in the same direction to improve the stability of high-speed turning. When the vehicle speed is below 60km / h, the rear wheel and the front wheel deflect in opposite directions to increase the flexibility of the vehicle. The technical core of the rear wheel active steering system is the control logic of the steering controller. Based on the control logic, various dynamic driving signals of the vehicle can be accepted, and then a suitable target steering angle is output after comprehensive judgment. In this process, any calculation error may cause the vehicle to lose control, especially when the vehicle is moving at high speed, which will increase the safety risk.

[0009] In order to test the influence of the rear wheel active steering system on the performance of the vehicle, the vehicle with the rear wheel active steering system needs to be placed on the K&C test bench for performance test, but how to obtain the control strategy of the rear wheel active steering system on the tested vehicle and how to set a reasonable test process after obtaining the strategy are the technical problems to be solved at present. SUMMARY

[0010] In view of the defects in the prior art, the purpose of the present application is to provide a K&C measurement method for a vehicle with a rear wheel active steering system, which can control the action of the rear wheel active steering system through multiple sets of test conditions, collect test result information, analyze the overall steering strategy of the rear wheel active steering system in combination with the test conditions and the test result information, and formulate a K&C test strategy based on the strategy to test the influence of the rear wheel active steering system on the performance indicators of the vehicle.

[0011] To achieve the above purpose, the technical solution adopted is:

[0012] The present application provides a K&C measurement method for a vehicle with a rear wheel active steering system, which includes a steering controller and a steering motor, comprising:

[0013] A plurality of sets of test conditions are set, each set of test conditions including vehicle speed and steering wheel angle;

[0014] The test result information of the vehicle to be tested under multiple sets of test conditions is collected, including rear wheel angle information of the rear wheels of the vehicle and motor action information of the steering motor;

[0015] According to the multiple sets of test conditions and the corresponding multiple sets of test result information, an overall steering strategy is analyzed, which includes the control strategy of the steering controller and the steering related action of the steering motor corresponding to the control strategy;

[0016] According to the overall steering strategy, a K&C test strategy is formulated, the vehicle to be tested is installed on a K&C test bench, and based on the K&C test strategy, the vehicle is tested and the performance indicators of the vehicle are collected; when the communication protocol file of the rear wheel active steering system is known, the steering controller is controlled based on the K&C test strategy during testing; when the communication protocol file of the rear wheel active steering system is unknown, the rear steering motor is controlled based on the K&C test strategy during testing.

[0017] In some embodiments, when the communication protocol file of the rear wheel active steering system is known, the collection of test result information of the vehicle to be tested under multiple sets of test conditions specifically includes the following steps:

[0018] The vehicle to be tested is installed on a K&C test bench, the background control system of the K&C test bench is connected with the steering controller through CAN tools based on the communication protocol file, and a rear wheel angle sensor is set on the vehicle to be tested;

[0019] The multiple sets of test conditions are sent to the steering controller through the background control system and the CAN tools, the steering controller controls the motor action of the steering motor according to the test conditions, and the rear wheels steer according to the motor action of the steering motor;

[0020] acquire the rear wheel turning angle information through the rear wheel turning angle sensor.

[0021] In some embodiments, when the communication protocol file of the rear wheel active steering system is known, the acquiring of the test result information of the vehicle to be tested under a plurality of test conditions comprises the following steps:

[0022] installing the vehicle to be tested on the K&C test bench, setting the mechanical arm of the K&C test bench on the side of the steering wheel of the vehicle to be tested, based on the communication protocol file, establishing communication connection between the background control system of the K&C test bench and the mechanical arm and the steering controller through the CAN tool, and setting the rear wheel turning angle sensor on the vehicle to be tested;

[0023] sending the plurality of test conditions to the mechanical arm and the background steering controller through the background control system and the CAN tool, the mechanical arm controlling the steering wheel to rotate according to the steering wheel turning angle, the controller controlling the motor action of the steering motor according to the test conditions, and the rear wheel steering according to the motor action of the steering motor;

[0024] acquiring the rear wheel turning angle information through the rear wheel turning angle sensor.

[0025] In some embodiments, the motor action information includes current information, voltage information, and pull rod action information of the steering motor.

[0026] In some embodiments, when the communication protocol file of the rear wheel active steering system is unknown, the acquiring of the test result information of the vehicle to be tested under a plurality of test conditions comprises the following steps:

[0027] installing current sensor, voltage sensor, and pull rod sensor on the vehicle to be tested;

[0028] making the vehicle to be tested drive on a preset road according to the plurality of test conditions, and acquiring vehicle speed, steering wheel turning angle, current information, voltage information, pull rod action information, and rear wheel turning angle information through the current sensor, voltage sensor, pull rod sensor, and rear wheel turning angle sensor respectively.

[0029] In some embodiments, the control strategy includes the steering angle and steering rate of the rear wheel under different steering wheel turning angle and vehicle speed intervals.

[0030] In some embodiments, the analysis of the overall steering strategy according to the plurality of test conditions and the corresponding plurality of test result information comprises the following steps:

[0031] drawing the rear wheel turning angle curve under each steering wheel turning angle and fitting it with the vehicle speed as the X-axis and the rear wheel turning angle as the Y-axis;

[0032] According to the fitted rear wheel turning angle curve analysis, the control strategy is obtained.

[0033] In some embodiments, the performance index information includes camber change rate, steering ratio, kingpin offset radius, kingpin trail, kingpin offset distance, left turning S° Ackerman error, left turning 0° Ackerman error, right turning S° Ackerman error, steering friction, and turning radius, and S is used to represent the rear wheel turning angle.

[0034] In some embodiments, when the communication protocol file of the rear wheel active steering system is known, the K&C test strategy is used to test the vehicle to be tested to collect the performance index information of the vehicle, and the K&C test strategy specifically includes the following steps:

[0035] The vehicle to be tested is installed on the K&C test bench, the background control system of the K&C test bench is connected with the steering controller through the CAN tool based on the communication protocol file, and the performance sensor is set on the vehicle to be tested;

[0036] The K&C test strategy is sent to the background steering controller through the background control system and the CAN tool;

[0037] The performance index information is collected through the performance sensor.

[0038] In some embodiments, when the communication protocol file of the rear wheel active steering system is unknown, the K&C test strategy is used to test the vehicle to be tested to collect the performance index information of the vehicle, and the K&C test strategy specifically includes the following steps:

[0039] The vehicle to be tested is installed on the K&C test bench, the background control system of the K&C test bench is connected with the steering motor, and the performance sensor is set on the vehicle to be tested;

[0040] The K&C test strategy is converted to obtain the current, voltage, and pull rod action corresponding to the strategy, and the current, voltage, and pull rod action are sent to the steering motor through the background control system to control the current, voltage, and pull rod action of the steering motor;

[0041] The performance information is collected through the performance sensor.

[0042] The technical scheme provided in the application has the following beneficial effects:

[0043] The technical scheme provided in the application has the following beneficial effects: The rear wheel active steering system does not depend on the steering overall strategy, and the steering overall strategy of any rear wheel active steering system can be obtained through pre-test. The K&C test strategy is formulated based on the strategy to test the performance index of the vehicle to be tested after the rear wheel active steering system is installed, so that the influence of any rear wheel active steering system on the performance index of the vehicle to be tested is obtained, and the rear wheel steering K&C measurement capability is formed.

[0044] Without relying on the communication protocol file of the rear-wheel active steering system in advance, the steering overall strategy of any rear-wheel active steering system can be obtained through pre-experiment, the steering motor is directly controlled based on the steering related action of the steering motor corresponding to the control strategy of the steering controller in the strategy during K&C test, so that the influence of any rear-wheel active steering system on the vehicle performance index of any vehicle to be tested is obtained, and the rear-wheel steering K&C measurement capability is formed. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 A flowchart of the K&C measurement method for the vehicle with the rear-wheel active steering system in the embodiment of the present application.

[0046] Figure 2 One of the flowcharts of step S2 when the communication protocol file of the rear-wheel active steering system is known in the embodiment of the present application.

[0047] Figure 3 The second flowchart of step S2 when the communication protocol file of the rear-wheel active steering system is known in the embodiment of the present application.

[0048] Figure 4 The flowchart of step S2 when the communication protocol file of the rear-wheel active steering system is unknown in the embodiment of the present application.

[0049] Figure 5 The flowchart of step S3 in the embodiment of the present application.

[0050] Figure 6 The schematic diagram of the rear-wheel steering angle curve when the steering wheel large angle is 90 degrees in the embodiment of the present application.

[0051] Figure 7 The flowchart of testing the vehicle to be tested based on the K&C test strategy when the communication protocol file of the rear-wheel active steering system is known in the embodiment of the present application. DETAILED DESCRIPTION

[0052] The present application will be further described in detail below in combination with the drawings and embodiments.

[0053] A rear wheel active steering system is installed on a vehicle to be tested, the rear wheel active steering system comprising a steering controller and a steering motor, the steering controller outputting corresponding control signals according to vehicle collected driving information, mainly vehicle speed and steering wheel angle, so as to control the steering motor and then control the rotation amplitude and steering rate of the rear wheel. In order to formulate a reasonable K&C test strategy to test the influence of the rear wheel active steering system on vehicle performance indicators, the steering overall strategy of the steering controller needs to be obtained first. However, the communication protocol file of the vehicle to be tested may or may not be known. If the communication protocol file is known, the tester can communicate with the steering controller and send test conditions to the steering controller. If the communication protocol file is unknown, the tester cannot communicate with the steering controller and cannot control the steering controller to respond by sending test conditions to the steering controller.

[0054] As shown in Figure 1 The embodiment of the present application provides a K&C measurement method for a vehicle with a rear wheel active steering system, a plurality of test conditions are set, each test condition comprising vehicle speed and steering wheel angle, test result information of the vehicle to be tested under the plurality of test conditions is collected, the test result information comprising rear wheel angle information of the rear wheel of the vehicle and motor action information of the steering motor, the steering overall strategy is analyzed according to the plurality of test conditions and the corresponding plurality of test result information, the steering overall strategy comprising the control strategy of the steering controller and the steering related action of the steering motor corresponding to the control strategy, the K&C test strategy is formulated according to the steering overall strategy, the vehicle to be tested is installed on a K&C test bench, and the vehicle performance indicator information is collected based on the K&C test strategy; when the communication protocol file of the rear wheel active steering system is known, the steering controller is controlled based on the K&C test strategy during testing; when the communication protocol file of the rear wheel active steering system is unknown, the rear steering motor is controlled based on the K&C test strategy during testing.

[0055] In the embodiment, all response actions of the rear wheel active steering system can be controlled through the plurality of test conditions, and the test result information is collected, the vehicle speed and the steering wheel angle are taken as inputs, and the rear wheel angle information is taken as output, the correlation between the inputs and the outputs is analyzed to obtain the control strategy of the steering controller, the output of each control strategy corresponds to the motor action information of the steering motor, that is, the steering controller outputs different control strategies under different vehicle speeds and steering wheel angles, the control strategy is controlled by the steering motor to control the motor action of itself, and different motor actions will result in different rear wheel angles. At the same time, the steering overall strategy of the rear wheel active steering system is obtained according to the control strategy of the steering controller and the steering related action of the steering motor corresponding to the control strategy.

[0056] The K&C test strategy is formulated based on the overall steering strategy, and the performance influence of the steering system on the vehicle is tested. When the communication protocol of the rear-wheel active steering system is unknown, the overall steering strategy of the system can be analyzed according to the multiple tests performed in advance, and the basis for subsequent K&C test strategy designation based on the strategy is provided, so as to realize the performance index test of the vehicle with the rear-wheel active steering system and judge the influence of the rear-wheel active steering system on the performance of the vehicle.

[0057] The test result information of the vehicle to be tested under multiple sets of test conditions is collected, and the communication protocol file of the rear-wheel active steering system is not relied on, so that the overall steering strategy of the rear-wheel active steering system installed on the vehicle to be tested of different enterprises can be obtained based on the present application, and the rear wheel driven by the rear-wheel active steering system installed on the vehicle to be tested of different enterprises can be controlled based on the K&C test strategy, so as to realize the performance index test of the vehicle with the rear-wheel active steering system and judge the influence of the rear-wheel active steering system on the performance of the vehicle.

[0058] In one specific embodiment, as shown in Figure 1 The K&C measurement method for the vehicle with the rear-wheel active steering system includes:

[0059] Step S1, multiple sets of test conditions are set, each set of test conditions including vehicle speed and steering wheel angle.

[0060] Step S2, test result information of the vehicle to be tested under multiple sets of test conditions is collected, the test result information including rear-wheel steering angle information of the rear wheel of the vehicle and motor action information of the steering motor.

[0061] Step S3, the overall steering strategy is analyzed according to the multiple sets of test conditions and the corresponding multiple sets of test result information, the overall steering strategy including the control strategy of the steering controller and the steering related action of the steering motor corresponding to the control strategy.

[0062] Step S4, the K&C test strategy is formulated based on the overall steering strategy, the vehicle to be tested is installed on the K&C test bench, and the performance index information of the vehicle is collected based on the K&C test strategy. When the communication protocol file of the rear-wheel active steering system is known, the steering controller is controlled based on the K&C test strategy during the test. When the communication protocol file of the rear-wheel active steering system is unknown, the rear steering motor is controlled based on the K&C test strategy during the test.

[0063] In the embodiment, without relying on the steering overall strategy of the rear wheel active steering system known in advance, the steering overall strategy of any rear wheel active steering system can be obtained through pre-test, the K&C test strategy is formulated based on the strategy to test the performance index influence of the vehicle after the rear wheel active steering system is installed, and thus the influence of any rear wheel active steering system on the vehicle performance index of any vehicle to be tested is obtained, and the rear wheel steering K&C measurement capability is formed.

[0064] Without relying on the communication protocol file of the rear wheel active steering system known in advance, the steering overall strategy of any rear wheel active steering system can be obtained through pre-test, the steering motor steering related action corresponding to the control strategy of the steering controller in the strategy is used to directly control the steering motor during the K&C test, and thus the influence of any rear wheel active steering system on the vehicle performance index of any vehicle to be tested is obtained, and the rear wheel steering K&C measurement capability is formed.

[0065] For the self-developed vehicle, the performance index can be improved, optimized, and checked, and for the competitive product vehicle, the rear wheel steering control logic, strategy, and performance can be investigated. The rear wheel steering K&C measurement capability can be formed, the customer's commissioned test business can be undertaken, and the industry test technology can be led.

[0066] In a preferred embodiment, as shown in Figure 2 When the communication protocol file of the rear wheel active steering system is known, step S2 specifically includes the following steps:

[0067] Step S21a, the vehicle to be tested is installed on the K&C test bench, the rear wheel steering controller is connected with the background control system of the K&C test bench through the CAN tool based on the communication protocol file, and the rear wheel steering angle sensor is arranged on the vehicle to be tested.

[0068] Step S22a, a plurality of test conditions are sent to the steering controller through the background control system and the CAN tool, the steering controller controls the motor action of the steering motor according to the test conditions, and the rear wheel is steered according to the motor action of the steering motor.

[0069] Step S23a, the rear wheel steering angle information is collected through the rear wheel steering angle sensor.

[0070] In the embodiment, the CAN tool is added to realize the bus communication with the steering controller (including analog sending and collecting bus signals). There are many kinds of CAN tools, including CANoe, CANalyzer, Vehicle spy, etc., which can all simulate sending and collecting bus signals. Of course, the premise is that whether the measured object is self-developed or a competitive product, the communication protocol file must be available.

[0071] When the communication protocol file of the K&C test bench is known, the background control system of the K&C test bench can establish a communication connection with the steering controller through the CAN tool, the background control system sends a plurality of test conditions to the steering controller, the steering controller respectively analyzes the required steering angle of the rear wheel and the steering related action required by the steering motor to realize the steering angle of the rear wheel based on the control strategy pre-stored in the steering controller according to each group of test conditions, and the rear wheel actively steers the rear wheel under the control of the rear wheel active steering system, and the rear wheel angle sensor collects the rear wheel angle information.

[0072] Subsequently, the control strategy of the steering controller can be analyzed according to the correspondence between the test conditions and the rear wheel angle information, and the steering related action of the steering motor corresponding to the control strategy can be further analyzed.

[0073] In a preferred embodiment, as shown in Figure 3 When the communication protocol file of the rear wheel active steering system is known, step S2 specifically includes the following steps:

[0074] Step S21b, install the vehicle to be tested on the K&C test bench, set the mechanical arm of the K&C test bench on the side of the steering wheel of the vehicle to be tested, establish a communication connection between the background control system of the K&C test bench and the mechanical arm and the steering controller through the CAN tool based on the communication protocol file, and set the rear wheel angle sensor on the vehicle to be tested.

[0075] Step S22b, send a plurality of test conditions to the mechanical arm and the background steering controller through the background control system and the CAN tool, the mechanical arm controls the steering wheel to rotate according to the steering wheel angle, the controller controls the motor action of the steering motor according to the test conditions, and the rear wheel steers according to the motor action of the steering motor.

[0076] Step S23b, collect the rear wheel angle information through the rear wheel angle sensor.

[0077] In this embodiment, during the pre-test, the steering wheel angle can be directly sent to the steering controller, or the steering wheel can be actually controlled to rotate by the mechanical arm, and the steering controller obtains the steering wheel angle from the mechanical arm or from the steering wheel.

[0078] In one specific embodiment, Table 1 is a test table when the communication protocol file is known:

[0079]

[0080]

[0081] Table 1 is a test table when the communication protocol file is known

[0082] In a preferred embodiment, the motor action information includes current information, voltage information of the steering motor, and pull rod action information.

[0083] In the embodiment, different rear wheel turning angles require different pull rod actions, and different pull rod actions require different steering motor currents and steering motor voltages to achieve.

[0084] In a preferred embodiment, as shown in Figure 4 When the communication protocol file of the rear wheel active steering system is unknown, step S2 specifically includes the following steps:

[0085] Step S21c, installing current sensors, voltage sensors, and pull rod sensors on the vehicle to be tested.

[0086] Step S22c, making the vehicle to be tested drive on a predetermined road according to a plurality of test conditions, and collecting vehicle speed, steering wheel turning angle, current information, voltage information, pull rod action information, and rear wheel turning angle information by using the current sensors, voltage sensors, pull rod sensors, and rear wheel turning angle sensors.

[0087] In the embodiment, the control strategy of the steering controller can be analyzed from different vehicle speeds, steering wheel turning angles, and rear wheel turning angle information, and the steering related actions of the steering motor corresponding to the control strategy can be obtained in combination with the current information, voltage information, and pull rod action information.

[0088] When the K&C test strategy is specified, compared with the case where the steering controller can be communicated based on the communication protocol file, in the case where communication is not possible, different vehicle speeds and steering wheel turning angles can be directly sent to the steering motor with different current information, voltage information, and pull rod action information, i.e., directly controlling the steering motor by bypassing the steering controller, and then collecting new vehicle performance index information.

[0089] In a specific embodiment, the K&C test strategy is formulated according to the overall steering strategy, which can be specifically that different rear wheel turning is caused by different vehicle speeds and steering wheel turning angles, and on this basis, test conditions containing different vehicle speeds and steering wheel turning angles are designed to obtain the influence of different rear wheel turning on the vehicle, which is the influence of the rear wheel active steering system on the vehicle.

[0090] Table 2 below is a test table when the communication protocol file is unknown and the steering wheel large angle turning is 90 degrees:

[0091]

[0092] Table 2 is a test table when the communication protocol file is unknown and the steering wheel large angle turning is 90 degrees, in a preferred embodiment, as shown in Figure 5 Step S3 specifically includes the following steps:

[0093] Step S31, draw the rear wheel steering angle curve under each steering wheel steering angle and perform fitting, with the vehicle speed as the X axis and the rear wheel steering angle as the Y axis.

[0094] Step S32, obtain the control strategy according to the fitted rear wheel steering angle curve.

[0095] In one specific embodiment, based on Table 1 above, only taking the steering wheel large angle steering angle of 90 degrees as an example, the rear wheel steering angle curve when the steering wheel large angle steering angle is 90 degrees is drawn, as shown in FIG. 4. Figure 6 At a vehicle speed of 0, the upper gray line is the rear wheel left steering curve in the rear wheel steering angle curve, and the lower black line is the rear wheel right steering curve in the rear wheel steering angle curve. Through the rear wheel steering angle curve, the steering angle range of the rear wheel steering can be intuitively known, and some rear wheel steering angle inflection point values, maximum values, minimum values, and steering rates in different vehicle speed intervals can be obtained.

[0096] In a preferred embodiment, the performance index information includes camber change rate, steering ratio, kingpin offset radius, kingpin trail, kingpin offset distance, left steering S° Ackermann error, left steering 0° Ackermann error, right steering S° Ackermann error, steering friction, and turning radius, and S is used to represent the rear wheel steering angle.

[0097] In a preferred embodiment, when the communication protocol file of the rear wheel active steering system is known, the vehicle to be tested is tested based on the K&C test strategy to collect the performance index information of the vehicle, as shown in Table 1. Figure 7 As shown, the method specifically includes the following steps:

[0098] Step S41a, install the vehicle to be tested on the K&C test bench, based on the communication protocol file, establish a communication connection between the background control system of the K&C test bench and the steering controller through the CAN tool, and set up performance sensors on the vehicle to be tested.

[0099] Step S42a, send the K&C test strategy based on the background control system and the CAN tool to the background steering controller.

[0100] Step S43a, collect the performance index information through the performance sensors.

[0101] In one specific embodiment, the vehicle to be tested is loaded onto the K&C test bench according to the traditional vehicle K&C measurement method, a mechanical arm is installed, and the mechanical arm can rotate the steering wheel. The vehicle to be tested is started, and the service brake is locked. The K&C test bench keeps the vertical position unchanged in the vertical direction and keeps all forces and moments zero in the horizontal direction.

[0102] The left and right steering wheel angle limits are found. The mechanical arm torque limit is set to 15 N.m. When the mechanical arm starts to turn to the left (or right) from the steering wheel middle position (i.e. zero position), when the mechanical arm torque limit reaches the set value of 15 N.m, it is considered that the wheel angle has reached the left (or right) limit position. When the mechanical arm torque limit reaches the set value of 15 N.m, it will immediately start to turn in the opposite direction. When the mechanical arm torque limit reaches the set value of 15 N.m, it is considered that the wheel angle has reached the right (or left) limit position. The wheel platform angle at the two positions when the mechanical arm torque limit reaches the set value of 15 N.m is the maximum wheel angle. At this time, the steering robot angle is the maximum steering wheel angle L in the corresponding steering direction.

[0103] For the rear wheel steering angle controlled by the CAN tool, the rear control system connected to the CAN tool inputs the vehicle speed, steering wheel angle, and time to test the performance index information of the vehicle. During testing, multiple working conditions can be tested.

[0104] Test condition one: steering working condition under the condition that the vehicle body is stationary: test data at a small steering wheel angle of 3 degrees.

[0105] The steering motor turns the steering wheel to the set value S from the middle position and returns. The steering wheel is placed in the middle position, and the steering wheel is turned to the left (or right) from the zero position to the set value S, and then the steering wheel is turned in the opposite direction to the set value S, and then returned to the zero position, completing one test process. The control wheel platform return torque (torque around the Z direction) is zero during the test process to ensure that the tire is free to rotate, and the steering wheel speed is V. One test process is repeated three times. The first time is a warm-up cycle (no data is stored), and the second and third times are test cycles (data is stored). (Steering wheel angle S < maximum steering wheel angle L).

[0106] First, perform the steering working condition under the condition that the vehicle body is stationary, i.e. the bench is not tilted.

[0107] Then perform the steering working condition under the condition that the vehicle body is tilted, i.e. the bench is tilted, with a tilt range of -2° to 2°.

[0108] Test condition two: steering working condition under the condition that the vehicle body is moderately tilted: test data at a moderate steering wheel angle of 45 degrees.

[0109] The steering motor rotates the steering wheel from the neutral position to the set value S, and then returns. The steering wheel is placed in the neutral position, and the steering wheel is rotated to the set value S from the zero position to the left (or right), and then the steering wheel is rotated to the set value S in the opposite direction, and then returns to the zero position to complete a test process. The return torque (torque around the Z direction) of the platform of the vehicle wheel is controlled to be zero during the test process to ensure that the tire is freely rotating, and the steering wheel speed is V. The test process is repeated three times. The first time is a warm-up cycle (without data storage), and the second and third times are test cycles (with data storage). (The steering wheel angle S < the maximum steering wheel angle L).

[0110] First, the steering condition of the stationary vehicle body, i.e., the steering condition of the bench without tilting, is performed.

[0111] Then, the steering condition of the vehicle body tilting, i.e., the steering condition of the bench tilting, is performed, and the tilting range is -3°-3°.

[0112] Test condition three, steering condition under the extreme tilting state of the vehicle body: data at a large steering wheel angle of 90 degrees is tested.

[0113] The steering motor rotates the steering wheel from the neutral position to the set value S, and then returns. The steering wheel is placed in the neutral position, and the steering wheel is rotated to the set value S from the zero position to the left (or right), and then the steering wheel is rotated to the set value S in the opposite direction, and then returns to the zero position to complete a test process. The return torque (torque around the Z direction) of the platform of the vehicle wheel is controlled to be zero during the test process to ensure that the tire is freely rotating, and the steering wheel speed is V. The test process is repeated three times. The first time is a warm-up cycle (without data storage), and the second and third times are test cycles (with data storage). (The steering wheel angle S < the maximum steering wheel angle L).

[0114] First, the steering condition of the stationary vehicle body, i.e., the steering condition of the bench without tilting, is performed.

[0115] Then, the steering condition of the vehicle body tilting, i.e., the steering condition of the bench tilting, is performed, and the tilting range is -5°-5°.

[0116] In a preferred embodiment, when the communication protocol file of the rear wheel active steering system is unknown, the vehicle to be tested is tested based on the K&C test strategy to collect performance index information of the vehicle, specifically including the following steps:

[0117] Step S41b, installing the vehicle to be tested on the K&C test bench, establishing a communication connection between the background control system of the K&C test bench and the steering motor, and setting a performance sensor on the vehicle to be tested.

[0118] Step S42b, converting the K&C test strategy to obtain the current, voltage, and pull rod action corresponding to the strategy, and sending them to the steering motor through the background control system to control the current, voltage, and pull rod action of the steering motor.

[0119] Step S43b, collecting performance information by performance sensor.

[0120] In one specific embodiment, the vehicle to be tested is loaded onto a K&C test bench in a conventional vehicle K&C measurement method, a mechanical arm is installed, and the mechanical arm can turn the steering wheel. The vehicle to be tested is started, and the service brake is locked. The K&C test bench keeps the vertical position unchanged in the vertical direction and keeps all forces and moments zero in the horizontal direction.

[0121] The left and right steering wheel angle limits are found. The mechanical arm torque limit is set to 15 N·m, and when the mechanical arm torque limit reaches the set value of 15 N·m when the mechanical arm starts to turn left (or right) from the middle position (i.e., zero position) of the steering wheel, it is considered that the wheel angle has reached the left (or right) limit position. When the mechanical arm torque limit reaches the set value of 15 N·m, it will immediately start to turn in the opposite direction, and when the mechanical arm torque limit reaches the set value of 15 N·m, it is considered that the wheel angle has reached the right (or left) limit position. The wheel platform angle at the two positions when the mechanical arm torque limit reaches the set value of 15 N·m is the maximum wheel angle, and at this time, the steering robot's angle is the maximum steering wheel angle L corresponding to the steering wheel.

[0122] For rear wheel steering angles that cannot be controlled by CAN tools: use the rear wheel steering motor voltage, current, current time, and steering link displacement obtained by the foregoing steps to control the steering motor, output corresponding voltage, current, and current time to the rear wheel steering motor to complete rear wheel steering, and test the performance index information of the vehicle. The specific test can be performed under multiple working conditions.

[0123] Test condition one: steering working condition under vehicle body static state: take the data at a small steering angle of 3 degrees for testing.

[0124] Steering motor turns the steering wheel from the middle position to the set value S and returns. Place the steering wheel in the middle position, turn the steering wheel to the left (or right) from zero to the set value S, then turn the steering wheel to the set value S in the opposite direction, and return to zero to complete one test process. Control the wheel platform return torque (torque around the Z direction) to zero during the test process to ensure that the tire is free to rotate, and the steering wheel speed is V. Repeat the test process three times. The first time is a warm-up cycle (no data is stored), and the second and third times are test cycles (data is stored). (Steering wheel angle S < maximum steering wheel angle L).

[0125] First, perform the steering working condition under the vehicle body static, i.e., the test bench does not roll.

[0126] Then, perform the steering working condition under the vehicle body roll, i.e., the test bench rolls, and the roll range is -2° ~ 2°.

[0127] Test condition two, steering condition under the state of medium body roll: take the data under the medium angle of steering wheel 45 degrees to test.

[0128] Steering motor rotates the steering wheel from the middle position to the set value S, and returns. The steering wheel is placed in the middle position, and the steering wheel is rotated to the set value S from zero position to the left (or right), and then the steering wheel is rotated to the set value S in the opposite direction, and returns to zero position, to complete a test process. The return torque (torque around Z direction) of the platform of the wheel is controlled to be zero during the test process, to ensure that the tire is free to rotate, and the steering wheel speed is V, and one test process is repeated three times. The first time is a warm-up cycle (without storing data), and the second and third times are test cycle times (storing data). (Steering wheel angle S < maximum steering wheel angle L).

[0129] First, the steering condition under the state of body static, i.e. the chassis without roll, is executed.

[0130] Then, the steering condition under the state of body roll, i.e. the chassis with roll, is executed, and the roll range is -3° ~ 3°.

[0131] Test condition three, steering condition under the state of limit body roll: take the data under the large angle of steering wheel 90 degrees to test.

[0132] Steering motor rotates the steering wheel from the middle position to the set value S, and returns. The steering wheel is placed in the middle position, and the steering wheel is rotated to the set value S from zero position to the left (or right), and then the steering wheel is rotated to the set value S in the opposite direction, and returns to zero position, to complete a test process. The return torque (torque around Z direction) of the platform of the wheel is controlled to be zero during the test process, to ensure that the tire is free to rotate, and the steering wheel speed is V, and one test process is repeated three times. The first time is a warm-up cycle (without storing data), and the second and third times are test cycle times (storing data). (Steering wheel angle S < maximum steering wheel angle L).

[0133] First, the steering condition under the state of body static, i.e. the chassis without roll, is executed.

[0134] Then, the steering condition under the state of body roll, i.e. the chassis with roll, is executed, and the roll range is -5° ~ 5°.

[0135] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for K&C measurement for a vehicle with a rear wheel active steering system, the rear wheel active steering system comprising a steering controller and a steering motor; characterized in that, The application relates to a method for testing a rear-wheel active steering system of a vehicle, which comprises the following steps: setting multiple groups of test conditions, each of which comprises a vehicle speed and a steering wheel steering angle; collecting test result information of the vehicle under the multiple groups of test conditions, wherein the test result information comprises rear-wheel steering angle information and motor action information of a steering motor; analyzing the multiple groups of test conditions and the corresponding multiple groups of test result information to obtain a steering overall strategy, wherein the steering overall strategy comprises a control strategy of a steering controller and steering related action of the steering motor corresponding to the control strategy; formulating a K&C test strategy according to the steering overall strategy, installing the vehicle to be tested on a K&C test bench, testing the vehicle based on the K&C test strategy, and collecting performance index information of the vehicle; when a communication protocol file of the rear-wheel active steering system is known, the steering controller is controlled based on the K&C test strategy during the testing; when the communication protocol file of the rear-wheel active steering system is unknown, the rear steering motor is controlled based on the K&C test strategy during the testing.

2. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, When the communication protocol file of the rear-wheel active steering system is known, the collecting of the test result information of the vehicle under the multiple groups of test conditions comprises the following steps: installing the vehicle to be tested on the K&C test bench, establishing a communication connection between a background control system of the K&C test bench and the steering controller through a CAN tool based on the communication protocol file, and setting a rear-wheel steering angle sensor on the vehicle to be tested; sending the multiple groups of test conditions to the steering controller through the background control system and the CAN tool, controlling motor action of the steering motor according to the test conditions, and steering the rear wheel according to the motor action of the steering motor; collecting the rear-wheel steering angle information through the rear-wheel steering angle sensor.

3. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, When the communication protocol file of the rear-wheel active steering system is known, the collecting of the test result information of the vehicle under the multiple groups of test conditions comprises the following steps: installing the vehicle to be tested on the K&C test bench, setting a mechanical arm of the K&C test bench on a side of a steering wheel of the vehicle to be tested, establishing a communication connection between a background control system of the K&C test bench and the mechanical arm and the steering controller through a CAN tool based on the communication protocol file, and setting a rear-wheel steering angle sensor on the vehicle to be tested; sending the multiple groups of test conditions to the mechanical arm and the background steering controller through the background control system and the CAN tool, controlling the steering wheel to rotate according to the steering wheel steering angle, controlling motor action of the steering motor according to the test conditions, and steering the rear wheel according to the motor action of the steering motor; collecting the rear-wheel steering angle information through the rear-wheel steering angle sensor.

4. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, The motor action information comprises current information, voltage information and pull rod action information of the steering motor.

5. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 4, wherein, When the communication protocol file of the rear-wheel active steering system is unknown, the collecting of the test result information of the vehicle under the multiple groups of test conditions comprises the following steps: installing a current sensor, a voltage sensor and a pull rod sensor on the vehicle to be tested; The vehicle to be tested drives on a preset road according to the multiple sets of test conditions, and the current sensor, the voltage sensor, the pull rod sensor, and the rear wheel rotation angle sensor are used to collect the vehicle speed, the steering wheel rotation angle, the current information, the voltage information, the pull rod action information, and the rear wheel rotation angle information, respectively.

6. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, The control strategy includes the steering angle and the steering rate of the rear wheel under different steering wheel rotation angles and vehicle speed intervals.

7. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 6, wherein, The steering overall strategy is obtained by analyzing the multiple sets of test conditions and the corresponding multiple sets of test result information, and specifically includes the following steps: The rear wheel rotation angle curve under each steering wheel rotation angle is drawn and fitted with the vehicle speed as the X-axis and the rear wheel rotation angle as the Y-axis. The control strategy is obtained by analyzing the fitted rear wheel rotation angle curve.

8. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, The performance index information includes the camber change rate, the steering speed ratio, the kingpin offset radius, the kingpin drag distance, the kingpin offset distance, the left turning S° Ackermann error, the left turning 0° Ackermann error, the right turning S° Ackermann error, the steering friction, and the turning radius, and S is used to represent the rear wheel steering angle.

9. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 1, wherein, When the communication protocol file of the rear wheel active steering system is known, the vehicle to be tested is tested based on the K&C test strategy to collect the performance index information of the vehicle, and specifically includes the following steps: The vehicle to be tested is installed on the K&C test bench, the background control system of the K&C test bench and the steering controller are communicatively connected through the CAN tool based on the communication protocol file, and the performance sensor is set on the vehicle to be tested; The K&C test strategy is sent to the background steering controller through the background control system and the CAN tool; The performance index information is collected through the performance sensor.

10. The method for K&C measurement for a vehicle with a rear wheel active steering system according to claim 5, wherein, When the communication protocol file of the rear wheel active steering system is unknown, the vehicle to be tested is tested based on the K&C test strategy to collect the performance index information of the vehicle, and specifically includes the following steps: The vehicle to be tested is installed on the K&C test bench, the background control system of the K&C test bench and the steering motor are communicatively connected, and the performance sensor is set on the vehicle to be tested; The K&C test strategy is converted to obtain the current, voltage, and pull rod action corresponding to the strategy, and is sent to the steering motor through the background control system to control the current, voltage, and pull rod action of the steering motor; The performance information is collected through the performance sensor.

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