Brake test bench for simulating wheel slippage and control method thereof

Abstract

The invention relates to a brake test bench for simulating wheel slippage and a control method thereof. A dragging motor, a clutch, a vehicle body inertia simulation module, a slippage simulation device, a wheel inertia simulation module and a brake actuator are sequentially and coaxially arranged; the rack controller is in communication connection with the dragging motor, the clutch, the vehicle body inertia simulation module, the slip simulation device, the wheel inertia simulation module and the brake actuator. The vehicle body inertia simulation module and the wheel inertia simulation module transmit collected data to the rack controller, and the rack controller controls the motion of the slip simulation device by adopting a multi-closed control strategy according to the data. The vehicle body inertia simulation module, the slippage simulation device and the wheel inertia simulation module are arranged, the action of the slippage simulation device is controlled through data of the vehicle body inertia simulation module and the wheel inertia simulation module, needed slippage occurs, a multi-closed control strategy is adopted for control, and slippage change control is more accurate.

Description

Technical Field

[0001] This invention relates to a brake test bench for simulating wheel slippage, and more particularly to a brake test bench for simulating wheel slippage and its control method. Background Technology

[0002] Currently, braking function testing on the market generally employs two methods: bench testing and real-vehicle testing. In China, due to safety regulations and limitations of testing facilities, new braking systems, such as EMB, often face difficulties in completing real-vehicle testing under high-speed and varied road conditions during their initial development stages, primarily for safety reasons. Furthermore, commercially available benches typically use roller mechanisms to simulate road surfaces. These mechanisms not only struggle to simulate high speeds and alternating road conditions but also offer relatively limited testing functionality. Therefore, there is a lack of functional testing platforms suitable for simulating high-speed and alternating road conditions.

[0003] Chinese patent application CN120445679A discloses an electric inertia simulation braking power test bench and its electric inertia control method, relating to the field of electric drive simulation technology for flywheels. The test bench includes a motor, an incremental encoder, a main shaft, a flywheel, a lever arm frame, a mechanical friction braking torque sensor, an electric drive control system, and a brake disc. The motor has an incremental encoder mounted at its rear end, and its transmission end is connected to the main shaft via a coupling. The flywheel is mounted on the main shaft, and a brake disc is mounted on the lever arm frame, which is also connected to the mechanical friction braking torque sensor. This invention synchronously collects angular velocity, angular displacement, and mechanical friction braking torque, calculates and assigns the motor torque, allowing the test bench to operate in a state approaching an equivalent flywheel and essentially without system resistance. However, this patent cannot change the wheel slip ratio.

[0004] Therefore, providing a test bench that can change the slip ratio is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing a braking test bench for simulating wheel slippage and its control method.

[0006] The objective of this invention can be achieved through the following technical solutions: According to one aspect of the present invention, a braking test bench for simulating wheel slippage is provided, comprising a bench controller, a drive motor, a clutch, a vehicle body inertia simulation module, a slippage simulation device, a wheel inertia simulation module, and a brake actuator, wherein the drive motor, clutch, vehicle body inertia simulation module, slippage simulation device, wheel inertia simulation module, and brake actuator are arranged coaxially in sequence, and the bench controller is communicatively connected to the drive motor, clutch, vehicle body inertia simulation module, slippage simulation device, wheel inertia simulation module, and brake actuator respectively; The vehicle body inertia simulation module and the wheel inertia simulation module transmit the collected data to the bench controller, which then uses a multi-closed control strategy to control the movement of the slip simulation device based on the data.

[0007] As a preferred technical solution, the skid simulation device includes a skid control unit and a power transmission unit. The skid control unit is communicatively connected to the bench controller, and the skid control unit is movably connected to the power transmission unit. The power transmission unit is coaxially arranged with the vehicle body inertia simulation module and the wheel inertia simulation module.

[0008] As a preferred technical solution, the test bench includes a first shaft and a second shaft, the power transmission unit is connected to the first shaft and the second shaft respectively, the first shaft and the second shaft are coaxial, the drive motor, the clutch and the vehicle body inertia simulation module are sequentially installed on the first shaft, and the wheel inertia simulation module and the brake actuator are sequentially installed on the second shaft.

[0009] As a preferred technical solution, the power transmission unit includes a friction disc, a pressure disc, a diaphragm spring, a clamping spring, and a release bearing. The first shaft is connected to the friction disc, and the release bearing is connected to the pressure disc through the diaphragm spring and the clamping spring. The pressure disc and the friction disc may or may not be in contact. The release bearing is mounted on a second shaft, which passes through the pressure disc, the diaphragm spring, the clamping spring, and the release bearing.

[0010] As a preferred technical solution, the sliding control unit includes a servo motor, a gear pair, a nut, a screw, and a pressure rod. The gear pair is connected to the servo motor and the nut respectively. The nut is mounted on the screw and engages with the screw for transmission. The pressure rod is connected to the screw and the release bearing respectively.

[0011] According to another aspect of the present invention, a slip control method based on a braking test bench for simulating wheel slip as described above is provided, the method comprising: S1. The bench controller disengages the clutch after the drive motor reaches a preset speed, and at the same time, the brake actuator clamps the sliding simulation device. S2. The bench controller calculates the vehicle friction torque T_wheel based on the data from the vehicle body inertia simulation module and the wheel inertia simulation module. S3. The vehicle friction torque T_wheel is used as the input signal of the multi-closed-loop control strategy, and the action of the slip simulation device is controlled by combining the input signal and the feedback signal of the slip simulation device.

[0012] As a preferred technical solution, the multi-closed-loop control strategy includes friction torque control, which includes a feedforward unit and a feedback unit. The vehicle friction torque T_wheel is input to the feedforward unit, and the vehicle friction torque T_wheel and the feedback signal from the slip simulation device are input to the feedback unit. The output signals of the feedforward unit and the feedback unit jointly adjust the target opening s_des.

[0013] As a preferred technical solution, the multi-closed-loop control strategy further includes motor position control, which adjusts the motor position and obtains the target speed v_des based on the target opening degree s_des and the feedback signal from the slip simulation device.

[0014] As a preferred technical solution, the multi-closed-loop control strategy also includes speed control, which adjusts the motor speed according to the target speed v_des and the feedback signal from the slip simulation device to obtain the target current I_des.

[0015] As a preferred technical solution, the multi-closed-loop control strategy further includes current control, adjusting the motor current according to the target current I_des and the feedback signal of the slip simulation device to obtain the target voltage u_des, and adjusting the action of the slip simulation device according to the target voltage.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention includes a vehicle body inertia simulation module, a slippage simulation device, and a wheel inertia simulation module. The slippage simulation device is controlled by data from the vehicle body inertia simulation module and the wheel inertia simulation module to produce the required slippage. A multi-closed control strategy is used for control, resulting in more precise control of slippage changes.

[0017] 2. This invention precisely controls the movement distance of the screw through the cooperation of a servo motor, gear pair, nut, screw, and pressure rod, thereby dynamically controlling the contact between the pressure plate and the friction plate, and thus achieving sliding control.

[0018] 3. This invention adopts a multi-closed-loop control strategy, which combines the input signal and the feedback signal of the sliding simulation device to jointly control the action of the sliding simulation device, avoiding local failures caused by single control, and greatly improving the overall reliability and adaptability to operating conditions. At the same time, feedback signals are received in each closed loop for adjustment to ensure the accuracy of control. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the sliding simulation device of the present invention; Figure 3 This is a schematic diagram of the operation of the sliding simulation device of the present invention; Figure 4 This is a schematic diagram illustrating the execution process of the present invention; Figure 5 This is a schematic diagram of the signal transmission process of the present invention; 1. Bench controller; 2. Drive motor; 3. Vehicle body inertia simulation module; 4. Vehicle body speed sensor; 5. Slip simulation device; 6. Wheel inertia simulation module; 7. Wheel speed sensor; 8. Wheel torque sensor; 9. Brake actuator; 10. First shaft; 11. Second shaft; 12. Clutch; 51. Servo motor; 52. Gear pair; 53. Nut; 54. Screw; 55. Pressure rod; 56. Friction disc; 57. Pressure plate; 58. Diaphragm spring; 59. Compression spring; 60. Release bearing. Detailed Implementation

[0020] 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, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] Example 1 like Figures 1-3 As shown, a braking test bench for simulating wheel slippage includes a bench controller 1, a drive motor 2, a clutch 12, a vehicle body inertia simulation module 3, a slippage simulation device 5, a wheel inertia simulation module 6, and a brake actuator 9. The drive motor 2, clutch 12, vehicle body inertia simulation module 3, slippage simulation device 5, wheel inertia simulation module 6, and brake actuator 9 are arranged coaxially in sequence. The bench controller 1 is communicatively connected to the drive motor 2, clutch 12, vehicle body inertia simulation module 3, slippage simulation device 5, wheel inertia simulation module 6, and brake actuator 9. The vehicle body inertia simulation module 3 and the wheel inertia simulation module 6 transmit the collected data to the bench controller 1. The bench controller 1 uses a multi-closed control strategy to control the action of the slip simulation device 5 based on the data.

[0022] In this embodiment, the vehicle body inertia simulation module 3 and the wheel inertia simulation module 6 of the test bench are arranged coaxially and separated by a slip simulation device 5 to simulate tire slippage during braking. The upper-level control strategy sends control commands to the servo motor 51 on the slip simulation device 5. The servo motor 51 drives the ball screw to push the pressure rod 55 of the slip simulation device 5, so that the braking torque of the brake actuator 9 on the right side of the slip simulation device 5 is no longer transmitted to the vehicle body inertia simulation module 3 on the left side. The rotation speeds of the left and right axes of the slip simulation device 5 are no longer the same, thus simulating the tire slippage effect.

[0023] The brake actuator 9 can be a hub motor or an EMB actuator, or a combination of a hub motor and an EMB actuator as the brake actuator 9; the test bench can be adapted to different brake actuators according to specific circumstances.

[0024] Compared to the commonly used roller testing mechanisms on the market, the contact between the wheel and the roller becomes very unstable and unsafe at high vehicle speeds, resulting in a poor testing environment. Therefore, the advantages of the coaxial arrangement of the inertia modules in this invention are: the transmission of braking force and simulated vehicle speed of the motor is smoother and less prone to deviation during functional testing; at the same time, when conducting different types of functional tests, such as braking performance and anti-lock braking control tests, the drive performance can be tested using this coaxial structure without disassembling other hardware components, simply by reversing the hub motor and disconnecting the drive motor. This coaxial structure is stable and practical.

[0025] When an external hub motor is connected, a certain initial speed can be simulated by controlling the drive motor 2 to test the energy recovery when the hub motor generates regenerative braking. Alternatively, the connection of the drive motor 2 can be disconnected, the slip simulation device 5 can be closed to allow the torque to be transmitted normally, and the hub motor can be rotated forward to test the driving performance. When both the hub motor and EMB actuator are connected to the external system, the wheel status signal measured by the torque and speed sensor is sent to the upper controller. The controller can also perform compound braking torque distribution based on the current braking intensity and send control signals to the motor and actuator to optimize and verify the compound braking strategy. Depending on the vehicle's load, the clutch 3 and slip simulation device 5 can be kept closed, and the maximum braking torque can be applied until the wheels lock up to test the braking performance of the test bench; the change in braking force under brake temperature can also be observed to test the thermal stability of the test bench; and the change in slip ratio under various working conditions can also be simulated to test the anti-lock braking control function of the test bench.

[0026] The vehicle body inertia simulation module includes a vehicle body speed sensor 4 and a vehicle body torque sensor, which are mounted on the first shaft 10; the wheel inertia simulation module 6 includes a wheel speed sensor 7 and a wheel torque sensor 8, which are mounted on the second shaft 11.

[0027] The skid simulation device 5 includes a skid control unit and a power transmission unit. The skid control unit is communicatively connected to the bench controller 1, and the skid control unit is movably connected to the power transmission unit. The power transmission unit is coaxially arranged with the vehicle body inertia simulation module 3 and the wheel inertia simulation module 6.

[0028] The test bench includes a first shaft 10 and a second shaft 11. The power transmission unit is connected to the first shaft 10 and the second shaft 11 respectively. The first shaft 10 and the second shaft 11 are coaxial. The drive motor 2, the clutch 12 and the vehicle body inertia simulation module 3 are sequentially installed on the first shaft 10. The wheel inertia simulation module 6 and the brake actuator 9 are sequentially installed on the second shaft 11.

[0029] The power transmission unit includes a friction disc 56, a pressure disc 57, a diaphragm spring 58, a clamping spring 59, and a release bearing 60. The first shaft 10 is connected to the friction disc 56. The release bearing 60 is connected to the pressure disc 57 via the diaphragm spring 58 and the clamping spring 59. The pressure disc 57 and the friction disc 56 may or may not be in contact. The release bearing 60 is mounted on a second shaft 11, which passes through the pressure disc 57, the diaphragm spring 58, the clamping spring 59, and the release bearing 60.

[0030] The sliding control unit includes a servo motor 51, a gear pair 52, a nut 53, a screw 54, and a pressure rod 55. The gear pair 52 is connected to the servo motor 51 and the nut 53 respectively. The nut 53 is mounted on the screw 54 and cooperates with the screw 54 for transmission. The pressure rod 55 is connected to the screw 54 and the release bearing 60 respectively.

[0031] In this embodiment, the working process of the sliding simulation device 5 is as follows: the bench controller 1 controls the servo motor 51 to rotate, thereby causing the gear pair 52 to rotate. The gear pair 52 is divided into a driving gear and a driven gear. The driving gear is connected to the servo motor 51, and the driven gear meshes with the driving gear. The nut 53 is set at the center of the driven gear. When the driven gear rotates, the nut 53 rotates together, which in turn causes the screw 54 to rotate. The screw 54 can be a ball screw. The pressure rod 55 can rotate around a fixed point. As the screw 54 extends or retracts, the pressure rod 55 is offset based on the lever principle. The release bearing 60 moves in the axial direction of the first shaft 10 or the second shaft 11. The release bearing 60 compresses the diaphragm spring 58 and the clamping spring 59 to bring the pressure plate 57 closer to the friction plate 56.

[0032] Example 2 like Figure 4 and Figure 5 As shown, a slip control method based on a braking test bench for simulating wheel slippage is disclosed, the method comprising: S1. After the bench controller 1 causes the drive motor 2 to reach the preset speed, it disengages the clutch 12 and simultaneously causes the brake actuator 9 to clamp the sliding simulation device 5. S2. The bench controller 1 calculates the vehicle friction torque T_wheel based on the data from the vehicle body inertia simulation module 3 and the wheel inertia simulation module 6. S3. The vehicle friction torque T_wheel is used as the input signal of the multi-closed-loop control strategy, and the action of the slip simulation device 5 is controlled by combining the input signal and the feedback signal of the slip simulation device 5.

[0033] The multi-closed-loop control strategy includes friction torque control, which includes a feedforward unit and a feedback unit. The vehicle friction torque T_wheel is input to the feedforward unit, and the vehicle friction torque T_wheel and the feedback signal of the slip simulation device 5 are input to the feedback unit. The output signals of the feedforward unit and the feedback unit jointly adjust the target opening s_des.

[0034] The multi-closed-loop control strategy also includes motor position control, which adjusts the motor position and obtains the target speed v_des based on the target opening s_des and the feedback signal from the slip simulation device 5.

[0035] The multi-closed-loop control strategy also includes speed control, which adjusts the motor speed and obtains the target current I_des based on the target speed v_des and the feedback signal from the slip simulation device 5.

[0036] The multi-closed-loop control strategy also includes current control, which adjusts the motor current and obtains the target voltage u_des based on the target current I_des and the feedback signal of the slip simulation device 5, and adjusts the operation of the slip simulation device 5 based on the target voltage.

[0037] In this embodiment, when formulating the control algorithm, closed-loop compensation needs to be performed based on the current test bench state. Since the working principle of this test bench is similar to the clamping force control of EMB, the pressure of the sliding simulator 5 is controlled by the motor screw, thereby changing the test bench friction torque T1. Therefore, a multi-closed-loop control strategy can be built, namely, a friction torque control loop, a motor position control loop, a speed control loop, and a current control loop. The vehicle friction torque T_wheel needs to be calculated first, and then used as the signal input for the multi-closed-loop control strategy.

[0038] The calculation process for the vehicle friction torque T_wheel is as follows: Taking the braking mode workflow as an example, during EMB performance testing, the speed command set for the drive motor 2, after calibration, serves as the initial vehicle speed of the test bench. Simultaneously, a custom initial speed v0 is defined in the vehicle simulation environment. Since the test bench environment is a high-speed environment, the initial speed v0 is generally set to >120 km / h. Upon reaching the specified speed, the jaw clutch 12 connected to the drive motor 2 is disconnected, and the EMB prototype sends a pre-set clamping force signal to the brake actuator 9 via dspace control.

[0039] At this point, the vehicle body inertia simulation module 3 and the wheel inertia simulation module 6 respectively read out the rotational speed and torque signals of the two parts. The vehicle body inertia simulation module 3 reads out the vehicle body speed w1 and the test bench friction torque T1, and the wheel inertia simulation module 6 reads out the wheel speed w2 and the braking torque T2. Among them, the vehicle body speed w1 can simulate the vehicle speed, and the wheel speed w2 simulates the wheel speed. When the slip simulator 5 generates friction, the test bench friction torque T1 simulates the friction torque transmitted between the vehicle and the road, and the braking torque T2 simulates the braking torque of the brake on the brake disc. The test bench slip ratio x1 is obtained from the vehicle body speed w1 and the wheel speed w2. According to the experimental measurement, the test bench friction characteristic curve is obtained, and the graph T1-s of the variation of the test bench friction torque T1 with the opening of the clutch 12 is obtained, where s is the opening of the clutch 12.

[0040] Establish a conventional vehicle dynamics model, which adopts an existing model. The braking torque T2 is input into the vehicle dynamics model. According to the formula T2=J*a_minus, J is the vehicle inertia and a_minus is the braking deceleration. Then, according to the initial vehicle speed v0 set by the drive motor 2, the linear velocity vw of the tire model is obtained as vw=(v0 / R-v_minus)*R, where R is the wheel radius and v_minus is the vehicle speed of the vehicle model at this moment. Then, the vehicle slip ratio x2 of the simulated vehicle at this moment is obtained, x2=(v_minus-vw) / v_minus. According to the magic tire formula Fx=D*sin[C*arctan{B*xE(B*x-arctan(B*x))}], the longitudinal force Fx of the wheel at this moment is obtained. Then, the vertical force Fz of the wheel is calculated as Fz=M*g*(Lr+a_minus*hg / g) / L, where M is the total vehicle mass, Lr is the distance from the rear axle to the center of gravity, hg is the height of the center of gravity, and L is the wheelbase. Then, the wheel friction coefficient y=Fx / Fz is obtained. The vehicle friction torque T_wheel is calculated using T_wheel=Fx*R, where Fx is the longitudinal force of the wheel and R is the wheel radius.

[0041] To construct the test bench friction torque-test bench slip characteristic T1-x1 curve and the vehicle friction torque-vehicle slip characteristic T_wheel-x2 curve, it is necessary to calibrate the test bench and dynamic model to obtain the functional relationship s_ff between the test bench friction torque T1 and the vehicle friction torque T_wheel. The ultimate control objective is to make the test bench friction torque-test bench slip characteristic T1-x1 curve fit the vehicle friction torque-vehicle slip characteristic T_wheel-x2 curve.

[0042] Since the previous experiment had measured the variation of the test bench friction torque T1 with the clutch 12 opening as shown in the graph T1-s, the target opening s_des of the test bench was derived from the variation graph T1-s and s_ff of the vehicle friction torque T_wheel at that time. The derivation logic is to first fit the test bench slip ratio x1 and the vehicle slip ratio x2, and then fit the relationship between the test bench friction torque T1 and the vehicle friction torque T_wheel. Since there is a relationship of s_ff between the test bench friction torque T1 and the vehicle friction torque T_wheel, and the variation graph T1-s has been established, the target opening s_des is finally derived. Then, the servo motor 51 is controlled to make the slip simulation device 5 move closer to the target opening s_des.

[0043] The aforementioned vehicle friction torque T_wheel represents an ideal situation. However, due to factors such as the stiffness of the test bench and signal delay in the controller during actual experiments, the wheel friction torque T_wheel cannot be directly used as the target torque of the test bench. It is necessary to derive the dynamic mapping relationship between the test bench and the vehicle model to correct T_wheel, and the corrected T_wheel is then used as the target torque of the test bench.

[0044] The correction process is as follows: The test bench utilizes the test bench friction torque T1=F*Z*μ*Rc of clutch 12 to simulate the wheel friction torque T_wheel=F_z*y*R; Z is the number of clutch faces; Rc is the effective friction radius; y is the wheel friction coefficient, calculated from the above formula wheel friction coefficient y=Fx / Fz. The relationship between the normal force F and the wheel friction coefficient y needs to be determined. This is derived using a mapping experiment method. Due to the complexity and variability of roads in actual vehicle operation, a steady-state road surface is initially used as a prerequisite. Further optimization can be achieved by setting an alternating road surface later. The specific derivation process is as follows: In the experiment, the dynamic friction coefficient μ of the test bench was first determined. According to the research paper, its functional relationship with the rotational speed w is μ = μstatic * (μ(w)) / μ_w, where μstatic is the static friction coefficient, μ_w is the orthogonality coefficient determined by the normal pressure, rotational speed, and temperature, and μ(w) is the sum of polynomials. The value from the reference paper was used for this setting. This test bench is suitable for high-speed braking conditions and is therefore greatly affected by the rotational speed. Different rotational speeds were set in the experiment to obtain the coefficients in the formula and measure the static friction coefficient to estimate the dynamic friction coefficient at the specified speed. Based on the calibrated dynamic friction coefficient μ, the normal pressure F of the test bench was estimated. For example, using a clutch as the slip simulation device 5, the normal pressure F = T1 / Z * μ * Rc. This leads to the functional relationship between the normal pressure F and the tire friction coefficient y, F=f1(y). In the control model, this relationship is typically represented by a calibration map. The pressure value F corresponding to the friction torque is obtained when measuring the friction characteristic curve on the test bench. Then, the friction coefficient y under the change of wheel friction torque is calculated using the model, resulting in the map corresponding to Fy. Finally, the target pressure on the test bench is obtained from T_wheel=f2(y). ; Considering the influence of factors such as the mechanical stiffness of the test bench and the sensor signal response in actual situations, the dynamic equation of the test bench is obtained through experimental calibration. Then, the target friction torque T_des of the test bench is calculated from the target pressure F_des obtained after dynamic mapping. Finally, the target opening s_des is obtained using the torque characteristic diagram T1-s obtained above. In the experiment, the same braking force signal can be input via EMB to measure the slip curves T1-x1 at different openings. The slip curve T_wheel-x2 closest to the vehicle model is selected, and the opening of clutch 12 is recorded as the initial value. Generally, a position near the zero point of T1 is selected. In the experiment, the position change of the lead screw is roughly as follows: first, it moves rapidly away from the zero point to increase torque, and then it slowly approaches the zero point to decrease torque. The torque change pattern conforms to the shape of the wheel braking curve. Since the static friction torque needs to be overcome when clutch 12 engages in the experiment, a dead zone compensation module is also required in the control model to eliminate the influence of static friction torque.

[0045] In the friction torque control loop: The target opening s_des is divided into two parts: feedforward and feedback. s_des = s_ff + s_fb. The feedforward part s_ff is derived from the functional relationship between the test bench friction torque T1 and the vehicle friction torque T_wheel. The feedback value s_fb can be adjusted by PI control. ; Indicates proportional gain; Indicates the integral gain; τ is the time constant; Indicates the time; set as needed.

[0046] The target opening s_des is used as the target displacement of screw 54, and then the target position p_des of servo motor 51 is obtained. The target position p_des of servo motor 51 is sent to the motor driver via the dspace controller to control servo motor 51. The motor position loop is debugged in the existing motor control software, and then the target speed v_des of servo motor 2 is obtained.

[0047] Since the previous experiment has measured the variation of the test bench friction torque T1 with the clutch 12 opening (T1-s), the test bench friction torque T1 is controlled by adjusting the clutch 12 opening s to achieve the target torque. The target opening s_des is obtained from the target torque, thus realizing the transformation from friction torque control to motor position control.

[0048] In the motor position control loop, the target opening s_des is input into the motor position control loop to obtain the target speed v_des. The target speed v_des can be calculated using the following formula: v_des = Gain1 * (Pp * ... s+Vff*v_profile+Aff*a_profile), s is the target opening difference, which is the target opening s_des minus the current opening; Gain1 is the amplifier setting parameter; Pp is the position scaling factor; Vff and Aff are the feedforward coefficients for velocity and acceleration, respectively; v_profile and a_profile are determined by the maximum trajectory velocity and acceleration in the trajectory generator.

[0049] In the speed control loop, the target speed v_des is input into the current control loop to obtain the target current I_des. Vp and Vi are the proportional and integral coefficients of the speed control loop, respectively; V represents the target speed difference, calculated by subtracting the current speed from the target speed v_des; τ is the time constant. Indicates time. Finally, the target current I_des is input into the current control loop, according to... Cp and Ci are the coefficients of the current control loop; I represents the target current difference, determined by the target current. Subtract the current; τ is the time constant; Indicates time. The required voltage signal is output to the driver to control servo motor 2 to the appropriate position.

[0050] In this embodiment, feedback signals are also provided, including current feedback, speed feedback, and position feedback signals, to adjust the corresponding closed loop. The actual displacement output by the actuator acts on the test bench, affecting the frictional torque T1. The dynamic characteristics of the motor-screw actuator must also be considered. If there is a delay or oscillation in the response, an adjustment compensation module needs to be added so that s_des = s_ff + s_fb + s_v, where s_v is the compensation value provided by the dynamic compensation module. During the closed-loop debugging of the torque loop, the impact of frictional heat on the control strategy may also need to be considered, requiring the addition of a test bench frictional heat estimation module. Further experimental verification is needed to refine and debug the specific control strategy.

[0051] Meanwhile, during the control strategy verification phase, based on the established closed-loop model, the EMB prototype needs to send different clamping force signals to verify its transient characteristics, or input a series of alternating road surface adhesion coefficients to verify the robustness of the control strategy and complete further optimization and adjustment.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A brake test bench for simulating wheel slip, characterized in that The device includes a bench controller (1), a drive motor (2), a clutch (12), a vehicle body inertia simulation module (3), a slip simulation device (5), a wheel inertia simulation module (6), and a brake actuator (9). The drive motor (2), clutch (12), vehicle body inertia simulation module (3), slip simulation device (5), wheel inertia simulation module (6), and brake actuator (9) are arranged coaxially in sequence. The bench controller (1) is communicatively connected to the drive motor (2), clutch (12), vehicle body inertia simulation module (3), slip simulation device (5), wheel inertia simulation module (6), and brake actuator (9). The vehicle body inertia simulation module (3) and the wheel inertia simulation module (6) transmit the collected data to the bench controller (1), and the bench controller (1) uses a multi-closed control strategy to control the action of the slip simulation device (5) based on the data.

2. A brake test bench for simulating wheel slip according to claim 1, characterized in that The skid simulation device (5) includes a skid control unit and a power transmission unit. The skid control unit is communicatively connected to the bench controller (1). The skid control unit is movably connected to the power transmission unit. The power transmission unit is coaxially arranged with the vehicle body inertia simulation module (3) and the wheel inertia simulation module (6).

3. A braking test bench for simulating wheel slippage according to claim 2, characterized in that, The test bench includes a first shaft (10) and a second shaft (11). The power transmission unit is connected to the first shaft (10) and the second shaft (11) respectively. The first shaft (10) and the second shaft (11) are coaxial. The drive motor (2), the clutch (12) and the vehicle body inertia simulation module (3) are installed on the first shaft (10) in sequence. The wheel inertia simulation module (6) and the brake actuator (9) are installed on the second shaft (11) in sequence.

4. A braking test bench for simulating wheel slippage according to claim 3, characterized in that, The power transmission unit includes a friction disc (56), a pressure disc (57), a diaphragm spring (58), a clamping spring (59), and a release bearing (60). The first shaft (10) is connected to the friction disc (56). The release bearing (60) is connected to the pressure disc (57) through the diaphragm spring (58) and the clamping spring (59). The pressure disc (57) and the friction disc (56) may or may not be in contact. The release bearing (60) is mounted on a second shaft (11). The second shaft (11) passes through the pressure disc (57), the diaphragm spring (58), the clamping spring (59), and the release bearing (60).

5. A braking test bench for simulating wheel slippage according to claim 4, characterized in that, The sliding control unit includes a servo motor (51), a gear pair (52), a nut (53), a screw (54), and a pressure rod (55). The gear pair (52) is connected to the servo motor (51) and the nut (53) respectively. The nut (53) is mounted on the screw (54) and cooperates with the screw (54) for transmission. The pressure rod (55) is connected to the screw (54) and the release bearing (60) respectively.

6. A slip control method based on a braking test bench for simulating wheel slip as described in any one of claims 1-5, characterized in that, The method includes: S1. The bench controller (1) causes the drive motor (2) to reach a preset speed and then disengages the clutch (12), while simultaneously causing the brake actuator (9) to clamp the sliding simulation device (5). S2, The bench controller (1) calculates the vehicle friction torque T_wheel based on the data from the vehicle body inertia simulation module (3) and the wheel inertia simulation module (6); S3. The vehicle friction torque T_wheel is used as the input signal of the multi-closed-loop control strategy, and the action of the slip simulation device (5) is controlled by combining the input signal and the feedback signal of the slip simulation device (5).

7. The method according to claim 6, characterized in that, The multi-closed-loop control strategy includes friction torque control, which includes a feedforward unit and a feedback unit. The vehicle friction torque T_wheel is input to the feedforward unit, and the vehicle friction torque T_wheel and the feedback signal of the slip simulation device (5) are input to the feedback unit. The output signals of the feedforward unit and the feedback unit jointly adjust the target opening s_des.

8. The method according to claim 7, characterized in that, The multi-closed-loop control strategy also includes motor position control, which adjusts the motor position and obtains the target speed v_des based on the target opening s_des and the feedback signal from the slip simulation device (5).

9. The method according to claim 8, characterized in that, The multi-closed-loop control strategy also includes speed control, which adjusts the motor speed and obtains the target current I_des based on the target speed v_des and the feedback signal from the slip simulation device (5).

10. The method according to claim 9, characterized in that, The multi-closed-loop control strategy also includes current control, which adjusts the motor current and obtains the target voltage u_des based on the target current I_des and the feedback signal of the slip simulation device (5), and adjusts the operation of the slip simulation device (5) based on the target voltage.

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