A steering device for a driving simulator and its control method

Abstract

The present invention discloses a steering device for a driving simulator and its control method. The steering device includes a steering wheel, a steering wheel connecting shaft, an input coupling, an input shaft, a torsion bar, an output shaft, a motor coupling, a motor, a torque-angle sensor, a controller, and a power supply. One end of the steering wheel is connected to the steering wheel connecting shaft, and the other end of the steering wheel connecting shaft is connected to the input shaft through the input coupling. The input shaft is connected to the output shaft through the torsion bar, and the output shaft is connected to the rotating shaft of the motor through the motor coupling. The torque-angle sensor is used to obtain the angle and torque signals of the steering wheel and send them to the controller. The controller is used to receive the angle and torque signals and control the motor to output a target torque. The power supply is used to supply power to the controller. The steering device of the present invention effectively avoids the direct transmission of the motor jitter to the steering wheel, and its control method can realistically simulate the steering wheel feedback force feeling, improving the driving experience of the driver.

Description

Technical Field

[0001] The present invention relates to an automotive steering system, and in particular to a steering device for a driving simulator and a control method thereof. Background Art

[0002] With the rapid development of technologies such as the Internet and artificial intelligence, autonomous driving technology has become one of the hottest trends in the current development of automobiles. However, due to problems such as test costs, laws and regulations, test sites, abnormal test conditions, and test duration, the development and test verification of some autonomous driving algorithms need to be completed in a virtual environment. Therefore, the research on driving simulators is of great significance in the development and test process of autonomous driving technology. Among them, the steering wheel force feedback provided by the driving simulator to the driver is an important part that determines the realism of the simulation effect of the driving simulator.

[0003] Most of the steering wheel feedback torques in driving simulators are realized by directly connecting the motor to the steering wheel. This direct motor connection method has the advantages of simple structure, convenient control, and strong reliability. However, due to the absence of devices such as mechanical damping, directly connecting the steering wheel to the motor will transmit the motor's jitter to the steering wheel, affecting the driver's driving experience. Summary of the Invention

[0004] In order to solve the above problems, the main object of the present invention is to provide a steering device for a driving simulator, which avoids transmitting the motor's jitter to the steering wheel and improves the driver's driving experience.

[0005] Another object of the present invention is to provide a control method for a steering device for a driving simulator. By obtaining the torque and rotation angle of the steering wheel and using a controller to control the target output torque of the motor, the driver can obtain a realistic steering wheel feedback force feeling.

[0006] According to the above object, the technical solution adopted by the present invention is a steering device for a driving simulator, including: a steering wheel, a steering wheel connecting shaft, an input coupling, an input shaft, a torsion bar, an output shaft, a motor coupling, a motor, a torque and rotation angle sensor, a controller, and a power supply;

[0007] One end of the steering wheel is connected to one end of the steering wheel connecting shaft, the other end of the steering wheel connecting shaft is connected to the input shaft through the input coupling, the input shaft is connected to the output shaft through the torsion bar, and the output shaft is connected to the rotating shaft of the motor through the motor coupling;

[0008] The torque and rotation angle sensor is arranged between the input shaft and the output shaft, and is used for obtaining the rotation angle and torque signals of the steering wheel and sending them to the controller;

[0009] The controller is electrically connected to the power supply, the motor, and the torque-angle sensor respectively, and is configured to receive the angle and torque signals and control the motor to output a target torque.

[0010] The power supply is used to supply power to the controller.

[0011] Further, the steering device further includes a column upper sleeve, a sensor upper housing, a sensor lower housing, and a motor connection flange that are fixedly connected in sequence; the steering wheel connecting shaft is rotatably supported in the column upper sleeve through a bearing; the input shaft is rotatably supported in the sensor upper housing through a bearing; the output shaft is rotatably supported in the sensor lower housing through a bearing; and the motor connection flange is fixedly connected to the motor.

[0012] Further, the torsion bar is coaxially disposed in the inner holes of the input shaft and the output shaft, and one end of the torsion bar is fixedly connected to the input shaft through a cylindrical pin, and the other end is in interference fit with the inner hole of the output shaft.

[0013] Still further, a stepped groove is provided in the opening of the input shaft facing the output shaft, and the end of the output shaft facing the input shaft penetrates into the stepped groove and is in clearance fit with the stepped groove; a bushing is further provided in the stepped groove.

[0014] Further, a column coupling is provided at one end of the output shaft connected to the motor, the column coupling is connected to the motor coupling, and the output shaft is connected to the rotating shaft of the motor through the column coupling and the motor coupling. Specifically, the column coupling is sleeved on the end of the output shaft. In a preferred embodiment, a coupling elastic block is further provided in the opening at one end of the motor coupling facing the output shaft.

[0015] According to the above object, the technical solution adopted by the present invention further provides a control method for a steering device of a driving simulator, including the following steps:

[0016] Obtain the angle and torque signals of the steering wheel;

[0017] The controller controls the target torque of the motor according to the actual torque of the steering wheel through an inner loop control circuit for controlling current and an outer loop control circuit for controlling torque.

[0018] Further, the inner loop control circuit includes two parts: inner loop feedforward control and inner loop feedback control; wherein the input of the inner loop feedforward control part is the target current I controlled by the outer loop control circuit req , and then the PWM feedforward control quantity PWM corresponding to the target current I is obtained by querying a pre-calibrated "current - PWM" table req FF; The PWM feedforward control quantity PWM FF is summed with the PWM feedback control quantity PWM FB to obtain the total PWM control quantity PWM req ; This total PWM control quantity PWM req is filtered by moving average to obtain the motor PWM value input to the motor; the motor current corresponding to this motor PWM value is the actual motor current I a ;

[0019] The input of the inner loop feedback control part is the feedback input current, that is, the difference between the target current Ireq and the actual motor current Ia after moving average filtering; this feedback input current is converted by a PID controller to obtain the PWM feedback control quantity PWM FB .

[0020] Furthermore, the "current - PWM" table is obtained through a calibration test; in the calibration test, the motor input current is controlled to change slowly and linearly, and the corresponding PWM values are read to obtain the motor's "current - PWM" table.

[0021] Further, the outer loop control circuit includes three parts: outer loop feedforward, outer loop feedback, and damping compensation; the input of the outer loop feedforward part is the target torque T t ; The target torque T t obtains the outer loop feedforward current control quantity I after querying the pre - calibrated "torque - current" table FF ;

[0022] The input of the outer loop feedback part is the difference between the target torque T t and the actual torque T a . The difference is input to a PID controller after Kalman filtering to obtain the outer loop feedback current control quantity I FB .

[0023] The input of the damping compensation part is the product of the derivative of the actual torque signal and the damping coefficient to obtain the outer loop damping compensation current control quantity I damp ;

[0024] The outer loop feedforward current control quantity I FF , the outer loop feedback current control quantity I FB , and the outer loop damping compensation current control quantity I damp are summed to obtain the target current I input to the inner loop control circuit req .

[0025] Furthermore, the "torque - current" table is obtained through a calibration test; in the calibration test, the motor input current is controlled to change slowly and linearly, and the corresponding actual torque values are read to obtain the motor's "torque - current" table.

[0026] Due to the above technical solution, the beneficial effects achieved by the present invention are as follows: In the present invention, the steering wheel is connected to the motor through intermediate components such as a steering wheel connecting shaft, an input coupling, an input shaft, a torsion bar, an output shaft, and a motor coupling. The torsion bar is used to transmit torque, avoiding the direct connection between the steering wheel and the motor, effectively reducing the transmission of motor jitter to the steering wheel, and improving the driving experience of the driver; by obtaining the steering wheel angle and torque signals in real time through a torque-angle sensor, the controller can control the target torque output by the motor, providing a more realistic steering wheel force feedback to the driver, and further improving the simulation effect of the driving simulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a structural cross-sectional view of a steering device for a driving simulator according to an embodiment of the present invention.

[0028] Figure 2 is a schematic diagram of the principle of a control method for a steering device according to an embodiment of the present invention.

[0029] Figure 3 is a schematic diagram of the real-time simulation result of the steering wheel according to an embodiment of the control method of the present invention (torque (Nm)-time (s) curve graph).

[0030] Figure 4 is a schematic diagram of the real-time simulation result of the steering wheel according to an embodiment of the control method of the present invention (current (A)-time (s) curve graph).

[0031] In the drawings: 1-steering wheel; 2-steering wheel connecting shaft; 3-retaining ring; 4-deep groove ball bearing; 5-upper tube column sleeve; 6-tube column lock; 7-input shaft coupling; 8-cylindrical pin; 9-input shaft; 10-upper sensor housing; 11-lower sensor housing; 12-motor connection flange; 13-motor; 14-retaining ring; 15-torsion bar; 16-retaining ring; 17-deep groove ball bearing; 18-retaining ring; 19-bushing; 20-torque-angle sensor; 21-output shaft; 22-deep groove ball bearing; 23-tube column connecting shaft; 24-connecting shaft elastic block; 25-motor coupling; 30-controller; 40-power supply. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art under the premise of equivalent changes and modifications shall fall within the protection scope of the present invention.

[0033] Refer toFigure 1 , this embodiment provides a steering device for a driving simulator, mainly including: a steering wheel 1, a steering wheel connecting shaft 2, an input coupling 7, an input shaft 9, a torsion bar 15, an output shaft 21, a motor coupling 25, a motor 13, a torque angle sensor 20, a controller 30 and a power supply 40.

[0034] In this embodiment, one end of the steering wheel 1 is connected to the steering wheel connecting shaft 2, and the other end of the steering wheel connecting shaft 2 is connected to the input shaft 9 through the input coupling 7. The steering wheel connecting shaft 2 is fixedly supported in the upper sleeve 5 of the column through a deep groove ball bearing 4 and a circlip 3. The input shaft 9 is connected to the output shaft 21 through a torsion bar 15, and the output shaft 21 is connected to the rotating shaft of the motor 13 through a motor coupling 7. The input shaft 9 is fixed in the upper sensor housing 10 through a deep groove ball bearing 17 and a circlip 16, and the output shaft 21 is fixed in the lower sensor housing 11 through a deep groove ball bearing 22. The torque angle sensor 20 is arranged between the input shaft 9 and the output shaft 21, and the torque angle sensor 9 is located in the lower sensor housing 1, and is used to obtain the rotation angle and torque signals of the steering wheel 1 and send them to the controller 40. In this embodiment, the upper sleeve 5 of the column, the upper sensor housing 10, the lower sensor housing 11 and the motor connection flange 12 are fixedly connected together in sequence, and the motor connection flange 12 is fixedly connected to the motor 13. The column lock 6 is used for locking and unlocking the steering of the steering wheel.

[0035] The torsion bar 15 is coaxially arranged in the inner holes of the input shaft 9 and the output shaft 21, and one end of the torsion bar 15 is fixedly connected to the input shaft 9 through a cylindrical pin 08, and the other end is in interference fit with the inner hole of the output shaft 21. A stepped groove is provided in the opening of the input shaft 09 facing the output shaft 21, and the end of the output shaft 21 facing the input shaft 9 penetrates into the stepped groove and is in clearance fit with the stepped groove; a bushing 19 is also provided in the stepped groove. In this embodiment, the bushing 19 is a metal sleeve, preferably a copper sleeve. The output shaft 21 is provided with a column coupling 23 at one end connected to the motor 13, the column coupling 23 is connected to the motor coupling 25, and the output shaft 21 is connected to the rotating shaft of the motor 13 through the column coupling 23 and the motor coupling 25. In this embodiment, the column coupling 23 is sleeved on the end of the output shaft 21. An elastic coupling block 24 is also provided in the opening of one end of the motor coupling 25 facing the output shaft 21.

[0036] The controller 30 is electrically connected to the power supply 40, the motor 13 and the torque angle sensor 20 respectively, and is used to receive the rotation angle and torque signals obtained by the torque angle sensor and control the motor 08 to output a target torque. The power supply 40 is used to supply power to the controller 40. In this embodiment, the controller uses Freescale MC9S12G, and the torque angle sensor uses Jingliang Meas FGPFCA7300.

[0037] For the steering device adopting the above structure, when the motor 13 outputs torque according to the control of the controller, the torque is transmitted to one end of the torsion bar 5 through the motor coupling 25, the pipe column coupling 23 and the output shaft 21, and then through the torsion bar 5, the torque is transmitted to the input shaft 9 through the other end, and the torque is transmitted to the steering wheel through the input coupling 7 and the steering wheel connecting shaft 2, so that the driver can obtain the steering wheel feedback force feeling. Since the intermediate components have a certain damping effect, the jitter generated by the motor is greatly reduced when transmitted to the steering wheel, thus effectively improving the driving experience of the driver.

[0038] Please refer to Figure 2 , in order to enable the driver to obtain a more realistic steering wheel feedback force feeling, the present invention also provides a control method for a steering device of a driving simulator, and the control method includes the following steps:

[0039] Step 1: Obtain the steering angle and torque signals of the steering wheel;

[0040] In this step, the steering angle and torque signals of the steering wheel are mainly obtained in real time by the torque angle sensor and sent to the controller. During the process that the rotating shaft of the motor 13 rotates to output torque to the steering wheel 1, the torsion bar 5 transmits the torque. Due to the relative rotation between the output shaft 21 and the input shaft 9, the torque angle sensor can obtain the actual torque of the steering wheel. The motor can be controlled by using the difference between the target torque and the actual torque of the motor.

[0041] Step 2: The controller controls the target torque of the motor through an inner loop control circuit for controlling current and an outer loop control circuit for controlling torque according to the actual torque of the steering wheel.

[0042] In this step, the controller receives the steering angle and torque signals of the steering wheel obtained by the torque angle sensor, and mainly controls the target torque of the motor by controlling the current and torque of the motor, so that the steering wheel can obtain a more realistic feedback force feeling through the controller and simulation.

[0043] In step 2, the inner loop control circuit includes two parts: inner loop feedforward control and inner loop feedback control; wherein the input of the inner loop feedforward control part is the target current I req controlled by the outer loop control circuit, and then the PWM feedforward control quantity PWM req corresponding to the target current I FF is obtained by querying the pre-calibrated "current - PWM" table; the PWM feedforward control quantity PWM FF is summed with the PWM feedback control quantity PWM FB to obtain the total PWM control quantity PWM req ; this total PWM control quantity PWM reqThe motor PWM value input to the motor is obtained after moving average filtering; the motor current corresponding to this motor PWM value is the actual motor current I a ;

[0044] The input of the inner loop feedback control part is the feedback input current, that is, the difference between the target current Ireq and the actual motor current Ia after moving average filtering; the PWM feedback control quantity PWM is obtained after the conversion of this feedback input current by the PID controller FB 。

[0045] Among them, the "current - PWM" table is obtained through calibration tests; in the calibration test, the motor input current is controlled to change slowly and linearly, and the corresponding PWM values are read, so as to obtain the "current - PWM" table of this motor

[0046] In this embodiment, the outer loop control circuit includes three parts: outer loop feedforward, outer loop feedback, and damping compensation; the input of the outer loop feedforward part is the target torque T t ; the target torque T t After querying the pre - calibrated "torque - current" table, the outer loop feedforward current control quantity I is obtained FF ;

[0047] The input of the outer loop feedback part is the difference between the target torque T t and the actual torque T a , and the difference is input to the PID controller after Kalman filtering, so as to obtain the outer loop feedback current control quantity I FB 。

[0048] The input of the damping compensation part is the product of the differentiated actual torque signal and the damping coefficient, so as to obtain the outer loop damping compensation current control quantity I damp ;

[0049] The outer loop feedforward current control quantity I FF , the outer loop feedback current control quantity I FB , and the outer loop damping compensation current control quantity I damp are summed to obtain the target current I input to the inner loop control circuit req 。

[0050] Among them, the "torque - current" table is obtained through calibration tests; in the calibration test, the motor input current is controlled to change slowly and linearly, and the corresponding actual torque values are read, so as to obtain the "torque - current" table of the motor

[0051] According to the above - mentioned control method, the specific implementation process of using this control method for real - time simulation of the steering wheel feedback force feeling in this embodiment mainly includes the following steps

[0052] S1. Calibrate to obtain the "current - PWM" table

[0053] Control the input current of the motor to change slowly and linearly from 0 A to 12 A, record the corresponding PWM values and actual current values, so as to obtain the "current - PWM" table of this motor.

[0054] S2. Calibrate to obtain the "torque - current" table:

[0055] Control the input current of the motor to change slowly and linearly from 0 A to 12 A, record the corresponding actual torque values and actual current values, so as to obtain the "torque - current" table of this motor.

[0056] S3. Write the control program:

[0057] Use the C language to implement the above - mentioned control method of the steering device for the driving simulator and write it into the controller. This program contains the "current - PWM" table in S1 and the "torque - current" table in S2.

[0058] S4. Tune the PID parameters:

[0059] According to the engineer's experience, tune to obtain the current - control PID parameters of the inner - loop control loop and the torque - control PID parameters of the outer - loop control loop. In this embodiment, after tuning, the current - control PID parameters are: the P value is 30; the I value is 12; the D value is 0; the torque - control PID parameters are: the P value is 15; the I value is 8; the D value is 14.

[0060] S5. Performance test

[0061] Use the host computer to send a sinusoidal target torque signal with an amplitude of 5 Nm to the controller, the signal periods are 5 s, 10 s, and 15 s, calculate the mean - square error value MSE between the actual torque and the target torque. If the MSE values obtained from the three tests are all less than 0.2, then the steering device and its control method for the driving simulator involved in the present invention are effective. After testing, the MSE values obtained from the three tests in this embodiment are 0.0152, 0.143, and 0.101 respectively, all less than the preset threshold 0.2.

[0062] Please refer to Figure 3 and Figure 4 , which show the results of realizing the real - time simulation of the steering wheel by using the above - mentioned steering device and control method, and are represented by the torque (Nm) - time (s) curve and current (A) - time (s) respectively. In the figure, the target current curve and the actual current curve basically coincide, and the actual torque curve is smoother and has a smaller fluctuation amplitude than the target torque curve in the time period of 10 - 20 s. It shows that the steering device and its control method for the driving simulator in this embodiment more realistically simulate the steering wheel feedback force feeling, and effectively improve the steering wheel jitter, making the driver's driving experience more comfortable.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention; at the same time, the above description should be understandable and implementable by those with ordinary knowledge in the relevant technical field. Therefore, other equivalent changes or modifications completed without departing from the concepts disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A control method for a steering device of a driving simulator, the steering device for the driving simulator comprising: A steering wheel (01), a steering wheel connecting shaft (02), an input coupling (07), an input shaft (09), a torsion bar (15), an output shaft (21), a motor coupling (25), a motor (13), a torque angle sensor (20), a controller (30) and a power supply (40); One end of the steering wheel (01) is connected to the steering wheel connecting shaft (02), the other end of the steering wheel connecting shaft (02) is connected to the input shaft (09) through the input coupling (07), the input shaft (09) is connected to the output shaft (21) through the torsion bar (15), and the output shaft (21) is connected to the rotating shaft of the motor (13) through the motor coupling; The torque angle sensor (20) is arranged between the input shaft (09) and the output shaft (21) for acquiring the steering angle and torque signals of the steering wheel (01) and sending them to the controller (30); The controller (30) is electrically connected to the power supply (40), the motor (13) and the torque angle sensor (20) respectively for receiving the steering angle and torque signals and controlling the motor to output a target torque; The power supply (40) is used to supply power to the controller (30); It is characterized in that it includes the following steps: Acquiring the steering angle and torque signals of the steering wheel; The controller controls the target torque of the motor according to the actual torque of the steering wheel through an inner loop control circuit for controlling current and an outer loop control circuit for controlling torque; the inner loop control circuit includes two parts: inner loop feedforward control and inner loop feedback control; wherein the input of the inner loop feedforward control part is the target current I obtained by the control of the outer loop control circuit req , and then the target current I req corresponding PWM feedforward control quantity PWM FF is obtained by querying a pre-calibrated "current - PWM" table; the PWM feedforward control quantity PWM FF is summed with the PWM feedback control quantity PWM FB to obtain the total PWM control quantity PWM req ; this total PWM control quantity PWM req is filtered by moving average to obtain the motor PWM value input to the motor; the motor current corresponding to this motor PWM value is the actual motor current I a ; The input of the inner loop feedback control part is the feedback input current, that is, the difference between the target current Ireq and the actual motor current Ia after moving average filtering; the PWM feedback control quantity PWM is obtained after the conversion of the PID controller for the feedback input current FB .

2. The control method of the steering device for a driving simulator according to claim 1, characterized in that, The steering device further includes a column upper sleeve (05), a sensor upper housing (10), a sensor lower housing (11) and a motor connection flange (12) which are fixedly connected in sequence; the steering wheel connecting shaft (02) is rotatably supported in the column upper sleeve (05) through a bearing; the input shaft (09) is rotatably supported in the sensor upper housing (10) through a bearing; the output shaft (21) is rotatably supported in the sensor lower housing (11) through a bearing; the motor connection flange (12) is fixedly connected to the motor (13).

3. The control method of the steering device for a driving simulator according to claim 1, characterized in that, The torsion bar (15) is coaxially arranged in the inner holes of the input shaft (09) and the output shaft (21), and one end of the torsion bar (15) is fixedly connected to the input shaft (09) through a cylindrical pin, and the other end is in interference fit with the inner hole of the output shaft (21).

4. The control method of the steering device for a driving simulator according to claim 3, characterized in that, A stepped groove is arranged in the opening of the input shaft (09) facing the output shaft (21), and the end of the output shaft (21) facing the input shaft (09) penetrates into the stepped groove and is in clearance fit with the stepped groove; a bushing (19) is also arranged in the stepped groove.

5. The control method of the steering device for a driving simulator according to claim 1, characterized in that, A column coupling (23) is arranged at one end of the output shaft (21) connected to the motor (13), the column coupling (23) is connected to the motor coupling (25), and the output shaft (21) is connected to the rotating shaft of the motor (13) through the column coupling (23) and the motor coupling (25).

6. The control method of the steering device for a driving simulator according to claim 1, characterized in that, The "current - PWM" table is obtained through a calibration test; in the calibration test, the input current of the motor is controlled to change slowly and linearly, and the corresponding PWM value is read, so as to obtain the "current - PWM" table of the motor.

7. The control method of the steering device for a driving simulator according to claim 1, characterized in that, The outer loop control circuit includes three parts: outer loop feedforward, outer loop feedback, and damping compensation; the input of the outer loop feedforward part is the target torque T t ; the target torque T t After querying the pre-calibrated "torque-current" table, the outer loop feedforward current control quantity I is obtained FF ; The input of the outer loop feedback part is the target torque T t and the actual torque T a The difference between them is input into the PID controller after passing through the Kalman filter, so as to obtain the outer loop feedback current control quantity I FB； The input of the damping compensation part is the product of the differentiated actual torque signal and the damping coefficient, so as to obtain the outer-loop damping compensation current control quantity I damp； The outer-loop feedforward current control quantity I FF , the outer-loop feedback current control quantity I FB , the outer-loop damping compensation current control quantity I damp are summed to obtain the target current I req fed to the inner-loop control circuit.

8. The control method of the steering device for a driving simulator according to claim 7, characterized in that, The "torque-current" table is obtained through a calibration test; in the calibration test, the input current of the motor is controlled to change slowly and linearly, and the corresponding actual torque value is read, so as to obtain the "torque-current" table of the motor.

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