Steer-by-wire system and angle control method thereof

Abstract

The application discloses a steer-by-wire system and an angle control method thereof, and the system comprises a feel simulator and a steering actuator, the feel simulator comprises a torque sensor, a feel simulator controller, a feel simulator motor, a feel simulator transmission mechanism and a feel simulator angle sensor, and the steering actuator comprises a steering actuator controller, a steering actuator angle sensor, a steering actuator transmission mechanism and a steering actuator motor, wherein the angle of the steering actuator is dynamically consistent with the steering angle obtained by the feel simulator. The application realizes that the road surface actuator in the steer-by-wire system follows the feel simulator, so that the response characteristic of the steering actuator in the steer-by-wire system to the input angle of the driver is improved, the response accuracy of the driver in the dynamic input scene is improved, and the lateral control precision of the vehicle is improved.

Description

Technical Field

[0001] This invention belongs to the field of automotive steer-by-wire technology, specifically relating to a steer-by-wire system and a method for controlling the angle of the steer-by-wire system. Background Technology

[0002] The shift in the focus of the automotive industry from traditional internal combustion engines to new energy vehicles is an inevitable trend. New energy vehicles bring not only changes to the power system, but also increasingly higher requirements for drive-by-wire technology.

[0003] Currently, steer-by-wire systems are a key technology in automotive chassis development. They consist of a hand-feed simulator and a steering actuator. The hand-feed simulator connects to the steering wheel, transmitting the driver's steering angle commands to the steering actuator and simultaneously providing road feedback to the driver. The steering actuator, upon receiving the steering angle commands from the hand-feed simulator, rotates the wheels to achieve steering. The hand-feed simulator and steering actuator exchange information via electrical signals. However, due to the limitations of signal transmission cycles and the reaction time of the steering actuator in responding to angle commands, the ability of steer-by-wire systems to dynamically follow the driver's steering intentions is reduced compared to traditional steering systems, especially during high-speed cornering.

[0004] For example, CN107600168B discloses a steering control device and method for a steer-by-wire system. It calculates a compensated steering angle based on feedback steering angle and vehicle speed to variably control the output angle of the wheels. This method involves changing the target angle request, but the final accuracy will be affected. Another example is CN114261442B, which discloses a composite position control method for a steer-by-wire system. It divides the position control regulator into a first position regulator and a second position regulator, changing from traditional closed-loop feedback PI regulation to closed-loop feedback + open-loop feedforward control. However, using only engine speed as the feedforward signal for compensation is limited.

[0005] Therefore, steer-by-wire systems using traditional angle tracking methods do not have high accuracy in responding to dynamic driver input scenarios, which affects the lateral control precision of the vehicle. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an improved steer-by-wire system.

[0007] It also relates to an angle control method for a steer-by-wire system.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A steer-by-wire system includes a steering simulator and a steering actuator. The steering simulator includes a torque sensor, a steering simulator controller, a steering simulator motor, a steering simulator transmission mechanism, and a steering simulator angle sensor. The steering actuator includes a steering actuator controller, a steering actuator angle sensor, a steering actuator transmission mechanism, and a steering actuator motor. The angle of the steering actuator dynamically matches the steering angle obtained from the steering simulator. The torque T of the steering actuator motor is specified. sum For T LFW T FW T FB The sum of the three, T LFW Based on the torque sensor measurement value T of the hand feel simulator sensor The desired linear feedforward motor torque of the steering actuator is calculated through the linear feedforward control module; T FW The real-time steering actuator motor torque is obtained, and the desired feedforward motor torque of the steering actuator is calculated through the dynamic feedforward control module; T FB To determine the driver's steering angle θ hwa With steering actuator angle θ rwa The angle deviation is calculated, and the desired feedback motor torque of the steering actuator is obtained through the PID feedback control module.

[0010] Preferably, the driver applies torque to the steering wheel to rotate the hand-feel simulator transmission mechanism, thereby generating the desired steering angle, which is measured and output to the hand-feel simulator controller by the hand-feel simulator angle sensor; the driver's hand torque needs to overcome the resistance torque of the hand-feel simulator motor and is measured by the torque sensor, and is sent to the hand-feel simulator controller to control the hand-feel simulator motor to generate torque.

[0011] In some specific implementations, the hand-feel simulator controller, hand-feel simulator motor, hand-feel simulator transmission mechanism, and hand-feel simulator angle sensor are sequentially connected to form an internal closed loop.

[0012] According to a specific embodiment and preferred aspect of the present invention, the steering actuator controller receives the driver's steering angle from the hand-feel simulator controller, compares it with the steering actuator angle sensor, and controls the steering actuator motor to generate torque to drive the steering actuator transmission mechanism to move to a position consistent with the driver's steering angle so as to drive the steering wheel to rotate.

[0013] In some specific implementations, the steering actuator controller, steering actuator motor, steering actuator transmission mechanism, and steering actuator angle sensor are sequentially connected to form an internal closed loop.

[0014] According to another specific embodiment and preferred aspect of the invention, the linear feedforward control module designs calibrable curve coefficients KL(x) based on the real-time changing torque sensor signal T. sensor The desired linear feedforward motor torque T of the steering actuator is calculated. LFW As shown in the following formula:

[0015] T LFW =KL(x)×T sensor .

[0016] In some specific implementations, the steering actuator expects the feedforward motor torque T FW Simultaneously, the driver's steering angle θ is measured by the angle sensor of the hand-feel simulator. hwa And calculate the driver's turning speed. and acceleration

[0017] According to another specific embodiment and preferred aspect of the present invention, the dynamic feedforward control module calculates the driver's steering speed. and acceleration Based on the actual output torque T of the motor act Calculate the desired feedforward motor torque T of the steering actuator FW :

[0018]

[0019] In the above formula, M rwa For the equivalent mass of the steering actuator, B rwa Let η be the equivalent damping of the steering actuator, η be the transmission efficiency of the steering actuator, and G be the transmission ratio of the steering actuator transmission mechanism.

[0020] According to another specific embodiment and preferred aspect of the invention, the PID feedback control module controls the deviation (θ) between the driver's steering angle and the steering actuator angle. hwa -θ rwa ) Calculate and design a suitable k p k i k d Parameters are used to calculate the desired feedback motor torque T of the steering actuator. FB :

[0021] T FB =k p ×(θ hwa -θ rwa )+k i ×(θ hwa -θ rwa )+k d ×(θ hwa -θ rwa ).

[0022] Another technical solution of the present invention: an angle control method for a steer-by-wire system, which adopts the above-mentioned steer-by-wire system, and the control process of keeping the angle of the steering actuator dynamically consistent with the steering angle obtained by the hand feel simulator is as follows:

[0023] 1) Based on the torque sensor measurement value T of the hand-feel simulator sensor The desired linear feedforward motor torque of the steering actuator is calculated by a linear feedforward control module, wherein the linear feedforward control module is designed with a calibrable curve coefficient KL(x) based on the real-time changing torque sensor signal T. sensor The desired linear feedforward motor torque T of the steering actuator is calculated. LFW As shown in the following formula: T LFE =KL(x)×T sensor ;

[0024] 2) The driver's steering angle θ is measured by the angle sensor of the hand-feel simulator. hwa And calculate the driver's turning speed. and acceleration Simultaneously considering the real-time steering actuator motor torque, the desired feedforward motor torque T of the steering actuator is calculated through the dynamic feedforward control module. FW The dynamic feedforward control module calculates the driver's steering speed. and acceleration Based on the actual output torque T of the motor act Calculate the desired feedforward motor torque T of the steering actuator FW :

[0025] In the above formula, M rwa For the equivalent mass of the steering actuator, B rwa Let η be the equivalent damping of the steering actuator, η be the transmission efficiency of the steering actuator, and G be the transmission ratio of the steering actuator transmission mechanism.

[0026] 3) Based on the driver's steering angle θ hwa With steering actuator angle θ rwa The angle deviation is calculated by the PID feedback control module to obtain the desired feedback motor torque T of the steering actuator. FB The PID feedback control module measures the deviation (θ) between the driver's steering angle and the steering actuator angle. hwa -θ rw a) Calculate and design a suitable k p k i k d Parameters are used to calculate the desired feedback motor torque T of the steering actuator. FB :

[0027] T FB =k p ×(θ hwa -θ rwa )+k i ×(θ hwa -θ rwa )+k d ×(θ hwa -θ rwa );

[0028] 4) The final desired steering actuator motor torque T sum For T LFW T FW T FB The sum of these three factors is then sent to the steering actuator motor for execution. Therefore, the aforementioned angle control method improves the response characteristics of the steering actuator in a steer-by-wire system to the driver's input angle.

[0029] Due to the timeliness of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0030] Existing steer-by-wire systems suffer from low steering accuracy due to simply changing the target angle request. Furthermore, the compensation based solely on rotational speed as a feedforward signal is limited, failing to achieve dynamic consistency between the steering angle obtained from the hand-feel simulator and the steering actuator angle. This invention cleverly solves these shortcomings of existing systems through the overall design of the steer-by-wire system. With this system, the driver applies torque to the steering wheel to rotate the hand-feel simulator transmission mechanism, thereby generating the desired steering angle. This angle is measured by the hand-feel simulator angle sensor and output to the hand-feel simulator controller. Simultaneously, the driver's hand torque needs to overcome the resistance torque of the hand-feel simulator motor, which is measured by a torque sensor and sent to the hand-feel simulator controller. Internal closed-loop torque control then controls the hand-feel simulator motor to generate torque. At the same time, the steering actuator controller receives the driver's steering angle from the hand-feel simulator controller and compares it with the steering actuator angle sensor. It then controls the steering actuator motor to generate torque, moving the steering actuator transmission mechanism to a position consistent with the driver's steering angle to rotate the steering wheels. Therefore, this invention achieves dynamic consistency between the steering actuator angle and the steering angle obtained from the hand-feel simulator, ensuring that the road actuator in steer-by-wire follows the hand-feel simulator. This improves the response characteristics of the steering actuator to the driver's input angle in the steer-by-wire system, enhances the accuracy of the response to dynamic driver input scenarios, and improves the lateral control precision of the vehicle.

[0031] Specific real-time methods

[0032] Figure 1This is a schematic diagram of the steer-by-wire system of the present invention;

[0033] Figure 2 This is a schematic diagram of the working operation of the steer-by-wire system of the present invention.

[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description is provided below with reference to specific implementation methods. Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific implementation examples disclosed below.

[0035] like Figure 1 As shown, the steer-by-wire system involved in this embodiment includes a hand feel simulator and a steering actuator. The hand feel simulator includes a torque sensor, a hand feel simulator controller, a hand feel simulator motor, a hand feel simulator transmission mechanism, and a hand feel simulator angle sensor. The steering actuator includes a steering actuator controller, a steering actuator angle sensor, a steering actuator transmission mechanism, and a steering actuator motor.

[0036] In some specific implementations, the hand-feel simulator and the steering actuator exchange information via electrical signals. The hand-feel simulator controller, hand-feel simulator motor, hand-feel simulator transmission mechanism, and hand-feel simulator angle sensor are sequentially connected to form an internal closed loop; the steering actuator controller, steering actuator motor, steering actuator transmission mechanism, and steering actuator angle sensor are sequentially connected to form an internal closed loop.

[0037] In some specific implementations, the driver applies torque to the steering wheel to rotate the hand-feel simulator transmission mechanism, thereby generating the desired steering angle. This angle is measured by the hand-feel simulator angle sensor and output to the hand-feel simulator controller. The driver's hand torque needs to overcome the resistance torque of the hand-feel simulator motor, which is also measured by a torque sensor and sent to the hand-feel simulator controller to control the hand-feel simulator motor to generate torque. The steering actuator controller receives the driver's steering angle from the hand-feel simulator controller, compares it with the steering actuator angle sensor, and then controls the steering actuator motor to generate torque to move the steering actuator transmission mechanism to a position consistent with the driver's steering angle, thereby rotating the steering wheels.

[0038] Combination Figure 2 As shown, in order to achieve dynamic consistency between the steering actuator angle described above and the steering angle obtained by the hand-feel simulator (here, there is a following relationship between the actuator and the hand-feel simulator, or in other words, the purpose of this application is: the road surface actuator in steer-by-wire should follow the hand-feel simulator), a control method as shown in the schematic diagram of the invention needs to be designed, the process of which includes:

[0039] 1) Based on the torque sensor measurement value T of the hand-feel simulator sensor The desired linear feedforward motor torque of the steering actuator is calculated by a linear feedforward control module, wherein the linear feedforward control module is designed with a calibrable curve coefficient KL(x) based on the real-time changing torque sensor signal T. sensor The desired linear feedforward motor torque T of the steering actuator is calculated. LFW As shown in the following formula: T LFW =KL(x)T sensor ;

[0040] 2) The driver's steering angle θ is measured by the angle sensor of the hand-feel simulator. hwa And calculate the driver's turning speed. and acceleration Simultaneously considering the real-time steering actuator motor torque, the desired feedforward motor torque T of the steering actuator is calculated through the dynamic feedforward control module. FW The dynamic feedforward control module calculates the driver's steering speed. and acceleration Based on the actual output torque T of the motor act Calculate the desired feedforward motor torque T of the steering actuator FW : In the above formula, M rwa For the equivalent mass of the steering actuator, B rwa Let η be the equivalent damping of the steering actuator, η be the transmission efficiency of the steering actuator, and G be the transmission ratio of the steering actuator transmission mechanism.

[0041] 3) Based on the driver's steering angle θ hwa With steering actuator angle θ rwa The angle deviation is calculated by the PID feedback control module to obtain the desired feedback motor torque T of the steering actuator. FB The PID feedback control module measures the deviation (θ) between the driver's steering angle and the steering actuator angle. hwa -θ rwa ) Calculate and design a suitable k p k i k d Parameters are used to calculate the desired feedback motor torque T of the steering actuator. FB :

[0042] T FB =k p ×(θ hwa -θ rwa )+k i ×(θ hwa -θ rwa )+hd ×(θ hwa -θ rwa );

[0043] 4) The final desired steering actuator motor torque T sum For T LFW T FW t FB The sum of these three factors is then sent to the steering actuator motor for execution.

[0044] In summary, by adopting this system and control method, the driver applies torque to the steering wheel to rotate the hand-feel simulator transmission mechanism, thereby generating the desired steering angle. This angle is measured and output to the hand-feel simulator controller via the hand-feel simulator angle sensor. Simultaneously, the driver's hand torque needs to overcome the resistance torque of the hand-feel simulator motor, which is measured by a torque sensor and sent to the hand-feel simulator controller. Internal closed-loop torque control then controls the hand-feel simulator motor to generate torque. Meanwhile, the steering actuator controller receives the driver's steering angle from the hand-feel simulator controller and compares it with the steering actuator angle sensor. It then controls the steering actuator motor to generate torque, moving the steering actuator transmission mechanism to a position consistent with the driver's steering angle to rotate the steering wheels. Therefore, this invention, based on the dynamic consistency between the steering actuator angle and the steering angle obtained from the hand-feel simulator, achieves the goal of the road actuator in steer-by-wire following the hand-feel simulator. This improves the response characteristics of the steering actuator in the steer-by-wire system to the driver's input angle, enhances the accuracy of the response to dynamic driver input scenarios, and improves the lateral control precision of the vehicle.

[0045] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and apply the content of the present invention. However, this description should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A steer-by-wire system, comprising a steering system including a hand-feed simulator and a steering actuator, the hand-feed simulator including a torque sensor, a hand-feed simulator controller, a hand-feed simulator motor, a hand-feed simulator transmission mechanism, and a hand-feed simulator angle sensor; the steering actuator including a steering actuator controller, a steering actuator angle sensor, a steering actuator transmission mechanism, and a steering actuator motor, characterized in that: The angle of the steering actuator dynamically matches the steering angle obtained from the hand-feel simulator, wherein the torque of the steering actuator motor... for , , The sum of the three Based on the torque sensor measurement value of the hand feel simulator A calibrable curve coefficient can be designed using a linear feedforward control module. And based on the real-time changing torque sensor signal The desired linear feedforward motor torque of the steering actuator is calculated. For real-time steering actuator motor torque, the driver's steering angle is measured by the angle sensor on the hand feel simulator. And calculate the driver's turning speed. and acceleration Meanwhile, the real-time steering actuator motor torque is considered, and the desired feedforward motor torque of the steering actuator is calculated through the dynamic feedforward control module. To adjust according to the driver's steering angle With steering actuator angle The angle deviation is measured and controlled by a PID feedback control module to detect the deviation between the driver's steering angle and the steering actuator angle. Calculate and design a suitable , , The parameters are then used to calculate the desired feedback motor torque for the steering actuator.

2. The steer-by-wire system according to claim 1, characterized in that: The driver applies torque to the steering wheel to rotate the hand-feed simulator transmission mechanism, thereby generating the desired steering angle. The angle sensor of the hand-feed simulator measures and outputs the angle to the hand-feed simulator controller. The driver's hand torque needs to overcome the resistance torque of the hand-feed simulator motor, which is measured by the torque sensor and sent to the hand-feed simulator controller to control the hand-feed simulator motor to generate torque.

3. The steer-by-wire system according to claim 2, characterized in that: The hand-feel simulator controller, hand-feel simulator motor, hand-feel simulator transmission mechanism, and hand-feel simulator angle sensor are connected in sequence to form an internal closed loop.

4. The steer-by-wire system according to claim 1, characterized in that: The steering actuator controller receives the driver's steering angle from the hand-feel simulator controller, compares it with the steering actuator angle sensor, and then controls the steering actuator motor to generate torque to move the steering actuator transmission mechanism to a position consistent with the driver's steering angle so as to drive the steering wheel to rotate.

5. The steer-by-wire system according to claim 4, characterized in that: The steering actuator controller, steering actuator motor, steering actuator transmission mechanism, and steering actuator angle sensor are connected in sequence to form an internal closed loop.

6. The steer-by-wire system according to claim 1, characterized in that: The linear feedforward control module designs calibrable curve coefficients. Based on the real-time changing torque sensor signal The desired linear feedforward motor torque of the steering actuator is calculated. As shown in the following formula: 。 7. The steer-by-wire system according to claim 1, characterized in that: Steering actuator expects feedforward motor torque Simultaneously, the driver's steering angle is measured by the angle sensor of the hand-feel simulator. And calculate the driver's turning speed. and acceleration .

8. The steer-by-wire system according to claim 7, characterized in that: The dynamic feedforward control module calculates the driver's steering speed. and acceleration Based on the actual output torque of the motor Calculate the desired feedforward motor torque for the steering actuator : ， In the above formula, For the equivalent mass of the steering actuator, For the equivalent damping of the steering actuator, For the transmission efficiency of the steering actuator, This refers to the transmission ratio of the steering actuator drive mechanism.

9. The steer-by-wire system according to claim 7, characterized in that: Steering actuator expects to provide feedback motor torque : 。 10. An angle control method for a steer-by-wire system, characterized in that: The method employs the steer-by-wire system described in any one of claims 1 to 9, and the control process, in which the angle of the hand-feel simulator and the angle of the steering actuator are dynamically aligned, is as follows: 1) Based on the torque sensor measurement value of the hand-feel simulator The desired linear feedforward motor torque of the steering actuator is calculated by a linear feedforward control module, wherein the linear feedforward control module is designed with calibrable curve coefficients. Based on the real-time changing torque sensor signal The desired linear feedforward motor torque of the steering actuator is calculated. As shown in the following formula: ; 2) The dynamic feedforward control module calculates the driver's steering speed. and acceleration Based on the actual output torque of the motor Calculate the desired feedforward motor torque for the steering actuator : In the above formula, For the equivalent mass of the steering actuator, For the equivalent damping of the steering actuator, For the transmission efficiency of the steering actuator, The transmission ratio of the steering actuator drive mechanism; 3) Based on the driver's steering angle With steering actuator angle The angle deviation is calculated by the PID feedback control module to obtain the desired feedback motor torque of the steering actuator. The PID feedback control module measures the deviation between the driver's steering angle and the steering actuator angle. Calculate and design a suitable , , Parameters are used to calculate the desired feedback motor torque for the steering actuator. : ； 4) The final desired torque of the steering actuator motor for , , The sum of these three factors is then sent to the steering actuator motor for execution.

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