A redundancy check method for steering wheel angle signal of steer-by-wire

Abstract

The present invention relates to the technical field of wire-controlled steering, and in particular to a method for redundant verification of a steering wheel angle signal for wire-controlled steering. The method comprises the following steps: obtaining an initial angle signal; continuously sampling the steering wheel angle signal, and calculating a first steering wheel speed based on changes in the steering wheel angle; measuring the motor speed, calculating a second steering wheel speed through the motor speed, estimating the steering wheel angle, and obtaining an estimated angle value; judging whether the current steering wheel angle signal is correct based on the first steering wheel speed and the second steering wheel speed, and if correct, performing wire-controlled steering with the current steering wheel angle signal; otherwise, confirming that the current steering wheel angle signal is faulty, and performing wire-controlled steering with the estimated angle value. The present invention calculates a steering wheel angle signal through a motor position signal, increases steering wheel angle redundancy, and implements redundant verification of the steering wheel angle without increasing hardware costs.

Description

Technical Field

[0001] The present invention relates to the technical field of wire-controlled steering, and in particular to a redundancy verification method for a steering wheel angle signal. Background Art

[0002] The steer-by-wire product is mainly composed of angle sensors, power steering motors, steering controllers, speed reduction mechanisms, etc. The steering controller uses the control algorithm to calculate the power assistance required to control the steering wheel angle to track the target steering angle based on the angle sensor, the target steering angle of the autonomous driving controller, and the target steering angular velocity, and controls the torque output by the motor in response.

[0003] The magnetic field oriented control algorithm is used for motor control torque control, and the magnetic field oriented algorithm requires accurate motor phase current and motor rotor position signals. The current motor rotor position detection methods include rotary encoders, reluctance chips, incremental encoders, etc. In the wire control steering, the steering wheel angle needs to be backed up by wire control redundancy. However, the current design of the wire control steering machine only has one set of steering wheel angle sensors, and there is no way to achieve steering wheel angle redundancy backup and safety verification. Summary of the invention

[0004] The object of the present invention is to provide a redundant verification method for a steering wheel angle signal of a steer-by-wire system to solve the above technical problems;

[0005] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0006] A redundancy check method for a steering wheel angle signal of a steer-by-wire system, comprising:

[0007] Step S1, starting the steer-by-wire system, initializing the steering wheel angle signal to obtain an initial angle signal;

[0008] Step S2, actively applying a steering torque, continuously sampling the steering wheel angle signal, and calculating a first steering wheel speed based on a change in the steering wheel angle;

[0009] Step S3, measuring the motor speed, calculating the second steering wheel speed according to the motor speed, and estimating the steering wheel angle according to the initial angle signal and the motor rotor position signal to obtain an estimated angle value;

[0010] Step S4, judging whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed; if correct, performing steering-by-wire control with the current steering wheel angle signal; otherwise, confirming that the current steering wheel angle signal is faulty, performing steering-by-wire control with the estimated angle value.

[0011] Preferably, in step S2, the calculation formula of the first steering wheel speed S is:

[0012]

[0013] Among them, θ n Represents the steering wheel angle value at the nth moment, θ n-1 represents the steering wheel angle value at the n-1th moment, and t represents the interval between two angle values.

[0014] Preferably, in step S3, the calculation formula of the second steering wheel speed M is:

[0015]

[0016] Wherein, m represents the motor speed, and i represents the worm gear reduction ratio.

[0017] Preferably, in step S3, a redundant magnetoresistive chip is used to collect the current motor rotor position signal, and the signal type of the redundant magnetoresistive chip is a tunnel magnetoresistive signal.

[0018] Preferably, the redundant magnetoresistive chip uses a dual-path Wheatstone bridge to collect the relative angle of the magnetic ring fixed at the tail end of the motor rotor, the two Wheatstone bridges are powered separately and independently detect the relative position of the motor rotor, and the second steering wheel speed M includes the corresponding first-path speed value M1 and second-path speed value M2.

[0019] Preferably, in step S4, the method of judging whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed comprises:

[0020] Check whether the first steering wheel speed and the second steering wheel speed are in the same direction and check whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent. If both the direction and the speed values ​​are consistent, confirm whether the current steering wheel angle signal is correct; otherwise, confirm that the current steering wheel angle signal is faulty.

[0021] Preferably, in step S4, the method for checking whether the first steering wheel speed and the second steering wheel speed are in the same direction is:

[0022] The first steering wheel speed is multiplied by the second steering wheel speed. If the product is positive, it is determined that the first steering wheel speed and the second steering wheel speed are in the same direction; if the product is negative, it is determined that the first steering wheel speed and the second steering wheel speed are in opposite directions.

[0023] Preferably, in step S4, the method for checking whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent is:

[0024] Calculate the difference between the absolute values ​​of the first steering wheel speed and the second steering wheel speed. If the difference is less than a preset threshold, determine that the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent; otherwise, determine that the speed values ​​of the first steering wheel speed and the second steering wheel speed are inconsistent.

[0025] Preferably, in step S3, the estimated angle value θ 估算 The calculation formula is,

[0026]

[0027] Wherein, θ0 represents the initial angle signal, Indicates the motor rotor position at the n+1th moment, It represents the motor rotor position at the nth moment, and i represents the worm gear reduction ratio.

[0028] Preferably, the method further includes performing the steering-by-wire control with the estimated angle value when the communication between the steering wheel angle sensor for sampling the steering wheel angle signal and the controller for calculating the steering wheel rotation speed is interrupted.

[0029] Beneficial effects of the present invention: Due to the adoption of the above technical scheme, the present invention obtains the steering wheel angle signal through the motor position signal calculation, increases the redundancy of the steering wheel angle, and realizes the redundant verification of the steering wheel angle without increasing the hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the steps of a redundancy check method for a steering wheel angle signal of a steer-by-wire system according to an embodiment of the present invention;

[0031] Figure 2 The flowchart of the redundant checking method for the steering wheel angle signal of the steer-by-wire system in the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0035] A redundancy check method for steering wheel angle signals of steer-by-wire systems, such as Figure 1 , Figure 2 As shown, including

[0036] Step S1, starting the steer-by-wire system, initializing the steering wheel angle signal to obtain an initial angle signal;

[0037] Step S2, actively applying steering torque, continuously sampling the steering wheel angle signal, and calculating a first steering wheel speed based on a change in the steering wheel angle;

[0038] Step S3, measuring the motor speed, calculating the second steering wheel speed according to the motor speed, and estimating the steering wheel angle according to the initial angle signal and the motor rotor position signal to obtain an estimated angle value;

[0039] Step S4, judging whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed, if correct, performing steering-by-wire control with the current steering wheel angle signal; otherwise, confirming that the current steering wheel angle signal is faulty, performing steering-by-wire control with the estimated angle value.

[0040] Specifically, when the steer-by-wire system is started, the steering torque is actively applied, the motor rotor speed and the steering wheel angular velocity are measured, and the correctness of the motor rotor angle signal and the steering wheel angle signal are judged. When the motor angle signal is correct, the system passes the self-check.

[0041] In a preferred embodiment, in step S2, the calculation formula of the first steering wheel speed S is:

[0042]

[0043] Among them, θ n Represents the steering wheel angle value at the nth moment, θ n-1 represents the steering wheel angle value at the n-1th moment, and t represents the interval between two angle values.

[0044] In a preferred embodiment, in step S3, the calculation formula of the second steering wheel speed M is:

[0045]

[0046] Among them, m represents the motor speed and i represents the worm gear reduction ratio.

[0047] More specifically, calculating the steering wheel speed includes a first steering wheel speed S calculated by the steering wheel angle change and a second steering wheel speed M calculated by the motor speed;

[0048] The calculation formula of the first steering wheel speed S is:

[0049]

[0050] Among them, θ n Represents the steering wheel angle value at the nth moment, θ n-1 represents the steering wheel angle value at the n-1th moment, and t represents the interval between two angle values.

[0051] The calculation formula of the second steering wheel speed M is:

[0052]

[0053] Among them, m represents the motor speed and i represents the worm gear reduction ratio.

[0054] Further specifically, the present invention calculates the product of the first steering wheel speed S and the second steering wheel speed M and the difference between their absolute values ​​through the main control chip of the electric power steering (EPS) controller. When the product result is positive, it is determined that the two steering wheel speeds are in the same direction. When the product result is negative, it is determined that the two steering wheel speeds are in opposite directions. When the difference is less than 3 degrees per second, it is determined that the steering wheel speed calculations are consistent. Whether the current angle signal is correct is determined by judging the product and difference between the two.

[0055] In a preferred embodiment, in step S3, a redundant magnetoresistive chip is used to collect the current motor rotor position signal, and the signal type of the redundant magnetoresistive chip is a tunnel magnetoresistive signal.

[0056] Specifically, in the prior art, the input shaft position sensor of the wire-controlled steering machine adopts a redundant steering wheel angle sensor, which is only a sensor based on the SENT (Single Edge Nibble Transmission) protocol. The disadvantage is that the SENT protocol sensor has not yet been mass-produced, and most of the main controller chips currently in mass production do not have a SENT hardware decoding circuit;

[0057] The present invention adopts a tunnel magnetoresistance (TMR) sensor, which works based on the tunnel magnetoresistance effect. When the magnetic field changes, the resistance inside the sensor changes, and the change of the magnetic field strength and direction can be accurately detected by measuring the change of resistance. In the detection of the motor rotor position, by fixing the magnetic ring at the tail end of the motor rotor, the TMR sensor can detect the change of the magnetic field of the magnetic ring, thereby determining the relative position of the motor rotor. It has the advantages of high sensitivity, high precision, low power consumption, etc., and can accurately and quickly obtain the motor rotor position information.

[0058] The present invention adopts a motor position dual TMR sensor, and obtains a steering wheel angle signal by dividing the motor position signal by the reduction ratio. The steering wheel angle can be accurately calculated by using the TMR sensor to accurately detect the motor rotor position and combining the mechanical transmission relationship (reduction ratio) between the motor and the steering wheel.

[0059] Moreover, the TMR sensor does not need to add an additional decoding circuit like the SENT signal sensor, thus avoiding the problem of increased hardware cost due to the decoding circuit, so that the present invention realizes a redundancy solution for the steering wheel angle sensor without increasing the hardware cost.

[0060] In a preferred embodiment, the redundant magnetoresistive chip uses a dual-path Wheatstone bridge to collect the relative angle of the magnetic ring fixed at the tail end of the motor rotor. The two Wheatstone bridges are powered separately and independently detect the relative position of the motor rotor. The second steering wheel speed M includes the corresponding first-path speed value M1 and second-path speed value M2.

[0061] The current method for verifying the motor rotor position signal mainly uses a redundant reluctance chip. The TMR chip uses a dual-channel Wheatstone bridge to collect the relative angle of the magnetic ring fixed at the tail end of the motor rotor. The two Wheatstone bridges are powered separately and independently detect the relative position of the motor rotor.

[0062] Therefore, the steering wheel speed calculated by the motor is divided into a first speed value M1 and a second speed value M2. After the dual-path motor position signals are verified correctly, the second steering wheel speed M is calculated.

[0063] The present invention adopts a redundant magnetoresistive chip (TMR chip), whose dual-path Wheatstone bridges are respectively powered and independently detect the relative angle of the magnetic ring at the tail end of the motor rotor. The advantage is that the dual-path detection can be compared and verified with each other, thereby improving the reliability of the detection. If a fault or error occurs in one path, the other path can be used as a backup or for comparison and judgment to ensure the accuracy of the motor rotor position signal.

[0064] Due to dual-channel detection, the steering wheel speed calculated by the motor is divided into steering wheel speed M1 and steering wheel speed M2. Only when the dual-channel motor position signal is verified correctly, the final position steering wheel speed M used for judgment can be calculated. Ensure that the motor position signal used to calculate the steering wheel speed is accurate to avoid calculation deviation.

[0065] In a preferred embodiment, in step S4, the method for determining whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed includes:

[0066] Check whether the first steering wheel speed and the second steering wheel speed have the same direction and whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent. If both the direction and speed values ​​are consistent, confirm whether the current steering wheel angle signal is correct; otherwise, confirm that the current steering wheel angle signal is faulty.

[0067] In a preferred embodiment, in step S4, the method for checking whether the first steering wheel speed and the second steering wheel speed are in the same direction is:

[0068] The first steering wheel speed is multiplied by the second steering wheel speed. If the product is positive, it is determined that the first steering wheel speed and the second steering wheel speed are in the same direction; if the product is negative, it is determined that the first steering wheel speed and the second steering wheel speed are in opposite directions.

[0069] Specifically, the EPS controller main control chip calculates the product of the first steering wheel speed S (calculated based on the steering wheel angle change) and the second steering wheel speed M (calculated based on the motor speed). When the product result is positive, it means that the two steering wheel speeds are in the same direction; when the product result is negative, the two steering wheel speeds are in opposite directions.

[0070] In a preferred embodiment, in step S4, the method for checking whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent is:

[0071] The difference between the absolute values ​​of the first steering wheel speed and the second steering wheel speed is calculated. If the difference is less than a preset threshold, it is determined that the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent; otherwise, it is determined that the speed values ​​of the first steering wheel speed and the second steering wheel speed are inconsistent.

[0072] Specifically, while calculating the product of the first steering wheel speed S and the second steering wheel speed M, the EPS controller also calculates the difference in absolute values ​​between the first steering wheel speed S and the second steering wheel speed M. When the difference is less than 3 degrees per second, it determines that the steering wheel speed calculation is consistent.

[0073] The present invention combines the judgment of direction and size to more comprehensively and accurately evaluate whether the current angle signal is correct. If the judgment results of direction and size meet the conditions, the current angle signal is considered reliable; otherwise, there is a fault and the wire steering control is performed with the estimated angle value.

[0074] In a preferred embodiment, in step S3, the angle value θ is estimated 估算 The calculation formula is,

[0075]

[0076] Among them, θ0 represents the initial angle signal, Indicates the motor rotor position at the n+1th moment, It represents the motor rotor position at the nth moment, and i represents the worm gear reduction ratio.

[0077] Specifically, the steering wheel angle estimation formula of the present invention is:

[0078]

[0079] Among them, θ0 represents the initial angle signal, Indicates the motor rotor position at the n+1th moment, It represents the motor rotor position at the nth moment, and i represents the worm gear reduction ratio.

[0080] In the formula, It is the change of the motor position signal at adjacent moments (n+1 and n). By dividing the change by the worm gear reduction ratio i, we can get the value corresponding to the change in the steering wheel angle. Adding the initial steering wheel angle θ0, we can estimate the current steering wheel angle.

[0081] The steering controller calculates once every 1ms. The high-frequency calculation can track the changes in the steering wheel angle in a timely manner, thereby quickly providing a relatively accurate estimate when there is a problem with the actual steering wheel angle signal.

[0082] In a preferred embodiment, the method further includes performing a steer-by-wire control with an estimated angle value when the communication between a steering wheel angle sensor for sampling a steering wheel angle signal and a controller for calculating a steering wheel rotation speed is interrupted.

[0083] Specifically, the steering wheel angle sensor and the controller are connected through a wiring harness, and there is a situation where the wiring harness is short-circuited or open-circuited, resulting in the loss of the steering wheel angle signal when wire-controlled steering is performed. The steering wheel angle estimation signal estimated by the motor position signal is used for wire-controlled steering.

[0084] The steering wheel angle sensor of the present invention is connected to the controller through a wiring harness. The wiring harness may be affected by various factors during vehicle operation, such as vibration, wear, etc., resulting in short circuit or open circuit. When this happens, the steering wheel angle signal cannot be transmitted to the controller normally, causing the wire-controlled steering system to lose control basis.

[0085] At this time, the present invention uses the steering wheel angle estimation signal estimated by the motor position signal to perform wire-controlled steering, thereby continuing to maintain the steering function of the system, avoiding system out of control due to complete loss of the steering wheel angle signal, and reducing the risk of accidents.

[0086] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A redundancy check method for a steering wheel angle signal of a steer-by-wire system, characterized in that: include, Step S1, starting the steer-by-wire system, initializing the steering wheel angle signal to obtain an initial angle signal; Step S2, actively applying a steering torque, continuously sampling the steering wheel angle signal, and calculating a first steering wheel speed based on a change in the steering wheel angle; Step S3, measuring the motor speed, calculating the second steering wheel speed according to the motor speed, and estimating the steering wheel angle according to the initial angle signal and the motor rotor position signal to obtain an estimated angle value; Step S4, judging whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed, and if correct, performing wire-controlled steering with the current steering wheel angle signal; Otherwise, it is confirmed that the current steering wheel angle signal is faulty, and the wire-controlled steering is performed with the estimated angle value.

2. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 1, characterized in that: In step S2, the calculation formula of the first steering wheel speed S is: Among them, θ n Represents the steering wheel angle value at the nth moment, θ n-1 represents the steering wheel angle value at the n-1th moment, and t represents the interval between two angle values.

3. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 2, characterized in that: In step S3, the calculation formula of the second steering wheel speed M is: Wherein, m represents the motor speed, and i represents the worm gear reduction ratio.

4. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 1, characterized in that: In step S3, a redundant magnetoresistive chip is used to collect the current motor rotor position signal, and the signal type of the redundant magnetoresistive chip is a tunnel magnetoresistive signal.

5. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 4, characterized in that: The redundant magnetoresistive chip uses a dual-path Wheatstone bridge to collect the relative angle of the magnetic ring fixed at the rear end of the motor rotor. The two Wheatstone bridges are powered separately and independently detect the relative position of the motor rotor. The second steering wheel speed M includes the corresponding first-path speed value M1 and second-path speed value M2.

6. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 1, characterized in that: In step S4, the method of judging whether the current steering wheel angle signal is correct according to the first steering wheel speed and the second steering wheel speed includes: Check whether the first steering wheel speed and the second steering wheel speed are in the same direction and check whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent. If both the direction and the speed values ​​are consistent, confirm whether the current steering wheel angle signal is correct; otherwise, confirm that the current steering wheel angle signal is faulty.

7. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 6, characterized in that: In step S4, the method for checking whether the first steering wheel speed and the second steering wheel speed are in the same direction is: The first steering wheel speed is multiplied by the second steering wheel speed. If the product is positive, it is determined that the first steering wheel speed and the second steering wheel speed are in the same direction; if the product is negative, it is determined that the first steering wheel speed and the second steering wheel speed are in opposite directions.

8. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 6, characterized in that: In step S4, a method for checking whether the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent is: Calculate the difference between the absolute values ​​of the first steering wheel speed and the second steering wheel speed. If the difference is less than a preset threshold, determine that the speed values ​​of the first steering wheel speed and the second steering wheel speed are consistent; otherwise, determine that the speed values ​​of the first steering wheel speed and the second steering wheel speed are inconsistent.

9. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 1, characterized in that: In step S3, the estimated angle value θ 估算 The calculation formula is, Wherein, θ0 represents the initial angle signal, Indicates the motor rotor position at the n+1th moment, It represents the motor rotor position at the nth moment, and i represents the worm gear reduction ratio.

10. The method for redundant checking of steering wheel angle signals for steer-by-wire according to claim 1, characterized in that: The method further includes performing a steer-by-wire control using the estimated angle value when communication between a steering wheel angle sensor for sampling a steering wheel angle signal and a controller for calculating a steering wheel rotation speed is interrupted.

Images