A method for electromagnetic radiation immunity test of a steer-by-wire system of a vehicle

Abstract

The application discloses a kind of electromagnetic radiation anti-interference test methods of automobile steer-by-wire system, comprising: 1) the vehicle to be measured is placed in electromagnetic radiation anti-interference test environment;2) install steering execution device to exert steering torque on the steering wheel of the vehicle to be measured and collect torque;3) install steering measuring device to collect the motion trajectory of P point of steering wheel;4) in the case where electromagnetic radiation interference is not applied and applied respectively, steering wheel rotation angle curve β (t) and γ (t) are calculated by P point motion trajectory;5) compare two curves, to determine whether the steering system meets electromagnetic radiation anti-interference test requirements accordingly.The present application solves the drawbacks that only steering wheel is detected in the current method without detecting the steering wheel, in the method, when measuring the steering wheel rotation angle, the steering axis centering operation is not needed, but the coordinate trajectory of P point is collected, and then the rotation angle curve is fitted, which is simple to operate, has small measurement error, good compatibility and high test efficiency.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic compatibility testing of automobile steering systems, and in particular to an electromagnetic radiation immunity testing method for a steering system of a steer-by-wire automobile. Background Art

[0002] Automotive steering systems are crucial for safe driving. With the continuous advancement of intelligent and electrified vehicles, steering systems are evolving from traditional mechanical transmission with electric power steering to steer-by-wire technology, with an increasing number of electronic components. Therefore, during the R&D phase, electromagnetic radiation immunity testing of automotive steering systems is essential to ensure proper operation in increasingly complex electromagnetic environments and to meet regulatory requirements.

[0003] The current method for testing electromagnetic radiation immunity in automotive steering systems involves placing the vehicle in a semi-anechoic chamber, installing an auxiliary steering device on the steering wheel, and applying torque to the steering wheel according to a pre-set torque curve, causing the steering wheel to rotate back and forth. The actual steering wheel angle curves are then collected when no electromagnetic radiation interference is applied and when electromagnetic radiation interference is applied. The difference in steering wheel angles before and after the electromagnetic interference is compared to determine whether the test requirements are met. This test method assumes a tight coupling relationship between the entire steering system, thus verifying the working status of the entire steering system by examining the working status of the steering wheel. This method is applicable to electromagnetic radiation immunity testing of traditional steering systems.

[0004] However, for vehicles with steer-by-wire systems, the mechanical connection between the steering wheel and the steering wheel is eliminated, replaced by electronic components such as the steering wheel angle sensor, wheel steering motor, and steering controller. This elimination of the mechanical connection decouples the steering wheel from the steering wheel. Therefore, the aforementioned test method is no longer able to fully identify any anomalies in the entire steering system during testing. For example, even if the test results show that the steering wheel operates normally before and after electromagnetic interference is applied, this does not prove that the steering controller can properly receive the steering wheel angle signal and control the steering motor to achieve normal wheel steering. Summary of the Invention

[0005] To this end, the main purpose of the present invention is to propose an electromagnetic radiation immunity test method for an automobile steering-by-wire system, which aims to solve the problem that the current automobile steering system electromagnetic radiation immunity test method cannot comprehensively and accurately detect various abnormal conditions that occur in the entire steering system during the test process when testing a car with a steering-by-wire system.

[0006] In order to solve the above problems, the technical solution adopted by the present invention is:

[0007] A method for electromagnetic radiation immunity testing of an automotive steer-by-wire system includes the following steps:

[0008] 1) Place the vehicle under test in an electromagnetic radiation immunity test environment;

[0009] 2) Install a steering actuator on the steering wheel of the vehicle under test to apply steering torque to the steering wheel of the vehicle under test and collect the actual output torque;

[0010] 3) Installing a steering measurement device on the steering wheel of the vehicle under test and defining a data collection point P, wherein the steering measurement device is used to collect the motion trajectory of point P;

[0011] 4) Without applying electromagnetic radiation interference to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and collects the actual output torque curve α′(t). At the same time, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve β(t) is calculated based on the motion trajectory of point P;

[0012] 5) When electromagnetic radiation interference of a set frequency and intensity is applied to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and the actual output torque curve α″(t) is collected. At the same time, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve γ(t) is calculated based on the motion trajectory of point P;

[0013] 6) Compare the changes in curve β(t) and curve γ(t) at each corresponding moment to determine whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements.

[0014] Furthermore: during the test, ensure that the actual output torque curves α′(t) and α″(t) are consistent with the defined torque curve α(t); and ensure that the starting time of the steering actuator applying the steering torque is exactly the same as the starting time of collecting the actual output torque curve and the starting time of the steering measurement device collecting the motion trajectory of point P.

[0015] Furthermore: the steering actuator includes a steering motor and a controller, and a torque sensor. The fixed end of the steering motor is fixedly connected to the floor or driver's seat of the vehicle under test, and the output end of the steering motor is fixedly connected to the steering wheel of the vehicle under test; the torque sensor is installed at the output end of the steering motor to measure the actual output torque.

[0016] Furthermore: the steering measurement device includes a three-coordinate measuring instrument and a connecting bracket. The three-coordinate measuring instrument is used to measure the motion trajectory of point P, and the connecting bracket is used to connect the steering wheel of the vehicle under test and the portable three-coordinate measuring instrument.

[0017] Furthermore: the connecting bracket is fixed to the steering wheel of the vehicle under test through nuts and stud bolts, the three-coordinate measuring machine is fixed to the connecting bracket through bolts, and the center point of the three-coordinate measuring machine probe is point P.

[0018] Furthermore: the data collection point P is any point that remains relatively stationary with respect to the steering wheel of the tested vehicle and maintains a certain distance from the steering axis of the steering wheel of the tested vehicle.

[0019] Furthermore, the method for calculating the steering wheel angle curves β(t) and γ(t) by the motion trajectory of point P is as follows:

[0020] 11) Define the measurement coordinate system A: Take the initial position of point P as the coordinate origin, the vertical upward direction as the positive z-axis, the front of the measured vehicle as the positive y-axis, and use the right-hand rule to determine the positive x-axis direction;

[0021] 12) The steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t). At the same time, the steering measurement device collects the coordinate trajectory of point P to obtain the curves x′(t) and y′(t) of the x and y coordinate values ​​of point P over time:

[0022] 13) For the curve x′(t), use the Z-score method to calculate the value of each coordinate point x′ of the curve x′(t). i Calculate the Z-score value:

[0023]

[0024] Where μ is all points x′ i The average value of all points x′ i The standard deviation of

[0025] Settings|Z i |threshold,|Z i The values ​​in the curve x′(t) that exceed the threshold are considered as outliers and are removed;

[0026] Use the moving average method to smooth the coordinate points after removing outliers to obtain the curve x(t):

[0027]

[0028] Where n is the window size for motion smoothing;

[0029] For the curve y′(t), the same logic is used to obtain:

[0030] 14) Then use the least squares method to fit the center coordinates O(h,k) of the trajectory of point P:

[0031] For each coordinate point (x i ,y i ), the error of this point is defined as:

[0032] e i (h,k,r)=(x i -h) 2 +(y i -k) 2 -r 2

[0033] Among them, r represents the radius of the motion trajectory of point P, h and k are the coordinates of the center of the motion trajectory of point P;

[0034] List the formula for the sum of squared errors of all points:

[0035]

[0036] Where m represents the total number of acquisition points involved in fitting;

[0037] Minimize E(h,k,r) and then find r, h and k;

[0038] 15) Then calculate each coordinate point (x i ,y i ) relative to the initial position of point P (x0, y0) i :

[0039]

[0040] The positive and negative directions of the steering wheel steering angle are determined by combining the coordinate system definition and the initial position of point P;

[0041] 16) Take each coordinate point (x i ,y i ) is the acquisition time as the horizontal axis, and the rotation angle β i As the vertical coordinate, draw the rotation angle curve β(t) of point P;

[0042] The rotation angle curve γ(t) is obtained in the same way.

[0043] Furthermore, the method for determining whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements is as follows:

[0044] Set a difference threshold;

[0045] Obtain the difference between the curve β(t) and the curve γ(t) at the corresponding time:

[0046] δ(t)=|β(t)-γ(t)|

[0047] If δ(t) does not exceed the set difference threshold, the steering system of the tested vehicle meets the electromagnetic radiation immunity test requirements;

[0048] If δ(t) exceeds the set difference threshold, the steering system of the vehicle under test does not meet the electromagnetic radiation immunity test requirements.

[0049] Furthermore: the electromagnetic radiation immunity test environment includes a semi-anechoic chamber, a signal generator, a power amplifier, and a transmitting antenna.

[0050] The testing method of the present invention has the following beneficial effects:

[0051] 1. A method for testing electromagnetic radiation immunity in automotive steering-by-wire systems is provided. By applying input torque to the steering wheel of the vehicle under test and measuring the actual steering angle at the steering wheel, the change in steering angle with and without electromagnetic radiation interference is compared to determine whether the entire steering system meets the electromagnetic radiation immunity test requirements. This method addresses the problem of current electromagnetic radiation immunity testing methods for automotive steering systems, which only test the steering system input (steering wheel) but not the steering system output (steering wheel). Consequently, for steering-by-wire systems with fully decoupled input and output, faults in the entire steering system cannot be fully identified, thus filling a technical gap in this testing field.

[0052] 2. In the test method of the present invention, the measurement point P can be defined as any point that is relatively stationary with the steering wheel of the vehicle being tested and maintains a certain distance from the steering axis of the steering wheel of the vehicle being tested. Strict measurement and positioning operations are not required. The definition of the measurement point P is relatively free, widely applicable, easy to implement, and highly executable.

[0053] 3. In the test method described in the present invention, when measuring the steering wheel angle, there is no need to perform complex operations such as steering axis alignment. Instead, the coordinate trajectory of point P is collected, and then the angle curves β(t) and γ(t) are obtained by fitting using a large number of coordinate points. The operation is simple and convenient, the measurement error is small, the compatibility is good, and the test efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is the test process described in the embodiment of the present invention;

[0055] Figure 2 This is the connection method of the steering measurement device according to the embodiment of the present invention;

[0056] Figure 3 are the coordinate trajectories x(t) and y(t) of point P after outlier removal and smoothing as described in the embodiment of the present invention;

[0057] Figure 4is the turning angle curve β(t) of the steering wheel according to the embodiment of the present invention (in the absence of electromagnetic interference).

[0058] Explanation of reference numerals: 1. Steering wheel of the vehicle under test; 2. Connecting bracket; 3. Portable three-coordinate measuring instrument; 4. Nut; 5. Stud bolt. DETAILED DESCRIPTION

[0059] The present invention is described in detail below with reference to the embodiments. Those skilled in the art should know that the following embodiments are not the only limitations on the technical solutions of the present invention, and any equivalent transformations or modifications made within the spirit of the technical solutions of the present invention should be deemed to fall within the scope of protection of the present invention.

[0060] like Figure 1 As shown, the electromagnetic radiation immunity test method of the automobile steer-by-wire system proposed in the present invention has the following specific process:

[0061] 1) Place the vehicle under test in an electromagnetic radiation immunity test environment;

[0062] 2) Installing a steering actuator on the steering wheel of the vehicle under test to apply a steering torque to the steering wheel of the vehicle under test and collecting the torque actually output by the steering actuator;

[0063] Define a torque curve α(t) to apply a steering torque to the steering wheel of the vehicle under test according to this curve;

[0064] 3) Installing a steering measurement device on the steering wheel of the vehicle under test and defining a data collection point P, wherein the steering measurement device is used to collect the motion trajectory of point P;

[0065] 4) Without applying electromagnetic radiation interference to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and the torque curve α′(t) actually output by the steering actuator is collected. At the same time, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve β(t) is calculated based on the motion trajectory of point P;

[0066] 5) applying electromagnetic radiation interference of a set frequency and intensity to the vehicle under test, causing the steering actuator to apply a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and collecting the torque curve α″(t) actually output by the steering actuator. Simultaneously, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve γ(t) is calculated based on the motion trajectory of point P;

[0067] 6) Check the torque curves α′(t) and α″(t) output by the steering actuator under the two operating conditions to ensure that they are consistent. Then, compare the changes in curves β(t) and γ(t) at the corresponding moments to determine whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements. If curves β(t) and γ(t) are the same, it means that the anti-interference ability is the best.

[0068] Furthermore, the electromagnetic radiation immunity test environment includes a 10m semi-anechoic chamber, a signal generator, a power amplifier, and a transmitting antenna. The semi-anechoic chamber is used to reduce electromagnetic background noise and prevent electromagnetic radiation interference emitted by the transmitting antenna from affecting or harming personnel and equipment outside the semi-anechoic chamber during testing. The signal generator, power amplifier, and transmitting antenna are used to generate and emit electromagnetic radiation interference of a set frequency and intensity.

[0069] Furthermore, the steering actuator includes a steering motor and controller, a torque sensor, and other components. The stationary portion of the steering actuator (the fixed end of the steering motor) is fixedly connected to stationary components such as the vehicle floor and driver's seat, while the moving portion (the output end of the steering motor) is fixedly connected to the steering wheel of the vehicle under test. The steering motor and controller are used to apply steering torque to the steering wheel of the vehicle under test based on the torque curve α(t). The torque sensor is installed at the output end of the steering motor to measure the actual output torque.

[0070] In the present invention, the torque curve α(t) is defined as a sine curve.

[0071] Furthermore, the steering measurement device includes a portable three-coordinate measuring instrument, a connecting bracket, etc. The portable three-coordinate measuring instrument is used to measure the motion trajectory of point P, and the connecting bracket is used to connect the steering wheel of the vehicle under test and the portable three-coordinate measuring instrument.

[0072] Depending on the connection method or bracket shape, the data collection point P can be any point that is relatively stationary with the steering wheel of the vehicle being tested and maintains a certain distance from the steering axis of the steering wheel of the vehicle being tested. To reduce measurement errors, point P should be farther away from the steering axis of the steering wheel being tested.

[0073] In this embodiment, the steering wheel of the vehicle being tested is connected to the portable three-dimensional coordinate measuring instrument by bolts, such as Figure 2 As shown, the connecting bracket 2 is fixed to the steering wheel 1 of the vehicle under test by a nut 4 and a stud bolt 5, and the portable three-dimensional coordinate measuring instrument 3 is fixed to the connecting bracket 2 by a bolt connection. At this time, the center point of the probe of the portable three-dimensional coordinate measuring instrument is point P.

[0074] Furthermore, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve β(t) and the steering wheel angle curve γ(t) are calculated based on the motion trajectory of point P. The specific method is as follows:

[0075] Define the measurement coordinate system A: The initial position of point P is used as the origin, the positive z-axis is vertically upward, the positive y-axis is directly in front of the vehicle being measured, and the positive x-axis is determined using the right-hand rule. Since the steering wheel does not move relative to the vertical direction, only the horizontal coordinates (x, y) of point P need to be considered.

[0076] In the absence of electromagnetic radiation interference applied to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and collects the actual output torque curve α′(t) of the steering actuator. At the same time, the coordinate trajectory of point P is collected by the steering measurement device to obtain curves x′(t) and y′(t) showing the x and y coordinate values ​​of point P changing with time, respectively.

[0077] Use the Z-score method to find and remove outliers on the curve x′(t), and for each coordinate point x′ of the curve x′(t) i Calculate the Z-score value:

[0078]

[0079] Where μ is all points x′ i The average value of all points x′ i The standard deviation of

[0080] Will | Z i |Values ​​exceeding the threshold are considered as outliers and are removed. For example, if the threshold is 3, |Z i Values ​​> 3 are considered outliers and are removed;

[0081] Use the moving average method to smooth the coordinate points after removing outliers to obtain the curve x(t):

[0082]

[0083] Wherein, n is the window size for motion smoothing processing, and in this embodiment, n=5;

[0084] Similarly, the curve y′(t) is smoothed and outliers are removed to obtain the curve y(t), as shown in Figure 3 Shown are the curves x(t) and y(t) after outliers are removed and smoothed;

[0085] Use the least squares method to fit the center coordinates O(h,k) of the trajectory of point P. For each coordinate point (x i ,y i ), the error of this point is defined as:

[0086] e i (h,k,r)=(x i -h) 2 +(y i -k) 2 -r 2

[0087] Among them, r represents the radius of the motion trajectory of point P, h and k are the coordinates of the center of the motion trajectory of point P;

[0088] In order to obtain the coordinates of the center of the P point trajectory as accurately as possible, the sum of square errors of all points should be minimized:

[0089]

[0090] Where m represents the total number of acquisition points involved in fitting;

[0091] Using the minimization method, the optimal results of r, h and k can be obtained;

[0092] Calculate the coordinates of each point (x i ,y i ) relative to the initial position of point P (x0, y0) i :

[0093]

[0094] The positive and negative directions of the steering wheel steering angle need to be determined in combination with the coordinate system definition and the initial position of point P. In this embodiment, Indicates the positive and negative direction of the steering wheel steering angle;

[0095] Each coordinate point (x i ,y i ) is the acquisition time as the horizontal axis, and the rotation angle β i As the vertical coordinate, the angle curve β(t) of point P is drawn, as shown in Figure 4 As shown, this is the turning angle curve of the steering wheel.

[0096] Similarly, the steering wheel angle curve γ(t) can be obtained when electromagnetic radiation interference of set frequency and intensity is applied to the vehicle under test.

[0097] Furthermore, during data collection, it is ensured that the starting time of the steering actuator outputting the steering torque to the steering wheel of the vehicle under test according to the defined torque curve is exactly the same as the starting time of collecting the actual output torque curve of the steering actuator and the starting time of collecting the motion trajectory of point P by the steering measurement device, that is, the starting time of the torque curve α′(t) and the torque curve α″(t) relative to the set torque curve α(t) is ensured to be consistent, and further, the starting time of the steering wheel output angle curve β(t) and the angle curve γ(t) relative to the set torque curve α(t) is ensured to be completely consistent. This is a prerequisite for comparing the angle values ​​of the angle curve β(t) and the angle curve γ(t) at corresponding moments.

[0098] Furthermore, the specific method for determining whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements by comparing the curve β(t) with the curve γ(t) is as follows:

[0099] Obtain the difference between the curve β(t) and the curve γ(t) at the corresponding time:

[0100] δ(t)=|β(t)-γ(t)|

[0101] A difference threshold is set, for example, 10% of the maximum steering wheel angle. If δ(t) does not exceed 10% of the maximum steering wheel angle of the tested vehicle, the steering system of the tested vehicle meets the electromagnetic radiation immunity test requirements and the test is passed. If δ(t) exceeds 10% of the maximum steering wheel angle of the tested vehicle, the steering system of the tested vehicle does not meet the electromagnetic radiation immunity test requirements and the test is failed.

[0102] The above are only preferred embodiments of the present invention, which are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; any modifications, equivalent replacements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for testing electromagnetic radiation immunity of an automobile steer-by-wire system, characterized in that: The processes involved are as follows: 1) Place the vehicle under test in an electromagnetic radiation immunity test environment; 2) Install a steering actuator on the steering wheel of the vehicle under test to apply steering torque to the steering wheel of the vehicle under test and collect the actual output torque; 3) Installing a steering measurement device on the steering wheel of the vehicle under test and defining a data collection point P, wherein the steering measurement device is used to collect the motion trajectory of point P; 4) Without applying electromagnetic radiation interference to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and collects the actual output torque curve α′(t). At the same time, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve β(t) is calculated based on the motion trajectory of point P; 5) When electromagnetic radiation interference of a set frequency and intensity is applied to the vehicle under test, the steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t), and the actual output torque curve α″(t) is collected. At the same time, the motion trajectory of point P is collected by the steering measurement device, and the steering wheel angle curve γ(t) is calculated based on the motion trajectory of point P; 6) Compare the changes in curve β(t) and curve γ(t) at each corresponding moment to determine whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements.

2. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, characterized in that: During testing, ensure that the actual output torque curves α′(t) and α″(t) are consistent with the defined torque curve α(t); And ensure that the starting time of the steering actuator applying the steering torque is exactly the same as the starting time of collecting the actual output torque curve and the starting time of the steering measurement device collecting the P point motion trajectory.

3. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, characterized in that: The steering actuator includes a steering motor and a controller, and a torque sensor. The fixed end of the steering motor is fixed to the floor or driver's seat of the vehicle under test, and the output end of the steering motor is fixed to the steering wheel of the vehicle under test. The torque sensor is installed at the output end of the steering motor to measure the actual output torque.

4. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, wherein: The steering measurement device includes a three-coordinate measuring instrument and a connecting bracket. The three-coordinate measuring instrument is used to measure the motion trajectory of point P, and the connecting bracket is used to connect the steering wheel of the measured vehicle and the portable three-coordinate measuring instrument.

5. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 4, characterized in that: The connecting bracket is fixed to the steering wheel of the vehicle under test by nuts and stud bolts, and the three-coordinate measuring machine is fixed to the connecting bracket by bolts. The center point of the probe of the three-coordinate measuring machine is point P.

6. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, 4 or 5, characterized in that: The data collection point P is any point that remains relatively stationary with respect to the steering wheel of the vehicle under test and maintains a certain distance from the steering axis of the steering wheel of the vehicle under test.

7. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to any one of claims 1 to 5, characterized in that: The method for calculating the steering wheel angle curves β(t) and γ(t) from the motion trajectory of point P is as follows: 11) Define the measurement coordinate system A: Take the initial position of point P as the coordinate origin, the vertical upward direction as the positive z-axis, the front of the measured vehicle as the positive y-axis, and use the right-hand rule to determine the positive x-axis direction; 12) The steering actuator applies a steering torque to the steering wheel of the vehicle under test according to the defined torque curve α(t). At the same time, the steering measurement device collects the coordinate trajectory of point P to obtain the curves x′(t) and y′(t) of the x and y coordinate values ​​of point P over time: 13) For the curve x′(t), use the Z-score method to calculate the value of each coordinate point x′ of the curve x′(t). i Calculate the Z-score value: Where μ is all points x′ i The average value of all points x′ i The standard deviation of Settings|Z i |threshold,|Z i The values ​​in the curve x′(t) that exceed the threshold are considered as outliers and are removed; Use the moving average method to smooth the coordinate points after removing outliers to obtain the curve x(t): Where n is the window size for motion smoothing; For the curve y′(t), the same logic is used to obtain: 14) Then use the least squares method to fit the center coordinates O(h,k) of the trajectory of point P: For each coordinate point (x i ,y i ), the error of this point is defined as: e i (h,k,r)=(x i -h) 2 +(y i -k) 2 -r 2 Among them, r represents the radius of the motion trajectory of point P, h and k are the coordinates of the center of the motion trajectory of point P; List the formula for the sum of squared errors of all points: Where m represents the total number of acquisition points involved in fitting; Minimize E(h,k,r) and then find r, h and k; 15) Then calculate each coordinate point (x i ,y i ) relative to the initial position of point P (x0, y0) i : The positive and negative directions of the steering wheel steering angle are determined by combining the coordinate system definition and the initial position of point P; 16) Take each coordinate point (x i ,y i ) is the acquisition time as the horizontal axis, and the rotation angle β i As the vertical coordinate, draw the rotation angle curve β(t) of point P; The rotation angle curve γ(t) is obtained in the same way.

8. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, wherein: The method for determining whether the steering system of the vehicle under test meets the electromagnetic radiation immunity test requirements is as follows: Set a difference threshold; Obtain the difference between the curve β(t) and the curve γ(t) at the corresponding time: δ(t)=|β(t)-γ(t)| If δ(t) does not exceed the set difference threshold, the steering system of the tested vehicle meets the electromagnetic radiation immunity test requirements; If δ(t) exceeds the set difference threshold, the steering system of the vehicle under test does not meet the electromagnetic radiation immunity test requirements.

9. The electromagnetic radiation immunity testing method for an automotive steer-by-wire system according to claim 1, wherein: The electromagnetic radiation immunity test environment includes a semi-anechoic chamber, a signal generator, a power amplifier, and a transmitting antenna.

Images