A method, storage medium and system for calibrating vehicle equivalent wheel angle

Abstract

The present invention discloses a calibration method, storage medium and system for vehicle equivalent wheel angle. The method only needs to use a positioning sensor and a vehicle wheel angle sensor to calibrate and calculate the equivalent wheel angle of the vehicle steering. d , using the existing vehicle internal sensors, adopting a novel algorithm to overcome the equivalent wheel angle caused by the Ackermann nonlinear steering model, steering wheel toe angle / inclination angle / camber angle, sensor installation method, etc. when the wheeled vehicle is turning. d In order to solve the problem of large errors, the test shows that high-precision equivalent wheel angle calibration within 0.5° can be achieved in the entire steering range of the vehicle.

Description

Technical Field

[0001] The present invention relates to the field of autonomous driving, and more specifically, to a calibration method, storage medium and system for an equivalent wheel angle of a vehicle. Background Art

[0002] In the autonomous driving systems of four-wheel vehicles such as tractors, rice transplanters, wheeled harvesters, and plant protection machines, contact or non-contact wheel angle sensors (such as Hall sensors) are usually installed at the steering wheel to improve the accuracy of autonomous driving motion control. However, due to the serious nonlinearity of wheeled vehicle steering, which involves the influence of Ackermann nonlinear steering model, steering wheel toe angle / caster angle / camber angle, sensor installation method, etc., it is difficult for the wheel angle sensor to accurately measure the real-time vehicle equivalent wheel angle. In the autonomous driving motion control algorithm, the vehicle equivalent wheel angle is often d Serves as real-time feedback for steering control.

[0003] The existing technology usually uses a wheel angle sensor installed on the chassis and directly uses its angle value reading d WAS As the vehicle steering angle, to control the motion control system feedback. However, directly using d WAS Replace the equivalent wheel angle d This will usually result in a large error, especially when the vehicle is turning at a large angle, the error can even reach more than 10°, which will have a great impact on the performance of motion control and cause an error that cannot be ignored in the trajectory accuracy of autonomous driving curve tracking or turning. Summary of the invention

[0004] The present invention overcomes the shortcomings of the prior art in that the trajectory accuracy error is large in autonomous driving curve tracking or turning and U-turns, and provides a vehicle equivalent wheel angle calibration method, storage medium and system in the hope of solving the problems existing in the prior art.

[0005] In a first aspect, an embodiment of the present invention provides a method for calibrating an equivalent wheel angle of a vehicle, comprising:

[0006] A method for calibrating a vehicle equivalent wheel angle comprises the following steps:

[0007] S1 is on the plane, with fixed initial vehicle wheel angle d WAS (1) Control the vehicle to move forward for a period of time t ;

[0008] S2 obtains the vehicle moving distance Δ s and the heading angle change Δ h ;

[0009] S3 According to the formula Calculate the kinematic equivalent wheel angle;

[0010] In the formula, d is the kinematic equivalent wheel angle, L is the vehicle wheelbase;

[0011] Get the fixed initial vehicle wheel angle d WAS (1) and the corresponding equivalent wheel angle d (1), that is ( d WAS (1), d (1)).

[0012] Get the heading angle change Δ h It can be obtained by recording the heading angle of the first and last points of the vehicle;

[0013] In the obtained moving distance Δ s and the heading angle change Δ h Afterwards, by , the driving radius can be calculated R The principle can be found in the attached Figure 1 ;

[0014] according to and , it can be concluded that ;

[0015] in, d is the kinematic equivalent wheel angle, L is the vehicle wheelbase;

[0016] It can be seen that d With Δ h There is a strong coupling relationship, Δ h The observability of d Also known as observable quantity: Δ s The error is generally within 2cm (positioning accuracy), Δ s is in the denominator position, so Δ s Error pair d The impact is small.

[0017] L is the wheelbase, which is a fixed value and can be considered to be error-free.

[0018] The following example illustrates the error range of the technical solution of this application. When driving at a speed of 0.5 m / s for 5 seconds, Δ s About 2.5m, coefficient L / Δ s It is about 0.5.

[0019] When the heading change Δ h When the absolute value is large, such as 10°, the heading angle error 0.2° / 1m baseline is very small compared to 10°. h Error pair d The impact is small;

[0020] When the heading change Δ h When the absolute value is small, such as 0.3°, the heading angle error is 0.2° / 1m, which is equivalent to 0.3°. The actual heading change is submerged in its own error, but the actual heading angle is also small at this time. d is also small, so this method achieves d Precise measurement of

[0021] A further technical solution is that the vehicle is obtained t Distance traveled in time Δ s The specific steps include:

[0022] Record vehicle in t In time n Positioning data of points ( x i , y i );

[0023] .

[0024] The positioning data ( x i , y i ) can use the real-time position of the rear axle center.

[0025] A further technical solution is to measure a group of ( d WAS (1), d (1) After that, do the following:

[0026] Changing the vehicle's wheel angle d WAS ( i ), control the vehicle to maintain the vehicle wheel angle d WAS ( i ) Move forward for a period of time t ;

[0027] Execute S2-S3 to calculate the fixed vehicle wheel angle d WAS ( i ) and the corresponding equivalent wheel angle d ( i ).

[0028] Since different vehicle wheel angles correspond to different equivalent wheel angles, by changing the vehicle wheel angle and driving and repeating the above steps, the equivalent wheel angle results corresponding to other vehicle wheel angles can be obtained.

[0029] A further technical solution is that the initial vehicle wheel angle d WAS (1) The left or right limit position of the vehicle d WASmin ;

[0030] After S1, perform the following steps:

[0031] S11 controls the vehicle direction from d WASmin limit position, turn to the limit position in the opposite direction until it reaches the limit position in the opposite direction d WASmax ;

[0032] S12 divides the driving distance into m , and get the wheel angle of each vehicle segment d WAS ( i );

[0033] ,in i = 1~ m ;

[0034] Specifically, S2 is to obtain m The vehicle travel distance per trip Δ s and the heading angle change Δ h ;

[0035] Specifically, S3 is: calculate m The wheel angle of the vehicle in each trip d WAS ( i ) corresponds to the equivalent wheel angle d (i).

[0036] In order to cover every vehicle wheel angle d WAS ( i ) corresponds to the equivalent wheel angle d (i) Change the vehicle direction from d WASmin The limit position turns to the opposite limit position d WASmax , and collect vehicle wheel angles at different road sections d WAS ( i ) corresponds to the equivalent wheel angle d (i) Each vehicle wheel angle can be realized d WAS ( i ) corresponds to the equivalent wheel angle d Calculation of (i).

[0037] In from d WASmin The limit position turns to the opposite limit position d WASmax The vehicle path can refer to the attached Figure 2 It should be noted that the attached Figure 2 It only represents one possible path for the vehicle wheel angle to change, that is, the 13 paths where the vehicle wheel angle changes from the left limit to the right limit. In the actual motion acquisition process, each road segment can run at a different angle, as long as the vehicle wheel angle covers the entire path. d WASmin limit position to the reverse limit position d WASmax That's it.

[0038] A further technical solution is to divide the vehicle direction angle interval into m ranges, in each range, select an angle to execute S1-S3;

[0039] In getting m Wheel angle of each vehicle in the journey d WAS ( i ) corresponds to the equivalent wheel angle d After (i), perform the following steps:

[0040] Will m Group road section vehicle wheel angle d WAS ( i ) corresponds to the equivalent wheel angle d (i) Perform polynomial fitting to obtain the vehicle wheel angle d WAS ( i ) and equivalent wheel angle d (i) High-precision correspondence δ=f ( d WAS ).

[0041] If you want to get a more accurate vehicle wheel angle d WAS ( i ) corresponds to the equivalent wheel angle d (i) To obtain the polynomial fitting result, we need to have corresponding data points in different ranges. By dividing the vehicle direction angle interval into mA range is defined so that each vehicle angle interval has a data point.

[0042] A further technical solution is that the vehicle wheel angle value is obtained by the wheel angle sensor voltage value V WAS Sure.

[0043] Wheel angle sensor voltage value V WAS and vehicle wheel angle d WAS There is a clear correspondence, and the sensor voltage value V WAS It is more convenient to measure using the sensor voltage value V WAS It is convenient to determine the vehicle wheel angle value.

[0044] In a second aspect, an embodiment of the present invention provides a storage medium comprising computer executable instructions, which, when executed by a computer processor, are used to execute a vehicle equivalent wheel angle calibration method as described above.

[0045] In a third aspect, an embodiment of the present invention provides a vehicle equivalent wheel angle calibration system, comprising:

[0046] Processor, positioning sensor, vehicle wheel angle sensor;

[0047] The processor is used to obtain the vehicle heading angle data and vehicle position data collected by the positioning sensor, and the vehicle wheel angle data collected by the vehicle wheel angle sensor;

[0048] The processor is used to calculate the heading angle change Δ according to the vehicle heading angle data and position data h and vehicles in t Distance traveled in time Δ s ;

[0049] The processor is used to calculate the angle change Δ h , moving distance Δ s , Vehicle wheelbase L and vehicle wheel angle d WAS , calculate the vehicle wheel angle d WAS Equivalent wheel angle of motion d .

[0050] The positioning sensor is used to obtain vehicle heading angle and vehicle position data;

[0051] The vehicle wheel angle sensor is used to collect vehicle wheel angle data.

[0052] A further technical solution is that the processor is also used to obtain the vehicle direction from d WASmin limit position, turn to the limit position in the opposite direction until it reaches the limit position in the opposite direction d WASmax The location data of the vehicle collected by the positioning sensor;

[0053] According to the vehicle's location data, the driving distance is divided into m Get the data collected by the vehicle wheel angle sensor m Vehicle wheel angle for each trip d WAS ;

[0054] Calculate the wheel angle of each vehicle segment d WAS ( i ) corresponds to the equivalent wheel angle d (i), that is ( d WAS (i), d (i)).

[0055] A further technical solution is that the processor is also used to m Group segment data ( d WAS (i), d (i) Perform polynomial fitting to obtain the vehicle wheel angle d WAS ( i ) and equivalent wheel angle d (i) High-precision correspondence δ=f ( d WAS ).

[0056] Compared with the prior art, the present invention has at least the following beneficial effects: the method only needs to use the positioning sensor and the vehicle wheel angle sensor to calculate the equivalent wheel angle of the vehicle steering. d It utilizes the existing sensors inside the vehicle, adopts a relatively simple structure and a novel algorithm to overcome the equivalent wheel angle caused by the Ackermann nonlinear steering model, steering wheel toe angle / inclination angle / camber angle, sensor installation method, etc. when the wheeled vehicle is turning. d In order to solve the problem of large errors, the test shows that high-precision equivalent wheel angle calibration within 0.5° can be achieved in the entire steering range of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 Calculate the schematic diagram for a single arc route;

[0058] Figure 2 The path from the vehicle wheel angle covering the limit position to the reverse limit position;

[0059] Figure 3 This is a schematic diagram of the fitting relationship of Example 1;

[0060] Figure 4 This is a schematic diagram of the fitting relationship of Example 2. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] Embodiment 1

[0063] A method for calibrating a vehicle equivalent wheel angle comprises the following steps:

[0064] S1 is on the plane, with fixed initial vehicle wheel angle d WAS (1) Control the vehicle to move forward for a period of time t ;

[0065] In this embodiment, the vehicle wheel angle value d WAS The voltage value of the wheel angle sensor V WAS Sure.

[0066] S2 obtains the moving distance of the vehicle Δ s and the heading angle change Δ h ;

[0067] S21 obtains the vehicle t Distance traveled in time Δ s The specific steps include:

[0068] Record vehicle in t In time n Positioning data of each point ( x i , y i );

[0069] .

[0070] Get the heading angle change Δ h It can be obtained by recording the heading angle of the first and last points of the vehicle;

[0071] It should be noted that the heading angle change Δ h It can be obtained in many ways. For example, the heading angle of a dual-antenna system is calculated by directly reading the NMEA-HEADING message.

[0072]

[0073] Among them, heading(n) is the heading angle of the end point, and heading(l) is the heading angle of the first point;

[0074] For a single antenna system, the heading angle is obtained from the yaw value of the inertial navigation unit;

[0075]

[0076] Among them, yaw(n) is the heading angle of the final point, and yaw (l) is the heading angle of the first point;

[0077] In this embodiment, the dual antenna system is used to directly read the NMEA-HEADING message for calculation.

[0078] S3 According to the formula Calculate the kinematic equivalent wheel angle;

[0079] In the formula, d is the kinematic equivalent wheel angle, L is the vehicle wheelbase;

[0080] The specific steps are as follows: s and the heading angle change Δ h back, ,Depend on Figure 1 It can be seen that ;

[0081] , the driving radius can be calculated R ;

[0082] according to and , it can be concluded that ;

[0083] in, d is the kinematic equivalent wheel angle, L is the vehicle wheelbase;

[0084] Get the sensor voltage value V WAS The corresponding equivalent wheel angle d ,Right now( V WAS , d ).

[0085] S4 Change vehicle wheel angle d WAS , control the vehicle to maintain the vehicle wheel angle d WAS Move forward for a period of time t ;

[0086] Execute S2-S3 to calculate the sensor voltage value when the vehicle wheel angle is fixed V WAS , and the corresponding equivalent wheel angle d .

[0087] In this embodiment, a total of 12 changes are made, 13 sets of data are measured, and 13 sets of equivalent wheel angles are obtained after calculating the 13 sets of data. d , the data is as follows:

[0088]

[0089] S5: m Group road section vehicle wheel angle d WAS ( i ) corresponds to the equivalent wheel angle d (i) Perform polynomial fitting to obtain the vehicle wheel angle d WAS ( i ) and the high-precision correspondence between the equivalent wheel angle δ(i) δ=f(δ WAS ) .

[0090] In this embodiment, a fifth-order polynomial is used for data fitting, and the obtained fitting relationship is:

[0091]

[0092] like Figure 3 As shown in the figure, the calibration data and the fitting curve are basically consistent with each other, and the error is small.

[0093] Embodiment 2

[0094] A method for calibrating an equivalent wheel angle of a vehicle is different from the first embodiment in that:

[0095] In this embodiment, the vehicle wheel angle value in S1 d WAS Using the steering wheel angle reading d steering ;

[0096] By changing the steering wheel angle d ( d steering ), 35 sets of data were measured, and 35 sets of equivalent wheel angles were obtained after calculating the 35 sets of data. d , the data is as follows:

[0097]

[0098] The above data were fitted with a fifth-order polynomial, and the fitting relationship was:

[0099]

[0100] in e = d steering .

[0101] like Figure 4 As shown in the figure, the calibration data and the fitting curve are basically consistent with each other, and the error is small.

[0102] Embodiment 3

[0103] A storage medium containing computer executable instructions, wherein the computer executable instructions are used to perform a vehicle equivalent wheel angle calibration method as described above when executed by a computer processor, the method comprising:

[0104] S1 is on the plane, with fixed initial vehicle wheel angle d WAS (1) Control the vehicle to move forward for a period of time t ;

[0105] S2 obtains the moving distance Δ of the vehicle in time t s and the heading angle change Δ h ;

[0106] S3 According to the formula Calculate the kinematic equivalent wheel angle.

[0107] Of course, the storage medium containing computer executable instructions provided in an embodiment of the present invention is not limited to the method operations described above, and the computer executable instructions can also execute related operations in the vehicle equivalent wheel angle calibration method provided in any embodiment of the present invention.

[0108] Embodiment 4

[0109] A vehicle equivalent wheel angle calibration system, comprising:

[0110] Processor, positioning sensor, vehicle wheel angle sensor;

[0111] The processor can be configured on the vehicle or outside the vehicle, and the optional one is ECU (Electronic Control Unit), also known as the vehicle computer. The processor is connected to the positioning sensor and the vehicle wheel angle sensor for communication. The processor is used to obtain the vehicle heading angle data and vehicle position data collected by the positioning sensor, and the vehicle wheel angle data collected by the vehicle wheel angle sensor;

[0112] The processor is used to calculate the heading angle change Δ according to the vehicle's position data h and vehicles in tDistance traveled in time Δ s ;

[0113] The processor is used to calculate the angle change Δ h , moving distance Δ s , vehicle wheelbase L and vehicle wheel angle d WAS , calculate the vehicle wheel angle d WAS Equivalent wheel angle of motion d .

[0114] The positioning sensor is used to obtain vehicle heading angle and vehicle position data, and the positioning sensor can adopt a dual-antenna combined navigation system or a single-antenna combined navigation system.

[0115] The vehicle wheel angle sensor is used to collect vehicle wheel angle data. The vehicle wheel angle sensor can be a wheel angle sensor that can read wheel angle readings, or a wheel angle sensor that reads a wheel angle sensor voltage value.

[0116] In a preferred embodiment, the processor is further configured to obtain the vehicle direction from d WASmin limit position, turn to the limit position in the opposite direction until it reaches the limit position in the opposite direction d WASmax The location data of the vehicle collected by the positioning sensor;

[0117] According to the vehicle's location data, the driving distance is divided into m Get the data collected by the vehicle wheel angle sensor m Vehicle wheel angle for each trip d WAS ;

[0118] Calculate the wheel angle of each vehicle segment d WAS ( i ) corresponds to the equivalent wheel angle d (i), that is ( d WAS (i), d (i)).

[0119] In a preferred embodiment, the processor is further configured to: m Group segment data ( d WAS (i), d (i) Perform polynomial fitting to obtain the vehicle wheel angle d WAS ( i ) and equivalent wheel angle d (i) High-precision correspondence δ=f ( dWAS ).

[0120] Although the present invention is described herein with reference to the illustrative embodiments of the present invention, it should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in the present application. More specifically, within the scope disclosed in the present application, multiple variations and improvements can be made to the components and / or layout of the subject combination layout. In addition to the variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A method for calibrating a vehicle equivalent wheel angle, characterized in that: The following steps are involved: S1 is on the plane, with fixed initial vehicle wheel angle δ WAS (1) Control the vehicle to move forward for a period of time t ; The initial vehicle wheel angle δ WAS (1) is the left limit position of the vehicle δ WASmax or right limit δ WASmin ; S11 controls the vehicle direction from δ WASmin limit position, turn to the limit position in the opposite direction until it reaches the limit position in the opposite direction δ WASmax ; S12 divides the driving distance into m , and get the wheel angle of each vehicle segment δ WAS ( i ); S2 obtains the vehicle t Within time m The vehicle travel distance per trip Δ s and the heading angle change Δ h ; S3 According to the formula calculate m The wheel angle of the vehicle in each trip δ WAS ( i ) corresponds to the equivalent wheel angle δ (i); where δ is the kinematic equivalent wheel angle, L is the vehicle wheelbase; Get the vehicle wheel angle for each trip δ WAS ( i ) corresponds to the equivalent wheel angle δ (i).

2. A method for calibrating a vehicle equivalent wheel angle according to claim 1, characterized in that: The vehicle is obtained in t Distance traveled in time Δ s The specific steps include: Record vehicle in t In time n Positioning data of each point ( x i , y i ); 。 3. The method for calibrating the equivalent wheel angle of a vehicle according to claim 1, characterized in that: Before executing S1, the vehicle direction angle interval is divided into m ranges, in each range, select an angle to execute S1-S3; In getting m Wheel angle of each vehicle in the journey δ WAS ( i ) corresponds to the equivalent wheel angle δ After (i), perform the following steps: Will m Group road section vehicle wheel angle δ WAS ( i ) corresponds to the equivalent wheel angle δ (i) Perform polynomial fitting to obtain the vehicle wheel angle δ WAS ( i ) and equivalent wheel angle δ (i) High-precision correspondence δ = f ( δ WAS ).

4. A method for calibrating a vehicle equivalent wheel angle according to any one of claims 1 to 3, characterized in that: The vehicle wheel angle value is determined by the wheel angle sensor voltage value V WAS Sure.

5. A storage medium containing computer executable instructions, characterized in that: The computer executable instructions are used to execute a vehicle equivalent wheel angle calibration method as described in any one of claims 1 to 3 when executed by a computer processor.

6. A vehicle equivalent wheel angle calibration system using the calibration method according to any one of claims 1 to 4, characterized in that: include: Processor, positioning sensor, vehicle wheel angle sensor; The processor is used to obtain the vehicle position data collected by the positioning sensor and the vehicle wheel angle sensor. t Vehicle wheel angle in time δ WAS ; The processor is used to calculate the heading angle change Δ according to the vehicle's position data h and vehicles in t Distance traveled in time Δ s ; The processor is used to calculate the angle change Δ h , moving distance Δ s , vehicle wheelbase L and vehicle wheel angle δ WAS , calculate the vehicle wheel angle δ WAS Equivalent wheel angle of motion δ .

7. A vehicle equivalent wheel angle calibration system as claimed in claim 6, characterized in that: The processor is also used to obtain the vehicle direction from δ WASmin limit position, turn to the limit position in the opposite direction until it reaches the limit position in the opposite direction δ WASmax The location data of the vehicle collected by the positioning sensor; According to the vehicle's location data, the driving distance is divided into m Get the data collected by the vehicle wheel angle sensor m Wheel angle of vehicle for each trip δ WAS ; Calculate the wheel angle of each vehicle segment δ WAS ( i ) corresponds to the equivalent wheel angle δ (i), that is ( δ WAS (i), δ (i)).

8. A vehicle equivalent wheel angle calibration system as claimed in claim 7, characterized in that: The processor is also used to m Group segment data ( δ WAS (i), δ (i) Perform polynomial fitting to obtain the vehicle wheel angle δ WAS ( i ) and equivalent wheel angle δ (i) High-precision correspondence δ = f ( δ WAS ).

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