A method and device for calculating and calibrating the rotation angle of the articulated shaft of an articulated vehicle

Abstract

The present invention provides a method and device for calculating and calibrating the turning angle of an articulated shaft of an articulated vehicle. This technical solution first creates a motion model of the articulated vehicle, explains the relationship between the turning radius of the articulated vehicle and the turning angle of the articulated shaft, and on this basis constructs an accurate calculation method for the value of the turning angle θ of the articulated shaft. This method first measures the distance L between the articulated shaft and the front axle f , measures the distance L between the articulated shaft and the rear axle r , and successively measures the turning radius R values at predetermined angles; furthermore, by the Newton iteration method: f(θ) = R*tanθ - (L f + L r / cosθ), θ = θ0 - f(θ0) / f’(θ0); the accurate value of the turning angle θ corresponding to the turning radius R value is calculated. At the same time, the present invention also provides a device for executing this method and an unmanned articulated vehicle. The motion model of the present invention is highly consistent with the actual state of the operation of the articulated vehicle, and the calculation result is accurate and the algorithm efficiency is high, which helps the unmanned driving algorithm to better control the articulated vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned vehicle control, and further to steering calibration of an unmanned articulated vehicle, and in particular to a method and device for calculating and calibrating the rotation angle of an articulated shaft of an articulated vehicle. Background Art

[0002] When a human driver is driving an articulated vehicle, the driver can observe the road conditions in real time to determine how to control the steering wheel so that the articulated vehicle can avoid obstacles or drive on a curve. When an unmanned driving system is controlling an articulated vehicle, it is necessary to obtain the relationship between the articulation axis angle and the vehicle turning radius to assist the unmanned driving system in completing path planning and direction control.

[0003] The traditional method for calculating the relationship between the turning radius R and the wheel end turning angle θ of a vehicle treats the vehicle as a rigid body. It only needs to know the vehicle wheelbase L and the current angle turning radius R value to calculate the corresponding vehicle end turning angle θ value by the formula sinθ=L / R (e.g. Figure 1 However, when an articulated vehicle is turning, it is not a rigid body motion. Therefore, the traditional Ackerman steering vehicle turning radius and turning angle calculation method cannot calculate the turning radius and turning angle of the articulated vehicle. In this case, how to establish the motion model of the articulated vehicle and then clarify the relationship between the turning radius and the turning angle of the articulated axis is expected to achieve the steering calibration of the articulated vehicle. Summary of the invention

[0004] The present invention aims to address the technical defects of the prior art and provide a method and device for calculating and calibrating the articulated shaft angle of an articulated vehicle, so as to solve the technical problem that the calculation method of the relationship between the turning radius R and the wheel end angle θ of a traditional vehicle is not suitable for articulated vehicles.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A method for calculating and calibrating the rotation angle of an articulated shaft of an articulated vehicle, comprising: measuring the distance L between the articulated shaft and the front axle f , measure the distance L between the articulated axis and the rear axle r , and measure the turning radius R value at each predetermined angle in turn; calculate the exact value of the hinge axis angle θ corresponding to the turning radius R value by the following formula: f(θ)=R*tanθ-(L f +L r / cosθ), θ=θ0-f(θ0) / f'(θ0).

[0007] Preferably, the method comprises the following steps:

[0008] 1) The steering calibration module sends a steering calibration start signal and a predetermined steering wheel steering angle to be calibrated to the unmanned driving system;

[0009] 2) The unmanned driving system sets the steering angle of the steering wheel of the unmanned articulated vehicle to the steering angle of the steering wheel that needs to be calibrated and controls the unmanned articulated vehicle to travel at a preset driving speed;

[0010] 3) The unmanned driving system calculates the vehicle turning radius R at the current steering angle based on the positioning data;

[0011] 4) The vehicle-mounted articulated shaft angle sensor feeds back an angle reference value θ0;

[0012] 5) The steering calibration module reads and stores the angle reference value θ0 fed back by the articulated shaft angle sensor and the vehicle turning radius R at the current steering angle;

[0013] 6) The steering calibration module determines whether there is a predetermined steering wheel steering angle to be calibrated that has not been executed, and if so, repeats steps 1)-5), and if not, the unmanned driving system controls the vehicle to stop;

[0014] 7) The steering calibration module calculates the precise value θ of the articulated shaft angle corresponding to each turning radius R in each stored set of data to be calibrated according to the relationship between the turning radius R value of the articulated vehicle and the articulated shaft angle θ and the Newton iteration method;

[0015] 8) The steering calibration module fits and outputs the corresponding relationship between the turning radius R and the articulation axis angle θ to complete the steering parameter calibration of the unmanned articulated vehicle.

[0016] On the basis of the above technical scheme, the present invention further provides a device for executing the above method, which includes an unmanned driving system that can control the turning and walking of an articulated vehicle, an articulated shaft angle sensor, and a steering calibration module; the unmanned driving system, the articulated shaft angle sensor, and the steering calibration module are interconnected for communication.

[0017] Preferably, the device also includes a chassis domain controller; the unmanned driving system, the articulated shaft angle sensor, the steering calibration module, and the chassis domain controller are communicatively connected to each other.

[0018] On the basis of the above technical solution, the present invention further provides an unmanned articulated vehicle equipped with the above device.

[0019] The present invention provides a method and device for calculating and calibrating the rotation angle of the articulated shaft of an articulated vehicle. The technical solution first creates a motion model of the articulated vehicle, explains the relationship between the turning radius of the articulated vehicle and the rotation angle of the articulated shaft, and constructs an accurate calculation method for the rotation angle θ of the articulated shaft based on this. The method first measures the distance L between the articulated shaft and the front axle. f , measure the distance L between the articulated axis and the rear axle r, and measure the turning radius R value at each predetermined angle in turn; then use Newton iteration method: f(θ)=R*tanθ-(L f +L r / cosθ), θ=θ0-f(θ0) / f'(θ0); calculate the precise value of the articulation axis rotation angle θ corresponding to the turning radius R. At the same time, the present invention also provides a device for executing the method and an unmanned articulated vehicle. The motion model of the present invention is highly consistent with the actual state of the articulated vehicle, and the calculation result is accurate and the algorithm is efficient, which helps the unmanned driving algorithm to better control the articulated vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the traditional Ackerman steering vehicle motion model.

[0021] Figure 2 It is a schematic diagram of the articulated vehicle motion model established by the present invention.

[0022] Figure 3 It is a communication relationship diagram of each module in the device of the present invention.

[0023] Figure 4 It is a function list of the steering calibration module in the device of the present invention.

[0024] Figure 5 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention will be described in detail below. In order to avoid too much unnecessary details, the well-known structures or functions will not be described in detail in the following examples. The approximate language used in the following examples can be used for quantitative expression, indicating that the quantity can be allowed to have a certain change without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following examples have the same meaning as those generally understood by those skilled in the art to which the present invention belongs.

[0026] Establish an articulated vehicle motion model such as Figure 2 , measure the distance L between the articulated axis and the front axle f , measure the distance L between the articulated axis and the rear axle r , and measure the turning radius R value at each predetermined angle in turn. From the kinematic model, it can be known that the relationship between the turning radius R value and the hinge axis angle θ is: R*tanθ=L f +L r / cosθ; By Newton's iteration method: f(θ) = R*tanθ-(L f +L r / cosθ), θ=θ0-f(θ0) / f'(θ0); the precise value of the hinge axis rotation angle θ corresponding to the turning radius R can be calculated.

[0027] Prepare an unmanned articulated vehicle, which has an unmanned driving system that can control the turning and walking of the articulated vehicle, is equipped with an articulated shaft angle sensor, and is equipped with a steering calibration module. The connection method of each module of the vehicle is as follows Figure 3 .

[0028] The structure of the steering calibration module is as follows: Figure 4 .

[0029] 13 sets of characteristic steering angle values ​​are selected within the executable steering angle range of the articulated vehicle (the characteristic steering angle values ​​can be selected freely, and generally the more angle values ​​selected, the more accurate the calibration result).

[0030] Steering calibration process Figure 5 The complete process and device composition are as follows: 1. The steering calibration module (module) sends a steering calibration start signal and a predetermined steering wheel steering angle to be calibrated to the unmanned driving system; 2. The unmanned driving system sets the steering angle of the unmanned articulated vehicle steering wheel to the steering wheel steering angle that needs to be calibrated and controls the unmanned articulated vehicle to travel at a preset speed; 3. The unmanned driving system calculates the vehicle turning radius R at the current steering angle based on the positioning data; 4. The on-board articulated shaft angle sensor feeds back an angle reference value θ0; 5. The steering calibration module (module) reads and stores the angle reference value θ0 fed back by the articulated shaft angle sensor; Considering the value θ0 and the vehicle turning radius R at the current steering angle, 6. The steering calibration module (module) determines whether there is a predetermined steering wheel steering angle to be calibrated that has not been executed. If so, repeat steps 1-5. If not, the unmanned driving system controls the vehicle to stop. 7. The steering calibration module calculates the precise value θ of the articulated shaft angle corresponding to each turning radius R in each group of stored data to be calibrated according to the relationship between the turning radius R value of the articulated vehicle and the articulated shaft angle θ and the Newton iteration method. 8. The steering calibration module fits and outputs the corresponding relationship between the turning radius R and the articulated shaft angle θ to complete the steering parameter calibration of the unmanned articulated vehicle.

[0031] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating and calibrating the rotation angle of an articulated shaft of an articulated vehicle, characterized in that: include: Measure the distance L between the articulation axis and the front axle f , measure the distance L between the articulated axis and the rear axle r , and measure the turning radius R value at each predetermined angle in turn; calculate the exact value of the hinge axis angle θ corresponding to the turning radius R value by the following formula: f(θ)=R*tanθ-(L f +L r / cosθ), θ=θ0-f(θ0) / f'(θ0); The method comprises the following steps: 1) The steering calibration module sends a steering calibration start signal and a predetermined steering wheel steering angle to be calibrated to the unmanned driving system; 2) The unmanned driving system sets the steering angle of the steering wheel of the unmanned articulated vehicle to the steering angle of the steering wheel that needs to be calibrated and controls the unmanned articulated vehicle to travel at a preset driving speed; 3) The unmanned driving system calculates the vehicle turning radius R at the current steering angle based on the positioning data; 4) The vehicle-mounted articulated shaft angle sensor feeds back an angle reference value θ0; 5) The steering calibration module reads and stores the angle reference value θ0 fed back by the articulated shaft angle sensor and the vehicle turning radius R at the current steering angle; 6) The steering calibration module determines whether there is a predetermined steering wheel steering angle to be calibrated that has not been executed, and if so, repeats steps 1)-5), and if not, the unmanned driving system controls the vehicle to stop; 7) The steering calibration module calculates the precise value θ of the articulated shaft angle corresponding to each turning radius R in each stored set of data to be calibrated according to the relationship between the turning radius R value of the articulated vehicle and the articulated shaft angle θ and the Newton iteration method; 8) The steering calibration module fits and outputs the corresponding relationship between the turning radius R and the articulation axis angle θ to complete the steering parameter calibration of the unmanned articulated vehicle.

2. A control device, used to execute the method according to claim 1, characterized in that: The device comprises an unmanned driving system capable of controlling the turning and walking of an articulated vehicle, an articulated shaft angle sensor, and a steering calibration module; the unmanned driving system, the articulated shaft angle sensor, and the steering calibration module are interconnected for communication.

3. The control device according to claim 2, characterized in that: The device comprises a chassis domain controller; the unmanned driving system, the articulated shaft angle sensor, the steering calibration module and the chassis domain controller are connected to each other for communication.

4. An unmanned articulated vehicle equipped with the control device according to claim 2 or 3.

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