A control method for a joystick-controlled Mecanum wheel mobile platform

Abstract

The present invention discloses a control method for controlling the movement of a Mecanum wheel platform by a rocker, comprising: step 1, establishing a rocker coordinate system, step 2, moving the rocker to position A, step 3, collecting the voltages of the X-axis and the Y-axis when the rocker is located at position A, step 4, calculating the rocker combined speed and direction angle value according to the voltages of the X-axis and the Y-axis, step 5, the platform control system analyzing the speed and direction of each Mecanum wheel motor, and step 6, the platform control system calculating and analyzing the motor speed collected in real time and the motor speed and direction analyzed by the platform control system through a PID algorithm, and performing stable closed-loop control on the Mecanum wheel. The control method of the present invention realizes the control of the all-round and arbitrary speed movement of the Mecanum wheel platform.

Description

Technical Field

[0001] The invention relates to a mobile platform control method, in particular to a control method for a Mecanum wheel mobile platform controlled by a rocker. Background Art

[0002] Mecanum wheels have been applied in many fields due to their omnidirectional mobility, such as AGV mobile platforms, lateral parking, omnidirectional mobile forklifts, etc. However, most of the existing Mecanum wheels are only applied in a single or several special directions, such as forward movement, lateral movement, oblique movement, rotation and their combination. The reason is that there are few controllers that can set the Mecanum wheel mobile platform to move in any direction and at any speed, and joysticks and virtual joysticks are among them. It is a major difficulty to match the rotation amplitude of the joystick and virtual joystick with the direction and speed of the Mecanum wheel mobile platform (car).

[0003] Therefore, a specific implementation method of a joystick to control a Mecanum wheel mobile platform (car) in 360 degrees in all directions and at any speed (within the maximum speed) needs to be studied urgently. Summary of the invention

[0004] The main purpose of the present invention is to provide a control method for a joystick-controlled Mecanum wheel mobile platform, aiming to solve the technical problem that the existing Mecanum wheel mobile platform (vehicle) is not convenient for moving in any direction and at any speed within the maximum speed.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A control method for controlling the movement of a Mecanum wheel platform by using a rocker, comprising the following steps:

[0007] Step 1: Establish the joystick coordinate system;

[0008] Step 2: Move the joystick to position A;

[0009] Step 3: Collect the voltages of the X-axis and Y-axis when the joystick is at position A;

[0010] Step 4: Calculate the joystick combined velocity V and direction angle value D according to the X-axis and Y-axis voltages;

[0011] Step 5: Analyze the speed and direction of each Mecanum wheel motor and feed it back to the PID controller;

[0012] Step 6: Calculate and analyze the motor speed collected in real time by the speed sensor installed on the motor and the analyzed motor speed and direction, and perform closed-loop control on the Mecanum wheel.

[0013] The method for establishing the joystick coordinate system in step 1 includes the following steps:

[0014] Step 1.1, the joystick is provided with potentiometers in two vertical directions, one direction is the X-axis, and the other direction perpendicular to the X-axis is the Y-axis, and a rectangular coordinate system is established;

[0015] Step 1.2: Calibrate the joystick system according to rectangular coordinates;

[0016] Step 1.3: After calibration, the joystick system confirms the positive and negative directions and the origin range, thereby establishing the joystick coordinate system.

[0017] The calibration of the joystick system includes zero calibration and unit voltage calibration.

[0018] The method of zero calibration includes the following steps:

[0019] Step 1.2.1. Pull the joystick to the outermost circle and rotate it slowly for several circles;

[0020] Step 1.2.2, during the rotation process, continuously collect the voltages of the X-axis and Y-axis, and record the maximum and minimum values ​​of the voltages of the X-axis and Y-axis respectively;

[0021] Step 1.2.3, return the joystick to zero multiple times, and record the average values ​​of the X-axis and Y-axis voltage values ​​collected when the joystick returns to zero, and obtain the average value ADC_X_MID of the voltage value in the X-axis direction of the zero point, and the average value ADC_Y_MID of the voltage value in the Y-axis direction of the zero point;

[0022] Step 1.2.4, with ADC_X_MID and ADC_Y_MID as the center, calculate the error range according to the error percentage calibrated on the joystick nameplate. This error range is the zero range, and everything within this range is returned to the origin.

[0023] The error margin algorithm is as follows:

[0024] (X-axis voltage maximum value - X-axis voltage minimum value) * error percentage = X-axis error range size, ADC_X_MID is the X-axis error range size with the center value fluctuating up and down by half, and the X-axis error range is obtained;

[0025] (maximum Y-axis voltage - minimum Y-axis voltage) * error percentage = Y-axis error range. ADC_Y_MID is the Y-axis error range with half of the center value floating up and down, and the Y-axis error range is obtained.

[0026] The method of unit voltage calibration is as follows:

[0027] Step 1.2.6, the unit voltage of the half-axis with high voltage is the difference between the maximum voltage and the high boundary of zeroing divided by half a pixel; the unit voltage of the half-axis with low voltage is the difference between the low boundary of zeroing and the minimum voltage divided by half a pixel;

[0028] Step 1.2.7, save the obtained zero range value and unit voltage value to the memory so as to be extracted and used in subsequent joystick operations;

[0029] The pixel refers to the total number of speed gears.

[0030] The calculation of the direction angle value includes the following steps:

[0031] Step 4.1, respectively obtain the projection of the joystick center on the X-axis and Y-axis of the joystick coordinate system;

[0032] Step 4.2: Calculate the direction angle value by using trigonometric function on the projection on the X-axis and Y-axis.

[0033] The steps to analyze the motor speed and direction of the Mecanum wheel are as follows:

[0034] Step 5.1, set the maximum moving speed V_MAX of the Mecanum wheel platform;

[0035] Step 5.2, the center point of the mobile platform is the origin, the horizontal and vertical directions of the platform are set as the X-axis and Y-axis of the platform movement, and the positive and negative directions are determined;

[0036] Step 5.3, calculate the component speed of the platform in the X-axis and Y-axis directions respectively;

[0037] Step 5.4, determine the speed and direction of each Mecanum wheel according to the Mecanum wheel motion formula;

[0038] Step 5.5: Calculate the rotation speed of each Mecanum wheel based on the speed and radius of each Mecanum wheel.

[0039] Furthermore, the component velocity of the platform on the X-axis V_X=V / pixel*V_MAX*sin(D / 180*π); the component velocity of the platform on the Y-axis V_Y=V / pixel*V_MAX*cos(D / 180*π).

[0040] Furthermore, the speed of the roller on the X-axis is V_X / cos(π / 4); the speed of the roller on the Y-axis is V_Y / sin(π / 4).

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The control method of the rocker to control the movement of the Mecanum wheel platform of the present invention realizes the stable control of the rocker to control the movement of the Mecanum wheel platform in all directions and at any speed;

[0043] (2) The present invention establishes a rocker coordinate system to improve the accuracy of rocker control, and can quickly calculate the coordinates of the rocker center based on the coordinate system and the collected voltage value;

[0044] (3) The joystick coordinate system of this invention has been calibrated before leaving the factory, and the joystick zero range is set to avoid the shaking of the joystick at the origin, which causes the controlled car to shake, and avoids the problem of the origin shifting after the joystick ages;

[0045] (4) Before leaving the factory, the rocker coordinate system of the present invention undergoes a unit voltage calibration procedure to calculate the unit voltage of the half-axis with high voltage and the unit voltage of the half-axis with low voltage, respectively, to improve the accuracy of the rocker's control over the Mecanum wheel platform;

[0046] (5) The platform control system of the present invention uses a PID algorithm to stably and accurately control the rotation of the motor based on the real-time collected wheel motor speed and the analyzed motor speed and direction, thereby stably and accurately controlling the entire platform to move at any speed and in any direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1 A flow chart of a control method for controlling the movement of a Mecanum wheel platform using a joystick provided in an embodiment of the present invention.

[0049] Figure 2 A schematic diagram of a joystick coordinate system provided by an embodiment of the present invention.

[0050] Figure 3 A schematic diagram of the Mecanum wheel speed analysis provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] The remote-controlled Mecanum wheel platform includes a platform control system, a joystick embedded system connected to the platform control system, and a speed sensor.

[0053] like Figure 1 As shown, a control method for remotely controlling the movement of a Mecanum wheel platform of the present invention comprises the following steps:

[0054] Step 1. Establish a joystick coordinate system. The joystick is designed with potentiometers in two vertical directions. One direction is the X-axis of the joystick coordinate, and the other direction perpendicular to the X-axis is the Y-axis. The zero point position of the joystick is the origin to establish rectangular coordinates. The joystick embedded system performs zero point calibration and unit voltage calibration based on the rectangular coordinates. The calibrated parameters are saved in the FLASH of the joystick embedded system, and the FLASH data is read in the subsequent use mode. Based on this, the calibrated joystick embedded system reconfirms the origin, positive and negative directions, and establishes a joystick coordinate system that can accurately set the velocity vector.

[0055] Step 2. Move the joystick to position A. The physical joystick moves to position A, while the virtual joystick touches point A on the APP.

[0056] Step 3. Collect the voltages of the X-axis and Y-axis when the joystick is at position A. The potentiometers are located in two directions perpendicular to the joystick, namely, on the X-axis and the Y-axis. Within a circular range, the resistance of the two potentiometers changes as the joystick is pushed, and the resistance is proportional to the projection distance of the center of the joystick on the X-axis and the Y-axis. When the ideal joystick is in the rebound position, the resistance of the two potentiometer sliders is the median of the resistance range. Connect power to both ends of the potentiometer, and the joystick embedded system performs analog-to-digital conversion voltage acquisition at the variable pins of the two potentiometers, recorded as ADC_X and ADC_Y, respectively. Figure 2 shown.

[0057] Step 4: Calculate the joystick velocity V and direction angle D based on the X-axis and Y-axis voltages, and send the joystick velocity and direction angle values ​​to the mobile platform control system. If it is a physical joystick, the joystick system collects the voltages ADC_X and ADC_Y in the X-axis and Y-axis directions, converts them into coordinates, and then calculates the joystick velocity V and direction angle value D. If it is a virtual joystick, directly obtain the coordinates on the APP to calculate the joystick velocity V and direction angle value D.

[0058] Step 5: The platform control system analyzes the speed and direction of the Mecanum wheel motor according to the received rocker combined velocity V and direction angle value D, and feeds back to the PID algorithm.

[0059] Step 6: The platform control system uses the PID algorithm to calculate and analyze the motor speed collected in real time by the speed sensor set on the motor and the analyzed motor speed and direction, and performs closed-loop control on the Mecanum wheel. The PID algorithm is a control algorithm that combines three links: proportional, integral and differential. According to the motor speed and direction collected in real time by the speed sensor on the motor that controls the speed of the Mecanum wheel, and the deviation value of the speed and direction to be achieved analyzed by the platform control system, the encoder PID performs smooth and continuous closed-loop control on the motor, thereby changing the speed and direction of the Mecanum wheel, and then driving the entire platform to move.

[0060] The PID algorithm achieves a stable control of the Mecanum wheel speed according to the deviation between the input value and the actual motion state, thereby realizing the stable control of the rocker over the all-round movement and arbitrary speed movement of the Mecanum wheel platform.

[0061] The joystick embedded system is zero-calibrated at the factory.

[0062] The TDE test host computer sends a calibration command to enter the calibration mode, and then returns the collected values ​​to the host computer. After the staff confirms that the data is correct, they send a confirmation command to the joystick embedded system. The joystick embedded system saves the received data to FLASH so that the subsequent joystick embedded system can read the data on FLASH in the working mode. The signal transmission between the host computer and the joystick embedded system can be achieved through key triggering, serial port connection or USB and other communication methods. It should be noted that this calibration method is only implemented for the physical joystick. The virtual joystick directly obtains the coordinates on the APP, and there is no need to calculate and convert the coordinates like the physical joystick, so there is no need for zero point calibration. The joysticks described in the following calibration methods are all physical joysticks.

[0063] The joystick embedded system enters the calibration mode. The staff pulls the joystick to the outermost circle and rotates it slowly for several weeks. During the rotation process, it is equivalent to changing the resistance of the potentiometer to the maximum and minimum. During the rotation process, the joystick embedded system continuously collects the voltages on the X-axis and Y-axis, and records the maximum voltage ADC_X_MAX and the minimum voltage ADC_X_MIN on the X-axis, and the maximum voltage ADC_Y_MAX and the minimum voltage ADC_Y_MIN on the Y-axis. Pull the joystick to the outermost circle for many times and rotate it, then rebound to zero. Record the average value of the voltage values ​​of the X-axis and Y-axis when the joystick is zeroed, and obtain the average value ADC_X_MID of the voltage value in the X-axis direction of the zeroing point, and the average value ADC_Y_MID of the voltage value in the Y-axis direction of the zeroing point. With ADC_X_MID and ADC_Y_MID as the center, calculate the error range according to the error percentage calibrated on the joystick nameplate. This error range is the zeroing range, and everything within this range is returned to the origin.

[0064] The error range of the X-axis is obtained by subtracting the minimum value from the maximum value of the voltage on the X-axis and then multiplying it by the error percentage. Taking ADC_X_MID as the center value, add half of the X-axis error range to get the high boundary of the error range. Taking ADC_X_MID as the center value, subtract half of the X-axis error range to get the low boundary of the X-axis error range. The high boundary and the low boundary are the zeroing range of the joystick in the X-axis direction. For example, assuming that the error percentage of the joystick nameplate calibration is 20%, the collected ADC_X_MAX=3.3V, ADC_X_MIN=0.3V, ADC_X_MID=1.75V, then the error range is (3.3-0.3)*20%=0.6V, and the error range is 1.75-0.3=1.45V to 1.75+0.3=2.05V, that is, 1.45V-2.05V is the zeroing range on the X-axis.

[0065] The error range algorithm of the Y axis is the same as that of the X axis. Subtract the minimum value from the maximum value of the voltage on the Y axis, and then multiply it by the error percentage to get the error range on the Y axis. Take ADC_Y_MID as the center value, add half of the Y axis error range to get the high boundary of the error range. Take ADC_Y_MID as the center value, subtract half of the Y axis error range to get the low boundary of the Y axis error range. The high boundary and the low boundary are the zero range of the joystick in the Y axis direction.

[0066] Setting the zeroing range can prevent the joystick from shaking at the origin and causing the Mecanum wheel platform to shake. After the joystick ages, its origin will also shift. Allowing a certain zeroing point error range can avoid misoperation of the Mecanum wheel platform.

[0067] The joystick embedded system is calibrated to unit voltage at the factory.

[0068] Each time the value collected by the ADC increases by one unit voltage, the speed on that axis increases by one gear. The total number of speed gears is the pixel of that axis. In the joystick system, the horizontal pixel is the same as the vertical pixel, which means the number of scales on the X-axis and Y-axis is the same. Half of the scales on the X-axis and Y-axis are positive speed gears, and half are negative speed gears. However, since half of the mechanical zero point of the joystick is not the midpoint of the ADC, the unit voltage values ​​of the positive and negative half axes are different, so calibration is required.

[0069] The unit voltage on the side with high voltage is equal to the maximum voltage minus the high boundary of zeroing, and then divided by half a pixel. The unit voltage on the side with low voltage is equal to the low boundary of zeroing minus the minimum voltage, and then divided by half a pixel. For example, the collected ADC_X_MAX=3.3V, ADC_X_MIN=0.3V, 1.45V-2.05V is the zeroing range on the X-axis, and the pixel is 100. Then the unit voltage of the half axis with high voltage=(3.3-2.05) / 50=0.025V, and the unit voltage of the half axis with low voltage=(1.45-0.3) / 50=0.023V. That is, when the joystick moves towards the side with high voltage, the speed gear will jump every time the voltage changes by 0.025V; when the joystick moves towards the side with low voltage, the speed gear will jump every time the voltage changes by 0.023V.

[0070] After the calibration is completed, the staff will save the zero range data obtained by the calibration zero point and the unit voltage value obtained by the unit voltage calibration to FLASH so that the data can be retrieved in the subsequent working mode.

[0071] After calibration, the joystick embedded system uses ADC_X as the X-axis, ADC_Y as the Y-axis, and the zero range as the origin to establish a coordinate system and determine the positive and negative signs, thereby establishing a joystick coordinate system that can accurately set the velocity vector. The positive and negative sign setting can be set to set the semi-axis direction with large voltage as positive and the semi-axis direction with small voltage as negative. The setting of the positive and negative signs can be swapped, depending on the specific situation.

[0072] When the joystick moves to position A, the physical joystick determines the coordinates of the joystick center based on the projection of the joystick center on the X-axis and Y-axis, thereby calculating the joystick combined speed V and the direction angle value D. The joystick combined speed V is the speed gear of the joystick. The joystick embedded system periodically sends the joystick combined speed V and the direction angle value D to the platform control system of the Mecanum wheel platform via wired or wireless means. The platform control system parses the speed of each Mecanum wheel and feeds it back to the PID algorithm through the encoder for stable closed-loop control.

[0073] As a non-limiting example, this embodiment uses a mobile platform with four Mecanum wheels as an example for illustration. Figure 3As shown, the platform control system receives the rocker combined speed V and the direction angle value D and performs analysis. Assuming that the maximum moving speed of the platform is V_MAX (m / s), the set platform speed V1 = V / pixel*V_MAX, the longitudinal direction of the platform center is the X-axis, forward is positive, and the lateral direction of the platform center is the Y-axis, left is positive. Then the platform speed on the X-axis V_X = V / pixel*V_MAX*sin(D / 180*π), and the speed on the Y-axis V_Y = V / pixel*V_MAX*cos(D / 180*π). The speed is synthesized onto the roller, and the speeds of the roller on the X-axis and Y-axis are: V_X / cos(π / 4), V_Y / sin(π / 4), respectively. Suppose four Mecanum wheels are a, b, c, and d, and the following is obtained after analysis through the Mecanum wheel motion formula:

[0074] V_a=--V_Y / sin(π / 4)+V_X / cos(π / 4);

[0075] V_b=V_Y / sin(π / 4)+V_X / cos(π / 4);

[0076] V_c=V_Y / sin(π / 4)+V_X / cos(π / 4);

[0077] V_d=-V_Y / sin(π / 4)+V_X / cos(π / 4).

[0078] A positive result indicates that the Mecanum wheel is rotating forward, and a negative result indicates that the Mecanum wheel is rotating backward. The radius of the Mecanum wheel is known to be r. According to the relationship between the linear velocity and radius of the Mecanum wheel, the rotation speed of each Mecanum wheel can be obtained as N=V / (2π / r). The platform control system feeds back the parsed Mecanum wheel rotation speed to the PID controller through the encoder. The Mecanum wheels are controlled to rotate by motors one by one. The motors are provided with speed sensors to collect the rotation speed of each motor in real time, that is, to collect the rotation speed of the Mecanum wheel, and send the collected real-time rotation speed to the PID controller of the platform control system. The PID controller realizes stable closed-loop control of the Mecanum wheel through the PID algorithm according to the received real-time rotation speed of the Mecanum wheel and the parsed speed and direction of the Mecanum wheel, and realizes stable control of the Mecanum wheel platform in all directions and at any speed.

[0079] It is worth noting that the PID controller of the platform control system sets a speed limit for the control of the speed of the Mecanum wheel. The speed limit is the speed of the motor when the PWM duty cycle is X% when the motor is idling. The reserved 1-X% is used for PID adjustment to adapt to different ground frictions. The specific X% is adjusted according to actual needs. In this embodiment, X% is 85%. If the speed of the Mecanum wheel analyzed by the platform control system exceeds the speed limit in whole or in part, the speed of the Mecanum wheel with the highest speed analyzed is lowered to the speed limit, and the speeds of other Mecanum wheels are correspondingly lowered in proportion. The PID controller of the platform control system performs stable control according to the speed of the Mecanum wheel after the reduction and the real-time speed of the Mecanum wheel. Setting a speed limit for the speed of the Mecanum wheel plays a good protective role in the stable movement of the motor and the platform.

[0080] The control method of the rocker-controlled Mecanum wheel platform of the present invention solves the problem of the inflexible movement of the rocker-controlled Mecanum wheel platform, and realizes the control of the Mecanum wheel movement in all directions and at any speed. And through the factory zero calibration, the shaking of the rocker is avoided to cause the platform to cause misoperation, and the problem of the origin offset after the rocker is aged is avoided. Through the unit voltage calibration, the unit voltage value in the positive and negative directions is accurately confirmed, so that the control of the platform is more accurate.

[0081] The above description shows and describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention, through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A control method for controlling the movement of a Mecanum wheel platform by using a rocker, characterized in that: The following steps are involved: Step 1: Establish the joystick coordinate system; Step 2: Move the joystick to position A; Step 3: Collect the voltages of the X-axis and Y-axis when the joystick is at position A; Step 4: Calculate the joystick combined velocity V and direction angle value D according to the X-axis and Y-axis voltages; Step 5: Analyze the speed and direction of each Mecanum wheel motor; Step 6: Calculate and analyze the motor speed collected in real time by the speed sensor installed on the motor and the analyzed motor speed and direction, and perform closed-loop control on the Mecanum wheel.

2. The control method of a rocker-controlled Mecanum wheel platform according to claim 1, characterized in that: The method for establishing the rocker coordinate system in step 1 comprises the following steps: Step 1.1, the joystick is provided with potentiometers in two vertical directions, one direction is the X-axis, and the other direction perpendicular to the X-axis is the Y-axis, and a rectangular coordinate system is established; Step 1.2: Calibrate the joystick system according to rectangular coordinates; Step 1.3: After calibration, the joystick system confirms the positive and negative directions and the origin range, thereby establishing the joystick coordinate system.

3. The control method of a rocker-controlled Mecanum wheel platform according to claim 2, characterized in that: The calibration of the rocker system includes zero calibration and unit voltage calibration.

4. The control method of a rocker-controlled Mecanum wheel platform according to claim 3, characterized in that: The method for zeroing calibration comprises the following steps: Step 1.2.

1. Pull the joystick to the outermost circle and rotate it slowly for several circles; Step 1.2.2: During the rotation of the joystick, continuously collect the voltages of the X-axis and Y-axis, and record the maximum and minimum values ​​of the voltages of the X-axis and Y-axis respectively; Step 1.2.3, return the joystick to zero multiple times, and record the average values ​​of the X-axis and Y-axis voltage values ​​collected when the joystick returns to zero, and obtain the average value ADC_X_MID of the voltage value in the X-axis direction of the zero point, and the average value ADC_Y_MID of the voltage value in the Y-axis direction of the zero point; Step 1.2.4, with ADC_X_MID and ADC_Y_MID as the center, calculate the error range according to the error percentage calibrated on the joystick nameplate. This error range is the zero range, and everything within this range is returned to the origin.

5. The control method of a rocker-controlled Mecanum wheel platform according to claim 4, characterized in that: The algorithm for the error range is as follows: (X-axis voltage maximum value - X-axis voltage minimum value) * error percentage = X-axis error range size, ADC_X_MID is the X-axis error range size with the center value fluctuating up and down by half, and the X-axis error range is obtained; (maximum Y-axis voltage - minimum Y-axis voltage) * error percentage = Y-axis error range. ADC_Y_MID is the Y-axis error range with half of the center value floating up and down, and the Y-axis error range is obtained.

6. The control method of a joystick to control the movement of a Mecanum wheel platform according to claim 4, characterized in that: The method of unit voltage calibration is as follows: Step 1.2.6, the unit voltage of the half-axis with high voltage is the difference between the maximum voltage and the high boundary of zeroing divided by half a pixel; the unit voltage of the half-axis with low voltage is the difference between the low boundary of zeroing and the minimum voltage divided by half a pixel; Step 1.2.7, save the obtained zero range value and unit voltage value to the memory so as to be extracted and used in subsequent joystick operations; The pixel refers to the total number of speed gears.

7. The control method of a joystick to control the movement of a Mecanum wheel platform according to claim 1, characterized in that: The calculation of the direction angle value comprises the following steps: Step 4.1, respectively obtain the projection of the joystick center on the X-axis and Y-axis of the joystick coordinate system; Step 4.2: Calculate the direction angle value by using trigonometric function on the projection on the X-axis and Y-axis.

8. The control method of a joystick to control the movement of a Mecanum wheel platform according to claim 1, characterized in that: The steps for analyzing the motor speed and direction of the Mecanum wheel are as follows: Step 5.1, set the maximum moving speed V_MAX of the Mecanum wheel platform; Step 5.2, the center point of the mobile platform is the origin, the horizontal and vertical directions of the platform are set as the X-axis and Y-axis of the platform movement, and the positive and negative directions are determined; Step 5.3, calculate the component speed of the platform in the X-axis and Y-axis directions respectively; Step 5.4, synthesize the component speeds of the platform in the X-axis and Y-axis directions to the roller, and calculate the speeds of the roller in the X-axis and Y-axis; Step 5.5, determine the speed and direction of each Mecanum wheel according to the Mecanum wheel motion formula; Step 5.6: Calculate the speed of each motor based on the speed and radius r of each Mecanum wheel.

9. The control method of a rocker-controlled Mecanum wheel platform according to claim 8, characterized in that: The component velocity of the platform on the X-axis V_X=V / pixel*V_MAX*sin(D / 180*π); the component velocity of the platform on the Y-axis V_Y=V / pixel*V_MAX*cos(D / 180*π).

10. The control method of a joystick to control the movement of a Mecanum wheel platform according to claim 9, characterized in that: The speed of the roller on the X axis is V_X / cos(π / 4); the speed of the roller on the Y axis is V_Y / sin(π / 4).

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