CN101885351B - Split-type differential drive device and omnibearing movable automatic guided vehicle thereof - Google Patents

Abstract

The invention discloses a separable differential drive device and an omnidirectional mobile automatic guided vehicle, belonging to the field of automatic conveying equipment. The upper turntable of the device is fixed on the car body, and is coaxially assembled with the lower turntable through a thrust bearing. The upper turntable is equipped with an angle sensor and an electromagnetic clutch, and the lower turntable is equipped with a guide sensor and an on-board controller, and two sets including motor drivers, Wheeled mobile units with motor brakes, servo motors, rotary encoders, gear reducers and drive wheels. The inventive device has the advantages of simple structure, large carrying capacity, precise control and stable operation; the method fully utilizes the characteristics of the device, has simple control principle, good path adaptability, and has high stability, accuracy and rapidity.

Description

Separable differential drive device and its omni-directional mobile automatic guided vehicle

technical field

The invention relates to a separable differential drive device and its omni-directional mobile automatic guided vehicle, belonging to the field of automatic conveying equipment. the

Background technique

The driving/steering device is the motion actuator of the wheeled electric vehicle. According to the degree of freedom of plane motion, the automatic guided vehicle (AGV for short) has a non-complete movement mode with limited lateral motion and a full range of movement that can realize all plane motions. Way. The all-round mobile automatic guided vehicle can not only move forward and backward along the longitudinal direction of the car body, rotate around the center of the car body, but also move left and right along the lateral direction of the car body, and can move along the It can move in any direction in the plane, and has good maneuverability for limited working space. the

Omni-directional wheels, represented by Mecanum wheels and spherical wheels, can not only rotate around the main axis to achieve forward and backward movement, but also produce lateral movement along the main axis direction, which is a technical solution to realize omni-directional movement. , however, the mechanical structure of the omnidirectional wheel is complex and the manufacturing cost is high. Another technical solution is to realize all-round movement through the special layout of conventional wheels, such as a pair of dual steering drive wheel layouts whose directions are controlled by steering motors and whose speed is controlled by drive motors. However, the control system of this solution is relatively complicated. And the two-wheel steering synchronism of independent control is relatively poor. the

In order to improve the synchronization of two-wheel steering control, "Drive/Steering Mechanism of Automatic Guided Vehicle" (Patent No.: ZL200620028342.5) drives and connects the motor to the reducer through a steering positioning mechanism, and the output end of the reducer is connected to a drive Shaft, using an electromagnetic clutch to connect the two drive wheels with the two ends of the through-shaft in a clutch-type driving connection. The upper turntable of the steering positioning mechanism is fixed to the motor casing, and the lower turntable is fixed to the reducer casing; the relative rotation angle between the upper turntable and the lower turntable is detected by the angle sensor, and the zero position of the angle sensor is corrected by using the middle position switch and the positioning pit; The positioning pin is driven by the electromagnet of the upper turntable to sink into the positioning pit of the lower turntable to realize the locking between the upper turntable and the lower turntable. This device can ensure the synchronization of two-wheel steering control, but it has the following disadvantages: (1) It is difficult to accurately control the motion state of the driving wheel through clutch friction drive; (2) The device uses the motor and the reducer as the main Load-bearing structure, limited strength and stiffness are not suitable for heavy load conditions; (3) It is difficult to achieve precise locking between the upper turntable and the lower turntable at any angle by using the connection method of positioning pins and positioning pits; (4) The angle sensor needs The center position switch is used for centering calibration; (5) The structure of the driving wheel electromagnetic clutch in the device is relatively complicated. the

Since the Mecanum wheel and the spherical wheel can realize all plane movements, the omnidirectional mobile automatic guided vehicle using this wheel is not subject to non-holonomic constraints, and its motion control method is relatively simple. However, the mechanical structure of the omnidirectional wheel is complex and the manufacturing cost is high. , and it is difficult to be adaptive to the shape change of the running path. The automatic guided vehicle using conventional wheels cannot directly eliminate the lateral position deviation due to non-holonomic constraints. In the motion control, the longitudinal displacement of the car body needs to be used to indirectly eliminate the lateral position deviation. The motion control method is relatively complicated and requires a large amount of motion. space. the

Contents of the invention

The purpose of the present invention is to provide a separable differential drive device with simple structure, large load capacity, precise control and stable operation; and fully utilize the characteristics of the device to provide a control principle for omni-directional mobile automatic guided vehicles It is a motion control method that is simple, has good path adaptability, and has high stability, precision and speed. the

A separable differential drive device for a wheeled electric vehicle, characterized in that it includes an upper turntable and a lower turntable, wherein the upper turntable has a central hole, and the upper end of the lower turntable has a central shaft; the center hole of the upper turntable and the lower turntable The central shafts are coaxially assembled through thrust bearings; a cylindrical electromagnetic clutch is installed between the central hole of the upper turntable and the central shaft of the lower turntable; the above-mentioned lower turntable is symmetrically installed with two sets of wheels along both sides of the central axis The right wheeled mobile device includes a right motor driver, right motor brake, right servo motor, right rotary encoder, right reducer and right driving wheel, and the left wheeled mobile device includes a left motor driver, left motor brake , left servo motor, left rotary encoder, left reducer and left driving wheel; the above-mentioned lower turntable is also equipped with a guide sensor for detecting path deviation and an on-board controller for autonomous driving; the above-mentioned guide sensor, right rotary encoder The encoder and the left rotary encoder are connected to the on-board controller through the signal input circuit; the on-board controller is respectively connected to the right motor driver and the left motor driver, the right motor brake and the left motor brake through the signal output circuit; The angle sensor of the rotation angle between the lower turntable and the angle sensor is fixed on the upper end surface of the upper turntable, and its rotor is mechanically connected to the central axis of the lower turntable, and is connected to the vehicle-mounted controller on the lower turntable through a signal input circuit. the

The specific installation method of the above-mentioned electromagnetic clutch is as follows: the shell of the electromagnetic clutch is fixed on the center hole of the upper turntable. A clutch-type mechanical connection is made between the shafts. the

An omni-directional mobile automatic guided vehicle using the above-mentioned separable differential drive device is characterized in that: the separable differential drive device is installed in the center of the lower part of the car body, and the upper turntable and the car body are connected by a Rigid fixed connection or flexible suspension connection, the two have no relative movement in the horizontal direction; there are at least two free wheels installed around the bottom of the car body, and their movement speed and direction depend on the motion state of the car body; There are control battery packs for angle sensors, right rotary encoders, left rotary encoders, guidance sensors and on-board controllers; there are also installed on the car body for electromagnetic clutches, right motor brakes, left motor brakes, and right motor drivers. And the left motor driver supplies power to drive the battery pack. the

The working principle of the omni-directional movement of the automatic guided vehicle is as follows: the on-board controller independently controls two servo motors through two motor drivers, and then independently drives two drive wheels through two reducers, and each drive wheel The speed and direction of movement can be independently and accurately controlled, and the speed difference between the two driving wheels will make the lower turntable move along a circular arc track. The on-board controller controls the connection state between the lower turntable and the car body through the electromagnetic clutch. When there is no lock between the lower turntable and the car body, set the speed of the two driving wheels to be equal and opposite, and to adjust freely by rotating in situ around the central axis The movement direction of the lower turntable is detected by the angle sensor in real time; when the movement direction angle reaches a given value, the on-board controller stops the servo motor and immediately brakes through the motor brake, and then locks the lower turntable and the car body, so that The direction of motion of the two remains the same. Therefore, the automatic guided vehicle can move in any direction and angle in all directions while keeping the attitude of the vehicle body unchanged. the

Compared with the existing driving/steering device, the device of the present invention has the following advantages: (1) The structure is simple. The invention adopts the upper turntable, the lower turntable and the wheeled moving device of the modular structure, which has the advantages of simple structure, low manufacturing cost and good maintainability. (2) Large carrying capacity. The main bearing structure adopted in the present invention is a frustum-shaped upper turntable and a lower turntable. The central hole of the upper turntable and the central axis of the lower turntable are coaxially assembled through a thrust bearing. The whole device has sufficient strength and rigidity, and can be applied to heavy load cases. (3) precise control. The present invention independently and accurately controls the movement speed and direction of the two drive wheels through two sets of motor drivers and servo motors, and can form an effective speed difference to realize the steering control of the lower turntable and even the car body; The electromagnetic clutch drives the friction block to press the central axis of the lower turntable, which can realize the precise locking between the upper turntable and the lower turntable at any angle; the invention uses an absolute rotary encoder as the angle sensor, which does not need external devices for zero point calibration, and can be accurately locked. Measure the angle of rotation between the upper and lower turntables. (4) It runs smoothly. According to the carrying capacity of the automatic guided vehicle, the upper turntable and the vehicle body of the present invention adopt rigid fixed connection or flexible suspension connection to ensure effective contact between the driving wheel and the ground to generate sufficient driving force. the

The path adaptive tracking control method of the above-mentioned automatic guided vehicle is characterized in that: an adaptive tracking control method is adopted for running paths of different shapes,

Method 1. Improve the stability of the car body motion through the free state tracking control method. The specific method is: release the lock between the lower turntable and the car body through the electromagnetic clutch in the separable differential drive device; the guide sensor detects the lower turntable The path deviation between the ground guide line and the ground guide line is sent to the on-board controller; the on-board controller precisely controls the speed difference between the right drive wheel and the left drive wheel through the right servo motor and the left servo motor respectively, so that the lower The turntable follows the shape change of the running path and quickly adjusts its position and attitude; the car body does not directly track the shape change of the running path, but is driven by the tracking movement of the lower turntable, and makes relative rotation around the central axis of the lower turntable;

Method 2. Accurately adjust the position and attitude of the vehicle body through the omnidirectional tracking control method. The specific method is: while keeping the vehicle body posture unchanged, eliminate the path deviation of the automatic guided vehicle along any direction of motion, specifically divided into the following three step:

Step 1. Stop the automatic guided vehicle first, and release the lock between the lower turntable and the vehicle body through the electromagnetic clutch in the separable differential drive device; the guidance sensor detects the path deviation between the vehicle body and the ground guidance marking , and send it to the on-board controller; the on-board controller calculates the movement direction angle of the automatic guided vehicle, and then calculates the rotation direction and angle of the lower turntable relative to the car body; the on-board controller uses the right servo motor and the left servo motor Control two drive wheels, one to rotate forward and the other to rotate in reverse, and keep the two speeds the same; the lower turntable rotates around its central axis in a predetermined direction, and the on-board controller detects the rotation between the lower turntable and the car body in real time through the angle sensor Angle; when the rotation angle reaches the predetermined direction angle of motion, the on-board controller stops the right servo motor and the left servo motor, and immediately brakes through the right motor brake and the left motor brake, and the lower turntable stops rotating;

Step 2. Lock the lower turntable and the car body through the electromagnetic clutch in the separable differential drive device; the guidance sensor detects the path deviation between the car body and the ground guide marking, and sends it to the on-board controller; The controller) calculates the motion track of the automatic guided vehicle according to the path deviation; through the right servo motor and the left servo motor, the speed of the right driving wheel and the left driving wheel is precisely controlled, and the automatic guided vehicle follows the movement direction set in step 1 with an appropriate geometric The trajectory is close to the ground guidance marking to eliminate the path deviation of the vehicle body;

Step 3: Stop the automatic guided vehicle again, and release the lock between the lower turntable and the car body through the electromagnetic clutch in the separable differential drive device; the on-board controller calculates the relative position of the lower turntable relative to the car body The direction and angle of rotation; the on-board controller controls one of the two drive wheels to rotate forward and the other to rotate reversely through the right servo motor and the left servo motor respectively, and keep the two speeds at the same speed; the lower turntable rotates around its central axis in a predetermined direction , the on-board controller detects in real time whether the direction of the lower turntable coincides with the car body through the angle sensor; and the left motor brake brake immediately, and the lower turntable stops rotating; finally, the lower turntable and the car body are locked by the electromagnetic clutch in the separable differential drive device;

The self-adaptive tracking control method also includes method three. Method three is to realize the rapid movement of the vehicle through the locked state tracking control method. body; the guidance sensor detects the path deviation between the vehicle body and the ground guidance marking, and sends it to the on-board controller; the on-board controller adopts multi-step prediction optimal control or single-step prediction intelligence for different direction angle deviations Control, eliminate the path deviation of the automatic guided vehicle by adjusting the speed difference between the two driving wheels, and set the target speed of the motor servo control according to the speed difference control amount generated by the tracking control. the

When the direction angle deviation is not greater than 5°, the multi-step predictive optimal control uses the kinematics model to calculate a multi-step control sequence with optimal coordination of deviation correction, namely

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; N</span>}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; Nv</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Eliminate two kinds of path deviations synchronously and accurately; among them, e _θ (0) and _ed (0) are the direction angle deviation and lateral distance deviation between the vehicle body and the ground guidance marking detected by the guidance sensor; T _s is the control cycle of the on-board controller (31); W is the distance between the right drive wheel and the left drive wheel; v is the linear velocity of the center of the car body; Δv (k) is the speed difference control amount of the kth control cycle , k=0, 1, 2...., N-1; N is the total number of steps of the control sequence, and its value is the minimum integer value that satisfies the following constraints:

$\left\{\begin{array}{c}{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}\\ \mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, |Δv(k)| _max is the maximum amplitude item of the speed difference control sequence, and its calculation formula is:

|Δv(k)| _max ＝|Δv(0)|or|Δv(N-1)| (3)

λ is the change step size of the speed difference control variable sequence, and its calculation formula is:

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Nv</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Δv _max and Δa _max are the preset maximum amplitude and maximum rate of change of speed;

When the direction angle deviation is greater than 5°, the single-step predictive intelligent control uses the kinematics model to calculate a single-step control quantity that satisfies the optimal deviation state transformation strategy, and quickly and smoothly reduces the two path deviations. When the direction angle deviation decreases After reaching 5°, use multi-step predictive optimal control;

(a) If the path deviation e _θ (k) and _ed (k) have different signs, or _ed (k) = 0, first calculate the speed difference control amount to eliminate the direction angle deviation:

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

(b) If the path deviation e _θ (k) and _ed (k) have the same sign, or e _θ (k) = 0, first calculate the speed difference control amount to synchronously eliminate the two deviations:

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}\frac{\mathrm{<span\; class="notranslate">\; W</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}\frac{{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

If |Δv(k) ^P |<Δv _min , where Δv _min is the preset minimum speed amplitude, then adjust the speed difference control amount according to the following formula:

Δv(k) ^P ＝Δv(k-1)+sign(e _d (k))λ _min (7)

in, $\mathrm{sign}\left(x\right)=\left\{\begin{array}{cc}1& x>0\\ 0& x=0\\ -1& x<0\end{array}\right..---\left(8\right)$

λ _min is the preset minimum rate of change of speed;

(c) If |Δv(k) ^P -Δv(k-1)|≤λ _max , where, λ _max ＝Δa _max T _s , then the calculation formula of speed difference control is

Δv(k) = Δv(k) ^P (9)

Otherwise, the calculation formula of speed difference control quantity is

Δv(k)=Δv(k-1)+sign(Δv(k) ^P -Δv(k-1))λ _max (10)

If |Δv(k) ^P |＞Δv _max , then the calculation formula of speed difference control amount is

Δv(k)=sign(Δv(k) ^P )Δv _max (11)

Compared with the existing motion control methods of automatic guided vehicles, the method of the present invention has the following advantages: (1) fully utilizing the characteristics of the separable differential drive device, it is realized by using a conventional wheeled moving mechanism with simple structure and high cost performance Full range of movement in any direction. (2) The control principle is simple, and the lock-unlock-lock control process between the lower turntable and the car body is adopted to realize the free and precise adjustment of the movement direction of the lower turntable and even the car body. (3) The path adaptability is good. The high-stationary free-state tracking control method is adopted for the running path with complex shape changes, and the omni-directional tracking control method is used for the parking positioning point to accurately adjust the position and attitude of the car body. For long-distance running paths The rapid movement of the vehicle is realized by using the locked-state tracking control method. the

Description of drawings

Fig. 1 is a schematic diagram of the front view of the separable differential drive device of the present invention. the

Fig. 2 is a top view structural diagram of an omni-directional mobile automatic guided vehicle applying the device of the present invention. the

Fig. 3 is a schematic diagram of the control system of the device of the present invention. the

Fig. 4 is a schematic diagram of the connection between the separable differential drive device and the vehicle body. the

Fig. 5 is a control schematic diagram for adjusting the movement direction of the car body in all directions. the

Fig. 6 is a schematic diagram of the composition of the path adaptive tracking control method of the present invention. the

Fig. 7 is a control schematic diagram of the free state tracking control method. the

Fig. 8 is a control schematic diagram of the omnidirectional tracking control method. the

Fig. 9 is a schematic diagram of a kinematics model of a locked-state tracking control method. the

Fig. 10 is a classification diagram of deviation states of the locked state tracking control method. the

Fig. 11 is a schematic diagram of synchronous correction of the locked state tracking control method. the

Fig. 12 is a schematic diagram of the optimal deviation state conversion strategy of the locked state tracking control method. the

Label names in the figure: 1. Upper turntable; 2. Thrust bearing; 3. Angle sensor; 4. Lower turntable; 5. Electromagnetic clutch; 6. Friction block; 7. Right rotary encoder; 8. Right motor brake; 9 10. Right reducer; 11. Right driving wheel; 12. Connecting key of right driving wheel; 13. Right bearing seat; 14. Right rolling bearing; 15. Right fastening bolt; 16. Right retaining ring; 17 1. Left retaining ring; 18. Left fastening bolt; 19. Left rolling bearing; 20. Left bearing seat; 21. Left driving wheel connection key; 22. Left driving wheel; 23. Left reducer; 24. Left servo motor; 25 , left motor brake; 26, left rotary encoder; 27, car body; 28, right motor driver; 29, left motor driver; 30, guidance sensor; 31, on-board controller; 32, free wheel 1; 33, free Wheel 2; 34, free wheel 3; 35, free wheel 4; 36, control battery pack; 37, drive battery pack; 38, guide bolt; 39, load spring; 40, fastening bolt. In addition, the Y-axis is the self-direction of the vehicle body 27 , and the y-axis is the self-direction of the lower turntable 4 . the

Detailed ways

The composition structure of the separable differential drive device and the operation process of the path adaptive tracking control method of the present invention will be described in detail below according to the embodiments shown in the accompanying drawings. the

Referring to Fig. 1, the separable differential drive device of the present invention is composed of a separable upper turntable 1 and a lower turntable 4, wherein the upper turntable 1 has a central hole, and the upper end of the lower turntable 4 has a central shaft; the upper turntable 1 The center hole of the lower turntable 4 and the center shaft of the lower turntable 4 are coaxially assembled by the thrust bearing 2; while bearing the axial load, the center shaft of the lower turntable 4 can be freely rotated in the center hole of the upper turntable 1. A cylindrical electromagnetic clutch 5 is also installed between the central hole of the upper rotating disk 1 and the central axis of the lower rotating disk 4 . the

Referring to Fig. 1 and Fig. 2, two sets of wheeled moving devices are symmetrically installed on both sides of the lower turntable 4 along the central axis, and the right wheeled moving device includes a right motor driver 28, a right motor brake 8, a right servo motor 9, and a right rotary encoder. 7, right speed reducer 10 and right drive wheel 11, the left side wheeled mobile device includes left motor driver 29, left motor brake 25, left servo motor 24, left rotary encoder 26, left reducer 23 and left drive wheel 22 ;

The above-mentioned lower turntable 4 is also equipped with a guide sensor 30 for detecting path deviation and an on-board controller 31 for realizing autonomous driving;

Wherein, the output ends of the right motor driver 28 and the left motor driver 29 are electrically connected with the input ends of the right servo motor 9 and the left servo motor 24 respectively, and the right motor brake 8 and the left motor brake 25 are connected with the right servo motor 9 and the left servo motor respectively. The output shaft of motor 24 is carried out clutch type mechanical connection, and the rotor of right rotary encoder 7 and left rotary encoder 26 is connected with the output shaft of right servomotor 9 and left servomotor 24 respectively by key, and right servomotor 9 and left servomotor The output shaft of motor 24 is connected with the input shaft of right reducer 10 and left reducer 23 respectively by shaft coupling, and the output shaft of right reducer 10 and left reducer 23 is connected with the hub of right drive wheel 11 and left drive wheel 22 respectively. Through the key connection, the right bearing seat 13 and the left bearing seat 20 are respectively connected through the right rolling bearing 14 and the left rolling bearing 19, and the right retaining ring 16 and the left retaining ring are respectively connected by the right fastening bolt 15 and the left fastening bolt 18 17 is fixed on the output shaft end faces of the right speed reducer 10 and the left speed reducer 23. Guide sensor 30, right rotary encoder 7 and left rotary encoder 26 are connected with vehicle-mounted controller 31 by signal input circuit; Vehicle-mounted controller 31 is connected with right motor driver 28 and left motor driver 29, right motor brake respectively by signal output circuit 8 links to each other with left motor brake 25. the

Referring to Fig. 2 and Fig. 3, the on-board controller 31 detects the path deviation between the lower turntable 4 and the ground guide marking through the guide sensor 30; The motion speed and direction of the servo motor 24, immediately brake the right servo motor 9 and the left servo motor 24 through the right motor brake 8 and the left motor brake 25; Machine 23 transmits the rotating speed and torque to the right driving wheel 11 and the left driving wheel 22, and the motion speed and direction of each driving wheel can be independently and accurately controlled; and through the right rotary encoder 7 and the left rotary encoder 26 The speed and displacement information of each driving wheel is fed back to the on-board controller 31 . When the speeds of the two driving wheels are equal and in the same direction, the lower turntable 4 moves along a straight line; when the speeds of the two driving wheels are different and in the same direction, the lower turntable 4 moves along a curved track; the speeds of the two driving wheels are equal and opposite , the lower turntable 4 rotates in situ around the central axis. the

Referring to FIGS. 1 and 2 , the upper turntable 1 is equipped with an angle sensor 3 that detects the rotation angle between it and the lower turntable 4 . The outer shell of the sensor is fixed on the upper end surface of the upper turntable 1, and its rotor is connected with the central axis of the lower turntable 4 through a key, and is connected with the vehicle-mounted controller 31 on the lower turntable 4 through a signal input circuit, and the feedback of the lower turntable 4 and the upper turntable 1 According to the angle of rotation, the direction of motion of the lower turntable 4 can be calculated. the

Referring to Fig. 1 and Fig. 2, the shell of electromagnetic clutch 5 is fixed on the center hole of upper turntable 1, and whether its electromagnetic coil is energized is controlled by the drive circuit of vehicle-mounted controller 31, and through the friction blocks 6 that are evenly distributed in the circumferential direction and the lower turntable 4 A clutch-type mechanical connection is made between the central shafts. When the electromagnetic coil of the electromagnetic clutch 5 is energized, the friction block 6 is sucked back, and it has no pressing effect on the central axis of the lower turntable 4, and the central axis of the lower turntable 4 can rotate freely in the center hole of the upper turntable 1, thereby adjusting The rotation angle between the lower turntable 4 and the upper turntable 1. When the electromagnetic coil of the electromagnetic clutch 5 was de-energized, the clip spring promoted the friction block 6 to compress the central axis of the lower turntable 4, and there was no relative rotation between the lower turntable 4 and the upper turntable 1. the

Referring to FIG. 2 and FIG. 4 , the separable differential drive device is installed in the lower center of the vehicle body 27 . According to the load capacity of the automatic guided vehicle and the smoothness of the running road surface, the upper turntable 1 and the car body 27 can be rigidly fixedly connected by fastening bolts 40, or can be flexibly suspended by using guide bolts 38 and load springs 39 connect. The difference between these two connections is only whether the upper turntable 1 and the car body 27 can be displaced in the vertical direction, but there is no relative movement in the horizontal direction. Therefore, the free rotation of the lower turntable 4 relative to the upper turntable 1 is The lower turntable 4 is free to rotate relative to the car body 27 . Two free wheels with supporting functions are respectively installed at the front and the rear below the car body 27. The speed and direction of its movement depend on the motion state of the car body 27. Cooperating with the driving wheels of the lower turntable 4 to realize the automatic guided vehicle turn. the

Also installed on the car body 27 is the control accumulator pack 36 for angle sensor 3, right rotary encoder 7 and left rotary encoder 26, guide sensor 30, vehicle-mounted controller 31 power supply; Electromagnetic clutch 5 , right motor brake 8 and left motor brake 25 , right motor driver 28 and left motor driver 29 power the drive battery pack 37 . Because the battery pack and the load with larger mass are installed on the car body 27, the inertia of the lower turntable 4 is relatively small, and the steering and straight-ahead motion can be flexibly completed through the differential control of the two driving wheels. the

Referring to Figure 5, the control process for adjusting the direction of movement of the car body in all directions is as follows:

In Fig. 5. (a), at first the car body 27 is in a static state, and the on-board controller 31 controls the electromagnetic coil energization of the electromagnetic clutch 5 through its drive circuit, and the friction block 6 is sucked back, and it is opposite to the central axis of the lower turntable 4. No compression. The vehicle-mounted controller 31 controls the right servo motor 9 through the right motor driver 28, drives the right driving wheel 11 to rotate in reverse through the right reducer 10; controls the left servo motor 24 through the left motor driver 29, drives the left driving wheel 22 through the left reducer 23 Forward rotation; And ensure that the rotational speed of right drive wheel 11 and left drive wheel 22 is the same, the central shaft of lower turntable 4 rotates freely in the center hole of last turntable 1. the

Since the quality of the car body 27 is much greater than that of the lower turntable 4, and the frictional force suffered by the central axis of the lower turntable 4 rotating in the center hole of the upper turntable 1 is very small, the posture of the car body 27 (ie, the Y-axis direction) While remaining unchanged, the lower turntable 4 rotates in situ around its central axis to freely and precisely adjust its movement direction (ie, the y-axis direction). During this process, the on-board controller 31 detects the rotation angle between the lower turntable 4 and the vehicle body 27 in real time through the angle sensor 3 , that is, the angle between the y-axis and the Y-axis. the

In Fig. 5.(b), when the included angle reaches a predetermined motion direction angle (in the embodiment, the included angle between the y-axis and the Y-axis is 90°), the vehicle-mounted controller 31 passes the right motor driver 28 and The left motor driver 29 controls the right servo motor 9 and the left servo motor 24 to stop rotating, and immediately brakes the right servo motor 9 and the left servo motor 24 by the right motor brake 8 and the left motor brake 25 . the

Then, the vehicle-mounted controller 31 controls the electromagnetic coil de-energization of the electromagnetic clutch 5 by its driving circuit, and the stage clip promotes the central axis of the friction block 6 to compress the lower turntable 4, and there is no relative rotation between the lower turntable 4 and the car body 27, and the y The included angle between the axis and the Y axis is locked to a predetermined motion direction angle. the

Referring to FIG. 6 , the present invention is oriented to a separable differential drive automatic guided vehicle, and adopts an adaptive tracking control method for running paths of different shapes: for curved paths with complex shape changes, the gap between the lower turntable 4 and the vehicle body 27 is released. The locking of high stability free state tracking control method is adopted; for the parking positioning point on the straight line path, the locking-unlocking-locking control process between the lower turntable 4 and the car body 27 is used, and the omni-directional tracking control method is used to accurately Adjust the position and attitude of the car body; on the long-distance road section on the straight path, lock the lower turntable 4 and the car body 27, and adopt the locked state tracking control method to realize the rapid movement of the vehicle. the

Referring to Fig. 7, the control process of the free state tracking control method of the present invention is as follows: when the automatic guided vehicle enters a curved path with complex shape changes, the vehicle-mounted controller 31 controls the electromagnetic coil energization of the electromagnetic clutch 5 through its drive circuit, The friction block 6 is sucked back, and it has no pressing effect on the central axis of the lower rotating disk 4, and the locking between the lower rotating disk 4 and the car body 27 is released. the

On the one hand, only the light guide sensor 30, the on-board controller 31 and two sets of wheeled mobile devices are installed on the lower turntable 4, the guide sensor 30 can be used to detect the path deviation of the ground guide marking in real time, and It is sent to the vehicle-mounted controller 31; the vehicle-mounted controller 31 calculates and outputs the speed difference control amount of the two driving wheels through efficient deviation correction, and then accurately controls the speed of the right driving wheel 11 and the left driving wheel 22 through the right servo motor 9 and the left servo motor 24 respectively. The actual speed makes the lower turntable 4 with little inertia adjust its position and posture in time according to the shape change of the curved path. During the path tracking process shown in FIG. 7 , the center of the lower turntable 4 is always located on the curved path, and its own direction (y-axis) always points to the tangent direction of the curved path. It can be seen that this control method significantly improves the speed and accuracy of the lower turntable 4 in the path tracking process, and completely avoids the problem of tracking failure caused by the ground guide markings exceeding the effective detection range of the guide sensor 30 . the

On the other hand, the heavy battery pack and the load are all mounted on the car body 27, and it is difficult for the car body 27 with high inertia to adjust its position and posture in time according to the shape change of the curved path. Therefore, the car body 27 does not directly follow the shape change of the curved path, but is driven by the lower turntable 4 to rotate around the central axis of the lower turntable 4 while moving with the direction of movement of the lower turntable 4 . During the path tracking process, the rate of change of the attitude angle of the car body 27 is slower than that of the lower turntable 4, as shown in Figure 7. (a), the self-direction (y-axis) of the lower turntable 4 starts to deflect along the tangential direction of the curved path, while The self-direction (Y-axis) of the car body 27 is still along the original straight path direction. Moreover, the change amplitude of the attitude angle of the vehicle body 27 is smaller than that of the lower turntable 4, as shown by the dotted line and the solid line in FIG. 7 . It can be seen that the rapidly changing running posture state of the lower turntable 4 has limited influence on the vehicle body 27, and this control method can ensure the stability of the vehicle body 27 running on a complex curved path. the

Referring to Fig. 5 and Fig. 8, the omni-directional tracking control method of the present invention adopts the lock-unlock-lock control process between the lower turntable and the car body to realize the movement of the AGV in any direction. Taking the direct elimination of the lateral position deviation of the automatic guided vehicle in Figure 8 as an example, the control process of the omnidirectional tracking control method is illustrated. the

In Fig. 8.(a), the angular deviation between the automatic guided vehicle and the running path is 0, and the lateral position deviation is _ed , which will be directly eliminated while keeping the vehicle body 27’s own direction (Y axis) unchanged. e _d .

In Fig. 8.(b), the automatic guided vehicle is stopped first, and the locking between the lower turntable 4 and the vehicle body 27 is released through the electromagnetic clutch 5 in the separable differential drive device. The guidance sensor 30 detects the path deviation between the vehicle body 27 and the ground guidance marking, and sends it to the on-board controller 31; the on-board controller 31 calculates the movement direction angle of the automatic guided vehicle accordingly, and then calculates the direction angle of the lower turntable. 4 Relative to the car body 27, it needs to rotate clockwise by 90°; the on-board controller 31 controls the right drive wheel 11 to rotate in the reverse direction through the right servo motor 9, and controls the left drive wheel 22 to rotate in the forward direction through the left servo motor 24, and maintains the speed of both The same; the lower turntable 4 rotates clockwise around its central axis, and the on-board controller 31 detects the rotation angle between the lower turntable 4 and the vehicle body 27 in real time through the angle sensor 3 . When the rotation angle reached 90°, the vehicle-mounted controller 31 stopped the right servo motor 9 and the left servo motor 24, and braked immediately by the right motor brake 8 and the left motor brake 25, and the lower turntable 4 stopped rotating, and its own direction (y Axis) is adjusted to be perpendicular to the side of the vehicle body of the running path. the

In Fig. 8.(c), the lower turntable 4 and the vehicle body 27 are locked by the electromagnetic clutch 5 in the separable differential drive device, and the direction of the lower turntable 4 itself (y-axis) and the direction of the vehicle body 27 itself (Y-axis) The angle between them is kept at 90°. The on-board controller 31 precisely controls the right drive wheel 11 and the left drive wheel 22 to rotate forward at the same speed through the right servo motor 9 and the left servo motor 24. The ground guideline moves. The guidance sensor 30 detects the lateral position deviation _ed of the automatic guided vehicle in real time. When the _ed is eliminated to zero, the on-board controller 31 stops the right servo motor 9 and the left servo motor 24, and passes the right motor brake 8 and the left motor The brake 25 brakes immediately, and the automatic guided vehicle stops moving.

In Fig. 8.(d), the locking between the lower turntable 4 and the vehicle body 27 is released through the electromagnetic clutch 5 in the separable differential drive device. The on-board controller 31 calculates according to the existing attitude of the car body 27 that the lower turntable 4 needs to rotate 90° counterclockwise with respect to the car body 27; 24 controls the left drive wheel 22 to rotate in the opposite direction, and keeps both speeds the same; the lower turntable 4 rotates counterclockwise around its central axis, and the on-board controller 31 detects the rotation angle between the lower turntable 4 and the car body 27 in real time through the angle sensor 3 . When the rotation angle reached 90°, the vehicle-mounted controller 31 stopped the right servo motor 9 and the left servo motor 24, and braked immediately by the right motor brake 8 and the left motor brake 25, and the lower turntable 4 stopped rotating, and its own direction (y axis) returns to coincide with the direction (Y axis) of the car body 27 itself. Finally, the lower turntable 4 and the vehicle body 27 are locked by the electromagnetic clutch 5 in the separable differential drive. the

Referring to Fig. 9, the lock state tracking control method of the present invention locks the lower turntable 4 and the car body 27 through the electromagnetic clutch 5 in the separable differential drive device, ΣXOY is a fixed coordinate system, and Σxoy is the position of the car body 27. In the vehicle coordinate system, the abscissa of the intersection point of the guide marking and the x-axis is the lateral position deviation _ed , the angle between the tangent direction of the guide marking and the y-axis is the direction angle deviation e _θ , when the tangent direction turns counterclockwise to y e _θ <0 when turning to the y-axis clockwise, and e _θ >0 when turning clockwise to the y-axis. The linear velocity of the left driving wheel 22 and the right driving wheel 11 are v _l and v _r respectively, the translational linear velocity of the center of the vehicle body 27 is v, and the rotational angular velocity is ω.

When the guide sensor 30 detects a path deviation, the on-board controller 31 generates a speed difference control amount Δv between the right drive wheel 11 and the left drive wheel 22 through the motor servo control, so that the vehicle body 27 moves along the instantaneous center of C. The circular arc track moves to eliminate the path deviation, and keeps the size of the vehicle body 27 centerline velocity v constant, that is

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}\\ {\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Assuming that the distance between the right driving wheel 11 and the left driving wheel 22 is W, then the angular velocity of the vehicle body 27 rotating along the instantaneous center of C is:

$\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Let the control cycle of the on-board controller 31 be T _s , set the direction angle deviation of the current state k to be e _θ (k), and the direction angle deviation of the next state k+1 is:

${\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The lateral distance deviation of the next state k+1 is:

${\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; v\&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The kinematic model of the automatic guided vehicle is:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Considering the limited execution capability of the servo motor and motor driver, the amplitude and step size of the speed difference control variable Δv(k) must meet the following conditions:

$\left\{\begin{array}{c}<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}\\ \mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Wherein, Δv _max and Δa _max are preset maximum amplitude and maximum rate of change of speed.

Under the constraint of condition (6), the path deviation of the current state may not be completely eliminated in one control cycle. From the perspective of overall optimization of multiple control cycles, with the goal of optimizing the coordination of two path deviation elimination, a N Step optimal control sequence Δv(k), (k=0, 1...N-1), eliminates the two path deviations to zero at the same time, that is, meets the control objective:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Minimizing the number of control steps N under the constraint of condition (6) can achieve the fastest deviation elimination process that the motor drive system can achieve. On this basis, the quadratic integral of the speed difference control variable is used as the objective function to describe the coordination of deviation correction, namely

$\mathrm{<span\; class="notranslate">\; J</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

When the direction angle deviation is not greater than 5°, the locked-state tracking control method of the present invention adopts multi-step predictive optimal control. For the system whose state equation is (5), under the constraint of condition (6), by minimizing The objective function (8) and the number of control steps N realize a deviation elimination process with the best coordination and rapidity within the capability of the motor drive system, and finally meet the control objective (8), so that the deviations of the two paths can be eliminated simultaneously to Zero and maintain the unbiased tracking state. the

According to the Lagrange undetermined sequence method, introduce the undetermined sequence to the state equation (5):

{λ(k+1)}={[λ ₁ (k+1)λ ₂ (k+1)] ^T } (9)

The Hamilton function is:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \{</span>\begin{array}{}\end{array}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right]<span\; class="notranslate">\; +</span>\left[\begin{array}{c}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\\ <span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\end{array}\right]\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

The speed difference control variable sequence Δv(k) that can make the objective function (8) obtain a minimum value satisfies the following conditions:

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>}\\ \frac{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

According to the condition (11), the speed difference control sequence can be obtained as:

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; N</span>}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; Nv</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

Wherein, the total number of steps of the control quantity sequence is N≥2, and the current number of control steps k=0, 1, 2..., N-1. the

In the speed difference control variable sequence, the calculation formula of the maximum amplitude item is:

|Δv(k)| _max ＝|Δv(0)|or|Δv(N-1)| (13)

The change step size of the speed difference control variable sequence is:

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;a</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Nv</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}\mathrm{<span\; class="notranslate">\; v</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

In order to ensure that all speed difference control variables Δv(k) satisfy condition (6), it is only necessary to satisfy

$\left\{\begin{array}{c}{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}\\ \mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

According to the condition (15), the total number of steps N of the control quantity sequence of the multi-step predictive optimal control can be calculated. the

Referring to Fig. 10, the locking state tracking control method according to the present invention is divided into four kinds of deviation states according to the relationship between the two path deviations, and the conversion process between the deviation states is studied for the large deviation situation with the direction angle deviation greater than 5° , quickly and smoothly reduce the deviation of the two paths through single-step predictive intelligent control, and then use multi-step predictive optimal control when the direction angle deviation is reduced to 5°. the

Referring to Figure 11, the single-step predictive intelligent control of the present invention makes the moving direction of the automatic guided vehicle move from the y-axis of the vehicle coordinate system to the point C as the center of the circle and |R| as the radius The circular arc oB tangentially transitions to the guide marking line, the two path deviations can be eliminated to zero synchronously, and the movement radius is

$<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; oC</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; oA</span>}}{\mathrm{<span\; class="notranslate">\; the\; tan</span>}<span\; class="notranslate">\; \&angle;</span>\mathrm{<span\; class="notranslate">\; oCA</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}{<span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}\frac{{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; |</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

When the speed difference control amount is not zero, there is the following relationship between the radius of the circular motion and the angular velocity:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; v</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="wxya"\; filenames="DEST\_PATH\_HSB00000552159900011.png"\; state="\{\{state\}\}">wxya</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; )</span>$

From equations (16) and (17), the speed difference control quantity for synchronously eliminating the two deviations can be obtained as:

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; P</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; v</span>}\frac{\mathrm{<span\; class="notranslate">\; W</span>}\mathrm{<span\; class="notranslate">\; the\; tan</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; the\; tan</span>}\frac{{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 18</span>}<span\; class="notranslate">\; )</span>$

Considering the rapidity requirements of the deviation elimination process, the speed difference control value calculated by formula (18) needs to meet:

|Δv(k) ^P |≥Δv _min (19)

Wherein, Δv _min is the preset minimum velocity amplitude.

If the condition (19) is satisfied, define the same-sign deviation state as the same-sign deviation I state, and directly use the synchronous speed difference control variable calculated by formula (18); otherwise, define it as the same-sign deviation II state, which is the same-sign deviation state To change the deviation I state, it is necessary to increase the ratio of the direction angle deviation to the lateral position deviation, and adjust the speed difference control amount to the direction of increasing the direction angle deviation, that is

Δv(k) ^P ＝Δv(k-1)+sign(e _d (k))λ _min (20)

in, $\mathrm{sign}\left(x\right)=\left\{\begin{array}{cc}1& x>0\\ 0& x=0\\ -1& x<0\end{array}\right..---\left(\mathrm{twenty\; one}\right)$

λ _min is the preset minimum rate of change of speed.

For the state of zero angle deviation, the speed difference control variable calculated by formula (18) is zero, and this deviation state can be regarded as a special case of the same sign deviation II state. the

It can be seen from formula (5) that for the different-sign deviation state and the zero-distance deviation state, the direction angle deviation will continuously generate new lateral distance deviations, so it is necessary to eliminate the direction angle deviation as soon as possible. From formula (5), it can be obtained that the speed difference control variable to eliminate the direction angle deviation to zero is:

$\mathrm{<span\; class="notranslate">\; \&Delta;v</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; W</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; twenty\; two</span>}<span\; class="notranslate">\; )</span>$

In order to make the magnitude and change step of the speed difference control variable Δv(k) satisfy the condition (6), judge whether the Δv(k) ^P calculated by the formulas (18), (20) and (22) satisfies the following conditions:

If |Δv(k) ^P -Δv(k-1)|≤λ _max , where, λ _max ＝Δa _max T _s , then the calculation formula of speed difference control is

Δv(k) = Δv(k) ^P (23)

Otherwise, the calculation formula of speed difference control quantity is

Δv(k)=Δv(k-1)+sign(Δv(k) ^P -Δv(k-1))λ _max (24)

If |Δv(k) ^P |＞Δv _max , then the calculation formula of speed difference control amount is

Δv(k)=sign(Δv(k) ^P )Δv _max (25)

Referring to Fig. 12, the single-step predictive intelligent control of the present invention is to quickly and smoothly reduce the deviation of the two paths, and an optimal deviation state conversion strategy is designed according to the conversion process between the deviation states. For the different-sign deviation state and the zero-distance deviation state, the direction angle deviation will continuously generate new lateral distance deviations, and the direction angle deviation can be eliminated to zero as soon as possible by using formula (22), and transformed into the zero-angle deviation state and the same-sign deviation II state . At this time, the control amount of synchronous speed difference calculated according to formula (18) is very small, which does not meet the rapidity requirement of the deviation elimination process. No. Deviation I state. At this time, according to formula (18), the speed difference control quantity for synchronously eliminating the deviation of the two paths can be calculated. If the control quantity satisfies the constraint of condition (15), it will enter into the non-deviation tracking state; The cyclic process of deviation state transition. the

Claims (3)

1. A separable differential drive for a wheeled electric vehicle, characterized in that it comprises an upper turntable (1) and a lower turntable (4), wherein the upper turntable (1) has a central hole, and the upper end of the lower turntable (4) The surface has a central axis; the central hole of the upper turntable (1) and the central axis of the lower turntable (4) are coaxially assembled through a thrust bearing (2); the center hole of the upper turntable (1) and the lower turntable (4) A cylindrical electromagnetic clutch (5) is also installed between the central shafts; The above-mentioned lower turntable (4) is equipped with two sets of wheeled moving devices symmetrically along both sides of the central axis, and the right side wheeled moving device includes a right motor driver (28), a right motor brake (8), a right servo motor (9), Right rotary encoder (7), right speed reducer (10) and right drive wheel (11), left side wheel type mobile device comprises left motor driver (29), left motor brake (25), left servo motor (24), Left rotary encoder (26), left reducer (23) and left driving wheel (22); The above-mentioned lower turntable (4) is also equipped with a guide sensor (30) for detecting path deviation and an on-board controller (31) for realizing autonomous driving; Above-mentioned guide sensor (30), right rotary encoder (7) and left rotary encoder (26) link to each other with vehicle-mounted controller (31) by signal input circuit; The motor driver (28) links to each other with the left motor driver (29), the right motor brake (8) and the left motor brake (25); The above-mentioned upper turntable (1) is equipped with an angle sensor (3) that detects the angle of rotation between it and the lower turntable. The central shaft is mechanically connected, and is connected with the vehicle-mounted controller (31) on the lower turntable (4) through a signal input circuit. 2. A separable differential drive device according to claim 1, characterized in that the shell of the electromagnetic clutch (5) is fixed on the center hole of the upper turntable (1), and whether the electromagnetic coil is energized is determined by the on-board The driving circuit of the controller (31) is controlled, and a clutch type mechanical connection is performed between the friction blocks (6) evenly distributed in the circumferential direction and the central shaft of the lower turntable (4). 3. The omni-directional mobile automatic guided vehicle utilizing the separable differential drive device according to claim 1, characterized in that: The separable differential drive device is installed in the center below the car body (27), and the upper turntable (1) and the car body (27) are connected by a rigid fixed connection or a flexible suspension connection, and the two have no relative movement in the horizontal direction; At least 2 free wheels are installed around the bottom of the car body (27), the speed and direction of which are determined by the state of motion of the car body (27); Also installed on the car body (27) is the control storage battery for angle sensor (3), right rotary encoder (7) and left rotary encoder (26), guide sensor (30), vehicle-mounted controller (31) power supply group(36); Also installed on the car body (27) is the driving accumulator group ( 37). the

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