WO2023279918A1

WO2023279918A1 - Motion control method and system for dual-steering-wheel autonomous moving device, and program product

Info

Publication number: WO2023279918A1
Application number: PCT/CN2022/098137
Authority: WO
Inventors: 赵雨辰; 赵安; 陈志伟; 唐文庆
Original assignee: 灵动科技（北京）有限公司
Priority date: 2021-07-05
Filing date: 2022-06-10
Publication date: 2023-01-12
Also published as: CN115576310A

Abstract

Provided in the present invention is a motion control method for a dual-steering-wheel autonomous moving device. The motion control method comprises the following steps: step S1, acquiring a planned path trajectory; step S2, determining a series of linear velocities υ, angular velocities ω and rudder angles Ω, which correspond to segments of the path trajectory, of an autonomous moving device on the basis of a differential motion model and the planned path trajectory, wherein the rudder angle Ω represents the included angle between a motion direction of the autonomous moving device and the longitudinal axis of the autonomous moving device, and the rudder angle Ω remains unchanged in the same segment of the path trajectory; and step S3, enabling the autonomous moving device to move according to the determined linear velocities υ, angular velocities ω and rudder angles Ω. The present invention further relates to a computer program product, and a motion control system for a dual-steering-wheel autonomous moving device. By means of the present invention, a control method for a dual-steering-wheel autonomous moving device can be simplified.

Description

Motion control method and system and program product of dual steering wheel autonomous mobile equipment

technical field

The present invention relates to the field of motion control of autonomous mobile equipment, in particular to a motion control method for dual steering wheel autonomous mobile equipment, a computer program product and a motion control system for dual steering wheel autonomous mobile equipment.

Background technique

With rapid economic growth and rising labor costs, autonomous mobile devices, such as mobile robots or logistics vehicles, are increasingly used. The motion system of the existing autonomous mobile equipment mainly adopts a differential wheel motion system or a steering wheel motion system. According to the number of driving wheels, the steering wheel motion system is often divided into single steering wheel motion system, double steering wheel motion system and multiple steering wheel motion system. Different motion systems for autonomous mobility devices have their own advantages and disadvantages.

The differential wheel motion system realizes the steering through the differential motion of the two wheels. The steering radius, speed, and angular velocity during steering are all determined by the two differential wheels. The differential wheel motion system has low requirements on the driving motor and control precision, so the cost is low. However, the kinematic precision of the differential wheel kinematic system is low, so it cannot be adapted to occasions with high precision requirements.

By adjusting the rotation angle and speed of the two steering wheels, the dual steering wheel motion system can make the dual steering wheel motion system change lanes, turn and other actions without turning the front of the car. It has strong flexibility, flexible motion and rich application scenarios. The dual rudder wheel motion system can realize 360°rotation function, and can also realize universal lateral movement, with high flexibility and precise running accuracy. However, the high coupling and non-linearity of the dual rudder wheels makes the control of the dual rudder wheel motion system more complicated than that of the differential wheel motion system, requiring more constraints, and has the characteristics of nonlinearity and uncertainty.

Contents of the invention

The purpose of the present invention is to provide an improved motion control method of the dual-rudder-wheel autonomous mobile device, thereby simplifying the control of the dual-rudder-wheel autonomous mobile device.

According to a first aspect of the present invention, a kind of motion control method of dual rudder wheel type autonomous mobile equipment is provided, wherein, the motion control method comprises the following steps:

Step S1, obtaining the planned path trajectory;

Step S2, based on the differential motion model and the planned path trajectory, determine a series of linear velocity v, angular velocity ω, and rudder angle Ω of the autonomous mobile device corresponding to the segmented path trajectory, where the rudder angle Ω represents the autonomous mobile device. the angle between the direction of motion and the longitudinal axis of the autonomous mobile device; and

Step S3: Make the autonomous mobile device move at the determined linear velocity v, angular velocity ω and rudder angle Ω.

In an exemplary embodiment, step S3 includes the following sub-steps:

Sub-step S31, based on the linear velocity v, angular velocity ω and rudder angle Ω of the autonomous mobile device, determine the control parameters of each steering wheel of the dual steering wheel autonomous mobile device; and

Sub-step S32, operating the dual steering wheel mechanism of the dual steering wheel autonomous mobile device according to the control parameters of each steering wheel.

In an exemplary embodiment, the rudder angle Ω is set to be selected from 0° and 90°.

In an exemplary embodiment, the dual steering wheel autonomous mobile device includes a first steering wheel located at the front left and a second steering wheel located at the rear right.

In an exemplary embodiment, in step S3:

When the rudder angle Ω is 0°, the control parameters of each steering wheel are determined according to the following formula:

Among them, L and B represent the wheelbase and wheel base of the autonomous mobile device respectively, r is the wheel radius, v _lf , ω _lf and δ _lf represent the linear velocity, angular velocity and relative motion direction of the first steering wheel respectively Declination angle, v _rr , ω _rr and δ _rr respectively represent the linear velocity, angular velocity and deflection angle relative to the direction of motion of the autonomous mobile device of the second steering wheel, v _lf =ω _lf ·r, v _rr =ω _rr ·r; and / or

When the rudder angle Ω is 90°, the control parameters of each steering wheel are determined according to the following formula:

Among them, L and B represent the wheelbase and wheel base of the autonomous mobile device respectively, r is the wheel radius, v _lf , ω _lf and δ _lf represent the linear velocity, angular velocity and relative motion direction of the first steering wheel respectively The deflection angle, v _rr , ω _rr and δ _rr represent the linear velocity, angular velocity and deflection angle of the second steering wheel relative to the movement direction of the autonomous mobile device, v _lf =ω _lf ·r, v _rr =ω _rr ·r.

In an exemplary embodiment, in each path trajectory segment, the autonomous mobile device moves along a straight line.

In an exemplary embodiment, in step S1, a differential motion model satisfying the following formula is adopted:

Among them, x _k , y _k and θ _k represent the position coordinates and attitude angles of the k+1th path track point of the autonomous mobile device in the path trajectory, and Δt represents the movement of the autonomous mobile device from the k+1th path track point to The time taken by the k+2th path track point, the obtained linear velocity v and angular velocity ω respectively represent the path track segment between the k+1th path track point and the k+2th path track point of the autonomous mobile device The linear and angular velocities in .

In an exemplary embodiment, step S1 includes:

Planning the path trajectory of the autonomous mobile device based on the origin, destination and mission of the autonomous mobile device; and/or

The rudder angle Ω is determined according to at least one of the task of the autonomous mobile device, the traversable space of the autonomous mobile device, and the bending degree of the path trajectory.

In an exemplary embodiment, when the task of the autonomous mobile device does not include a lateral demand, the rudder angle Ω of the corresponding path trajectory segment is 0°; when the task of the autonomous mobile device contains a lateral demand, the corresponding path trajectory The rudder angle Ω of the segment is 90°.

According to a second aspect of the present invention there is provided a computer program product comprising computer program instructions, wherein when said computer program instructions are executed by one or more processors, said processors are capable of performing Invented motion control method.

According to a third aspect of the present invention, there is provided a motion control system for a dual steering wheel type autonomous mobile device, wherein the motion control system includes a dual steering wheel mechanism and at least one controller for controlling the operation of the dual steering wheel mechanism, The dual steering wheel mechanism and the controller are configured to be able to execute the motion control method according to the present invention.

The positive effect of the present invention is that by using the differential motion model to control the motion of the dual-rudder-wheel autonomous mobile device, the motion model of the dual-rudder-wheel autonomous mobile device can be simplified, thereby reducing the difficulty of control. In addition, in engineering applications, the control of the differential robot and the dual-rudder robot is unified as much as possible, which simplifies the complexity of developing from the differential robot to the dual-rudder robot.

Description of drawings

Hereinafter, the principles, features and advantages of the present invention can be better understood by describing the present invention in more detail with reference to the accompanying drawings. The attached drawings include:

Fig. 1 shows a schematic diagram of a dual steering wheel type autonomous mobile device according to an exemplary embodiment of the present invention;

Fig. 2 schematically shows a motion control method of an autonomous mobile device according to an exemplary embodiment of the present invention;

Figure 3A and Figure 3B respectively show two path trajectories according to the autonomous mobile device shown in Figure 2;

Fig. 4 schematically illustrates determining the rudder angle according to the task of the autonomous mobile device in an exemplary embodiment of the present invention;

Fig. 5 schematically illustrates determining the rudder angle according to the navigable space of the autonomous mobile device in an exemplary embodiment of the present invention; and

Fig. 6 schematically shows the determination of the rudder angle according to the bending degree of the path trajectory of the autonomous mobile device in an exemplary embodiment of the present invention.

detailed description

In order to make the technical problems, technical solutions and beneficial technical effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and a number of exemplary embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, rather than to limit the protection scope of the present invention.

The present invention is applicable to autonomous mobile equipment, which can be any mechanical equipment capable of autonomously moving in space, such as automatic guided vehicles (AGV), drones, robots, and the like. For example, an autonomous mobile device can be a storage robot, a cleaning robot, a family escort robot, a welcome robot, etc. The invention is especially suitable for the dual steering wheel type autonomous mobile equipment. Below, the basic principle of the present invention will be described by taking the AGV 10 as an example.

Fig. 1 shows a schematic diagram of a dual steering wheel type autonomous mobile device, here an AGV 10, according to an exemplary embodiment of the present invention. The AGV 10 is provided with a dual steering wheel kinematic mechanism and a controller 14 for controlling the operation of the dual steering wheel kinematic mechanism. The double steering wheel movement mechanism can have two steering wheels installed diagonally: a first steering wheel 121 and a second steering wheel 122, wherein the first steering wheel 121 is located at the left front, and the second steering wheel 122 is located at the right rear. It should be understood that the dual steering wheel kinematics could also have two steering wheels located front right and rear left. In addition, the double rudder wheel movement mechanism may also have two rudder wheels installed on the central axis or two rudder wheels installed on the same side.

The dual rudder wheel autonomous mobile device can realize 360°rotational motion, and can also realize universal lateral movement, which has high flexibility and high running precision. However, the motion control model of the dual rudder wheel autonomous mobile device is complex and difficult to control.

As shown in Figure 1, the AGV 10 moves with a linear velocity v and an angular velocity ω, and the body yaw angle (that is, the angle between the longitudinal axis l of the AGV 10 and the positive direction of the X-axis of the global coordinate system, usually taking the positive counterclockwise direction) is Ψ . The rotation angles of the first steering wheel 121 and the second steering wheel 122 relative to the longitudinal axis l of the AGV 10 are δ′ _lf and δ′ _rr , respectively. The equivalent rotation angles of the center points of the front and rear axles of the AGV 10 are δ _f and δ _r respectively, and the side slip angle of the center point is β. In the state shown in Figure 1, the steering center of the AGV 10 is located at point C, and k represents the distance between the projection (vertical foot) of the steering center C on the longitudinal axis l of the autonomous mobile device and the center point (centroid) of the autonomous mobile device The offset distance between them, R represents the turning radius corresponding to the turning center C of the AGV 10. The wheelbase L and wheelbase B of the AGV 10 are known, and a=b=L/2. The radii of the wheels of the AGV 10 are equal, ie r _lf =r _rr =r. It should be understood that, herein, the longitudinal axis l, the wheel base L and the wheel base B are inherent features of the AGV 10 , which do not vary with the direction of movement of the AGV 10 .

By controlling the rotation angles _δ′lf and _δ′rr of the two steering wheels of the AGV 10, the following formula (1) can be used to determine the equivalent rotation angles _δf and δr of the center points of the front and rear axles, as well as the steering radius _R and the offset distance k:

When the AGV 10 is in motion, a vertical foot motion model as shown in the following formula (2) can be established:

in,

and

Respectively represent the abscissa, ordinate and yaw angle of the k+1th position of the vertical foot,

and

Respectively represent the abscissa, ordinate and yaw angle of the k+2th position of the vertical foot, and Δt represents the time it takes for the autonomous mobile device to move from the k+1th path track point to the k+2th path track point.

At the k+2th position and the k+1th position, the position between the vertical foot of the AGV 10 and the center point satisfies the following constraints:

Putting the above two formulas into formula (2), the motion model of the center point of the dual rudder wheel motion mechanism can be obtained as follows:

Among them, the angular velocity ω of AGV 10 satisfies the following constraints:

Usually, based on the above-mentioned central point motion model, for example, the linear velocity v, angular velocity ω, and linear velocity direction of the AGV 10 can be determined, as well as the speed (linear velocity or angular velocity of the steering wheel) and rotation angle of each steering wheel can be determined, so that the AGV 10 can follow the planned path trajectory movement.

As mentioned above, the dual steering wheel motion model is more complicated. Especially compared with the differential motion model, the dual steering wheel motion model involves more variables, which makes the control algorithm based on the dual steering wheel motion model complex and difficult to control.

For this reason, the present invention proposes based on the differential motion model and the path track of planning, determine a series of linear velocity v, angular velocity ω and rudder angle Ω corresponding to the path track of segment of autonomous mobile equipment, wherein, rudder angle Ω represents The angle between the direction of motion of the autonomous mobile device and the direction of the front of the vehicle (longitudinal axis l). As a result, the motion model of the dual steering wheel AGV 10 can be simplified, thereby reducing the difficulty of control. In addition, in engineering applications, the control of the differential robot and the dual-rudder robot is unified as much as possible, which simplifies the complexity of developing from the differential robot to the dual-rudder robot. In the same path segment, the rudder angle Ω remains unchanged. However, in different path trajectories, the rudder angle Ω may be different. The switching of the rudder angle Ω can be realized by changing the steering wheel's rotation angle in situ.

Fig. 2 schematically shows a motion control method of a double steering wheel AGV 10 according to an exemplary embodiment of the present invention. The motion control method includes the steps of:

Step S1, obtaining the planned path trajectory;

Step S2, based on the differential motion model and the planned path trajectory, determine a series of linear velocity v, angular velocity ω, and rudder angle Ω of the autonomous mobile device corresponding to the segmented path trajectory, where the rudder angle Ω represents the autonomous mobile device. The angle between the direction of motion and the direction of the vehicle head (longitudinal axis l), the rudder angle Ω remains constant in the same path trajectory segment; and

Through the motion control method, the control difficulty of the double steering wheel AGV 10 can be reduced.

Step S3 may include the following sub-steps:

The control parameters include, for example, the speed of the first steering wheel 121 (linear velocity v _lf and/or angular velocity ω _lf ) and the deflection angle δ _lf relative to the direction of motion of the autonomous mobile device, and the speed of the second steering wheel 122 (linear velocity v _rr and/or angular velocity ω _rr ) and declination δ _rr relative to the direction of motion of the autonomous mobile device. The sub-step S32 may include, for example: the controller 1 sends corresponding control signals to a driving mechanism for driving each steering wheel, such as a motor, according to the control parameters of each steering wheel.

In an exemplary embodiment, the rudder angle Ω is set to be selected from 0° and 90°. In other words, the rudder angle Ω can only be equal to 0° or 90°, and can be switched between 0° and 90°. In this way, the control algorithm of the AGV 10 can be further simplified, and the rudder angle switching frequency of the AGV 10 can be reduced. The motion of an autonomous mobile device in a plane can be decomposed into two sub-motions that are orthogonal to each other. When using the differential speed model to control the dual steering wheel mode, in order to make the AGV 10 move in any direction on the plane, the motion can be decomposed into the motion along the direction of the AGV 10 head and the motion perpendicular to the direction of the AGV 10 head. The movement along the front direction of AGV 10 can be controlled by setting the rudder angle Ω to 0° and according to the differential motion model. The movement along the direction perpendicular to the front of the AGV 10 can be controlled by setting the rudder angle Ω to 90°, and then according to the differential motion model.

3A and 3B respectively show two path trajectories of the AGV 10 according to this exemplary embodiment. Figure 3A shows that the rudder angle Ω of the AGV 10 is set to 0°, that is, in the entire path trajectory, the direction of motion of the AGV 10 is always along the direction of the front of the vehicle. In this case, the linear velocity and angular velocity of the AGV 10 can be directly determined according to the differential motion model. Figure 3A shows that the rudder angle Ω of the AGV 10 is set to 90°, that is, in the entire path trajectory, the direction of motion of the AGV 10 is always at an angle of 90° relative to the direction of the vehicle head. At the starting point of the path trajectory, the AGV 10 realizes the switching of the rudder angle by turning the rudder wheel in situ by a certain angle (in this case, 90°). In this case, the linear velocity and angular velocity of the AGV 10 can be determined according to the differential motion model after deflecting 90°.

Returning to Figure 1 below, when the rudder angle Ω is 0°, in order to use the differential speed model to control the movement of the dual steering wheel AGV10, the constraint of k=0 (equivalent to β=0) needs to be satisfied, and the formula (1) can be obtained :

That is, as long as the sum of the equivalent rotation angles of the front and rear axles of AGV 10 is 0 (δ _f =-δ _r ), or when the rotation angles of the two steering wheels obey the following constraints, k=0 can be made:

Thus, the motion model of the dual rudder wheel AGV 10 can be simplified to a differential speed model:

At this time, the speed of AGV 10 satisfies:

The relationship between the angular velocity of AGV 10 and the angular velocity of each steering wheel can be simplified as:

The deflection angle of the two steering wheels relative to the direction of motion of the autonomous mobile device can be determined by:

Therefore, in step S3, when the rudder angle Ω is 0°, the control parameters of each steering wheel can be determined according to the following formula:

Among them, L and B represent the wheelbase and wheel base of the autonomous mobile device, r is the wheel radius, and v _lf , ω _lf and δ _lf represent the linear velocity, angular velocity and motion direction of the first steering wheel 121 relative to the autonomous mobile device v _rr , ω _rr and δ _rr respectively represent the linear velocity, angular velocity and the deflection angle relative to the direction of motion of the autonomous mobile device of the second steering wheel 122, v _lf =ω _lf ·r, v _rr =ω _rr · r.

Similarly, when the rudder angle Ω is 90°, it is equivalent to exchanging the wheelbase B and the wheelbase L of the AGV 10. Therefore, in step S3, when the rudder angle Ω is 90°, the control parameters of each steering wheel can be determined according to the following formula:

It should be understood that in other embodiments, the rudder angle Ω can also be set to other angles, for example, be set to be selected from 0°, 60° and 120°. In this way, it is possible to decompose the movement of the autonomous mobile device in the plane into three partial movements at 60° to each other.

Optionally, the rudder angle Ω is set to be selected from two angles that differ from each other by 90°, for example 45° and 135° degrees. Thus, it is possible to decompose the motion of the autonomous mobile device in the plane into two sub-motions orthogonal to each other, wherein the two sub-motions can be realized according to the differential motion model.

Optionally, in each path segment, the AGV 10 moves along a straight line. When the AGV 10 moves along a straight line, its angular velocity ω=0. Therefore, δ _lf =δ _rr =0, v _lf =v _rr =v, ω _lf =ω _rr . Thus, the control algorithm can be further simplified.

In step S1, the differential motion model adopted may be a tangent model, a secant model or an arc model.

For example, in an exemplary embodiment, a differential motion model satisfying the following formula is adopted in step S1:

Among them, x _k , y _k and θ _k represent the position coordinates and attitude angles of the k+1th path track point of the autonomous mobile device in the path trajectory, and Δt represents the movement of the autonomous mobile device from the k+1th path track point to The time taken by the k+2th path track point, the obtained linear velocity v and angular velocity ω respectively represent the path track segment between the k+1th path track point and the k+2th path track point of the autonomous mobile device The linear and angular velocities in . It should be understood that when applying the differential motion model represented by the above formula, the numerical changes of various variables caused by switching the rudder angle Ω should be taken into account. For example, when the rudder angle Ω is switched from 0° to 90°, the vehicle coordinate system relative to the AGV is rotated by 90°, so that the attitude angle of the AGV will increase by 90° even though the AGV itself remains stationary.

In an exemplary embodiment, step S1 includes planning a path trajectory of the autonomous mobile device according to the origin, destination and mission of the autonomous mobile device. Therefore, the path trajectory of the autonomous mobile device can be reasonably planned, so as to simplify the motion model of the autonomous mobile device while still meeting the motion accuracy requirements of the autonomous mobile device. In particular, in step S1, based on the differential motion model, the path trajectory of the autonomous mobile device is planned according to the origin, destination and mission of the autonomous mobile device. For example, if due to the limitation of the passable space (the space available for AGV to pass), the path trajectory of the AGV's differential motion at the current rudder angle Ω will be very complicated or even unable to reach the target point, then the path trajectory can be reasonable Segmentation, use the movement mode along the direction of the front of the vehicle and the movement mode along the direction perpendicular to the front of the vehicle to control separately in different path segments.

Tasks for autonomous mobile devices may include side docking, side driving, or side obstacle avoidance, among others. It should be understood that "lateral" is relative to the inherent orientation of the AGV 10, which does not change with the direction of movement of the AGV 10. The lateral direction may include a direction perpendicular to the longitudinal axis 1 of the AGV 10, and also include a direction with an angle greater than 30°, especially greater than 45°, especially greater than 75° relative to the longitudinal axis 1.

Alternatively or additionally, step S1 includes determining the rudder angle Ω according to at least one of the task of the autonomous mobile device, the traversable space of the autonomous mobile device and the bending degree of the path trajectory.

Figure 4 schematically shows the determination of the rudder angle Ω according to the task of the AGV 10. When the AGV 10 needs to perform lateral docking tasks with other equipment 20, such as transmission equipment or shelves, the rudder angle Ω is set to 90° (as shown by the dotted line). As a result, docking accuracy can be improved. After the AGV 10 is docked with other equipment 20, for example, automatic handling of heavy materials in storage or production lines, shelf handling, automatic storage systems, and automatic loading and unloading of roller transmissions can be realized.

Fig. 5 schematically illustrates determining the rudder angle Ω according to the traversable space of the AGV 10. For example, when the AGV 10 needs to pass through a narrow passage, such as a narrow passage between two shelves, the rudder angle Ω can be set to 0° (as shown by the dotted line). It will be appreciated that the length of the AGV 10 along the longitudinal axis l is generally greater than the width perpendicular to the longitudinal axis l. Therefore, compared with the case where the rudder angle Ω is equal to 90°, when the AGV 10 moves along a straight line with a rudder angle Ω equal to 0°, the required channel width is narrower. If the width of the channel is greater than the width of the AGV 10 but less than the length of the AGV 10, then the AGV 10 cannot enter or pass through the channel with a rudder angle Ω equal to 90°, so the AGV 10 needs to switch to a motion with a rudder angle Ω equal to 0° mode to enter or pass through the channel. Of course, when the width of the passage is slightly greater than the length of the AGV 10, the AGV 10 can also be switched to a motion mode in which the rudder angle Ω is equal to 0° so as to enter or pass through the passage, thereby improving the safety of the movement. In addition, if the AGV 10 is configured so that the length along the longitudinal axis l is smaller than the width perpendicular to the longitudinal axis l, the rudder angle Ω can be set to 90° when the AGV 10 needs to pass through a narrow passage.

Fig. 6 schematically shows that the rudder angle Ω is determined according to the bending degree of the path trajectory of the AGV 10. When the path trajectory of AGV 10 includes turning requirements, the rudder angle Ω can be switched. Then, the AGV 10 can move with the switched rudder angle Ω, thereby realizing turning.

Optionally, when the task of the autonomous mobile device does not contain lateral demands, the rudder angle Ω of the corresponding path trajectory segment is 0°; when the task of the autonomous mobile device contains lateral demands, the rudder angle of the corresponding path trajectory segment Ω is 90°. In other words, the autonomous mobile device can preferentially move in a mode with a rudder angle Ω of 0°, and switch the rudder angle Ω to 90° only when the task of the autonomous mobile device includes lateral demands.

The present invention also relates to a motion control system for a dual steering wheel autonomous mobile device, wherein the motion control system includes a dual steering wheel mechanism and at least one controller for controlling the operation of the dual steering wheel mechanism, the dual steering wheel mechanism and the controller It is arranged to be able to execute the motion control method according to the present invention. The at least one controller may be a controller mounted on a dual steering wheel autonomous mobile device. Alternatively, the at least one controller may also include a first controller installed on the dual steering wheel autonomous mobile device and a second controller installed in the dispatch center, and the first controller and the second controller may interact with each other. communication, so as to execute the motion control method according to the present invention in cooperation with each other. For example, path planning for the autonomous mobile device can be performed in the second controller. Then, the second controller sends the planned path trajectory information to the first controller. The first controller may perform subsequent steps (such as steps S2 and S3 ) after receiving the planned path trajectory.

It should be understood that the features and advantages described above for the motion control method of the dual steering wheel autonomous mobile device are also applicable to the motion control system of the dual steering wheel autonomous mobile device.

Furthermore, the invention also relates to a computer program product comprising computer program instructions which, when executed by one or more processors, enable said processors to perform the motion control method according to the invention.

In the present invention, the computer program product can be stored in a computer-readable storage medium. The computer-readable storage medium can include, for example, a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD card, flash card (Flash Card), at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage device. The processor 10 can be a central processing unit (Central Processing Unit, CPU), and can also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf Field-Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor or the like.

While specific embodiments of the invention have been described in detail, these have been presented for purposes of illustration only and should not be construed as limiting the scope of the invention. Various alternatives, changes and modifications can be devised without departing from the spirit and scope of the invention.

List of reference signs

10 AGVs

121 First steering wheel

122 second steering wheel

14 controller

20 additional equipment

Claims

A motion control method for a dual rudder wheel type autonomous mobile device, wherein the motion control method includes the following steps:

Step S1, obtaining the planned path trajectory;

Step S2, based on the differential motion model and the planned path trajectory, determine a series of linear velocity v, angular velocity ω, and rudder angle Ω of the autonomous mobile device corresponding to the segmented path trajectory, where the rudder angle Ω represents the autonomous mobile device. the angle between the direction of motion and the longitudinal axis of the autonomous mobile device; and

Step S3: Make the autonomous mobile device move at the determined linear velocity v, angular velocity ω and rudder angle Ω.
The motion control method according to claim 1, wherein step S3 comprises the following sub-steps:

Sub-step S31, based on the linear velocity v, angular velocity ω and rudder angle Ω of the autonomous mobile device, determine the control parameters of each steering wheel of the dual steering wheel autonomous mobile device; and

Sub-step S32, operating the dual steering wheel mechanism of the dual steering wheel autonomous mobile device according to the control parameters of each steering wheel.
The motion control method according to claim 1 or 2, wherein the rudder angle Ω is set to be selected from 0° and 90°.
The motion control method according to claim 3, wherein the dual steering wheel autonomous mobile device includes a first steering wheel located at the left front and a second steering wheel located at the right rear.
The motion control method according to claim 4, wherein, in step S3:

When the rudder angle Ω is 0°, the control parameters of each steering wheel are determined according to the following formula:

Among them, L and B represent the wheelbase and wheel base of the autonomous mobile device respectively, r is the wheel radius, v lf , ω lf and δ lf represent the linear velocity, angular velocity and relative motion direction of the first steering wheel respectively Declination angle, v rr , ω rr and δ rr respectively represent the linear velocity, angular velocity and deflection angle relative to the direction of motion of the autonomous mobile device of the second steering wheel, v lf =ω lf ·r, v rr =ω rr ·r; and / or

When the rudder angle Ω is 90°, the control parameters of each steering wheel are determined according to the following formula:

Among them, L and B represent the wheelbase and wheel base of the autonomous mobile device respectively, r is the wheel radius, v lf , ω lf and δ lf represent the linear velocity, angular velocity and relative motion direction of the first steering wheel respectively The deflection angle, v rr , ω rr and δ rr represent the linear velocity, angular velocity and deflection angle of the second steering wheel relative to the movement direction of the autonomous mobile device, v lf =ω lf ·r, v rr =ω rr ·r.
The motion control method according to any one of claims 1-5, wherein, in step S1, a differential motion model satisfying the following formula is used:

Among them, x k , y k and θ k represent the position coordinates and attitude angles of the k+1th path track point of the autonomous mobile device in the path trajectory, and Δt represents the movement of the autonomous mobile device from the k+1th path track point to The time taken by the k+2th path track point, the obtained linear velocity v and angular velocity ω respectively represent the path track segment between the k+1th path track point and the k+2th path track point of the autonomous mobile device The linear and angular velocities in .
The motion control method according to any one of claims 1-6, wherein step S1 comprises:

Planning the path trajectory of the autonomous mobile device based on the origin, destination and mission of the autonomous mobile device; and/or

The rudder angle Ω is determined according to at least one of the task of the autonomous mobile device, the traversable space of the autonomous mobile device, and the bending degree of the path track.
The motion control method according to claim 7, wherein, when the task of the autonomous mobile device does not include a lateral demand, the rudder angle Ω of the corresponding path trajectory segment is 0°; when the task of the autonomous mobile device includes a lateral demand , the rudder angle Ω of the corresponding path trajectory segment is 90°.
A computer program product, in particular a computer readable storage medium, comprising computer program instructions, wherein, when said computer program instructions are executed by one or more processors, said processors are capable of performing the - The motion control method according to any one of 8.
A motion control system for a dual steering wheel type autonomous mobile device, wherein the motion control system includes a dual steering wheel mechanism and at least one controller for controlling the operation of the dual steering wheel mechanism, and the dual steering wheel mechanism and the controller are configured to be able to execute The motion control method according to any one of claims 1-8.