CN114510040A - Time-sharing coordination control method for wheeled mobile robot group terminal - Google Patents

Abstract

The invention discloses a method for coordinating and controlling the time of a wheeled mobile robot group through a terminal of a target position in a time-sharing manner, which comprises the following steps: constructing a relative kinematics model of the wheeled mobile robot and the target position; estimating the terminal time of each wheeled mobile robot which is expected to pass through the target position according to the initial state, and distributing the sequence of each wheeled mobile robot in the group passing through the target position based on the terminal time; constructing acceleration control of each wheeled mobile robot perpendicular to the sight line by utilizing non-smooth control, so that the lead angle is converged to zero at fixed time; designing a residual time estimation formula of each wheeled mobile robot passing through a target position, constructing a standard passing error based on information interaction by combining a distribution sequence, and enabling the standard passing error to be converged to zero in limited time by utilizing non-smooth control; the acceleration control along the sight line and the direction vertical to the sight line is converted into tangential and normal acceleration control of the wheeled mobile robot. The designed control method realizes that the wheeled mobile robot group passes through the appointed target position in a coordinated and time-sharing manner according to the appointed passing time interval.

Description

A time-sharing coordinated control method for wheeled mobile robot group terminals

Technical field:

The invention relates to the technical field of multi-agent control, in particular, to a time-sharing coordinated control method for a wheeled mobile robot group terminal.

Background technique:

Using multi-agent collaborative control methods to achieve convergence or formation of robot groups such as unmanned vehicle queues and drone swarms, there have been related algorithms and theoretical research at this stage. However, due to the influence of the actual environment, in some cases, the robot group needs to pass the target position or other terminal time constraints at the specified time interval, such as the pipeline resource allocation problem, each robot needs to load goods at the specified resource allocation site, To get an order or update a route, due to factors such as the limited processing capacity of the site, the robot group needs to pass through the site in batches to minimize waiting and overall distribution time.

At present, there are few literatures about time-sharing coordinated control of terminal time, mainly focusing on the saturation attack problem in the military field. Usually, the proportional guidance method is used to estimate the remaining time for the missile to hit the target, and it is used as a coordination variable to achieve consistency, such as the prior art [1] (see Jialing Zhou and Jianying Yang. Distributed Guidance LawDesign for Cooperative Simultaneous Attacks with Multiple Missiles [J]. Journal of Guidance, Control, and Dynamics, 2016, 39(10): 2439-2447.); or specify a specific time so that the missile arrives at a specified location at a specified time, as in the prior art [2] (see Jun Zhou, Yang Wang, and BinZhao. Impact-Time-Control Guidance Law for Missile with Time-Varying Velocity [J]. Mathematical Problems in Engineering, 2016, 4: 1-14). The existing related terminal time coordination control technologies are mostly researches on terminal time consistency, and no research on terminal time time sharing coordination control for multi-moving body time-sharing passing through the target position has been found. Although the technology that the missile hits the target at the specified time can be applied to the terminal time-sharing task, however, the terminal time of each moving body needs to be specified in advance, resulting in the lack of real-time coordination and robustness, and it is difficult to resist environmental interference.

This patent proposes a terminal time coordination control method for an underdriven wheeled mobile robot to pass the target position in a time-sharing manner, without specifying the terminal time of each wheeled mobile robot to pass the target position in advance, and the control algorithm has real-time coordination and robustness. In addition, the research object of this patent is the under-driven wheeled mobile robot, which cannot retreat during the movement process, cannot be controlled in all directions, and the speed and direction cannot be changed abruptly; the wheeled mobile robot group is the target terminal time-sharing coordinated control algorithm It can be applied to tasks such as groups of freight robots passing through stations in batches, and unmanned vehicles coordinating time-sharing through ramps, etc., and has good practical application value.

Invention content:

In view of the deficiencies of the prior art, the present invention provides a time-sharing coordination control method for a group terminal of a wheeled mobile robot. Given a target position and a passing interval, the robot group can automatically determine the passing order and coordinate the time-sharing passing target. Location.

The concrete technical scheme of the present invention is as follows:

(1) Build the relative kinematics model of the wheeled mobile robot and the target position.

(2) According to the kinematic model in step (1), establish the estimation of the terminal time of each wheeled mobile robot at the initial moment, and based on this, determine the order in which each wheeled mobile robot in the group passes through the target position.

(3) According to the kinematics model in step (1), the non-smooth control is used to construct the acceleration control perpendicular to the line of sight, so that the lead angle of each wheeled mobile robot in the group or the velocity component perpendicular to the line of sight can be achieved within a fixed time. converges to zero.

(4) According to the kinematic model in step (1), the remaining time estimation formula of each wheeled mobile robot is designed, and the standard passing error based on information interaction is constructed in combination with the allocation order. Constructing the acceleration control along the line of sight with non-smooth control can make the standard passing error converge to zero in a fixed time.

(5) According to the communication network structure and the passing situation of the wheeled mobile robot group and the acceleration control scheme along the line of sight and perpendicular to the line of sight designed in steps (3) and (4), construct the tangential acceleration of the wheeled mobile robot and the Normal acceleration control.

Further, the wheeled mobile robot in step (1) and the specific construction method of the kinematics model by the relative positional relationship of the target position are: assuming that the group is composed of N robots, the wheeled mobile robot i under the inertial coordinate system, ( The kinematic model of i=1,...,N) is specifically:

Where (x _i , y _i ) represents the position coordinates of the robot's center of mass, θ _i is the heading angle of the robot i (that is, the angle between the speed direction and the x-axis, and the counterclockwise direction is the positive direction), and vi represents the speed of the robot _i . , ω _i the heading angular rate of robot i.

Assuming that the coordinates of the target position are (x ^* , y ^* ), the kinematic model of the relative positional relationship between the wheeled mobile robot i and the passing target position is:

表示机器人与通过目标间的距离，λ_i＝atan2(x^*-x，y^*-y)表示视线角，φ_i表示前置角，a_t，i与a_n，i分别表示机器人i的切向加速度与法向加速度(即机器人加速度沿着速度方向、垂直于速度方向的加速度分量)。in

represents the distance between the robot and the passing target, λ _i = atan2(x ^* -x, y ^* -y) represents the line of sight angle, φ _i represents the lead angle, at _{, i} and an _{, i} represent the cutting angle of the robot i respectively Toward acceleration and normal acceleration (that is, the acceleration component of the robot acceleration along the velocity direction and perpendicular to the velocity direction).

According to the kinematic model of the relative position relationship, the relationship model between the relative position and the control input can be further established:

where ur _{, i} = _{at, i} cos φ _i -a _{n, i} sin φ _i , u _{λ, i} = _{at t, i} sin φ _i +a _{n, i} cos φ _i represent the robot along the line of sight direction and vertical acceleration in the direction of sight.

In step (2), it is estimated that the time to arrive at the passing location determines the order in which the robot group passes through the target. Specifically:

(2-1) Number the N robots in the group l ₁ , l ₂ , . . . , l _N in any order.

(2-2) Estimating the arrival time of each mobile robot in the group according to the initial motion state

where the subscript l∈{l ₁ ,...,l _N } denotes the mobile robot numbered l, and t ₀ denotes the initial moment.

设定机器人群组通过目标的顺序记为重新编号后的次序。(2-3) Arrange the estimated arrival times in ascending order and renumber the robots 1, 2, ..., N to satisfy

Set the order in which the robot group passes through the targets as the renumbered order.

In step (3), the non-smooth control is used to establish the acceleration control scheme of the wheeled mobile robot i perpendicular to the line of sight. Specifically:

where α _{λ, i} , β _{λ, i} , p _{λ, i} , q _{λ, i} >0 are constant parameters and satisfy 0<p _{λ, i} <1<q _λ,i , and the function sgn ^α (·) is specifically

sgn ^α (x)=|x| ^α sign(x), where sign(·) is a sign function.

In step (4), the non-smooth control is used to establish the acceleration control of the wheeled mobile robot i along the line of sight, so that the standard passing error can converge to zero within a fixed time, and the control is specifically:

(4-1) Build network communication connections in the robot group, so that the topology structure of the communication connections contains a directed spanning tree.

(4-2) Calculate the standard passing error ξ _i using the communication network

Among them, δ represents the time interval for passing the target position of the adjacent robots, a _ij represents the elements of the adjacency matrix induced by the communication topology, that is, if the robot i can accept the information sent by the robot j, then a _ij > 0, otherwise a _ij = 0. In particular, a _ii =0.

如果轮式移动机器人i未通过目标位置，则轮式移动机器人i的预计剩余时间具体可表示为：(4-3) Setting tolerance

If the wheeled mobile robot i fails to pass the target position, the estimated remaining time of the wheeled mobile robot i can be specifically expressed as:

r(t)＞ε.此时令

为机器人通过目标位置后的时间计数：If the wheeled mobile robot i has reached the target position or the distance from the target position is less than ε, and the passing time is T _i , that is, there is T _i such that r(T _i )≤ε, and for

r(t)>ε. This time

Count the time after the robot has passed the target position:

t _go,i =T _i -t.

(4-4) Determine the acceleration control of robot i along the line of sight

为轮式移动机器人i的预计剩余时间，α_r，i，β_r，i，p_r，i，q_r，i＞0为常参数并满足0＜p_r，i＜1＜q_r，i。in

is the estimated remaining time of the wheeled mobile robot i, α _{r, i} , β _{r, i} , _{pr, i} , q _{r, i} >0 are constant parameters and satisfy 0< _{pr, i} <1<q _r,i .

In step (5), the acceleration and angular acceleration control method of the wheeled mobile robot i is specifically:

(5-1) The acceleration and angular acceleration control of the wheeled mobile robot i are expressed as follows:

a _{t, i} = ur _{, i} cos φ _i +u _{λ, i} sin φ _i

a _n,i =-ur _,i sin φ _i +u _λ,i cos φ _i .

(5-2) If the wheeled mobile robot has saturation constraints such as the upper limit of speed and the upper limit of acceleration, when the acceleration control designed in (5) exceeds the constraints, the corresponding saturation value is selected as the control input.

则需事先让所有机器人调整运动方向至

(5-3) The initial speed direction of the robot in the group forms an obtuse or right angle with the angle of sight, that is,

You need to make all robots adjust the movement direction to

Compared with the prior art, the beneficial effects of the present invention are:

The invention provides a time-sharing coordination control method for a group terminal of a wheeled mobile robot. Given a target position and a passing interval, the robot group can automatically determine the passing order and coordinate the time-sharing passing through the target position.

The control method of the present invention can meet the requirement of time-sharing coordination for the under-driven wheeled mobile robot. This method utilizes the communication network and does not need to specify the time and order of passing through the target position in advance, which increases the environmental adaptability and ensures that the passing time interval of the two robots meets the requirements. set a wider range of initial values.

Description of drawings

Fig. 1 is the flow chart of the wheeled mobile robot group time-sharing coordination control method of the present invention;

2 is a schematic diagram of the angular relationship between the wheeled mobile robot of the present invention and the passing target position;

Fig. 3 is the wheeled mobile robot group communication network topology structure of the present invention;

4 is a schematic diagram of the motion trajectory result of the wheeled mobile robot group simulated by the present invention;

5 is a schematic diagram of the variation of the distance between each wheeled mobile robot and the target position point simulated by the present invention with time;

6 is a schematic diagram of the lead angle variation with time of each wheeled mobile robot simulated by the present invention;

Fig. 7 is a schematic diagram showing the variation of the speed of each wheeled mobile robot simulated by the present invention with time;

FIG. 8 is a schematic diagram of the variation of the speed direction with time of each wheeled mobile robot simulated by the present invention;

9 is a schematic diagram of the tangential acceleration of each wheeled mobile robot simulated by the present invention over time;

FIG. 10 is a schematic diagram showing the variation of the normal acceleration with time of each wheeled mobile robot simulated by the present invention.

Detailed ways

The object, technical solution, and advantages of the present invention will be described in further detail below with reference to the accompanying drawings.

At present, there are few researches on time-sharing coordinated control of terminal time, especially the control methods of underactuated wheeled mobile robots as the research object, and such tasks are widely used in production and life. Therefore, a wheeled mobile robot group is constructed. The coordinated control method of component time has practical significance.

Based on the above considerations, the present invention first establishes a kinematic model for constructing the relative positional relationship between the wheeled mobile robot and the passing target position, and then uses a non-smooth control method to construct the acceleration control of the wheeled mobile robot perpendicular to the line of sight, so that the lead angle or vertical Since the speed of the line of sight is reduced to zero within a fixed time, then according to the situation of the robot group passing through the target position and the topology of the communication network in the group, each robot uses non-smooth control to realize the acceleration control of the wheeled mobile robot along the line of sight. , which can make the standard passing error converge to zero in a fixed time, and finally convert the acceleration control along the line of sight and perpendicular to the line of sight into the tangential acceleration and normal acceleration control of the wheeled mobile robot.

Fig. 1 shows that the present invention realizes the time-sharing coordinated control method of wheeled mobile robot group, and the method is specifically executed as follows:

Step 1. Initialize the problem scenario. Adjust the movement direction of each robot in the group so that the lead angles of the robots are all acute angles.

Step 2. Suppose the problem is a time-sharing coordination task of N wheeled mobile robots, and the interval between the passing target positions of two adjacent robots is δ. The _robots are numbered _l1 , _l2 , .

Step 3. Build a kinematic model of the relative positional relationship between the wheeled mobile robot and the target position to be passed.

Step 3-1. As shown in Figure 2, select any point in the plane to construct the inertial coordinate system, then the kinematic model of the wheeled mobile robot i is:

Where (x _i , y _i ) represents the position coordinates of the robot's center of mass, θ _i is the heading angle of the robot i (that is, the angle between the speed direction and the x-axis, and the counterclockwise direction is the positive direction), and vi represents the speed of the robot _i . , ω _i the heading angular rate of robot i.

Step 3-2. According to the constructed inertial coordinate system, determine the target position coordinates (x ^* , y ^* ) that the robot group needs to pass through, and establish a kinematic model of the relative position relationship between the wheeled mobile robot i and the passing target position:

表示机器人与通过目标间的距离，λ_i＝atan2(x^*-x，y^*-y)表示视线角，φ_i表示前置角，a_t，i与a_n，i分别表示机器人i的切向加速度与法向加速度(即机器人加速度沿着速度方向、垂直于速度方向的加速度分量)。in

represents the distance between the robot and the passing target, λ _i = atan2(x ^* -x, y ^* -y) represents the line of sight angle, φ _i represents the lead angle, at _{, i} and an _{, i} represent the cutting angle of the robot i respectively Toward acceleration and normal acceleration (that is, the acceleration component of the robot acceleration along the velocity direction and perpendicular to the velocity direction).

Step 3-3. According to the kinematic model of the relative position relationship, establish a relationship model between the relative position and the control input:

where ur _{, i} = _{at, i} cos φ _i -a _{n, i} sin φ _i , u _{λ, i} = _{at t, i} sin φ _i +a _{n, i} cos φ _i represent the robot along the line of sight direction and vertical acceleration in the direction of sight.

Step 4: Estimating the time required for each robot to pass the target position to determine the order in which the robot group passes the target: Preferably, the estimated arrival time of each mobile robot in the estimated group according to the initial motion state can be designed as:

where the subscript l∈{l ₁ ,...,l _N } denotes the mobile robot numbered l, and t ₀ denotes the initial moment.

设定为机器人群组通过目标的顺序记为重新编号后的次序。Arrange the ETAs in ascending order and renumber the robots 1, 2, ..., N to satisfy

The order in which the robot group passes the target is recorded as the renumbered order.

Step 5 Constructs the acceleration control perpendicular to the line of sight with the non-smooth control. In order to realize that the line-of-sight angular rate or the speed perpendicular to the line of sight tends to zero in a limited time, preferably, the non-smooth control construction wheeled mobile robot i The acceleration control perpendicular to the line of sight can be designed as:

where α _{λ, i} , β _{λ, i} , p _{λ, i} , q _{λ, i} >0 are constant parameters and satisfy 0<p _{λ, i} <1<q _λ,i , and the function sgn ^α (·) is specifically

sgn ^α (x)=|x| ^α sign(x), (6)

where sign(·) is the sign function.

Step 6. Build the acceleration control along the line of sight.

Step 6-1. In order to allow the robot group to pass the target in the specified order and time interval, it is necessary to use the communication network design standard to pass the error:

Among them, δ represents the time interval for passing the target position of the adjacent robots, a _ij represents the elements of the adjacency matrix induced by the communication topology, that is, if the robot i can accept the information sent by the robot j, then a _ij > 0, otherwise a _ij = 0. In particular, a _ii =0.

Step 6-2. If the wheeled mobile robot i fails to pass the target position, the estimated remaining time can be expressed as:

Step 6-3. To increase the environmental adaptability of group time-sharing coordination. Preferably, the acceleration control of the wheeled mobile robot i along the line-of-sight direction is established by using the communication network control and can be designed as:

为轮式移动机器人i的预计剩余时间，a_r，i，β_r，i，p_r，i，q_r，i＞0为常参数并满足0＜p_r，i＜1＜q_r，i。in

is the estimated remaining time of the wheeled mobile robot i, _ar,i ,βr _,i , _pr,i ,qr _,i >0 are constant parameters and satisfy 0< _{pr, i} <1<qr _,i .

Step 5. Convert the acceleration in the line of sight coordinate system into the acceleration and angular acceleration control of the wheeled mobile robot. Specifically, the acceleration and angular acceleration control of the wheeled mobile robot i are expressed as follows:

如果轮式移动机器人i到达过目标位置或距离目标位置已经小于ε，并记通过时刻为T_i，即存在T_i使得r(T_i)≤ε，且对于

r(t)＞ε.此时令

为机器人通过目标位置后的时间计数：Step 6. Update the position and velocity of the wheeled mobile robot. and set the allowable error

If the wheeled mobile robot i has reached the target position or the distance from the target position is less than ε, and the passing time is T _i , that is, there is T _i such that r(T _i )≤ε, and for

r(t)>ε. This time

Count the time after the robot has passed the target position:

t _go,i =T _i -t. (11)

Apply the adjustment made in (11) to the acceleration control (7)-(9) of other wheeled mobile robots along the line of sight.

The following is a simulation verification of a wheeled mobile robot group time-sharing coordinated control method designed by the present invention.

The time-sharing coordination task of 7 wheeled mobile robots is simulated, assuming that the destination coordinate is (0, 0) m, and the time interval δ=3s for passing the destination. The initial parameters of the wheeled mobile robot group are shown in Table 1.

Table 1

object Initial position (m) Speed (m/s) Speed direction (rad) Angular velocity (rad/s) Robot l₁ (27.5, 20.7) 10 -1.3480 0 Robot l₂ (35.4, 5.14) 10 -1.1155 0 Robot l₃ (14.5, 44.1) 10 2.2790 0 Robot l₄ (25.5, 2.98) 10 -1.1882 0 Robot l₅ (44.6, 45.7) 10 -2.8098 0 Robot l₆ (44.8, 65.9) 10 -2.4899 0 Robot l₇ (6.27, 27.8) 10 2.9974 0

After calculation, the estimated passing time of each robot according to the initial value is shown in Table 2.

Table 2

In the simulation experiment, other parameters are selected as follows: α _{r, i} = β _{r, i} = 0.5, α _{λ, i} = β _{λ, i} = 0.5, _{pr, i} = 0.5, q _{r, i} = 2, p _{λ, i} = 0.5, q _{λ, i} = 2, i = 1, ..., 7; ε = 0.1.

The topology of the robot group communication network is shown in Figure 3, and it is assumed that the elements of the adjacency matrix corresponding to the communication edge are all 1, which satisfies the existence of directed paths from robot 1 to other robots, so the topology contains a directed spanning tree.

The simulation results of the time-sharing coordinated control of the wheeled mobile robot group are shown in Table 3 and Figure 4 to Figure 10.

It can be seen from Figure 4 that the wheeled mobile robot group can pass the target position smoothly. Further, it can be seen from Table 3 and Figure 5 that the wheeled mobile robot group reaches the specified target position according to the passing order and passing interval shown in Table 2, and the mean square error does not exceed 0.1s, indicating that the time-sharing coordinated control designed by the patent is used. The effect of the method is excellent.

table 3

object Robot 1 Robot 2 Robot 3 Robot 4 Robot 5 Robot 6 Robot 7 Pass time(s) 2.9288 5.7440 8.9288 11.7440 14.9288 17.8364 20.8826

It can be seen from Figure 6 that the lead angle of each wheeled mobile robot rapidly drops to 0. According to Figure 7, the wheeled mobile robot always maintains a speed greater than zero during the movement process, which meets the requirements, and the wheeled mobile robot is approaching the goal. The ground time speed drops rapidly to zero, and can finally stop at the target position. Figure 8 shows that the velocity direction eventually tends to a constant value, which can ensure that the acceleration control is not singular. Figures 9 and 10 directly show that the acceleration and angular acceleration are bounded, so this control method can be better applied in practice.

Comprehensive simulation experiments show that the wheeled mobile robot group time-sharing coordinated control method designed by the present invention has a good control effect.

The above are only the preferred embodiments of the present invention. It should be pointed out that the above embodiments do not limit the present invention. Various changes and modifications made by the relevant staff within the scope of not departing from the technical idea of the present invention are all within the scope of the present invention. within the scope of protection.

Claims (6)

1. A time-sharing coordination control method for a wheeled mobile robot group terminal is characterized by comprising the following steps:

(1) constructing a relative kinematics model of the wheeled mobile robot and the target position;

(2) according to the kinematics model in the step (1), establishing the estimation of the initial time to the terminal time of each wheeled mobile robot, and determining the sequence of each wheeled mobile robot in the group passing through the target position based on the estimation;

(3) according to the kinematic model in the step (1), utilizing non-smooth control to construct acceleration control perpendicular to the sight line, so that the leading angle of each wheeled mobile robot in the group or the velocity component perpendicular to the sight line can be converged to zero within a fixed time;

(4) designing a residual time estimation formula of each wheeled mobile robot according to the kinematic model in the step (1), and constructing a standard passing error based on information interaction by combining a distribution sequence; the acceleration control along the sight line direction is constructed by utilizing the non-smooth control, so that the standard passing error can be converged to zero in fixed time;

(5) and (4) constructing tangential acceleration and normal acceleration control of the wheeled mobile robot according to the communication network structure, the passing condition of the wheeled mobile robot group and the acceleration control scheme along the sight line direction and the direction perpendicular to the sight line direction designed in the steps (3) and (4).

2. The time-sharing coordination control method for wheeled mobile robot group terminals according to claim 1, characterized in that: assuming that the group is composed of N robots, the kinematic model of the wheeled mobile robot i, i being 1, …, N) in the inertial coordinate system is specifically:

wherein (x)_i,y_i) Position coordinates, theta, representing the center of mass of the robot_iThe heading angle of the robot i, namely the included angle between the speed direction and the x axis, takes the anticlockwise direction as the positive direction, v_iIndicates the velocity of the robot i, ω_iThe course angular rate of robot i;

the coordinates of the target position are taken as (x)^*,y^*) Establishing a kinematic model of the relative position relation between the wheeled mobile robot i and the passing target position:

wherein

Denotes the distance, λ, between the robot and the passing target_i＝atan2(x^*-x,y^*-y) represents the angle of sight, phi_iDenotes the lead angle, a_t,iAnd a_n,iRespectively representing the tangential acceleration and the normal acceleration of the robot i, namely acceleration components of the robot acceleration along the speed direction and vertical to the speed direction;

according to the kinematic model of the relative position relationship, a relationship model of the relative position and the control input can be further established:

wherein u is_r,i＝a_t,icosφ_i-a_n,isinφ_i，u_λ,i＝a_t,isinφ_i+a_n,icosφ_iRespectively representing the acceleration of the robot in the direction of the line of sight and perpendicular to the direction of the line of sight.

3. The time-sharing coordination control method for wheeled mobile robot group terminals according to claim 1, characterized in that: the specific steps of estimating the time of arrival at the passing point and determining the sequence of the robot group passing the target are as follows:

(1) numbering the N robots in the group according to any sequence₁,l₂,…,l_N；

(2) Estimating an estimated time of arrival for each mobile robot in the group according to the initial motion state

Wherein the subscript l ∈ { L }₁,…,l_NDenotes a mobile robot numbered l, t₀Represents an initial time;

(3) the estimated arrival times are arranged in ascending order and the robots are renumbered by 1,2, …, N to meet

And setting the sequence of the robot group passing through the targets as the sequence after renumbering.

4. The time-sharing coordination control method for wheeled mobile robot group terminals according to claim 1, characterized in that: the acceleration control of the wheeled mobile robot i perpendicular to the sight line is constructed by utilizing non-smooth control, so that the speed perpendicular to the sight line can be converged to zero within fixed time, and the control specifically comprises the following steps:

wherein alpha is_λ,i,β_λ,i,p_λ,i,q_λ,i>0 is a constant parameter and satisfies 0<p_λ,i<1<q_λ,iFurthermore function sgn^α(. specifically) is

sgn^α(x)＝|x|^αsign(x)，

Where sign (·) is a sign function.

5. The time-sharing coordination control method for the group terminals of the wheeled mobile robots according to claim 1, characterized in that: the acceleration control of the wheeled mobile robot i along the sight line direction is established by utilizing non-smooth control, so that the standard passing error can be converged to zero in fixed time, and the control is specifically as follows:

(1) establishing network communication connection in a robot group, so that a topological structure of the communication connection contains a directed spanning tree;

(2) calculating a standard pass error ξ using a communication network_i

Where δ represents the time interval between passing target positions of adjacently numbered robots, a_ijElements representing communication topology induced adjacency matrix, i.e. a if robot i can accept the information sent by robot j_ij>0, otherwise a_ij0, in particular, a_ii＝0；

(3) Setting an allowable error

If the wheeled mobile robot i does not pass through the target position, the predicted remaining time of the wheeled mobile robot i may be specifically expressed as:

if the wheeled mobile robot i reaches the target position or is less than epsilon away from the target position, and the passing time is recorded as T_iI.e. the presence of T_iSo that r (T)_i) E is ≦ epsilon, and for

This time game

Counting the time after the robot passes the target position:

t_go,i＝T_i-t；

(4) determining acceleration control of a robot i in a direction of a line of sight

Wherein

Predicted remaining time, α, for wheeled mobile robot i_r,i,β_r,i,p_r,i,q_r,i>0 is a constant parameter and satisfies 0<p_r,i<1<q_r,i。

6. The method for time-sharing coordination control over the terminals of the wheeled mobile robot group according to any one of claims 1, 4 and 5, wherein: the wheeled mobile robot i acceleration and angular acceleration control specifically comprises the following steps:

(1) the wheel type mobile robot i acceleration and angular acceleration control is expressed as follows:

(2) if the wheel-type mobile robot has saturated constraint conditions such as an upper speed limit and an upper acceleration limit, and when the acceleration control designed in the step (5) exceeds the constraint conditions, selecting a corresponding saturated value as control input;

(3) the initial speed direction of the robot in the group forms an obtuse angle or a right angle with the line of sight, i.e. the group is provided with

All robots should be adjusted to the moving direction in advance

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