1 简介
移动机器人的避障问题是移动机器人控制领域的研究热点。针对给定的移动机器人避障问题 , 探讨了最短路径及最短时间路径的路径规划问题。对于最短路径问题 ,建立 了简化的路径网格模型 ,将其抽象为由节点及边构成的两维图,再使用经典的Dijkstra算法获得可行的最短路径;对于最短时间路径问题 , 通过分析移动机器人弯道运行的速度曲线, 基于几何方法得出了移动时间与过渡圆弧圆心之间严格的数学关系 , 此后借助matlab优化函数获得最佳的移动路径算法可为类似机器人避障问题的解决提供借鉴。
2 部分代码
clc;
clear all;
close all;
cmap = [1 1 1; ...
0 0 0; ...
1 0 0; ...
0 0 1; ...
0 1 0; ...
1 1 0; ...
0.5 0.5 0.5];
colormap(cmap);
%% Define a small map
map_size = 50;
map = false(map_size);
% Add an obstacle
% map (1:20, 6) = true;
% map(20:30, 30:35) = true;
% map(45:50, 20:30) = true;
% map(30:35,1:5) = true;
% calculate the potential field for robots
start_coords = [1, 1];
dest_coords = [50, 50];
[distanceFromStart_ ] = DijkstraGrid (map, dest_coords, start_coords);
distanceFromStart_(dest_coords(1), dest_coords(2)) = 0;
disp(distanceFromStart_ );
%% path planning for swarm robots using PSO
%Problem Defination
CostFunction = distanceFromStart_ ; %CostFunction
nVar = 2; %Number of Variables
VarSize = [1, nVar]; %Matrix Size of Decision Variables
%Parameters of PSO
nPop = 20; %Population Size(Robot Number)
w = 0; %w = 1; %Intertia Coefficient
wdamp = 0.9; %Damping Ratio of Inertia Coefficiennt
c1 = 0; %c1 = 1.5 %Personal Acceleration Coefficiennt
c2 = 2; %Social Acceleration Coefficient
%Initialization
%The Particle Template
empty_particle.Position = [];
empty_particle.NextPosition = [];
empty_particle.Velocity = [];
empty_particle.Cost = [];
empty_particle.Goal = [];
empty_particle.Best.Position = [];
empty_particle.Best.Cost = [];
empty_particle.Best.Index = [];
%Create Population Array
particle = repmat(empty_particle, nPop, 1);
%Initialize Global Best
GlobalBest.Cost = inf;
%Initialize Population Members
%%Initialize Position and Goal
particle(1).Position = [1, 1]; particle(1).Goal = [50, 50];
particle(2).Position = [1, 2]; particle(2).Goal = [50, 49];
particle(3).Position = [1, 3]; particle(3).Goal = [50, 48];
particle(4).Position = [1, 4]; particle(4).Goal = [50, 47];
particle(5).Position = [2, 1]; particle(5).Goal = [50, 46];
particle(6).Position = [2, 2]; particle(6).Goal = [49, 50];
particle(7).Position = [2, 3]; particle(7).Goal = [49, 49];
particle(8).Position = [2, 4]; particle(8).Goal = [49, 48];
particle(9).Position = [3, 1]; particle(9).Goal = [49, 47];
particle(10).Position = [3, 2]; particle(10).Goal = [49, 46];
particle(11).Position = [3, 3]; particle(11).Goal = [48, 50];
particle(12).Position = [3, 4]; particle(12).Goal = [48, 49];
particle(13).Position = [4, 1]; particle(13).Goal = [48, 48];
particle(14).Position = [4, 2]; particle(14).Goal = [48, 47];
particle(15).Position = [4, 3]; particle(15).Goal = [48, 46];
particle(16).Position = [4, 4]; particle(16).Goal = [47, 50];
particle(17).Position = [5, 1]; particle(17).Goal = [47, 49];
particle(18).Position = [5, 2]; particle(18).Goal = [47, 48];
particle(19).Position = [5, 3]; particle(19).Goal = [47, 47];
particle(20).Position = [5, 4]; particle(20).Goal = [47, 46];
%initial the map to show
map_plot = zeros(map_size);
map_plot(~map) = 1; % Mark free cells
map_plot(map) = 2; % Mark obstacle cells
for i = 1:nPop
%Initialize Velocity
particle(i).Velocity = zeros(VarSize);
%Evaluation
particle(i).Cost = CostFunction(particle(i).Position(1), particle(i).Position(2));
%Update the Personal Best
particle(i).Best.Position = particle(i).Position;
particle(i).Best.Cost = particle(i).Cost;
particle(i).Best.Index = i;
map_plot(particle(i).Position(1), particle(i).Position(2)) = 4;
%Update Global Best
if (particle(i).Best.Cost < GlobalBest.Cost )
GlobalBest = particle(i).Best;
end
end
map_plot(GlobalBest.Position(1), GlobalBest.Position(2)) = 3;
ShowImage(map_plot);
%% Main Loop of PSO
while (GlobalBest.Position(1) ~= dest_coords(1) || GlobalBest.Position(2) ~= dest_coords(2) )
for i = 1:nPop
%Judge Leader
if (i == GlobalBest.Index)
%Get the Surrouding Positions
neighbours = GetSurroundingPositions(particle(i).Position);
p_x = particle(i).Position(1);
p_y = particle(i).Position(2);
MinCost = inf;
end
%check if the NextPosition will colllision with other particles or not
for i= 1:nPop
if(map_plot(particle(i).NextPosition(1), particle(i).NextPosition(2)) ~=1)
particle(i).NextPosition = particle(i).Position;
end
%Update the map_plot
map_plot(particle(i).Position(1), particle(i).Position(2)) = 1;
particle(i).Position = particle(i).NextPosition;
map_plot(particle(i).Position(1), particle(i).Position(2)) = 4;
end
%change the goal according to the position of the particle randomly
if (mod(randperm(100,1), 10) > 4)
goal_assigned = GoalAssignment(reshape([particle(1:nPop).Position], 2, nPop)', reshape([particle(1:nPop).Goal], 2, nPop)');
for i=1:nPop
particle(i).Goal(:) = goal_assigned(i, :);
end
end
%Display
ShowImage(map_plot);
%check the task is finished or not
end
3 仿真结果
4 参考文献
[1]邹益民, 高阳, 高碧悦. 一种基于Dijkstra算法的机器人避障问题路径规划[J]. 数学的实践与认识, 2013, 043(010):111-118.
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