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Q-Learning

二维避障轨迹规划

目前我写的代码不够成熟，就不贴了。Agent的reward机制如下：走出图像reward为一个较大负数，撞上障碍也为一个较大负数，若不是前两者，则reward为当前点位与目标点位距离的反比函数（越近奖赏越大）。
state状态的划分是根据像素区域来的，等同于把图像分割成了若干像素块，这样可以减小state的数量，否则训练困难。Action根据移动方向的角度来分，比如10°划分的话一个state就有36个actions，这样Q表就是$states\times actions$尺寸的矩阵。

结果

结果基本全图收敛。

代码

注：这只是个学习程序，实用价值不高。

clc;clf;clear;
%% 加载图片二值化(方形图片)
map=imbinarize(imread('test2.bmp')); % input map read from a bmp file. for new maps write the file name here
map = map(:,:,1);        %三通道取前两个通道
%% 参数初始化
statePixSize = 100;   %像素方格视为一个state
stateNumRow = size(map,1)/statePixSize; 
stateNum = stateNumRow^2;
source = [192,263]; %初始点
goal = [757,779]; %目标点
iter1 = 100;   %学习迭代次数 
iter2 = 3000;   %每次迭代内循环次数
state0 = calculateState(source(1),source(2),stateNumRow,statePixSize); %起始点的状态
stateGoal = calculateState(goal(1),goal(2),stateNumRow,statePixSize); %goal的状态
angle = 10;  %一个action度数
actionNum = 360/angle;
Q = zeros(stateNum,actionNum);
e = 0.3;    %解决探索和开发
gamma = 0.9; alpha = 0.5;
stepSize = 100;
threshold = 200;


%% 学习循环
for i = 1:iter1
%     randXY = randperm(size(map,1),2);
%     x = randXY(1); y = randXY(2);
%     state = calculateState(x,y,stateNumRow,statePixSize);
    state = state0;
    x = source(1); y = source(2);
    for j = 1:iter2
        % 当前state下做出action决策
        randNum = rand;
        if(rand>e)
            [~,action] = max(Q(state,:));
        else
            action = randperm(actionNum,1);
        end
        % 判断在该决策下到达的下一个state
        xNext = x + stepSize * sin((action-1)*angle/180*pi);
        yNext = y - stepSize * cos((action-1)*angle/180*pi);
        if(xNext<=0 || xNext >= size(map,1) || yNext<=0 || yNext >=size(map,2))
            Q(state,action) = -10000;
            continue;
        end
        newState = calculateState(xNext,yNext,stateNumRow,statePixSize);
        % 判断碰撞与否以及是否到达goal 并observe reward
        if checkPath([x,y],[xNext,yNext],map)
            reward = 2000/(1+distanceCost([xNext,yNext],goal));
            if newState == stateGoal
                reward = 1000;
            end
            Q(state,action) = Q(state,action) + alpha * (reward + gamma * max(Q(newState,:)) - Q(state,action));
        else
            reward = -5000;
            Q(state,action) = Q(state,action) + alpha * (reward + gamma * max(Q(newState,:)) - Q(state,action));
        end        
        state = newState;
        x = xNext; y = yNext;
    end
    if ~mod(i,10)
        str = sprintf('Q-Learning学习进度：%d%%',vpa(i/iter1*100,2));
        disp(str);
    end
end

%% 验证
imshow(map);
rectangle('position',[1 1 size(map)-1],'edgecolor','k'); hold on;
scatter(goal(1),goal(2),100,"filled","b");
testPoint = [200 100;200 200;200 300;200 400;200 500;200 600;200 700;200 800;200 900];
for i = 1 : size(testPoint,1)
    scatter(testPoint(i,1),testPoint(i,2),100,"filled","g");
    
    x = testPoint(i,1); y = testPoint(i,2);
    state = calculateState(x,y,stateNumRow,statePixSize);
    path = [x,y];
    try
        while distanceCost([x,y],goal) > threshold
            [~,action] = max(Q(state,:));
            xNext = x + stepSize * sin((action-1)*10/180*pi);
            yNext = y - stepSize * cos((action-1)*10/180*pi);
            newState = calculateState(xNext,yNext,stateNumRow,statePixSize);
            if ~checkPath([x,y],[xNext,yNext],map)
                break;
            end
            state = newState;
            x = xNext; y = yNext;
            path = [path;x,y];
        end
        plot(path(:,1),path(:,2),[path(end,1),goal(1)],[path(end,2),goal(2)],'LineWidth',2);
    catch
        disp("error!")
    end
end


% for i = 1:50
%     [~,action] = max(Q(state,:));
%     xNext = x + stepSize * sin((action-1)*10/180*pi);
%     yNext = y - stepSize * cos((action-1)*10/180*pi);
%     newState = calculateState(xNext,yNext,stateNumRow,statePixSize);
%     state = newState;
%     x = xNext; y = yNext;
%     path = [path;x,y];
% end
% plot(path(:,1),path(:,2));

calculateState.m

function state = calculateState(x,y,stateNumRow,statePixSize)
    rowNum = ceil(y/statePixSize);
    colNum = ceil(x/statePixSize);
    state = (rowNum-1) * stateNumRow + colNum;
end

checkPath.m

%% checkPath.m	
function feasible=checkPath(n,newPos,map)
feasible=true;
dir=atan2(newPos(2)-n(2),newPos(1)-n(1));
for r=0:0.5:sqrt(sum((n-newPos).^2))
    posCheck=n+r.*[cos(dir) sin(dir)];
    if ~(feasiblePoint(ceil(posCheck),map) && feasiblePoint(floor(posCheck),map) && ... 
            feasiblePoint([ceil(posCheck(1)) floor(posCheck(2))],map) && feasiblePoint([floor(posCheck(1)) ceil(posCheck(2))],map))
        feasible=false;break;
    end
    if ~feasiblePoint(floor(newPos),map), feasible=false; end
end
end

distanceCost.m

function h=distanceCost(a,b)         %% distanceCost.m
	h = sqrt(sum((a-b).^2, 2));
end

feasiblePoint.m

%% feasiblePoint.m
function feasible=feasiblePoint(point,map)
feasible=true;
% check if collission-free spot and inside maps
if ~(point(1)>=1 && point(1)<=size(map,1) && point(2)>=1 && point(2)<=size(map,2) && map(point(1),point(2))==1)
    feasible=false;
end
end

test2.bmp

最后

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