Question

我真的坚持这个代码。我试图模拟物理问题来形象化问题。它有2个栓钉和两个弹簧连接到一个质量，在x方向上有50N的横风。我不太确定如何在x和y中结合限制来获得结果。请任何帮助

%position of peg1
pegX1 = 3;
pegY1 = 10;

%position of peg2
pegX2 = 8;
pegY2 = 10;

%position of mass
xPos = 5;
yPos = 6;

%velocity of mass
xVel = 0;
yVel = 0;

%mass of mass
m = 2;

%constant of springs
k1 = 20;
k2 = 25;

%equilibrium distance of spring
eq1 = 2;
eq2 = 1.5;

%constant of gravity
g = 5;

%define time domain
dt = 0.1;
t = 0:dt:100;

%record all previous positions for plot
positions = zeros(2,length(t));


for i = 1:length(t)
    %find angle between peg1 and mass
    theta1 = direction(xPos,yPos,pegX1,pegY1);

    %find angle between peg2 and mass
    theta2 = direction(xPos,yPos,pegX2,pegY2);

    %calc X resultant force
    FresX = -1*(eq1-dist(xPos,yPos,pegX1,pegY1,pegX2,pegY2))*k1*k2*cos(theta1+theta2);

    %calc Y resultant force
    FresY = -1*(eq1-dist(xPos,yPos,pegX1,pegY1,pegX2,pegY2))*k1*k2*sin(theta1+theta2) - m*g;

    %calculate acceleration due to force
    aX = FresX/m;
    aY = FresY/m;

    %change velocity based on acceleration
    xVel = xVel + aX*dt;
    yVel = yVel + aY*dt;

    %change position based on velocity
    xPos = xPos + xVel*dt;
    yPos = yPos + yVel*dt;

    %record position for plot
    positions(1,i) = xPos;
    positions(2,i) = yPos;

    %plot position
    p1 = plot(positions(1,1:i),positions(2,1:i),'r');
    axis([0 4.5 0 4.5]);
    grid on
    pause(0.1)
end

Answer 1

我不明白你的意思是限制。

我改变了合力的定义方式。

function m = test
%position of peg1
pegX1 = 3;
pegY1 = 10;

%position of peg2
pegX2 = 8;
pegY2 = 10;

%position of mass
xPos = 5;
yPos = 6;

%velocity of mass
xVel = 0;
yVel = 0;

%mass of mass
m = 2;

%constant of springs
k1 = 20;
k2 = 25;

%equilibrium distance of spring
eq1 = 2;
eq2 = 1.5;

FWind = 50;

%constant of gravity
g = 5;

%define time domain
dt = 0.05;
t = 0:dt:100;

%record all previous positions for plot
positions = zeros(2,length(t));

figure(1)
i = 1;
%title([num2str(0), ' s'])
plot(xPos, yPos, 'bo', pegX1, pegY1, 'go', pegX2, pegY2, 'ro');
drawnow
d = max([distance(xPos,yPos,pegX1,pegY1), distance(xPos,yPos,pegX2,pegY2)]);
axis([min([pegX1, pegX2])-d, max([pegX1, pegX2])+d, min([pegY1, pegY2])-d, max([pegY1, pegY2])+d])
ax = gca;
ax.NextPlot = 'replaceChildren';

positions(1,i) = xPos;
positions(2,i) = yPos;

Frame(i) = getframe;

    for i = 2:length(t)
        %find angle between peg1 and mass
        theta1 = direction(xPos,yPos,pegX1,pegY1);

        %find angle between peg2 and mass
        theta2 = direction(xPos,yPos,pegX2,pegY2);

        %calc X resultant force
    %    FresX = -1*(eq1-dist(xPos,yPos,pegX1,pegY1,pegX2,pegY2))*k1*k2*cos(theta1+theta2);

        FX = k1 * (distance(xPos,yPos,pegX1,pegY1) - eq1) * cos(theta1) + ...
                k2 * (distance(xPos,yPos,pegX2,pegY2) - eq2) * cos(theta2) + ...
                FWind;

        %calc Y resultant force
    %    FresY = -1*(eq1-dist(xPos,yPos,pegX1,pegY1,pegX2,pegY2))*k1*k2*sin(theta1+theta2) - m*g;

        FY = k1 * (distance(xPos,yPos,pegX1,pegY1) - eq1) * sin(theta1) + ...
                 k2 * (distance(xPos,yPos,pegX2,pegY2) - eq2) * sin(theta2) ...
                 -m * g;

        %calculate acceleration due to force
        aX = FX/m;
        aY = FY/m;

        %change velocity based on acceleration
        xVel = xVel + aX*dt;
        yVel = yVel + aY*dt;

        %change position based on velocity
        xPos = xPos + xVel*dt;
        yPos = yPos + yVel*dt;

        %record position for plot
        positions(1,i) = xPos;
        positions(2,i) = yPos;

%        title([num2str(t(i)), ' s'])
        plot(xPos, yPos, 'bo', pegX1, pegY1, 'go', pegX2, pegY2, 'ro');
        drawnow
        Frame(i) = getframe;
    end

    %plot position
    figure(2)
    p1 = plot(positions(1,:),positions(2,:),'r');
    axis('tight');
    grid on

    figure(1)
    movie(Frame);

end

function theta = direction(x1,y1,x2,y2)
    theta = atan2(y2 - y1, x2 - x1);    
end

function d = distance(x1, y1, x2, y2)
    x = x2 - x1;
    y = y2 - y1;

    d = sqrt(x^2 + y^2);
end

MatLab中的物理模拟

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