How to make a curve smooth in spline block

Question

dk2507 2017-2-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/327275-how-to-make-a-curve-smooth-in-spline-block

评论： Massimo Zanetti 2017-2-28

Hi, i need to make a cam model in simulink so i use a spline block to model the curve.Here is my code:

clear
clc
s=0:0.005:1;i=0;
 for t1=0:0.005:0.125;
     i=i+1;
    s(i)=(pi*t1-0.25*sin(4*pi*t1))/(pi+4);
 end
for t2=0.130:0.005:0.875;
    i=i+1;
    s(i)=(2+pi*t2-(9/4)*sin((pi+4*pi*t2)/3))/(pi+4);
end
for t3=0.880:0.005:1
    i=i+1;
    s(i)=(4+pi*t3-0.25*sin(4*pi*t3))/(pi+4);
end
T=0:0.005:1;
% plot(T,s);
r=1:1:21;n=0;
for m=1:5:201
    n=n+1;
    r(n)=(232^2+264.2^2-2*232*264.2*cos(deg2rad(20.69+18.5*s(m))))^(1/2);
end
th=60:(110/40):170;
x1=r.*cos(deg2rad(th));
y1=r.*sin(deg2rad(th));
% figure(2);
th2=170:0.5:190;
x2=169.*cos(deg2rad(th2));
y2=169.*sin(deg2rad(th2));
th3=300:(-110/40):190;
x3=r.*cos(deg2rad(th3));
y3=r.*sin(deg2rad(th3));
x3=fliplr(x3);
y3=fliplr(y3);
th4=-60:5:60;
x4=94.55.*cos(deg2rad(th4));
y4=94.55.*sin(deg2rad(th4));
x=[x1,x2,x3,x4];
x=x';
y=[y1,y2,y3,y4];
y=y';
% subplot(5,3,1);
% plot(x,y);
% axis([-150,150,-150,150]);
CAM=[x,y];

But the curve is not smooth,please tell me what is the problem.

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Answer 1

Massimo Zanetti 2017-2-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/327275-how-to-make-a-curve-smooth-in-spline-block#answer_256612

If you want to approximate a set of points by a smooth curve you need a smoothing spline, not just a spline. Moreover, in your case you need the smoothing spline to be a closed curve, therefore with periodic conditions.

I have done a function to do exactly that, check it out:

https://it.mathworks.com/matlabcentral/fileexchange/59463-smoothing-cubic-splines-with-periodic-conditions