how to fix ode45 parameters?

Question

Valeria Leto 2021-3-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/764816-how-to-fix-ode45-parameters

回答： Cam Salzberger 2021-7-7

Error using derivative
Expected state to be finite.
Error in jointSpaceMotionModel/derivative (line 251)
            validateattributes(state, {'double'}, {'nonempty', 'vector', 'numel', 2*obj.NumJoints,
            'finite', 'real'}, 'derivative', 'state');
Error in file_verifica_controllori>@(t,y)derivative(computedTorqueMotion,y,qDesComputedTorque) (line
31)
[tComputedTorque,yComputedTorque] =
ode45(@(t,y)derivative(computedTorqueMotion,y,qDesComputedTorque),tSpan,initialState);
Error in ode45 (line 299)
    f2 = odeFcn_main(t2, y2);
Error in file_verifica_controllori (line 31)
[tComputedTorque,yComputedTorque] =
ode45(@(t,y)derivative(computedTorqueMotion,y,qDesComputedTorque),tSpan,initialState);

Hi! what's the problem with ode45? I tried to reduce the step size but didn't work.

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Answer 1

Cam Salzberger 2021-7-7

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https://ww2.mathworks.cn/matlabcentral/answers/764816-how-to-fix-ode45-parameters#answer_741723

The value of "y" (the "state" input to "derivative") is going infinite or NaN at some point. I'd suggest creating a helper function that calls derivative, and use the helper function as the ode45 function. Then you can either add some printout statements or insert a breakpoint so you can see when the state is going infinite and possibly why.

-Cam