Restricting motion for a sinusoidal force input in simscape

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AHMED OUBAED 2020-7-13

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https://ww2.mathworks.cn/matlabcentral/answers/564383-restricting-motion-for-a-sinusoidal-force-input-in-simscape

评论： Steve Miller 2022-12-20

I am inputting a sinsoidal input and pushing it through all kinematics and jacobian transposes to derive the desired force needed,

When i directly input the sinusoidal input to a prismatic joint (after choosing Force as an input to the joint) the model does't follow the trajectory but goes up OR down infinetly. How can i make prismatic joints follow a sinusoidal input by choosing force an an input to that joint,

(from figure, the end effector goes up infinietly)

Worth mentioning is that i am not taking any measurements (readings) from the joint i am calculating the desired force through a different kinematics and dynamics subsystem and then the calculated force is fed to the prismatic joints,

How can this be solved?

Thank you so much

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Answer 1

Steve Miller 2022-12-20

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Hi @AHMED OUBAED

Without seeing your exact model, it is hard to say exactly what the problem is.

Here are my best guesses:

You need to start your force sine wave with a phase angle of 90 degrees (or pi/2). If you apply a sine wave with a phase of 0 degrees, you will accelerate in one direction during the positive portion of the sine wave, and then decelerate back to 0 speed during the negative portion of the sine wave, but never have negative velocity. Your mechanism will move in steps in the same direction infinitely.
Your force is not strong enough to overcome gravity.

--Steve