How to rotate a solid with revolute joint

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Leeann Newton 2020-9-15

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https://ww2.mathworks.cn/matlabcentral/answers/594343-how-to-rotate-a-solid-with-revolute-joint

评论： Vasco Lenzi 2020-9-18

I've created this block and link. I'm trying to make the link rotate on the surface of the block. I've read in the documentation that the z axis should point in the direction that I want it to rotate. However, I cannot seem to get the joint working.

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Answer 1

Ameer Hamza 2020-9-16

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https://ww2.mathworks.cn/matlabcentral/answers/594343-how-to-rotate-a-solid-with-revolute-joint#answer_495283

sim_model_2019b.mdl

See the attached file for an example.

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Leeann Newton 2020-9-16

sampleM1L1.slx

I have this, but it only works if the gravity is in the Y direction and I'm trying to recreate it without changing the direction of the gravity

Vasco Lenzi 2020-9-18

sampleM1L1_19b.slx

The joint per se will not rotate if there is no external force acting on it. When you change the gravity to y, you see movement because there is a force. If you have gravity on the z and the system setup as in your pictures, of course it would not move because no force is acting on the joint!

You need to add a torque to the joint to make it move. I'm attaching an example where I give torque for one second and then stop for the other 9 seconds of the simulation. The rod starts rotating and continue to rotate because there are no internal mechanics (damping, friction) acting on the rotation.

Additionally you may not see the movement because the rod is all red with no distinctive mark - I've added a black line as a marker

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