Does force/torque get transfered throughtout an assembly consisting of solid blocks assembled with rigid transforms and connected with joints and gear constraints?

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Joben Kennard Arroyo 2020-8-5

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评论： J Chen 2020-8-10

Hi. Im making a swing door assembly. I import the components as cad file from autodesk inventor and assemble them using rigid transforms in simulink/simscape environment. I add joints and gear constraints to necessary components to ensure that they move correctly relative with each other. I input a force to the door knob, located at a specific distance from the axis of rotation of the door (hinge). Does the torque produced by this force get transfered to the gears and shafts and all throughtout the assembly? What should i do to make it so? I am able to simulate the assembly if a set the torque actuation of all the revolute joints to "none". The block diagram of my assembly is attached below. I will greatly appreciate any help. Thanks!

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Answer 1

J Chen 2020-8-6

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Simscape models are just link physical system. You apply force/torque at a particular point. The system with reponse to the force/torque based on the constraints, just like the physical system. The force/torque get transmitted through each joints. The actuation force/torque at a joint is the EXTERNALLY applied torque, not the INTERNAL force/torque.

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Joben Kennard Arroyo 2020-8-10

Thanks for responding! I wasn't notified by the reply so im sorry with this late reply.

I made some adjustments with my model but the problem is still the same. I removed the input force at the knob. I input motion to the revolute joint between the door and hinge. I set the torque actuation of all the revolute joints to automatically computed. But when i simulate i get this error;

"In the dynamically coupled component containing Revolute Joint 'SDL/SwingMotion', there are more joint primitive degrees of freedom with automatically computed force or torque (4) than with motion from inputs (0). In general, the equations of motion do not have a unique solution. Solve this problem by increasing the number of joint primitives with motion from inputs or reducing the number of joint primitives with automatically computed force or torque. Resolve this issue in order to simulate the model."

I intend to do something like this model: sm_welding_robot ,wherein motion profile is inputed so that the torque can be computed. What am i doing wrong? I suspect the torque from the motion input weren't transfered in the system, but i dont know why this is not the case in my model. Ill very appreciate your help. Thanks!

J Chen 2020-8-10

I'm not sure this is the problem: when you specify revolute joint motion in the Actuation, the Toque should be "Automatically Compouted", the Motion should be "Provided by Input". The Simulink to PS Converter used to input the motion should have a filter specified in the Input Handling tab.

Another possibility is that Simscape might not be able to assemble your model due to phsical conflict. I would suggest delete the motion inputs and find out the simulation will run or not.

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