How can I use the "Lead Screw with Friction" Simscape model together with the "Stepper Motor with Control" model?

Hello, there!

I am currently working on a 3-axis scanner, this is, three lead screws (X, Y, Z) that should move. The X one is independent, while the Z is coupled and moves together with the X, and lastly the Y lead screw is coupled into the Z plate.

To simulate the dynamics, I have created a Simscape model. I have coupled 3 lead screws (doing the proper translation and rotations to get the desired 'shape') and then, to try, I tried to make the stepper motor an input for the lead screw, as can be seen in the image, thanks to a Rotational Multibody Interface.

It works pretty well if I only do it with one axis, but the moment I put another lead screw on top of the lead screw that moves thanks to the stepper motor, it starts oscillating and does not move as expected. Can someone help me? Thank you!

Answer 1

[Vijeta]

Hi,

It sounds like you are experiencing coupling effects between the lead screws when you try to move them together. There are a few steps you can take to try to address this issue:

1. Check that your lead screw models are physically accurate and well-behaved. For example, there should be no singularities or unrealistic assumptions in the kinematics or dynamics models.
2. Make sure that your lead screw models are properly connected and constrained. You may need to use additional constraints or degrees of freedom to ensure that the lead screws move as expected and do not introduce any unwanted coupling effects.
3. Check the properties of your stepper motor model and verify that they are appropriate for your application. For example, the torque-speed curve of the motor should match the requirements of your lead screw system, and the motor damping and inertia parameters should be representative of the actual motor you are using.
4. Experiment with different control strategies for the stepper motor. You may need to adjust the controller gain, frequency response, or other parameters to achieve stable motion control with multiple lead screws.
5. Consider adding feedback sensors to your system, such as encoders or position sensors, to enable closed-loop control and improve the stability and accuracy of the lead screw motion.