Using Robotics System Toolbox on a Closed Loop Robot

Hello,

I'm interested in using the Robotics System Toolbox (RST) to work with a 7-axis robot, where the first 4 joints form a closed loop and the last 3 joints are in an open loop configuration (the first four joints are parallel and the last three are serial). I came across this example: https://fr.mathworks.com/help/robotics/ug/solve-inverse-kinematics-for-closed-loop-linkages.html, which mentions that "Although you cannot directly model closed-loop linkages with the rigidBodyTreeImportInfo object in Robotics System Toolbox™, you can still study the kinematics of closed-loop systems by combining a rigid body tree with constraints that mimic loop-closing joints."

Given this, if I have the URDF or SDF file for such a robot, can I use RST to work with it? If so, how should I implement and analyze the closed-loop kinematics within RST? Additionally, would there be any issues using Simulink with this setup?

Thank you.

Answer 1

[Karsh Tharyani]

Hi @Denizhan AKINCI,

It is the user's choice to decide what becomes a loop closing joint constraint on a tree to represent the inherently closed loop linkage. The example above uses the joint between the base body and the the third link, but you could have a different tree than that and place the loop closing joint accordingly.

generalizedInverseKinematics supports code generation hence they can be used in a MATLAB Function Block.

If you have a reproducible of your model that you would like to share with us in order to aid you better, please don't hesitate to reach out to MathWorks Technical Support.

Hope that helps,

Karsh