SIMSCAPE MULTIBODY: Apply Forces / Sense velocity of GLOBAL Center of Mass

Good day everybody,

Basically i need to sense the velocity of the Center of Gravity (CoG) of the system and possibly apply forces directly there. I tried to attach a 6-DoF Joint to the CoG but I haven't yet managed to do it. I cannot understand how to assign the motion of the CoG (sensed with INERTIA SENSOR) to the 6-DoF Joint block. I tried 'de-muxing' the signal but algebraic loops form and there seems to be no solution (Mux/Demux for physical signals - MATLAB Answers - MATLAB Central (mathworks.com)).

I also tried to follow what discussed in Placing a Joint on a Moving Center of Mass in Simscape Multibody - MATLAB Answers - MATLAB Central (mathworks.com) but as I described above it doen't work for me.

Thank you for your help!

Answer 1

[J Chen]

First add a new frame to the Center of Gravity (CoG). Connect a 6 DoF Joint between the new frame to the World Frame.

Specify the motion of the CoG by specifying X Prismatic Primitive - Actuation - Force - Automatically Computed and X Prismatic Primitive - Actuation - Motion - Provided by Input. Do the same for Y and Z. Feed the desired values to the motion inputs through Simulink-PS Converter blocks and specify Filtering in the Input Handling tab (refer to this example https://www.mathworks.com/help/sm/ug/prescribe-joint-motion-in-four-bar-model.html).