Hi all,

I am working on a motion analysis of bone movement. I have given a bone 3 motors (on 3 planes) and they move perfectly. I would like to add a torque as an intervention but it could not be calculated simultaneously with the 3 motors. The torque is running in an opposite direction with one of the motors. So I suppressed the 3 motors and try calculated the motor by itself. It works! So I wonder if anyone knows how to tackle this problem.

Thanks!!

Please excuse me if I'm misinterpreting your question, but the symptoms remind me of problems I have had in the past. When I first started using SolidWorks, one of the conceptual problems I had was that the word Motor to me meant a motivator that would supply a torque, like an electric motor.

In Motion, Motor is a mathematical construct which forces the parts to a certain position or velocity regardless of any other forces involved.

I suspect that is what you are seeing. If you are dictating the rotational position of a joint in three planes and then applying another torque on top of that, the torque will have no effect.

To get around this in the past, I have created torques using expressions which simulate the behavior of a motor. It is a bit complicated but does simulate real systems better than the simple 'motor'.

1. Measure the velocity of the component as a Plot. That velocity will now be accessible as an equation.

2. Create a torque on the part which simulates what you wish in which the torque is the 'stall torque' at zero speed and is inversely proportional to the speed.

This might be far more trouble than you are hoping for, but if it seems appealing let me know and I can provide some further guidance. If you can post your model it is more likely to get help.