problem with joint auctator input signal in simmechanics

Hi,I'm trying to give s constant input signal to a joint actuator to rotate a revolute joint. I use a constant value block with a 1-D array like [0,20,0] for position,velocity,acceleration but it doesn't move! when I change the position input(first number) the starting condition of my body changes but it still doesn't move. I'm new to simulink so I will be thankful if you can give me a descriptive answer.

Answer 1

[Andreas Goser]

This is one of the questions that is difficult to process in MATLAB Answers as too much guessing is involved when not having the model. Maybe you can try an existing and working demo model and identify what is different?

Answer 2

[Arnaud Miege]

I assume you are using motion actuation. If that's the case, you want to make sure that the position, velocity and acceleration are consistent, i.e. that v = dx/dt and a = dv/dt. That's not the case with the values you're using. Good practice is to start with acceleration and then integrate to get velocity and integrate again to get position. For more details, see About actuators in the the SimMechanics documentation.

HTH,

Arnaud

[Arnaud Miege]

You may also want to have a look at the following on the File Exchange:

http://www.mathworks.co.uk/matlabcentral/fileexchange/27589-motion-driver-for-simmechanics