specifying inputs for inverse dynamics on Matlab API

[Ilan Eskinazi]

Hi. I'm trying to run inverse dynamics from the Matlab API for a single time frame (e.g. time t1). I want to specify the generalized coordinates and their first and second order time derivatives at time t1, plus the value of external forces acting on time t1, and obtain the inverse dynamics loads for that time t1. My understanding of the problem is that the InverseDynamicsTool forms GCVSplines of the time histories for each coordinate so I cannot explicitly input the generalized velocities and accelerations. Am I right? If so, is there a way to invoke perhaps a lower level function that would allow me to specify all my inputs using Matlab? Or is there another way of doing this? Any sample code would be greatly appreciated.

Thanks,

[Ajay Seth]

Tools are like main programs that allow you to configure them via a setup file. Tools use the API to do general tasks. The heart of solving the inverse dynamics problem is the InverseDynamicsSolver at it solves for the generalized forces given a model state (includes coordinate values, q, and the gen speeds, u) and the generalized accelerations, udot. This is part of the C++ API and we are in the process of making accessible through MATLAB, but we haven't wrapped the InverseDynamicsSolver yet. One possibility to get access to it sooner in MATLAB is to call the solver in a MATLAB mex function written in C++.