coordinate.setSpeedValue(state, value) takes the state object and the value of the speed you want to set in the state. To ensure that the actuator then respects the new speed, you want to call model.computeStateVariableDerivatives(state); to make sure all internal dynamics are realized. Then you can...

An inverse kinematics analysis is a purely kinematic analysis. There is no evaluation of any forces (no system dynamics). Specifically, it is the solution for the generalized (or internal) coordinates (joint angles, etc...) that match measurements of spatial (or absolute) coordinate measurements suc...

calcPower returns a double not an Array<double>

You can find the methods on ModelComponents in Doxygen e.g. https://simtk.org/api_docs/opensim/api_docs/classOpenSim_1_1Coordinate.html . Coordinate has methods to set the default coordinate value and its speed. These should be accessible via scripting in Matlab and you can see the methods using tab...

Your point 1 is irrelevant to PinJoint. The functions in CustomJoint are inside a SpatialTransform which allows you to couple spatial (6dof) kinematics to between 1 and 6 internal coordinates. A PinJoint is not arbitrary and is defined to rotate about the respective Z axis of the parent and child fr...

1. Good question. The default coordinate value and its speed are overruled by the prescribed motion when the constraint is satisfied (when the model is assembled e.g. at initSystem()). 2. What is the purpose of the CoordinateActuator if the motion is prescribed? The prescribed motion will compensate...

It would be easier to prescribe the motion of the coordinate. Inside the Coordinate block that you want to prescribe, add: <!--If specified, the coordinate can be prescribed by a function of time. It can be any OpenSim Function with valid second order derivatives.--> <prescribed_function> <LinearFun...

actControls.set(FD, val); %FD= muscle force

looks incorrect.

actControls should be a Vector of length 1, so you should be setting the value not the index to the force value:

We cannot stop you from calling s.getY() etc.. on the State. I guess you can always figure out the order yourself. For others reading this post I strongly advise against doing this since their is absolutely no guarantee that the state layout will remain the same between model versions or releases of...

Perhaps what you are looking for is in the Doxygen that documents the code base. Locally you can find it here: <OpenSim32_Install_DIR>\sdk\doc\OpenSimAPI.html Online: https://simtk.org/api_docs/opensim/api_docs/ Furthermore, a Controller is an OpenSim component whose job it is to generate controls f...