3. From the example "ExampleMotorWithSpeedControl": MyTorqueLimitedMotor (const MobilizedBody& mobod, MobilizerUIndex whichU, Real gain, Real torqueLimit) What is the use of MobilizeUIndex. According to my understanding U stand for generalized speed, which contains 6 elements ( 3 angular and 3 linea...

In DzhanibekovEffect, you were surprised that changing the angular velocity from (10, 0, 1e-10) to (10, 10, 1e-10) caused translation to occur. That's because the angular velocity value you chose gave the system center of mass a non-zero translational velocity. You can see that by adding the followi...

These are great questions, thanks Amit. I'll answer one per post: I want to provide Initial angular velocity to the whole body , not one body. is function "setUToFitAngularVelocity" (https://simbody.github.io/3.5.0/classSi ... de27544411), but this function only provide the angular velocity between ...

I think you wanted: so that you are working with the actual MobilizedBody in your system rather than a copy.

I'm not familiar with OpenSim's IK interface so this is just Thanksgiving speculation in case no one else is available: - assuming there is a way to loosen the tolerance, you may find you can solve the problem using joints and constraints with a little more slop allowed - you may have a problem with...

This diagram may help (scroll down to "Mobilizer Terminology and Notation") -- notice that a mobilizer is a relationship between two frames. One (F) is on the parent (inboard) body and the other (M) is on the child (outboard) body. A Pin mobilizer aligns the Z axes of those two frames. Each frame c...

You are correct that kinematics doesn't consider forces so the force elements don't affect IK. IK always respects joints and should satisfy constraints also. "To a tolerance" means that (unlike joints) constraints won't be satisfied perfectly (that is, to machine precision). Instead there will be so...

Tom beat me to answering and gave a better answer than I would have! (Hi, Tom) To elaborate a little -- in your example of a Weld joint vs. Weld constraint: Say we weld body A to body B. With a weld joint, A and B essentially become the same body, with B attached exactly as specified by the joint. T...

Hi, Harshal. An important thing to know is that Simbody expects inertias to be provided taken about the body origin, NOT the body mass center. I suspect your specification of the motor inertia was intended to be about the COM (0,0,.4) but Simbody interpreted it about (0,0,0) which, when shifted to (...

Of course there is a limit to how big a system can run in real time, but I don't think you're close to it yet. Take a look at "ChainExample". That's an interactive 3d example with 100 bodies connected by ball joints so 300 dofs. Depending how stiff your springs are, you might find an explicit integr...