I missed this, the notifications from SimTk forums don't always arrive. This reply is very late, but may still be useful for someone. When you use GCVSpline, you generate a spline from the (X,Y) data once, with a specified smoothing setting (the variance parameter). The spline is stored as a series ...

The paper cited by Mohammadreza is very good, but there is one error in the paper that I would like to point out (in case it causes confusion). When a model has moving muscle points, the paper says that equation (1) should be used instead of equation (3). This is, however, not correct. Equation (3) ...

The spatial registration between raw motion capture data and force plate is correct, the center of pressure is exactly were it is expected and not 0.4 meters off. I plotted the horizontal position of COP and a few markers in the lower right leg and foot. Untitled.png The next thing to check would be...

I plotted your data. Untitled.png The joint moment is close to 400 Nm at the peak, which is far too large indeed. The GRF at that time is 1000 N (which is normal), so this means that the center of pressure is about 0.4 meters from the ankle joint. Unless your subject is wearing skis, that is not pos...

Mohammadreza, You probably meant to say "the GCV mode can be implemented ... if I set the errorVariance to a negative value". If you know the variance, you can specify it as a positive value. And the larger that value, the more difference the spline allows between smoothed and raw data. So more smoo...

Just be aware that an accelerometer does not measure acceleration. The marker acceleration is the acceleration expressed in the global reference frame. An accelerometer measures global acceleration but expresses it in a local reference frame (the sensor axes). And there is an effect of gravity. The ...

I have a lot of experience with the GCV spline code (received it in 1985 on a 9-track tape!). The Fortran source code is still available on Netlib at https://www.netlib.org/gcv/gcvspl. After the first page or two, look at the "SUBROUTINE GCVSPL" with good technical information. There is an accompany...

That seems to work! The step velocity value is now consistent with the horizontal speed of the pelvis. Result = 0.667518 CompositeMeasure = 0.667518 Gait = 0 <- 100 * (0.0162636 > 0.05) step_velocity = 1.06426 step_count = 72 Effort = 0.618483 <- 0.1 * 6.18483 effort = 16107.5 distance = 34.943 DofL...

Thomas, Thanks, that is amazing that you were able to fix that so quickly. I will test it immediately if you give me install instructions. I agree that the GaitMeasure should become zero during the optimization so that in the end only the effort is minimized. About the font, yes, it's on Windows. My...

Johannes, The knee is a little different in this model, because the axis of rotation translates relative to the femur. This translation is coupled to the rotation (i.e. a function of knee_angle) and you can find this in translation1 (x) and translation2 (y). Translation y varies from -0.39 to -0.42 ...