Dynamic Walker Model initial walking parameters- model is not walking

[Mainak Chakraborty]

In Dynamic Walker Challenge, I have built the model step-by-step as shown in the tutorial. However, the model is not walking. It is falling behind. I have done forward simulation(0-2s) as shown, still the model is not walking. I have run the Designmainstarter.m script it is not walking. I think I need to change the initial parameters, but there is no template of initial parameters given. Where am I doing wrong?

[Carmichael Ong]

The last paragraph on the example page states that the default values will not produce a walk.

In DesignMainStarter.m, Line 32 appears to be where initial conditions can be changed:

Code: Select all

%% Define the intial coordinate values and speeds for the model. Translations
% coordinates are in meters, rotations are in radians.
pelvisTYValue = 0.8350;
pelvisTYSpeed = 0;
pelvisTXValue = 0;
pelvisTXSpeed  = 0;
rHipValue = deg2rad(30.0);
rHipSpeed = deg2rad(0);
lHipValue = deg2rad(-10);
lHipSpeed = deg2rad(0);
rKneeValue = deg2rad(-30.0);
rKneeSpeed = deg2rad(0);
rKneeValue = deg2rad(-30.0);
rKneeSpeed = deg2rad(0);

[Mainak Chakraborty]

Hi,
This is exactly where I am struck.
Where do I get the initial conditions ? Is there any template files available?
Please suggest.
Thanks

[Carmichael Ong]

I am not aware of template files. My understanding is that you can adjust these values in the .m file, which will set the initial conditions for the next simulation, and the goal of the challenge is to find the values that will lead to a stable walk.

[Thomas Uchida]

There's an example (in Python) on GitHub, under Bindings/Python/examples:
- dynamic_walker_example_optimization.py (https://github.com/opensim-org/opensim- ... ization.py)
- dynamic_walker_example_model.osim (https://github.com/opensim-org/opensim- ... model.osim)
You might look there for differences in model parameters and/or initial conditions. If I recall correctly, it doesn't take that script very long to get the model to walk.