Hit-and-Run sampling is an effective method for identifying task-irrelevant variation in generating fixed output forces at the fingertip. The polytope representing possible motor commands changes over time and could illustrate how motor commands are constrained within a probabilistic space. Motor control and learning exist within this probabilistic space.

1. Hit-and-Run sampling of
neuromechanical
polytopes
▷ Bernd Gärtner
▷ Komei Fukuda
▷ May Szedlák
▷ Francisco Valero-Cuevas
▷ Brian Cohn

2. Claims
A. Hit-and-Run is effective for identifying task-
irrelevant variation in generating a fixed output
force at a fingertip.
B. The change in a Polytope over time could
illustrate how motor commands are constrained.
C. Motor control and learning exists within a
probabilistic space

3. 1.
Introduction to Tendon-
Driven Systems

4. Why do we have so many
muscles?

6. Would you be willing to remove a muscle to
improve efficiency?

7. The muscle redundancy
problem
We often have many more muscles than
kinematic degrees of freedom.
How are the muscles controlled?

8. 2.
Biological modeling

15. 3.
Simple example

21. 0N
20N
40N

25. Thanks!
Open questions:
▷ How should we deal with spatiotemporal
constraints?
▷ What other ways could we use to visualize these
spaces?
▷ Which input elements (when permuted) would you
expect to have the highest impact on the results?
briancohn@usc.edu