Computing Movement Geometry

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Computing Movement Geometry

• A step in Sensory-Motor Transformations

Elizabeth Torres David Zipser
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Sensory Input Kinematics
Motor output
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Stuff thats easy in the Geometric Stage

• Specifying movement paths.

• Dealing with excess degrees of freedom.

• Some constraint satisfaction.

• Some error correction.

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Geometric Stage Input -- OutputReaching to
Grasp with a Multi-jointed Arm
What goes on in here?
Represented as changes in joint angles
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Gradient Descent
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Joint Angles
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Gradient Descent for Simulating Hand Translation
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Reconfiguring Joint Angle Space
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Orientation Matching
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Distance function for translation and rotation
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Experiments
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G symmetrical and positive-definite
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Speed Invariance of Movement Path
TARGET
One subject, one movement at each speed
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Six subjects, six movements each
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Co-articulation
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Error Correction
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Correcting error with retinal image feedback
Retina(s)
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Discussion Break
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The gradient of a sum the sum of the gradients
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dq
 

Hidden Units
posture
target position
target orientation
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Preferred Directions Rotate across External Space
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