Chapter 2. Prehension

Activation of
Reaching
Chapter 5 - Movement Before Contact 195
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Orient
Palm
Schema
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Drive Fingers
Guarded
Schema
Actual
Schema
Preshape
Schema
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Figure 5.32 Palm-focused model of setting up opposition space for
prehension. During activation of the Orient Palm Schema,
reaching movements orient the palm and position it close to the
object. In parallel, the Preshape Schema shapes the fingers into a
posture suitable for that palm alignment. When preshaped, posi-
tioned, and oriented, the Drive Fingers Guarded Schema is
activated in order to drive the arm, wrist, and hand in a direction
to make contact with the object. Since it is a guarded movement,
contact with the object will stop the schema, and activate the
Actual Grasp Schema.
Schema configures the fingers into a posture suitable for that palm
alignment. The hand configuration is computed in a palm-centered
coordinate system.
In comparison to the CCP, the Orient Palm Schema in Figure 5.32