Chapter 2. Prehension

Shape
obiect
Chapter 2 - Prehension 43
Task
Apply forces
Impart motion
characteristics Gather sensory information
Size
Prehension in I Prehension in
Taxonomv terms Qppos ition mace te rma
Power grasp Opposition state variables
Addwted thumb number of oppositions
Cylindrical grasp type of oppositions
Spherical grasp mapping
Precision grasp W state variables
Precision handling
Tripod Virtual Finger state variables
DyMmic Tripod length
Lateral pinch orientation
Addudion grip width
Gravity-dependent grasp grasping surface patch orientation
Hook available force
Platform available sensory information
Antenna
Figure 2.10. Mapping between Object, Task, and Prehensile behav-
iors. Specific object properties affect the chosen posture. Task
requirements of applying forces, imparting motions, and gathering
sensory information can be matched by the functional capabilities
of the hand. Prehensile postures can be described either in opposi-
tion space terms or according to the classifications.
In pad opposition, the hand can exert small forces, impart fine
motions, and gather precise sensory information to match the accuracy
and manipulation requirements of the task. Landsmeer’s extension to
Napier’s classification made clear this dynamic component of preci-