Finger and Grasp Impedance We have worked to determine how humans modulate the mechanical impedance of their hands in response to task requirements. The results help explain sensing and motor control strategies in dextrous manipulation. Our approach involves experimental measurement of force-motion relationships of the hand and fingers during task execution. These studies have measured the impedance of the index finger in extension and abduction, and the impedance of the precision pinch grasp during lifting. |
Drumming These measurements form the basis for the biomechanical analysis of drumming. This task is of particular interest because skilled drummers can play drum rolls at frequencies well in excess of the usual human motor control bandwidth. They do this by allowing the drumstick to bounce passively against the drum head at least twice for each hand stroke. We have obtained experimental evidence with an instrumented drumstick that drummers control the bounce frequency by modulating grasp force, which in turn controls the effective stiffness of the drumstick in its interaction with the drum head. The results demonstrate that modulation of passive impedance can permit a low bandwidth manipulator, human or robot, to execute certain types of fast manipulation tasks. |