Estimating the minimum grip force required when grasping objects under impulsive loading conditions

As an aid to studying the efficiency of grip force scaling in the context o f collisions, we present a simple cost-effective approach to estimating the slip ratio-that is, the minimum grip-to-load-force ratio needed to prevent object slippage. The grip apparatus comprises a sturdy load cell to measur e grip force and two linear potentiometers to provide detailed description of finger movements. The slip ratio was estimated by plotting the magnitude of finger movement against the grip-to-load-force ratio at the time of imp act. The slip ratio was dependent on the direction of loading, which stress es the importance of estimating slip ratios in a context similar to that of the experiment in which the efficiency of subjects' behavior is to be asse ssed.