Comparison of Seven Performance Measures in a Time-Delayed Manipulation Task

Real-time performance data was collected during a pick-up task carried out with a Rancho master-slave manipulator using a minicomputer-based data taker. Motions on all seven master and all seven slave joints as well as instantaneous electrical power consumed were continuously monitored. In addition to the usual task-time measurements, computer algorithms to integrate the energy consumed and to count and time the number of moves were implemented. In addition to these measures, several derived measures such as the fraction of time moving (MRATIO) and mean time per move (MBAR) were obtained in an off-line analysis. A major goal of these experiments is to compare the seven different measures of performance to determine which are best for evaluating particular experimental conditions. Preliminary results of the time delay experiment indicate that two new measures, MRATIO and MBAR, are almost an order of magnitude more sensitive than task time, the conventional measure, in determining performances changes with transmission delays in the range from 0.0 to 1.0s. Taking advantage of the operator's move-and-wait strategy, we also show how the energy consumed in carrying out a task can be reduced by a factor of three in the one-second transmission-delay case.