Finger Force and Touch Feedback Issues in Dexterous Telemanipulation

Multifingered robotic hands, when used as the slave end effectors in teleoperation, have some advan- tages over the conventional parallel jaw grippers. Effec- tive teleoperation of such end effectors raises the prob- lem of using suitable master devices. The most appropri- ate master devices for this purpose are the instrumented gloves and the hand exoskeletons. When using such mas- ter devices, either for telemanipulation of objects or for interacting with virtual worlds, it is crucial to the success of the task that the human operator "feels" the grasping and manipulating forces exerted by the slave robotic fin- gers. This requires that the slave hand fingertip forces as well as the tactual sensations be fedback to the hu- man operator's fingers via the dexterous master. This paper thus has two goals. The first goal is to iden- tify and analyze some specific requirements on the design of dexterous master devices meant for teleoperating mul- tifingered robotic hands, within this context of finger force feedback. The requirements are of 2 categories: construc- tional and functional. The constructional issues consist of the isomorphism, portability, motion range capabil- ity, and accommodation for human hand size variability. The functional issues consist of the bandwidth compat- ibility with the human hand, which itself has asymmet- ric input/output characteristics, the proprioceptive (force limit) compatibility, and the consideration of the psycho- metric stability of the human hand in sensing force magni- tudes and variations. Also of importance is the sensitivity of the master device that must be more than that of the human hand. Also evaluated in this paper are the 14 existing designs of hand masters to see how well they satisfy the afore stated constructional and functional requirements. Only 6 are capable of feeding back the slave finger forces to that of the operator while none of them completely satisfy all the requirements listed above. Hence described at the end is a new design of a force feedback master aimed at satis- fying the requirements. Its fabrication and experimental demonstration, however, remain to be performed. The second goal of this paper is to evaluate the state-