Deictic teleassistance

Abstract

We present a simple sign language for teleassistance inspired by the work of the Bernstein (1967) and by psychophysical evidence in hand-eye coordination. In our schema, a teleoperator uses hand signs to guide an otherwise autonomous robot manipulator through a given task. Each sign signals a context switch and provides a hand-centered reference frame for the robot's servomotor routines. The signs are natural, such as pointing to an object to indicate the desire to reach toward it as well as the axis along which to reach. These signs are called deictic from the Greek word for pointing to stress their indicative and relative nature. The task example is opening a door using a Utah/MIT hand mounted on a Puma 760 arm. The teleoperator wears an EXOS hand master and polhemus sensor. Three variations of nearest neighbor pattern classification are tested for online recognition of the sign language. The simplest, in which the operator signs each pose once before starting, is the best for this task. The dual-control strategy of teleassistance combines teleoperation and autonomous servo control to their advantage. The use of a symbolic sign language helps to alleviate many problems inherent to literal master/slave teleoperation. Conversely, the integration of global operator guidance and hand-centered coordinate frames permits the servo routines to position the robot in relative coordinates and interpret feedback within a constrained context, significantly simplifying the computation and reducing the need for detailed task models.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>