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Emulating on Earth the weightlessness of a manipulator floating in space requires knowledge of the manipulator's mass properties. A method for calculating these properties by measuring the reaction forces and moments at the base of the manipulator is described. A manipulator is mounted on a six-degree-of-freedom sensor, and the reaction forces and moments at its base are measured for different positions of the links of the manipulator as well as for different orientations of its base. A procedure is developed to calculate from these measurements some combinations of the mass properties of the manipulator. The mass properties identified are not sufficiently complete for computed torque and other dynamic control techniques, but do allow compensation for the gravitational load on the links of the manipulator, and for simulation of weightless conditions on a space emulator. The algorithm has been experimentally demonstrated on a PUMA 260 and used to measure the independent combinations of the sixteen mass parameters of the base and three proximal links of the manipulator. >

Programming by human demonstration is an intuitive method of robot programming, in which the programmer demonstrates how a task is performed using a human/robot teaching device that measures human motion, and the data gathered is used to generate the robot program. A direct duplication of the demonstrated trajectory would result in unnecessary robot motion due to human "wiggles" and unintended motion. To identify a more satisfactory robot trajectory, a method is presented that uses multiple demonstrations of the same task. Variation in human trajectories between trials is attributed to human inconsistency and is used to define an obstacle free region, by applying the Jordan curve theorem. The shortest path within the obstacle free region is determined, resulting in a shorter robot path than any of the demonstrations. Thus the presence of human inconsistency is used to improve robot performance. The analysis is restricted to planar translational motion. >