ONLINE IMPROVEMENT OF SPEED AND TRACKING PERFORMANCE ON REPETITIVE PATHS

When a mechanism such as a robot executes a trajectory, the tracking e rror increases as the trajectory speed is increased. This paper report s the experimental evaluation of an algorithm which locally adjusts th e speed of a repetitive trajectory to achieve a specified level of tra cking error, In regions of the trajectory where error is too high, the trajectory is slowed down, in regions where the error is below the sp ecification, the trajectory is speeded up. The algorithm was experimen tally evaluated on a five-axis mini direct-drive robot and it stably c onverged to a satisfactory trajectory for a range of error levels and speeds in spite of wide variations in the key algorithm parameters, Th e method is independent of the splining method used to generate the tr ajectory and of the feedback control law, and no model of the system i s required.