Z. Shiller et H. Chang, TRAJECTORY PRESHAPING FOR HIGH-SPEED ARTICULATED SYSTEMS, Journal of dynamic systems, measurement, and control, 117(3), 1995, pp. 304-310
This paper presents a method for reducing the tracking errors of artic
ulated systems, moving along specified paths at high speeds. It consis
ts of preshaping the reference trajectory to account for the dynamics
of the feedback controller. The trajectory is assumed to be feasible,
satisfying the known manipulator dynamics and the actuator constraints
. The correction term, added to the nominal trajectory, is computed by
filtering the nominal control inputs through the inverse of the feedb
ack controller. A learning procedure is also presented to account for
unknown parameters of the feedback controller and for unmodeled dynami
cs. It consists of an iterative parameter optimization that minimizes
the tracking error along the path at each joint. The initial guesses f
or this optimization are selected to ensure that the tracking error is
not worse than the error with no preshaping. The method is demonstrat
ed experimentally for the UCLA Direct Drive Ann and for the AdeptOne i
ndustrial robot, achieving mean tracking errors as low as 0.11 mm at t
op speeds of 1.8 m/s.