J. Heilig et J. Mcphee, Determination of minimum-time maneuvers for a robotic manipulator using numerical optimization methods, MECH STRUCT, 27(2), 1999, pp. 185-201
The productivity of automated production lines depends on the velocities of
operating robot manipulators. Hence, time-optimal control for working cycl
es of robot manipulators are of decisive importance. In this paper, the min
imum-time retraction of a robot arm, subject to gravity and suspended on a
prismatic-rotational joint, is investigated. Iterative integration methods
using a B-spline representation for the actuator force and torque, a Runge-
Kutta integration method, and a sequential quadratic programming optimizati
on algorithm are used to calculate the time-optimal control and trajectorie
s. Results show that nonlinear gravity and centrifugal effects are exploite
d very effectively, to obtain minimum-time maneuvers from an initial to a f
inal state. These states also determine the switching structures of the con
trol. It is demonstrated that even the simple retraction of a robot arm pro
duces unexpectedly complex time-optimal solutions.