T. Umeno et al., ROBUST SERVOSYSTEM DESIGN WITH 2 DEGREES OF FREEDOM AND ITS APPLICATION TO NOVEL MOTION CONTROL OF ROBOT MANIPULATORS, IEEE transactions on industrial electronics, 40(5), 1993, pp. 473-485
In this paper, we propose a novel robust servosystem design method bas
ed on the two degrees of freedom (TDOF) controller and its application
to the advanced motion control for a robot manipulator. This servosys
tem is derived from the simple parametrization. It has the remarkable
feature that the command input response and the closed loop characteri
stics can be specified independently by using two parameters which bel
ong to the ring of stable and proper rational functions. We can determ
ine the sensitivity and the complementary sensitivity functions straig
htforwardly through the optimization of the two design parameters. The
control performances of our servosystem are shown by laboratory exper
iments. Next, by applying the TDOF position servosystem, we realize th
e completely decentralized joint control system of multi-axis robot ma
nipulators. We do not need to take care of the influence of various ki
nds of dynamical forces, i.e., the centrifugal, Coriolis, and gravity
forces, payload torque and even the frictional torque because they are
sufficiently suppressed by the robust servomechanism at each joint. F
urthermore, since there are no need to perform any coordinate transfor
mations with respect to the speed and acceleration, the structure of o
ur controller is extremely simple. This means that we do not need the
complicated calculation of inverse dynamics which has been inevitable
for high-speed control of robot manipulators. We realize various kinds
of robot motion controls such as compliance, force, and hybrid contro
ls in a unified way based on the robust position control. We implement
our idea by using DSP and confirm their efficacy by laboratory experi
ments with respect to trajectory, compliance, and hybrid controls.