F. Khorrami et S. Jain, NONLINEAR CONTROL WITH END-POINT ACCELERATION FEEDBACK FOR A 2-LINK FLEXIBLE MANIPULATOR - EXPERIMENTAL RESULTS, Journal of robotic systems, 10(4), 1993, pp. 505-530
Experimental results for end-point positioning of multi-link flexible
manipulators through end-point acceleration feedback are presented in
this article. The advocated controllers are implemented on a two-link
flexible arm developed at the Control/Robotics Research Laboratory at
Polytechnic University. The advocated approach in this article is base
d on a two-stage control design. The first stage is a nonlinear O(1) f
eedback linearizing controller corresponding to the rigid body motion
of the manipulator. Because this scheme does not utilize any feedback
from the end-point motion, significant vibrations are induced at the e
nd effector. To this effect, and to enhance the robustness of the clos
ed-loop dynamics to parameter variations, the inner loop is augmented
with an outer loop based on a linear output LQR design that utilizes a
n end-point acceleration feedback. The forearm of the manipulator is s
ignificantly more flexible as compared with the upper arm. Experimenta
l and simulation results validate the fact that the end-effector perfo
rmance is significantly better with the proposed O(1) feedback lineari
zing control as compared with the linear independent joint PD control.
In addition, the nonlinear control offers other advantages in terms o
f smaller and smoother actuator torques and reducing the effects of no
nlinearities. Close conformation between simulation and experimental r
esults validates the accuracy of the model.