Modelling and control of a robotic manipulator subject to base disturbances
Abstract
This thesis presents the modelling and control of a high gear ratio robotic manipulator
mounted on a heavier moving base which is subject to base disturbances. The manipulator
motion is assumed not to affect the base motion. The problem of a robotic manipulator on
a non-inertial base can be applied to operation on sea vessels or all-terrain vehicles, where
the base motion is unknown and cannot be used as a feed-forward signal to the model.
A dynamic model is derived for the PA10-6CE manipulator with the assumption of a fixed
base and the model terms are analysed numerically when comparing the simulation and
experimental results. Based on the obtained results a set of model based controllers is
compared to a basic proportional and derivative type controller to evaluate the trajectory
tracking gains and trade-offs.
The dynamic model is extended to the case of a manipulator on a moving base and numerical
comparisons of simulation and experimental results are used to verify the model
validity and the significance of the various model terms. From the results of this study
a set of model based controllers is obtained. A novel adaptive scheme is then proposed
for compensation of an unknown and varying gravity acceleration vector acting on the
manipulator base. Controllers based on using an additional sensor output are compared
with static and adaptive gravity controllers and the latter proved to be superior in terms of
trajectory tracking performance.