Path Following for Robot Manipulators Using Gyroscopic Forces
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Date
2017-08-23
Authors
Wei, Nan
Advisor
Jeon, Soo
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
This thesis deals with the path following problem the objective of which is to make the end
effector of a robot manipulator trace a desired path while maintaining a desired orientation.
The fact that the pose of the end effector is described in the task space while the control
inputs are in the joint space presents difficulties to the movement coordination. Typically,
one needs to perform inverse kinematics in path planning and inverse dynamics in movement
execution. However, the former can be ill-posed in the presence of redundancy and
singularities, and the latter relies on accurate models of the manipulator system which are
often difficult to obtain.
This thesis presents an alternative control scheme that is directly formulated in the
task space and is free of inverse transformations. As a result, it is especially suitable
for operations in a dynamic environment that may require online adjustment of the task
objective. The proposed strategy uses the transpose Jacobian control (or potential energy
shaping) as the base controller to ensure the convergence of the end effector pose, and
adds a gyroscopic force to steer the motion. Gyroscopic forces are a special type of force
that does not change the mechanical energy of the system, so its addition to the base
controller does not affect the stability of the controlled mechanical system. In this thesis,
we emphasize the fact that the gyroscopic force can be effectively used to control the pose
of the end effector during motion. We start with the case where only the position of
the end effector is of interest, and extend the technique to the control over both position
and orientation. Simulation and experimental results using planar manipulators as well as
anthropomorphic arms are presented to verify the effectiveness of the proposed controller.