The manipulator with a large degree of
redundancy is useful for realizing multiple tasks such as maneuvering
the robotic arms in the constrained workspace, e.g. the task
of maneuvering the end-effector of the manipulator along a pre-specified
path into a window. This paper presents an on-line technique
based on a posture generation rule to compute a null-space
joint velocity vector in a singularity-robust redundancy resolution method. This
rule suggests that the end of each link has to
track an implicit trajectory that is indirectly resulted from the
constraint imposed on tracking motion of the end-effector. A proper
posture can be determined by sequentially optimizing an objective function
integrating multiple criteria of the orientation of each link from
the end-effector toward the base link as the secondary task
for redundancy resolution, by assuming one end of the link
is clamped. The criteria flexibly incorporate obstacle avoidance, joint limits,
preference of posture in tracking, and connection of posture to
realize a compromise between the primary and secondary tasks. Furthermore,
computational demanding of the posture is reduced due to the
sequential link-by-link computation feature. Simulations show the effectiveness and flexibility
of the proposed method in generating proper postures for the
collision avoidance and the joint limits as a singularity-robust null-space
projection vector in maneuvering redundant robots within constrained workspaces.
Obstacle Avoidance, Visual Detection Performance, and Eye-Scanning Behavior of Glaucoma Patients in a Driving Simulator: A Preliminary Study
