On-line multi-criteria based collision-free posture generation of redundant manipulator in constrained workspace

Abstract

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.

Trajectory planning for a planar macro-micro manipulator of a laser-cutting machine

“…Among these, self-motion of the redundant manipulator, as termed by Nakamura (1991), is used to achieve subtasks. Redundancy resolution to distribute the total motion to redundant axes in velocity level by making use of pseudo-inverse approaches has been widely used in regulating self-motion for singularity avoidance by Yoshikawa (1984), joint velocity minimization by Seraji (1991), obstacle avoidance by Chen et al (2002), mechanical joint limit avoidance by Tatlicioglu et al (2009) and manipulability by Maaroof et al (2012). The commonality of these approaches is that the extra links that make the manipulator redundant are similar in term of kinematic and dynamic capabilities of the previous links.…”

A New Objective Function for Obstacle Avoidance by Redundant Service Robot Arms

“…In another formulation by [13], the square of the minimum distance is used as an objective function. One alternative approach is to use the reciprocal of the minimum distance, as in [14].…”

“…In view of the closed-loop null space velocity tracking error in (15), the auxiliary controller in (13) ensures that the joint velocities in the null space converge to (…”

Trajectory Planning of Redundant Planar Mechanisms for Reducing Task Completion Duration

“…Redundancy resolution algorithms that allow the ability to optimize for various criteria using subtask controllers have been proposed in literature. Redundancy resolution in velocity making use of pseudo-inverse approaches has been widely used in various subtask controls such as singularity avoidance (Yoshikawa, 1984), joint velocity minimization (Seraji, 1991), obstacle avoidance (Chen et al, 2002), mechanical joint limit avoidance (Tatlıcıoğlu et al, 2009), and manipulability (Maaroof et al, 2012). In addition, different redundancy resolution approaches have been proposed including in velocity level (Rajiv et al, 1991) and in acceleration level (Wang et al, 2010).…”