Path trajectory verification for robot manipulators in a manufacturing environment

Abstract

In a manufacturing environment where a robotic arm is programmed to follow a specified trajectory such as in welding, painting and soldering, it is often the case that the arm reaches a singular configu- ration, where the programme is stopped, the arm is switched to a new configuration and the motion is continued. This difficulty has been a long-standing problem. This paper presents a mathematical formulation for verifying whether a trajectory can be completed, uninterrupted, avoiding halting of a planned path. In some cases, this formulation also allows the selection of an initial configuration to ensure a smooth path trajectory. The paper presents an analytical formulation for determining barriers to motion inside the workspace of manipulator arms. Crossability analysis of the end-effector on a barrier is addressed. A criterion for selecting an initial configuration that would result in an uninterrupted motion is introduced. The mathematical theory is validated through numerical examples of planar and spatial manipulator arms.

Keywords

trajectory planning robot singularities trajectory verification robot path manipulator kinematics

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