Posture evaluation for mobile manipulators using manipulation ability, tolerance on grasping, and pose error of end-effector

摘要

This paper presents a method for determining the posture of a mobile manipulator aiming to reach a target end-effector pose. A posture is composed of two parameters: the pose of the mobile platform and joint angles of the manipulator. To determine the platform pose rationally, we propose a novel posture evaluation method focusing on the pose error associated with the end-effector and caused by the accumulated positioning error of the platform. The proposed method implies not only using the pose error of the mobile platform but also considering the manipulation ability of the end-effector, as well as the tolerance region for grasping an object by the end-effector. The evaluation results can be used to analyze the stability of postures in terms of grasping a target object. In addition, we introduce a search-based method to identify appropriate poses of the mobile platform. We also consider an application example of a two-link three-joint mobile manipulator. Using such a robot, we explain a concrete calculation method used to estimate the tolerance region, and then, show the simulation results corresponding to posture evaluation and pose determination.