Suboptimal Anatomy of Metamorphic Manipulators Based on the High Rotational Dexterity
This paper presents a method for the task based determination of the suboptimal anatomy of a metamorphic manipulator considering tasks with varying orientation of the end effector. A performance index representing the orientation dexterity along the rotational motion of the end effector based on max min of the rotational manipulability is formulated. In addition, a method based on the screw motion and dual vectors representation is proposed for the determination of the Denavit Hartemberg (D H) parameters of each metamorphic link between two successive active joints and the relative homogeneous transformation matrix as a function of the pseudo joint angles. Thus the dependence of the kinematics of the manipulator and of the performance index on the pseudojoint angles is determined to be used in the searching of the sub optimal anatomy for the given task, since in metamorphic manipulators each anatomy of a given structure is defined parametrical by the pseudojoint angle values. The proposed approach is tested and demonstrated using a metamorphic manipulator structure with six active joints and four pseudojoints. The rotational velocity performance between the sub optimal and an arbitrary anatomy is compared and discussed.