Workspace Modeling and Analysis for Dexterous Hands
International Journal of Humanoid Robotics Volume 12, Issue 01, March 2015 (doi: 10.1142/S0219843615500061)
The workspace is a fundamental feature for a dexterous hand to grasping plan, motion control, and mechanical design. Although the graphic, numerical, or analytical methods are valid to generate the workspace of dexterous hands, but there exist several defects for these methods to describe the workspace characteristics, such as forms, boundaries, volumes, and intersection workspaces. We propose a combined modeling approach to visualize and analyze the workspace of YWZ dexterous hand, which has 5 fingers, 20 degrees of freedom (Dofs). The proposed approach is also fit for similar dexterous hands to generate their precise workspaces. After a brief mechanism introduction of YWZ dexterous hand, a displacement equation of its index finger is deduced to calculate the fingertip positions in three-dimension (3D) Euclidean space. Then, a two-dimension (2D) boundary figure enclosing the flexion-extension motion field of the finger is drawn by the displacement equation. Taking this boundary figure as a sketch in a CAD modeling environment, we further model a vivid 3D finger workspace, which is relative with the abduction-adduction motion of the finger. Besides, we generate the whole workspace of YWZ dexterous hand and analyze its volumes and intersection workspaces. The kinematic simulations and physical prototype experimentations are carried out to validate this approach can construct perfect workspace of dexterous hands. Compared with the Monte Carlo method, the form and boundary of the 3D finger workspace generated by our proposed approach have more accurate, integrated, vivid, and intuitional.
Keywords: Workspace; Dexterous hands; Numerical methods; Kinematic simulations.