Motion constraint design for a multi-functional virtual manipulation system

Simulation systems nowadays are applied for various tasks, and thus demands a versatile manipulative system for the user to interact with the corresponding simulated environments. To make a single manipulative device applicable for different tasks, the concept of virtual mechanism has been previously proposed, in which virtual motion constraints are constructed via the software to constrain the manipulative device to move within a limited workspace that corresponds to task requirements. Motivated by the idea, in this paper, we propose a systematic approach to design and implement the virtual motion constraints for a multi-functional virtual manipulation system. The motion constraints are generated from sets of virtual walls, built of different shapes and physical properties, to deal with the compliance task, which involves both position and force management. An algorithm on how to properly assemble the walls and a graphics-based method for smooth force rendering between them are proposed for given compliance tasks. For demonstration, in experiments, we implement a virtual omni-directional wrench based on using a 2-DOF force-reflection joystick.