Abstract: We propose a behavioral construct termed a "virtual tool" that allows many of the advantages of high-degree-of-freedom robotic systems to be realized without excessive comuptational costs or modeling requirements. The basic idea of a virtual tool is drawn from the observation that the most efficient way of performing a task is generally to use a device that is specially designed for it. This suggests that a way to use redundant dgrees of freedom in a system is to use them to customize the system so that it becomes, in essence, a special-purpose tool for the task at hand. We call the resulting instantiation a virtual tool. Formally, this tailoring takes the form of implementing constraints on the degrees of freedom of the system through lower-level control processes. Remaining degrees of freedom appear as control parameters of the virtual tool, and can be used by higher-level processes, or by a human teleoperator, to control the system.
We present experimental results showing the application of the virtual tool approach to telemanipulation using a 22-degree-of-freedom hand-arm system. Our chosen task is a fairly conmplex assembly task requiring the robot to pick up a small object, transport it, and insert in into a hole with matching shape. Instead of attempting to map the configuration of the teleoperator's hand-arm system to the robot using a dataglove or similar device, we provide basic parameterized grasping and manipulation primitives (or virtual tools) that can be invoked by the teleoperator as he progresses through the stages of the complex task.