A Cooperative Framework For Precise Hand-Held Manipulation ( Tentative Title )

This work explores a hierarchical approach for “natural” cooperative manipulation. Although the concepts apply to all manipulator systems (including tele-operated systems), the scope of this investigation is limited to specially designed hand held surgical robots. By “natural” we mean a high degree of transparency in operation of the device. Hand held robots are usually controlled in compliance to a force sensor. Special features in surgical robots include improved safety and higher accuracy. Why is this important? Complex interfaces and difficulty in encoding intelligence in robots has hindered their application. An approach that leaves the user in control, and at the same time removes some of their deficiencies is likely to be easier to implement, find easier acceptance and still be applicable for a large subset of manipulation tasks. This requires augmentation of compliant control with additional sensory information. Augmented manipulation is defined as robotic manipulation with a human master providing sensory and planning inputs. It may also be possible to encode some information extracted from previous/taught motions to more effectively interpret the user input. The core issues in this problem are a) understanding the motion being made (or specifying it in some way) b) designing control strategies for efficiently integrating the sensory feedback, c) integrating non-sensory information (planning information, constraints etc.), d) evaluating human performance with and without augmentation. Each of these problems is large in its general form and perhaps beyond the scope of this work. A more time bound and tractable formulation of the problem is the following: Generate a set of generic robust primitives, and ways to combine them to transparently implement explicit specifications of a simple manipulation task This reduces the core issues to: a) creating robust primitives for common motions ( and ways to compose them), b) implementing control strategies suitable for these primitives, c) integrating explicit representations of non sensory information in the control, d) evaluating human performance with and without augmentation for implemented tasks. The domain of this problem is motions made by a surgical robot under direct surgeon guidance. A subset of motions made during surgery are similar to assembly analogues, such as positioning a tool to the surgical site ( to the peg in hole) thus some inferences could be drawn from work in assembly environments. However, due to complex interactions with the environment and increased safety requirements they differentiate from assembly tasks where the problem may be a little easier due to limited cost of an error and constrained environments. Further, we are primarily interested in manipulation tasks with a degree of contact compliance between the tool and the environment being manipulated. Usually, these are relatively low information bandwidth tasks with moderately small force ranges. The environment interaction ( i.e. tool tip) forces can require special instrumentation, but this is being developed concurrently. The main contribution of this work is expected to be a framework for performing simple manipulation tasks in environments with detectable discontinuities. Side contributions could include implementation for the “steady hand” robots, and application to some suitable tasks for validation.