Updating Virtual Fixtures From Exploration Data in Force-Controlled Model-Based Telemanipulation

This paper proposes an approach for using force-controlled exploration data to update and register an a-priori virtual fixture geometry to a corresponding deformed and displaced physical environment. An approach for safe exploration implementing hybrid motion/force control is presented on the slave robot side. During exploration, the shape and the local surface normals of the environment are estimated and saved in an exploration data set. The geometric data collected during this exploration scan is used to deform and register the a-priori environment model to the exploration data set. The environment registration is achieved using a deformable registration based on the coherent point drift method. The task-description of the high-level assistive telemanipulation law (virtual fixture) is then deformed and registered in the new environment. The new model is updated and used within a model-mediated telemanipulation framework. The approach is experimentally validated using a da-Vinci research kit (DVRK) master interface and a Cartesian stage robot. Experiments demonstrate that the updated virtual fixture and the updated model allow the users to improve their path following performance and to shorten their completion time when the updated path following virtual fixture is applied. The approach presented has direct bearing on a multitude of surgical applications including force-controlled ablation.