Dual-drive force/velocity control: implementation and experimental results

The authors present the dual-drive control concept, which is a form of hybrid force/velocity control in which the constraint frame is automatically determined from feedback information. This allows compliant tasks to be conveniently specified in terms of a desired (normal) force and a desired (tangential) velocity. The proposed control algorithm is appropriate for compliant tasks that require motion orthogonal to the contact force; for example, turning a crank or tracking a surface. These basic tasks can be performed without the continuous involvement and corresponding overhead of a high-level planner. This is accomplished by the definition of a plane on which compliant motion is to occur and a point with which force and velocity directions are determined. The dual drive controller has been implemented on the SIERA system and is being used to control an IBM 7565 robot. Experimental results for crank-turning and surface-tracking problems are provided to illustrate the algorithm