History of Robotics Research and Development of Japan1985ManipulationDynamic Hybrid Control of Robot Manipulators

Tsuneo Yoshikawa

Kyoto University

For the application of robot manipulators to complex tasks, it is often necessary to control not only the position of a manipulator but also the force exerted by the end-effector on an object. For this purpose, Raibert and Craig have proposed the hybrid position/force control method. In this method, however, the manipulator dynamics has not been taken into account rigorously. The dynamic hybrid control approach described here takes the manipulator dynamics into consideration. Constraints imposed by the contact between the end-effector and the object are described by a set of constraint hypersurfaces. Then the basic equations for dynamic hybrid control are derived. It is shown that if the manipulator is not in a singular configuration, the desired position and force at the end-effector can be realized simultaneously and rigorously. The validity of the dynamic hybrid control approach was confirmed by an experiment shown by Photo, Fig.1, Fig.2, and Movie 1 given below. The formulation of the dynamic hybrid control method provides a theoretical basis for deriving hybrid control algorithms for various situations such as (1) hybrid control for the case of unknown constraint surfaces(Movie 2) , (2) cooperative hybrid control by multiple robot manipulators handling one common object (Movie 3) , (3) grasping and manipulation by a hand with multiple fingers, and (4) force control of flexible manipulators.

写真　動的ハイブリド　制御の実験装置 — Photo Experimental equipment

Fig. 1 Experiment (The given task is to control the end-effector position of a two-joint manipulator to follow a desired position trajectory that goes back and forth between points A and B on the vertical plane and the force exerted by the end-effector on the plane to follow a stepwise change between 10N and 20N.)

Fig.2 Result of experiment (The dotted chain curves are the desired trajectories and the solid curves are the real outputs. (a) is the case of dynamic hybrid control and (b) is the case of a simplified hybrid control without consideration of manipulator dynamics.)

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