A Force Control of Multi-Degrees-of-Freedom Manipulator Based on Parameter Estimation.

Abstract

The paper describes an adaptive force controller. In general force controller, force response depends on unknown parameters of the environment which the manipulator contacts. In case the target environment is hard, the force response of common system is oscillatory. To obtain stable force response which is independent of environment, it is necessary to adjust control gain according to the environment.In the proposed method, a disturbance observer is applied to each joint and the total disturbance effects are canceled out in joint space. In the observer-based manipulator, full dynamics including the environment is cleared up and the workspace force controller is constructed without any disturbance effect. Then the least-squares estimator of unknown parameters of environment is also introduced to adjust the control gain. Several experimental results are shown to verify the proposed force controller.