Towards A Compliant and Accurate Cooperative Micromanipulator using Variable Admittance Control

Abstract

Micro-scale operation is a challenging and time-consuming procedure for humans. With the involuntary motions like physiological hand tremor and jerks, operator's performance is limited and the inaccuracy increases the risk of damage to nearby tissues or products. A cooperative micromanipulator whose end-effector with the instrument is stiff in response to human's intended force is a potential solution to reduce the tremors and increase the accuracy of the operation. However, operating such a stiff micromanipulator is energy consuming in some particular operational path. For instance, it requires the operator to move the instrument with large force if a large operational path is desired. During tasks with large movements, compliance is often needed rather than accuracy. Hence, in this paper, we design a collaborative control that ensures compliance or accuracy of the operation based on human's intended motion. Particularly, a variable admittance controller is employed to achieve the best trade-off between compliance and accuracy. We use micro-suturing as an illustration and conduct the experiments. The experimental results verify the effectiveness of the control design and the improvement for performance of the micromanipulator.