Application of Stewart Platform as a Haptic Device for Teleoperation of a Mobile Robot

Abstract

In this study, a haptic device based on a Stewart Platform is developed by a dual-loop position-based admittance control. The admittance control is a common technology used in the haptic interface, which has two control loops. An outer loop transforms a force to the desired position and orientation, which is called an admittance model. An inner position loop based on a fault-tolerant control is used to ensure that the movement of the haptic device follows the reference trajectory resulting from the admittance model. The fault-tolerant control in this research is a combination of Nonsingular Fast Terminal Sliding mode control (NFTSMC) with an improved reaching law and an Extended State Observer (ESO), which is used to estimate and compensate for disturbances, uncertainties, and faults in the system. The ESO mentioned in this paper can reduce the peaking value and enhance the tolerance ability to measurement noise compared to the traditional ESO. Accordingly, this fault-tolerant control will enhance the performance of the system under uncertainties, disturbances, and make the haptic handle move smoothly even in the presence of faults in the system. Finally, the haptic device is applied for teleoperation of a mobile robot with force feedback that helps the operator prevent the robot from colliding obstacles and improve the task performance. The experimental results demonstrate the effectiveness of the proposed system.