Multilateral Teleoperation With New Cooperative Structure Based on Reconfigurable Robots and Type-2 Fuzzy Logic

Abstract

This paper develops an innovative multilateral teleoperation system with two haptic devices on the master side and a newly designed reconfigurable multi-fingered robot on the slave side. A novel nonsingular fast terminal sliding-mode algorithm, together with varying dominance factors for cooperation, is proposed to offer this system's fast position and force tracking, as well as an integrated perception for the operator on the reconfigurable slave robot (manipulator). The Type-2 fuzzy model is used to describe the overall system dynamics, and accordingly a new fuzzy-model-based state observer is proposed to compensate for system uncertainties. A sliding-mode adaptive controller is designed to deal with the varying zero drift of the force sensors and force observers. The stability of the closed-loop system under time-varying delays is proved using Lyapunov-Krasovskii functions. Finally, experiments to grasp different objects are performed to verify the effectiveness of this multilateral teleoperation system.

Single Master Bimanual Teleoperation System With Efficient Regulation

“…3). Unlike the previous studies [33]- [36] that require multiple masters to separately coordinate the slaves' forces, the proposed system enables the slaves to mutually apply and balance their forces in reasonable directions. Following the human reference force from the master, the slave robots can smoothly and stably contact the task object.…”

“…In this section, we discuss how to derive the transmitted reference force F htr , F e2tr and F e1tr for further force controller setup. For the force control during decoupled motion, due to the different positions and orientations of the robots, simultaneously transmitting the human force to all the slave robots and simultaneously feeding all the slave's force back to the master as in [16], [33] is likely to apply inaccurate force to the task, and the operator may obtain unreal force feedback. In fact, the bimanual slave robotic system can be imagined as the two hands of our bodies.…”

“…At the same time, force control and feedback are also crucial to a bimanual teleoperation system, without which the system cannot make a transient response to the changing environment or provide a good force feedback to the operator [32]. As outlined in [9], [33], the difficulty of designing force control algorithms in a bimanual teleoperation system, is much greater than that in an ordinary teleoperation system for the following two reasons. First, unlike a single slave in bilateral teleoperation, a good force control algorithm in bimanual teleoperation must be able to build a bridge among the slaves to adaptively regulate and balance their forces in the correct directions on the task object.…”

“…Significant contributions to force control in bimanual teleoperation systems have been developed in some studies. In [33], a force-based sliding mode controller with variable dominance factors was proposed that allows the operator to use multiple masters to drive the grippers for grasping irregular-shaped objects. In [34], [35], force observer-based controllers were proposed to enhance the local force control of a dual-masterbimanual teleoperation system, which was further improved for environmental compliance by adding impedance control in [36].…”

“…POFDS denotes the strategy for deriving the desired positions, orientations and forces; SMC denotes sliding mode control; VC denotes velocity controller, FC denotes force controller; PCv denotes the position controller with a variable gain; P d , O d , and F d denote desired positions, orientations, and forces, respectively; P , O, and F denote actual positions, orientations, and forces, respectively structures, number of joints, dynamics and kinematics of the masters and the slaves differ. An SMBT system is usually more user-friendly for a single operator than multimaster bimanual teleoperation systems in [33]- [36], since the operator only needs to control one master. However, as analyzed above, most of the existing bimanual teleoperation systems focus on motion synchronization of slave robots under time delays, uncertainties and constraints, but a complex task usually needs to be performed by more than one slave robot with different motions and variable orientations and with balanced forces in correct directions, which basically cannot be performed by using those previous approaches.…”