Transparency Improvement by External Force Estimation in a Time-Delayed Nonlinear Bilateral Teleoperation System

Abstract

Teleoperation systems have been developed in order to manipulate objects in environments where the presence of humans is impossible, dangerous or less effective. One of the most attractive applications is micro telemanipulation with micropositioning actuators. Due to the sensitivity of this operation, task performance should be accurately considered. The presence of force signals in the control scheme could effectively improve transparency. However, the main restriction is force measurement in micromanipulation scales. A new modified strategy for estimating the external forces acting on the master and slave robots is the major contribution of this paper. The main advantage of this strategy is that the necessity for force sensors is eliminated, leading to lower cost and further applicability. A novel control algorithm with estimated force signals is proposed for a general nonlinear macro–micro bilateral teleoperation system with time delay. The stability condition in the macro–micro teleoperation system with the new control algorithm is verified by means of Lyapunov stability analysis. The designed control algorithm guarantees stability of the macro–micro teleoperation system in the presence of an estimated operator and environmental force. Experimental results confirm the efficiency of the novel control algorithm in position tracking and force reflection.

Control of teleoperation systems in the presence of cyber attacks: A survey

“…Various methodologies were proposed to handle control issues in several applications of teleoperation systems. Some examples are: nonlinear trilateral teleoperation systems [42], PD-like controller [43], four-channel structure [44], operator dynamics considerations [45], output feedback with force estimation [46], a stable and transparent microscale teleoperation [47], external force estimation [48], position synchronization [49], and new stability criteria using hybrid strategies of position and impedance reflection [50].…”

“…Also,q i ,q i , q i ∈ R n are the angular acceleration, velocity, and position, respectively, M i (q i ) ∈ R n×n is the inertia matrix, C i (q i ,q i ) ∈ R n×n is the centrifugal and Coriolis matrix, G i (q i ) ∈ R n is the gravitational torque, τ i ∈ R n is the robot control input, and τ h , τ e ∈ R n are torques exerted by the human operator and the environment, respectively. When there is no attack (q i =q i ,q i = q i ), the following PD-like controller can be adopted for BTS shown in (48):…”

“…where K d , K p , K dm ∈ R + . For the BTOS with a PD-like control method represented in Figure 9, the attacker can affect the system by FDI attacks, which can intelligently replace the signals (q T i , q T i ) T being exchanged by the robots with (q T i ,q T i ) T for i = m, s. For BTS, the DFDIA is discussed with respect to a specific form of storage function represented by ( 49 In 2016, Dong, Gupta and Chopra [150] For a BTOS with dynamics (47) controlled by (48). A FDI attack that changes the states being transmitted between the robots of the BTSs as ( 50):…”

Output feedback assistive control of single-DOF SEA powered exoskeletons

“…The linear 1-DOF mass-spring-damper system is widely used in teleoperation and haptic studies for modeling the physical or virtual environments. This model is even used as a representation of the human operators (Amini et al, 2015;Fite et al, 2004;Lee and Spong, 2006;Sirouspour and Shahdi, 2006;Lawrence and Chapel, 1994;Vander Poorten et al, 2006;Focchi et al, 2016).…”