Enhanced time delayed linear bilateral teleoperation system by external force estimation

Abstract

One of the prevalent methods in linear bilateral teleoperation systems with communication channel time delays is using position and velocity signals in the control scheme. Utilization of force signals in such controllers improves the performance significantly and reduces the tracking error. Measuring force signals in such cases is one of the major problems. In this paper, a control scheme in the presence of human and environment force signals for the linear bilateral teleoperation is proposed. Due to elimination of measuring forces in the control scheme, a force estimation approach based on disturbance observers has been utilized. The proposed approach guarantees asymptotic estimation of constant forces. The estimation error would only be bounded for time varying external forces. To cope with the variation of the human and environment force, a sliding-mode-controller is used. The stability and transparency condition in the teleoperation system with the designed control scheme is derived from absolute stability concept. The designed control scheme guarantees the stability of the teleoperation system in the presence of time varying human and environment forces. Experimental results show that the proposed control scheme improves position tracking in the free motion and in contact with the environment. In addition, the force estimation approach appropriately estimates human and environment forces.

Adaptive Finite-Time Control Scheme for Teleoperation With Time-Varying Delay and Uncertainties

“…The time delays of the system are the same as the setting in the above simulation part. The RBFNN is used to estimate the unknown dynamic and uncertainties In addition, the parameters of master and slave controllers are set as (50,50,50), λ m2 = λ s2 = diag (35,45,45), σ m1 = σ s1 = 1.2, σ m2 = σ s2 = 0.9, σ = 0.3, a m1 = a m2 = a s1 = a s2 = 5, K m1 = K m2 = K s1 = K s2 = diag(70, 90, 90), m1 = s1 = diag(0.9, 0.9, 0.9), m2 = m3 = s2 = s3 = 0.9.…”

“…In [49], the torque error is introduced to construct the auxiliary function, and adaptive control scheme with position/torque tracking control are, respectively, developed. In [50]- [54], differential algorithms have been developed to estimate the environment force and external force, which are utilized for force compensating control. In [55], the SALS method is introduced to identify the parameters of dynamic and environment.…”

Design an impedance control strategy for a teleoperation system to perform drilling process during spinal surgery

“…Absolute stability is employed to investigate stability and performance analysis of the closed-loop teleoperation system (Amini et al, 2015). Absolute stability is one of the conventional methods to analyze linear teleoperation systems stability (Amini et al, 2013). Since the absolute stability method is a straightforward device to analyze closed-loop linear teleoperation, therefore it could be utilized to analyze the performance and stability of the presented teleoperation system.…”

“…In order to employ an absolute stability concept, the mentioned teleoperation system should be represented in the two port condition (Amini et al, 2013). A two port network includes two inputs and two outputs.…”

A passivity-based control strategy for nonlinear bilateral teleoperation employing estimated external forces

“…Another issue associated with this mentioned method is that using this algorithm could not guarantee closed-loop teleoperation systems stability. A modified sliding-mode control strategy including force estimation approach was designed for linear bilateral teleoperation systems [18,19]. Based on the proposed control scheme, it was proven that the force estimation error is bounded.…”