Stability is a major problem with bilateral teleoperator when there is a transmission time delay. By adding adequate damping gain into position servo, a stable bilateral control can be achieved under the existence of time delay. However, large damping gain is required to stabilize the system and the performance is degraded. In this paper, the performance improvement by introducing a high-pass filter into a proportional derivative-based teleoperator with time delay has been studied. We proposed new control law and derived the stability condition. We demonstrated the performance improvement using a hybrid matrix, 1-degree of freedom (DOF), 2-DOF simulations, and 2-DOF peg-in-hole experiments.

It is well known that the sense of presence in a tele-robot system for both home-based tele-rehabilitation and rescue operations is enhanced by haptic feedback. Beyond several advantages, in the presence of communication delay haptic feedback can lead to an unstable teleoperation system. During the last decades, several control techniques have been proposed to ensure a good trade-off between transparency and stability in bilateral teleoperation systems under time delays. These proposed control approaches have been extensively tested with teleoperation systems based on identical master and slave robots having few degrees of freedom (DoF). However, a small number of DoFs cannot ensure both an effective restoration of the multi-joint coordination in tele-rehabilitation and an adequate dexterity during manipulation tasks in rescue scenario. Thus, a deep understanding of the applicability of such control techniques on a real bilateral teleoperation setup is needed. In this work, we investigated the behavior of the time-domain passivity approach (TDPA) applied on an asymmetrical teleoperator system composed by a 5-DoFs impedance designed upper-limb exoskeleton and a 4-DoFs admittance designed anthropomorphic robot. The conceived teleoperation architecture is based on a velocity–force (measured) architecture with position drift compensation and has been tested with a representative set of tasks under communication delay (80 ms round-trip). The results have shown that the TDPA is suitable for a multi-DoFs asymmetrical setup composed by two isomorphic haptic interfaces characterized by different mechanical features. The stability of the teleoperator has been proved during several (1) high-force contacts against stiff wall that involve more Cartesian axes simultaneously, (2) continuous contacts with a stiff edge tests, (3) heavy-load handling tests while following a predefined path and (4) high-force contacts against stiff wall while handling a load. The found results demonstrated that the TDPA could be used in several teleoperation scenarios like home-based tele-rehabilitation and rescue operations.

In some strains of current philosophy, there is a growing interest in the passive and receptive aspects of the human condition. This interest is often paired with a criticism that ‘Western’ philosophy unduly neglects those aspects because of an ‘agential bias.’ This criticism has also been directed against the philosophy of Charles Taylor. I try to show that this criticism has some force in principle but is not plausible in the case of Taylor. First, I analyse John Rawls’ hugely influential concept of a life plan and show how this ‘agential bias’ applies here. Second, I argue that such a bias does not apply to Taylor’s The Language Animal by showing how active and passive moments are interwoven in his concepts of articulation and narration.

The possibility of operating in remote environments using teleoperation systems has been considered widely in the control literature. This paper presents a review on the discrete-time teleoperation systems, including issues such as stability, passivity and time delays. Using discrete-time methods for a master-slave teleoperation system can simplify control implementation. Varieties of control schemes have been proposed for these systems and major concerns such as passivity, stability and transparency have been studied. Recently, unreliable communication networks affected by packet loss and variable transmission delays have been received much attention. Thus, it is worth considering discrete-time theories for bilateral teleoperation architectures, which are formulated on the same lines as the continuous-time systems. Despite the extensive amount of researches concerning continuous-time teleoperation systems, only a few papers have been published on the analysis and controller design for discrete bilateral forms. This paper takes into account the challenges for the discrete structure of bilateral teleoperation systems and notifies the recent contributions in this area. The effect of sampling time on the stability-transparency trade-off and the task performance is taken into consideration in this review. These studies can help to design guidelines to have better transparency and stable teleoperation systems.

Relying solely on virtual springs and dampers, the transparency of standard virtual coupling suffers from the device-proxy coordination error when a large interaction force is engaged (e.g., contact tasks) and also from the unmodifiable inertias of the haptic device and the virtual proxy. To overcome these limitations, we propose a novel virtual coupling scheme, which, utilizing passive decomposition and a human force observer, can maintain the device-proxy coordination error even during contact tasks, while also allowing for scaling down (or up) the apparent inertia of the coordinated device-proxy system, thereby, substantially improving transparency of the standard virtual coupling. Experiments are performed to show the performance and passivity of the proposed virtual coupling. Minimum-possible passive inertia scaling is also theoretically established via some positive-real analysis.

Stability and transparency are two critical indices of bilateral teleoperation systems. The wave variable method is a conservative approach to robustly guarantee system passivity under arbitrary constant time delays. However, the wave-variable-based reflection is an intrinsic problem in this method because it can significantly degrade system transparency and disorient the operator's perception of the remote environment. In order to enhance both the transparency and the stability of bilateral teleoperation systems in the presence of large time delays, a new four-channel (4-CH) architecture is proposed which applies two modified wave-transformation controllers to reduce wave-based reflections. Transparency and stability of the proposed system are analyzed and the improvement in these when using this method is measured experimentally. Results clearly demonstrate that the proposed method can produce high transparency and stability even in the presence of large time delays.

This paper presents new proofs of four stability properties (semiglobal strict passivity, semiglobal asymptotic stability, semiglobal input-to-state stability, and semiglobal uniform ultimate boundedness with an arbitrarily reducible ultimate bound) of a rigid-link manipulator under proportional-integral-derivative (PID) position control. The proofs employ a strict Lyapunov function and a novel parameterization to provide four inequality conditions for the stability properties. In those inequalities, arithmetic operations on physical quantities are physically consistent if the joints are all revolute or all prismatic. A gain selection procedure is presented by which the ultimate bounds of velocity error, position error, and its integral can be independently designed.

This paper presents the research work on a 1 degree of freedom (DOF) force reflecting tele-micromanipulation system. This system enables a human operator to position remote objects very precisely having haptic feedback. The slave robot is a nano-positioning piezo-actuator with hysteretic dynamics. This intrinsic nonlinearity results in positioning inaccuracy and instability. Hence, a LuGre friction model is employed to model and compensate for this undesirable behavior. By means of a transformation, the 2-DOF master–slave system (1-DOF each) is decomposed into two 1-DOF new systems: the shape system, representing the master–slave position coordination, and the locked system, representing dynamics of the coordinated system. A key innovation of this paper is to generalize this approach to the hysteresis-type nonlinear teleoperated systems. For the shape system, a position tracking controller is designed in order to achieve position coordination. This position coordination is guaranteed not only in free space motion, but also during contact at the slave side. Furthermore, a force tracking controller is designed for the locked system in order to achieve tracking of the force exerted on the master and slave robots. Using this force controller, transparency is remarkably enhanced. Based on the virtual flywheels concept, passivity of the closed-loop teleoperator is guaranteed against dynamic parameter uncertainties and force measurement inaccuracies. The simulation and experimental results verify the capability of the proposed control architectures in achieving high-level tracking of the position and force signals while the system remains stable.

Part II continues to develop a hyper-stability framework for presenting physical interpretations of dexterous motion controls, such as hybrid position/force, impedance, model-based adaptive, learning control and coordination. In all cases passivity induced by introduction of a quasi-natural potential plays a key role. In view of these considerations, the final section discusses the possibility of development of a nonlinear circuit theory based on feedback connections of hyper-stable blocks, which may give rise to a physical understanding of dexterous and skilled motions for nonlinear mechanical systems and, eventually lead to the design of intelligent functions implementable in robotic machines.

The purpose of this paper is to show that the method of controlledLagrangians and its Hamiltonian counterpart (based on the notionof passivity) are equivalent under rather general hypotheses. Westudy the particular case of simple mechanical control systems(where the underlying Lagrangian is kinetic minus potentialenergy) subject to controls and external forces in some detail.The equivalence makes use of almost Poisson structures (Poissonbrackets that may fail to satisfy the Jacobi identity) on theHamiltonian side, which is the Hamiltonian counterpart of a classof gyroscopic forces on the Lagrangian side.

We report the case of a patient with unilateral left-sided auditory hallucinations in association with a left middle ear infection, who in addition demonstrated a symptom of passivity, attributing the infection to the actions of a voice. The case demonstrates the potential for complex interplay between physical and mental pathology.