Bilateral control of teleoperators with time delay
TL;DR: In this paper, a control law for teleoperators is presented which overcomes the instability caused by time delay by using passivity and scattering theory, a criterion is developed which shows why existing bilateral control systems are unstable for certain environments, and why the proposed bilateral control law is stable for any environment and any time delay.
Abstract: A control law for teleoperators is presented which overcomes the instability caused by time delay. By using passivity and scattering theory, a criterion is developed which shows why existing bilateral control systems are unstable for certain environments, and why the proposed bilateral control law is stable for any environment and any time delay. The control law has been implemented on a single-axis force-reflecting hand controller, and preliminary results are shown. To keep the presentation clear, a single-degree-of-freedom (DOF) linear time-invariant (LTI) teleoperator system is discussed. Nevertheless, results can be extended, without loss of generality, to an n-DOF nonlinear teleoperation system. >
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01 Oct 1993
TL;DR: It is shown that a proper use of an four channels is of critical importance in achieving high performance telepresence in the sense of accurate transmission of task impedances to the operator.
Abstract: Tools for quantifying teleoperation system performance and stability when communication delays are present are provided A general multivariable system architecture is utilized which includes all four-types of data transmission between master and slave: force and velocity in both directions It is shown that a proper use of an four channels is of critical importance in achieving high performance telepresence in the sense of accurate transmission of task impedances to the operator It is also shown that transparency and robust stability (passivity) are conflicting design goals in teleoperation systems The analysis is illustrated by comparing transparency and stability in two common architectures, as well as a recent passivated approach and a new transparency-optimized architecture, using simplified one-degree-of-freedom examples >
2,083 citations
TL;DR: This survey addresses the subject of bilateral teleoperation, a research stream with more than 50 years of history and one that continues to be a fertile ground for theoretical exploration and many applications.
1,584 citations
12 May 1992
TL;DR: New control schemes of master-slave manipulators are proposed that provide the ideal kinesthetic coupling such that the operator can maneuver the system as though he/she were directly manipulating the remote object himself/herself.
Abstract: In this paper, the analysis and design of master-slave teleoperation systems are discussed. The goal of this paper is to build a superior master-slave system that can provide good maneuverability. We first analyze a one degree-of-freedom system including operator and object dynamics. Second, some ideal responses of master-slave systems are defined and a quantitative index of maneuverability is given, based on the concept of ideal responses. Third, we propose new control schemes of master-slave manipulators that provide the ideal kinesthetic coupling such that the operator can maneuver the system as though he/she were directly manipulating the remote object himself/herself. The proposed control scheme requires accurate dynamic models of the master and slave arms, but neither parameters of the remote object nor the operator dynamics is necessary. Finally, the proposed control scheme is introduced to a prototype master-slave system and the experimental results show the validity of the proposed scheme. >
953 citations
01 Jan 2003
TL;DR: Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science Electrical Engineering The University of New Mexico Albuquerque, New Mexico August, 2003 Stability Analysis of Networked Control Systems by Peter F.S.
Abstract: OF THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science Electrical Engineering The University of New Mexico Albuquerque, New Mexico August, 2003 Stability Analysis of Networked Control Systems by Peter F. Al-Hokayem B.E. Computer and Communications Engineering, American University of Beirut, Lebanon, July 2001 M.S. Electrical Engineering, University of New Mexico, 2003
837 citations
Patent•
18 Nov 1999TL;DR: In this article, a region of the heart is stabilized by engaging a stabilizer without having to stop the heart, and the stabilizer is coupled to a drive system to position the surface from outside the patient, preferably by actuators of the robotic servomechanism.
Abstract: Surgical methods and devices allow closed-chest surgery to be performed on a heart of a patient while the heart is beating. A region of the heart is stabilized by engaging a surface of the heart with a stabilizer without having to stop the heart. Motion of the target tissues is inhibited sufficiently to treat the target tissues with robotic surgical tools which move in response to inputs of a robotic system operator. A stabilizing surface of the stabilizer is coupled to a drive system to position the surface from outside the patient, preferably by actuators of the robotic servomechanism. Exemplary stabilizers includes a suture or other flexible tension member spanning between a pair of jointed bodies, allowing the member to occlude a coronary blood vessel and/or help stabilize the target region between the stabilizing surfaces.
642 citations
References
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01 Feb 1987
TL;DR: A framework for the analysis and control of manipulator systems with respect to the dynamic behavior of their end-effectors is developed, and the unified approach for motion and force control is developed.
Abstract: A framework for the analysis and control of manipulator systems with respect to the dynamic behavior of their end-effectors is developed. First, issues related to the description of end-effector tasks that involve constrained motion and active force control are discussed. The fundamentals of the operational space formulation are then presented, and the unified approach for motion and force control is developed. The extension of this formulation to redundant manipulator systems is also presented, constructing the end-effector equations of motion and describing their behavior with respect to joint forces. These results are used in the development of a new and systematic approach for dealing with the problems arising at kinematic singularities. At a singular configuration, the manipulator is treated as a mechanism that is redundant with respect to the motion of the end-effector in the subspace of operational space orthogonal to the singular direction.
2,849 citations
01 Jan 1987
TL;DR: The authors present a foundation for force control strategies, in view of the fact that the type of control strategy that is employed depends fundamentally on the characteristics of the environment, and introduce a general control approach, called hybrid impedance control.
Abstract: The inclusion of force information in the control of robots increases their adaptability to uncertain environments, such as are found in deburring, grinding, and assembly tasks. The authors present a foundation for force control strategies, in view of the fact that the type of control strategy that is employed depends fundamentally on the characteristics of the environment. A general control approach is introduced, called hybrid impedance control which in its simplest forms reduces the operational space control of O. Khatib and J. Burdick (1986), or to N. Hogan's (1985) impedance control. The control law is formulated in a general enough fashion, however, to allow for higher order controllers. >
394 citations
TL;DR: Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1964.
Abstract: Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1964.
342 citations
TL;DR: Experimental results suggest that alternative displays of the feedback force can overcome the stability problem of long delays coupled with high loop gain in master-slave manipulators.
Abstract: In master-slave manipulators, forces encountered by the remote hand are transmitted back to the operator. At very great distances there will be a transmission delay between an operator's movement and a resulting force. Investigation was made of the effect of long delays and differences in strategy on positioning time with force feedback alone. Positioning could be accomplished, but delay coupled with high loop gain creates serious instability. Experimental results suggest that alternative displays of the feedback force can overcome the stability problem.
268 citations
24 Apr 1988
TL;DR: It is shown that human operator properties, which vary as a result of different types of grasp of the handle, affect the stability of the system in the hard-contact task, and human operator biomechanics must be taken into account to guarantee stable and ergonomic performance of advanced teleoperators.
Abstract: Experiments and simulations of a single-axis force-reflecting teleoperation system have been conducted to investigate the problem of contacting a hard environment and maintaining a controlled force in teleoperation in which position is fed forward from the hand controller (master) to the manipulator (slave), and force is fed back to the human operator through motors in the master. The simulations, using an electrical circuit model, reproduce the behavior of the real system, including effects of human operator biomechanics. It is shown that human operator properties, which vary as a result of different types of grasp of the handle, affect the stability of the system in the hard-contact task. The effect of a heavier grasp on the handle is equivalent to increased hand-controlled velocity damping in terms of the systems stability in the contact task, but control system damping sufficient to guarantee stable contact results in perceptible sluggishness of the control handle's response in free motion. These results suggest that human operator biomechanics must be taken into account to guarantee stable and ergonomic performance of advanced teleoperators. >
209 citations