Stability and Transparency Analysis of a Teleoperation Chain For Microscale Interaction.

International audienceMicroscale teleoperation with haptic feedback requires scaling gains in the order of 104 107. These high gains impose a trade-off between stability and transparency. Due to the conservative approach used in most designs, transparency is reduced since damping is added to the system to guarantee stability. Starting from the fact that series, negative feedback and parallel connection of passive systems is a passive system, a new approach is addressed in this work. We propose here a complete teleoperation chain designed from the ground up for full transparency and stability, including a novel self-sensing probe and a high fidelity force-feedback haptic interface. By guaranteeing the passivity of each device and assuming that the human operator and the environment are passive systems, a homothetic direct coupling can be used without jeopardizing the stability and provides best transparency. The system is experimentally demonstrated in the complex case of a probe interacting with a water droplet under human control, while accurately transcribing the interaction back to operator

A Review of Haptic Feedback Teleoperation Systems for Micromanipulation and Microassembly

International audienceThis paper presents a review of the major haptic feedback teleoperation systems for micromanipulation. During the last decade, the handling of micrometer-sized objects has become a critical issue. Fields of application from material science to electronics demonstrate an urgent need for intuitive and flexible manipulation systems able to deal with small-scale industrial projects and assembly tasks. Two main approaches have been considered: fully automated tasks and manual operation. The first one require fully pre determined tasks, while the later necessitates highly trained operators. To overcome these issues the use of haptic feedback teleoperation where the user manipulates the tool through a joystick whilst feeling a force feedback, appears to be a promising solution as it allows high intuitiveness and flexibility. Major advances have been achieved during this last decade, starting with systems that enable the operator to feel the substrate topology, to the current state-of-the-art where 3D haptic feedback is provided to aid manipulation tasks. This paper details the major achievements and the solutions that have been developed to propose 3D haptic feedback for tools that often lack 3D force measurements. The use of virtual reality to enhance the immersion is also addressed. The strategies developed provide haptic feedback teleoperation systems with a high degree of assistance and for a wide range of micromanipulation tools. Based on this expertise on haptic for micromanipulation and virtual reality assistance it is now possible to propose microassembly systems for objects as small as 1 to 10 micrometers. This is a mature field and will benefit small-scale industrial projects where precision and flexibility in microassembly are required

Symmetric impedance matched teleoperation with position tracking

金沢大学大学院自然科学研究科知能情報・数理In this paper, we propose a novel passivity-based teleoperation architecture for bilateral force and position tracking control problem. It has the passivity-based symmetric impedance matched architecture with a virtual damping. The novel teleoperation can solve the problems of position tracking. Lyapunov stability methods are used to establish the range of position control gains on the master and slave side. We show the asymptotical stability of the system. Then the controller is designed considering a trade-off between an operationability and a position tracking performance. Experimental results show the effectiveness of our proposed symmetric impedance matched teleoperation compared with the conventional one. ©2006 IEEE

a teleoperation system for micro invasive brain surgery

AbstractThis paper deals with controller design issues for a neurosurgical teleoperator system. The specific application of interest consists of remotely inserting a linear-stage rigid endoscope into the patient's brain for microinvasive neurosurgery interventions. This work aims at evaluating advantages and drawbacks of using a general-purpose control architecture versus a simpler task-oriented architecture, from a point of view of stability and transparency. Experiments revealed that in spite of its simplicity, the task-oriented design allows an improvement in the trade-off between performance, transparency and stability requirements

Analysis and Modeling of Human Impedance Properties for Designing a Human-Machine Control System

Abstract — A human can control dynamic properties of his/her own body naturally and effectively according to tasks by utilizing the perceived information of environmental character-istics. If dynamic properties of human movements depending on environmental characteristics can be described quantitatively, there would be expected to design and develop a novel human-machine system in which an operator can manipulate more comfortably. This paper discusses a design methodology of human-machine systems integrating human motor character-istics. A vehicle interface system manipulated by the foot is focused on, and mechanical impedance properties of human lower extremities during maintained leg posture are investigated according to the leg posture and the foot force. I

Learn and Transfer Knowledge of Preferred Assistance Strategies in Semi-autonomous Telemanipulation

Enabling robots to provide effective assistance yet still accommodating the operator's commands for telemanipulation of an object is very challenging because robot's assistive action is not always intuitive for human operators and human behaviors and preferences are sometimes ambiguous for the robot to interpret. Although various assistance approaches are being developed to improve the control quality from different optimization perspectives, the problem still remains in determining the appropriate approach that satisfies the fine motion constraints for the telemanipulation task and preference of the operator. To address these problems, we developed a novel preference-aware assistance knowledge learning approach. An assistance preference model learns what assistance is preferred by a human, and a stagewise model updating method ensures the learning stability while dealing with the ambiguity of human preference data. Such a preference-aware assistance knowledge enables a teleoperated robot hand to provide more active yet preferred assistance toward manipulation success. We also developed knowledge transfer methods to transfer the preference knowledge across different robot hand structures to avoid extensive robot-specific training. Experiments to telemanipulate a 3-finger hand and 2-finger hand, respectively, to use, move, and hand over a cup have been conducted. Results demonstrated that the methods enabled the robots to effectively learn the preference knowledge and allowed knowledge transfer between robots with less training effort

Multivariable Loop-Shaping in Bilateral Telemanipulation

Abstract This paper presents an architecture and control methodology for obtaining transparency and stability robustness in a multivariable bilateral teleoperator system. The work presented here extends a previously published single-input, single-output approach to accommodate multivariable systems. The extension entails the use of impedance control techniques, which are introduced to render linear the otherwise nonlinear dynamics of the master and slave manipulators, in addition to a diagonalization multivariable loop shaping technique, used to render tractable the multivariable compensator design. A multivariable measure of transparency is proposed based on the relative singular values of the environment and transmitted impedance matrices. The approach is experimentally demonstrated on a three degree-of-freedom scaled telemanipulator pair with a highly coupled environment. Using direct measurement of the power delivered to the operator to assess the system's stability robustness, along with the proposed measure of multivariable transparency, the loop-shaping compensation is shown to improve the stability robustness by a factor of two and the transparency by more than a factor of five. Fite and Goldfarb Multivariable Loop Shaping … 2 Introduction Bilateral teleoperation systems provide for human interaction with an environment while alleviating the necessity of direct contact between the two. Using a pair of robot manipulators, such a system enables dexterous human manipulation in remote, hazardous, or otherwise inaccessible environments. Bilateral telemanipulators can additionally incorporate power attenuation or amplification between the human operator and environment, allowing for human manipulation of microscopic objects (in the case of macro-micro bilateral telemanipulation) or large-scale objects (in the case of man-amplifiers). The teleoperative performance can be characterized by the transparency, which is a measure of the extent to which the telemanipulation system presents the undistorted dynamics of the environment to the human operator. A common goal in the control of bilateral telemanipulation is to provide transparent teleoperation while ensuring the robust stability of the human-telemanipulator-environment loop. Prior Work Several researchers have investigated aspects of transparency and stability in telemanipulation, primarily through the use of two-port network modeling techniques. Doyle [7], to assess the stability of a macro-micro bilateral telemanipulator interacting with a passive human operator and environment. Though the telemanipulator itself was a singledegree-of-freedom system, the human-teleoperator-environment interaction was formulated in a manner that required multivariable tools in order to assess stability robustness. Colgate did not explicitly treat transparency, but instead utilized impedance shaping to intentionally alter the dynamics as perceived by the human operator through the telemanipulator. Itoh et al. experimentally implemented a six degree-of-freedom telemanipulator using passivity theory to address stability robustness, but instead of providing transparency, the telemanipulator was controlled to exhibit a task-oriented dynamic behavior specified in order to facilitate a particular telemanipulation task. Hashstrudi-Zaad and Salcudean theoretically assessed the performance and stability robustness of a three degree-of-freedom telemanipulator by incorporating a parallel force/position control to linearize and decouple the manipulators, and by assuming the human operator and environment to be decoupled, in which case the analysis reduces to that required for three decoupled single-degree-of-freedom systems. In contrast to the combined hybrid parameter/passivity based approach, the architecture proposed by Fite et al. [8] formulates the teleoperation system as a single feedback loop to which the tools of classical control theory can then be applied to address the performance and stability robustness. In so doing, the stability robustness of the system is addressed in a non-conservative manner, and the transparency is addressed only in the bandwidth of interest. This loop shaping approach was developed in a single input, single output context; since telemanipulation Fite and Goldfarb Multivariable Loop Shaping … 4 applications generally involve systems with coupled multiple degrees of freedom, however, such a method is of limited utility without extension to the multivariable case. As such, the work presented in this paper extends this previously published approach to the multivariable case of telemanipulation. Specifically, the extension entails the use of impedance control techniques to render linear the otherwise nonlinear dynamics of the master and slave manipulators, and employs a diagonalization multivariable loop shaping technique used to render tractable the multivariable loop shaping compensator design. A multivariable measure of transparency is additionally proposed based on the relative singular values of the environment and transmitted impedance matrices. 3 Multivariable Telemanipulation Architecture Fite and Goldfarb Multivariable Loop Shaping … 6 Given the master/human and slave/environment dynamics as previously described, the loop shaping telemanipulation architecture is obtained by combining the master/human and slave/environment subsystems with the position and force scaling matrices, C 1 and C 2 , respectively, as shown in The transparency of the multivariable teleoperation loop is determined by the relative distortion between the transmitted impedance (i.e., the impedance felt by the human operator) and the actual environment impedance. The impedance transmitted to the human operator by the telemanipulation system is given by: For perfect transparency, the transmitted impedance transfer function matrix of Eq. (3) should equal the actual environment impedance, Z e . In practice, these matrices need only be similar within some frequency band of interest. Thus, within this band of interest, perfect transparency requires the singular values of the transmitted impedance transfer function matrix to equal those of the actual environment impedance transfer function matrix. As such, a measure of the desired multivariable performance can be given by the ratio of the respective singular values of the impedance transmitted to the human operator to those of the environment impedance: where n rank = ) ( e t Z , Z and i δ represents distortion in the teleoperative system. A desired bandwidth of transparency can be prescribed by ensuring that the distortion i δ in each singular Fite and Goldfarb Multivariable Loop Shaping … 7 value is less than some allowable amount of distortion ∆ for a desired bandwidth of operation. For ∆= 3 dB, a prescription for good teleoperative performance can be written as: where t Ω is a desired bandwidth of teleoperative transparency. The overall objective of the control architecture is to achieve the desired performance specified by Eq. (5) while ensuring the robust stability of the closed-loop system. With the introduction of a loop shaping compensator in the motion communication channel, th

Transparent and Shaped Stiffness Reflection for Telesurgery

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Vehicle Active Steering Control System Based on Human Mechanical Impedance Properties of the Arms

This paper presents the experimental data of human mechanical impedance properties (HMIPs) of the arms measured in steering operations according to the angle of a steering wheel (limbs posture) and the steering torque (muscle cocontraction). The HMIP data show that human stiffness/viscosity has the minimum/maximum value at the neutral angle of the steering wheel in relax (standard condition) and increases/decreases for the amplitude of the steering angle and the torque, and that the stability of the arms\u27 motion in handling the steering wheel becomes high around the standard condition. Next, a novel methodology for designing an adaptive steering control system based on the HMIPs of the arms is proposed, and the effectiveness was then demonstrated via a set of double-lane-change tests, with several subjects using the originally developed stationary driving simulator and the 4-DOF driving simulator with a movable cockpit

Force-detecting gripper and force feedback system for neurosurgery applications

Purpose For the application of less invasive robotic neurosurgery to the resection of deep-seated tumors, a prototype system of a force-detecting gripper with a flexible micromanipulator and force feedback to the operating unit will be developed. Methods Gripping force applied on the gripper is detected by strain gauges attached to the gripper clip. The signal is transmitted to the amplifier by wires running through the inner tube of the manipulator. Proportional force is applied on the finger lever of the operating unit by the surgeon using a bilateral control program. A pulling force experienced by the gripper is also detected at the gripper clip. The signal for the pulling force is transmitted in a manner identical to that mentioned previously, and the proportional torque is applied on the touching roller of the finger lever of the operating unit. The surgeon can feel the gripping force as the resistance of the operating force of the finger and can feel the pulling force as the friction at the finger surface. Results A basic operation test showed that both the gripping force and pulling force were clearly detected in the gripping of soft material and that the operator could feel the gripping force and pulling force at the finger lever of the operating unit. Conclusions A prototype of the force feedback in the microgripping manipulator system has been developed. The system will be useful for removing deep-seated brain tumors in future master-slave-type robotic neurosurgery. © 2013 CARS