Bilateral Control Architecture Research Articles

Design and Development of a Dexterous Bilateral Robotic Microinjection System Based on Haptic Feedback

In this paper, a dexterous bilateral robotic system with haptic feedback is designed and developed for microinjection of biological samples. For the first time, the robotic system has been developed for microinjection of both zebrafish larvae and embryos. The master device is constructed by a seven-degree-of-freedom (7-DOF) haptic interface. As the slave device, a 6-DOF microinjection robot is developed by integrating a 3-DOF micropositioning stage and a 3-DOF micromanipulator. One uniqueness of the proposed robotic system is that the injection targets can be placed directly in the Petri dish without prior pose adjustment. The master haptic device not only enables remote control of the microinjection robot by a human operator, but also provides an intuitive haptics feedback to the operator for executing the microinjection operation with a high success rate. The haptic interface is deployed as a viscous damping to enhance the smoothness and stability of its movement. Moreover, a hybrid bilateral control architecture is developed for the system to achieve ideal performance of position tracking and haptic telepresence. A prototype system is developed for performance test. The experimental results of individual and continuous microinjection of zebrafish larvae demonstrate fine position/force tracking capability and flexibility. Note to Practitioners—Microinjection is a universal operation in biological study for delivering foreign materials into biological samples. The existing manual and automated microinjections have limited flexibility. Meanwhile, the stand-alone visual information cannot provide enough telepresence to the operator, which results in low success rate and poor repeatability. This paper proposes a new haptics-based dexterous bilateral robotic system dedicated to microinjection task of both zebrafish larvae and embryos. Both the master haptic interface and slave microinjection robot exhibit multi-DOF motion, which enables a dexterous micromanipulation with high success rate for the human operator. The feasibility of the reported robotic system has been verified by performing microinjection operation of different targets.

Bilateral teleoperation with continuously variable scaling and PD force control

This paper investigates the bilateral teleoperation with the possibility of continuously variable scaling during real-time operation. The algorithm proposed for this purpose provides the operator with the ability to change the scaling gains of force and velocity loops during operation. The controllers are derived to enforce exponentially decaying error dynamics on systems which have inner loop disturbance compensation. The proposed architecture assumes the scale factors as continuous functions of time which have continuous derivatives that are also included in the mathematical derivation. Unlike the existing studies, the presented framework allows real-time adaptation of scaling gains, which provides the user with the ability to conduct coarse and fine motion in the same operation. The Lyapunov stability proof of the proposed method is made and the margins of the controller gains are identified for practical operation. Furthermore, the operational accuracy is enhanced by the application of a PD force control loop which is also new for scaled bilateral teleoperation. The realization of PD loop is made using an [Formula: see text]-[Formula: see text]-[Formula: see text] filter to differentiate the force signal. The algorithm is validated on a setup consisted of two single DOF motion control systems. In order to provide a complete analysis, a wide range of experiments are made, velocity and force scales having sinusoidal patterns with different amplitudes and frequencies. Moreover, comparison with a classical bilateral control architecture is made to highlight the flexibility of the proposed control method. The efficacy of the proposed approach is solidified by the successful tracking responses obtained from these experiments.

A New Control Architecture for Stable and Transparent Haptic Feedback of Interactive Simulation

This paper proposes a new control architecture for stable and transparent haptic rendering of interactive simulation involving a rigid tool and deformable objects. The traditional direct and proxy-based haptic rendering schemes are analyzed for the absolute stability, and transmit impedance employing the well-known bilateral control architecture frequently used in the field of teleoperation systems. An equivalent impedance is conveyed in the proposed control scheme to the haptic device instead of the contact force between the virtual tool and the object. The trade-off problem between the absolute stability and the transmitted impedance is resolved by computing the haptic feedback using the equivalent impedance. The proposed rendering scheme shows higher transparency than the conventional haptic rendering methods while maintaining the absolute stability.

An Energy Tank-Based Interactive Control Architecture for Autonomous and Teleoperated Robotic Surgery

Introducing some form of autonomy in robotic surgery is being considered by the medical community to better exploit the potential of robots in the operating room. However, significant technological steps have to occur before even the smallest autonomous task is ready to be presented to the regulatory authorities. In this paper, we address the initial steps of this process, in particular the development of control concepts satisfying the basic safety requirements of robotic surgery, i.e., providing the robot with the necessary dexterity and a stable and smooth behavior of the surgical tool. Two specific situations are considered: the automatic adaptation to changing tissue stiffness and the transition from autonomous to teleoperated mode. These situations replicate real-life cases when the surgeon adapts the stiffness of her/his arm to penetrate tissues of different consistency and when, due to an unexpected event, the surgeon has to take over the control of the surgical robot. To address the first case, we propose a passivity-based interactive control architecture that allows us to implement stable time-varying interactive behaviors. For the second case, we present a two-layered bilateral control architecture that ensures a stable behavior during the transition between autonomy and teleoperation and, after the switch, limits the effect of initial mismatch between master and slave poses. The proposed solutions are validated in the realistic surgical scenario developed within the EU-funded I-SUR project, using a surgical robot prototype specifically designed for the autonomous execution of surgical tasks like the insertion of needles into the human body.

Transparent four-channel bilateral control architecture using modified wave variable controllers under time delays

SUMMARYStability 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.

A powered prosthetic intervention for bilateral transfemoral amputees.

This paper presents the design and validation of a control system for a pair of powered knee and ankle prostheses to be used as a prosthetic intervention for bilateral transfemoral amputees. The control system leverages communication between the prostheses for enhanced awareness and stability, along with power generation at the knee and ankle joints to better restore biomechanical functionality in level ground walking. The control methodology employed is a combination of an impedance-based framework for weight-bearing portions of gait and a trajectory-based approach for the nonweight-bearing portions. The control system was implemented on a pair of self-contained powered knee and ankle prostheses, and the ability of the prostheses and control approach to provide walking functionality was assessed in a set of experimental trials with a bilateral transfemoral amputee subject. Specifically, experimental data from these trials indicate that the powered prostheses and bilateral control architecture provide gait kinematics that reproduce healthy gait kinematics to a greater extent than the subject's daily-use passive prostheses.

Fuzzy PID Control Method for Internet-based Tele-operation Manipulators System

Trajectory tracking control problem for internet-based tele-operation system is researched in this paper. The control structure of master and slave tele-operation manipulators adapts bilateral servo control architecture with force deviation feedback. The simulation model of three degrees of freedom (3-DOF) manipulator is presented. In order to ensure the synchronization of positions of the master and slave manipulators, a fuzzy PID control method is proposed. This control algorithm is to adjust the three parameters of PID controller online by fuzzy control method. The contrast simulation experiments of PID and fuzzy PID control methods show that the proposed control method can effectively improve the force and position tracking performance and reduce time delay. DOI: http://dx.doi.org/10.11591/telkomnika.v11i11.2923 Full Text: PDF

Telepresence Index for Bilateral Teleoperations

This paper proposes a performance index called telepresence index for bilateral teleoperation, which can be used both for the performance evaluation of bilateral control architectures and for design purposes. This index is intended to represent a comprehensive performance objective consisting of transparency and kinematic correspondence, which are two major performance objectives of bilateral teleoperation. In order to quantify the performance objective, telepresence index has employed the error vector magnitude, which enables a seamless combination of magnitude and phase errors and the accommodation of time delay. In comparison with existing performance indices, it was observed that telepresence index possesses the comprehensiveness of performance objectives, magnitude/phase integrity, and the capacity to include time delay, which the others lack in one way or another. The index was applied to evaluate the performances of two widely known control architectures: PD-type bilateral control and Ueda's ideal control. In all cases, telepresence index has been compared favorably with the other indices in terms of clarity, convenience, and accuracy, thereby demonstrating its superiority.

An analysis of static output feedback control for tendon driven master-slave manipulator — Simulation study

In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the power transmission tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. The system model is reduced to guarantee the controllability and observability which are necessity for the static output feedback control by using modal analysis. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.

Application of Two-Port Network in Bilateral Control for a Haptic Interface with Force-Position Compensation

The two-port network theory for describing the characteristics of the haptic interface is presented; the four-channel bilateral control architecture is introduced, and two control methods named position-error-based control and direct force reflection control (PEBC & DFRC) are also presented. Two main problems caused by the coupling between position and force information for transparency improvement of the haptic interface are also be discussed and a Model-Based Force-Position Compensation Strategy to enhance the transparency of the haptic interface is proposed. By embedding the compensation unit into the DFRC architecture, the Haptic Interface could be controlled with precise position and high-fidelity force feedback.

Effect of Scaling on the Performance and Stability of Teleoperation Systems Interacting with Soft Environments

There is generally a tradeoff between stability and performance in haptic control systems. Teleoperation systems with haptic feedback are no exception. Scaling in these systems used in applications such as telemicrosurgical systems has further effects on the stability and performance. This paper focuses on those applications interacting with soft tissues and analyzes the effects of the scaling in an effort to increase the performance of these systems while maintaining the stability. Position tracking and kinesthetic perception are especially important in the tele-surgical systems and, hence, are used as the performance criteria. Quantitatively defined stability robustness, which is based on Llewellyn's absolute stability criterion, is used as a metric for stability analysis. Various choices of scaling factors, and human and environment impedances are then investigated. The proposed kinesthetic perception concept is validated using psychophysical experiments. Widely used bilateral control architectures such as the two-channel position–position, two-channel force–position and four-channel controls are specifically analyzed and evaluated using simulations and experiments with phantom soft tissues. Results also show that the force–position control architecture shows the best position tracking performance irrespective of the scaling factors while the four-channel controller shows the best kinesthetic perception capability.

An Approach to Force-Sensorless Bilateral Control in Master-Slave System with Different Configurations

In this paper, force-sensorless bilateral control methods for a master-slave system with different configurations are proposed. Two types of bilateral control architectures are presented. One is based on joint space control, and the other is based on work space control. This paper discusses the difference between these control methods from the viewpoint of motion behavior in the singular configuration. Finally, actual experimental results that confirm the validity of the proposed methods are shown.

원격지 현장감을 향상시키기 위한 무인차량 원격조종에 관한 연구

In this paper, we proposed a teleoperation scheme of unmanned grounded vehicle to improve telepresence. Especially, bilateral control architecture for transmitting realistic steering feeling to the remote driver is investigated. System architecture of the teleoperated remote vehicle is introduced with visual, auditory and kinesthetic haptic channel. Several bilateral control architectures are proposed for transmitting remote steering feeling, and subject tests are done to evaluate the performance. Position-force bilateral control architecture with returning torque compensation algorithm shows best performance.

Bounded-Impedance Absolute Stability of Bilateral Teleoperation Control Systems.

Available passivity-based robust stability methods for bilateral teleoperation control systems are generally conservative, as they consider an unbounded range of dynamics for the class of passive operators and environments in the complex plane. In this paper, we introduce a powerful 3D geometrical robust stability analysis method based on the notions of wave variables and scattering parameters. The methodology, which was originally a 2D graphical method used in microwave systems for single-frequency analysis [1], is further developed in this paper for teleoperation and haptic systems. The proposed method provides both mathematical and visual aids to determine bounds or regions on the complex frequency response of the passive environment impedance parameters for which a potentially unstable system connected to any passive operator is stable, and vice-versa. Furthermore, the method allows for the design of bilateral controllers when such bounds are known, or can even be utilized when the environment dynamics are active. The geometrical test can also be replaced by an equivalent mathematical condition, which can easily be checked via a new stability parameter. The proposed method results in less conservative guaranteed stability conditions compared to the Llewellyn's criterion; thus, promising a better compromise between stability and performance. The new method is numerically evaluated for two bilateral control architectures.

텐던 구동 마스터-슬레이브 조작기 최적 정적 출력 되먹임 제어

In this work, a bilateral control for a master-slave manipulator system which will be used for handling objects contaminated by radioactivity has been addressed. The links of manipulators are driven independently by individual motors installed on the base and the driving torque is transmitted through pre-tensioned tendons. The measurable variables are the positions and rates of master/slave motors. In the consideration of the flexibility of the tendon and available measurements for control, we proposed an optimal static output feedback control for possible bilateral control architecture. By using modal analysis, the system model is reduced to guarantee the detectability which is a necessity for the static output feedback control design. Based on the reduced model, the control gains are determined to attenuate vibration in the sense of optimality. The feasibility of the proposed control design was verified along with some simulation results.

Stability and performance in delayed bilateral teleoperation: Theory and experiments

In the presence of communication latency in a bilaterally controlled teleoperation system, stability and transparency are severely affected. In this paper, based on a passivity framework, admittance-type and hybrid-type delay-compensated communication channels, which warrant different bilateral control architectures, are introduced. Wave transforms and signal filtering are used to make the delayed-communication channel passive and passivity/stability conditions are derived based on the end-to-end model of the teleoperation system with and without incorporating force measurement data of the master and the slave manipulators’ interactions with the operator and the remote environment in the control configuration. Based on analogies of the hybrid parameters of the teleoperation systems, it is demonstrated that using force sensor measurements about hand/master and/or slave/environment interactions in the control algorithm can significantly improve teleoperation transparency. Experimental results with a soft-tissue task for a hybrid-type architecture and for round-trip delays of 60 and 600 ms further substantiate the hypothesis that using slave-side force measurements considerably enhances the matching of the master and the slave forces and consequently the transparency compared to a position error-based configuration.

Transparent Bilateral Control Architecture by State Convergence for Telerobotics

This paper presents a bilateral control scheme designed to achieve the two main goals of a teleoperation system: stability and transparency. The control scheme allows that the slave follows the master, ant that the force displayed to the operator was exactly the reaction force from the environment. In addition, the interaction force of the slave with the environment is adapted to the master/slave ratio when it is reflected to the operator, improving the transparency of the system. The bilateral control scheme can be used in contact situations or non-contact situations (free motion) of the slave with the environment. Together with the control scheme, the paper describes an analytical design method that allows to obtain the control gains.

High-Fidelity Bilateral Teleoperation Systems and the Effect of Multimodal Haptics

In master-slave teleoperation applications that deal with a delicate and sensitive environment, it is important to provide haptic feedback of slave/environment interactions to the user's hand as it improves task performance and teleoperation transparency (fidelity), which is the extent of telepresence of the remote environment available to the user through the master-slave system. For haptic teleoperation, in addition to a haptics-capable master interface, often one or more force sensors are also used, which warrant new bilateral control architectures while increasing the cost and the complexity of the teleoperation system. In this paper, we investigate the added benefits of using force sensors that measure hand/master and slave/environment interactions and of utilizing local feedback loops on the teleoperation transparency. We compare the two-channel and the four-channel bilateral control systems in terms of stability and transparency, and study the stability and performance robustness of the four-channel method against nonidealities that arise during bilateral control implementation, which include master-slave communication latency and changes in the environment dynamics. The next issue addressed in the paper deals with the case where the master interface is not haptics capable, but the slave is equipped with a force sensor. In the context of robotics-assisted soft-tissue surgical applications, we explore through human factors experiments whether slave/environment force measurements can be of any help with regard to improving task performance. The last problem we study is whether slave/environment force information, with and without haptic capability in the master interface, can help improve outcomes under degraded visual conditions.