Slave Robot Research Articles

Pneumatically driven surgical forceps displaying a magnified grasping torque.

Background: Sensing the grasping force and displaying the force for the operator are important for safe operation in robot‐assisted surgery. Although robotic forceps that senses the force by force sensors or driving torque of electric motors is proposed, the force sensors and the motors have some problems such as increase in weight and difficulty of the sterilization. Method: We developed a pneumatically driven robotic forceps that estimates the grasping torque and display the magnified torque for the operator. The robotic forceps has a master device and a slave robot, and they are integrated. In the slave side, the grasping torque is estimated by the pressure change in the pneumatic cylinder. A pneumatic bellows display the torque through a linkage. Results: We confirmed that the slave robot follows the motion of the master, and the grasping torque is estimated in the accuracy of 7 mNm and is magnified and displayed for the operator. Conclusions: The pneumatically driven robotic forceps has the capability in the estimation of the grasping torque and display of the torque. Regarding future work, the usability and fatigues of the surgeons must be evaluated.

Single Master Bimanual Teleoperation System With Efficient Regulation

This article proposes a new single master bimanual teleoperation system with an efficient position, orientation, and force regulation strategy. Unlike many existing studies that solely support motion synchronization, the first contribution of the proposed work is to propose a solution for orientation regulation when several slave robots have differing motions. In other words, we propose a solution for self-regulated orientation for dual-arm robots. A second contribution in the article allows the master with fewer degrees of freedom (DoF) to control the slaves (with higher DoF), while the orientation of the slaves is self-regulated. The system further offers a novel force regulation that enables the slave robots to have a smooth and balanced robot-environment interaction with proper force directions. Finally, the proposed approach provides adequate force feedback about the environment to the operator and assists the operator in identifying different motion situations of the slaves. Our approach demonstrates that the forces from the slaves will not interrupt the operator's perception of the environment. To validate the proposed system, experiments are conducted using a platform consisting of two 7-DoF slave robots and one 3-DoF master haptic device. The experiments demonstrated good results in terms of position, orientation, and force regulation.

Haptic Tele-Driving of Wheeled Mobile Robots Under Nonideal Wheel Rolling, Kinematic Control and Communication Time Delay

The increasing application of wheeled mobile robots (WMR) in many fields has brought new challenges on its control and teleoperation, two of which are induced by contact slippage phenomenon between wheel and terrain as well as time delays in the master-slave communication channel. In the WMR bilateral tele-driving system, in this paper, the linear velocity of the slave mobile robot follows the position command from the haptic master robot while the slippage-induced velocity error is fed back as a haptic force felt by the human operator. To cope with the slippage-induced nonpassivity and constant time delays, this paper proposes three methods to design the WMR bilateral teleoperation system’s controller. An experiment system is set up with Phantom Premium 1.5A haptic device as the master robot and a simulation platform of WMR as the slave robot. Experiments with the proposed methods demonstrate that they can result in a stable WMR bilateral tele-driving system under wheel’s slippage and constant time-delays.

Bilateral Control of Elbow and Shoulder Joints Using Functional Electrical Stimulation Between Humans and Robots

Robotic remote-control technologies have a wide field of applications. Bilateral control is a type of remote-control technique. Most of the existing bilateral control techniques require complicated force transmission mechanisms in the master systems. Therefore, operators feel discomfort due to a sense of restraint by the exoskeleton-type robot arms. We attempted to solve this problem by incorporating functional electrical stimulation into the master system. In this study, bilateral control was proposed between a human and a three-joint robot with three degrees of freedom using functional electrical stimulation for shoulder and elbow joints. The experiment consisted of extracting a block of Jenga using the slave robot. The proposed method was compared to unilateral control in which the master moves freely without feedback to the master.

A Novel Multilateral Control Design for Delayed Nonlinear Teleoperation System With RBFNN-based Environments

Abstract In this paper, a novel multilateral control design for nonlinear teleoperation system is proposed to improve the capability of multiple robots to coordinate efficiently and precisely in the remote environments under time-varying delays and various uncertainties. The environment is modeled with a general form of force under radial basis function neural network(RBFNN)-based identification and reconstruction to avoid the passivity issue in the traditional teleoperation control and provide the human operators with good sensing of environments. The desired trajectory producers and RBFNN-based sliding mode controllers are designed separately to achieve the good tracking of master/slave robots, and the coordinated distribution algorithm is designed to obtain the control input uS,i for each slave robot. Therefore, the global stability, good transparency performance with both position tracking and force feedback, and good cooperative performance can be achieved simultaneously for delayed nonlinear teleoperation system. The real platform experiment is carried out on a 2-master-2-slave teleoperation system to verify the effectiveness of proposed control design.

Experimental Results for Haptic Interaction With Virtual Holonomic and Nonholonomic Constraints

Force-feedback rendering of virtual tools in contact with virtual surfaces is an open research problem. A common strategy is to define an integrable implicit equation that represents the surface and to use the penalty method to haptically render the corresponding force. Nevertheless, some surfaces cannot be described this way, e. g., soft tissues, thus making real-time force rendering inaccurate. In this work, we propose a bilateral teleoperation scheme where the interaction between a virtual tool and a surface is represented by a virtual slave robot subject to holonomic and nonholonomic constraints. This approach allows to define a position-force controller that, on the one hand, guarantees position tracking between the virtual tool and the robot end-effector by projecting the operator's movements on a computer screen via the simulated robotic dynamic model, while on the other hand the felt reaction force is rendered by considering the forces generated by the master robot as references for the control system. To the best of the authors' knowledge this is the first time that nonholonomic constraints have been used to reproduce haptically deformable surfaces in a virtual reality system. Since such tactile sensations are subjective, a set of experiments are carried out to validate the proposed approach by comparing the force responses when using holonomic and nonholonomic constraints. Special emphasis is made on describing how both representations can be used to reproduce some tactile phenomena presented in medical training simulators.

Unifying bilateral teleoperation and tele-impedance for enhanced user experience

Usability is one of the most important aspects of teleoperation. Ideally, the operator’s experience should be one of complete command over the remote environment, but also be as close as possible to what they would have if physically present at the remote end, i.e., transparency in terms of both action and perception. These two aspects may coincide in favorable conditions, where classic approaches such as the four-channel architecture ensures transparency of the control framework. In the presence of substantial delays between the user and the slave, however, the stability–performance trade-off inherent to bilateral teleoperation deteriorates not only transparency, but also command. An alternative, unilateral approach is given by tele-impedance, which controls the slave–environment interaction by measuring and remotely replicating the user’s limb endpoint position and impedance. Not including force feedback to the operator, tele-impedance is absolutely robust to delays, whereas it completely lacks transparency. This article introduces a novel control framework that integrates a new, fully transparent, two-channel bilateral architecture with the tele-impedance paradigm. The result is a unified solution that mitigates problems of classical approaches, and provides the user with additional tools to modulate the slave robot’s physical interaction behavior, resulting in a better operator experience in spite of time inconsistencies. The validity and effectiveness of the proposed solution is demonstrated in terms of performance in the interaction tasks, of user fatigue and overall experience.

Neuro-fuzzy control of bilateral teleoperation system using FPGA

This paper presents an adaptive neuro-fuzzy controller ANFIS (Adaptive Neuro-Fuzzy Inference System) for a bilateral teleoperation system based on FPGA (Field Programmable Gate Array). The proposed controller combines the learning capabilities of neural networks with the inference capabilities of fuzzy logic, to adapt with dynamic variations in master and slave robots and to guarantee good practical robustness against the disturbances, by adjusting neuro-fuzzy network output parameters in a short time, thanks to the computing power of FPGA and its high sampling frequency. The design methodology adopted to design the control algorithm aims to minimize the hardware resources used by the FPGA in order to optimize the execution and the design times, and this by using the Fixed-Point Tool and HDL Coder features of MATLAB-Simulink. The proposed controllers were experimentally validated on a teleoperation system comprising a pair of one degree of freedom. The experimental results clearly show that the proposed ANFIS control algorithm significantly outperformed the conventional control methods (PID).

Advantage of Steerable Catheter and Haptic Feedback for a 5-DOF Vascular Intervention Robot System

Vascular intervention involves inserting a catheter and guidewire into blood vessels to diagnose and treat a disease in an X-ray environment. In this conventional vascular intervention procedure, the doctor is exposed to considerable radiation. To reduce the exposure, we developed a master–slave robot system. A steerable catheter is employed to shorten the task-time and reduce the contact force applied to the vessel walls during catheter insertion. The steerable catheter helps to select a vascular branch; thus, the radiation exposure time for patients is reduced, and perforation in the patient’s vessel is prevented. Additionally, the robot system employs a haptic function to replicate the physician’s tactile sensing in vascular intervention. In this study, the effectiveness of the steering catheter and haptic function was demonstrated experimentally in comparison with a conventional catheter.

A microsurgical robot research platform for robot-assisted microsurgery research and training

PurposeOcular surgery, ear, nose and throat surgery and neurosurgery are typical types of microsurgery. A versatile training platform can assist microsurgical skills development and accelerate the uptake of robot-assisted microsurgery (RAMS). However, the currently available platforms are mainly designed for macro-scale minimally invasive surgery. There is a need to develop a dedicated microsurgical robot research platform for both research and clinical training.MethodsA microsurgical robot research platform (MRRP) is introduced in this paper. The hardware system includes a slave robot with bimanual manipulators, two master controllers and a vision system. It is flexible to support multiple microsurgical tools. The software architecture is developed based on the robot operating system, which is extensible at high-level control. The selection of master–slave mapping strategy was explored, while comparisons were made between different interfaces.ResultsExperimental verification was conducted based on two microsurgical tasks for training evaluation, i.e. trajectory following and targeting. User study results indicated that the proposed hybrid interface is more effective than the traditional approach in terms of frequency of clutching, task completion time and ease of control.ConclusionResults indicated that the MRRP can be utilized for microsurgical skills training, since motion kinematic data and vision data can provide objective means of verification and scoring. The proposed system can further be used for verifying high-level control algorithms and task automation for RAMS research.

Design of Multi Robots Based on Single Master Commands

In any type of communication in robots one too many communication is only possible. I.e. One master node can communicate with one slave node only. But here we are going to build up to two slave robots that communicate with the master node. This is possible only by using signee as it is alone having a separate unique id for it. Here we have used only two slave robots for one master node but, we can add a number of robots for the master node having of different id’s using of ZigBee transfer protocol.

TURBot: A System for Robot-Assisted Transurethral Bladder Tumor Resection

Staging and treatment of nonmuscle-invasive bladder tumors using transurethral resection of bladder tumors (TURBT) is challenging due to limitations in intravesicular tool dexterity, visualization and risk of bladder wall perforation. Currently, TURBT is achieved via a rigid resectoscope. This dexterity limitation is exacerbated when tumors are located in the bladder neck region. To address these limitations, an endoscopic robotic system called TURBot was developed. The paper presents the design considerations, modeling, and control challenges that were addressed to enable the first robot-assisted in vivo TURBT. The design and control of a slave robot comprised of a multisegment continuum robot capable of deploying a micro snake-like continuum robot for control of an ablation laser, a grasper, and a fiberscope is presented. A strategy for constrained telemanipulation is presented based on the redundancy resolution with varying task dimension that is commensurate with the level of constraint experienced by the robot during transurethral deployment. In addition to evaluation in animals, TURBot resection is compared against manual resection in a mockup user study using a human bladder phantom. The contributions of this paper present key steps that pave the way toward successful clinical robot-assisted TURBT.

Semi-autonomous bilateral teleoperation of six-wheeled mobile robot on soft terrains

Abstract With the increasing use of multi-wheeled mobile robots in various fields, a few new challenges pertaining to the design of the teleoperation system of such robots have emerged. This paper proposes a new two-level architecture for haptic teleoperation of a six-wheeled mobile robot (SWMR) with a rocker-bogie chassis on soft terrains. In teleoperation, the linear and angular velocities of the SWMR base follow the master robot’s positions. At the slave SWMR level, local compensation controllers are designed for the driving motors and the steering motors to track the desired velocities of the base and eliminate the negative influence of wheel slippage. Command-tracking errors caused by wheel slippage at environment termination (ET) are conveyed to the human operator through haptic (force) feedback. By guaranteeing the passivity of ET, the stability conditions of the teleoperation system are constrained by the Llewellyn criterion. Experiments conducted using the proposed controllers demonstrated that the tracking errors in the commands sent to the slave robot are effectively compensated for, and the controllers achieve stable teleoperation with satisfactory tracking performance.

A multilateral impedance-controlled system for haptics-enabled surgical training and cooperation in beating-heart surgery

In this paper, an impedance-controlled multi-master/single-slave telerobotic system is developed for haptics-enabled surgical training and cooperation in beating-heart surgery. This system not only can enable automatically motion compensation for the beating heart’s motion as well as non-oscillatory force feedback to the human operators but can also enable training and cooperation for multiple users. A multi-user shared control architecture is developed, and a multilateral impedance-controlled strategy is employed for this architecture. The desired objectives of the proposed system are (a) providing position guidance to the trainees during training procedure, (b) providing force feedback to all human operators (trainer and trainees) regardless of their levels of authority over the slave robot, (c) motion compensation for the heart’s motion, and (d) reflecting only the non-oscillatory force portion of the slave-heart tissue interaction force to all human operators. To this end, virtual fixtures and a dominance factor are introduced, and a reference impedance model with adjusted parameters is designed for each master or slave robot. The proposed impedance-based control methodology is evaluated experimentally. The experimental results demonstrated that the proposed method could be used for surgical training and cooperation in beating-heart surgery by providing appropriate position guidance and environmental force feedback to the human operators.

Time delay compensation for nonlinear bilateral teleoperation: A motion prediction approach

This paper addresses the time delay compensation problem for nonlinear teleoperation system. A novel motion prediction approach is proposed based on a state observer with a cascade structure. The actual positions of master robot are estimated on the slave side by using delayed information of measurements. The prediction errors remain bounded under an appropriate set of assumptions for the system uncertainties. Moreover, an essential theorem for slave controller design is proposed to demonstrate performance recovery of the closed-loop system with cascade observer. By using the predictions, the forward time delay is effectively compensated when we design the controller of slave robot. Simulations are performed to verify the effectiveness of proposed method. The prediction results are highlighted through comparing with other two kinds of cascade predictors.

Teleoperation of robots carrying current intensity via electromagnetic fields – A quantum mechanical analysis

The master robot carries a current which is modeled as the sum of a classical current Jmc(t,r) and a quantum fluctuation current described by the Dirac field ψm(t,r) of electrons and positrons. The radiation field produced by this current interacts with the slave current and described by the sum of a classical current Jsc(t,r) and a quantum fluctuation current ψs(t,r). The motion of the master and slave robots with these interaction terms is described and techniques for calculating quantum fluctuations in the Euler angles are described. The obtained results show the efficacy of the proposed method.

Bilateral telerobotic system using Type-2 fuzzy neural network based moving horizon estimation force observer for enhancement of environmental force compliance and human perception

This paper firstly develops a novel force observer using Type-2 Fuzzy Neural Network (T2FNN)-based Moving Horizon Estimation (MHE) to estimate external force/torque information and simultaneously filter out the system disturbances. Then, by using the proposed force observer, a new bilateral teleoperation system is proposed that allows the slave industrial robot to be more compliant to the environment and enhances the situational awareness of the human operator by providing multi-level force feedback. Compared with existing force observer algorithms that highly rely on knowing exact mathematical models, the proposed force estimation strategy can derive more accurate external force/torque information of the robots with complex mechanism and with unknown dynamics. Applying the estimated force information, an external-force-regulated Sliding Mode Control (SMC) strategy with the support of machine vision is proposed to enhance the adaptability of the slave robot and the perception of the operator about various scenarios by virtue of the detected location of the task object. The proposed control system is validated by the experiment platform consisting of a universal robot (UR10), a haptic device and an RGB-D sensor.

Human-inspired stable bilateral teleoperation of mobile manipulators

This paper presents a novel strategy for delayed bilateral teleoperation of mobile manipulator robots. The strategy is based on the hypothesis that if the slave robot behaves similarly as the operator would do to the same task, the operator’s perception of the system states improves, and therefore the performance of the task is better. The proposed scheme allows controlling in simultaneously the mobile platform and the manipulator robot employing a single master device and maintaining the stability of the system against variable and asymmetric communication time delays. Stability guidelines based on Lyapunov–Krasovskii method are provided for the adjustment of the delayed system. Besides, a new control allocation strategy is proposed founded on the study of human movement in a task of navigation–pick and place. Finally, the performance of the proposal is compared with the standard switched control using a real robotic platform. As a result in practice, the proposed scheme is easier and more intuitive for the operator, besides it allows to reduce significantly the time necessary to complete the task.

A robot-assisted cutting surgery of human-like tissues using a haptic master operated by magnetorheological clutches and brakes

This study presents the preliminary experimental results of a robot-assisted surgery system featuring a six-degrees-of-freedom (6-dof) haptic master activated by magnetorheological (MR) actuators. The haptic master is designed to have a parallel mechanism to achieve structural stability and decoupled dynamic equations for translational and rotational motions. The translational motion is generated by MR clutches to achieve the repulsive force, while the rotational motion is generated by MR brakes to achieve the repulsive torque. After analyzing both the kinematic and dynamics equations of the slave robot, it is integrated with the haptic master. Subsequently, a feedback control system is established to achieve accurate tracking performance of the end-effector of the robot, and the desired motions are presented by dynamic animations and simulations. Further, a simple cutting surgery is performed on porcine specimens to demonstrate the effectiveness of the proposed haptic master-robot surgical system. A triangle-shaped section of the tumor is marked and dyed with black color on each specimen, and the cutting surgery to remove the tumor is performed, with and without the haptic feedback control system. It is observed that the surgical performance, in terms of surgical accuracy, achieved with the haptic feedback control system is much better than that obtained with only visual information without the haptic feedback signal.

Coordination Control of a Dual-Arm Exoskeleton Robot Using Human Impedance Transfer Skills

This paper has developed a coordination control method for a dual-arm exoskeleton robot based on human impedance transfer skills, where the left (master) robot arm extracts the human limb impedance stiffness and position profiles, and then transfers the information to the right (slave) arm of the exoskeleton. A computationally efficient model of the arm endpoint stiffness behavior is developed and a co-contraction index is defined using muscular activities of a dominant antagonistic muscle pair. A reference command consisting of the stiffness and position profiles of the operator is computed and realized by one robot in real-time. Considering the dynamics uncertainties of the robotic exoskeleton, an adaptive-robust impedance controller in task space is proposed to drive the slave arm tracking the desired trajectories with convergent errors. To verify the robustness of the developed approach, a study of combining adaptive control and human impedance transfer control under the presence of unknown interactive forces is conducted. The experimental results of this paper suggest that the proposed control method enables the subjects to execute a coordination control task on a dual-arm exoskeleton robot by transferring the stiffness from the human arm to the slave robot arm, which turns out to be effective.