Master Robot Research Articles

Design of a 6-DOF Master Robot for Robot-Assisted Minimally Invasive Surgery

Design of a 6-DOF Master Robot for Robot-Assisted Minimally Invasive Surgery

Workspace and dexterity analysis of the hybrid mechanism master robot in Sinaflex robotic telesurgery system: An in vivo experiment.

Sinaflex robotic telesurgery system has been introduced recently to provide ergonomic postures for the surgeon along with dexterous workspace for robotic telesurgery. The robot is described, and the forward and inverse kinematics are derived and validated by an experiment. The robot and operational workspaces and their dexterity are investigated and compared using the data collected during a dog vasectomy robotic telesurgery by Sinaflex. According to the simulation results, the workspace of the end effector is as large as 914.56×105mm3, which can completely cover the ergonomic human hand workspace. The dexterity of the robot for the total and operational workspace is 0.4557 and 0.6565, respectively. In terms of the workspace size and the amount of dexterity, Sinaflex master robot can be considered a good choice to fulfil the requirements of the surgeon side robot in robotic telesurgery systems.

Chatter prediction for parallel mirror milling of thin-walled parts by dual-robot collaborative machining system

Thin-walled parts with double-sided features are widely used in the aerospace industry, but the machining of such parts still faces great challenges due to their weak rigid structure and the positioning errors caused by turning/re-clamping of the workpiece. For this purpose, a novel machining approach for parallel mirror robotic milling of thin-walled parts is proposed. Different from conventional single-sided milling, it can simultaneously machine both sides of the workpiece while avoiding the above problems and improving machining efficiency. However, the introduction of multiple cutting excitations makes the vibration behavior of the workpiece more complicated, thus making it difficult for the dynamic modeling of the dual-robot machining system. This paper aims to uncover the dynamic mechanism of chatter phenomenon in parallel mirror robotic milling process in consideration of the interaction of tool-workpiece-tool system. A dual-robot collaborative machining system is first developed for the milling of thin-walled workpiece, and the method of synchronous motion planning for dual robots is described. The slave robot synchronously follows the master robot and the two milling cutters mounted on tool flange of the robot are kept in mirror position. Over a tooth passing period, the engagement state of the cutters and the workpiece is analyzed considering the effect of rotation phase lag (RPL) between the twin cutters. After that, the vibration state and the corresponding instantaneous displacement of the workpiece can be expressed explicitly, then the dynamic resultant cutting force acting on the workpiece is calculated according to the mechanistic force model. Comprehensively considering the dynamic interaction of the tool-workpiece-tool system, multi-mode and position-dependent modal characteristics of thin-walled part, a time-varying delay differential equation is constructed and solved to explore the dynamical behavior of parallel mirror milling process. The predicted stability lobe diagram is validated by a series of parallel mirror milling tests on thin-walled PMMA plates. Comparisons of numerical and experimental results show that the dynamic model successfully predicts the chatter stability for the parallel mirror milling of thin-walled parts.

Multi-Objective Optimization and Redundant Joint Planning of Minimally Invasive Surgical Robot Master Hand

Multi-Objective Optimization and Redundant Joint Planning of Minimally Invasive Surgical Robot Master Hand

A visual imitation learning algorithm for the selection of robots’ grasping points

The short-run production and customization are increasingly common in the manufacturing industry, which results in the frequent adjustments of production lines. Industrial robots in these production lines are also required to quickly learn to perform new grasping tasks. However, the traditional approaches in grasping points selection, which rely on the geometric envelope models of objects in preset task space, can no longer meet the demands of fast-shifting production. Therefore, the present paper tackled the problem of grasping points selection with a novel CNN-based imitating learning framework. Our imitating model learns the correct grasping posture for objects from human grasping operations captured on camera. The experiments showed that this imitating learning algorithm can help a dual-arm robot master the correct grasping posture of an object within only 20 min. Compared to traditional geometric modeling-based methods, such as the pick-and-place module available in the Robot Operating System (ROS), this new approach can increase grasping planning efficiency by 26.1%.

Stability of tracking wheel mobile robot with teleoperation fuzzy neural network control system

The stability of the Tracking Wheel Mobile Robot with Teleoperation System and Path Following Method is discussed in this study. The path is to be tracked by the host computer which is the master robot. The response from the robot is captured on camera. As the slave robot approaches the target position, the camera captures the response robot’s position and as well as moving trajectory. The host computer receives all of the images, enabling mobile robot deviation recoveries. The slave robot can use teleoperation to follow the sensor based on the decisions made by the master robot. The Lyapunov function in the Fuzzy Neural Network (FNN) control structure assures the system’s stability and satisfactory performance. It supports a mobile robot’s ability to adhere to a reference trajectory without deviating from it. Finally, the outcome of the simulation demonstrates that our controller is capable of tracking different environmental conditions and maintaining stability.

A novel collaborative path planning algorithm for 3-wheel omnidirectional Autonomous Mobile Robot

Collaboration of multiple mobile robots becomes important in situations where collaborative tasks are required. For this purpose, a method including obstacle detection based on collaborative path planning of multiple Autonomous Mobile Robots (AMRs) has been developed. This study ensures the usability of collaborative omnidirectional AMRs technologies in various fields. In the study, novel path planning and obstacle avoidance algorithms are developed for collaborative mobile robots with omnidirectional mobility. Essentially, these algorithms include motion planning performed by obstacle avoidance with two identical 3-wheel omnidirectional mobile robots (TWOMR). Numerical calculations of the collaborative algorithm have been performed after the kinematic calculations, and tested algorithms developed for the proposed model. As a result, it has been observed that the path planning and obstacle avoidance algorithms developed for collaborative omnidirectional AMRs successfully follow the Master robot in the most efficient trajectory without collision and it has been observed that the developed method works with high accuracy.

Adaptive Control of a Master-Slave Based Robotic Surgical System With Haptic Feedback

A master-slave (M-S) based robotic surgical system with haptic feedback is presented in this work for natural orifice transluminal endoscopic surgery (NOTES) using an in-vivo robot. A novel dual-loop control, including closed-loop inverse kinematics (CLIK) and adaptive control with optimal control parameters, is developed for the slave robot to track a random trajectory upon updating the dynamic parameters of the slave robot. The interaction between the slave robot tip position and environment is controlled by an impedance controller that prevents damage to healthy tissues. Upon tracking a given desired 3D trajectory as input for the slave robot by the human operator handling the master robot, the slave robot-tissue interaction force is sensed as haptic feedback at the master side. Lyapunov direct method based stability analysis and performance evaluations involving both simulation and experimental studies prove the efficacy of our novelly developed M-S robotic system aiming NOTES regulated by the proposed adaptive control strategy with optimized control parameters. Note to Practitioners: The M-S based robotic surgical system is developed to perform NOTES using a cable-driven in-vivo robot attached to the tip of a flexible endoscope. It performs tissue manipulation as per the direction given by the operator. The inclusion of haptic imitates the NOTES performed using the in-vivo robot as conventional surgery. The developed system includes the following aspects: a) The adaptive control scheme with optimal control parameters; b) Interaction force between the slave robot and tissue environment is controlled using impedance control and given as haptic feedback to the surgeon; c) The proposed system can be potentially utilized for actual teleoperated surgery and surgical training for NOTES.

유압시스템을 사용한 고 하중 양팔 로봇의 모션 추종 성능 향상을 위한 슬라이딩 모드 제어

This paper presents the control implementation of a heavy-duty dual-arm robot, Accident Response Manipulator (ARMstrong), configured as teleoperated control by a master robot. The mater-slave configuration for remote operation in dangerous areas has been implemented. The master robot is an exoskeleton type such that an operator can wear it to control the slave. The slave robot is actuated by the hydraulic system, which generates high power but produces larger motion-tracking errors that suffer from nonlinearity. The dead zone of each joint is identified and compensated to improve motion-following performance after the master. Sliding mode control further improves the positional accuracy under unknown payloads. Experimental studies are conducted to demonstrate the position control performance of the ARMstrong slave robot.

Communication and Cooperation for Spherical Underwater Robots by Using Acoustic Transmission

The application of miniature underwater robots in the marine area is becoming more extensive. Occasionally, the ability of the single miniature underwater robot is limited by its size, configuration, function or propulsion method. At this moment, if a group of robots can work together in a division of labor, that can solve more problems underwater. For autonomous underwater vehicles, the support of underwater wireless communication equipment is required to achieve communication and collaboration. Acoustic communication equipment has generally been used in large underwater vehicles due to its large size and power. This article employs a small acoustic communication module to enable underwater communication in a spherical robot with a diameter of only 45 cm. The fourth-generation spherical underwater robot is exploited as the prototype. The article also verifies the accuracy, efficiency and timeliness of the proposed underwater communication systems. Finally, a cooperative mode is established based on the base station, master robot and slave robots, and some cooperation motion experiments are carried out to verify its effectiveness. Early work on this article was presented at the IEEE ICMA 2018 conference S. Gu et al., 2018. In this conference article, the authors only provided theoretical research and a small number of experiments. On this basis, this article has conducted in-depth research, proposed a base station-mater-slave robot communication mode, and established an instruction set for further experiments.

Robust complete synchronization control design for non‐collocated nonlinear master–slave system over delayed communication network

AbstractIn this article, a predictor‐based robust synchronization control scheme is proposed for a non‐collocated nonlinear master–slave system with any large networked communication time delays. In contrast to traditional collocated teleoperation systems, enhanced flexibility, and operation capacity will be obtained under the non‐collocated system structure in this article. Yet, due to the introduced input delays, existing control strategies for teleoperation systems are no longer applicable. Aiming at this problem, the terminal sliding mode (TSM) admittance control approach is proposed for the master robot to improve system transparency by receiving the contact force from the slave robot to the local side, first. Moreover, complete position synchronization performance is realized by developing a predictor‐based TSM control method for the slave robot while the closed‐loop system is subject to time‐variant large delays. It is mathematically proved that the synchronization errors between the master and the slave will converge to zero completely in finite time by compensating the effect of time delays. Finally, numerical simulations and comparisons are executed to illustrate the superior performance of the posed control algorithms.

Four-Arm Collaboration: Two Dual-Arm Robots Work Together to Manipulate Tethered Tools

This article presents a planner for a master dual-arm robot to manipulate tethered tools with the help of an assistant dual-arm robot. The assistant robot assists the master robot by manipulating the tool cable and avoiding collisions. The provided assistance allows the master robot to perform tool placements on the robot workspace table and regrasp it, which would typically fail since cable tension may change the tool positions. It also allows the master robot to perform tool handovers, which would normally cause entanglements or collisions with the cable and the environment without assistance. Simulations and real-world experiments are performed to validate the proposed planner. Experimental results show that with the help of the assistant dual-arm robot and the proposed method, the master robot obtained improved flexibility in working with tethered tools.

User study of sensorless adaptive haptic assistance for bilateral teleoperation

This paper presents a sensor-less haptic adaptive assistance scheme for bilateral shared controlled in telerobotics. The paper focuses on the implementation of an adaptive assistance scheme previously developed using force sensors at the master’s side, extending it to the case where this measurement is no longer available. The experimental setup was composed of a virtual slave robot and a real master robot (a commercially-of-the-shelf, low-cost haptic device), namely the Novint Falcon haptic device. Due to the lack of sensors to measure the contact force between the human operator and the haptic control device i.e., only the position of the master robot is measured, a data-driven Unknown Input Observer with disturbance estimation augmentation is proposed, allowing the estimation of the (external) human force under plant uncertainty and external disturbances. The proposed approach is tested via a path tracking (known) with (unknown) obstacle avoidance task, and statistical analysis regarding the scheme’s effectiveness is presented.

A Magnetorheological Fluid Based Force Feedback Master Robot for Vascular Interventional Surgery

A Magnetorheological Fluid Based Force Feedback Master Robot for Vascular Interventional Surgery

Adaptive control of time delay teleoperation system with uncertain dynamics.

A bilateral adaptive control method based on PEB control structure is designed for a class of time-delay force feedback teleoperation system without external interference and internal friction to study the uncertainty of dynamic parameters and time delay. The stability and tracking performances of the closed-loop constant time delay teleoperation system are analyzed by Lyapunov stability theory. Finally, the controller designed in this paper is successfully applied to the teleoperation system composed of a two-degree of freedom rotating manipulator as the master robot and the slave robot. The simulation is carried out in no operator and environment force or with operator and environment force. The adaptive bilateral control method's control performance is compared with that of the traditional time-delay teleoperation system. Finally, it is verified that the method has good control performance.

A Telepresence-Guaranteed Control Scheme for Teleoperation Applications of Transferring Weight-Unknown Objects

Currently, most teleoperation work is focusing on scenarios where slave robots interact with unknown environments. However, in some fields such as medical robots or rescue robots, the other typical teleoperation application is precise object transportation. Generally, the object's weight is unknown yet essential for both accurate control of the slave robot and intuitive perception of the human operator. However, due to high cost and limited installation space, it is unreliable to employ a force sensor to directly measure the weight. Therefore, in this paper, a control scheme free of force sensor is proposed for teleoperation robots to transfer a weight-unknown object accurately. In this scheme, the workspace mapping between master and slave robot is firstly established, based on which, the operator can generate command trajectory on-line by operating the master robot. Then, a slave controller is designed to follow the master command closely and estimate the object's weight rapidly, accurately and robust to unmodeled uncertainties. Finally, for the sake of telepresence, a master controller is designed to generate force feedback to reproduce the estimated weight of the object. In the end, comparative experiments show that the proposed scheme can achieve better control accuracy and telepresence, with accurate force feedback generated in only 500 ms.

Intuitive endoscopic robot master device with image orientation correction.

The camera of an endoscope is fixed to the device, and the image rotates together with the endoscope. This can lead to visual confusion for the user and incorrect image reading. The problem also occurs with endoscopic robots. Using a master device with the same degrees of freedom as the endoscope to control an endoscopic robot causes visual-motor misorientation, making intuitive control difficult. The roll misorientation between the image and master device handle was removed by measuring and correcting for the roll axis displacement of the master device. This enabled intuitive manipulation of the master device. The work speed and number of mistakes were experimentally measured with and without image correction. The tasks were completed significantly faster and more accurately with image orientation correction than without. The proposed method enables intuitive manipulation of the master device by correcting the image orientation in endoscopic robot control.

Resource Optimization in MEC-Assisted Multirobot Cooperation Systems

With prevalent utilization of multirobot cooperation (MRC) systems, people pay more attention to improve the system performance. Among them, the energy consumption and implementation latency of MRC systems are major concerns, and mobile edge computing (MEC) provides a potential way to solve these problems. Therefore, how to leverage MEC to get the balance between computing and communication consumption in MRC systems needs to be investigated urgently. In this paper, a MRC system deployed to accomplish multiple time-critical tasks by MEC technology is studied. The proposed MRC system includes a powerful master robot (MR) and several slave robots (SRs). As a scheduler, MR is responsible for allocating tasks to SRs and has more computing power. SRs are robots with sensors that interact with the environment. In this paper, we propose a strategy for task allocation and resource management in MRC systems. The results show that the proposed scheme can effectively reduce the total energy consumption in SRs.

Time-critical tasks implementation in MEC based multi-robot cooperation systems

Mobile edge computing (MEC) deployment in a multi-robot cooperation (MRC) system is an effective way to accomplish the tasks in terms of energy consumption and implementation latency. However, the computation and communication resources need to be considered jointly to fully exploit the advantages brought by the MEC technology. In this paper, the scenario where multi robots cooperate to accomplish the time-critical tasks is studied, where an intelligent master robot (MR) acts as an edge server to provide services to multiple slave robots (SRs) and the SRs are responsible for the environment sensing and data collection. To save energy and prolong the function time of the system, two schemes are proposed to optimize the computation and communication resources, respectively. In the first scheme, the energy consumption of SRs is minimized and balanced while guaranteeing that the tasks are accomplished under a time constraint. In the second scheme, not only the energy consumption, but also the remaining energies of the SRs are considered to enhance the robustness of the system. Through the analysis and numerical simulations, we demonstrate that even though the first policy may guarantee the minimization on the total SRs' energy consumption, the function time of MRC system by the second scheme is longer than that by the first one.

Sensors Allocation and Observer Design for Discrete Bilateral Teleoperation Systems with Multi-Rate Sampling.

This study addresses sensor allocation by analyzing exponential stability for discrete-time teleoperation systems. Previous studies mostly concentrate on the continuous-time teleoperation systems and neglect the management of significant practical phenomena, such as data-swap, the effect of sampling rates of samplers, and refresh rates of actuators on the system’s stability. A multi-rate sampling approach is proposed in this study, given the isolation of the master and slave robots in teleoperation systems which may have different hardware restrictions. This architecture collects data through numerous sensors with various sampling rates, assuming that a continuous-time controller stabilizes a linear teleoperation system. The aim is to assign each position and velocity signals to sensors with different sampling rates and divide the state vector between sensors to guarantee the stability of the resulting multi-rate sampled-data teleoperation system. Sufficient Krasovskii-based conditions will be provided to preserve the exponential stability of the system. This problem will be transformed into a mixed-integer program with LMIs (linear matrix inequalities). These conditions are also used to design the observers for the multi-rate teleoperation systems whose estimation errors converge exponentially to the origin. The results are validated by numerical simulations which are useful in designing sensor networks for teleoperation systems.