Master Arm Research Articles

Development of a full ocean depth hydraulic manipulator with heavy-duty capacity

The underwater manipulator is a versatile tool commonly used for various underwater operations. In this study, we developed a heavy-duty hydraulic manipulator capable of operating at full ocean depth. The overall system design integrates both the mechanical structure and the electric control system. The master arm controls the slave arm by transmitting control signals to the controller and valve box. The structural design of the elbow and wrist joints has been optimized to enhance the manipulator's underwater performance and operational range. Laboratory tests demonstrated the manipulator’s excellent response consistency and tracking capability across a wide range of motion. During sea trials in the Mariana Trench, the manned submersible Fendouzhe successfully deployed the manipulator, showcasing its exceptional ability to complete complex tasks.

Coordinated control of free-floating dual-arm space robots based on hybrid task-priority approach

This paper addresses the problem of the coordinated control of the free-floating dual-arm space robots, in the case of multiple conflict tasks. Taking the dynamic coupling effect into consideration, a relative Jacobian matrix is presented to establish the kinematic model of the free-floating dual-arm space robot. Then, an adaptive coordinated controller is elaborately developed for three conflict tasks, including position tracking of the master arm, relative motion of dual arms, and obstacle avoidance. Owing to the hybrid task-priority approach, the proposed controller can effectively ensure the execution of the obstacle avoidance task without sacrificing the performance of the first two tasks. In addition, the singularity problem is settled via introducing an adaptive damping factor based damped least-squares inverse. Meanwhile, a novel hyperbolic tangent function is designed to handle the discontinuity in performing the null space task. Finally, numerical simulations were constructed to compare the performance of the proposed coordinated controller based on hybrid task-priority approach with the controller based on task-priority approach. The simulation results show that the proposed controller has an improved tracking performance of the master arm and safety performance, compared with single task-priority approach.

A dual-arm manipulation strategy using position/force errors and Kalman filter

This paper presents a new coordination manipulation strategy for a custom-made dual-arm robot. With master and slave coordination infrastructure, both spatial relation and sense of touch are considered to hold an object stably. Given the known trajectory of the master arm, the slave arm fuses position and force commands by using the Kalman filter to yield optimal compensation amounts. The proposed strategy has been experimentally evaluated, and the results confirm that it was capable of dealing with fragile and flexible objects. In addition, the influence of the loop time of the digital controller on force control for this task was also investigated in mathematical and simulated ways. Furthermore, a series of experiments were designed to explore the effects that have influences on errors in force control. The main factors that affect force control error were analyzed.

Coordinated compliance control of dual-arm robot astronaut for payload operation

Dual-arm robot astronaut has more general and dexterous operation ability than single-arm robot, and it can interact with astronaut more friendly. The robot will inevitably use both arms to grasp payloads and transfer them. The force control of the arms in closed chains is an important problem. In this article, the coordinated kinematic and dynamic equations of the dual-arm astronaut are established by considering the closed-chain constraint relationship. Two compliance control methods for dual-arm astronaut coordinated payload manipulating are proposed. The first method is called master–slave force control and the second is the shared force control. For the former, the desired path and operational force of the master arm should be given in advance and that of slave arm are calculated from the dual-arm robot closed-chain constraint equation. In the share control mode, the desired path and end operational force of dual arms are decomposed from the dual-arm robot closed-chain constraint equation directly and equally. Finally, the two control algorithms are verified by simulation. The results of analysis of variance of the simulation data show that the two control methods have no obvious difference in the accuracy of force control but the second control method has a higher position control accuracy, and this proves that the master–slave mode is better for tasks with explicit force distribution requirements and the shared force control is especially suitable for a high-precision requirement.

The Implementation of Bilateral Control Symmetrical Position, Force Reflection and Feedback Force on the Haptic Manipulator

Humans often encounter obstacles in doing their work. Especially if the work is related to an emergency situation that concerns the safety of human life, it needs quick and appropriate handling. Telerobotic technology that has a haptic function is one solution to these problems. In this study a system of 1 DOF haptic manipulator with slave master configuration was developed using bilateral haptic manipulator control. In bilateral control the position and information are transmitted in two directions between two manipulators. Position information is obtained using a potentiometer and force information is obtained by representing the force with the current using the WCS2702 sensor. There are three control methods used, namely bilateral symmetrical position control, bilateral reflection force control and force feedback bilateral control. The best method of control is the bilateral feedback force control. In the force feedback bilateral control system, the slave can move following the master movement with a ± 2° position error. When the slave arm is held by a hard object, the master arm is also restrained with ± 11° position error. Whereas when the slave arm is held by a soft object, the reflection of the object is felt by the master arm with ± 10 position error. Movement of the master and slave arms is lighter than using bilateral control of symmetrical position.

Peg-in-hole assembly based on master-slave coordination for a compliant dual-arm robot

PurposeThe paper aims to propose an assembly scheme based on master–slave coordination for a compliant dual-arm robot to complete a peg-in-hole assembly task.Design/methodology/approachThe proposed assembly scheme is inspired by the coordinated behaviors of human beings in the assembly process. The left arm and right arm of the robot are controlled to move alternately. The fixed arm and the moving arm are distinguished as the slave arm and the master arm, respectively. The position control model is used at the uncontacted stage, and the torque control model is used at the contacted stage.FindingsThe proposed assembly scheme is evaluated through peg-in-hole assembly experiments with different shapes of assembly piece. The round, triangle and square assembly piece with 0.5 mm maximum clearance between the peg and the hole can be assembled successfully based on the proposed method. Furthermore, three assembly strategies are investigated and compared in the peg-in-hole assembly experiments with different shapes of assembly piece.Originality/valueThe contribution of this study is that the authors propose an assembly scheme for a compliant dual-arm robot to overcome the low positioning accuracy and complete the peg-in-hole assembly tasks with different shapes parts.

Архитектура тренажерной системы подготовки операторов радиационно стойких манипуляторов

Nowadays Industrial robots of different kinematic structures and functionality are widely used nowadays in different areas of industry and most of them function autonomously with preprogrammed set of actions or typical trajectories. Some special purposes mobile and stationary robots are human-controlled and in most cases require qualified operator skills. For example, in nuclear industry the mechanical and electro-mechanical “master arm – slave arm” manipulators are widely used. Modern approaches of control systems and human machine interfaces designs allow to eliminate direct copy of kinematic configuration of manipulator arms, add semi-automatic and automated control modes. Key feature of such manipulator systems is a presence of human in control loop, by reason of variety and complexity of manipulations and, in some cases, non-deterministic environment. Due to these factors, it is very desirable to form operator sustainable skills to control such manipulators, including learning process using training systems. This article describes general approaches and practical aspects of the operator training and qualification system for arm-based special purpose manipulators. The set of training system functions include: general manipulator control (basic motion) and grasping actions, manipulator operations in restricted working areas, operator actions using virtual reality helms and multi-monitor visualization, etc. The hardware and software architecture of training system should allow effective training process and teamwork of trainee and instructor to reach good results. The paper proposes ROS-based software part of training system with description of inter-process communication messages, data formats, integration with database and following analysis of trainee action.

Robot Arm Analysis based on Master Device Pneumatic Actuators

Advances in technology have expanded the use of soft actuators in various fields especially in robotics, rehabilitation and medical field. Soft actuator development provides many advantages, primarily being simple structures, high power to weight ratio, good compliance, high water resistance and low production cost. However, most soft actuators suffer the problem of being oversized which could potentially hurt users as it is often made of hard materials such as steels and hard rigid plastics. Current drawbacks of soft actuator implementation in robotic arms are on its excessive weights, causing these robots to be difficult to set up by patients themselves which in turn makes it less applicable for home rehabilitation training program. Hence, there is a need to design a soft actuator which is safe and more flexible, especially for applications in areas of patients in rehabilitation area or in-house rehabilitation program. In this paper, we propose the design of robot arm using master device pneumatic actuator and analyse the implementation for the above purpose. The system comprises primarily of the master and slave arms, two accelerometers and two potentiometers providing references for attitude control, six quasi-servo valves, and SH-7125 microcontroller. Our proposed design exhibits functions of the actuator that has been generated from elastic deformation of extension and contraction of the cylinder structure when high pneumatic pressure is supplied to the chamber. The control performance of the device is investigated using simulation method, whereby the rational model of the robot arm and the quasi servo valve with the embedded controller is implemented and analysed. It is found that the analysed results of the model approved well with the desired values.

수중 매니퓰레이터 조작을 위한 텐던 기반 햅틱 마스터 장치 기구 설계

Underwater manipulation is difficult to completely automate the manipulator movement due to the nature of the work environment, and it is essential to operate the manipulator through a planar view through the camera, so that a master device capable of intuitive manipulation is essential. In this paper, we propose a tendon-based haptic master device for intuitive manipulation of commercial underwater manipulators and perform instrument design. We have optimized the master arm and button layout for the manipulation of 7 degrees of freedom underwater manipulator and proposed a small tendon drive module which can measure force to apply haptic feedback to all joints and can easily change the stiffness and output. The prototype was fabricated and the simulator and actual manipulator manipulation test were performed to verify the design.

Fully automatic visual servoing control for work-class marine intervention ROVs

ROVs with hydraulic manipulators are extensively used for subsea intervention. With camera feedback from the scene, manipulators are teleoperated and slaved to pilot held master arms. While standard for offshore oil and gas, for challenging applications in waves or currents a new approach is required. We present development of robot arm visual servo control approaches used in manufacturing and the transfer and adaption of these to underwater hydraulic manipulators. This is the first time a visual servoing algorithm for automated manipulation has been developed and verified, through subsea trials, on a commercial work-class ROV with industry standard hydraulic manipulators.

Motion mapping of the heterogeneous master–slave system for intuitive telemanipulation

Heterogeneous master–slave robots are widely used as both the assistive robot system for the elder/disabled people and the teleoperation robot system in dangerous environments. For the sake of intuitive teleoperation, motion mapping should be applied to keep the slave arm possessing the similar configuration of the master arm in the whole course of telemanipulation. We propose a motion mapping on the joint analog level based on unit dual quaternions (UDQs) for the telecontrol of a heterogeneous slave robot arm via the motion of human master arm. First, we analogize the links of the slave robot to the links of the human master arm, and accordingly group the slave arm joints into “shoulder,” “elbow,” and “wrist” joint analog sets. Then, we capture the motion of the human master arm via a wearable motion capture system and take it as the motion order of the slave arm. Finally, we solve the motion of slave robot arm’s joint via UDQ-based 1-, 2-, and 3-Degree of freedom (DOF) orientation error UDQ decomposition algorithms that are suit for solving a typical class of robotic slave arms. As a result, the operator can manipulate the heterogeneous robot system intuitively and conveniently, and the fatigue degree and error rate of the user can be significantly reduced, and thus the safety of teleoperation in an unstructured and constrained environment can be significantly improved.

Development master arm of 2-DOF planar parallel manipulator for In-Vitro Fertilization

Micromanipulator is a mechanical device used for manipulating miniature objects in the order of micron. It is widely used in In-Vitro Fertilization (IVF) in which sperms will be held in a micro-needle and penetrate to an oocyte for fertilization. IVF needs to be performed by high skill embryologists to control the movement of the needle accurately due to the lack of tactile perception of the user. Haptic device is a device that can transmit and simulate position, velocity and force in order to enhance interaction between the user and system. However, commercially available haptic devices have unnecessary degrees of freedom and limited workspace which are inappropriate for IVF process. This paper focuses on development of a haptic device for using in IVF process. It will be used as a master arm for the master-slave system for IVF process in order to enhance the ability of users to control the micromanipulator. As a result, the embryologist is able to carry out the IVF process more effectively with having tactile perception.

Implementing pseudo haptic feedback in a semi-isometric master interface for robotic surgery

We have developed a master interface that uses an isometric velocity control technique for translation and an anisometric position control technique for rotation. Using the developed interface, the operator can concentrate on the slave side and control the robot without repositioning required in conventional master arm due to the workspace limitation. However, it cannot display haptic to the operator for the translation directions with the manipulator. In this article, we propose a method to feedback the external force on the slave side to the master manipulator without using actuators or link mechanism but using a pseudo haptic effect. A flexible wrist joint with a spring is used at the tip of the slave forceps to enhance visual effect. The spring stiffness is pneumatically controlled. At the same time, we change the reference velocity of the slave according to the external force applied to the slave manipulator. The changed velocity caused by the external force restrains the slave motion. Using both the visual feedback and the motion restrain, the master–slave system is able to display force to the operator as pseudo haptic feedback without actuators. Experiments of pulling suture threads are executed using the developed master–slave surgical robot. It is confirmed that the master–slave system with pseudo haptic feedback can decrease the variance of force.

Geometric parameter identification of a dual-arm robot by using closed-chain constraint and optimization technique

The positioning accuracy of the empirical robot manipulators is determined by various factors, such as kinematic accuracy, structure rigidity, and controller performance. Here, we report on the development of a new and straightforward technique to calibrate the kinematic parameters of a dual-arm robot under uncertainty. In comparison with other techniques, which generally rely on using other instruments to calibrate the manipulators, the proposed method utilizes the intrinsic characteristics of the dual-arm robot for calibration. In particular, when the two arms grasp each other, a formed closed chain can be operated as the constraint equation for the kinematic parameter optimization of the two arms. In the optimization process, the dual-arm robot has to pose in various configurations to yield better performance, and thus a motion generation strategy of the dual-arm robot is proposed, where one arm serves as the master to track the designated trajectory and the other arm serves as the slave to track the motion of the master arm by using a compliance control strategy. The proposed calibration method was experimentally validated, and the results confirm that the positioning accuracy of both arms can be improved.

Development of a Virtual Platform for Telepresence Control of an Underwater Manipulator Mounted on a Submersible Vehicle

This paper develops a virtual platform of an underwater manipulator mounted on a submersible vehicle via the three-dimensional simulator “Webots” for teleoperation through a replica master arm. The graphical, kinematic, and dynamic models of the manipulator refer to a master–slave servo hydraulic manipulator with seven functions, consisting of six degrees of freedom and a parallel gripper, while the “Jiaolong” deep-manned submersible vehicle, operating below the sea surface down to 7000 m, is chosen as the underwater manipulator carrier. This study uses the virtual platform for training an operator to telepresence control the virtual manipulator to complete basic tasks in subsea environments. When training the operator, one has to consider uncertain external disturbances and the visual impacts that stem from subsea environments. In order to demonstrate the feasibility and effectiveness of the virtual platform, one designs two typical underwater operational tasks: grasping a marine organism sample and reaching at a given position. This paper presents the comparative studies: 1) the performances demonstrated by remotely controlling the virtual manipulator and the real manipulator; 2) the operating performances delivered by three operators before and after training when using the platform.

Bilateral Control of Flexible Master-Slave Arms with Time-Varying Delay Affected by Contact Force from Obstacle

A bilateral control system for flexible master-slave arms with time-varying delay affected by contact force from an obstacle is considered in this study. The proposed bilateral control system is constructed using a rigid master arm, a flexible slave arm actuated by a high-geared servomotor, and a communication network that causes the time-varying delay. The flexible slave arm is affected by contact force from the obstacle during motion. PD and PDS controllers are designed for controlling the rigid master and flexible slave arms, respectively. A Lyapunov function is used in order to prove the stability and passivity of the proposed system. Finally, performance of the proposed bilateral control system is verified by numerical simulations.

LED 광통신을 적용한 마스터 암과 수중 매니퓰레이터의 통합 제어

LED 광통신을 적용한 마스터 암과 수중 매니퓰레이터의 통합 제어

A user friendly method for image based acquisition of constraint information during constrained motion of Servo manipulator in hot-cells

In master slave manipulator, slave arm is controlled by an operator to manipulate the objects in remote environment using an iso-kinematic master arm which is located in the control room. In such a scenario, where the actual work environment is separated from the operator, formulation of techniques for assisting the operator to execute constrained motion (preferential inclusion or preferential exclusion of workspace zones) in the slave environment are not only helpful, but also essential. We had earlier demonstrated the efficacy of constraint motion with predefined geometrical constraints of various types. However, in a hot-cell scenario the generation of the constraint equations is difficult since we shall not have access to the cell for taking measurements. In this paper, a user friendly method is proposed for image based acquisition of the various constraint geometries thus eliminating the need to take in-cell measurements. For this purpose various hot cell tasks and required geometrical primitives pertaining to these tasks have been surveyed and an algorithm has been developed for generating the constraint geometry for each primitive. This methodology shall increase the efficiency and ease of use of the hot cell Tele-manipulator by providing real time constraint acquisition and subsequent assistive force based constrained motion.

配電作業用ロボットにおけるHRI(Human Robot Interface)の改良

We are developing a autonomous robot system for power distribution line maintenance works. The robot system is multi agent system composed of 6 agents and 2 databases. It is desirable to work the robot in order to carry out autonomous. However, the robot will always work, but you will not be able to run is autonomously generated. This study is intended to improve the operability.In this paper, at the same time by using the joystick as a master arm. Smooth proposes a method of operating a robot.Robot arm, the vehicle, the gripper are operated using the master arm.

산업용 로봇 팔 제어를 위한 마스터 암 설계 및 제어

In this paper, a new master arm was developed as an input device of the remote control system for easy control of the industrial robot arm; it has a structure similar to the robot arm and is easy to wear. For control of the slave arm, related equations were derived about the joints between the master and slave arm; and thereby using them, the master arm control system was developed. Furthermore, a control simulator was developed for the convenient and accurate control of the slave arm. Experiments, about controlling the slave arm in applying the master arm, were performed to validate the developed simulator and the derived related equations.