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This purpose of this paper is to design a peg-in-hole controller for a cable-driven serial robot with compliant wrist (CDSR-CW) using cable tensions and joint positions. The peg is connected to the robot link through a CW. It is required that the controller does not rely on any external sensors such as 6-axis wrist force/torque (F/T) sensor, and only the compliance matrix’s estimated value of the CW is known.

First, the peg-in-hole assembly system based on a CDSR-CW is analyzed. Second, a characterization algorithm using micro cable tensions and joint positions to express the elastic F/T at the CW is established. Next, under the premise of only knowing the compliance matrix’s estimate, a peg-in-hole controller based on force/position hybrid control is proposed.

The experiment results show that the plug contact F/T can be tracked well. This verifies the validity and correctness of the characterization algorithm and peg-in-hole controller for CDSR-CWs in this paper.

First, to the authors’ knowledge, there is no relevant work about the peg-in-hole assembly task using a CDSR-CW. Besides, the proposed characterization algorithm for the elastic F/T makes the peg-in-hole controller get rid of the dependence on the F/T sensor, which expands the application scenarios of the peg-in-hole controller. Finally, the controller does not require an accurate compliance matrix, which also increases its applicability.

Continuum manipulators are often used in complex and narrow space in recent years because of their flexibility and safety. Vision is considered to be one of the most direct methods to obtain its spatial shape. However, with the improvement of the cooperation requirements of multiple continuum manipulators and the increase of space limitation, it is impossible to obtain the complete spatial shape information of multiple continuum manipulators only by several cameras.

This paper proposes a fusion method using inertial navigation sensors and cameras to reconstruct the shape of continuum manipulators in the whole workspace. The camera is used to obtain the position information, and the inertial navigation sensor is used to obtain the attitude information. Based on the above two information, the shape of the continuum manipulator is reconstructed by fitting Bézier curve.

The experiment result of single continuum manipulator shows that the cubic Bézier curves is applicable to curve fitting of variable curvature, the maximum fitting error is about 2 mm. Meanwhile, the experiment result shows that this method is not affected by obstacles and can still reconstruct the shape of the continuum manipulators in 3-D space by detecting the position and attitude information of the end.

According to the authors’ knowledge, this is the first study on spatial shape reconstruction of multiple continuum manipulators and the first study to introduce inertial navigation sensors and cameras into the field of shape reconstruction of multiple continuum manipulators in narrow space. This method is suitable for shape reconstruction of manipulator with variable curvature continuum manipulator. When the vision of multiple continuum manipulators is blocked by obstacles, the spatial shape can still be reconstructed only by exposing the end point. The structure is simple, but it has certain accuracy within a certain range.

Supernumerary robotic limbs (SRLs) are a new type of wearable robot, which improve the user’s operating and perceive the user’s environment by extra robotic limbs. There are some literature reviews about the SRLs’ key technology and development trend, but the design of SRLs has not been fully discussed and summarized. This paper aims to focus on the design of SRLs and provides a comprehensive review of the ontological structure design of SRLs.

In this paper, the related literature of SRLs is summarized and analyzed by VOSviewer. The structural features of different types of SRLs are extracted, and then discuss the design approach and characteristics of SRLs which are different from typical wearable robots.

The design concept of SRLs is different from the conventional wearable robots. SRLs have various reconfiguration and installed positions, and it will influence the safety and cooperativeness performance of SRLs.

This paper focuses on discussing the structural design of SRLs by literature review, and this review will help researchers understand the structural features of SRLs and key points of the ontological design of SRLs, which can be used as a reference for designing SRLs.

The purpose of this paper is to introduce a robot mechanism designed for power transmission line inspection. The focus for this design is on obstacle-crossing ability with a goal to create a robot moving and crossing obstacle on not only the straight line but also the steering line.

A novel four-unit tri-arm serial robot mechanism is proposed. Every novel unit designed for pitching motion is based on parallelogram structure, which is driven by cables and only one motor. There is gripper-wheel compounding mechanism mounted on the arm. The prototype and obstacle environments are established, and the obstacle-crossing experiments are conducted.

The novel unit mechanism and robot prototype have been tested in the lab. The prototype has demonstrated the obstacle-crossing ability when moving and crossing fundamental obstacles on the line. The experimental results show that the robot mechanism meets the obstacle-crossing requirements.

The novel robot technology can be used for defect inspection of power transmission line by power companies.

It stands to lower the intense and risk of inspection works and reduce the costs related to inspection.

Innovative features include its architecture, mobility and driving method.

The purpose of this paper is to propose a screw axis identification (SAI) method based on the product of exponentials (POE) model, which is concerned with calibrating a serial robot with m joints equipped with a stereo‐camera vision system.

Different from conventional approaches, like the circle point analysis (CPA) or the system theoretic method which must collect a great deal of data, the identification of the joint parameters for the proposed method only needs to measure m+1 times for n (n≥3) target points mounted on the manipulator end‐effector.

In this approach, the joint parameter, called a screw or twist, together with the actual value of joint angle can be obtained by linearly solving a closed‐form expression. Further, this method avoids calibrating the hand‐eye relationship and the exterior parameter of the robot.

Finally, the stability and accuracy of the SAI method are evaluated by simulation experiments, and it is also verified well in practical experiments.

This paper aims to present the design and implementation of VirSense, a novel six-DOF haptic interface system, with an emphasis on its gravity compensation and fixed-base motors.

In this paper, the design and manufacture of the VirSense robot and its comparison with the existing haptic devices are presented. The kinematic analysis of the robot, design of the components, and manufacturing of the robot are explained as well.

The proposed system is employed to generate a Virtual Sense (VirSense) with fixed-base motors and a spring compensation system for counterbalancing the torques generated by the weight of the links. The fixed bases of the motors reduce the system's effective mass and inertia, which is an important factor in haptic interface systems. A novel cabling system is used to transmit the motor torques to the end-effector. The spring-based gravity compensation system causes more reduction in the effective mass and inertia.

This paper provides the details of the VirSense haptic device, its gravity compensation system, and a novel cabling power transmission.

The purpose of this paper is to introduce a development and error modeling of a serial redundant manipulator system applied in nuclear fusion environment. Detailed mechanical design of vacuum-compatible arms and actuators are presented, and manipulator flexibility is studied through experiments and model identification algorithm to evaluate the deformation.

First, the manipulator is designed to be several modular segments to obtain enough and flexible workspace inside the fusion device with narrow and complex geometries. Joint actuators with “rotation-linear-rotation” chains are developed to provide both huge reduction ratios and vacuum sealing. The redundant manipulator system has 11 degree of freedoms in total with a storage cask system to dock with the device vacuum vessel. In addition, to improve the position accuracy, an error prediction model is built based on the experimental study and back-propagation neural network (BPNN) algorithm.

Currently, the implementation of the manipulator system has been successfully carried out in both atmosphere and vacuum condition. Excellent performance indicates that the mechanical design is suitable. The validation of BPNN model shows an acceptable prediction accuracy (94∼98 per cent) compared with the real measurement.

This is a special robot system which is practically used in a nuclear fusion device in China. It will allow remote inspection and maintenance of plasma facing components in the vacuum vessel of fusion device without breaking the ultra-high vacuum condition during physical experiments. Its design, mechanism and error prediction strategy have great reference values to the similar robots in vacuum and temperature applications.

Pediatric disorders, such as cerebral palsy and stroke, can result in thumb-in-palm deformity greatly limiting hand function. This not only limits children's ability to perform activities of daily living but also limits important motor skill development. Specifically, the isolated orthosis for thumb actuation (IOTA) is 2 degrees of freedom (DOF) thumb exoskeleton that can actuate the carpometacarpal (CMC) and metacarpophalangeal (MCP) joints through ranges of motion required for activities of daily living. The paper aims to discuss these issues.

IOTA consists of a lightweight hand-mounted mechanism that can be secured and aligned to individual wearers. The mechanism is actuated via flexible cables that connect to a portable control box. Embedded encoders and bend sensors monitor the 2 DOF of the thumb and flexion/extension of the wrist. A linear force characterization was performed to test the mechanical efficiency of the cable-drive transmission and the output torque at the exoskeletal CMC and MCP joints was measured.

Using this platform, a number of control modes can be implemented that will enable the device to be controlled by a patient to assist with opposition grasp and fine motor control. Linear force and torque studies showed a maximum efficiency of 44 percent, resulting in a torque of 2.39±1.06 in.-lbf and 0.69±0.31 in.-lbf at the CMC and MCP joints, respectively.

The authors envision this at-home device augmenting the current in-clinic and at-home therapy, enabling telerehabilitation protocols.

This paper presents the design and characterization of a novel device specifically designed for pediatric grasp telerehabilitation to facilitate improved functionality and somatosensory learning.

Remote handling (RH) manipulators have been widely studied for maintenance tasks in fusion reactors. Those tasks always require heavy load, high accuracy and large work space for manipulators. Traditionally, the maintenance of fusion devices always depends on manual RH. With the development of calculating ability, the intelligent automatic maintenance makes it possible for a fusion device instead of the previous manual operation. As the flexibility of arm and the deformation of manipulator will cause problems, which are mainly inaccuracy and lower efficiency. This paper aims to study an effective way to promote the arm behavior to solve these problems.

By making use of the experimental advanced superconducting tokamak articulated maintenance arm as a platform, a series of experiments is designed to measure errors of kinematics and to collect the database of the flexible arm. Through studying the data and the arm structure, recurrent neural network (RNN) method was adopted to estimate the deformation of flexible arm and eventually compensate deformation in robot control to achieve higher accuracy.

By means of delicate RNN modeling, errors of kinematics have been reduced to a smaller order than the RH mode. This intelligent maintenance method will also reduce complexity of operations in maintenance.

This paper presents the use of an artificial intelligent algorithm to solve a nonlinear deformation problem of the flexible arm. The results demonstrate that it is efficient in dealing with this problem in fusion application. The RNN’s successful application has also shown that intelligent algorithms can be widely applied in fusion maintenance.

The application of robots to industrial problems often requires grasping and manipulation of the work piece. The robot is able to perform a task adequately only when it is assigned proper tooling and adequate methods of grasping and handling work pieces. The design of such a task requires an in‐depth knowledge of several interrelated subjects including: gripper design, force, position, stiffness and compliance control and grasp configurations. In this paper, we review the research finding on these subjects in order to present in a concise manner, which can be easily accessed by the designers of robot task, the information reported by the researchers, and identify based on the review, future research directions in these areas.