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The purpose of this paper is to analyse of structures made in rock mass with multiple intersecting discrete discontinuities such as joint, fault, shear plane.

In this study, a numerical method is proposed for analyzing multiple intersecting joints with varying dip angles, spacing and roughness in eXtended Finite Element Method platform. A procedure is also outlined to treat excavated enhanced (jointed) elements for analysing the effect of excavation sequences.

The proposed method is compared with the existing interface element methods (Phase-2 model) by considering the stress and displacement distributions of a multiple intersecting jointed rock sample under uniaxial loading conditions. A circular tunnel in rock mass having intersecting joints is also analyzed for the distribution of mobilised friction angle of joints and results are compared with a derived analytical solution.

Nucleation and propagation of cracks should be incorporated into the proposed framework in future studies.

The proposed method is a useful tool for rock mechanics and geotechnical engineering problems to analyse strength and deformability of jointed rock masses.

The paper enumerates concepts and detail implementation procedures of the proposed method in three-noded triangular elements. The intersection of joints is formulated in such a way that no additional (junction) enrichment is required in model. The method has been improved for inclusion of Dirichlet and Neumann boundary conditions to be applied in the enhanced part of a problem domain.

The purpose of this paper is to investigate the mechanical, kinematic and biological aspects that would be required for a customized upper limb exoskeleton prototype operation.

The research contained a literature survey, design, simulation, development and testing of an exoskeleton arm.

An adjustable/customizable exoskeleton arm was developed with a kinematic model to allow the desired motion. Tests were performed to determine the feasibility of the system.

The paper shows how the authors researched, designed and developed an exoskeleton arm that had similar mechanical properties to those of a biological arm. The exoskeleton must allow customization and be adaptable to the operator, without the need for major alterations.

Surgical robotics can be divided into two groups: specialized and versatile systems. Versatile systems can be used in different surgical applications, control architectures and operating room set‐ups, but often still based on the adaptation of industrial robots. Space consumption, safety and adequacy of industrial robots in the unstructured and crowded environment of an operating room and in close human robot interaction are at least questionable. The purpose of this paper is to describe the DLR MIRO, a new versatile lightweight robot for surgical applications.

The design approach of the DLR MIRO robot focuses on compact, slim and lightweight design to assist the surgeon directly at the operating table without interference. Significantly reduced accelerated masses (total weight 10 kg) enhance the safety of the system during close interaction with patient and user. Additionally, MIRO integrates torque‐sensing capabilities to enable close interaction with human beings in unstructured environments.

A payload of 30 N, optimized kinematics and workspace for surgery enable a broad range of possible applications. Offering position, torque and impedance control on Cartesian and joint level, the robot can be integrated easily into telepresence (e.g. endoscopic surgery), autonomous or soft robotics applications, with one or multiple arms.

This paper considers lightweight and compact design as important design issues in robotic assistance systems for surgery.

When the mobile manipulator is traveling on an unconstructed terrain, the external disturbance is generated. The load on the end of the mobile manipulator will be affected strictly by the disturbance. The purpose of this paper is to reject the disturbance and keep the end effector in a stable pose all the time, a control method is proposed for the onboard manipulator.

In this paper, the kinematics and dynamics models of the end pose stability control system for the tracked robot are built. Through the guidance of this model information, the control framework based on active disturbance rejection control (ADRC) is designed, which keeps the attitude of the end of the manipulator stable in the pitch, roll and yaw direction. Meanwhile, the control algorithm is operated with cloud computing because the research object, the rescue robot, aims to be lightweight and execute work with remote manipulation.

The challenging simulation experiments demonstrate that the methodology can achieve valid stability control performance in the challenging terrain road in terms of robustness and real-time.

This research facilitates the stable posture control of the end-effector of the mobile manipulator and maintains it in a suitable stable operating environment. The entire system can normally work even in dynamic disturbance scenarios and uncertain nonlinear modeling. Furthermore, an example is given to guide the parameter tuning of ADRC by using model information and estimate the unknown internal modeling uncertainty, which is difficult to be modeled or identified.

In large equipment and highly complex confined workspaces, the maintenance is usually carried out by snake-arm robots with equal cross-sections. However, the equal cross-sectional design results in the snake arm suffering from stress concentration and restricted working space. The purpose of this paper is to design a variable cross-section elephant trunk robot (ETR) that can address these shortcomings through bionic principles.

This paper proposes a cable-driven ETR to explore the advantages and inspiration of variable cross-section features for hyper-redundant robot design. For the kinematic characteristics, the influence of the variable cross-section design on the maximum joint angle of the ETR is analysed using the control variables method and the structural parameters are selected. Based on the biological inspiration of the whole elephant trunk following the movement of the trunk tip, a trajectory-tracking algorithm is designed to solve the inverse kinematics of the ETR.

Simulation and test results show the unique advantages of the proposed variable cross-section ETR in kinematics and forces, which can reduce stress concentrations and increase the flexibility of movement.

This paper presents a design method for a variable cross-section ETR for confined working spaces, analyses the kinematic characteristics and develops a targeted trajectory control algorithm.

The aim of this paper is the development of a modular robotic system for generic industrial applications, including assembly.

A library of robotic modules has been designed; they are divided into two categories: link modules, not actuated, and joint modules, actuated; the library is characterized by a relatively low number of elements, but allows the assembly of a wide variety of medium‐size serial robots.

The prototypes of two joint modules (a revolute joint module and a wrist module) and of some link modules have been realized. The behaviour of several serial robots composed of the designed modules has been assessed by multibody simulation. The results confirm the goodness of the proposed approach.

The two prototype modules are under test in combination with simplified modules. The further steps of the research programme will be the completion of the prototype library, and an experimental campaign on different serial chains.

Modularity allows one to achieve a great variety of robots starting from a small set of modules, in order to match different operative requirements. Moreover, modularity dramatically reduces the time‐to‐repair of the robot and consequently improves its overall availability; this is a fundamental feature for modern industrial enterprises aiming at maximizing the resources availability.

The proposed mechanical design of the revolute joint modules, based on a harmonic drive that connects two bodies in relative rotational motion, is compact and robust. Modularity is not restricted to mechanics: a distributed control system is adopted to make the reconfiguration of the robot easier and quicker.

Developing general closed-form solutions for six-degrees-of-freedom (DOF) serial robots is a significant challenge. This paper thus aims to present a general solution for six-DOF robots based on the product of exponentials model, which adapts to a class of robots satisfying the Pieper criterion with two parallel or intersecting axes among its first three axes.

The proposed solution can be represented as uniform expressions by using geometrical properties and a modified Paden–Kahan sub-problem, which mainly adopts the screw theory.

A simulation and experiments validated the correctness and effectiveness of the proposed method (general resolution for six-DOF robots based on the product of exponentials model).

The Rodrigues rotation formula is additionally used to turn the complex problem into a solvable trigonometric function and uniformly express six solutions using two formulas.

This paper presents a concept for a micro‐assembly station and shows different possibilities for increasing the positioning accuracy. The main part of the station consists of a spatial parallel structure with three translational degrees of freedom. An additional rotational axis is integrated into the working platform. This structure is constructed with low friction joints, which are nearly free of backlash. The construction of these high precision joints is presented and the characteristics of the robot such as workspace and resolution are discussed. After this an approach for increasing the accuracy of parallel robots by integrating flexure hinges into the structure is described.

To improve the trajectory tracking accuracy of 6R decoupled manipulator in singularity region, this paper aims to propose a singularity avoidance algorithm named “singularity separation plus improved Gaussian distribution damped reciprocal”.

The manipulator is divided into forearm and wrist, and the corresponding singularity factors are separated based on kinematics calculation. Singularity avoidance is achieved by replacing the common reciprocal with the improved Gaussian distribution damped reciprocal.

Compared with common damped reciprocal algorithm and classical Gaussian distribution algorithm, the continuity of the proposed algorithm is improved and the tracking error is minimized. The simulation and experiment results prove effectiveness and practicability of the proposed algorithm.

This study has an important significance to improve the efficiency and operation accuracy of 6R decoupled manipulator.

The purpose of this paper is to improve the positioning accuracy of 6-Dof serial robot by the way of error compensation and sensitivity analysis.

In this paper, the Denavit–Hartenberg matrix is used to construct the kinematics models of the robot; the effects from individual joint and several joints on the end effector are estimated by simulation. Then, an error model based on joint clearance is proposed so that the positioning accuracy at any position of joints can be predicted for compensation. Through the simulation of the curve path, the validity of the error compensation model is verified. Finally, the experimental results show that the error compensation method can improve the positioning accuracy of a two joint exoskeleton robot by nearly 76.46%.

Through the analysis of joint error sensitivity, it is found that the first three joints, especially joint 2, contribute a lot to the positioning accuracy of the robot, which provides guidance for the accuracy allocation of the robot. In addition, this paper creatively puts forward the error model based on joint clearance, and the error compensation method which decouples the positioning accuracy into joint errors.

It provides a new idea for error modeling and error compensation of 6-Dof serial robot. Combining sensitivity analysis results with error compensation can effectively improve the positioning accuracy of the robot, and provide convenience for welding robot and other robots that need high positioning accuracy.