Search results

The purpose of this paper is to propose a universal approach for configuration synthesis of reconfigurable robots based on fault tolerant indices.

A universal approach is introduced to determine the best configuration of redundant reconfigurable robots based on fault tolerant indices. For a given task, a method based on genetic algorithm for evaluation on the index, fault tolerant workspace reachability, is employed first to search the robot configurations with the fault tolerant ability for the desired task. Then, among the obtained robot configurations, a method based on gradient projection algorithm is adopted to further find out the robot configuration that has the comparatively best fault tolerant operation dexterity. The validity of this approach is proved by conducting computational simulations.

A universal approach has been found for configuration synthesis of reconfigurable robots based on fault tolerant indices.

The paper introduces a universal approach for configuration synthesis of reconfigurable robots to not only guarantee the robot with the synthesized configuration possesses the fault tolerant ability for the given task, but also has relatively high fault tolerant operation dexterity.

The purpose of this paper is to present a new nested rapidly‐exploring random tree (RRT) algorithm for fault tolerant motion planning of robotic manipulators.

Another RRT algorithm is nested within the general RRT algorithm. This second nested level is used to check whether the new sampled node in the first nested level is fault tolerant. If a solution can be found in the second nested RRT, the reduced manipulator after failures at the new sampled node can still fulfill the remaining task and this new sampled node is added into the nodes of RRT in the first level. Thus, the nodes in the first level RRT algorithm are all fault tolerant postures. The final trajectory joined by these nodes is also obviously fault tolerant. Besides fault tolerance, this new nested RRT algorithm also can fulfill some secondary tasks such as improvement of dexterity and obstacle avoidance. Sufficient simulations and experiments of this new algorithm on fault tolerant motion planning of robotic manipulators are implemented.

It is found that the new nested RRT algorithm can fulfill fault tolerance and some other secondary tasks at the same time. Compared to other existing fault tolerant algorithms, this new algorithm is more efficient.

The paper presents a new nested RRT algorithm for fault tolerant motion planning.

The objective of this study is to enhance the usage of teleoperation fields, such as in nuclear site decommissioning or nuclear waste disposal, by designing a stable, dependable and fault‐tolerant teleoperation system in the face of “extraordinary” conditions. These “extraordinary” conditions can be classified as variable time delays in communications lines, usage of different robotic systems, component failures and changes in the system parameters during task execution.

This paper first gives a review of teleoperation systems developed earlier. Later, fault tolerance is proposed for use in teleoperation systems at the processor, actuator, sub‐system, and system levels. Position/force control algorithms are recommended to address stability issues when there is a loss in communications. Various other controls are also introduced to overcome the instability experienced when there is a time delay in the communications line.

Finally, this work summarizes the teleoperation system architecture and controller design options in terms of a flowchart to help in the conceptual design of such systems.

The impact of these new designs and algorithms will be to expand the limits and boundaries of teleoperation and a widening of its utilization area. Enhanced operation of these systems will improve system reliability and even encourage their use in more critical and diverse applications.

The purpose of this paper is to present the development of a Matlab/Simulink‐based simulation environment for the design and testing of indirect and direct adaptive flight control laws with fault tolerant capabilities to deal with the occurrence of actuator and sensor failures.

The simulation environment features a modular architecture and a detailed graphical user interface for simulation scenario set‐up. Indirect adaptive flight control laws are implemented based on an optimal control design and frequency domain‐based online parameter estimation. Direct adaptive flight control laws consist of non‐linear dynamic inversion performed at a reference nominal flight condition augmented with artificial neural networks (NNs) to compensate for inversion errors and abnormal flight conditions following the occurrence of actuator or sensor failures. Failure detection, identification, and accommodation schemes relying on neural estimators are developed and implemented.

The simulation environment provides a valuable platform for the evaluation and validation of fault‐tolerant flight control laws.

The modularity of the simulation package allows rapid reconfiguration of control laws, aircraft model, and detection schemes. This flexibility allows the investigation of various design issues such as: the selection of control laws architecture (including the type of the neural augmentation), the tuning of NN parameters, the selection of parameter identification techniques, the effects of anti‐control saturation techniques, the selection and the tuning of the control allocation scheme, as well as the selection and tuning of the failure detection and identification schemes.

The novelty of this research efforts resides in the development and the integration of a comprehensive simulation environment allowing a very detailed validation of a number of control laws for the purpose of verifying the performance of actuator and sensor failure detection, identification, and accommodation schemes.

The purpose of this paper is to describe design and development of a pole climbing robot (PCR) for inspection of industrial size pipelines. Nowadays, non‐destructive testing (NDT) methods are performed by dextrous technicians across high‐level pipes, frequently carrying dangerous chemicals. This paper reports development of a PCR that can perform in situ manipulation for NDT tests.

Introduces a PCR including a novel four‐degrees of freedom climbing serial mechanism with the nearly optimal workspace and weight, unique V‐shaped grippers and a fast rotational mechanism around the pole axis. Simplicity, safety, minimum weight, and manipulability were concerned in the design process.

The developed prototype proved possibility of application of PCRs for NDT inspection on elevated structures. Design and development of PCRs which are able to pass bends and T‐junctions faces much more difficulties than those which should climb from a straight pole.

The robot is successfully tested on an industrial size structure (exterior diameter of 219 mm) with bends and T‐junctions.

Design and development of a novel pole climbing and manipulating robot for inspection of industrial size pipelines. The robot is able to pass bends and T‐junctions. The V‐shaped grippers offer many advantages including safety and tolerance to power failure. After grasping the structure, in case of power failure in any of the grippers' motors, the robot does not slip on the structure. The Z‐axis rotational mechanism provides fast navigation around the pole which is not possible with the traditional serial articulated arms.

This paper sets out to outline a human hazard analysis methodology as a tool for managing human error in aircraft maintenance, operations and production. The methodology developed has been used in a slightly modified form on Airbus aircraft programmes. This paper aims to outline a method for managing human error in the field of aircraft design, maintenance and operations. Undertaking the research was motivated by the fact that aviation incidents and accidents still show a high percentage of human‐factors events as key causal factors.

The methodology adopted takes traditional aspects of the aircraft design system safety process, particularly fault tree analysis, and couples them with a structured tabular notation called a human error modes and effects analysis (HEMEA). HEMEA provides data, obtained from domain knowledge, in‐service experience and known error modes, about likely human‐factors events that could cause critical failure modes identified in the fault tree analysis. In essence the fault tree identifies the failure modes, while the HEMEA shows what kind of human‐factors events could trigger the relevant failure.

The authors found that the methodology works very effectively, but that it is very dependent on locating the relevant expert judgement and domain knowledge..

The authors found that the methodology works very effectively, but that it is very dependent on locating the relevant expert judgement and domain knowledge. Using the method as a prototype, looking at aspects of a large aircraft fuel system, was very time‐consuming and the industry partner was concerned about the resource implications of implementing this process. Regarding future work, the researchers would like to explore how a knowledge management exercise might capture some of the domain knowledge to reduce the requirement for discursive, seminar‐type sessions with domain experts.

It was very clear that the sponsors and research partners in the aircraft industry were keen to use this method as part of the safety process. Airbus has used a modified form of the process on at least two programmes.

The authors are aware that the UK MOD uses fault tree analysis that includes human‐factors events. However, the researchers believe that the creation of the human error modes effects analysis is original. On the civil side of the aviation business this is the first time that human error issues have been included for systems other than the flightdeck. The research was clearly of major value to the UK Civil Aviation Authority and Airbus, who were the original sponsors.

The purpose of this paper is to discuss an example of modelling with experiments of robot prototype with dependent joint concept, including a full description of related functionalities. Reduction in active degrees of freedom in a machine can lead to improved accuracy, improved reliability and lower cost. The reconfiguration of machines and systems is a key technology for future responsive manufacturing systems. The concept of dependent joints helps to implement much specified sub-workspaces depending on functional needs in the machine.

This is inherently made possible using smart mechanical concepts having embedded sensors and reconfigurable control systems. This paper introduces structural reconfiguration systems and discusses a sample approach to functional reconfiguration.

A successful manipulator design with extended features when considering reduction in active degrees of freedom in a machine would lead to specific sub-workspace with improved accuracy, improved reliability and lower cost.

Reduction in active degrees of freedom in a machine can lead not only towards a dedicated functional workspace but also towards improved accuracy, improved reliability and lower cost.

This paper is of value to engineers and researchers developing robotic manipulators for use in various aspects of industry.

Organisations use “space” to support the profitability of their business. The workplace and the space that organisations occupy is continuously evolving and transforming. There has been a general trend globally to provide less assigned space and more shared space for employees at higher occupational density. Studies have shown that the workplace setting can contribute to an employee's sense of well-being and increased productivity. The purpose of this paper is to permit a deeper understanding as to how knowledge workers evaluate their workspace within this changing environment.

The paper describes an integrated conceptual framework developed from a range of literature within the disciplines of property, psychology and facilities management. In order to investigate the pertinence of this framework a case study is undertaken comprising five one-to-one in-depth interviews with knowledge workers from an organisation that had recently relocated. The key changes between the original and newer premises in terms of space usage were the move from a more traditional layout incorporating larger desk space and eye-level partitioning to one incorporating a fit-out providing for a higher occupational density and a wider range of communal spaces.

The findings identify a number of evaluative criteria including workability, comfort, occupational density, the need for privacy, control over the environment, adjacency to colleagues and functionality, all previously identified in the literature. A further two criteria, location and customisability were also identified.

The study although incorporating a wide ranging literature review concentrates on employees within one company and given the makeup of employees the interviewees were all male thus not able to pick up gender differences.

The study provides stakeholders such as organisations, workplace consultants and design professionals with information about what knowledge workers value most in their workplace environment.

Most extant literature investigating the link between employees and their workplace has focused on specific aspects of the relationship. This research contributes to understanding workplace by taking an overall perspective and providing knowledge worker employees with an opportunity to compare two distinct workplace settings.

This paper aims to present a new kinematics mapping method based on dynamic equivalent points. In teleoperation, this method enables a robotic (follower) arm to mimic human (leader) arm postures and avoid obstacles in a human-like manner.

The information of the human arm is extracted based on the characteristics of human arm motion, and the concept of equivalent points is introduced. Then, an equivalent point is determined to transform the robotic arm with a nonhuman-like kinematic structure into an anthropomorphic robotic arm. Based on this equivalent point, a mapping method is developed to ensure that the two arms are similar. Finally, the similarity between the human elbow angle and robot elbow angle is further improved by using this method and an augmented Jacobian matrix with a compensation coefficient.

Numerical simulations and physical prototype experiments are conducted to verify the effectiveness and feasibility of the proposed method. In environments with obstacles, this method can adjust the position of the equivalent point in real time to avoid obstacles. In environments without obstacles, the similarity between the human elbow angle and robot elbow angle is further improved at the expense of the end-effector accuracy.

This study presents a new kinematics mapping method, which can realize the complete mapping between the human arm and heterogeneous robotic arm in teleoperation. This method is versatile and can be applied to various mechanical arms with different structures.

This paper aims to describe bridge transported servo‐manipulator (BTSM) system, which was developed to overcome the limited workspace of the conventional mechanical master‐slave manipulators in a hot cell.

The BTSM system consists of four components: a transporter with a telescoping tubeset, a slave manipulator, a master manipulator, and a remote control system. The slave manipulator is able to move horizontally, transversely, and vertically by using the transporter.

The performance test of the BTSM system has been carried out in terms of basic functions such as force threshold, bilateral control and force reflection characteristic.

With respect to design characteristic, the BTSM system has the novel features in that the individual motor modules or the slave manipulator can be repaired in a fully remote manner in case of catastrophic failure. Also, a 3D viewing camera facilitates remote tasks giving human operators realistic environmental information.