Collision avoidance and dynamic modeling for wheeled mobile robots and industrial manipulators

Collision Avoidance and Dynamic Modeling are key topics for researchers dealing with mobile and industrial robotics. A wide variety of algorithms, approaches and methodologies have been exploited, designed or adapted to tackle the problems of finding safe trajectories for mobile robots and industrial manipulators, and of calculating reliable dynamics models able to capture expected and possible also unexpected behaviors of robots. The knowledge of these two aspects and their potential is important to ensure the efficient and correct functioning of Industry 4.0 plants such as automated warehouses, autonomous surveillance systems and assembly lines. Collision avoidance is a crucial aspect to improve automation and safety, and to solve the problem of planning collision-free trajectories in systems composed of multiple autonomous agents such as unmanned mobile robots and manipulators with several degrees of freedom. A rigorous and accurate model explaining the dynamics of robots, is necessary to tackle tasks such as simulation, torque estimation, reduction of mechanical vibrations and design of control law

Robot Manipulators

Robot manipulators are developing more in the direction of industrial robots than of human workers. Recently, the applications of robot manipulators are spreading their focus, for example Da Vinci as a medical robot, ASIMO as a humanoid robot and so on. There are many research topics within the field of robot manipulators, e.g. motion planning, cooperation with a human, and fusion with external sensors like vision, haptic and force, etc. Moreover, these include both technical problems in the industry and theoretical problems in the academic fields. This book is a collection of papers presenting the latest research issues from around the world

Industrial Robotics

This book covers a wide range of topics relating to advanced industrial robotics, sensors and automation technologies. Although being highly technical and complex in nature, the papers presented in this book represent some of the latest cutting edge technologies and advancements in industrial robotics technology. This book covers topics such as networking, properties of manipulators, forward and inverse robot arm kinematics, motion path-planning, machine vision and many other practical topics too numerous to list here. The authors and editor of this book wish to inspire people, especially young ones, to get involved with robotic and mechatronic engineering technology and to develop new and exciting practical applications, perhaps using the ideas and concepts presented herein

Task-space dynamic control of underwater robots

This thesis is concerned with the control aspects for underwater tasks performed by marine robots. The mathematical models of an underwater vehicle and an underwater vehicle with an onboard manipulator are discussed together with their associated properties. The task-space regulation problem for an underwater vehicle is addressed where the desired target is commonly specified as a point. A new control technique is proposed where the multiple targets are defined as sub-regions. A fuzzy technique is used to handle these multiple sub-region criteria effectively. Due to the unknown gravitational and buoyancy forces, an adaptive term is adopted in the proposed controller. An extension to a region boundary-based control law is then proposed for an underwater vehicle to illustrate the flexibility of the region reaching concept. In this novel controller, a desired target is defined as a boundary instead of a point or region. For a mapping of the uncertain restoring forces, a least-squares estimation algorithm and the inverse Jacobian matrix are utilised in the adaptive control law. To realise a new tracking control concept for a kinematically redundant robot, subregion tracking control schemes with a sub-tasks objective are developed for a UVMS. In this concept, the desired objective is specified as a moving sub-region instead of a trajectory. In addition, due to the system being kinematically redundant, the controller also enables the use of self-motion of the system to perform sub-tasks (drag minimisation, obstacle avoidance, manipulability and avoidance of mechanical joint limits)

Open-loop position control in collaborative, modular Variable-Stiffness-Link (VSL) robots

— Collaborative robots (cobots) open up new avenues in the fields of industrial robotics and physical Human-Robot Interaction (pHRI) as they are suitable to work in close approximation and in collaboration with humans. The integration and control of variable stiffness elements allow inherently safe interaction. Apart from notable work on Variable Stiffness Actuators, the concept of Variable-Stiffness-Link (VSL) manipulators promises safety improvements in cases of unintentional physical collisions. However, position control of these type of robotic manipulators is challenging for critical task-oriented motions (e.g., pick and place). Hence, the study of open-loop position control for VSL robots is crucial to achieve high levels of safety, accuracy and hardware cost-efficiency in pHRI applications. In this paper, we propose a hybrid, learning based kinematic modelling approach to improve the performance of traditional open-loop position controllers for a modular, collaborative VSL robot. We show that our approach improves the performance of traditional open-loop position controllers for robots with VSL and compensates for position errors, in particular, for lower stiffness values inside the links: Using our upgraded and modular robot, two experiments have been carried out to evaluate the behaviour of the robot during taskoriented motions. Results show that traditional model-based kinematics are not able to accurately control the position of the end-effector: the position error increases with higher loads and lower pressures inside the VSLs. On the other hand, we demonstrate that, using our approach, the VSL robot can outperform the position control compared to a robotic manipulator with 3D printed rigid links

The Development of a Multi-arm Mobile Robot System for Nuclear Decommissioning Applications.

This PhD thesis is based in the field of robotics and introduces a case study of the design and development of a multi-arm mobile robot system for nuclear decommissioning (MARS-ND). A key premise underlying the research was to develop intelligence in the robot that is similar to the cooperation and communication between the human brain and its two arms; hence the human body was adopted as the starting point to establish the size and functionality of the proposed system. The approach adopted for this research demonstrates the development, integration and configuration of a multi-arm robot system which consists of two human armlike off-the-shelf manipulators whose joints are controlled using potentiometer sensors and hydraulic actuators. Using the manipulators' sensor feedback, a wide variety of complex tasks found in the rapidly expanding field of nuclear decommissioning can be undertaken. The thesis also considers the issue of collaboration, collision detection and collision avoidance between the two arms of MARS-ND. As part of the final stage of this research the author participated in a collaborative research project with the Sugano Laboratory at Waseda University, Tokyo, Japan. The three major research issues addressed in this thesis are: 1. The selection and integration of off-the-shelf hardware in the development of MARS-ND using the latest technology available for robotic systems 2. The creation of a suitable control system for the robot arms; and the building of an advanced, user-friendly interface between the robot system and the host computer 3. The investigation and implementation of collaboration, coordinated motion control and collision detection & avoidance techniques for the robot arms The hardware and software integration for the whole robotic system is explained with the proposed software architecture and the use of National Instruments (NI) functions and tools to control the movement of the arm joints and the performance of a selected decommissioning task. This thesis also examines the operational software applied within the research through its discussion of four interlinked areas: 1. The control software and hardware interface for the MARS-ND and the controller architecture 2. The application of an NI Compact FieldPoint controller and FieldPoint I/O modules to facilitate wireless communication between the Multi-Arm Mobile Robot system and the user interface in the host PC 3. The use of Measurement and Automation Explorer (MAX) and LabVIEW software tools for calibration and the building of user interfaces required for sending and receiving the signals needed to control the robot arm joints accurately 4. The application of a PID toolkit in LabVIEW for the design of a simple PID controller for the individual arm joints with a potentiometer sensor fitted inside each joint in order to provide a feedback signal to the controller The thesis concludes that MARS-ND is a good example of a robotic system specifically designed for hazardous nuclear decommissioning applications. It demonstrates the complexity of such a system from a number of aspects such as the need for mobility, control, sensor and system design, and integration using modem tools that are available off-the-shelf. In addition the use of these modern tools allows a single mechatronics engineer to design, integrate, interface and build a motion control system for MARS-ND as compared to the traditional way of building a similar robot by a team of specialised engineers. The contribution this research makes to the design and building of multi-arm robot system for nuclear decommissioning industry concerns its size and mobility using a mobile platform to transport the multi-arm robot system. In addition links have been made between Lancaster University and Waseda University in the context of the development of multi-arm robot systems

Modeling and Control of Flexible Link Manipulators

Autonomous maritime navigation and offshore operations have gained wide attention with the aim of reducing operational costs and increasing reliability and safety. Offshore operations, such as wind farm inspection, sea farm cleaning, and ship mooring, could be carried out autonomously or semi-autonomously by mounting one or more long-reach robots on the ship/vessel. In addition to offshore applications, long-reach manipulators can be used in many other engineering applications such as construction automation, aerospace industry, and space research. Some applications require the design of long and slender mechanical structures, which possess some degrees of flexibility and deflections because of the material used and the length of the links. The link elasticity causes deflection leading to problems in precise position control of the end-effector. So, it is necessary to compensate for the deflection of the long-reach arm to fully utilize the long-reach lightweight flexible manipulators. This thesis aims at presenting a unified understanding of modeling, control, and application of long-reach flexible manipulators. State-of-the-art dynamic modeling techniques and control schemes of the flexible link manipulators (FLMs) are discussed along with their merits, limitations, and challenges. The kinematics and dynamics of a planar multi-link flexible manipulator are presented. The effects of robot configuration and payload on the mode shapes and eigenfrequencies of the flexible links are discussed. A method to estimate and compensate for the static deflection of the multi-link flexible manipulators under gravity is proposed and experimentally validated. The redundant degree of freedom of the planar multi-link flexible manipulator is exploited to minimize vibrations. The application of a long-reach arm in autonomous mooring operation based on sensor fusion using camera and light detection and ranging (LiDAR) data is proposed.publishedVersio

Research on a semiautonomous mobile robot for loosely structured environments focused on transporting mail trolleys

In this thesis is presented a novel approach to model, control, and planning the motion of a nonholonomic wheeled mobile robot that applies stable pushes and pulls to a nonholonomic cart (York mail trolley) in a loosely structured environment. The method is based on grasping and ungrasping the nonholonomic cart, as a result, the robot changes its kinematics properties. In consequence, two robot configurations are produced by the task of grasping and ungrasping the load, they are: the single-robot configuration and the robot-trolley configuration. Furthermore, in order to comply with the general planar motion law of rigid bodies and the kinematic constraints imposed by the robot wheels for each configuration, the robot has been provided with two motorized steerable wheels in order to have a flexible platform able to adapt to these restrictions. [Continues.