Unlimited-wokspace teleoperation

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 100-105)Text in English; Abstract: Turkish and Englishxiv, 109 leavesTeleoperation is, in its brief description, operating a vehicle or a manipulator from a distance. Teleoperation is used to reduce mission cost, protect humans from accidents that can be occurred during the mission, and perform complex missions for tasks that take place in areas which are difficult to reach or dangerous for humans. Teleoperation is divided into two main categories as unilateral and bilateral teleoperation according to information flow. This flow can be configured to be in either one direction (only from master to slave) or two directions (from master to slave and from slave to master). In unlimited-workspace teleoperation, one of the types of bilateral teleoperation, mobile robots are controlled by the operator and environmental information is transferred from the mobile robot to the operator. Teleoperated vehicles can be used in a variety of missions in air, on ground and in water. Therefore, different constructional types of robots can be designed for the different types of missions. This thesis aims to design and develop an unlimited-workspace teleoperation which includes an omnidirectional mobile robot as the slave system to be used in further researches. Initially, an omnidirectional mobile robot was manufactured and robot-operator interaction and efficient data transfer was provided with the established communication line. Wheel velocities were measured in real-time by Hall-effect sensors mounted on robot chassis to be integrated in controllers. A dynamic obstacle detection system, which is suitable for omnidirectional mobility, was developed and two obstacle avoidance algorithms (semi-autonomous and force reflecting) were created and tested. Distance information between the robot and the obstacles was collected by an array of sensors mounted on the robot. In the semi-autonomous teleoperation scenario, distance information is used to avoid obstacles autonomously and in the force-reflecting teleoperation scenario obstacles are informed to the user by sending back the artificially created forces acting on the slave robot. The test results indicate that obstacle avoidance performance of the developed vehicle with two algorithms is acceptable in all test scenarios. In addition, two control models were developed (kinematic and dynamic control) for the local controller of the slave robot. Also, kinematic controller was supported by gyroscope

Wheeled Mobile Robots: State of the Art Overview and Kinematic Comparison Among Three Omnidirectional Locomotion Strategies

In the last decades, mobile robotics has become a very interesting research topic in the feld of robotics, mainly because of population ageing and the recent pandemic emergency caused by Covid-19. Against this context, the paper presents an overview on wheeled mobile robot (WMR), which have a central role in nowadays scenario. In particular, the paper describes the most commonly adopted locomotion strategies, perception systems, control architectures and navigation approaches. After having analyzed the state of the art, this paper focuses on the kinematics of three omnidirectional platforms: a four mecanum wheels robot (4WD), a three omni wheel platform (3WD) and a two swerve-drive system (2SWD). Through a dimensionless approach, these three platforms are compared to understand how their mobility is afected by the wheel speed limitations that are present in every practical application. This original comparison has not been already presented by the literature and it can be used to improve our understanding of the kinematics of these mobile robots and to guide the selection of the most appropriate locomotion system according to the specifc application

Design and Control of Robotic Systems for Lower Limb Stroke Rehabilitation

Lower extremity stroke rehabilitation exhausts considerable health care resources, is labor intensive, and provides mostly qualitative metrics of patient recovery. To overcome these issues, robots can assist patients in physically manipulating their affected limb and measure the output motion. The robots that have been currently designed, however, provide assistance over a limited set of training motions, are not portable for in-home and in-clinic use, have high cost and may not provide sufficient safety or performance. This thesis proposes the idea of incorporating a mobile drive base into lower extremity rehabilitation robots to create a portable, inherently safe system that provides assistance over a wide range of training motions. A set of rehabilitative motion tasks were established and a six-degree-of-freedom (DOF) motion and force-sensing system was designed to meet high-power, large workspace, and affordability requirements. An admittance controller was implemented, and the feasibility of using this portable, low-cost system for movement assistance was shown through tests on a healthy individual. An improved version of the robot was then developed that added torque sensing and known joint elasticity for use in future clinical testing with a flexible-joint impedance controller

Contemporary Robotics

This book book is a collection of 18 chapters written by internationally recognized experts and well-known professionals of the field. Chapters contribute to diverse facets of contemporary robotics and autonomous systems. The volume is organized in four thematic parts according to the main subjects, regarding the recent advances in the contemporary robotics. The first thematic topics of the book are devoted to the theoretical issues. This includes development of algorithms for automatic trajectory generation using redudancy resolution scheme, intelligent algorithms for robotic grasping, modelling approach for reactive mode handling of flexible manufacturing and design of an advanced controller for robot manipulators. The second part of the book deals with different aspects of robot calibration and sensing. This includes a geometric and treshold calibration of a multiple robotic line-vision system, robot-based inline 2D/3D quality monitoring using picture-giving and laser triangulation, and a study on prospective polymer composite materials for flexible tactile sensors. The third part addresses issues of mobile robots and multi-agent systems, including SLAM of mobile robots based on fusion of odometry and visual data, configuration of a localization system by a team of mobile robots, development of generic real-time motion controller for differential mobile robots, control of fuel cells of mobile robots, modelling of omni-directional wheeled-based robots, building of hunter- hybrid tracking environment, as well as design of a cooperative control in distributed population-based multi-agent approach. The fourth part presents recent approaches and results in humanoid and bioinspirative robotics. It deals with design of adaptive control of anthropomorphic biped gait, building of dynamic-based simulation for humanoid robot walking, building controller for perceptual motor control dynamics of humans and biomimetic approach to control mechatronic structure using smart materials

Lunar Rover with Multiple Science Handling Capability

A rover design study was undertaken for exploration of the Moon. Rovers that have been launched in the past carried a suite of science payload either onboard its body or on the robotic arm’s end. No rover has so far been launched and tasked with “carrying and deploying” a payload on an extraterrestrial surface. This paper describes a lunar rover designed for deploying payload as well as carrying a suite of instruments onboard for conventional science tasks. The main consideration during the rover design process was the usage of existing, in-house technology for development of some rover systems. The manipulation subsystem design was derived from the technology of Light Weight Robot, a dexterous arm originally developed for terrestrial applications. Recent efforts have led to definition of a mission architecture for exploration of the Moon with such a rover. An outline of its design, the manipulating arm technology and the design decisions that were made has been presented

Motion Control of Holonomic Wheeled Mobile Robot with Modular Actuation

This thesis proposes a control scheme for a new holonomic wheeled mobile robot. The platform, which is called C3P (Caster 3 wheels Platform), is designed and built by the Automation Lab., University of Heidelberg. The platform has three driven caster wheels, which are used because of their simple construction and easy maintenance. The C3P has modular actuators and sensors configurations. The robot’s actuation scheme produces singularity difficulties for some wheel steering configuration, described as the following: When all wheels yield the same steering angle value, the C3P cannot be actuated in the direction perpendicular to the wheel velocity vector. The C3P has a modular sensing scheme defined by sensing the steering angle and the wheel angular velocity of each caster wheel. This work has four main contributions 1- developing a controller based on an inverse kinematics solution to handle motion commands in the singular configurations; 2- modeling the C3P’s forward dynamics of the C3P for the simulation purpose; 3- developing a motion controller based on an inverse dynamics solution; and 4- comparing the C3P with other standard holonomic WMRs. In order to escape singularity condition, the actuated inverse kinematics solution is developed based on the idea of coupling any two wheel velocities to virtually actuate the steering angular velocity of the third wheel. The solution is termed as the Wheel Coupling Equation (WCE). The C3P velocity controller consists of two parts: a) the WCE regulator to avoid singularities and adjust the steering angles to the desired value, and b) the regular PID controller to maintain the reference robot velocities with respect to the floor frame of coordinates. The solution reaches acceptable performance in the simulation examples and in the practical experiments. However, it generates relatively large displacement errors only during the steering angles adjustment period. The Euler-Lagrangian method is used for obtaining the forward dynamic and the inverse dynamic models. The forward dynamic model consists of two equations of motion: the WTD (Wheel Torque Dynamics) to calculate the wheel angular velocities with respect to the actuated wheels’ torques, and the DSE (Dynamic Steering Estimator) for calculating the steering angles and steering angular velocities corresponding to the angular wheels’ velocities and accelerations. The inverse dynamics solution defines the forces and torques acting on each actuator and joint. The solution is used in the development of the C3P velocity and position controllers. In comparison to the proposed inverse kinematics solution, the inverse dynamics solution yields less displacement errors. Lyapunov stability analysis is carried out to investigate the system stability for different steering angles’ combinations. The steering angles’ values are considered as the disturbances affecting the platform. Finally, a comparison is made between the C3P and three other holonomic wheeled mobile robots configurations. The comparison is based on the simulation results in relation to the following aspects: a) mobility, b) total energy consumed by each robot in a finite interval of time and c) hardware complexity. The C3P platform shows its advantage in the aspects “b” and “c”

Kinematic and dynamic analysis of mobile robot

Master'sMASTER OF SCIENC