{Development of a mobile manipulator robot kit for educational purposes

This thesis focuses on designing, building, and developing a prototype of a mobile robot base for a manipulator mobile robot using the Robot Operating System (ROS) 2 as a part of a larger project conducted by the mechatronics department at the University of Agder. This thesis has four main goals: 1) Design an affordable mobile robot base that fits the uArm manipulator. 2) Develop the required ROS2 packages for the selected hardware components in order to perform mobile robot localization, mapping, and autonomous navigation using the SLAM toolbox and Nav2 framework. 3) Construct a prototype of the designed mobile robot base. 4) Test the developed ROS2 packages by performing autonomous navigation in a dynamic environment. The test results showed that the Uiabot prototype succeeded in building a 2D representation of the environment, navigating successfully in this dynamic environment, and avoiding static and dynamic objects

Automatic State Estimation of an Over-Sensored Robotic Manipulator

Há uma procura cada vez maior por manipuladores robóticos capazes de efetuar atividades complexas e versáteis. De modo a satisfazer essa necessidade, é essencial a implementação de técnicas de calibração e estimação expeditas como um primeiro passo para o correto uso do manipulador. Só após a resolução destes problemas é que se torna possível usar o manipulador para efetuar tarefas de mais alto nível, tais como posicionamento de uma ferramenta ou manipulação de objetos. Existem atualmente várias técnicas de calibração automática para uma larga gama de sensores, assim como vários filtros capazes da fusão das suas medidas. Esta dissertação tem como objetivo encontrar e implementar um conjunto destes algoritmos capazes de ser usados num manipulador genérico. As técnicas escolhidas são modulares, o que torna possível a sua utilização em diferentes configurações de manipuladores. Os requisitos para a sua utilização foram restringidos tanto quanto possível de modo a serem reutilizáveis por quem tem limitações a nível de equipamento. Um manipulador robótico previamente desenvolvido é usado como base para a implementação e teste dos diferentes métodos. Este está equipado com encoders incrementais, IMUs e células de carga. Um conjunto de métodos para a calibração dos sensores inerciais é descrito e as medidas calibradas são usadas em conjunto com as medidas dos encoders para determinar a pose do manipulador. São descritos dois modelos para a representação da pose do manipulador, os quais são usados no problema de estimação de estado. Um deles define o estado como a dinâmica dos ângulos de cada articulação. O outro usa a orientação de cada ligação do manipulador no espaço inercial. O estado do primeiro modelo é estimado usando o Unscented Kalman Filter e o segundo usando o Multiplicative Extended Kalman Filter. Os resultados da implementação são testados e métricas da performance dos métodos são obtidos usando o output dos algoritmos e um sistema de medição externo.There is an increasing demand of robotic manipulators for performing more complex and versatile tasks. In order to fulfill this need, expeditious calibration and estimation techniques are required as a first step for the correct usage of the manipulator. Only after these problems are solved, can it be used for higher level tasks such as generic tool placement and object manipulation. There are currently several techniques for automatic calibration of a wide variety of sensors, as well as several filters to fuse their data into useful information. This dissertation aims at finding a subset of these algorithms that could be used in a generic manipulator and should allow for its prompt use. The techniques used were chosen with the purpose of being modular and therefore usable in a wide variety of manipulators. They also assume a minimal amount of requirements necessary for their use, making them suitable for an unequipped user. A previously developed manipulator is used to realistically test the performance of the implemented methods. It is equipped with incremental encoders, inertial measurement units and load cells. A calibration methodology for the inertial sensors is described and the calibrated measurements are used together with the encoders' to determine the pose of the manipulator. Two models for the representation of the pose of the manipulator are described and used in the state estimation problem. One defines the state vector as the dynamics of the angles of each joint. The other uses the orientation of each link in an inertial frame independently. The state of the first model is estimated with the Unscented Kalman Filter and the second one with the Multiplicative Extended Kalman Filter. The results of implementation are tested and some performance metrics are obtained using both the algorithms' output and an external system

Experimental Apparatus for Vibration Analysis in Robotics

Robotic systems use different types of sensors both in control and in environment perception. Those sensors can be digital encoders, tachometers, accelerometers, force sensors,current sensors and many others. In this paper an experimental setup is presented to study vibrations and impacts. The system acquires data from the sensors, in real time, and, in a second phase, processes it through an analysis package. Several examples with experimental results are carried out showing the functionalities of the developed apparatus.N/

A Methodology of Orthopaedic Measurement Arm Workspace Determination.

This paper outlines general assumptions of work principle of displacement measuring arm that bases on accelerometers. Symbolic representation of arm’s kinematic structure is shown. Also, an analysis of construction correctness has been verified in terms of the effectiveness of using accelerometers to measure individual links displacements. A method of acquiring information on workspace is presented. The workspace has been determined in two variants: without considering last link orientation and for given orientation of that link. Paper also describes a determination method of increments values of angular displacements for individual links of the arm in terms of obtained proper results and rational computation time of workspace scanning algorithm. Finally, there is a presentation of method for determining a cuboid space for arm accuracy and repeatability measurement in XYZ coordinate system

Collaborative human-machine interfaces for mobile manipulators.

The use of mobile manipulators in service industries as both agents in physical Human Robot Interaction (pHRI) and for social interactions has been on the increase in recent times due to necessities like compensating for workforce shortages and enabling safer and more efficient operations amongst other reasons. Collaborative robots, or co-bots, are robots that are developed for use with human interaction through direct contact or close proximity in a shared space with the human users. The work presented in this dissertation focuses on the design, implementation and analysis of components for the next-generation collaborative human machine interfaces (CHMI) needed for mobile manipulator co-bots that can be used in various service industries. The particular components of these CHMI\u27s that are considered in this dissertation include: Robot Control: A Neuroadaptive Controller (NAC)-based admittance control strategy for pHRI applications with a co-bot. Robot state estimation: A novel methodology and placement strategy for using arrays of IMUs that can be embedded in robot skin for pose estimation in complex robot mechanisms. User perception of co-bot CHMI\u27s: Evaluation of human perceptions of usefulness and ease of use of a mobile manipulator co-bot in a nursing assistant application scenario. To facilitate advanced control for the Adaptive Robotic Nursing Assistant (ARNA) mobile manipulator co-bot that was designed and developed in our lab, we describe and evaluate an admittance control strategy that features a Neuroadaptive Controller (NAC). The NAC has been specifically formulated for pHRI applications such as patient walking. The controller continuously tunes weights of a neural network to cancel robot non-linearities, including drive train backlash, kinematic or dynamic coupling, variable patient pushing effort, or slope surfaces with unknown inclines. The advantage of our control strategy consists of Lyapunov stability guarantees during interaction, less need for parameter tuning and better performance across a variety of users and operating conditions. We conduct simulations and experiments with 10 users to confirm that the NAC outperforms a classic Proportional-Derivative (PD) joint controller in terms of resulting interaction jerk, user effort, and trajectory tracking error during patient walking. To tackle complex mechanisms of these next-gen robots wherein the use of encoder or other classic pose measuring device is not feasible, we present a study effects of design parameters on methods that use data from Inertial Measurement Units (IMU) in robot skins to provide robot state estimates. These parameters include number of sensors, their placement on the robot, as well as noise properties on the quality of robot pose estimation and its signal-to-noise Ratio (SNR). The results from that study facilitate the creation of robot skin, and in order to enable their use in complex robots, we propose a novel pose estimation method, the Generalized Common Mode Rejection (GCMR) algorithm, for estimation of joint angles in robot chains containing composite joints. The placement study and GCMR are demonstrated using both Gazebo simulation and experiments with a 3-DoF robotic arm containing 2 non-zero link lengths, 1 revolute joint and a 2-DoF composite joint. In addition to yielding insights on the predicted usage of co-bots, the design of control and sensing mechanisms in their CHMI benefits from evaluating the perception of the eventual users of these robots. With co-bots being only increasingly developed and used, there is a need for studies into these user perceptions using existing models that have been used in predicting usage of comparable technology. To this end, we use the Technology Acceptance Model (TAM) to evaluate the CHMI of the ARNA robot in a scenario via analysis of quantitative and questionnaire data collected during experiments with eventual uses. The results from the works conducted in this dissertation demonstrate insightful contributions to the realization of control and sensing systems that are part of CHMI\u27s for next generation co-bots

User needs, benefits and integration of robotic systems in a space station laboratory

The methodology, results and conclusions of the User Needs, Benefits, and Integration Study (UNBIS) of Robotic Systems in the Space Station Microgravity and Materials Processing Facility are summarized. Study goals include the determination of user requirements for robotics within the Space Station, United States Laboratory. Three experiments were selected to determine user needs and to allow detailed investigation of microgravity requirements. A NASTRAN analysis of Space Station response to robotic disturbances, and acceleration measurement of a standard industrial robot (Intelledex Model 660) resulted in selection of two ranges of low gravity manipulation: Level 1 (10-3 to 10-5 G at greater than 1 Hz.) and Level 2 (less than = 10-6 G at 0.1 Hz). This included an evaluation of microstepping methods for controlling stepper motors and concluded that an industrial robot actuator can perform milli-G motion without modification. Relative merits of end-effectors and manipulators were studied in order to determine their ability to perform a range of tasks related to the three low gravity experiments. An Effectivity Rating was established for evaluating these robotic system capabilities. Preliminary interface requirements were determined such that definition of requirements for an orbital flight demonstration experiment may be established

Arduino Based Trainable Robotic Arm

The popular concept of a robot is of a machine that looks and works like a human being. The industry is moving from current state of automation to robotization, to increase productivity and to deliver uniform quality. A trainable robotic arm is proposed in this paper. The robotic arm is implemented based on the teach function of the arduino. The proposed robotic arm is capable of learning different movements and reproduces them as required. The industrial robots of today may need this type of capabilities to meet the increasing needs of the current trends

An intelligent robot for helping astronauts

This paper describes the development status of a prototype supervised intelligent robot for space application for purposes of (1) helping the crew of a spacecraft such as the Space Station with various tasks, such as holding objects and retrieving/replacing tools and other objects from/into storage, and (2) for purposes of retrieving detached objects, such as equipment or crew, that have become separated from their spacecraft. In addition to this set of tasks in this low-Earth-orbiting spacecraft environment, it is argued that certain aspects of the technology can be viewed as generic in approach, thereby offering insight into intelligent robots for other tasks and environments. Candidate software architectures and their key technical issues which enable real work in real environments to be accomplished safely and robustly are addressed. Results of computer simulations of grasping floating objects are presented. Also described are characterization results on the usable reduced gravity environment in an aircraft flying parabola (to simulate weightlessness) and results on hardware performance there. These results show it is feasible to use that environment for evaluative testing of dexterous grasping based on real-time vision of freely rotating and translating objects