2,639 research outputs found

    Design and Experiments with a Low-Cost Single-Motor Modular Aquatic Robot

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    We present a novel design for a low-cost robotic boat powered by a single actuator, useful for both modular and swarming applications. The boat uses the conservation of angular momentum and passive flippers to convert the motion of a single motor into an adjustable paddling motion for propulsion and steering. We develop design criteria for modularity and swarming and present a prototype implementing these criteria. We identify significant mechanical sensitivities with the presented design, theorize about the cause of the sensitivities, and present an improved design for future work.Comment: Accepted to the International Conference on Ubiquitous Robots (UR 2020). 8 page

    Actuators for a space manipulator

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    The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator

    Behavior Trees in Robotics and AI: An Introduction

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    A Behavior Tree (BT) is a way to structure the switching between different tasks in an autonomous agent, such as a robot or a virtual entity in a computer game. BTs are a very efficient way of creating complex systems that are both modular and reactive. These properties are crucial in many applications, which has led to the spread of BT from computer game programming to many branches of AI and Robotics. In this book, we will first give an introduction to BTs, then we describe how BTs relate to, and in many cases generalize, earlier switching structures. These ideas are then used as a foundation for a set of efficient and easy to use design principles. Properties such as safety, robustness, and efficiency are important for an autonomous system, and we describe a set of tools for formally analyzing these using a state space description of BTs. With the new analysis tools, we can formalize the descriptions of how BTs generalize earlier approaches. We also show the use of BTs in automated planning and machine learning. Finally, we describe an extended set of tools to capture the behavior of Stochastic BTs, where the outcomes of actions are described by probabilities. These tools enable the computation of both success probabilities and time to completion

    Pneumatic motion control systems for modular robots

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    This thesis describes a research study in the design, implementation, evaluation and commercialisation of pneumatic motion control systems for modular robots. The research programme was conducted as part of a collaborative study, sponsored by the Science and Engineering Research Council, between Loughborough University and Martonair (UK) Limited. Microprocessor based motion control strategies have been used to produce low cost pneumatic servo-drives which can be used for 'point-to-point' positioning of payloads. Software based realtime control strategies have evolved which accomplish servo-controlled positioning while compensating for drive system non-linearities and time delays. The application of novel compensation techniques has resulted in a significant improvement in both the static and dynamic performance of the drive. A theoretical foundation is presented based on a linearised model of a pneumatic actuator, servo-valve, and load system. The thesis describes the design and evolution of microprocessor based hardware and software for motion control of pneumatic drives. A British Standards based test-facility has allowed control strategies to be evaluated with reference to standard performance criteria. It is demonstrated in this research study that the dynamic and static performance characteristics of a pneumatic motion control system can be dramatically improved by applying appropriate software based realtime control strategies. This makes the application of computer controlled pneumatic servos in manufacturing very attractive with cost performance ratios which match or better alternative drive technologies. The research study has led to commercial products (marketed by Martonair Ltd), in which realtime control algorithms implementing these control strategy designs are executed within a microprocessor based motion controller

    Torque Auditing Test Fixture for Hansen Medical’s Remote Catheter Manipulator Robot

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    Current manufacturing test systems for motor control of Hansen\u27s line of surgical robots are labor intensive, have room for operator error and do not supply sufficient information. Based upon an expected increase in production, the objective of this project was to replace their test protocol with a modular test fixture that improves test time, is intuitive to use, and enhances the user experience. We developed a modular design that works for both the Sensei and Magellan robots, and can be reconfigured easily for use on future robots. Using a control system and GUI made in LabVIEW, a magnetic particle as our torque actuator, and a Futek rotary torque sensor for precise data acquisition, our device is a creative, efficient, and effective replacement to Hansen’s quality testing. We successfully develop an equivalent test, surpassed our goal of decreasing test time, our fixture is completely modular for all Hansen’s RCMs, we integrated two tests into a single operation, and we received favorable feedback from the engineers and technicians whom proposed this project. This project succeeded in creating a functional prototype to replace Hansen Medical’s current test protocol. Our test system has been handed off to Hansen Medical for implementation and further development

    An 8-DOF dual-arm system for advanced teleoperation performance experiments

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    This paper describes the electro-mechanical and control features of an 8-DOF manipulator manufactured by AAI Corporation and installed at the Jet Propulsion Lab. (JPL) in a dual-arm setting. The 8-DOF arm incorporates a variety of features not found in other lab or industrial manipulators. Some of the unique features are: 8-DOF revolute configuration with no lateral offsets at joint axes; 1 to 5 payload to weight ratio with 20 kg (44 lb) payload at a 1.75 m (68.5 in.) reach; joint position measurement with dual relative encoders and potentiometer; infinite roll of joint 8 with electrical and fiber optic slip rings; internal fiber optic link of 'smart' end effectors; four-axis wrist; graphite epoxy links; high link and joint stiffness; use of an upgraded JPL Universal Motor Controller (UMC) capable of driving up to 16 joints. The 8-DOF arm is equipped with a 'smart' end effector which incorporates a 6-DOF forcemoment sensor at the end effector base and grasp force sensors at the base of the parallel jaws. The 8-DOF arm is interfaced to a 6 DOF force reflecting hand controller. The same system is duplicated for and installed at NASA-Langley

    An analysis of the effect of gravitational load on the energy consumption of industrial robots

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    The gravitational load has a great impact on industrial robots’ torque. Much research has gone into investigating this parameter in order to find an effective solution for achieving high performance of the robot systems. However, the existing investigations are still limited to analyze the influence of the gravitational load on the robot torque behavior. An analysis of the direct influence of gravitational load on electrical energy consumption has not yet been explored. This paper provides a model based approach for analyzing the effect of the gravitational load to the energy consumption. A mechatronic simulation tool is used for analyzing robot energy consumption. The results show that the gravitational load has an influence on the energy consumption of high-mass industrial robots, especially during upward movement
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