Controlling swimming and crawling in a fish robot using a central pattern generator

Online trajectory generation for robots with multiple degrees of freedom is still a difficult and unsolved problem, in particular for non-steady state locomotion, that is, when the robot has to move in a complex environment with continuous variations of the speed, direction, and type of locomotor behavior. In this article we address the problem of controlling the non-steady state swimming and crawling of a novel fish robot. For this, we have designed a control architecture based on a central pattern generator (CPG) implemented as a system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. To test our controller, we designed BoxyBot, a simple fish robot with three actuated fins capable of swimming in water and crawling on firm ground. Using the CPG model, the robot is capable of performing and switching between a variety of different locomotor behaviors such as swimming forwards, swimming backwards, turning, rolling, moving upwards/downwards, and crawling. These behaviors are triggered and modulated by sensory input provided by light, water, and touch sensors. Results are presented demonstrating the agility of the robot and interesting properties of a CPG-based control approach such as stability of the rhythmic patterns due to limit cycle behavior, and the production of smooth trajectories despite abrupt changes of control parameters. The robot is currently used in a temporary 20-month long exhibition at the EPFL. We present the hardware setup that was designed for the exhibition, and the type of interactions with the control system that allow visitors to influence the behavior of the robot. The exhibition is useful to test the robustness of the robot for long term use, and to demonstrate the suitability of the CPG-based approach for interactive control with a human in the loop. This article is an extended version of an article presented at BioRob2006 the first IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronic

Controlling swimming and crawling in a fish robot using a central pattern generator

Online trajectory generation for robots with multiple degrees of freedom is still a difficult and unsolved problem, in particular for non-steady state locomotion, that is, when the robot has to move in a complex environment with continuous variations of the speed, direction, and type of locomotor behavior. In this article we address the problem of controlling the non-steady state swimming and crawling of a novel fish robot. For this, we have designed a control architecture based on a central pattern generator (CPG) implemented as a system of coupled nonlinear oscillators. The CPG, like its biological counterpart, can produce coordinated patterns of rhythmic activity while being modulated by simple control parameters. To test our controller, we designed BoxyBot, a simple fish robot with three actuated fins capable of swimming in water and crawling on firm ground. Using the CPG model, the robot is capable of performing and switching between a variety of different locomotor behaviors such as swimming forwards, swimming backwards, turning, rolling, moving upwards/downwards, and crawling. These behaviors are triggered and modulated by sensory input provided by light, water, and touch sensors. Results are presented demonstrating the agility of the robot and interesting properties of a CPG-based control approach such as stability of the rhythmic patterns due to limit cycle behavior, and the production of smooth trajectories despite abrupt changes of control parameters. The robot is currently used in a temporary 20-month long exhibition at the EPFL. We present the hardware setup that was designed for the exhibition, and the type of interactions with the control system that allow visitors to influence the behavior of the robot. The exhibition is useful to test the robustness of the robot for long term use, and to demonstrate the suitability of the CPG-based approach for interactive control with a human in the loop. This article is an extended version of an article presented at BioRob2006 the first IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics

Antarctica rover design and optimization for limited power consumption

The design process of the new locomotion platform called K11 aims at obtaining a rover capable of traveling thousands of kilometers at 1 m/s in the harsh environment of Antarctica during summer and carrying a 100 kg payload. A model including the drive-train power consumption and masses is used to optimize the parameters of the rover in order to minimize the power consumption. The obtained configuration consumes theoretically only 58W on flat ground and has limited power consumption while climbing a slope. The prototype built based on the optimization results is used to confirm the model.ISSN:1474-667

ERGO:A FRAMEWORK FOR THE DEVELOPMENT OF AUTONOMOUS ROBOTS

The European Robotic Goal-Oriented Autonomous Controller ERGO (http://www.h2020-ergo.eu/) is one of the six space robotic projects in the frame of the PERASPERA SRC (http://www.h2020-peraspera.eu/). Its goal is to provide an Autonomy Framework capable of operating at different levels of autonomy, from teleoperations to full on-board autonomy. Even though it has been originally conceived for space robotics, its domain independent design facilitates its application to any terrestrial robotic system.  This paper presents the approach followed, current status and future steps

Design concepts and implementation of the Lightweight Advanced Robotic Arm Demonstrator (LARAD)

Beyond the current ExoMars programme, the European Space Agency (ESA) is investigating a range of technology developments and exploration mission opportunities leading to a future Mars Sample Return Mission (MSR), a critical next in the exploration of Mars. To fulfil their scientific objectives, all of these missions require an arm with a long reach capable of performing a variety of tasks in stringent environmental conditions, such as low gravity sampling and precise sample handling and insertion. As part of a CREST-2 project supported by the UK Space Agency (UKSA), a consortium of UK companies have co-founded and developed LARAD, a new Lightweight Advanced Robotic Arm Demonstrator to address some of the underlying challenges related both to the design as well as operation of long arms to perform the payload deployment and sample return operations of future missions. The 15kg terrestrial demonstrator is built as a 2m long arm with 6 degrees of freedom. This arm is capable of deploying a payload with a mass up to 6kgs or operating a 4kg end-effector at 2m. It is using cutting edge technologies on both the hardware and software levels. The mechanical structure of the arm has been manufactured using an array of new processes such as optimised 3D printed titanium Additive Layer Manufactured (ALM) joints, Titanium/Silicon carbide metallic composites, and 3D printed harness routing drums. A modular joint design has been produced, featuring three mechanical sizes of joints each with integrated low level communication and motor drive. The electronics, software and sensors used in the joints are common across all sizes, increasing modularity. To achieve precise positioning, very high resolution absolute position sensing is used on-board. The arm uses novel collision avoidance and path-planning strategies combined with classical control loops. The On-board Control System?s state machine combines different control strategies/modes (i.e. joint trajectory tracking, direct motor control, autonomous placement) depending on the high level user operation requirements. The high level On Board Computer (OBC) is Robot Operating System (ROS) based, enabling a flexible software approach. This project will provide a unique and representative platform to plan and rehearse science operations with full mass payload and instruments, unlike typical planetary arm developments that require scaled-mass end-effector. This paper describes the current state-of-the-art in planetary robotics and provides an overview of the top-level architecture, implementation and laboratory testing phases for the LARAD robotic arm.Peer reviewe