Design and Control of Compliant Tensegrity Robots Through Simulation and Hardware Validation

To better understand the role of tensegrity structures in biological systems and their application to robotics, the Dynamic Tensegrity Robotics Lab at NASA Ames Research Center has developed and validated two different software environments for the analysis, simulation, and design of tensegrity robots. These tools, along with new control methodologies and the modular hardware components developed to validate them, are presented as a system for the design of actuated tensegrity structures. As evidenced from their appearance in many biological systems, tensegrity ("tensile-integrity") structures have unique physical properties which make them ideal for interaction with uncertain environments. Yet these characteristics, such as variable structural compliance, and global multi-path load distribution through the tension network, make design and control of bio-inspired tensegrity robots extremely challenging. This work presents the progress in using these two tools in tackling the design and control challenges. The results of this analysis includes multiple novel control approaches for mobility and terrain interaction of spherical tensegrity structures. The current hardware prototype of a six-bar tensegrity, code-named ReCTeR, is presented in the context of this validation

Open Source VSA-CubeBots for Rapid Soft Robot Prototyping

Nowadays, rapid robot prototyping is a desired capability of any robotics laboratory. Combining the speed of 3D plastic printing and the use of custom Open Source electronic hardware/software solutions, our laboratory successfully developed and used tools related to variable impedance robot technology. This paper describes how we capitalized the design and use of one kind of variable stiffness actuators as a modular tool to prototype and test in a quick fashion several robot capabilities. The extension of such a modular tool for rapid prototyping allowed us to use it in several applications and scenarios, including the educational setting, aiming to speed up the gap between theory and practice in robotics. The complete palette of developments of our laboratory in hardware/software as well as some robotic systems applications shown here, are open source and contribute to the Natural Motion Initiative

Behavior Trees in Robotics and AI: An Introduction

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

The CLAWAR project

In Europe, there are two main thematic groups focusing on robotics, the Climbing and Walking Robots (CLAWAR) project (http://www.clawar.net) and the European Robotics Network (EURON) project (http://www.euron.org). The two networks are complementary: CLAWAR is industrially focused on the immediate needs, and EURON is focused more on blue skies research. This article presents the activities of the CLAWAR project

The CLAWAR project

In Europe, there are two main thematic groups focusing on robotics, the Climbing and Walking Robots (CLAWAR) project (http://www.clawar.net) and the European Robotics Network (EURON) project (http://www.euron.org). The two networks are complementary: CLAWAR is industrially focused on the immediate needs, and EURON is focused more on blue skies research. This article presents the activities of the CLAWAR project

Bio-inspired Tensegrity Soft Modular Robots

In this paper, we introduce a design principle to develop novel soft modular robots based on tensegrity structures and inspired by the cytoskeleton of living cells. We describe a novel strategy to realize tensegrity structures using planar manufacturing techniques, such as 3D printing. We use this strategy to develop icosahedron tensegrity structures with programmable variable stiffness that can deform in a three-dimensional space. We also describe a tendon-driven contraction mechanism to actively control the deformation of the tensegrity mod-ules. Finally, we validate the approach in a modular locomotory worm as a proof of concept.Comment: 12 pages, 7 figures, submitted to Living Machine conference 201

AltURI: a thin middleware for simulated robot vision applications

Fast software performance is often the focus when developing real-time vision-based control applications for robot simulators. In this paper we have developed a thin, high performance middleware for USARSim and other simulators designed for real-time vision-based control applications. It includes a fast image server providing images in OpenCV, Matlab or web formats and a simple command/sensor processor. The interface has been tested in USARSim with an Unmanned Aerial Vehicle using two control applications; landing using a reinforcement learning algorithm and altitude control using elementary motion detection. The middleware has been found to be fast enough to control the flying robot as well as very easy to set up and use