In silico case studies of compliant robots: AMARSI deliverable 3.3

In the deliverable 3.2 we presented how the morphological computing ap- proach can significantly facilitate the control strategy in several scenarios, e.g. quadruped locomotion, bipedal locomotion and reaching. In particular, the Kitty experimental platform is an example of the use of morphological computation to allow quadruped locomotion. In this deliverable we continue with the simulation studies on the application of the different morphological computation strategies to control a robotic system

Development of a Fully Instrumented, Resonant Tensegrity Strut

A tensegrity is a structure composed of a series of rigid members connected in static equilibrium by tensile elements. A vibrating tensegrity robot is an underactuated system in which a set of its struts are vibrated at certain frequency combinations to achieve various locomotive gaits. Evolutionary robotics research lead by Professor John Rieffel focuses on exploiting the complex dynamics of tensegrity structures to control locomotion in vibrating tensegrity robots by finding desired gaits using genetic algorithms. A current hypothesis of interest is that the optimal locomotive gaits of a vibrating tensegrity exist at its resonant frequencies. In order to observe this potential phenomenon, a fully instrumented tensegrity strut module capable of actuating the resonant modes of a vibrating tensegrity and observing the dynamics of its individual struts was developed. The strut consists of a laser-cut acrylic base, a custom DC vibration motor, a 6-axis IMU with onboard data collection, and Bluetooth connectivity for wireless control. Single strut vibration was theoretically modeled and validated against the experimentally observed dynamics. The final iteration of this design successfully actuated the resonant modes of the tensegrity and achieved sufficient motion capture capabilities with a sampling rate of 425 Hz. Additionally, experimental testing with the strut revealed a new frequency-locking phenomenon present in the frequency response of the strut’s vibration

Exploring the Behavior Repertoire of a Wireless Vibrationally Actuated Tensegrity Robot

Soft robotics is an emerging field of research due to its potential to explore and operate in unstructured, rugged, and dynamic environments. However, the properties that make soft robots compelling also make them difficult to robustly control. Here at Union, we developed the world’s first wireless soft tensegrity robot. The goal of my thesis is to explore effective and efficient methods to explore the diverse behavior our tensegrity robot. We will achieve that by applying state-of-art machine learning technique and a novelty search algorithm

Super Ball Bot - Structures for Planetary Landing and Exploration

Small, light-weight and low-cost missions will become increasingly important to NASA's exploration goals for our solar system. Ideally teams of dozens or even hundreds of small, collapsable robots, weighing only a few kilograms a piece, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such teams will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing many lightweight conventional robots is difficult with conventional technology. Current robot designs are delicate, requiring combinations of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead we propose to develop a radically different robot based on a "tensegrity" built purely upon tensile and compression elements. These robots can be light-weight, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and are easy to collapse and uncollapse. We believe tensegrity robot technology can play a critical role in future planetary exploration

Hardware Design and Testing of SUPERball, A Modular Tensegrity Robot

We are developing a system of modular, autonomous "tensegrity end-caps" to enable the rapid exploration of untethered tensegrity robot morphologies and functions. By adopting a self-contained modular approach, different end-caps with various capabilities (such as peak torques, or motor speeds), can be easily combined into new tensegrity robots composed of rods, cables, and actuators of different scale (such as in length, mass, peak loads, etc). As a first step in developing this concept, we are in the process of designing and testing the end-caps for SUPERball (Spherical Underactuated Planetary Exploration Robot), a project at the Dynamic Tensegrity Robotics Lab (DTRL) within NASA Ames's Intelligent Robotics Group. This work discusses the evolving design concepts and test results that have gone into the structural, mechanical, and sensing aspects of SUPERball. This representative tensegrity end-cap design supports robust and repeatable untethered mobility tests of the SUPERball, while providing high force, high displacement actuation, with a low-friction, compliant cabling system

Super Ball Bot - Structures for Planetary Landing and Exploration, NIAC Phase 2 Final Report

Small, light-weight and low-cost missions will become increasingly important to NASA's exploration goals. Ideally teams of small, collapsible, light weight robots, will be conveniently packed during launch and would reliably separate and unpack at their destination. Such robots will allow rapid, reliable in-situ exploration of hazardous destination such as Titan, where imprecise terrain knowledge and unstable precipitation cycles make single-robot exploration problematic. Unfortunately landing lightweight conventional robots is difficult with current technology. Current robot designs are delicate, requiring a complex combination of devices such as parachutes, retrorockets and impact balloons to minimize impact forces and to place a robot in a proper orientation. Instead we are developing a radically different robot based on a "tensegrity" structure and built purely with tensile and compression elements. Such robots can be both a landing and a mobility platform allowing for dramatically simpler mission profile and reduced costs. These multi-purpose robots can be light-weight, compactly stored and deployed, absorb strong impacts, are redundant against single-point failures, can recover from different landing orientations and can provide surface mobility. These properties allow for unique mission profiles that can be carried out with low cost and high reliability and which minimizes the inefficient dependance on "use once and discard" mass associated with traditional landing systems. We believe tensegrity robot technology can play a critical role in future planetary exploration

Metamorphic tensegrity structure for pipe inspection

This paper proposes a new concept of metamorphic tensegrity structure for pipe inspection. A new structural deformation technique is developed that can be employed to design a non-complex and lightweight robot or vehicle. This concept is to deform the cross-shaped tensegrity structure by using the cooperation of prismatic actuators (PAs) and passive joints with locking mechanisms called restrictor mechanisms (RMs). Two control levels are designed to control the structural deformation: A high-level controller for motion patterns and low-level controllers to locally control the PA lengths and restrict the cable lengths of four RMs. Experiments show that the proposed deformation technique can deform the shape and size of the tensegrity structures with the aim of creating a new generation of pipe inspection robots