Tensegrity robots excel in tasks requiring extreme levels of deformability and robustness. However, there are challenges in state estimation and payload versatility due to their high number of degrees of freedom and unconventional shape. This paper introduces a modular three-bar tensegrity robot featuring a customizable payload design. Our tensegrity robot employs a novel Quasi-Direct Drive (QDD) cable actuator paired with low-stretch polymer cables to achieve accurate proprioception without the need for external force or torque sensors. The design allows for on-the-fly stiffness tuning for better environment and payload adaptability. In this paper, we present the design, fabrication, assembly, and experimental results of the robot. Experimental data demonstrates the high accuracy cable length estimation (<1% error relative to bar length) and variable stiffness control of the cable actuator up to 7 times the minimum stiffness for self support. The presented tensegrity robot serves as a platform for future advancements in autonomous operation and open-source module design.
This paper presents a new teleoperated spherical tensegrity robot capable of performing locomotion on steep inclined surfaces. With a novel control scheme centered around the simultaneous actuation of multiple cables, the robot demonstrates robust climbing on inclined surfaces in hardware experiments and speeds significantly faster than previous spherical tensegrity models. This robot is an improvement over other iterations in the TT-series and the first tensegrity to achieve reliable locomotion on inclined surfaces of up to 24\degree. We analyze locomotion in simulation and hardware under sin…
Ecole polytechnique fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
Tensegrity structures are lightweight, can undergo large deformations, and have outstanding robustness capabilities. These unique properties inspired roboticists to investigate their use. However, the morphological design, control, assembly, and actuation of tensegrity robots are still difficult tasks. Moreover, the stiffness of tensegrity robots is still an underestimated design parameter. In this article, we propose to use easy to assemble, actuated tensegrity modules and body-brain co-evolution to design soft tensegrity modular robots. Moreover, we prove the importance of tensegrity robots …
Inverse Statics Optimization for Compound Tensegrity Robots
Department of Mechanical Engineering, University of California Berkeley（加州大学伯克利分校机械工程系）；Intelligent Systems Division, NASA Ames Research Center（NASA阿姆斯研究中心智能系统部）
Tensegrity robots, which are composed of compressive elements (rods) and flexible tensile elements (e.g., cables), have a variety of advantages, including flexibility, low weight, and resistance to mechanical impact. Nevertheless, the hybrid soft-rigid nature of these robots also complicates the ability to localize and track their state. This work aims to address what has been recognized as a grand challenge in this domain, i.e., the state estimation of tensegrity robots through a markerless, vision-based method, as well as novel, onboard sensors that can measure the length of the robot's cabl…
There is a surge of research interest in the field of tensegrity robotics. Robots developed under this paradigm provide many advantages and have distinguishing features in terms of structural compliance, dexterity, safety, and weight reduction. This paper proposes a new robotic mechanism based on tensegrity ('tension-integrity') robots and reconfigurable modular robots. The specific actuation schemes for this tensegrity robot with multiple degrees of freedom are presented. This article describes an easy-to-assemble 350 mm tensegrity based robot prototype by stacking a series of rigid struts li…
Oak Ridge Associated Universities（橡树岭联合大学）；University of California Santa Cruz（加州大学圣克鲁兹分校）；University of California San Diego（加州大学圣地亚哥分校）；NASA Ames Research Center（NASA艾姆斯研究中心）；SGT Inc.（SGT公司）
Tensegrity robots are a class of compliant robots that have many desirable traits when designing mass efficient systems that must interact with uncertain environments. Various promising control approaches have been proposed for tensegrity systems in simulation. Unfortunately, state estimation methods for tensegrity robots have not yet been thoroughly studied. In this paper, we present the design and evaluation of a state estimator for tensegrity robots. This state estimator will enable existing and future control algorithms to transfer from simulation to hardware. Our approach is based on the …
Walking quadruped robots face challenges in positioning their feet and lifting their legs during gait cycles over uneven terrain. The robot Laika is under development as a quadruped with a flexible, actuated spine designed to assist with foot movement and balance during these gaits. This paper presents the first set of hardware designs for the spine of Laika, a physical prototype of those designs, and tests in both hardware and simulations that show the prototype's capabilities. Laika's spine is a tensegrity structure, used for its advantages with weight and force distribution, and represents …
Léonard de Vinci Pôle Universitaire（莱昂纳多·达·芬奇大学中心）
Piping inspection robots play an essential role for industries as they can reduce human effort and pose a lesser risk to their lives. Generally, the locomotion techniques of these robots can be classified into mechanical and bioinspired. By using slot-follower leg mechanisms, DC-motors, and control units, a rigid caterpillar type inspection robot was designed and developed at LS2N, France . This rigid prototype helped in identifying the static forces required to accomplish good contact forces with the pipeline walls. In order to work inside curvatures, a tensegrity mechanism that uses three te…
University of California, Berkeley（加州大学伯克利分校）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；Autodesk, Inc.（欧特克公司）；Nasa Ames Research Center（NASA艾姆斯研究中心）；OpenAI；International Computer Science Institute（国际计算机科学研究所）
Tensegrity robots, composed of rigid rods connected by elastic cables, have a number of unique properties that make them appealing for use as planetary exploration rovers. However, control of tensegrity robots remains a difficult problem due to their unusual structures and complex dynamics. In this work, we show how locomotion gaits can be learned automatically using a novel extension of mirror descent guided policy search (MDGPS) applied to periodic locomotion movements, and we demonstrate the effectiveness of our approach on tensegrity robot locomotion. We evaluate our method with real-world…
Laboratoire des Sciences du Numérique de Nantes (LS2N)（南特数字科学实验室（LS2N））；Centre National de la Recherche Scientifique (CNRS)（法国国家科学研究中心（CNRS））；Université Laval（拉瓦尔大学）；École Centrale de Nantes（南特中央理工学院）
Cable-Driven Parallel Robots (CDPRs) offer high payload capacities, large translational workspace and high dynamic performances. The rigid base frame of the CDPR is connected in parallel to the moving platform using cables. However, their orientation workspace is usually limited due to cable/cable and cable/moving platform collisions. This paper deals with the design, modelling and prototyping of a hybrid robot. This robot, which is composed of a CDPR mounted in series with a Parallel Spherical Wrist (PSW), has both a large translational workspace and an unlimited orientation workspace. It sho…
We present the development of a cable-based passive forearm exoskeleton that is designed to assist supination for hemiparetic stroke survivors. Our device uniquely provides torque sufficient for counteracting spasticity within a below-elbow apparatus. The mechanism consists of a spiral single-tendon routing embedded in a rigid forearm brace and terminated at the hand and upper-forearm. A spool with an internal releasable-ratchet mechanism allows the user to manually retract the tendon and rotate the hand to counteract involuntary pronation synergies due to stroke. We characterize the mechanism…
Learning policies in simulation is promising for reducing human effort when training robot controllers. This is especially true for soft robots that are more adaptive and safe but also more difficult to accurately model and control. The sim2real gap is the main barrier to successfully transfer policies from simulation to a real robot. System identification can be applied to reduce this gap but traditional identification methods require a lot of manual tuning. Data-driven alternatives can tune dynamical models directly from data but are often data hungry, which also incorporates human effort in…
Tensegrity robots, composed of rigid rods and flexible cables, are difficult to accurately model and control given the presence of complex dynamics and high number of DoFs. Differentiable physics engines have been recently proposed as a data-driven approach for model identification of such complex robotic systems. These engines are often executed at a high-frequency to achieve accurate simulation. Ground truth trajectories for training differentiable engines, however, are not typically available at such high frequencies due to limitations of real-world sensors. The present work focuses on this…
Friction Characterization of a Cable-Driven Differential Actuation System for Lower-Limb Exoskeletons
Institute of Mechanical Intelligence, Department of Excellence in Robotics and AI, Sant'Anna School of Advanced Studies（机械智能研究所、机器人及人工智能卓越系，圣安娜高等研究学院）；Wearable Robotics s.r.l.（可穿戴机器人有限公司）
A quadcopter is an under-actuated system with only four control inputs for six degrees of freedom, and yet the human control of a quadcopter is simple enough to be learned with some practice. In this work, we consider the problem of human control of a multiple quadcopters system to transport a cable-suspended payload. The coupled dynamics of the system, due to the inherent physical constraints, is used to develop a leader-follower architecture where the leader quadcopter is controlled directly by a human operator and the followers are controlled with the proposed Payload Attitude Controller an…
Michigan State University（密歇根州立大学）；Utah State University（犹他州立大学）
This paper presents a sample-efficient data-driven method to design model predictive control (MPC) for cable-actuated soft robotics using Bayesian optimization. Instead of modeling the complex dynamics of the soft robots, the proposed approach uses Bayesian optimization to search the best-guessed low-dimensional prediction model and its associated controller to minimize the objective function of closed-loop responses. The prediction model is updated by Bayesian optimization from the closed-loop input-output data in each iteration. A linear MPC is then designed based on the updated prediction m…
A Cooperative Aerial System of A Payload Drone Equipped with Dexterous Rappelling End Droid for Cluttered Space Pickup
School of Aerospace Science and Engineering, Beihang University（北京航空航天大学航空航天科学与工程学院）；Hangzhou International Innovation Institute of Beihang University（北京航空航天大学杭州国际创新研究院）；Institute of Unmanned System, Beihang University（北京航空航天大学无人系统研究院）；Tianmushan Laboratory（天门山实验室）
This paper describes the design and control of a support and recovery system for use with planar legged robots. The system operates in three modes. First, it can be operated in a fully transparent mode where no forces are applied to the robot. In this mode, the system follows the robot closely to be able to quickly catch the robot if needed. Second, it can provide a vertical supportive force to assist a robot during operation. Third, it can catch the robot and pull it away from the ground after a failure to avoid falls and the associated damages. In this mode, the system automatically resets t…
