This paper presents an optimization-based motion planning methodology for snake robots operating in constrained environments. By using a reduced-order model, the proposed approach simplifies the planning process, enabling the optimizer to autonomously generate gaits while constraining the robot's footprint within tight spaces. The method is validated through high-fidelity simulations that accurately model contact dynamics and the robot's motion. Key locomotion strategies are identified and further demonstrated through hardware experiments, including successful navigation through narrow corridors.
Gaits engineered for snake-like robots to rotate in-place instrumentally fill a gap in the set of locomotive gaits that have traditionally prioritized translation. This paper designs a Turn-in-Place gait and demonstrates the ability of a shape-centric modeling framework to capture the gait's locomotive properties. Shape modeling for turning involves a time-varying continuous body curve described by a standing wave. Presumed viscous robot-ground frictional interactions lead to body dynamics conditioned on the time-varying shape model. The dynamic equations describing the Turn-in-Place gait are …
In this paper, we propose a method for generating undulatory gaits for snake robots. Instead of starting from a pre-defined movement pattern such as a serpenoid curve, we use a Model Predictive Control approach to automatically generate effective locomotion gaits via trajectory optimization. An important advantage of this approach is that the resulting gaits are automatically adapted to the environment that is being modeled as part of the snake dynamics. To illustrate this, we use a novel model for anisotropic dry friction, along with existing models for viscous friction and fluid dynamic effe…
End-to-End Multi-Task Policy Learning from NMPC for Quadruped Locomotion
Institute for Artificial Intelligence and Autonomous Systems (A2S)（人工智能与自主系统研究所）；Bonn-Rhein-Sieg University of Applied Sciences（波恩-莱茵-锡格应用科学大学）；Humanoid Robots Lab（人形机器人实验室）；University of Bonn（波恩大学）；Lamarr Institute for Machine Learning and Artificial Intelligence（Lamarr机器学习与人工智能研究所）；Center for Robotics（机器人中心）；Fraunhofer Institute for Intelligent Analysis and Information Systems（弗劳恩霍夫智能分析与信息系统研究所）
Hierarchical RL-Guided Large-scale Navigation of a Snake Robot
Khoury College of Computer Science, Northeastern University（东北大学Khoury计算机科学学院）；SiliconSynapse Laboratory, Department of Electrical and Computer Engineering, Northeastern University（东北大学电气与计算机工程系硅突触实验室）
Carnegie Mellon University（卡内基梅隆大学）；Georgia Institute of Technology（佐治亚理工学院）
Snake robots composed of alternating single-axis pitch and yaw joints have many internal degrees of freedom, which make them capable of versatile three-dimensional locomotion. In motion planning process, snake robot motions are often designed kinematically by a chronological sequence of continuous backbone curves that capture desired macroscopic shapes of the robot. However, as the geometric arrangement of single-axis rotary joints creates constraints on the rotations in the robot, it is challenging for the robot to reconstruct an arbitrary 3D curve. When the robot configuration does not accur…
University of Notre Dame（圣母大学）；Robotics at Google（谷歌机器人部门）
Specialized motions such as jumping are often achieved on quadruped robots by solving a trajectory optimization problem once and executing the trajectory using a tracking controller. This approach is in parallel with Model Predictive Control (MPC) strategies that commonly control regular gaits via online re-planning. In this work, we present a nonlinear MPC (NMPC) technique that unlocks on-the-fly re-planning of specialized motion skills and regular locomotion within a unified framework. The NMPC reasons about a hybrid kinodynamic model, and is solved using a variant of a constrained Different…
The Geometry of Optimal Gait Families for Steering Kinematic Locomoting Systems
Collaborative Robotics and Intelligent Systems (CoRIS) Institute at Oregon State University（俄勒冈州立大学协作机器人与智能系统（CoRIS）研究所）；Johns Hopkins University（约翰斯·霍普金斯大学）
DePaul University（德保罗大学）；University of Arkansas（阿肯色大学）
Snakes are a remarkable evolutionary success story. Many snake-inspired robots have been proposed over the years. Soft robotic snakes (SRS) with their continuous and smooth bending capability better mimic their biological counterparts' unique characteristics. Prior SRSs are limited to planar operation with a limited number of planar gaits. We propose a novel SRS with spatial bending and investigate snake locomotion gaits beyond the capabilities of the state-of-the-art systems. We derive a complete floating-base kinematic model of the robot and use the model to derive jointspace trajectories fo…
Snake robots, comprised of sequentially connected joint actuators, have recently gained increasing attention in the industrial field, like life detection in narrow space. Such robots can navigate through the complex environment via the cooperation of multiple motors located on the backbone. However, controlling the robots in an unknown environment is challenging, and conventional control strategies can be energy inefficient or even fail to navigate to the destination. In this work, a snake locomotion gait policy is developed via deep reinforcement learning (DRL) for energy-efficient control. W…
DePaul University（德保罗大学）；Texas A&M University（得克萨斯农工大学）；Georgia Institute of Technology（佐治亚理工学院）；Louisiana S. University（路易斯安那州立大学）
Soft robotic snakes made of compliant materials can continuously deform their bodies and, therefore, mimic the biological snakes' flexible and agile locomotion gaits better than their rigid-bodied counterparts. Without wheel support, to date, soft robotic snakes are limited to emulating planar locomotion gaits, which are derived via kinematic modeling and tested on robotic prototypes. Given that the snake locomotion results from the reaction forces due to the distributed contact between their skin and the ground, it is essential to investigate the locomotion gaits through efficient dynamic mod…
Technical University of Munich（慕尼黑工业大学）；Ludwig Maximilian University of Munich（路德维希-马克西米利安-慕尼黑大学）；Sun Yat-sen University（中山大学）
Similar to their counterparts in nature, the flexible bodies of snake-like robots enhance their movement capability and adaptability in diverse environments. However, this flexibility corresponds to a complex control task involving highly redundant degrees of freedom, where traditional model-based methods usually fail to propel the robots energy-efficiently. In this work, we present a novel approach for designing an energy-efficient slithering gait for a snake-like robot using a model-free reinforcement learning (RL) algorithm. Specifically, we present an RL-based controller for generating loc…
DePaul University（德保罗大学）；Texas A&M University（德克萨斯农工大学）；Georgia Institute of Technology（佐治亚理工学院）
Soft robotic snakes (SRSs) have a unique combination of continuous and compliant properties that allow them to imitate the complex movements of biological snakes. Despite the previous attempts to develop SRSs, many have been limited to planar movements or use wheels to achieve locomotion, which restricts their ability to imitate the full range of biological snake movements. We propose a new design for the SRSs that is wheelless and powered by pneumatics, relying solely on spatial bending to achieve its movements. We derive a kinematic model of the proposed SRS and utilize it to achieve two sna…
Collaborative Robotics and Intelligent Systems (CoRIS) Institute, Oregon State University（俄勒冈州立大学协作机器人与智能系统（CoRIS）研究所）；Bard College at Simon’s Rock（巴德学院西蒙洛克分校）；Olin College of Engineering（奥林工程学院）；Carnegie Mellon University（卡内基梅隆大学）
Snake robots are characterized by their ability to navigate through small spaces and loose terrain by utilizing efficient cyclic forms of locomotion. Soft snake robots are a subset of these robots which utilize soft, compliant actuators to produce movement. Prior work on soft snake robots has primarily focused on planar gaits, such as undulation. More efficient spatial gaits, such as sidewinding, are unexplored gaits for soft snake robots. We propose a novel means of constructing a soft snake robot capable of sidewinding, and introduce the Helical Inflating Soft Snake Robot (HISSbot). We valid…
Locomotion of an Elastic Snake Robot via Natural Dynamics
German Aerospace Center (DLR), Robotics and Mechatronics Center (RMC)（德国航空航天中心（DLR）机器人与机电中心）；Technical University of Munich (TUM), Department of Computer Engineering（慕尼黑技术大学（TUM）计算机工程系）
Rectilinear forms of snake-like robotic locomotion are anticipated to be an advantage in obstacle-strewn scenarios characterizing urban disaster zones, subterranean collapses, and other natural environments. The elongated, laterally-narrow footprint associated with these motion strategies is well-suited to traversal of confined spaces and narrow pathways. Navigation and path planning in the absence of global sensing, however, remains a pivotal challenge to be addressed prior to practical deployment of these robotic mechanisms. Several challenges related to visual processing and localization ne…
Non-planar snake gaits: from Stigmatic-starts to Sidewinding
Harvard University（哈佛大学）；Indian Institute of Technology Bombay（印度理工学院孟买分校）；National Center for Supercomputing Applications（国家超级计算应用中心）；Carl R. Woese Institute for Genomic Biology（卡尔·R·沃斯基因组生物学研究所）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；A.T. Still University of Health Sciences（A.T. 斯蒂尔健康科学大学）；Kirksville College of Osteopathic Medicine（柯克斯维尔整骨医学院）
School of Computing, DePaul Univeristy（德保罗大学计算机学院）
Bioinspired snake robotics has been a highly active area of research over the years and resulted in many prototypes. Much of these prototypes takes the form of serially jointed-rigid bodies. The emergence of soft robotics contributed to a new type of snake robots made from compliant and structurally deformable modules. Leveraging the controllable large bending, these robots can naturally generate various snake locomotion gaits. Here, we investigate the swimming locomotion of soft robotic snakes. A numerically efficient dynamic model of the robot is first derived. Then, a distributed contact mo…
Towards Obstacle-Avoiding Control of Planar Snake Robots Exploring Neuro-Evolution of Augmenting Topologies
Department of Computer Science and Information Science, BITS Pilani Hyderabad Campus（计算机科学与信息科学系，比斯潘学院海得拉巴校区）；Department of Electrical and Electronics Engineering, BITS Pilani Hyderabad Campus（电气与电子工程系，比斯潘学院海得拉巴校区）
Georgia Institute of Technology（佐治亚理工学院）；Carnegie Mellon University（卡内基梅隆大学）
Reorientation (turning in plane) plays a critical role for all robots in any field application, especially those that in confined spaces. While important, reorientation remains a relatively unstudied problem for robots, including limbless mechanisms, often called snake robots. Instead of looking at snakes, we take inspiration from observations of the turning behavior of tiny nematode worms C. elegans. Our previous work presented an in-place and in-plane turning gait for limbless robots, called an omega turn, and prescribed it using a novel two-wave template. In this work, we advance omega turn…
University of California San Diego（加州大学圣地亚哥分校）；NASA Jet Propulsion Laboratory（美国国家航空航天局喷气推进实验室）
This paper presents the design and performance of a screw-propelled redundant serpentine robot. This robot comprises serially linked, identical modules, each incorporating an Archimedes' screw for propulsion and a universal joint (U-Joint) for orientation control. When serially chained, these modules form a versatile snake robot platform which enables the robot to reshape its body configuration for varying environments and gait patterns that would be typical of snake movement. Furthermore, the Archimedes' screws allow for novel omni-wheel drive-like motions by speed controlling their screw thr…
Georgia Institute of Technology（佐治亚理工学院）；Carnegie Mellon University（卡内基梅隆大学）
Limbless robots have the potential to maneuver through cluttered environments that conventional robots cannot traverse. As illustrated in their biological counterparts such as snakes and nematodes, limbless locomotors can benefit from interactions with obstacles, yet such obstacle-aided locomotion (OAL) requires properly coordinated high-level self-deformation patterns (gait templates) as well as low-level body adaptation to environments. Most prior work on OAL utilized stereotyped traveling-wave gait templates and relied on local body deformations (e.g., passive body mechanics or decentralize…
