Biological Snakes Research Articles

S-shaped rolling gait designed using curve transformations of a snake robot for climbing on a bifurcated pipe

In this work, we focus on overcoming the challenge of a snake robot climbing on the outside of a bifurcated pipe. Inspired by the climbing postures of biological snakes, we propose an S-shaped rolling gait designed using curve transformations. For this gait, the snake robot’s body presenting an S-shaped curve is wrapped mainly around one side of the pipe, which leaves space for the fork of the pipe. To overcome the difficulty in constructing and clarifying the S-shaped curve, we present a method for establishing the transformation between a plane curve and a 3D curve on a cylindrical surface. Therefore, we can intuitively design the curve in 3D space, while analytically calculating the geometric properties of the curve in simple planar coordinate systems. The effectiveness of the proposed gait is verified by actual experiments. In successful configuration scenarios, the snake robot could stably climb on the pipe and efficiently cross or climb to the bifurcation while maintaining its target shape.

Design and Construction of a Snake-Like Robot Implementing Rectilinear and Sidewinding Gait Motions

Bio-inspired robots offer locomotion versatility in a wide variety of terrains that conventional robots cannot access. One such bio-inspired platform is snake-like robots, which are mechanisms designed to move like biological snakes. The aim of this paper was to implement and validate, through comparison in real and simulation tests on flat terrain, the design of a snake robot that allows movements in two perpendicular planes, by the application of three-dimensional locomotion modes. The prototype robot had a modular and sequential architecture composed of eight 3D printed segments. The necessary torques for each motor are found by means of a simulation in Matlab – Simulink and the SimScape tool. The Webots mobile robotics simulator was used to create a parameterized virtual model of the robot, where two types of gaits were programmed: sidewinding and rectilinear. Results showed that the robot undertakes lower than 1 second in execution time to reach the total distance in each of the proposed marches when comparted to the simulation. In addition, mean differences of 6 cm for the distances during the sidewinding mode experiment and 1.2 cm in the deviation in the rectilinear mode on flat terrain were obtained. In conclusion, there is a great similarity between the simulation tests and those performed with the actual robot, and it was also possible to verify that the behavior of the prototype robot is satisfactory over short distances.

A Survey on Snake Robot Locomotion

Snake robots have been a topic of discussion among researchers for decades. They are potentially strong enough to bring substantial contributions to the fields which are unsafe/ narrow/ dirty/ hard reachable to human operators, such as inspections, rescue missions, firefighting, etc. Though the inventions of the wheel and legged mechanisms are amazing, they often fail when coming to these scenarios. Terrain adaptability is the vital essence of locomotion over constrained surfaces in biological snakes. But how this natural adaptability is accomplished in snake-like robots? Therefore, this paper focuses a study on factors behind the recreation of a physical snake, like the kinematics and dynamics modelling, mechanical design, and locomotion control approaches from existing literature. With their feature comparison, the simulators available for verifying the mathematical model and the feasibility of the mechanical design are also made for researchers new to the field.

Autonomous Snake Robot with Serpentine type Navigation

Biological snakes can easily maneuver through complex and undulating terrains which gives the motivation to create a bio mimic robotic snake which can easily slither through narrow spaces and uneven surfaces unlike the wheeled or legged mechanisms that have terrain limitations for its maneuverability. Such robots can be used in rescue operations in earthquake areas where it can easily crawl, surveillance and maintenance of complex or dangerous structures like pipelines in nuclear power plants. In this paper we discuss the development of autonomous snake robot with serpentine type navigation. The paper discusses in detail about the design of the robot, mathematical modelling, and motion study in virtual environment using MATLAB. The paper also discusses the controlling of the robot using Arduino Nano. The aim of the project is to develop a bio mimic snake which can maneuver over any terrains.

Motion Planning and Iterative Learning Control of a Modular Soft Robotic Snake.

Snake robotics is an important research topic with a wide range of applications, including inspection in confined spaces, search-and-rescue, and disaster response. Snake robots are well-suited to these applications because of their versatility and adaptability to unstructured and constrained environments. In this paper, we introduce a soft pneumatic robotic snake that can imitate the capabilities of biological snakes, its soft body can provide flexibility and adaptability to the environment. This paper combines soft mobile robot modeling, proprioceptive feedback control, and motion planning to pave the way for functional soft robotic snake autonomy. We propose a pressure-operated soft robotic snake with a high degree of modularity that makes use of customized embedded flexible curvature sensing. On this platform, we introduce the use of iterative learning control using feedback from the on-board curvature sensors to enable the snake to automatically correct its gait for superior locomotion. We also present a motion planning and trajectory tracking algorithm using an adaptive bounding box, which allows for efficient motion planning that still takes into account the kinematic state of the soft robotic snake. We test this algorithm experimentally, and demonstrate its performance in obstacle avoidance scenarios.

Snake-Inspired Kirigami Skin for Lateral Undulation of a Soft Snake Robot

Frictional anisotropy, as produced by the directionality of scales in snake skin, is necessary to propel snakes across flat, hard surfaces. This work illustrates the design, fabrication, and testing of a snake-inspired skin based on kirigami techniques that, when attached to a soft snake robot, improves the robot's locomotion capabilities when implementing a lateral undulation gait. Examination of snake scales in nature informed the shape and texture of the synthetic scales, which are activated through the buckling of kirigami lattices. Biological snakes have microornamentation on their scales, which is replicated by scoring ridges into the plastic skin. This microornamentation contributes to the lateral resistance necessary for lateral undulation. The skin's frictional properties were experimentally determined, as were their contributions to the locomotion of the robot across a flat, hard, textured surface. Contributions to locomotion from scale profile geometry, scale microornamentation, and scale angle of attack were identified. The range of longitudinal COF ratios was 1.0 to 3.0 and the range of lateral COF ratios was 0.9 to 3.3. The highest performing skin was the triangular scale profile with microornamentation, producing a velocity of 6 mm/s (0.03 BL/s) which is an increase of 335% over the robot with no skin when activated to maximum achievable curvature.

SnakeSIM: a ROS-based control and simulation framework for perception-driven obstacle-aided locomotion of snake robots

Biological snakes are capable of exploiting roughness in the terrain for locomotion. This feature allows them to adapt to different types of environments. Snake robots that can mimic this behaviour could be fitted with sensors and used for transporting tools to hazardous or confined areas that other robots and humans are unable to access. Snake robot locomotion in a cluttered environment where the snake robot utilises a sensory–perceptual system to perceive the surrounding operational environment for means of propulsion can be defined as perception-driven obstacle-aided locomotion (POAL). The initial testing of new control methods for POAL in a physical environment using a real snake robot imposes challenging requirements on both the robot and the test environment in terms of robustness and predictability. This paper introduces SnakeSIM, a virtual rapid-prototyping framework that allows researchers for the design and simulation of POAL more safely, rapidly and efficiently. SnakeSIM is based on the robot operating system (ROS) and it allows for simulating the snake robot model in a virtual environment cluttered with obstacles. The simulated robot can be equipped with different sensors. Tactile perception can be achieved using contact sensors to retrieve forces, torques, contact positions and contact normals. A depth camera can be attached to the snake robot head for visual perception purposes. Furthermore, SnakeSIM allows for exploiting the large variety of robotics sensors that are supported by ROS. The framework can be transparently integrated with a real robot. To demonstrate the potential of SnakeSIM, a possible control approach for POAL is considered as a case study.

OriSnake: Design, Fabrication, and Experimental Analysis of a 3-D Origami Snake Robot

Snake robots offer a useful and unique mobility platform for search-and-rescue applications. However, existing prototypes made of rigid links and joints are hampered by a lack of flexibility that limits their utility in highly cluttered, maze-like environments, and their heavy weight limits their energy-efficiency and performance in three-dimensional (3-D) tasks. To address these challenges, this letter presents a new approach using cylindrical, origami continuum modules driven by internal cables and electric motors, as well as a local feedback control system on each module. Thus, we can distribute actuation, sensing, and control for highly scalable soft robotic continuum origami systems. Using this approach, we develop a 3-D origami robotic snake that is able to locomote using lateral undulation and sidewinding gaits similar to those used by biological snakes. The proposed snake robot is a continuously deformable, lightweight, modular, and low cost robotic system made of a folded thin plastic body. We detail the design, fabrication, and control of this first 3-D origami robotic snake prototype, focusing on the analysis of locomotion parameters for each gait. We experimentally search for the optimal parameters for both types of locomotion, with maximum speeds characterized as 40.5 mm/s (0.1 body-lengths per second) for lateral undulation and 35 mm/s (0.09 body-lengths per second) for sidewinding locomotion.

Motion planning for a planar mechanical system with dissipative forces

In this paper, the geometric motion planning problem is addressed for an under-actuated mechanical system with dynamic non-holonomic constraints. Such constraints are the result of conservation of momentum that limits the mobility of the system in ambient space. However, dissipation forces due to interaction with the environment play a role enabling the system to move in constrained directions. Geometric mechanics tools are used to represent system dynamics in a structured form, which help better understand the motion planning problem. The geometric structure can be utilized to choose appropriate gaits intuitively by considering the properties of functions involved in the system dynamics. In a similar manner, dissipation forces also show the same type of geometric properties in terms of Stokes’ connection and Stokes’ Gamma functions. We can choose a gait intuitively without the need for integrating the system dynamics to generate motion in ambient space. We achieve this by exploiting the geometric properties of the friction model along with the natural dynamics of the system. By the proposed gait selection methodology, gaits are devised to move the system along a fiber direction. The simulation results are consistent with the results predicted by the proposed motion planning method. The proposed methodology is validated using experimental demonstration which also supports the simulation results. The proposed Stokes’ Height functions and Stokes’ Gamma functions can help to better understand the contribution of the dissipative forces and their anisotropy in motion of biological snakes and their robotic counterparts.

Non-iterative geometric approach for inverse kinematics of redundant lead-module in a radiosurgical snake-like robot

BackgroundSnake-like robot is an emerging form of serial-link manipulator with the morphologic design of biological snakes. The redundant robot can be used to assist medical experts in accessing internal organs with minimal or no invasion. Several snake-like robotic designs have been proposed for minimal invasive surgery, however, the few that were developed are yet to be fully explored for clinical procedures. This is due to lack of capability for full-fledged spatial navigation. In rare cases where such snake-like designs are spatially flexible, there exists no inverse kinematics (IK) solution with both precise control and fast response.MethodsIn this study, we proposed a non-iterative geometric method for solving IK of lead-module of a snake-like robot designed for therapy or ablation of abdominal tumors. The proposed method is aimed at providing accurate and fast IK solution for given target points in the robot’s workspace. n-1 virtual points (VPs) were geometrically computed and set as coordinates of intermediary joints in an n-link module. Suitable joint angles that can place the end-effector at given target points were then computed by vectorizing coordinates of the VPs, in addition to coordinates of the base point, target point, and tip of the first link in its default pose. The proposed method is applied to solve IK of two-link and redundant four-link modules.ResultsBoth two-link and four-link modules were simulated with Robotics Toolbox in Matlab 8.3 (R2014a). Implementation result shows that the proposed method can solve IK of the spatially flexible robot with minimal error values. Furthermore, analyses of results from both modules show that the geometric method can reach 99.21 and 88.61% of points in their workspaces, respectively, with an error threshold of 1 mm. The proposed method is non-iterative and has a maximum execution time of 0.009 s.ConclusionsThis paper focuses on solving IK problem of a spatially flexible robot which is part of a developmental project for abdominal surgery through minimal invasion or natural orifices. The study showed that the proposed geometric method can resolve IK of the snake-like robot with negligible error offset. Evaluation against well-known methods shows that the proposed method can reach several points in the robot’s workspace with high accuracy and shorter computational time, simultaneously.

螺旋捻転運動により直管をつなぐ曲管を走破するヘビ型ロボットの実現

Biological snakes have a soft elongated body and adapt to various environment in spite of simple form. By using them for engineering, snake robots can move in complex environment. In the case that a snake-like robot goes into pipes, it can use helical rolling motion. In previous study, a method to make a bending helical shape for a snake-like robot is proposed. However the method is not utilized in a bent pipe connected with straight pipes. In this paper, we realize going through the pipes by using helical rolling motion and bending helical rolling motion. In addition, by considering a direction of bending helical rolling motion, we propose a method to adjust a snake robot to a bent pipe. The proposed method is verified by experiments.

Kinematic gait synthesis for snake robots

Snake robots are highly articulated mechanisms that can perform a variety of motions that conventional robots cannot. Despite many demonstrated successes of snake robots, these mechanisms have not been able to achieve the agility displayed by their biological counterparts. We suggest that studying how biological snakes coordinate whole-body motion to achieve agile behaviors can help improve the performance of snake robots. The foundation of this work is based on the hypothesis that, for snake locomotion that is approximately kinematic, replaying parameterized shape trajectory data collected from biological snakes can generate equivalent motions in snake robots. To test this hypothesis, we collected shape trajectory data from sidewinder rattlesnakes executing a variety of different behaviors. We then analyze the shape trajectory data in a concise and meaningful way by using a new algorithm, called conditioned basis array factorization, which projects high-dimensional data arrays onto a low-dimensional representation. The low-dimensional representation of the recorded snake motion is able to reproduce the essential features of the recorded biological snake motion on a snake robot, leading to improved agility and maneuverability, confirming our hypothesis. This parameterized representation allows us to search the low-dimensional parameter space to generate behaviors that further improve the performance of snake robots.

Snake Robots From Biology to Nonlinear Control

Inspired by the motion of biological snakes, this paper presents an overview of recent results in modelling and control of snake robots. The objective of the research underlying this paper is to contribute to the mathematical foundation of the control theory of snake robots. To this end, the paper presents two mathematical models of planar snake robot dynamics, which are employed to investigate stabilisability and controllability properties of snake robots. Furthermore, averaging theory is used to derive properties of the velocity dynamics of snake robots. Moreover, a straight line path following controller is proposed and cascaded systems theory is employed to prove that the controller K -exponentially stabilizes a snake robot to any desired straight path.

Analysis of Creeping Locomotion of a Snake-like Robot on a Slope

The diverse locomotion modes and physiology of biological snakes make them supremely adapted for their environment. To model the noteworthy features of these snakes we have developed a snake-like robot that has no forward direction driving force. In order to enhance the ability of our robot to adapt to the environment, in this study we investigate the creeping locomotion of a snake-like robot on a slope. A computer simulator is presented for analysis of the creeping locomotion of the snake-like robot on a slope, and the environmentally-adaptable body shape for our robot is also derived through this simulator.

Dynamic Analysis of a 3-Dimensional Snake Robot

Snake-like robots that behaves biological snakes' characteristics have possibility to make them supremely adapted for environment. In this paper, we firstly formulate the kinematics and the dynamics of a 3-dimensional snake robot and then analyze the sinus-lifting creeping motion as an example. The sinus-lifting motion is a phenomenon observed during rapid motion of the snake, and is an adaptive function peculiar to regular creeping motion, designed to prevent slippage in the normal direction of the body and to allow application of the greatest possible motive force. In this paper, the sinus-lifting motion was imaged as the creeping motion in 2-dimensional plane with different distribution of normal reaction forces for simplicity. Comparison has been performed between the creeping locomotion with uniform normal reaction forces, and the sinus lifting creeping motion where the normal reaction forces are distributed by the weight with respect to the body curvature. As a result, we know that the snake-like robot in the sinus-lifting creeping motion mode with curvature-weighted normal reaction forces moves at higher speed than that in the creeping motion mode with uniform normal reaction forces.