Biological Snake Research Articles

Locomotion gait control of snake robots based on a novel unified CPG network model composed of Hopf oscillators

Snake robots with limbless structure and rich locomotion gaits have been designed and built for wide application in various fields including military reconnaissance, pipeline operation, disaster search and rescue, etc. However, the problem how to flexibly and smoothly control switch and change of different locomotion gaits is still facing enormous challenges. A novel unified design rule of the CPG network model composed of improved Hopf oscillators is proposed, based on which a variety of different network structures can be created by designing connection distances and coupling weights among all oscillator units. Through the relationships between the control parameters of the Hopf oscillator, decoupling of the bifurcation parameters is achieved to solve inconsistent output waveform amplitude when the bifurcation parameters are not completely equal. Furthermore, five typical movement modes of biological snake are designed and smooth switch between different locomotion gaits is realized. A control system is constructed based on the Robot Operating System (ROS) and a prototype of snake robot is built, and the effectiveness of the proposed CPG model in controlling locomotion gaits was verified through simulations and experiments. The CPG modeling approach has important theoretical significance and practical instructive value for motion planning and gait control of snake robots in complex environments.

Analysis and Optimization Based on Factors Affecting the Spiral Climbing Locomotion of Snake-like Robot

The snake-like robot is a limbless bionic robot widely used in unstructured environments to perform tasks with substantial functional flexibility and environmental adaptability in complex environments. In this paper, the spiral climbing motion of a snake-like robot on the outer surface of a cylindrical object was studied based on the three-dimensional motion of a biological snake, and we carried out the analysis and optimization of the motion-influencing factors. First, the spiral climbing motion of the snake-like robot was implemented by the angle control method, and the target motion was studied and analyzed by combining numerical and environmental simulations. We integrated the influence of kinematics and dynamics factors on the spiral climbing motion. Based on this, we established a multi-objective optimization function that utilized the influence factors to optimize the joint module. In addition, through dynamics simulation analysis, the change of the general clamping force of the snake-like robot’s spiral climbing motion was transformed into the analysis of the contact force between the joint module and the cylinder. On the basis of the results, the effect of the control strategy adopted in this paper on the motion and change rule of the spiral climbing motion was analyzed. This paper presents the analysis of the spiral climbing motion, which is of great theoretical significance and engineering value for the realization of the three-dimensional motion of the snake-like robot.

유전 알고리즘을 이용한 뱀형 로봇 주행 패턴 생성

This paper presents a novel method of designing an efficient locomotion pattern generating algorithm for snake robots by a genetic algorithm (GA). In search and rescue operations in disaster areas, a snake robot requires multiple locomotion patterns. To overcome the complexity of snake robot control, we used a central pattern generator (CPG)-based control method which mimics the motion of a biological snake. GA was used to optimize CPG parameters to maximize locomotion performance. The locomotion performance according to the CPG parameters change was analyzed using the snake robot simulator. The proposed locomotion pattern generation algorithm evolved quickly for the target performance and obtained CPG parameters for the desired locomotion.

Experimental Study on Motion Control of Rope-Driven Snake Manipulator Using Velocity Mapping Method

The rope-driven snake manipulator is a bionic mechanism with hyper redundant DOFs and can be applied in narrow and confined environments, such as surgery, spacecraft, nuclear plant, etc. The kinematic mapping expressed by the rope length, joint angle and end pose is highly nonlinear and difficult to be calculated. Moreover, the control methods with rope length as input are prone to redundant driving ropes getting stuck due to differences in model and actual mechanism. Therefore, the perfect kinematic mapping of the rope-driven snake manipulator is necessary for designing high-efficiency motion controllers. In this paper, an analytical mapping about the velocities of ropes, joints and end is established and verified. Firstly, a prototype inspired by the biological snake spine is designed. And then the Jacobian matrix representing the velocity mapping is derived and analyzed in detail. The joint and rope velocities are optimized by configuring the null space vector of the Jacobian matrix. Based on the velocity mapping and optimization, a motion control scheme for the snake manipulator is established to realize servo control of the joints and end. Finally, the trajectory tracking simulation and experiment are executed to verify the velocity mapping theory and control scheme. This research can provide solutions for the complex motion control problems of subsequent snake manipulators.

A RESCUE MECHANISM FOR BOREHOLE ACCIDENTS USING SNAKE BOTS

Several deplorable incidents have brought home the dangers of uncovered bore wells and tube wells following death of the children. For tragedies that keep striking with such regularity in India, bore well rescue of children is an immense need of the hour. In this paper, a snake robot is introduced that is a highly versatile robot that resembles a biological snake. The bots can be made very small so that it can crawl into confined spaces where any rescue is impossible. Along with snake robot, the whole system consists of monitoring and motor set up to monitor and lift the child safe from the pit.

Biological Warfare and Snake Venom for Poliomyelitis and ALS: The Little Known Entwined History of Failed Ethics and a Reasonable Therapeutic Hypothesis

Biological Warfare and Snake Venom for Poliomyelitis and ALS: The Little Known Entwined History of Failed Ethics and a Reasonable Therapeutic Hypothesis

DEVELOPMENT OF A FLEXIBLE SERPENTINE ROBOT FOR DISASTER SURVEILLANCE OPERATIONS

This paper presents the development of a snake robot with vision system. This can be used for disaster aid and lessen the danger that the rescuers may encounter. The design of the snake robot considers the use of its own body segments for motion using rectilinear motion rather than using wheels. The use of segments enables the snake to move on flat and uneven terrain. Servo motors will be used for the movement of each joint and it will be powered by a lithium-polymer battery. Accelerometers and gyroscopes will serve as the input and orientation sensors, a head-mounted camera will be used to detect its location and where it is moving. An Arduino Pro Mini will be used for the controller and will be configured to receive commands from an XBee wireless transmission transceiver from the base computer. A graphical user interface in a base computer will serve as the interface of the robot’s operator and the robot. Its main movement will be based on a biological snake’s rectilinear motion which is embedded in the robot’s control system.

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.

Hybrid Modelling and Control of Obstacle-Aided Snake Robot Locomotion

A snake can traverse cluttered and irregular environments by using irregularities around its body as push points to aid the propulsion. This characteristic feature of biological snake locomotion, which is denoted as obstacle-aided locomotion, is investigated for snake robot locomotion purposes in this paper. The paper presents a hybrid model of the dynamics of a planar snake robot interacting with obstacles in its environment. Obstacle contact forces are calculated by formulating and solving a linear complementarity problem (LCP). The existence and uniqueness properties of the state evolution of the hybrid model are investigated. The paper also presents a hybrid control strategy employing measured contact forces to maintain propulsion while simultaneously preventing the snake robot from being jammed between obstacles in its path. The simulation results validate the hybrid modelling approach and the effectiveness of the proposed control strategy.

지능형 뱀 로봇에 관한 연구

기존 이동로봇의 활발한 연구와 더불어 다양한 형태의 이동로봇이 등장하였다. 이에 본 논문에서는 8축으로 구성된, 총 16 Degree Of Freedom을 가지는 다 관절 뱀 로봇을 제작하였다. 뱀 로봇은 지면과의 진행 마찰력을 고려하여 무동력 바퀴를 사용하였다. 또한 PC Cam과 초음파 센서를 사용하여 각 관절이 움직일 수 있는 Joint Angle을 나타내기 위하여 Target의 색상과 거리를 입력으로 하였다. 뱀 로봇은 머리부분, 몸통 그리고 꼬리부분으로 나뉘어 진행하는 방식을 가지며 PC Cam 을 통해 화면에 보여지는 움직이는 특정 목표물에 대하여 진행을 하며, 진행 중 움직이거나 고정되어있는 Obstacle이 포착될 경우 충돌회피를 통하여 Target을 추종하는 방식을 실험적으로 보이고자 한다. There come various types of robot with researches for mobile robot. This paper introduces the multi-joint snake robot having 16 degree of freedom and composing of eight-axis. The biological snake robot uses the forward movement friction and the proposed artificial snake robot uses the un-powered wheel instead of the body of snake. To determine the enable joint angle of each joint, the controller inputs are considered such as color and distance using PC Camera and ultra-sonic sensor module, respectively. The movement method of snake robot is sequential moving from head to tail through body. The target for movement direction is decided by a certain article be displayed in the PC Camera. In moving toward that target, if there is any obstacle then the snake robot can avoid by itself. In this paper, we show the method of snake robot for tracing the target with experiment.

Dissociations between Covariation Bias and Expectancy Bias for Fear-relevant Stimuli

The illusory correlation paradigm of Tomarken, Mineka, and Cook (1989) was used to examine bias in threat appraisal for biological (snake, spider) and technological (gun, knife) fear-relevant stimuli. Subjects showed bias in terms of higher on-line shock expectancy ratings and skin conductance responses, and higher post-experimental judgements of shock covariation, for fear-relevant stimuli. However, there were multiple dissociations between the measures: (1) expectancy bias was observed for both biological and technological stimuli, whereas covariation bias was restricted to biological stimuli; (2) prior fear of the target stimulus had no effect on expectancy bias, but covariation bias was restricted to high fear subjects; and (3) covariation bias was observed at the end of the experiment, by which time expectancy bias had disappeared. These results suggest that covariation bias is not simply a continuation of a pre-experimental expectancy bias.