13 research outputs found

    Head-raising of snake robots based on a predefined spiral curve method

    Get PDF
    © 2018 by the authors. A snake robot has to raise its head to acquire a wide visual space for planning complex tasks such as inspecting unknown environments, tracking a flying object and acting as a manipulator with its raising part. However, only a few researchers currently focus on analyzing the head-raising motion of snake robots. Thus, a predefined spiral curve method is proposed for the head-raising motion of such robots. First, the expression of the predefined spiral curve is designed. Second, with the curve and a line segments model of a snake robot, a shape-fitting algorithm is developed for constraining the robot's macro shape. Third, the coordinate system of the line segments model of the robot is established. Then, phase-shifting and angle-solving algorithms are developed to obtain the angle sequences of roll, pitch, and yaw during the head-raising motion. Finally, the head-raising motion is simulated using the angle sequences to validate the feasibility of this method

    Motion control of a snake robot moving between two non-parallel planes

    Get PDF
    A control method that makes the head of a snake robot follow an arbitrary trajectory on two non-parallel planes, including coexisting sloped and flat planes, is presented. We clarify an appropriate condition of contact between the robot and planes and design a controller for the part of the robot connecting the two planes that satisfies the contact condition. Assuming that the contact condition is satisfied, we derive a simplified model of the robot and design a controller for trajectory tracking of the robot’s head. The controller uses kinematic redundancy to avoid violating the limit of the joint angle and a collision between the robot and the edge of a plane. The effectiveness of the proposed method is demonstrated in experiments using an actual robot

    Unified Approach to the Motion Design for a Snake Robot Negotiating Complicated Pipe Structures

    Get PDF
    A unified method for designing the motion of a snake robot negotiating complicated pipe structures is presented. Such robots moving inside pipes must deal with various “obstacles,” such as junctions, bends, diameter changes, shears, and blockages. To surmount these obstacles, we propose a method that enables the robot to adapt to multiple pipe structures in a unified way. This method also applies to motion that is necessary to pass between the inside and the outside of a pipe. We designed the target form of the snake robot using two helices connected by an arbitrary shape. This method can be applied to various obstacles by designing a part of the target form specifically for given obstacles. The robot negotiates obstacles under shift control by employing a rolling motion. Considering the slip between the robot and the pipe, the model expands the method to cover cases where two helices have different properties. We demonstrated the effectiveness of the proposed method in various experiments

    Hoop-Passing Motion for a Snake Robot to Realize Motion Transition Across Different Environments

    Get PDF
    A snake robot performs diverse motions. To realize a wide range functions in a complex environment, it is necessary to transition between various motions suited to each environment. In this article, we propose a method of transitioning the motion of a snake robot across different environments to expand the application environment of the robot. We first find that the motion at the connection point between two motions must coincide with the tangential movement during motion transition across different environments. We then design a gait called the circular pedal wave. This circular pedal wave allows a hoop-passing motion in which the whole body moves as if it is passing through a virtual hoop fixed in space in sequence from its head through combination with a proposed shift part. The hoop-passing motion allows motion transition across different environments. We propose three application examples of this hoop-passing motion, namely passing through a hole in a wall, entering an underfloor, and attaching to a ladder. We report on experiments conducted to verify the effectiveness of the proposed method and to realize the described motions

    식물의 움직임을 모사한 수분 반응성 액추에이터의 개발

    Get PDF
    학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 8. 김호영.It is a general notion that animals are motile but plants are not. Thus, most of efforts to develop biologically inspired robots are focused on mimicking motions of animals. However, some plants generate motions without muscles like animals to generate motions. Plants rely on either supply or deprival of water from plant tissues to make motions. Some species of plants such as wild wheat, Erodium, Pelargonium, and pinecones can be actuated when the environmental humidity changes. Their tissues are in general composed of highly oriented two layers, one of which is hygroscopically active while the other is inactive. Inspired by this structure, we fabricated an actuator which generates motions in response to humidity change. We newly developed an electrospinning process which can result in a fibrous layer with fast response rate to humidity cahgne. Using this actuator we demonstrated a simple robot actuated by water vapor, which we named Hygrobot.1. Introduction 1 2. Fabrication of Hygroactuator 3 2.1 Bioinspiration 3 2.2 Fabrication methods 7 3. Analysis of Hygroactuator 11 3.1 Diffusion model 11 3.2 Discretized multi-layer model 13 4. Hygrobot 17 4.1 Fabrication of Hygrobot 17 4.2 Velocity of Hygrobot 20 4.3 Optimal design for the fastest Hygrobot 22 4.4 Comparisons 24 5. Conclusions 26 References 27 Abstract (in Korean) 30Maste
    corecore