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Full Paper Proc. of Int. Conf. on Advances in Robotic, Mechanical Engineering and Design 2011

Conceptual design of a lateral undulation and side winding motion mechanism in a snake robot V.S.Rajashekhar1, and R.Senthil2 1

Student, Adhiparasakthi Engineering College/Department of Mechanical Engineering, Chennai, India Email: vsrajashekhar@gmail.com 2 Professor, Adhiparasakthi Engineering College/Department of Mechanical Engineering, Chennai, India Email: senradarjun@yahoo.co.in Abstract—A snake robot’s high degree of freedom allows the structure to move in various directions on its path. The flapping cum forward push action by the links attached to the servo motors and stepper motor makes the snake robot exhibit linear and lateral undulation movement. The side winding movement is made possible by expanding the elastic band comprising of ball bearings in such a way that it lifts off from the ground and exhibits the movement through axial rotation.

B. Side winding Only two points of contact are maintained with the ground. The segments are not in contact with the surfaces. They are lifted and moved to the side. They then become the new contact points. The previous contact point is then lifted and moved. Repeating this pattern, the snake moves in a sidewise direction. This is shown in Fig. 2.

Index terms— Lateral undulation mechanism, Friction pads, Piston rod connector, Side winding mechanism, Snake robot.

I. INTRODUCTION Linear, lateral undulation movement and side winding movement play an important role in the snake robot locomotion. The snake robot moves forward due to the various mechanisms exhibited by the various sections of it. By these movements, the snake robot finds applications in industries to search for small parts that are lost while fixing and repairing. It can be used in the maintenance of thermal power plants where they can easily crawl throughout the boiler surface. It can also be used for security purposes and to help the fire rescue team to travel in the smoke and find people or identify the source of fire. In this paper, mechanisms for the linear, lateral undulation and side winding locomotion are first designed and explained about their working. Then their arrangement in a snake robot is shown.

Figure 2. Side winding motion [1]

III. LINEAR AND LATERAL UNDULATION MECHANISM A. Introduction The linear and lateral undulation motion is made possible by a periodic braking mechanism. It has a suitable friction pad in order to make a particular segment stable when the motors push forward the segment that is in front of it. Due to this, alternate compression and expansion occurs in the compression sections that are attached in between the segments and the snake robot moves forward. In order to reduce the friction between the base of the snake robot and the moving surface, friction reducing bearings are used.

II. BIOLOGICAL SNAKE MOVEMENTS

B. Friction reducing bearings In this type of movement, there are four ball bearings in the lower side of each segment to provide a smooth motion on a flat surface.

The lateral undulation and the side winding motion of a snake are as follows. A. Lateral undulation The lateral undulation gait produces propulsion, by simultaneously moving the body sections. The sections continuously move from side to side perpendicular to the direction of forward motion. This is shown in Fig. 1.

Figure 3. The screw provides adjustable holding

Figure 1. Lateral undulation motion

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____ ________ _______ _______ ________ _______ ____ 1 Author, Tel.: +91 9840468079; 2 Co-Author, Tel.: +91 98404 68079; Received on May 30, 20 11; Accepted on July 26, 2011

© 2011 AMAE DOI: 02.ARMED.2011.01.506

Figure 4. Ball bearing at the base

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