Swarm Robotics Indresh Yadav

Introduction Swarm Robotics studies a particular class of multi-robot system. It emphasis aspects like decentralization of control, robustness, flexibility and scalability.

Inspiration Inspired by the behavior of social insects. Each single ant acts autonomously following simple rules and locally interacting with the other ants. A coherent and self-organizing behavior can be observed at the colony level.

The Swarm-Bot An s-bot is a small mobile autonomous robot with self-assembling capabilities. It weighs 700 g and its main body has a diameter of about 12 cm. The traction system is composed of both tracks and wheels.

Cylindrical turret mounted on the chassis by means of a motorized joint. The gripper is mounted on Turret as some freedom for lifting object. Gripper used for connecting to S-Bots and objects.

Four proximity sensors placed under the chassis (ground sensors), torque and traction sensor. Eight light sensors uniformly distributed around the turret ,two humidity sensor & 3-axis accelometer. Each robot is also equipped with sensors and devices to detect and communicate with each other. Consists of camera, LED, microphone, loudspeaker.

Synchronization The task requires that each s-bot in the group displays a simple periodic behavior. It means their oscillations are in phase with each other. In order to communicate with each other, s-bots produce a continuous tone with fixed frequency and intensity.

It is perceived by every robot in arena. The tone is perceived in a binary way. One sensory neuron is used for perception of sound.

Co-ordinated Motion It is a basic ability due to physical interaction among s-bots. They must co-ordinate their action to choose common direction of movement. It can efficiently move only if the chassis of the assembled s-bots have the same orientation.

A common direction of motion on the basis of the information provided by their traction sensor. Four sensory neurons encode the intensity of traction along four directions, corresponding to the direction of the semi-axes of the chassis’ frame. 2 motor neurons control wheels and turret chassis motor.

Hole avoidance Individual s-bots cannot avoid holes due to their limited perceptual apparatus. To safely navigate arena consisting of holes Co-ordination motion must be performed. Presence of holes must be communicated.

Communication among the s-bots Direct Interactions setup (DI) Direct Communication setup (DC) Evolved Communication setup (EC) In all three setups (DI, DC and EC), s-bots are equipped with traction and ground sensors. In DC and EC, microphones and speakers are also used.

Advantages Fault tolerance De-centralized approach Flexibility Robustness

Limitation Self organizing behavior. Interaction between individual robot. Interaction among components. Encoding of robots.

Application Plume tracing Obstacle avoidance Search and rescue Surveillance/coverage Convoy formation Move towards goal by avoiding hurdles

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