Differential wheeled robot

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A three wheeled differentially steered robot

A differential wheeled robot is a mobile robot whose movement is based of two separately driven wheels placed on either side of the robot body. It can thus change its direction by varying the relative rate of rotation of its wheels and hence does not require an additional steering motion.

More number of wheels (not driven) may be added to the robot for additional balance.

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Path of wheels through a turn.The wheels are not connected,unlike it might appear.

If both the wheels are driven in the same direction and speed,the robot will go in a straight line. Otherwise, depending on the speed of rotation and its direction,the centre of rotation may fall anywhere in the line joining the two wheels. Since the direction of the robot is dependent on the rate and direction of rotation of the two driven wheels, these quantities should be sensed and controlled precisely.This usually creates some problem.If both wheels are turned with equal speed in opposite directions,as it is clear from the diagram shown,the robot will rotate about the central point of the axis.

A differentially steered robot is similar to the differential gears used in automobiles in that both the wheels can have different rates of rotations,but unlike the differential gearing system,a differentially steered system will have both the wheels powered.Differential wheeled robots are used extensively in robotics, since their motion is easy to program and can be well controlled. Virtually all consumer robots on the market today use differential steering primarily for its low cost and ultra-simplicity.