Mecanum Wheel

This is the mecanum wheel, a wheel which can move a vehicle in any direction.It is a conventional wheel with a series of rollers attached to its circumference. Each of these rollers typically has an axis of rotation at 45° to the plane of the wheel and at 45° to a line through the centre of the roller parallel to the axis of rotation of the wheel. Robots using mecanum wheels are usually four-wheeled. By alternating wheels with left and right-handed rollers, in such a way that each wheel applies force roughly at right angles to the wheelbase diagonal the wheel is on, the vehicle is stable and can move in any direction. For turning, we vary the speed and direction of rotation of each wheel.For more illustration, moving all four wheels in the same direction causes forward or backward movement, running the wheels on one side in the opposite direction to those on the other side causes rotation of the vehicle around itself (360°), while running the wheels on one diagonal in the opposite direction to those on the other diagonal causes sideways movement !!!Combinations of these wheel motions allow for vehicle motion in any direction with any vehicle rotation (including no rotation at all).The YouTube link below - which isn't mine - shows a car with mecanum wheels, and demonstrates its weird movement.