The ball and beam system consists of a long beam which can be tilted by a servo or electric motor together with a ball rolling back and forth on top of the beam. It is a popular textbook example in

control theory Control theory is a field of control engineering and applied mathematics that deals with the control system, control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the applic ...

. The significance of the ball and beam system is that it is a simple system which is open-loop

unstable In dynamical systems instability means that some of the outputs or internal state (controls), states increase with time, without bounds. Not all systems that are not Stability theory, stable are unstable; systems can also be marginal stability ...

. Even if the beam is restricted to be very nearly horizontal, without active

feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause and effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handle ...

, it will swing to one side or the other, and the ball will roll off the end of the beam. To stabilize the ball, a control system which measures the position of the ball and adjusts the beam accordingly must be used. In two dimensions, the ball and beam system becomes the ball and plate system, where a ball rolls on top of a plate whose inclination can be adjusted by tilting it forwards, backwards, leftwards, or rightwards.

External links

Ball and beam with various controls strategies

Ball and beam 1: basics

Ball and beam with comprehensive dynamics and movies
{{tech-stub Control engineering