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 mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a ...

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

unstable In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...

. 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 handled ...

, 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 A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large industrial c ...

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 & Beam with various controls strategies

Ball and Beam 1: basics

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