On Off Control 1 Pole

Cuthbert Nyack

One of the simplest nonlinearities occurs in on off control. The applet below shows a first order system with on off control illustrating the cycling of the output.
1/a is the time constant of the system and L is the value, that the output would rise towards in the absence of on off control.
Both a and L affect the cycling frequency and the "shape" of the waveform. When controlling these systems a and L are usually fixed and control is achieved by the changing the upper and lower levels Ul and Ll to get an acceptable frequency and amplitude of the on off cycling.

Gif image below shows how applet should appear.

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