• Engine Speed Control Apparatus shows the problems of regulating the speed of rotating machines, especially problems with non-linear control systems.  
• The basic purpose is to adjust a motorised valve to regulate the engine speed under load. A d.c. generator connects to the engine output and loads the engine.
• It is a scale-model engine, driven by compressed air (not supplied) for safety. 

Advanced experiments show:

• Non-linearity compensation using dither signals.
• Multiple loop and minor loop.
• System modelling from step response information.
• P+I control and root locus methods.