
Linear systems 37
The dyna mics of a c ontrol system may be characterised by considering the
nature of its respo nse to particular inputs. Since there is an infinite number
of different input signals w hich could be applied to any system, it is usual to
consider a subset of the most important, useful or common types of signals
which the system is expected to encounter. The most common type s of input
signals used to evaluate performance in control engineering are impulse, step
and ramp signals. Here, we focus on the response to step inputs, since this
reveals the limitations of performance of a system when it is subject to rapidly
changing inputs, e.g ...