Time response parameters and control design for second-order nonminimum-phase systems

The article considers the step and impulse response of second-order linear systems with a positive zero. A particular parameterization of the system equations is proposed which enables good assessment of the influence of its parameters on transients. Expressions missing in the literature are derived for step response parameters such as the values of undershoot, overshoot, time of inverse response, rise time and settling time, as well as of impulse response. Based on them, a precise time-domain approach to design feedforward, feedback and mixed feedback- feedforward control structures for nonminimum phase objects is presented that considers both setpoint tracking and disturbance rejection.