There have been many
studies on the optimal tuning and control
performance assessment (CPA) of the PID controller. In the optimal
tuning, the trade-off between the setpoint tracking and the disturbance
rejection performance is a challenge. Minimum output variance (MOV)
is very widely used as a benchmark for CPA of PID, but it is difficult
to be observed due to the non-convex optimization problem. In this
paper, a new multiobjective function, considering both the OV in the
CPA problem and integral of absolute error, is proposed to tune PID
for this trade-off. The CPA-related non-convex problem and tuning-related
multiobjective problem are solved by teaching–learning-based
optimization, which guarantees a tighter lower bound for MOV due to
the excellent capability of local optima avoidance and has higher
computational efficiency due to the low complexity. The numerical
examples of CPA problems show that the algorithm can generate better
MOV than existing methods with less calculation time. The relationship
between the weight of the multiobjective function and the performance,
including setpoint tracking, stochastic and step disturbance rejection,
is revealed by simulation results of the tuning method applied to
two temperature control systems. The proper adjustment of the weight
with a multistage strategy can achieve the trade-off to obtain excellent
setpoint tracking performance in the initial stage and satisfying
disturbance rejection performance in the steady stage.