Further results on event-based PID controller

In this paper, some improvements of the simple event-based PID controller presented by K-E Å rzén in [2] are proposed. This controller, contrary to a time-triggered controller which calculates the control signal at each sampling time, calculates the new control signal only when the measurement signal sufficiently changes. In the original work of Å rzén, a safety maximum period is added forcing the control to be recomputed even if the measurement signal remains unchanged. The contribution of this paper is to propose a scheme to avoid this re-computation. Besides a noticeable reduction of the mean control computation cost, the performance of the closed loop system is also improved.