To zero or to hold control inputs in lossy networked control systems?

This paper studies the LQ-like performance of networked control systems where control packets are subject to losses. In particular we explored the two simplest compensation strategies commonly found in the literature: the zero-input strategy where the input to the plant is set to zero if a packet is dropped, and the hold-input strategies where the previous control input is used if packet is lost. We derived numerical solutions for computing the optimal static gain for both strategies and we compared their performance on some numerical examples. Interestingly, none of the two can be claimed superior to the other, even for simple scalar systems, as there are scenarios where one performs better then the other and vice-versa.