I. Introduction
Given a connected network with a group of agents each of which has its own local time-varying reference signal, dynamic average consensus (DAC) aims to design a distributed algorithm to ensure that each agent can track the average of all the time-varying reference signals by exchanging local information with its neighbors [1]. During the past decade, there has been more and more attention devoted to dynamic average consensus due to its significance in various applications such as formation control [2], sensor fusion [3], robotic manipulator control [4], [5] and distributed optimization [6], [7].