This paper introduces a novel continuous-time dynamic average consensus
algorithm for networks whose interaction is described by a strongly connected
and weight-balanced directed graph. The proposed distributed algorithm allows
agents to track the average of their dynamic inputs with some steady-state
error whose size can be controlled using a design parameter. This steady-state
error vanishes for special classes of input signals. We analyze the asymptotic
correctness of the algorithm under time-varying interaction topologies and
characterize the requirements on the stepsize for discrete-time
implementations. We show that our algorithm naturally preserves the privacy of
the local input of each agent. Building on this analysis, we synthesize an
extension of the algorithm that allows individual agents to control their own
rate of convergence towards agreement and handle saturation bounds on the
driving command. Finally, we show that the proposed extension additionally
preserves the privacy of the transient response of the agreement states and the
final agreement value from internal and external adversaries. Numerical
examples illustrate the results.