Bounded Consensus Tracking of Heterogeneous Multiagent Systems Under Digraphs With Diverse Communication and Input Delays.

We study the bounded consensus tracking problem for the heterogeneous multiagent system composed of single- and double-integrator agents in the presence of diverse communication and input delays. The objective is to ensure bounded tracking when only a portion of agents has access to the desired trajectory while agents interact with each other through a directed communication network. To achieve this goal, we propose a protocol consisting of a consensus-based trajectory estimator followed by a controller tracking the estimated trajectory for each agent. Though the agents involved in the mission are heterogeneous, the estimators of all the agents are designed as coupled single integrators to provide estimates of the acceleration, velocity, and position along the desired trajectory. The coupled single-integrator estimator followed by the tracking controller strategy leads to a decoupling whereby the allowable estimator gains for an agent depend only on its communication delays and its controller gains depend only on its input delay. The tracking errors remain bounded even if the desired acceleration is unknown to all the agents. Simulation results are carried out to validate the proposed consensus tracking algorithm.

Circumnavigation on Multiple Circles Around a Nonstationary Target With Desired Angular Spacing.

In this article, the objective for a group of nonholonomic agents is to achieve multicircular circumnavigation with any desired angular spacing around a nonstationary target. A cooperative protocol is proposed to achieve this objective and, additionally, generalizes the circumnavigation problem of unicycle vehicles around a target (moving and stationary). Due to the nonholonomic constraints, existing protocols cannot be extended directly to achieve this objective. Thus, the proposed algorithm is worked out from the desired geometry to achieve the objective. A fixed-time consensus estimator is designed under a cyclic digraph to arrive at the desired interagent angular separation in the target-centric frame. The target information and desired formation parameters are assumed to be known to only one agent partially. Due to uncertainty in the target's motion, it is assumed that the target's acceleration and angular velocity are unknown. Fixed-time estimators under a digraph address the lack of information. The tracking controller drives the agents to the desired position around the target, thus making the errors go to zero instead of any finite bounds. The controller guarantees the bounded control effort irrespective of the error magnitude. The numerical examples are presented to show the effectiveness of the algorithm.