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Robust Multi-Agent Pursuit with Preemptive Communication via Reachability-Based Control Barrier Functions

Robust Multi-Agent Pursuit with Preemptive Communication via Reachability-Based Control Barrier Functions

Madison Book, Justin Bradley · N/A · 2026

reinforcement-learning control
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Summary

Safe multi-agent coordination typically assumes what real-world, deployed, resource-constrained robots cannot provide: continuous, perfect state sharing. Robust control strategies must be complemented with robust communication strategies to deliver resilient deployments.

Abstract Summary

Safe multi-agent coordination typically assumes what real-world, deployed, resource-constrained robots cannot provide: continuous, perfect state sharing. Robust control strategies must be complemented with robust communication strategies to deliver resilient deployments. In this work, we propose a unified control/communication strategy that provides safe control to guarantee inter-agent safety under intermittent communication and demonstrate its effectiveness in a pursuit-evasion scenario. Each agent computes the reachable set of neighboring agents based on the last state information received, then solves for a safe control input based on control barrier functions to ensure agents avoid collision. We prove that inter-agent collision avoidance is guaranteed provided communication staleness remains bounded. As the reachable set inflates between state transmissions, each agent reasons about when to preemptively transmit its state information to neighboring agents based on novel metrics characterizing uncertainty risk and kinematic risk. We implement and simulate a variety of pursuit-evasion scenarios and show that preemptive communication reduces messages by 77.5% compared to periodic and event-triggered baselines with zero collisions.

Key Points

  • Safe multi-agent coordination typically assumes what real-world, deployed, resource-constrained robots cannot provide: continuous, perfect state sharing.
  • Robust control strategies must be complemented with robust communication strategies to deliver resilient deployments.
  • In this work, we propose a unified control/communication strategy that provides safe control to guarantee inter-agent safety under intermittent communication and demonstrate its effectiveness in a pursuit-evasion scenario.
  • Each agent computes the reachable set of neighboring agents based on the last state information received, then solves for a safe control input based on control barrier functions to ensure agents avoid collision.
  • We prove that inter-agent collision avoidance is guaranteed provided communication staleness remains bounded.

PROBLEM FORMULATION

We consider a system of $n_{p}$ pursuers and $n_{e}$ evaders operating in $\mathbb{R}^{3}$. Pursuers and evaders are indexed by $\mathrm{P}=\{1,\ldots,n_{p}\}$ and $\mathrm{E}=\{1,\ldots,n_{e}\}$ respectively. Each agent’s state and dynamics are known and given by where $p,v,u\in\mathbb{R}^{3}$ denote position, velocity and control input, respectively.

We denote pursuer $i$’s state as $x_{i}$ and pursuer $i$’s assigned evader’s state as $x_{e_{i}}$.

PROBLEM FORMULATION — Robust Multi-Agent Pursuit with Preemptive Communication via Reachability-Based Control Barrier Functions
Fig. 1: Demonstration of the preemptive communication mechanism. Pursuers $i$ and $j$ are represented as squares, their assigned evader is represented as a circle. On the left, pursuer $i$ identifies that it is at risk of collision with pursuer $j$ and therefore communicates its current state. Subsequently, $j$’s estimated reachable set for $i$ is reset, illustrated by the reachable set around $i$ shrinking on the right.

REACHABILITY-BASED CONTROL BARRIER FUNCTIONS

Since pursuer $i$ does not have continuous access to neighbor $j$’s state information, pursuer $i$ over-approximates the set of states that $j$ may occupy based on the last transmitted state $\xi_{ji}$. As $\tau_{ji}$ increases, the true position of $j$ may deviate according to unknown and bounded control inputs.

REACHABILITY-BASED CONTROL BARRIER FUNCTIONS — Robust Multi-Agent Pursuit with Preemptive Communication via Reachability-Based Control Barrier Functions
Fig. 2: Snapshot of a simulation with 3 pursuers and 2 evaders. Pursuers are represented by squares, evaders by circles. Arrows indicate current velocity direction. Faint large spheres surrounding pursuers represent evader sensing range. Darker spheres represent predicted reachable sets.

PREEMPTIVE COMMUNICATION

Theorem 1 guarantees safety provided $\omega_{ij}(x_{i},t_{k})\geq 0$ can be enforced at each time step, keeping the QP ( 17 ) feasible. QP feasibility is threatened as $\tau_{ij}$ grows (i.e., the reachable set inflates, reducing control authority). The objective of the proposed communication strategy is to preemptively transmit state information to preserve QP feasibility while minimizing unnecessary communication.

PREEMPTIVE COMMUNICATION — Robust Multi-Agent Pursuit with Preemptive Communication via Reachability-Based Control Barrier Functions
Fig. 3: Simulation metrics for the 3 pursuer 2 evader case shown in Figure 2 . Distance, velocity, total risk, kinematic risk, and uncertainty risk plots follow pursuer 1 in Figure 2 . The preemptive communication mechanism ensures pursuers 1 and 0 communicate more frequently than pursuers 1 and 2 as they are at higher risk of collision. The pursuer-evader distance graph shows pursuers closing on and capturing their assigned evaders.

Results

In this section, we evaluate our proposed framework in a decentralized pursuit-evasion setting with multiple pursuers and evaders. We present the effectiveness of the preemptive communication strategy against baseline communication models. The simulation consists of multiple cooperative pursuers attempting to capture multiple adversarial evaders.

Pursuers follow the dynamics outlined in ( 1 ) and use the safe controller outlined in Section III-B to enforce inter-agent collision avoidance.

Sources and Demonstrations

Figures are reproduced from Book et al. See the full paper for experimental details and the project page, when the paper links one, for demonstrations and videos.

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