Cooperative Target Defense under Communication and Sensing Constraints

TL;DR

The work tackles cooperative target defense under partial sensing and unknown intruder dynamics by casting the problem as a decentralized nonlinear consensus among defenders. A finite-time, convexity-respecting consensus protocol is proposed, using only local communications and sensing to drive all defenders to a common capture point without requiring knowledge of the intruder's policy. A key contribution is a explicit sufficient condition involving defender speeds, sensing, and graph connectivity, plus an upper bound on the capture time that elucidates the sensing-communication tradeoff. Numerical simulations with four defenders validate the theory, quantify how sensing versus communication impacts capturability, and illustrate how parameter changes shift the safe/unsafe regions for intruder starting positions. The results provide practical guidelines for designing resilient, information-limited defender teams in pursuit-evasion settings.

Abstract

We consider a variant of the target defense problems where a group of defenders are tasked to simultaneously capture an intruder. The intruder's objective is to reach a target without being simultaneously captured by the defender team. Some of the defenders are sensing-limited and do not have any information regarding the intruder's position or velocity at any time. The defenders may communicate with each other using a connected communication graph. We propose a decentralized feedback strategy for the defenders, which transforms the simultaneous capture problem into a unique nonlinear consensus problem. We derive a sufficient condition for simultaneous capture in terms of the agents' speeds, sensing, and communication capabilities. The proposed decentralized controller is evaluated through extensive numerical simulations.

Figures (5)

• Figure 1: Left: Agents' trajectories in $\mathbb{R}^2$ where the defenders are homogeneous: $\nu_i=1$ for $i=\{1,2,3,4\}$, their communication graph is complete, and they all can sense the attacker. The intruder velocity is $\nu_5=0.1$. Right: Agents' trajectories in $\mathbb{R}^2$ for a heterogeneous group of defenders. Defender velocities are $\nu_1=1.3, \nu_2=1.4, \nu_3=1.5, \nu_4=1.4$. Defenders 2 and 3 do not sense the attacker and defenders 1 and 2 do not communicate with each other. The intruder velocity is still $\nu_5=0.1$.
• Figure 2: Capture time for different starting points of the attacker and fixed defender locations. The white region represents the attacker's starting points from which a breach of the target is inevitable. For other starting points of the attacker, the capture time is displayed using the colormap.
• Figure 3: Boundary of the non-capturable region as $\nu_4$ is varied. Here, $\nu_i=1$ for $i=\{1,2,3\}$ and $\nu_5=0.1$.
• Figure 4: For different communication graphs, the boundary of the non-capturable region is shown. Each region is shown in the same color as its corresponding communication graph. The black dot is the target $\mathcal{T}$.
• Figure 5: For different sensing capabilities, the boundary of the non-capturable region is shown. Each region is shown in the same color as its corresponding communication graph. The black dot is the target $\mathcal{T}$.

Theorems & Definitions (6)

• Lemma 1
• proof
• Theorem 1
• proof
• Remark 1
• Remark 2