Researcher in Control Systems.

The context of multiagent pursuit-evasion is an important aspect in robotics, aerospace and control engineering, and path planning. In multi-vehicle pursuit-evasion scenarios, the pursuer (incoming threat to the evader) tries to minimize its relative distance with respect to the evader (targeted vehicle). On the other hand, the evader attempts to throw the pursuer off its trail and deploys a defending interceptor (defender) to assist in avoiding possible capture by the pursuer. The evader, therefore, cooperates with the defender, which attempts to neutralize the pursuer, before the pursuer can capture the evader. In this regard, the evader and the defender are a cooperating team, while the pursuer is in the opposition.

The resulting three-player engagement scenarios are different from the the traditional one-to-one engagements, and present a formidable challenge in the design of defense strategy, as the evader-defender team may use different levels of cooperation to neutralize the threat.

A part of our research proposes an impact-time control based cooperative guidance approach to defend the evader from the pursuer. If the defender intercepts the pursuer before the latter gets a chance to come in the vicinity of the evader, the mission can be deemed a success. The evader-defender team can use various levels of cooperation to achieve this objective, depending on the availability of communication resources and desired simplicity during the implementation. The evader aligns itself on the collision course with the pursuer to lure the latter, and launches the defender against it. Once on the collision course, the pursuer is expected to become non-maneuvering, and the time of interception for the pursuer-evader engagement can be estimated with a reasonable accuracy. The defender can then intercept the non-maneuvering pursuer at a suitable impact-time, which is sufficiently lesser than the estimated time-to-go of the pursuer-evader engagement, even if the evader does not continuously communicate its states to the defender. On the other hand, if the evader communicates with the defender, then explicit time-to-go information may not be necessary, and the defender can intercept the pursuer with a pre-specified time margin. This time margin may be chosen to ensure safe distance between pursuer and evader, at the time instant when the defender intercepts the pursuer.