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Progress On A Perimeter Surveillance Problem
Designing protocols for multi-agent interaction that achieve the desired behavior is a challenging and error-prone process. The standard practice is to manually develop proofs of protocol correctness that rely on human intuition and require significant effort to develop. Even then, proofs can have mistakes that may go unnoticed after peer review, modeling and simulation, and testing. The use of formal methods can reduce the potential for such errors. In this paper, we discuss our experience applying model checking to a previously published multi-agent protocol for unmanned air vehicles. The original publication provides a compelling proof of correctness, along with extensive simulation results to support it. However, analysis through model checking found an error in one of the proof’s main lemmas. In this paper, we start by providing an overview of the protocol and its original “proof” of correctness, which represents the standard practice in multi-agent protocol design. We then describe how we modeled the protocol for a three-vehicle system in a model checker, the counterexample it returned, and the insight this counterexample provided. We also discuss benefits, limitations, and lessons learned from this exercise, as well as what future efforts would be needed to fully verify the protocol for an arbitrary number of vehicles.
This paper describes a design flow and supporting tools to significantly improve the design and verification of complex cyber-physical systems. We focus on system architecture models composed from libraries of components and complexity-reducing design patterns having formally verified properties. This allows new system designs to be developed rapidly using patterns that have been shown to reduce unnecessary complexity and coupling between components. Components and patterns are annotated with formal contracts describing their guaranteed behaviors and the contextual assumptions that must be satisfied for their correct operation. We describe the compositional reasoning framework that we have developed for proving the correctness of a system design, and provide a proof of the soundness of our compositional reasoning approach. An example based on an aircraft flight control system is provided to illustrate the method and supporting analysis tools.
This paper poses the cooperative perimeter-surveillance problem and offers a decentralized solution that accounts for perimeter growth (expanding or contracting) and insertion/deletion of team members. By identifying and sharing the critical coordination information and by exploiting the known communication topology, only a small communication range is required for accurate performance. Simulation and hardware results are presented that demonstrate the applicability of the solution.
In this paper, we consider the problem of exploring an unknown environment with a team of robots. As in single-robot exploration the goal is to minimize the overall exploration time. The key problem to be solved in the context of multiple robots is to choose appropriate target points for the individual robots so that they simultaneously explore different regions of the environment. We present an approach for the coordination of multiple robots, which simultaneously takes into account the cost of reaching a target point and its utility. Whenever a target point is assigned to a specific robot, the utility of the unexplored area visible from this target position is reduced. In this way, different target locations are assigned to the individual robots. We furthermore describe how our algorithm can be extended to situations in which the communication range of the robots is limited. Our technique has been implemented and tested extensively in real-world experiments and simulation runs. The results demonstrate that our technique effectively distributes the robots over the environment and allows them to quickly accomplish their mission.
The paper reviews the past and present results in the area of decentralized control of large-scale complex systems. An emphasis is laid on decentralization, decomposition, and robustness. These methodologies serve as effective tools to overcome specific difficulties arising in large-scale complex systems such as high dimensionality, information structure constraints, uncertainty, and delays. Several prospective topics for future research are introduced in this contents. The overview is focused on recent decomposition approaches in interconnected dynamic systems due to their potential in providing the extension of decentralized control into networked control systems.
In this paper, we present an exploration system for multiple unmanned aerial vehicles (UAVs) navigating through a simulated
unknown region that contains obstacles of unknown shape, size, and initial position. The UAVs have to explore and monitor
the region continuously. The UAVs have limited sensor and communication ranges and kinematic constraints. The environment
may have blind alleys that may cause the UAV to collide with an obstacle. Since the UAVs have limited sensor range, they cannot
detect whether the alleys lead to an obstacle or not. Due to the presence of multiple agents and kinematic constraints, the
UAVs have to cooperate with each other in selecting their paths, otherwise they may collide with each other. The physical
and sensor constraints on the UAVs, coupled with uncertainty in the environment makes the problem of multiple UAVs exploring
the unknown region a difficult problem. We developed an exploration system that uses (a) an exploration algorithm to generates
safe paths for travel in narrow corridors and (b) a dynamic leader selection scheme to take the presence of multiple agents
into account. We also determine the minimum communication range required to ensure no collisions occur inside the narrow corridors.
Monte-Carlo simulation were carried out to analyze the effect on area coverage with changes in number of agents, sensor range,
and communication range.
A hierarchical proof of DPSS-A
- David Greve
A Computational Logic Handbook, Academic Press international series in formal methods
- Robert S Boyer
- Strother Moore