Chasing an evader while keeping visual contact, or active line of sight (LOS), is a challenging problem that arises in applications involving the surveillance, observation, or interception of one of more targets in structured as well unstructured environments. Generally, the problem is addressed in the literature by means of motion planning techniques [1] because they provide obstacle-free paths toward one or more goals, and they can take into account different constraints defined by the user. References [2,3] proposed motion planners for observing a target maintaining a fixed distance. Pursuers with limited sensing ranges were considered in [4]. Reference [5] introduced the concept of strong mutual visibility: two regions were strongly mutually visible if every point of one region was able to see all the points of the other region. This concept was used for the design of motion planners for maintaining the visibility of one [6,7] or more targets [8,9] with unpredictable motion, under incomplete information. The major drawback of motion planners is the need for adequate computational resources for path computation, which is usually a time-consuming process that may limit the real-time implementation of the control strategy. Moreover, a previous processing of the environment is requested in order to have a representation suitable for path computation. These problems become even more critical in typical missile guidance scenarios where vehicle speed and time to accomplish the mission are important. The development of a guidance law can overcome some of these problems, and it provides a simple solution implementable in real time. Historically, target engagement is a guidance problem that can be addressed using proportional navigation guidance (PNG) or its modified versions [10–12]. In a previous paper [13], Cancemi et al. proposed a modification for the classical PNG aimed at intercepting a target in a structured environment while maintaining the visual contact during the engagement. An augmentation term for the PNG was introduced based on a visibility function, i.e., a function that provided a measure of target visibility in a structured environment. Exploiting this function, the pursuer could maintain the visual contact during the engagement or could recover good visibility when the target hid behind an obstacle. Although the augmentation proposed showed good results in simulation, its introduction into a classic PNG law was based on solely heuristic arguments. The aim of the present Note is to provide a formal derivation for a visibility-based guidance law, i.e., a control strategy for intercepting a target in a structured environment while maintaining a good visual contact during the engagement.

Visibility Augmented Proportional Navigation Guidance

FRANZINI, GIOVANNI
Primo
Formal Analysis
;
POLLINI, LORENZO
Penultimo
Validation
;
INNOCENTI, MARIO
Ultimo
Conceptualization
2018-01-01

Abstract

Chasing an evader while keeping visual contact, or active line of sight (LOS), is a challenging problem that arises in applications involving the surveillance, observation, or interception of one of more targets in structured as well unstructured environments. Generally, the problem is addressed in the literature by means of motion planning techniques [1] because they provide obstacle-free paths toward one or more goals, and they can take into account different constraints defined by the user. References [2,3] proposed motion planners for observing a target maintaining a fixed distance. Pursuers with limited sensing ranges were considered in [4]. Reference [5] introduced the concept of strong mutual visibility: two regions were strongly mutually visible if every point of one region was able to see all the points of the other region. This concept was used for the design of motion planners for maintaining the visibility of one [6,7] or more targets [8,9] with unpredictable motion, under incomplete information. The major drawback of motion planners is the need for adequate computational resources for path computation, which is usually a time-consuming process that may limit the real-time implementation of the control strategy. Moreover, a previous processing of the environment is requested in order to have a representation suitable for path computation. These problems become even more critical in typical missile guidance scenarios where vehicle speed and time to accomplish the mission are important. The development of a guidance law can overcome some of these problems, and it provides a simple solution implementable in real time. Historically, target engagement is a guidance problem that can be addressed using proportional navigation guidance (PNG) or its modified versions [10–12]. In a previous paper [13], Cancemi et al. proposed a modification for the classical PNG aimed at intercepting a target in a structured environment while maintaining the visual contact during the engagement. An augmentation term for the PNG was introduced based on a visibility function, i.e., a function that provided a measure of target visibility in a structured environment. Exploiting this function, the pursuer could maintain the visual contact during the engagement or could recover good visibility when the target hid behind an obstacle. Although the augmentation proposed showed good results in simulation, its introduction into a classic PNG law was based on solely heuristic arguments. The aim of the present Note is to provide a formal derivation for a visibility-based guidance law, i.e., a control strategy for intercepting a target in a structured environment while maintaining a good visual contact during the engagement.
2018
Franzini, Giovanni; Luca, Tardioli; Pollini, Lorenzo; Innocenti, Mario
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/876567
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