Research on Synergy Pursuit Strategy of Multiple Underwater Robots

This paper presents a synergy pursuit strategy that multiple underwater robots pursue a single moving target based on finite state machine. The processes of the pursuit are defined as seven different states, and to implement each state, the corresponding strategies are designed. As the strategy for each state is implemented by a corresponding formation control, a synergy control law is also designed for multiple underwater robots. In the design of the pursuit strategy, the definition of encirclement is put forward for the underwater robots. Furthermore, the proof that a point is encircled by other points on the plane is given. To solve the problem of the concealment in the tracking and the pursuit, a semicircular pursuit strategy and a circular pursuit strategy are also proposed. Finally, based on this pursuit strategy, the simulation of whole process is carried out with the MOOS(Mission Oriented Operating Suite) platform, and the effectiveness of the semicircular and circular pursuit strategy are verified by lake experiment with practical robots. The results of simulation and lake experiment prove that this pursuit strategy can realize synergy tracking and pursuit for a single moving target under the given conditions.</p

Advances in Autonomous Underwater Vehicle Technologies for Enhanced Harbor Protection

This Dissertation is the culmination of coursework and research focused on the challenges of, and potential solutions to, defending harbor environments against adversarial threats. Advancements are reported on in three technology areas - perception, autonomy, and vehicle fabrication - that suggest the utilization of autonomous underwater vehicles (AUVs) as a viable harbor protection system. Chapter 2 reports a literature review documenting present-day protection systems, AUVs, and recent advancements in technology that apply to both harbor protection systems and AUVs. Chapter 3 presents a simple mathematical model of the harbor environment that is used to evaluate the effectiveness of protection solutions. An initial set of harbor protection requirements and functional objectives help define research objectives. This Dissertation also reports on research, design, and testing of technology components that enable the use of AUVs for the harbor protection problem. Chapter 4 presents a study on the application of convolutional neural network-based algorithms onto commercially available low size, weight, and power electronics to confirm that a forward looking sonar is able to detect and classify multiple divers in real time. Chapter 5 reports an autonomy architecture, as well as underlying modes and behaviors, that demonstrate how an AUV may search, detect, classify, and deny threats within a harbor environment. Chapter 6 presents a study of additive manufacturing processes and their utilization for design of novel bulkheads, custom pressure vessel structures, and a vehicle hull form. The reported hull form, with integrated hardware and autonomy, constitutes a prototype AUV that was designed and fabricated at the Johns Hopkins University Applied Physics Laboratory as part of this research. Testing of the prototype vehicle was completed to confirm hardware integration and collaborative autonomy capabilities. The testing that was presented in this Dissertation suggests that AUVs can support harbor protection functions. The Appendices include four published conference papers, one patent, and one manuscript that were completed as part of this research. The Dissertation fulfills, in part, the requirements for the Doctor of Engineering, and serves as a collection of documents that can inform future harbor protection research and technology development