With quasi-stochastic and wide frequency spectrum, chaos can improve concealment capability of underwater vehicle such as a warship. Therefore, making a regular dynamical system chaotic or preserving its chaos state is meaningful, and such a research is often called chaos anti-control. This paper focused on making chaos in brushless direct current motor (BLDCM) system of underwater vehicle with a novel method called synchronization. By synchronizing the BLDCM system with a known chaotic system, we design a controller to solve the chaos anti-control problem. The theory foundation is Lyapunov's stability theorem and the conclusion is verified by numerical simulations.


Chaos is a two-edged sword as other things. On one hand, chaos can produce some results difficult to forecast and it is apt to make a system disorganized, when we should take measure to depress or eliminate it and the research in point is called chaos control. On the other hand, chaos is also desirable and even quite useful under certain circumstances, and the corresponding research is called chaos anti-control. Up to now chaos anticontrol has been applied in human brain (Schiff, etc, 1994), heart beat regulation (Brandt and Chen, 1997), motor system (Chau, Ye, Gao, et al., 2004; Ge, Cheng and Chen, 2004), so on and so forth. As to an underwater vehicle such as a warship, chaos' characteristics such as quasi-stochastic and wide frequency spectrum are useful because it can improve concealment capability. In this paper we focused on producing chaos in an underwater BLDCM system with the so-called chaos synchronization (Liu, Zhu and Ding, 2007, 2009). Bringing out chaos synchronization is our key task and the first step need choose a known chaotic system. In this paper we choose n-scroll Chua's system owing to its simple structure.

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