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In this investigation, a smart collision avoidance control design, which integrates a collision avoidance navigation and a nonlinear optimal control method, is developed for unmanned surface vessels (USVs) under randomly incoming ships and fixed obstacle encounter situations. For achieving collision avoidance navigation, a fuzzy collision risk indicator and a fuzzy collision avoidance acting timing indicator are developed. These two risk indicators can offer effective pre-alarms for making the controlled USVs to perform dodge actions in time when obstacles appear. As to nonlinear optimal control law, it provides a precise trajectory tracking ability for the controlled USVs to follow a collision avoidance trajectory, which is generated via a smart collision avoidance trajectory generator. Finally, a power allocation method is used to transform the desired control law into available actuator outputs to guide the USVs to follow a desired collision avoidance trajectory. From simulation results, the proposed collision avoidance strategy reveals a promising collision avoidance performance and an accurate trajectory tracking ability with respect to fixed objects and randomly moving ships under the effect of environmental ocean disturbances.

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A novel nonlinear control law for the purpose of lateral control of a missile is presented in this paper. This approach can be applied to generate lateral control commands for a missile operating in flight regimes where the effectiveness of conventional aerodynamic surfaces is reduced (i.e. high angle of attack). The design objective is to specify one control law that satisfies the H2 performance for the nonlinear attitude tracking design of missiles. In general, it is hard to obtain the closed‐form solutions from this nonlinear attitude tracking problem. Fortunately, because of the adequate choice of state variable transformation, the nonlinear H2 attitude tracking problem of the missile can be reduced to solving one nonlinear time varying Riccati‐like equation. Furthermore, one closed‐form solution to this equation can be obtained in a very simple form for the preceding control design.

A nonlinear guidance law based on a fuzzy model is proposed for tactical missiles pursuing maneuvering targets in three-dimensional (3-D) space. In the proposed guidance scheme, the relative motion equations between the missile and target are first interpolated piecewise by Takagi-Sugeno linear fuzzy models. Then, a nonlinear fuzzy guidance law is designed to eliminate the effects of approximation error and external disturbances to achieve the desired goal. The linear matrix inequality (LMI) technique is then employed to treat this optimal guidance design in consideration of control constraints. Finally, the problem is further transformed into a standard eigenvalue problem so that it can be efficiently solved via a convex optimization algorithm, which is available from a numerical computation software.

For solving the transformation problem between the desired nonlinear control laws and installed actuators’ input commands of torpedo-like underwater vehicles, one closed-form control allocation method is proposed in this article. The goal of this study is to optimally distribute the desired nonlinear control law to each single actuator installed on the torpedo-like underwater vehicle. The first step of this proposed control allocation method is to arrange the required types, numbers, and positions of the installed actuators and then build up the thrust configuration matrix for the developed torpedo-like underwater vehicle. In this step, the desired nonlinear control law can be optimally distributed to output commands of installed actuators based on the optimization method. Next, through collecting the input and output data of each installed actuator by practical experiments, the mathematical transformation of input and output commands of each installed actuator can be found. For verifying performance of this proposed control allocation method, simulations with the robust trajectory tracking design of a torpedo-like underwater vehicle with four fins, four rudders, and one thruster are executed in this investigation.

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