Development of A Three-Dimensional Guidance System for Long-Range Maneuvering of A Miniature Autonomous Underwater Vehicle

The present paper introduces a three-dimensional guidance system developed for a miniature Autonomous Underwater Vehicle（AUV）. The guidance system determines the best trajectory for the vehicle based on target behavior and vehicle capabilities. The dynamic model of this novel AUV is derived based on its special characteristics such as the horizontal posture and the independent diving mechanism. To design the guidance strategy, the main idea is to select the desired depth, presumed proportional to the horizontal distance of the AUV and the target. By connecting the two with a straight line, this strategy helps the AUV move in a trajectory sufficiently close to this line. The adjacency of the trajectory to the line leads to reasonably short travelling distances and avoids unsafe areas. Autopilots are designed using sliding mode controller. Two different engagement geometries are considered to evaluate the strategy＇s performance： stationary target and moving target. The simulation results show that the strategy can provide sufficiently fast and smooth trajectories in both target situations.

First testing of an AUV mission planning and guidance system for water quality monitoring and fish behavior observation in net cage fish farming

Recently,underwater vehicles have become low cost,reliable and affordable platforms for performing various underwater tasks.While many aquaculture systems are closed with no harmful output,open net cage fish farms and land-based fish farms can discharge significant amounts of wastewater containing nutrients,chemicals,and pharmaceuticals that impact on the surrounding environment.Although aquaculture development has often occurred outside a regulatory framework,government oversight is increasingly common at both the seafood quality control level,and at baseline initiatives addressing the basic problem of pollution generated by culture operations,e.g.the European marine and maritime directives.This requires regular,sustainable and cost-effective monitoring of the water quality.Such monitoring needs devices to detect the water quality in a large sea area at different depths in real time.This paper presents a concept for a guidance system for a carrier(an autonomous underwater vehicle)of such devices for the automated detection and analysis of water quality parameters.

Approach and landing guidance design for reusable launch vehicle using multiple sliding surfaces technique

An autonomous approach and landing（A＆L） guidance law is presented in this paper for landing an unpowered reusable launch vehicle（RLV） at the designated runway touchdown. Considering the full nonlinear point-mass dynamics, a guidance scheme is developed in threedimensional space. In order to guarantee a successful A＆L movement, the multiple sliding surfaces guidance（MSSG） technique is applied to derive the closed-loop guidance law, which stems from higher order sliding mode control theory and has advantage in the finite time reaching property.The global stability of the proposed guidance approach is proved by the Lyapunov-based method.The designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A＆L phase and instantaneous states of the RLV. Therefore, the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase. Finally, simulation results show the effectiveness of the proposed guidance law in different scenarios.