||Unmanned underwater vehicles (UUVs), including autonomous underwater vehicles (AUVs) and remotely underwater vehicles (ROVs), are primarily used to perform various tasks regarding ocean investigation and seafloor search. The key to allow underwater vehicles to complete complex underwater activities, especially near the seafloor, is the precise motion control of underwater vehicles. The development of underwater vehicles' control rules is mostly based on underwater vehicles' dynamic equations of motion, i.e. their dynamic model. However, such dynamic model essentially contains a number of unknown parameters. Thus, in order to achieve the precise control of underwater vehicles, it is important to have an effective and accurate system identification method.|
Compared with other sensors, the prominent advantage of the vision technology is that, due to its high sampling rate, it can capture more information on an underwater vehicle's dynamic motion, leading to its capability of producing more accurate hydrodynamic parameters. In recent years, due to the improved semiconductor laser performances and the mature digital camera technologies, a laser imaging system is becoming an attractive and affordable payload device for a UUV. Therefore, this research proposes a method that adopts laser line scanning to identify the hydrodynamic parameters of an AUV and studies the feasibility of the method.
According to the experimental results, compared with using the AUV displacement data generated by a single thrust, the hydrodynamic parameters, obtained using the AUV displacement data generated by different thrusts, can lead to a dynamic model that can characterize the AUV motions under different thrusts more accurately. Such dynamic models can also generate simulated AUV paths adequately close to the actual AUV paths. Therefore, the experimental results validate the feasibility of applying laser line scanning to the AUV hydrodynamic parameter identification.