ABSTRACT
This paper presents a target tracking control method for a biomimetic underwater vehicle named RobCutt-II. The RobCutt-II is propelled by double undulatory fins which are distributed on both sides. In order to implement target tracking and observation in a certain distance, we propose a method by decoupling the target tracking control problem into distance, heading and depth control problems. Based on this idea, we design a target tracking controller composed of a navigation system, a distance controller, a heading controller, a depth controller and a switching logic controller. The simulation results verify the effectiveness of the proposed method on the biomimetic underwater vehicle.
Underwater vehicles play an important role in marine geological surveys and underwater rescue. Unlike traditional underwater vehicles driven by axial propellers, biomimetic underwater vehicles (BUVs) are propelled by undulatory fins for high mobility in complex underwater environments. Moreover, high stability, low noise, and small environmental disturbance are the advantages of biomimetic underwater vehicles compared with traditional underwater vehicles.
A variety of biomimetic underwater vehicles have been developed by scientists around the world. A BUV was designed by Delft University of Technology in the Netherlands (Simons, Bergers, Henrion, Hulzenga, Jutte, Pas, Van Schravendijk, Vercruyssen and Wilken, 2009). An undulatory fin propelled underwater vehicle was designed by Osaka University (Rahman, 2012). Zhou et al. from Nanyang Technological University developed a CPG-controlled underwater vehicle mimicking devil fish (Zhou and Low, 2012). In our previous work, we designed a biomimetic underwater vehicle propelled by undulatory fins named RobCutt-II (Wang, Wang and Wang, 2016). By means of different undulatory modes of the double fins, the RobCutt-II generates forces in the forward direction, vertical direction and moment to change the heading angle. However, the RobCutt-II cannot generate effective lateral force, which is considered as an underactuated system.
Many interesting method and results have been presented for underactuated systems. For example, Aguiar et al. proposed a control method for an underwater vehicle without lateral and vertical control (Aguiar and Pascoal, 2007). Yang et al. designed a robust trajectory tracking controller for marine surface vessels (Yang, Du, Liu, Guo and Abraham, 2014). Zhou et al. designed a path following method using the extended state observer and the neural network. (Peng, Wang and Han, 2019). In some underwater observation tasks, the underactuated underwater vehicles are required to track and to keep a certain distance from the target for observing. Existing researches pay little attention to this issue.