Surge-yaw Control of a Hybrid Underwater Robotic Vehicle

An underwater robotic vehicle is being developed at the UFABC (Universidade Federal do ABC) which has as main mission the inspection of ship hull thickness using ultrasonic transducers. This is a hybrid ROV (Remotely Operated Vehicle) due to its extreme locomotion capabilities adapted of the terrain tracked vehicles. This paper presents the surgeyaw control system of a new hybrid underwater vehicle that has two operation modes: free-flight and crawling. The free-flight mode uses a set of thrusters and the crawling mode uses two motorized tracks. The adherence between tracks and ship hull is guaranteed by applying a force normal to the hull surface from vertical thrusters. The conventional PID approach is used in order to control the horizontal dynamics composed of three degrees of freedom. The generated control signals are used to command the two thrusters to move the vehicle in the free-flight mode, and to command the two DC motors to move tracks of the crawling mode. The controlled vehicle responses are shown by numerical results focused to guarantee the performance specifications of the challenging and typical maneuvers.