Design of a Co-simulation environment for the docking maneuver of an autonomous underwater vehicle using radio frequency and acoustic hybrid communication

Official URL: http://risc01.sabanciuniv.edu/record=b1817197 (Table of Contents)

In today's world, more research is needed on both underwater communication networks and autonomous underwater vehicle control. The main reason for this is, most of the modern technologies lose its function, partially or completely, due to negative conditions in the underwater environment. In this thesis, the starting point is to create a networked control system (NCS) using acoustic and Radio Frequency (RF) hybrid communication. Acoustic communication can be used even in long ranges, up to kilometers, but it offers low data rate and high propagation delays. On the other hand, RF communication provides high data rates and low delays, however, due to high attenuation, it can only be used in a 10-meter range in the modern technology. The proposed hybrid communication system uses RF communication in 10-meter range and acoustic communication in outside of that range. A co-simulation environment with Gazebo, a realistic physics simulator of the vehicle dynamics, and TrueTime, a realistic simulator of the real-time computer and physical characteristics and protocols of the communication channel, has been created for this purpose. However, since the selected simulators both have dynamic time step solvers, the time difference between simulation times vii causes excessive time skew which can lead to instability of control loops of the NCS. Thus, a time synchronization is applied between the two simulation environments. The main contributions of this thesis are creating the co-simulation environment, solving the time synchronization problem and characterizing the synchronization delays and lowering the delays to ensure it will not affect the simulation realism.