Design Of Distributed Motion Control Software For ROVs Based On QNX Real-time Operating System

ROVs(Remotely Operated Vehicles)are playing an increasingly more important role in the fields of marine resource exploration and exploitation,due to their unique advantages such as cost-effectiveness,ease in deployment and recovery and high efficiency.As operation of ROV is based on remote control,distributed control software is a key component of the control system.A typical ROV distributed motion control software is composed of the surface control sub-system and vehicle control sub-system.The former,running on the vehicle control computer on board the vehicle,manages a wide-range of sensors and data flow and executes control commands.The latter is required to provide a graphical user interface for human pilots to monitor and manoeuvre the vehicle.The vehicle control sub-system and surface control sub-system are communicating with each other though local area network.In this paper,a distributed motion control software for remotely operated vehicles(ROVs)is developed to improve the real-time performance of the ROV motion control system.The timeline scheduling scheme for periodic tasks of various periods,is adopted for all tasks to complete their execution before the individual deadline.A set of ROV motion control software based on QNX real-time operating system is also developed.Both the software test and in-water experiments have validated the reliability and real-time control performance of the software developed.