Design Of Small Intelligent Autopilot Based On ARM

Autopilot,the core unit for ship heading control,directly controls the steering gear according to operator’s instructions and current states of the ship so that the ship course could be changed or kept.Nowadays,the research and design of autopilot has become an important project in the field of ship.The development of society also sets a higher request for economy hardware and the stability of control algorithm.This paper,based on ARM,designs a small intelligent autopilot which embeds LQR as the intelligent control algorithm in the micro controllers to complete a test simulation in closing loop state.Firstly,this paper provides an overview on autopilot’s system function and illustrates three gear control patterns including the Follow-up pattern,the Auto pattern and the Track pattern.This paper further analyzes autopilot’s power supply condition taking both the main and auxiliary power into account.The display function and operate mode have been analyzed as well.Secondly,this paper has accomplished the design and implementation of autopilot.As for the microprocessor,LPC2119 is chosen as the main control chip for both steering control unit and display-control unit.Power supply unit,display-control unit,steering control unit and algorithm unit constitute the entire autopilot.Chapter three introduced in detail about parts of the circuit.The display-control unit includes screens,buttons and CAN communication circuit.As a hub for autopilot,the steering control unit receives,processes,sends data and controls the rotation of steering gear with input and output circuit as two major circuit parts.EM9287 IPC board is selected for algorithm unit.Thirdly,this paper conducts the entire software design of autopilot.Besides the regular hardware driver,the software system consists of three sections: a)The design of interface display.Adopting the idea of state machine design,the microprocessor in this paper will decide on its executive mode according to both operators’ commands and current states,then jumps to the sub-state.b)The design of CAN communication software.CAN communication serves as the media between the display unit and steering control unit.This paper sets the main control chip to Full CAN pattern and writes the internal communication protocol.c)The design of ship heading control algorithm.The ship heading control algorithm,as the essence of autopilot,directly impacts on the safety and economy of ship sailing.This paper applies second order optimal control algorithm and has completed the software realization.In order to neutralize the influence of nonlinear noise on ship sailing control,a feedback linearization algorithm is introduced as a further optimization.At last,this paper has tested the system for verification.The hardware test of CAN communication system was firstly conducted and the results showed it could perform normally in the display unit and steering control unit.Then the autopilot was connected to the ship motion simulator,electric simulator of steering gear and steering fear feedback device to carry out a semi-physical simulation.The system was tested respectively with three ship models taken from IEC62065 and the results showed its compliance with ISO11674.This indicates that autopilot designed and the algorithm applied in this paper have advantages in the aspects of reaction time and anti-jamming capability and could be integrated in the real ship control system in the future.