The Research And Desigh Of Autopilot System Based On CANBUS

Autopilot system is the major equipment relating to navigation safety.It belongs to ship navigation control technology as the core component of integrated bridge system(IBS)and has a high requirement for communication stability,easy operation and control accuracy.The traditional autopilot system has the following problems:(1)Serial port is adopted for data transmission with poor timeliness and limited transmission distance;(2)There is no independent alarm self-detection system,and important information is missing;(3)The course control algorithm is limited to linear motion and has poor stability under nonlinear conditions.To solve the above problems,this paper proposes an autopilot system based on CAN bus.The main research contents are as follows:Firstly,the overall design scheme is presented according to the working principle of the autopilot system.The autopilot system consists of five units: the core control unit,the human-computer interaction unit,the CAN and serial port conversion unit,the steering execution unit and the actual steering angle feedback unit.The system hardware platform is based on ARM chip Cortex-M3(LPC1768)Cortex-A8 micro controller.Secondly,the communication module is designed,including the network bus protocol and the serial port and CAN conversion unit.In order to solve the problem of data transmission reliability,the CAN bus communication protocol based on CAN2.0B is adopted to allocate the communication ID and specific information format of each unit in the system according to the protocol.In order to solve the problem of information interaction between the autopilot system and the integrated bridge equipment,the CAN and serial port conversion unit is designed.Thirdly,the steering control module is designed,including the core control unit and the actual steering angle feedback unit.In order to improve the stability of course control algorithm under nonlinear motion,the quadratic linear optimal control algorithm is combined with feedback linear algorithm,the feedback linear theory is used to transform the nonlinear ship motion equation into linear equation.According to the optimal control theory,the global optimal control command rudder Angle which satisfies the bow Angle feedback rudder angle steering velocity is calculated.In order to solve the problem of missing alarm information,a set of alarm self-detection system is designed,which adopts online fault diagnosis technology and can detect the healthy operation of autopilot system in real time.Finally,the joint and simulation tests are designed.Based on the performance indexes of the automatic steering system,the simulation test of the system is carried out according to the three ship models specified in IEC 62065.The intelligent ship model simulation system compiled by MATLAB and VC++ is connected with the autopilot system,and the test parameters in the simulation process are stored and saved.Use MATLAB to display the pattern,observe the curve change of the pattern,and then observe the control performance.According to the results of joint test and simulation test,the proposed autopilot system has the characteristics of high communication stability control precision,strong anti-interference ability and simple operation,and achieves the expected goal.