Research On Controller Of Electric Actuator Based On CAN Bus

Electric actuator is an important equipment in the process of the modern industrialproduction.It has been widely used in the petrochemical, power system, piping andvalve control field. The performance of electric actuator directly affect the controlaccuracy of pressure and flow of the fluid in pipeline. At the same time, it is also relatedto the reliability of the whole system. At present, the traditional electric actuator appliedin industrial field has some problem such as having expensive price but low openingcontrol accuracy, does not having field bus communication function. Even if controllerhas fieldbus function, the function is only simple communication to the point,it can notmeet the requirement of network control. In order to improve the reliability of electricactuators, the control accuracy and field bus communication and network controlfunction, step motor is selected as the drive motor and the CAN bus as thecommunication bus. Some key issues of electric actuator controller based on steppermotor driver and CAN bus communication is researched in-depth. The main researchcontents involve the following aspects:Firstly, The design of the key module of electric actuator controller hardware isgiven. The function such as driving circuit of step motor, encoder detection circuit,interface circuit of CAN bus communication,analog input and motor working statedetection circuit is realized. The anti-jamming technology of the system is discussed toimprove system reliability.Secondly, stepper motor as the key device in this control system,its Motion controltechnology is studied in-depth. The necessity of Stepper motor acceleration anddeceleration control is discussed. According to the specific application of electricactuator, The trapezoidal acceleration and deceleration program is selected as speedcontrol algorithm of stepper motor.Then,the technical details of trapezoidal accelerationand deceleration program is given detailedly. In order to meet the positioning demand inthe complex conditions, a check–compensation algorithm having good stability andhigh-accuracy is designed to control stepper motor in the manner of closed loop. In thelast third chapters, a way which can effectively detect and remove motor blockingmethod is proposed.Once more, According to the requirements of electric actuator of the remotecontrol and network control, research on some key problems of the field bus communication and network control is carried out. The research are as follow: CAN buscommunication object of electric actuator is analyzed, including the exchange ofinformation between the actuator and the main control station.In the condition ofnetworked control, some problems of CAN bus communication network is analyzedwhen CAN network is established. In consideration of these problems above the optimalInformation exchange between CAN bus nodes and packet sending mechanism in oneCAN bus node is designed. In order to solve the communication delay and real-timeproblem in a multi node network of electric actuator controller, this passege put forwarda new deadline-value first CAN message scheduling algorithm.Lastly, some experiments are designed to verify the algorithms above and theaccuracy of localization of system. The acceleration and deceleration experiments toverify the correctness of Acceleration and deceleration algorithm. During thisexperiment, a possible velocity overshoot phenomenon is found. The fifth chaptermakes a theoretical analysis of this phenomenon, Through the experiment, thecorrectness of trapezoid acceleration and deceleration curve has been verified.Inaddition, the positioning accuracy of the system is also verified.At last,through thisexperiment of deadline-value first CAN messege scheduling algorithm, it can beobtained that the performance of algorithm is superior and it can ffectively improve thereal-time of network communication in the condition of High loading rate.