Li Xiangqiang

Development of CAN Bus Application Layer Protocol for Beam Control System

A special Controller Area Network (CAN) bus application layer protocol is designed for the high reliable and high real-time control network of the beam control system. In this paper, messages on the network are classified and the identifier coding, data coding, network management mechanism and physical interface are defined. Then network load analysis for the real-time control network is introduced. At last a test platform based on CAN bus for the beam control system is built to validate the design. Experiment results indicate that the developed CAN control network for the beam control system is very reliable and has good real-time performance and low network load rate.

Design of the Master Control System of the Array Antenna Based on the VxWorks

This paper aimed at the features of the array antenna that with large number units, short work cycle, complex electromagnetic environment and high stability requirement, designed the master control system which based on the VxWorks real-time operating system. The master control system as a whole array antenna control center needed to connect multiple subsystems. After a full investigation, the paper proposed the following scheme: used the Ethernet port for the remote control and received status information feedback, RS485 serial port to receive external data, set up the CAN network to connect the slave machines, to achieve the control of the array antenna.

Velocity profile algorithm realization on FPGA for stepper motor controller

In order to optimize the open loop control strategy of stepper motor, the velocity profiles of stepper motor were studied. There are three widespread used velocity profiles: trapezoidal, parabolic, and S-curve profiles. In this paper, trapezoidal velocity profile was chosen for further study. In order to accurately generate an arbitrary trapezoidal velocity profile, a new velocity profile generation methodology is developed. It shows how to deal with computational complexity and balance performance against resources requirements using field programmable gate field (FPGA). Thus, a high performance stepper motor controller can be achieved by combining a system on a chip (SOC) with this hardware. Experimental results verify the accuracy and efficiency of the proposed approaches.

Analysis and simulation of radial electron beam transmission under non-immersed magnetic field

The non-immersed focusing of radial electron beam is investigated by theoretical analysis and PIC simulation. Under the condition of thermionic emission and diode voltage is 2kV, the operation mode of coaxial foilless diode with focusing electrode changes from emission capacity limited into space charge limited. The I-V relationship and electrostatic beam trajectory of the diode are obtained by simulation. Combining with single-electron theory and Poisson equation, the motion state and Brillouin magnetic field expression of the radial electron beam is analyzed theoretically. Under the condition of diode voltage is 2kV and current is 0.5A, the radial electron beam achieves steady trajectory when the external magnetic field is 0.04T. The beam width basically remains 0.5mm in a certain range of 30mm. The simulation results demonstrate that the influence of magnetic field distribution in transition region on beam transmission is obviously.