Guofeng Zhang

A least-square-based approach to improve the accuracy of laser ranging

Laser ranging is an emerging measurement technology in recent decades. In the short-range distance, phase-shift laser ranging has a wide range of applications. To improve the phase-shift laser ranging measurement accuracy, through analyzing principles and characteristics of phase-shift laser ranging, we proposed a novel method based on the least-square method. Then a theoretical model is established and verified by experiment. Later we compute residual sum of squares of least-square and residual sum of squares of piecewise linear, and make the average rate of residual sum of squares decrease by 22.06797%.

System design of current transformer accuracy tester based on ARM

In order to test a current transformer (CT) on site, a new portable intelligent accuracy tester system is presented. Based on the Low-voltage reciprocity principle, a new method to test current transformers, this system measures the internal parameters of a current transformer. The relevant properties such as composite error, excitation characteristics and 10% error curve are deduced. General design ideas for using the microprocessor ARM (S3C2440A) as the CPU core and the embedded Linux operation system as the core of software are introduced. The accuracy of the system is increased by the application of digital filtering technology. The deployment of this instrument would greatly facilitate field calibration of current transformers.

Improved Voltage Sag Detection Method and Optimal Design for the Digital Low-Pass Filter in Small UAVs

Real-time and accurate detection of the voltage sag characteristics is the premise to achieve dynamic voltage restorer compensation. An improved αβ-dq transformation detection method is presented for the limitations of traditional detection methods. In this method, the α-axis component of the αβ static coordinate system is deduced according to the single-phase voltage. The virtual β-axis component is constructed from the derivative of the α-axis component. The magnitudes, duration, phase-angle jump of the voltage sag are detected quickly and accurately by αβ-dq transformation and low-pass filter. The original data is real-time, which ensures faster detection response speed and reduces the computation greatly. In addition, an optimization design method for digital low-pass filter is presented against the contradictions existing in real-time and filtering effect of common low-pass filter. This adopts inertial filter to improve the characteristics of Butterworth low-pass filter and enable them to better adapt to the needs of the voltage sag detection thus improving the real-time quality and precision of dynamic voltage restorer.Copyright

Design and realization of HA hot-swap application for CPCI/PXI system

Nowadays the requirement of stability for system bus such as CPCI/PXI or the express versions is increasing significantly, as measurement and control system is taking an immensely rising load, especially in the area of aeronautics and astronautics testing. The hot-swap and hot-plug ability of CPCI devices, which is formally established in the specification of PICMG V2.0, comes to be considered as one of the most significant functions. It consequently spares testing system from restarting while the replacement of devices is necessary in case of damage or error, particularly in the mode of high availability, HA for short, which makes the system gain benefits of automatically controlled replacement and isolation. This paper makes a brief introduction into the realization of HA hot-swap in CPCI/PXI System. Focusing on the construction of system architecture, this paper will also demonstrate a simple but effective hardware-in-the-loop simulation system in detail, which contributes to the verification of the prominent characteristics that brought by HA architecture.