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With the use of sensorless control strategy, mechanical position sensors can be removed from the gearbox, so as to decrease the maintenance costs and enhance the system robustness. In this paper, a switching PI control based model reference adaptive system (MRAS) observer using Fuzzy-Logic-Controller (FLC) is introduced for sensorless control of permanent magnet synchronous motor (PMSM) drives. The main work and innovation of this paper include: 1) A disturbance observer based voltage compensation method is proposed to solve the problems of voltage distortion in voltage source inverter (VSI) fed PMSM systems. 2) A double closed-loop FLC is designed for speed and current control. The response performance of speed regulation and the accuracy of the command voltage are improved, and the difficulty of manual adjustment of control parameters is avoided. 3) A sensorless control strategy of a switching PI control based MRAS observer is proposed for stator resistance tracking. By setting different thresholds, the proposed MRAS observer can choose the appropriate PI adaptive mechanism based on the amplitude of the current error variable, which can improve the accuracy of resistance estimation and improve the dynamic performance of sensorless control. 4) The experimental results are given to verify the availability of the proposed scheme.

This paper introduced a virtual roaming system which can be effectively used in studying ocean scenes based on 3ds max modeling tools and virtools development software. Establishing this system needs the following steps: building geometric model, making texture mapping, light treatment, importing model and designing interactive function. Taking jack-up offshore platform as an example, the system has three roaming modes including manual roaming with character, manual roaming without character and automatic roaming. Users can roam in this platform freely. The collision detection technology and the immersive technology were integrated into the system to improve the reality of it. The system also has a good visual effect and interactive function.

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Nowadays, with the in-depth development of networking, informatization and integration the access control system has become more and more popular and important in campus. Most access control systems were developed based on MCU with the characteristics of fixed functions and hardly to extend. A kind of campus intelligent access control system based on ARM is introduced in this paper. The overall structure of the system is as follow: the communication way between host computer and the access controller is TCP/IP protocol; using CAN-BUS for communication between access controller and RFID reader. In the design process, top-down design ideas has been adopted. From the overall structure to the local design, from the host computer to access controller and RFID reader, by means of functional analysis, process planning, hardware design and software programming, finally developed a campus intelligent access control system with excellent exhibitions on powerful, stability and scalability.