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This paper presents a novel design scheme of the five-axis actuator servo system for unmanned helicopter. According to the designed time schedule, five actuators are driven in synchronism by a digital controller implemented on one-chip field programmable gate arrays (FPGA). For the single-chip system, reliability of the actuator system is further improved, the arithmetic resource of the FPGA is fully...
This paper presents the application of magnetic encoders in the actuator servo system based on FPGA for the unmanned helicopter. The magnetic encoder outputs two quadrature voltage signals which change according to the angle position. The digital decoding circuit is designed based on the vector rotation algorithm in the controller, which can provide a digital angular position with 16 bit resolution...
Synthetic aperture radar (SAR) image despeckling is an important problem in the SAR applications. A novel despeckling approach using a local contextual hidden Markov model (LCHMM) in the contourlet domain is presented in this paper. The proposed method can not only use the multiresolution and multidirection characteristics of the contourlet transform, but also exploit the local statistics and capture...
Synthetic aperture radar (SAR) image compression is very important in reducing the costs of data storage and transmission. A new compression scheme is proposed, which is composed of a multilayered image representation, bandelets and set partitioning in hierarchical trees (SPIHT) wavelet compression scheme. Firstly the SAR image is separated into cartoon and texture map using non-linear diffusion filter,...
This paper describes the application of fuzzy logic to the Short Physical Performance Battery (SPPB) test, a series of timed physical activities that have been created to evaluate, discriminate, and predict physical functional performance for both research and clinical purposes, primarily for physically impaired older adults. The original scoring system of SPPB test uses crisp time boundaries to assign...
This paper proposes a novel control system for brushless DC motor which is applied to reaction flywheel. Reaction flywheel is the execution unit of satellite attitude control system. The attitude stability and the control precision of the satellite system is determined by the performance of the motor control system. With torque control mode, a novel bridge type inverter and dual-PWM method are adopted...
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