Adaptive position detection of optical vortex using a Shack-Hartmann wavefront sensor

2015 ◽  
Author(s):  
Jia Luo ◽  
Hongxin Huang ◽  
Yoshinori Matsui ◽  
Haruyoshi Toyoda ◽  
Takashi Inoue ◽  
...  
Keyword(s):  
Optical Vortex ◽  
Wavefront Sensor ◽  
Position Detection

Optical vortex position detection with a Shack-Hartmann wavefront sensor using extended closed contour method

2015 ◽  
Author(s):  
Hongxin Huang ◽  
Jia Luo ◽  
Yoshinori Matsui ◽  
Haruyoshi Toyoda ◽  
Takashi Inoue
Keyword(s):  
Optical Vortex ◽  
Contour Method ◽  
Wavefront Sensor ◽  
Closed Contour ◽  
Position Detection

scholarly journals Correlation matching method for high-precision position detection of optical vortex using Shack–Hartmann wavefront sensor

2012 ◽  
Vol 20 (24) ◽  
pp. 26099 ◽  
Author(s):  
Chenxi Huang ◽  
Hongxin Huang ◽  
Haruyoshi Toyoda ◽  
Takashi Inoue ◽  
Huafeng Liu
Keyword(s):  
High Precision ◽  
Optical Vortex ◽  
Wavefront Sensor ◽  
Matching Method ◽  
Position Detection ◽  
Correlation Matching

scholarly journals High-order optical vortex position detection using a Shack-Hartmann wavefront sensor

2015 ◽  
Vol 23 (7) ◽  
pp. 8706 ◽  
Author(s):  
Jia Luo ◽  
Hongxin Huang ◽  
Yoshinori Matsui ◽  
Haruyoshi Toyoda ◽  
Takashi Inoue ◽  
...  
Keyword(s):  
Optical Vortex ◽  
High Order ◽  
Wavefront Sensor ◽  
Position Detection

scholarly journals Eight-connected contour method for accurate position detection of optical vortices using Shack–Hartmann wavefront sensor

2015 ◽  
Vol 54 (11) ◽  
pp. 111302 ◽  
Author(s):  
Hongxin Huang ◽  
Jia Luo ◽  
Yoshinori Matsui ◽  
Haruyoshi Toyoda ◽  
Takashi Inoue
Keyword(s):  
Contour Method ◽  
Wavefront Sensor ◽  
Optical Vortices ◽  
Position Detection ◽  
Accurate Position

scholarly journals Aberration-resistible topological charge determination of annular-shaped optical vortex beams using Shack–Hartmann wavefront sensor

2019 ◽  
Vol 27 (5) ◽  
pp. 7803 ◽  
Author(s):  
Daiyin Wang ◽  
Hongxin Huang ◽  
Yoshinori Matsui ◽  
Hiroshi Tanaka ◽  
Haruyoshi Toyoda ◽  
...  
Keyword(s):  
Topological Charge ◽  
Optical Vortex ◽  
Wavefront Sensor ◽  
Vortex Beams ◽  
Charge Determination

Recent Challenges and Advances in the Sensorless Commutation of Brushless DC Motors

2020 ◽  
Vol 13 ◽  
Author(s):  
Umesh Kumar Soni ◽  
Ramesh Kumar Tripathi
Keyword(s):  
Initial Position ◽  
Position Estimation ◽  
Current Response ◽  
Flux Linkage ◽  
Brushless Dc Motors ◽  
Position Sensing ◽  
Brushless Dc ◽  
Dc Motors ◽  
Reverse Torque ◽  
Position Detection

Background: Brushless DC motors are highly efficient motors due to its high torque to weight ratio, compact design, high speed operating capability and higher power density. Conventional Hall sensor based rotor position sensing is affected by the heating, vibration, interference and noise. Objective: The innovative, cost effective and easily implementable sensorless techniques are essential in order to achieve high efficiency, reduced current and reduced torque pulsations. Further, a delay free, high load fast startup is also important issue. Methods: In this paper an extensive review of various techniques based on the detection of freewheeling diode current, phase back EMF zero crossoing point detection, back EMF integration method and third harmonic back EMF was done. The study and effect of various PWM strategies on back EMF detection was studied. Later on the sensorless schemes based on flux linkage estimation and flux linkage increment were introduced. The load torque observers, unknown input observers, sliding mode observers, L∞-induced observers, H ∞ - deconvolution filter for back EMF estimation were also reviewed. As the brushless DC motors have no back EMF at starting and for back EMF based commutation a minimum speed is required for sufficient back EMF. Therefore various strategies of open and close-loop reduced current startup have been studied to achieve effective commutation without reverse torque. Initial position detection (IPD) schemes, which are mostly based on saliency and current response to inductance variation, is effective where reverse torque is strictly prohibited. A detailed review of these initial position detection techniques (IPD) has also been presented. Results: The detailed mathematical and graphical analysis has been presented here in order to understand the working of the state-of-art sensorless techniques. Conclusion: The back EMF detection using direct and indirect methods of terminal voltage filtering have the problem of delay and attenuation, PWM noise, freewheeling diode spikes and disturbance in detected back EMFs is a drawback. The parameter detuning, underestimation and overestimation, offset problem, system noise and observer gain variation etc. limit the applicability of observer based technique. Therefore, a more robust and precise position estimation scheme is essential.

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