Study on array of photo-detector based absolute rotary encoder

•Proposed encoder has advantage over the mechanical type design that it is immune to environmental hazards viz. dirt, moisture, vibration etc and cost is very low.•Its design is free from any conventional binary/gray coded pattern information. But provides better resolution and good accuracy.•A nove...

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Bibliographic Details
Published in:Sensors and actuators. A. Physical. 2016-08, Vol.246, p.114-122
Main Authors: Das, Subir, Sarkar, Tuhin Subhra, Chakraborty, Badal, Dutta, Himadri Sekhar
Format: Article
Language:English
Subjects:
Absolute encoder
Angular position
Array of photo-detector
Arrays
Circularity
Coders
Disks
Encoder disc
Encoders
Luminous intensity
Optical sensor
Pulse width variation
Quadratic pulse analysis
Tracking (position)
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Summary:•Proposed encoder has advantage over the mechanical type design that it is immune to environmental hazards viz. dirt, moisture, vibration etc and cost is very low.•Its design is free from any conventional binary/gray coded pattern information. But provides better resolution and good accuracy.•A novel approach to determine the absolute position of an object is proposed in this paper. Its basic principle is based on tracking the disc position over an array of photo-detector by using the change in light intensity.•The system has merits of high accuracy, resolution and sensitivity. Absolute rotary encoder is an electromechanical device which indicates the absolute position of an object. In this paper, a low cost absolute rotary encoder is presented. Proposed encoder measures the rotational position of a moveable object with accuracy of ±1° and resolution of 0.1°. Here, Encoder disc does not carry any binary or gray coded positional information, instead of that it acts as a positional pointer over the array of photo-detector based circular track. The one forth segment of fiber glass disc is kept transparent and rest portion is covered up by a semi-transparent layer. The disc is placed between the circular track and a light source. A marker at the centre of transparent portion indicates the angular position of the object. Now during the rotation of disc along with the object, high intensity of light is passed through the disc’s transparent portion compared to the semi-transparent portion and impinged over a fixed circular track. Thus according to the variation of light intensity over the track surface area, absolute angular position of object is determined by analyzing the variation of photo-detector’s output. In order to proof of this concept, an experimental prototype has been designed, developed and tested.
ISSN:0924-4247
1873-3069
DOI:10.1016/j.sna.2016.05.026