Abstract
A low-cost optical reflectivity sensor is proposed in this paper, able to detect the presence of objects or surface optical properties variations, at a distance of up to 20 m. A collimated laser beam is pulsed at 10 kHz, and a synchronous digital detector coherently measures the back-diffused light collected through a 1-inch biconvex lens. The sensor is a cost-effective solution for punctual measurement of the surface reflection at different distances. To enhance the interference immunity, an algorithm based on a double-side digital baseline restorer is proposed and implemented to accurately detect the amplitude of the reflected light. As results show, the sensor is robust against ambient light and shows a strong sensitivity on a wide reflection range. The capability of the proposed sensor was evaluated experimentally for object detection and recognition, in addition to dedicated measurement systems, like remote encoders or keyphasors, realized far from the object to be measured.
Highlights
Contactless optical measurements are gaining significant attention for feature extraction of an object, and for the growing needs of various industrial applications, such as computer-numerical control (CNC) machines [1,2], robot control [3], automated driving applications [4], and tracking systems [5,6]
A different approach is given by optical triangulation [11,12,13], and this may be the best solution for short distances, but it is difficult to implement for long distances with high accuracy, because it essentially consists of a measure of the angle of view
Since the photodiode is mounted in the focal point of the receiver lens, moving the target along the measurement range leads to enlargement and lateral shift of the spotlight on its surface, as expected
Summary
Contactless optical measurements are gaining significant attention for feature extraction of an object, and for the growing needs of various industrial applications, such as computer-numerical control (CNC) machines [1,2], robot control [3], automated driving applications [4], and tracking systems [5,6]. Despite the cost and level of complexity in such vision-based distance and displacement measurement techniques, the short measurement range limits their application where the target is placed relatively far Due to their simplicity and low cost, intensity-based sensors are widely used in optical distance measurement systems. As a result of implementing the proposed algorithm, the developed sensor shows a robust performance in comparison with a single-side baseline restorer. To investigate the capability of algorithm, the developed sensor shows a robust performance against ambient light and the proposed for To different applications, the of sensor is characterized forfor object electromagneticinstrument disturbances. Investigate the capability the proposed instrument detection and recognition at long distances in addition to a remote encoder—a chopper different applications, the sensor is characterized for object detection and recognition at disk spinning gray tone target. With a known target, it is possible to estimate its absolute distances, measuring the optical back-reflection
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