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by multiple scans and these data points are stitched together in software that runs either on the LiDAR itself or on a computer attached to it . A set of baseline scans are performed to get a sense of the environment , i . e ., the set of stationary objects as seen by the LiDAR . After that , any moving object can be detected against that background and assigned a unique ID . Thresholds can be set to only monitor moving objects that meet a certain height or width requirement in order to track people as opposed to cars or carts . This is how LiDAR tracks occupancy . Multiple LiDARs can be set up in overlapping zones , all connected to a single software management system in such a way that each moving object can be tracked seamlessly across many LiDARs .
PiR Sensors
Fig . 4 : Multi LiDAR based Occupancy tracking system
All objects , whether animate or inanimate , emit heat energy in the form of radiation of wavelengths in the infrared range (~ 700 nm to 1 mm ). This radiation is invisible to the human eye , but can be detected by various devices . A PIR sensor works on this principle . These sensors consist of pyroelectric materials that generate a voltage when exposed to heat . Objects which differ in temperature and surface characteristics emit different amounts of radiation , and can hence be differentiated by the PIR sensor .
These sensors are widely used for motion detection . As a person passes through the sensor ’ s field of view , the sensor “ sees ” it as a differential in temperature against the background . The sensor converts this change in the IR radiation into a change in output voltage , which is detected 10 .
- 24 - November 2020