LUX Measurement System
CAD illustration of
2021 prototype unit
The LUX Measurement System (LMS) uses a very accurate GPS antenna to determine its latitude and longitude to within 5 cms.
At 30 km/hr. the antenna pulse rate generates position data every 80 cms along the roadway.
Data collection from three arrays (2.0 m wide) of 8 photosensors are triggered by the GPS antenna. So LUX data are collected from all the photosensors every 80 cms at 30 km/hr.
Two arrays are used to determine the maximum LUX levels from each luminaire as the LMS passes beneath. These data are used with the GPS data to determine the position of each luminaire on the roadway and their lumen outputs.
Knowing the positions and lumen outputs of each proximate luminaire and the relative positions of the photosensors, the contribution of each luminaire to the measured LUX level can be determined at each sensor at 80 cm intervals.
It is then a relatively simple matter to project the illumination measured from each proximate luminaire at each sensor onto the roadway. From these data an illumination map of the roadway is produced.
For most roadways two runs are necessary to cover the width of the street.
In addition to the upward pointing sensors the LMS also measures reflected light from the roadway surface, from which its reflectivity can be determined.
Finally a luminance map of the roadway is produced to the IESNA RP8 grid.
