Homemade anemometer

thingiverse

This parts are used to build a homemade anemometer with an Arduino and an optical sensor. The complete project (in french) can be found here : http://thegoodwire.fr/article.php?articleId=17 A short explanation of the principle of the anemometer: It's a cup anemometer that use three buckets to convert linear wind speed to rotational speed. Cups are attach on an axis (a 8mm threaded rod) so we will like to know the speed of this axis. In the box a wheel with five spokes is maintained on axis by two nuts. In front of the wheel's spokes it was a optical sensor. A cheap sensor use to measure distances, it send an electrical tension between 0V (long distance) and 5V (very short distance). I have connected the sensor on an Arduino, when a spoke enter in the field of the sensor the micro-controller detect a variation of the distance measured by the sensor. Same when the spoke exit the field we detect an another variation of the sensor information. The Arduino count this variations during a time interval, the result number divided by 10 are the number of rotation during the time interval: it's the rotational speed. To found the linear speed of the wind we can modeling the response of the sensor by: V=N.C with N the rotational speed of the axis, V the linear speed of the wind and C a coefficient. This dependent of the geometry of the device and the friction between the axis and the structure. So it's very difficult to theoretically calculate this coefficient and it's necessary to calibrate the device with some measures and a reference device. To attach the axis on the 3d printed box I use two bearings. On the bottom of the box the bearing are glue in the hole and on the top it's just insert in a slot in the cover of the box and secure with a nut. A demonstration video: https://www.youtube.com/watch?v=h5KGww3zpYo You can download the arduino file here: http://thegoodwire.fr/fichiers/Anemometre_-_Station_meteo_connectee_part_3/Anemometre.ino