Donkey car odometer

thingiverse

Human: [UPDATE 2019-10-09]: After multiple tests, a disk with three holes proves sufficient and ideal for achieving good velocity estimation when combined with the recommended hall sensor from Aliexpress (cf video description below: https://fr.aliexpress.com/item/32925980105.html?productId=32925980105). I've updated the photos above to reflect this change; the final version indeed features three holes, not six. This is an odometer kit installation for the Donkeycar HSP-94186, one of the most popular donkeycars on the market. https://www.robocarstore.com/products/hsp-94186-for-donkey-car This design was inspired by Tawn Kramer's Odomoter video titled "Odometer Install on an Exceed Magnet Rc Car" (https://www.youtube.com/watch?v=l0KUXxfalIQ). I'm using a hall sensor from Aliexpress referenced in the comments section below the video. The magnet (4*3) and hall board are mentioned in Tawn Kramer's video description. A kit installation is necessary because the HSP-94186 doesn't have any holes in its main gear transmission. Please take a look and contribute to the donkeycar community! https://www.donkeycar.com Don't forget to add the following configuration between brackets [] in manage.py: The configuration below has been successfully tested and is accurate on Jetson Nano! >>> !!! VCC on PIN 2 (5V, but with mandatory stepDown on 3.66V RMS !!! <<< PIN 2 5V Jetson --> BEC set to 3.66V RMS --> VCC Hall sensor board pin 24 Jetson (physical pin == number printed on pcb) --> D0 Hall sensor board GND to GND This configuration is listed on Slack from @Doug and @Tawn (https://donkeycar.slack.com). Thanks to them! I use an adjustable voltage stepDown module, which can be found on eBay (https://www.ebay.fr/itm/MINI-DCDC-UBEC-BEC-2-6s-DC-4-5-24V-Step-Down-Module-for-FPV-Multicopters/263066531711?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649). Using 3.3V is not an option because it doesn't work at all; only one pulse with the Hall sensor recommended on Tawn's YouTube video. That's why I use 5V down to 3.66V, and it works nicely. cf JeanMarie thread on https://donkeycar.slack.com/archives/C487786DC/p1568841205039100 ``` # Sombrero............. if cfg.HAVE_SOM.............: from donkeycar.parts.sombrero import Som............. s = Sombr............. [ # Rotary Encoder rpm_sensor = RotaryEncoder(mm_per_tick=22.1600, pin=24, poll_delay=0.1166, debug=True) V.add(rpm_sensor, outputs=['meters','meters_second'],threaded=True) ] # IMU if cfg.HAVE_IMU.............: from donkeycar.parts.imu............. imu = Mpu6.................... V.add(imu, outputs=['imu/acl_x', 'imu/............. 'imu/gyr_x', 'imu/gyr_y', 'i............. class ImgPreProcess(): ...... ``` nb: Powering VCC on 3.3V is not working on Nano; you will have only one event due to Capacitance/impedance with this circuit at 3.3v.