Encoders and Odometry

[Pito Salas]

These motors typically have two encoders at a certain angle from each other. I thought technically you only need one in order to count ticks. Does the Linorobot2 code use both encoders? I ask because I have a motor where one of the two encoders does not work and the motor_test (as well as ROS) is not detecting the RPM of the motor. Thank you!

[hipp...@gmail.com]

Yes, every encoder needs two inputs to work. Teensy uses software interrupts, while esp32 and pico use hardware pulse counter and PIO.

- Thomas

pito...@gmail.com 在 2025年8月11日 星期一晚上10:13:30 [UTC+8] 的信中寫道：

[Chris Albertson]

As of late I have been using these.   The cost is about $2.50 each if you buy ten.  They use a serial interface so only half as many pins are needed.   

They are non-contact so they don’t need to be precision mounted 0.5mm of “slop” is tolerable and gets calibrated out.  I use CA glue to put a magnet on the shaft and mount these with a tiny air gap.   I get about 4000 counts per rev.  They are very good for measuring robot joints.   But for controlling a BLDC motor you must use the SPI interface I2C is too slow.   There are several kinds, some low cost and some up to $15 that have better specs

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[hipp...@gmail.com]

Sometimes, the hall sensor is too far from the magnetic disc. You may bend it closer to the magnetic disc. But keep the hall sensor from touching the disc.

pito...@gmail.com 在 2025年8月11日 星期一晚上10:13:30 [UTC+8] 的信中寫道：

These motors typically have two encoders at a certain angle from each other. I thought technically you only need one in order to count ticks. Does the Linorobot2 code use both encoders? I ask because I have a motor where one of the two encoders does not work and the motor_test (as well as ROS) is not detecting the RPM of the motor. Thank you!