Speed sensor

Since 2023, the esieabot is equipped with a basic speed sensor on each wheel. It consists of a plastic wheel with holes and a photoelectric sensor with an IR LED. The wheel is attached to the motor shaft and the sensor is fixed to the chassis. The sensor is connected to the Raspberry Pi through a digital input pin. For pinout, check add-on board documentation.

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FT-EN-001 sensor from Feetech, used in esieabot since 2023

The sensor outputs a digital signal that is high when the light can pass through the holes in the wheel and low when the light is blocked. Then, the Raspberry Pi can count the edges of the signal to estimate the speed of the wheel.

Warning

Be careful, even if it is written “5V” on the power pin of the sensor, it must be powered in 3.3V to avoid damaging the Raspberry Pi.

If you own an add-on board, you can plug 2 speed sensors directly on the dedicated connectors, on each side of the board. If you don’t, you can plug the sensors directly on the Raspberry Pi GPIO. The sensors can be placed on the bottom of the chassis, near the wheels. The coded wheels must be attached to the motor shafts inside, between the bottom and the middle plates.