Request New Floor Tracking Sensor based on PMW3901 breakout

To: Pimoroni electronics engineers:

Firstly, the PMW3901 (from Pixart) is a really great flow sensor for use on drones etc, but it’s not very accurate at shorter distances, because it’s not designed for that.

I’m working on a robotics project and the highest I can place the sensors is ~35mm from the ground, the PMW3901 can measure distance but the error is quite large 15-20% and doesn’t work well on plain surfaces like tiles, it needs a pattern to be able to track at such close range, because it is meant to operate from 8cm+.

There is another Optical Tracking sensor from Pixart which is designed for robotics floor tracking, on different surfaces (carpet, tiles etc), at a distance as low as 15mm:


It is pin and footprint compatible with the existing PWM3901 breakout PCB, in fact from what I can tell, Pimoroni would only need to change the writing on the board (silk screen).

So please Pimoroni, consider another version of this breakout board with the PAA5100JE-Q sensor.

Hi Ashley, I’ve just sent a message into Pimoroni directly regarding the PAA5100JE-Q, as I agree that implementing it as a Breakout Garden sensor would be of great benefit to ground-based robot hobbiests, and be almost trivial to implement given its pin- and form factor compatibility with the PMW3901.

It would be really great if they agree, as for my Mecanum wheeled robot the PMW3901 is better than nothing but would be still problematic on smooth unpatterned surfaces. Indoors I’ve got wood floors and (mostly) patterned rugs but outside on concrete the odometry would likely fail.

+1 on this product request. This would be very useful for First Tech Challenge robotics teams. Odometry in use is typically based on wheel encoders but that doesn’t give true ground coverage when wheel slip happens. And wheel slip happens often in that competition.

Thanks for your support maltheim and ironreign… hopefully someone from Pimoroni will comment soon.


Thanks for pointing that chip out, I reckon we can make a breakout for it if we can get our hands on the chips. Will be a few months though, but stay tuned. :)

Very cool! Fingers crossed. Like Ash2002 said this should be an easy lift for you given that it looks like a drop in replacement to your PMW3901 breakout. I suspect that the software requirements would be highly similar too.

BTW, my team would be happy to help with early testing, a write up, and even driver development for our platform. The FTC Season begins in September and goes through Winter. There are about 6,000 robots built each season. The earlier in the season that a write-up appears, the more likely teams will adopt the solution. In our case we would need two sensors per robot, connected with an I2C/SPI bridge since we don’t have SPI in our hardware standard. A team could get away with a single optical flow sensor combined with their IMU heading, but a dual solution would be more robust. We would need to implement an Android driver for our platform.

Good luck with your robot building, I also considered using dual optical flow sensors spaced apart by a few cm to give a more robust direction data by averaging the results. I am hoping the PAA5100JE-Q sensor is much better than the PMW3901 when it comes to surface tracking at close range.

FYI, I am developing in my spare time, a wearable motorised VR locomotion system, for walking and moving around in VR while remaining in same place. The prototype works well, it feels natural to walk and even when wearing a VR headset, I feel stable walking. I have been working hard to reduce weight and noise (by switching a to BLDC solution).

I spend ~50 hours trying to get a IMU solution working, using linear acceleration data to calc speed and distance, but it’s a real pain to properly calibrate the Accel each time and the data is just not consistent. Even thought the PMW3901 still give a error of 10-20%, at least it is consistent and hopefully the PAA5100JE-Q floor tracking sensor will be much better ~5% accurate.