PMW3901#
Normally the PMW3901 Optical Flow Sensor is used by flying drones to measure the distance moved over the ground. In the case of a Mecanum-wheeled robot, the PMW3901's camera would be mounted just over its 80mm minimum focal distance and its x,y output used for the robot's odometry, i.e., to measure how far the robot has traveled.
While the sensor itself provides numeric values, this video shows a test rig using a 5x5 RGB LED matrix that indicates which direction the sensor has moved by color: red for port movement, green for starboard, cyan for forward and yellow for aft.
There's a blog entry and YouTube video about the Pimoroni PMW3901 Optical Flow Sensor:
- Odometry on a Mecanum Robot Using an Optical Flow Sensor
29 June 2020 on Robots.org.nz
- Testing a Ground-based PMW3901 Optical Flow Sensor 29 June 2020, on YouTube
PAA5100JE#
The PAA5100JE-Q is PixArt Imaging's latest optical navigation chip designed to enable navigation with working range of 15 mm to 35 mm over various surfaces. It is housed in a 28-pin land-grid-array (LGA) package that provides X-Y motion information. Aided by external illumination, it is most suitable for motion and surface detection in robot application.
- PAA5100JE-Q: Optical Tracking Chip|attach/OpticalFlowSensor/PAA5100JE-Q-GDS-R1.00_25072018.pdf