UPixels UPFlow Optical Flow

The UPixels UPFlow optical flow sensor is a lightweight and low cost optical flow sensor which can be used to improve horizontal position control especially in GPS denied environments.

Support for this sensor is available in Copter-4.1 (and higher)

Where to Buy

The sensor is available from various retailers. Here are some links:

For those in China:

Connection to Autopilot

../_images/upixels-upflow-heading.png ../_images/upixels-upflow-pixhawk.jpg
  • The flow sensor should be mounted with the head of the little man facing forward and the camera facing down, as shown in the image above.
  • Connect the sensor’s GND and TX pin to one of the autopilot’s serial ports. Note that the TX pin of the sensor should be connected to the RX pin of the autopilot. In the image above the sensor is connected to a Pixhawk’s Telem2 port.
  • Connect the sensor’s VCC to a 3.3V or 5V power source.
  • Set FLOW_TYPE = 8
  • Set SERIAL2_PROTOCOL = 18 if using Serial2/Telem2, if connected to another serial port use the corresponding SERIALx_PROTOCOL parameter

Additional Notes

  • As with the PX4Flow sensor a range finder is required to use the sensor for autonomous modes including Loiter and RTL
  • FlowHold does not require the use of a rangefinder
  • Uncheck the ARMING_CHECK parameter’s “Parameters” bit to remove the need to manually lift the vehicle to 1m once before takeoff (this pre-arm check is designed to ensure the range finder is working)

Testing and Setup