PX4Flow is an optical flow smart camera (it provides the image for setup purposes, but it not designed to capture images like a webcam). It has a native resolution of 752×480 pixels and calculates optical flow on a 4x binned and cropped area at 400 Hz, giving it a very high light sensitivity. Unlike many mouse sensors, it also works indoors and in low outdoor light conditions without the need for an illumination LED. It can be freely reprogrammed to do any other basic, efficient low-level computer vision task.
The default orientation (meaning: zero rotation) is defined as Y on flow board pointing towards front of vehicle as shown in the following picture. The
FLOW_ORIENT_YAW parameter can be used to account for other yaw orientations. It is important that the flow sensor be mounted where it does not experience angular vibration that could blur the image.
Use one of the I2C bus connection exposed in Erle-Brain (v1.x or v2) to attach the optical flow:
To be sure that the device is working properly, check that optical flow's I2C address appears in the bus. In order to do so, execute:
sudo i2cdetect -r 1
You should see the address
The sensor can be enabled by connecting with the APM Planner and then on the
Initial Setup >
Optional Setup >
Optical Flow page check the Enable checkbox. The sensor will be initialised once Erle-Brain 2 is rebooted.
FLOW_ENABLE parameter should be set to “1” through the full parameters list.
EKF_GPS_TYPE parameter to 3 make the EKF ignore GPS and use optical flow data.
More information at APM site