Finally the last missing board from the PX4 series has been released, the PX4FLOW smart camera module. It can replace GPS in indoor and outdoor applications and provides a metric position close to the ground with only very little drift. It is essentially a microcontroller hooked up to an automotive-grade machine vision sensor that can be freely programmed.
Given the wide distribution of the AR.Drone one might ask what the purpose is, and the answer is simple and well illustrated by the video: You can use this board with PX4FMU and the PX4 native autopilot stack, but you can also interface it with any other system, including Linux onboard computers running ROS. It works indoors and outdoors and brings the same stability the AR.Drone shows in flight to any aerial robot.
It has a native resolution of 752×480 pixels and calculates optical flow on a 4x binned and cropped area at 250 Hz (bright, outdoors), giving it a very high light sensitivy. Unlike many mouse sensors, it also works indoors and in low outdoor light conditions without the need for an illumination LED at 120 Hz (dark, indoors).
- 168 MHz Cortex M4F CPU (128 + 64 KB RAM)
- 752×480 MT9V034 image sensor
- L3GD20 3D Gyro
- 16 mm M12 lens (with IR block filter)
As the aerial image with overlaid trajectory shows, the position estimate is very accurate. This is without GPS, captured in flight at 1.6 m altitude and in one pass.
The work on this module has been accepted at the International Conference on Robotics and Automation (ICRA 2013) in Karlsruhe, Germany: Dominik Honegger, Lorenz Meier, Petri Tanskanen and Marc Pollefeys. An Open Source and Open Hardware Embedded Metric Optical Flow CMOS Camera for Indoor and Outdoor Applications, ICRA2013
The module has been developed by Samuel Zihlmann, Laurens Mackay, Dominik Honegger, Petri Transkanen and Lorenz Meier.
Frequently Asked Questions
- When will it be available? - It is available here and starts shipping next Monday, according to 3D Robotics
- Is the software available? - The software will be made available shortly open-source licensed. The module comes pre-flashed with the latest state.
- Is a ROS interface available? - Yes, here
- Will you offer a low-cost version? - The module has been designed to meet scientific standards and provide a baseline for what one can achieve with a reduced design. A low cost version is not planned, but we're interested to hear if someone is willing to contribute a cell-phone camera based design.
- Can I hook it up to robot XY? - Almost for sure, as it outputs the flow already in m/s and in MAVLink format
- Has it been used in scientific work yet? Yes, for example in this paper by Fraundorfer et al.
More information needed?