This autumn we are continuing work on the UAV toolkit with Karen Anderson and her research group at the Environment and Sustainability Institute. This time we have a mission to help the Westcountry Rivers Trust by coming up with fast and cheap ways they can build maps of farms to determine water run-off problems, which gives farmers proof they need to get funding to fix pollution issues.
In order to make the software usable in this case, we decided on two directions. On the one hand there needs to be a simple way to start and stop programs (or “flight modes”) that read sensor data, as well as defining certain global settings, ie. flight altitude, desired image coverage etc. At the same time, the code to define what this does needs to still be programmable in the app – and more complex behaviours need to be possible to support both kites and UAVs. Our philosophy is that it has to be open ended, as we don’t know where the toolkit it might be useful (ie. crisis mapping situations) or what new sensors will be available on a device in the future.
One specific set of new behaviours we need is for kite mapping. We already have the ability to choose when to take pictures based on GPS and altitude, but with a kite there can be lots of turbulence and the camera is in a much less controlled state, flipping around taking shots of the sky etc. So we need to calculate things like jerk from change in acceleration and use orientation sensors to only take photos when the lens is pointing directly down, within some degree of acceptable margin.
Below is a section of the code that calculates if we are pointing down using the magnetometer and accelerometer – the drag drop visual code can now be used to build normal Scheme functions using a touchscreen (a bit like scheme bricks). In fact I managed to do all of this work on the phone. There are now two types of code, the main programs or “flight modes” that you can run from the front screen, and a library of editable functions which they use. This means there are now three levels that the software can be used – using it without needing to see any of the code at all, editing the basic behaviour like which sensor’s data are captured, and finally modifying the more detailed code to make it do completely new things.