Thursday, August 28, 2014

"Well duh!" When sheepdog 'robots' fail

I always like having a bit of media coverage of what I do. Part of it is the purely narcissistic enjoyment of lots of other people simultaneously taking an interest in our work. But there is also a genuine insight to be had from reading what the wider world thinks about research.

Tracks of a simulated sheep dog (blue line) 'driving'
and 'collecting' sheep (black lines/ red dots)
Yesterday, Daniel Strömbom and Andrew King, together with myself and several other co-authors, published our paper on sheepdog and sheep interactions. The paper proposes a model for how a dog rounds up sheep. The basic idea behind the model is that in order to drive the sheep forward, the dog gets behind the flock and moves towards it. Then, if the herd becomes too wide it goes to a point which drives the furthest out sheep back towards the group. The result is a zigzagging motion as the
dog takes the sheep towards the pen.

The elegance, I think, of the result lies in the simplicity of the algorithm. Previous work had proposed more elaborate rounding up schemes, which were not as good at collecting large numbers of flocking individuals. And Daniel's algorithm also nicely matches the data which Andy had collected. The dogs use the same simple algorithm as we show works so well in computer simulations.

The media were also pretty interested in our results. Andy was on BBC radio, Daniel and Andy were quoted repeatedly in different newspapers and Jose Halloy stepped in did an interview for French radio. The reports were enthusiastic, talking about the possible development of autonomous robots inspired by our research. But looking at the comment sections of some of the newspaper articles, not all readers were completely convinced. One of the main points can be summarised by the following quote on the Guardian's website

"This is one of those "Well duh!" is discoveries, isn't it? I just don't know how farmers have managed for centuries without this research." 

Why the hell are scientists wasting time telling us something we have known for years?

The answer to this critique lies in the details. It is one thing to know that dogs go back and forward behind sheep, another to show that a simple 'collect' and 'drive' mechanism works properly. This is what is done in the paper, by showing when the algorithm works and when it doesn't. And it is when it fails that the insight are might be greatest. One thing not covered by the media is that when trying to round up very big groups of sheep our 'robot' sheepdog sometimes got confused. This is shown in the video below. The simulated dog gets caught between two groups and can't continue.
So we don't fully understand how sheepdogs solve large scale herding problems, and we still don't know how and to what extent real dogs can solve these problems. I can think of some plausible answers, such as dogs giving up and repositioning themselves after a time, but testing these requires more work and more experiments. In fact, there are lots of things neither scientists nor anyone else understands about flocking and herding in general, and there is certainly nothing obvious about the answers.

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