Dr. Mark Read

Research Fellow, Charles Perkins Centre, The University of Sydney
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My Research Gate

CoCoRo “excellent”, year 2 GA

Another trip to Pisa, this time for the anual CoCoRo general assembly (GA). For those not familiar with EU projects, this is where the project showcases its progress to a panel of reviewers (two in our case) who evaluate our progress and cast a critical eye to keep things on track. SSSA in Pontedera were hosting us, and the first thing we noticed was the impressive water tank set up:

There was an operational Jeff, controllable over remote, but at least not requiring any power cables. Jeff, the more advanced of the two platforms being developed in CoCoRo, is extremely impressive. Everyone is instantly drawn to the blue-light systems of our AUVs, and they are eye catching. But to watch it move was something else. Its very fast, and very maneuverable. Whereas Lily, being cylindrical, spins easily, Jeff was fast to swim in a straight line and rotation was only achieved when it was desired. A video of Jeff can be found here. Some photos demonstrating…

The reviewers were very impressed with all of this, including the live demos (which worked! Always risky having live demos). They rated the project “Excellent”, which was nice… if you have to leave home for a project meeting you can at least be told you’re excellent :o). James’s work on the operating system and all our work on the simulation received special appraisal with the reviewers noting that these were thankless and unglamorous, but essential, jobs.

And of course no trip to Pisa is complete without a visit to this:

Chain & Shoal

The CoCoRo project is driven by a ‘big vision’, a search and rescue scenario where a swarm of autonomous underwater vehicles (AUVs) is deployed at the surface of a body of water. Their task is to find something, the black box of a downed plane for instance. As the swarm shoals to the bottom it must leave behind a ‘relay chain’ of AUVs to maintain communication with the surface. The swarm explores the sea bed, and the chain must follow it, always maintaining the communication line. As the swarm shoals further from the origin, where a team of anxious humans awaits the discovery of the black box, the chain must get longer. Hence, AUVs must dynamically re-assign themselves between chain and shoal functions. This can’t go on forever, eventually there won’t be any shoaling AUVs left. At this point the shoal should be informed that it must turn around, and not stretch the chain to breaking point. In this manner, the chain grows (and can also shrink) and moves with the shoal as it tries to locate the black box.

This is a hard problem, directed communication underwater is short range (at least on our robots), they can’t see each other very well, they are trying to navigate a 3D environment, and they have a tendency to float off and lose contact with the group. We’ve been working on shoaling in recent months, and have some solutions – at least in simulation – to this problem. Chain formation, navigation and dynamic reallocation of AUVs is harder still. But we are getting close. Below is a video showing proof of principle that it is possible, again, in simulation at least (it’s 3.7Mb, give it a second to load…)

There are some other assumptions made in the video: we have assumed for now that AUVs can locate one another’s relative position very well. In reality they will have to use bluelight LEDs and sensors, and can only determine the distance to another AUV within a 120 degree cone. But if you can’t make it work using “underwater GPS” then its certainly not going to work using bluelight. Getting this onto real platforms will be challenging, and cracking it will be quite an achievement. Check back here in 6 months!

Oh, in case anyone is interested, here’s a promotional video for CoCoRo with AUVs choreographed to do what we are now creating actual algorithms to accomplish autonomously (its pretty, but remember it’s not real).

New year, new student

A new year is upon us. We are now 14 months from the end of CoCoRo, not quite time to panic, but not impossibly far off either. Its time to knuckle down to some AIS (artificial immune system)-oriented fault tolerance in our shoals of AUVs.

Over the past year I’ve done some work on shoaling in underwater swarm robotics. Communication and distance sensing underwater is problematic, electromagnetic signals are hugely attenuated. Our robots don’t have the capacity for sophisticated visual processing, so we rely on bluelight systems (blue LEDs and photodiodes) to detect distances between AUVs. The range of bluelight and radio frequency systems underwater will be 50cm at best. This equates to about 5 AUV body lengths. Our studies to date have shown that creating well-aligned shoals without communication of velocities between members of the shoal is incredibly difficult (if not impossible). This work is going to be carried on by Sophie Alexander, an Engineering MEng student who is going to investigate shoaling algorithms in this challenging underwater context. To the left is a nice picture of 15 CoCoRo AUVs, well aligned (but not shoaling) on the table.

CoCoRo General Assembly

Yesterday the CoCoRo project held its first general assembly meeting, marking 6 months since the start of the project. The meeting was a success, with all partners presenting interesting aspects of work conducted in the early stages of the project.

James Hilder and myself, representing the Uni of York, presented initial ideas concerning the operating system design, and early work on porting algorithms into the CoCoRo simulation. AUVs flocking based on Reynold’s Boids algorithm is particularly interesting to watch (at least I think so!)… here’s a video. The algorithm represents one of several possible solutions that allow swarms of AUVs to explore their environment as a group without losing contact with one another.