Programming: The Competition Events

The code team is charged, among other things, with the task of plotting a course through the four sailing events of the International Robotic Sailboat Competition. Here are the four events:

Event 1: Fleet Race

In the first event of the competition, the fleet race, all of the teams complete the Match Race Course together. I can’t wait to see it.

Since there are so many boats in the water, manual rudder control is allowed, even expected.

Points: 10 for the boat with the fastest finishing time, 9 for 2nd place, etc. Times are adjusted by the square root of hull length.

Challenges:  Even though we’re allowed to take manual control, we’ll want to use the boat’s smarts to trim the sails and maybe take control of the rudder too. The human operator will have to be well-practiced and know the Racing Rules of Sailing so we don’t get ourselves disqualified. We may want to set up our interface such that the boat gives the operator advice along the way, and the AI can take over when there aren’t other boats around.

Event 2: Station Keeping

In Station Keeping, each boat sails into a 40×40 meter box (shown at right). The boat must stay in the box for 5 minutes, and then leave the box as soon as possible after the 5 minutes has elapsed. Manual control is allowed, but cuts your points by 50%. Our job is to make sure that doesn’t happen.

Points: 0.1 point for every 3.3 seconds your boat stays in the box, up to a maximum of 9 points (5 minutes). The boat that leaves the box soonest after the 5 minutes have elapsed gets an additional point.

Challenges:  We’ll have to maintain control while we’re within the box (don’t drift into irons!) and have a plan for exiting at exactly the right moment. That may mean skirting the edges of the box as the five-minute timeout approaches, or approaching one of the box edges with a carefully modulated speed so that we arrive just in time.

For this, it’ll be important to get a boat on the water and start tuning our algorithms as soon as possible!

Event 3: Navigation Test

The navigation test is is another tough one. A 60m upwind leg followed by rounding a buoy in a predetermined direction, and then returning to pass between a closely-spaced set of buoys.

Points: 2 initial points for rounding the buoy in the correct direction, if we don’t finish the event. At the finish  line, we get 10 points for passing between the two red buoys (bulls-eye; 3m apart), 7 points for passing between the blue ones (9m of space), and 5 for crossing the finish line outside the buoys.

Challenges:  

1. First, our upwind course will have to be planned such that we can round the buoy in the appropriate direction. Algorithms for this are on the way.
2. Finally, we’ll actually have to aim the boat appropriately so that it makes it between the buoys while running. Shouldn’t be too bad; the existing algorithm on our test bench can accomplish this very well.
3. Our test bench can accomplish #2 up there since it has an accurate position sensor. On the competition boat, our GPS position estimate will have to be accurate enough to guide us between the buoys. Since the GPS is our only sensor for this, we’ll have to make sure that the buoys are very well mapped-in and hope that they don’t drift significantly. In future years, we’d love to have a vision system that actually spots the marks.

Event 4: Presentation

This is an onshore event where we wow the judges with our beautiful boat, shiny interfaces and highly effective algorithms ;). They also like to see the level student involvement on the team. In our case, the team is made up of students only.

Points: maximum of 10.

Event 4 isn’t really a sailing event, so let’s move on to…

Event 5: Long Distance Race

10km in the English Bay. Obstructions and shallow water nearby. Need I say more?

Points: 1 for completing each of 8 “legs” of the course. The first boat to finish autonomously in each category gets 2 bonus points, and the second boat gets 1 bonus point. 50% point reduction for using manual override, except for avoiding moving objects.

Challenges: Surviving for long enough to complete the course, and plotting a course that will allow us to finish under the time limit of 6 hours. We’ll also need to use location awareness and obstacle avoidance algorithms to avoid the coast and stationary objects. And this is on top of the basic sailing stuff: setting course, trimming sails, tacking, etc. that we’ve been working on.

We surely have an adventure ahead!