Northern Bites Blog

We finally got back our first robot from the Nao technicians. He had a broken arm and fried circuits. We are still waiting for three more robots to get fixed — two broken necks and a worn out hip.
This RoboCup has affirmed my belief that having lots of robots is crucial to having a successful team. With the Aibos, we had 12, now we only have 4.

In other news, our test scrimmage today was promising, (except that we were using all loaner robots which couldn’t kick). Tomorrow we’re looking forward to playing real games.

Marvin back from the shop

The Northern Bites will be playing in Pool B, Field A against Eagle Knights, from Mexico and Nao-Team HTWK, from Leipzig. Our first match is Wed. July 1st at Noon, against Eagle Knights. The second is at 3pm against HTWK on the same day. All times are Austrian times (+6 hours from East coast, and +9 from the West coast).

The full listing for placements for all the teams can be found here

Andrew, Elise, Jack and I have successfully arrived in Graz, and checked into our hotel with relatively few hiccups. The madness starts tomorrow at 8 am when we will try to register at the venue. Tonight, we will try to beat the jet lag, and see if we can’t stabilize the walk some more. Tucker will join us tomorrow, and Prof. Chown on Tuesday. We’ll try to post some pictures of the venue tomorrow.

Spring Summer Training has been rough on our robots. As we prepare to leave today for Austria, all of our robots are broken in some way, and only one is usable for soccer. Two have snapped necks, Marvin has his arm in a sling, and Trillian tore her hip-flexor. We should be getting them fixed in Austria, but the wait times might be long with so many other teams in a similar state as us. Hopefully next year will bring with it a new fleet of robot reinforcements (* hint-hint barry mills *). Checkout the current team picture below:

Training for RoboCup is hard work!

In never before seen footage, the Northern Bites have unearthed the legendary evolution of the Nao robot. Don’t forget to check us out next week, as we travel to Graz, Austria, to compete in RoboCup 2009.

Embarrassingly enough, the code we use to position the robots limbs hasn’t been updated since we’ve actually had robots (which is more than a year), and thus still has two of the hip joints out of order in the kinematic chain ‘model’. When we got the physical robots, we just switched the order of the joints as they were generated by the inverse kinematics system and were done with it. (The rotations of the two joints are centered at the same point, so it doesn’t matter for small angles like during walking) Partly as an exercise, and partly to fix this longstanding inconsistency I just spent some time slogging through the old Mathematica notebooks and corrected the bug. What I wasn’t expecting was to see a speedup of almost 3 times with the new joint order! A series of 10000 calls to inverse kinematics(IK) on several different targets, using both legs took .30 seconds using the old kinematic models, and only .12 seconds with the new models (on my dev. machine). Even with the slow older models, IK took only a very small fraction of our runtime, so this unfortunately won’t result in a huge boost to our frame rate on the robots, but nonetheless its still pretty neat. See after the break for my explanation.
Continue reading ‘Inverse Kinematics Optimizations By Fixing the Joint Order’