RoboGames 2008 Report

I’m really not sure where to start with my RoboGames coverage – the weekend was jammed packed full of interesting people and cool things – like talking with the machinist who worked on the NPC motors many of us use in our droids, to hanging out with the Orb Swarm folks or Grant Imahara from Mythbusters, or getting some inside info from the engineer who maintains the machines that spin our aluminum domes. Artoo even got in on some battle bot action in the arena and lived to tell the tail.

The event is held at Fort Mason in San Francisco each year and attracts thousands of people from all over the world. I was in attendance all 3 days with support from my friend Richard, and Gerard was there on Saturday with his R2.

The games themselves cover everything from the traditional battle bot arena tournaments, to robot soccer and sumo fighting. There are also special categories for art and bar tending robots. Maybe next year I’ll enter Artoo into the latter. In total there were 70 different competitive categories.

Artoo was a big crowd pleaser as usual, and many photos were taken with his admiring fans. My favorite was this one I found on Flickr by inkyhack.

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Posted by Chris on June 19th, 2008 in Events | 2 Comments

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Battery Power Issue Resolved

WonderCon was last weekend, and it was my first real test of Artoo since the rebuild. I’d mentioned that both Gerard and I had problems with our batteries. We’d figured it much be the carpet, but I hadn’t had the problem at Celebration 4 – and in the back of my mine I had a niggling theory what was causing it.

For Celebration 4 I’d used 3 7Ah 12V batteries, two dedicated to powering the NPC-2212 drive motors, and one for the body electronics like the sound system, dome drive and speed controllers. But during the rebuild before WonderCon I’d decided to consolidate all 3 batteries into one block to make charging easier. I’d had issues with power before, but thought the problem was resolved and I could consolidate my battery sub-system. Runtime at WonderCon was approx. 60 minutes vs 180+ minutes at C4 – which is a huge difference.

Unfortunately, while I was redesigning my electronics and adding the charging system, I’d forgotten that the RoboteQ speed controller really likes a solid 12V supply, so last weekend as my batteries ran down and when the NPC motors first start-up they were eventually pulling the supply well below the minimum 10.5V required by the controller. It’s “intelligent” and shuts down if it thinks it doesn’t have enough power to control the MOSFET drivers. It’s only for an instant, and starts back up almost immediately as power is cut to the motors – which resulted in the very slow and slightly jerky movement.

RoboteQ AX3500

So today to prove my theory, I reinstalled the the “dead” batteries from last week without recharging them, and added a separate 12V battery to the Power Control lines on the RoboteQ – Bingo! Worked first time. The issue was totally gone.

I’m kinda embarrassed that I went through this, because I should have remember that there’s a know “design feature” with low batteries and high current draw on this type of speed controller.

I’m now confident that I can pretty much run Artoo for multiple hours on a single charge – but I will have to reconfigure my electronics system again – making it harder to charge batteries in place.

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Posted by Chris on March 1st, 2008 in Electronics, RC | 2 Comments

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Cheap NPC-2212 Alternative Motors

On a tip off from a fellow builder I bought a few of these cheap motors for $45 vs $150 for the NPC-2212’s.

I already had my NPC-2212, but thought these would make for good spares, and apart from the extra holes and a longer drive shaft they’re a perfect match.

Cheap Motor vs NPC Motors

The NPC-2212 is on the right with the long leads and the cheap OEM motor on the left. Click on the image for more photos.

They can be found here.

Your mileage may vary!

Posted by Chris on April 23rd, 2007 in Electronics, Feet, RC | 6 Comments

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