Thanks again to everyone who helped make today’s booth at the Robotics Expo a huge success again this year. Â Booth volunteers included Ben, Don, Mike, Michael, Brandon, Nick and Jared, with material support from Patrick, Sarah, Eric, Dave and Katlynn. Â [Apologies in advance if I missed anyone].
The subject is a potassium sodium tartrate (Rochelle salt) crystal mounted in a brass holder, with a copper contact wire for detecting the crystal's piezoelectric properties. From the perspective of the camera, this setup looks like this:
OMG’s innaugeral FirLumber Rally was a great success, with 17 cars competing. Â Official results will be posted shortly, but in summary, Dave’s electric cheater was the fastest, Eric’s elephant was the most creative, and Nate’s car was the least effort to build. Â Additionally, Dan’s kids’ cars were the fastest among the Squares.
Thanks to all who took part in our Trebuchet Contest! We had perfect weather and all involved had a great time. With nine people competing on six teams, we saw a wide variety of designs and lots of experimentation.
Each team fired three shots, which were analyzed for efficiency and for accuracy. The efficiency score is calculated as the length of the best shot divided by the mass of the counterweight – to discourage anyone from using small cars as counterweight and hurling the projectiles all the way to Dodge Street. The accuracy score is the standard deviation of the three shots. To combine these into a final score, each category was normalized to 5 points for the best team in that area, with proportionally fewer points going to every other team. As a result, the best possible score is ten points, which would only be awarded to a team winning both categories.
|Rank||Team||Efficiency (ft/lb)||Accuracy (St Dev)||Score|
|4th||Kyle and his Dad||7.9||18.3||4.0|
|6th||Don, Stephanie, and Sarah||6.2||31.2||3.2|
Ben, competing with a trebuchet constructed years before and “conveniently” fitting the contest requirements, had the longest throw of the day at 214 feet, but the use of a rather large counterweight dropped his efficiency to mid-pack, though not nearly low enough to offset his astonishing repeatability and accuracy.
Dave, winner of the “Least Effort Possible” award which nobody has bothered to create, gave a spectacular performance, particularly considering that his machine was constructed and tested in under fifteen minutes.
Eric nearly forfeited the contest after some mysterious last-minute bugs, but came back with a very solid 94-foot throw. Unfortunately, with two of his three shots launching backwards, his accuracy score reminded everyone to stand well to one side of a firing trebuchet.
Kyle and his Dad arrived with the only machine too large to be assembled indoors. Installing a competitive amount of counterweight earned them a respectable score, but before and after the contest, their 50-lb maximum capacity gave the neighbors something to think about.
Kevin competed with the only machine requiring three hands to safely load, and was also the only entrant to attempt self-amputation during testing. Despite this, the device proved acceptably reliable and fired many shots without incident.
Don, Stephanie, and Sarah may have earned the lowest score, but they were also the only team to compete with no prior testing. Their trebuchet was not completed until several minutes after the start of check-in and was immediately put to the test with none of the tinkering and tweaking afforded by the other teams.
Once again, a huge thanks to everyone who took part in this contest! We know it was the most difficult challenge we’ve yet conceived, and everyone who took part worked extremely hard to make the firing line yesterday. We promise the next event will carry wider appeal – more on that in the coming weeks.