Starting first with the caveat that we are using snap-together plastic parts which "NASA or factories" would never use, my experience is that improvements in precision come with better engineering. Each decision that the kids make in their robot design matters. Using the "knob wheel" as a drive gear would be a bad idea for precision, while most of the "normal" gears work quite well. What kind of tires are they using? Are they rigid or bendable? Are they using crawler tracks? What kind of gear ratios are they using? Are they using programming techniques that depend on consistent battery voltage? Is their chassis rigid or highly flexible? Is the weight of the robot over the drive wheels or offset? Is the weight unevenly distributed? All the rules of physics apply and everything affects the outcome. One of the best parts of my coaching experience is when the kids discover something about why they are getting inconsistent results. Like when they discover that using too much power causes the wheels to slip on the slick mat slightly (and unpredictably) at the start. Or that the strategic object they attached to the robot actually caused the robot chassis to raise a little, taking weight off the wheels and making them more prone to slip in turns. Or that the spinning back wheel of the classic "tribot" design can alter the the direction of the robot as it swings around when you start to back up. At the tournaments you will see teams that operate with great precision and ones that don't, all using the same NXT brick and motors. If your kids are frustrated this year, have them look at the tournament for teams with consistent results across their 3 runs. Then have them ask the robot designers of that team "How did you get your robot to be so consistent? What did you learn about inconsistency? Did you use any special parts that helped (e.g. different wheels)?" The answers will mean so much more to the kids coming from other kids rather than from a book or coach, and they might get more excited about competing next year with their new-found knowledge. I always tell my kids that their goal is to have each mission work 9 out of 10 times. Their tendency is to try an idea once and if it doesn't work to fiddle with it. How do they know if that wasn't the 1-in-10 failure and that the next 9 times it would have worked great, unless they tried it multiple times? So even learning good engineering "process" is something that produces consistency in the outcome. I hope your team can turn your frustration into a quest for more knowledge and understanding. After all, that's what makes a great engineer! Stuart From: Brandy bergenstock Sent: Thursday, November 04, 2010 11:59 AM To: [log in to unmask] Subject: Re: [VADCFLL-L] NXT merry go round effect Is it just me, or does anyone else believe their is something inherently wrong with the gears for the new NXT brick, (or maybe it's the new brick itself)? Robotics is suppose to be very precise. Yes, some things go wrong- sometimes. But I'll be darned if my team's best consistency isn't 1/3 of the time. NASA or factories would never settle for such horrible ratios. My team is disheartened by the lack of precision in the machinery they are working with. I can only hope that fll come out with a 2.0 gear for their NXT brick by next tournament. I'm sad they came out with the new, inconstant model than than sticking with the very consistent RCX models and gears. Personally, my team is putting their hopes in the skit and teamwork skills. Regards, Brandy -------------------------------------------------------------------------------- From: Mandy Wilson <[log in to unmask]> To: [log in to unmask] Sent: Thu, November 4, 2010 10:06:53 AM Subject: [VADCFLL-L] NXT merry go round effect Our team has a part of its program where the robot is supposed to turn some nominal amount (around 30 degrees) and for some reason every 5th run or so, it spins about 120 degrees. They have put a reset motor block, a break block and even a 1 sec wait block in front of the errant turn in order to stop the issue, but nothing they have done works. They’ve even tried deleting the block and putting another one in. They thought it was the gearing on the wheels coming loose which also causes it to act up, but on the 6-9th run it works fine and then at run 10 it does it again. Well not quite that predictable, but you get my point. Has anyone else had this problem and is there a way to fix it, or should the team just be resigned to blow a round at the tournament? Thanks for all the help – this is our first year! Mandy -------------------------------------------------------------------------------- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list". VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe. -------------------------------------------------------------------------------- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list". VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe. -- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list". -- VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe.