I also wonder too- we all know the robots are often not 100% consistent- but the children do have a chance to show their programming- and "programming" will show during the robot design judging.....I have told my team that cause they did some very nice programming- battery power equally makes things erratic. Laura On Nov 4, 2010, at 3:29 PM, Mandy Wilson wrote: > Turns out that our problem was a faulty motor on the left side which > caused the merry go round effect when it turned right. My son, who > is homeschooled, read all of the emails and helpful suggestions that > came in and ran upstairs to test. Sure enough when the right turn > was changed to a left, the program worked perfectly. (It didn’t > occur to me that was the only right turn the team had done in the > last few days). When he replaced the motor the right turn in that > program worked perfectly. Always nice to have a motor burn out 2 > days before the competition! Now apparently many things are just > slightly off as this motor is a little different than the last and > my son is not pleased that he and his friends now have to redo > almost everything! Maybe this is why people drop out of events? No > the team is not dropping out, but it will be nice if they can get > back to where they were. Thanks to everyone who helped. I don’t > know what this team would have done without all your help as today > the merry go round effect was occurring 50% of the time. I’m sure > the motor would have been completely dead in 2 days. > > Mandy > > From: First Lego League in Virginia and DC [mailto:[log in to unmask] > ] On Behalf Of Eric Palmer > Sent: Thursday, November 04, 2010 1:43 PM > To: [log in to unmask] > Subject: Re: [VADCFLL-L] NXT merry go round effect > > My team this year had a robot with a particular mission and > attachment set that had a "veer left bias" They changed the whole > robot to our backup and it "veered very slightly right" on further > inspection the first robot has an axle going through a beam that has > been damaged so there was more friction on the left side. > > For the right bias they moved a counter weight to the left and the > robot goes straight most of the time. But even with that it varies, > sometimes badly. > > We are using disposable batteries this year and they monitor voltage > closely. The front missions they use fully or nearly fully changed > batteries and the last mission they use batteries whose top voltage > has been lowered. > > They use a slight moist cloth to wipe the dust off the table before > practice and we occasionally wipe the dust off the wheels and let > the tires dry. They store the robot upside down so the wheels don't > get flat spots. > > The team pays attention to many more factors for repeatability as > well. > > But that said we still have problems with erratic behavior. Turing > for example seems to work best (for repeatability) one wheel at a > time. That slows down the missions but makes the missions more > repeatable. > > All learning opportunities. > > Eric > > On Thu, Nov 4, 2010 at 1:24 PM, Nagesh Chintada <[log in to unmask] > > wrote: > This is hard to figure out without seeing it, but couple of > questions come to mind: > 1. Has your team tried to reduce the power, to say, 50 or below? > 2. How is the robot balance and center of gravity? For example, does > it happen if the attachments are removed? > 3. I noticed that sometimes loose wheels can cause strangest > behaviors in movement, so not a bad idea to check if the any part of > the attachments/ frame and wheels are not loose. > > Just a comment: The great fun of FLL is ruined especially to rookie > teams because of all the variability in the NXT Robots. These are no > doubt complex products, and it is not easy to get consistent > behavior. It requires some experience and lots of practice. This is > not my first year, but I am still learning. > > I wish Lego or FLL would make it easier for all the teams - and > improve the fun factor - by providing some basic information/ > instructions/ best practices to reduce variability as part of the > NXT kit or FLL kit. Just a thought. I'd like to see more teams > having more fun than struggle so much. > > Nagesh > > > > On Thu, Nov 4, 2010 at 10:15 AM, Mandy Wilson <[log in to unmask]> > wrote: > This turn does not involve sensors. It’s just a plain point turn. > > From: First Lego League in Virginia and DC [mailto:[log in to unmask] > ] On Behalf Of Eric Palmer > Sent: Thursday, November 04, 2010 10:09 AM > To: [log in to unmask] > Subject: Re: [VADCFLL-L] NXT merry go round effect > > I wish I knew what causes this. We see it occasionally. Something > lose wires. Sometimes changes in battery levels. Do check to make > sure that if you are using sensors that they are working reliably. > > > On Thu, Nov 4, 2010 at 10:06 AM, Mandy Wilson <[log in to unmask]> > wrote: > > > 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. > > > -- > Nagesh Chintada > Phone: 703-829-0284 > > > 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. -- 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. 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