I just want to share some of our experiences during the past few years with
all the rookie teams.
[Robot Acting Differently]
Please be aware that the NXT motors are running on battery pack! Just like
any computer, the NXT software and CPU on the brick should run consistently
every time. Since this is Robotics, beside the computer chip and software,
there are also moving parts (motors), sensors (that need adjustment), and
hundreds of LEGO pieces (that might come loose). We have a student
screaming this Monday "Did someone make any change to the Robot; it was
running perfectly when I left on Saturday!" What has happen was that he
wrote the program with a half charge battery on Saturday afternoon, and we
have fully recharged the battery before they met again on Monday! The fully
charged battery will allow the motor to run a bit stronger and will throw
off a (precision) program that worked perfectly the day before. Just like
any other battery operate power equipment, a fully charge power drill will
run differently versus one running on a low charge battery pack! Don't be
surprise when the kids have finish all their missions perfectly the Friday
night before just to find out nothing run right the next Saturday at the
competition! We blame it on the table, lighting and mission models at the
competition. But, it can also be that fully charge battery on competition
day!
It is really tough for a rookie team to deal with all the challenges, we
been there and know exactly what you are going thru. As coaches, parents,
teachers, we need to stay calm and not stress out as competition day is
quickly approaching since the kids are just watching us to see if we will
give up and throw in the towel or not!
[Block Skipping]
Please be aware that the 'Motor' block has a 'Wait for Completion' checkbox,
while the 'Move' block has a 'Next Action' selection of 'Brake' or 'Coast'
(on v2.0 only). These selections have significant affect on a program. As
an example, if you have the 'Motor' block to move an attachment (or a wheel)
for 1 rotation, but something is blocking it and the motor cannot turn a
full 1 rotation, with the 'Wait for Completion' check, the program will hung
since it is still waiting for the motor to complete the 1 rotation before
move on to the next block. However, if you don't check the 'Wait for
Completion' and the 'Power' setting for the 'Motor' block is not strong
enough to lift three loops, the program will just continue with the next
program block and continue running like the 'Motor' block never even get
executed.
[Debugging Program]
The best way to debug a program is to use a 'Wait' block (the hour glass
icon). Just change the default 'Touch Sensor' to the 'NXT Buttons' by
select it from the drop down list box. Now you can make as many copy of
this wait block as needed and place them anywhere after any block of code.
The robot will stop and wait until you press the 'Enter' button before it
continues on to the next block. You can delete these 'Wait' blocks after
you are done debugging and the program is ready to go as expected.
[Software Versions]
Please be aware that there are different version of LEGO Mindstorms NXT
Software (v1.0, v1.1, and v2.0), and there are many different version of
Firmware (v1.0, v1.05, v1.07, v1.21, v1.26, v1.28) out there. You will need
to make sure you have the right version of NXT Software matching up with the
right Firmware version. We have discovered it the hard way when our
students program on different PCs which have different Mindstorms NXT
Software and the brick (having different Firmware). In one case, we have
download Firmware v1.28 from a PC with NXT Software v2.0 to a brick, and
then download program written on an older NXT Software v1.1 to the same
brick. The robot starts acting very strange, and it did even lockup
sometime. The following are the best match up that we have found (any
additional comments on this are welcome):
Mindstorms NXT v2.0 - Firmware v1.28 (best).
Mindstorms NXT v1.1 - Firmware v1.05 (okay).
Mindstorms NXT v1.0 - Firmware v1.0 (very old).
To check the version of the NXT Software, run the NXT programming software,
click on HELP and select "About LEGO MINDSTORMS Edu NXT..". It should say
"LEGO MINDSTORMS NXT v2.0" or "v2.1" under the robot picture on the right
side.
There are two way to check the Firmware version. On the brick, when first
turn on, press on the right arrow about 4 or 5 times and select 'Settings'.
Press the right arrow 2 times and select 'NXT Version'. The first entry in
the display 'FW' will tell you the firmware version on the brick. The other
way is to connect the brick to the PC running Mindstorms NXT software, then
open any program and click on the 'NXT window' icon (it's the one on top of
the 'Download' icon). If the brick is connected, the Firmware version is
display at the bottom right on top of the 'Close' button. (This is also
where you can manage the memory on the brick and delete any unused programs
by clicking on the 'Memory' tab.)
(For Mac user check out this blog for installing NXT v1.1. and NXT v2.0:
http://foresthillslego.blogspot.com/2009/10/mindstorm-nxt-20-installation-on
-mac.html)
[Dead Battery]
If you insert a fully charge battery, but the brick will not turn on.
Remove the battery and check the spring where it's making contact to the
positive and negative posts of the battery. Sometime they are bent, and
will not make full contact. Just adjust it a little and this might fix the
problem. We also have a dead battery where it displays fully charge but
just not working at all. You can only test this by putting the
re-chargeable battery in another NXT brick. This is where 6 'AA' batteries
come into play, but be aware that the weight of the batteries can throw off
a programs on the robot that been programmed with the re-chargeable battery.
[Dead Brick]
We have encountered a few problems with dead brick. When download the
firmware, make sure the PC and the NXT brick's batteries are fully charge.
If the firmware download failed during update for some reason, the brick is
dead and will not turn on. To fix this the brick will need to be reset (by
pushing the hardware reset button with a paper clip) and download the
firmware again. If your NXT is clicking when you insert batteries, push the
hardware reset button for five seconds before you insert the USB cable. This
will ensure that the brick initializes correctly for the firmware download.
[The hardware reset button is located within the LEGO TECHNIC hole below the
USB connector on the NXT brick.]
Best wishes,
T. (Curt) Tran
2007, Coach Team #3563, Rabid Llama Lords.
2008, Coach Team #324, Scitobor.
-----Original Message-----
From: First Lego League in Virginia and DC
[mailto:[log in to unmask]] On Behalf Of Phil Smith III
Sent: Tuesday, November 03, 2009 3:16 PM
To: [log in to unmask]
Subject: Re: [VADCFLL-L] more problems
I'm sorry you're so frustrated. I can certainly believe it, especially this
close to Regionals!
At the risk of being called a Pollyanna (or worse), let me suggest that you
make this into a learning exercise for the team:
- What could (not *should*) they have done to avoid/plan for this? ("Have a
spare brick" being the obvious, if not necessarily practical, answer)
- What can they do *now* to get around it? (Do any of them own a brick? Can
you buy one and then return it once this one is fixed? Have you called LEGO
for support?)
- Could it be a battery issue? Have you recharged it since the problem?
- Can you try it on a PC instead of a Mac?
FLL is all about solving problems. This is beyond the level of problem they
SHOULD have to deal with, of course, but that doesn't mean they can't be
encouraged to step up and try to figure it out.
And I hope you'll come to competition anyway -- the table runs are 1/4 of
the points, and the whole point is the experience, not "winning". In fact,
they might find another team with an idea, or a spare brick to lend...
--
Phil Smith III
Virginia State Judge Advisor, 2007, 2008, 2009
Judge Advisor, Northern Virginia Regional tournaments, 2007, 2008, 2009
Division 1 Judge Advisor, Virginia State tournament, 2006
Coach, The Capital Girls, Oak Hill (retired)
Team 1900 (2002)
Team 2497 (2003)
Team 2355 (2004)
Team 1945 (2005)
-----Original Message-----
From: First Lego League in Virginia and DC
[mailto:[log in to unmask]] On Behalf Of Sherene Silverberg
Sent: Tuesday, November 03, 2009 2:38 PM
To: [log in to unmask]
Subject: [VADCFLL-L] more problems
Lee Hilt kindly sent me a picture that showed us how to find the reset
button. My son depressed the button (I was unable to see it with my
old eyes) and now the brick refuses to switch on or to stop clicking
so we can't reload the drivers.
I have to say that I went into this FLL League with great excitement.
I am now totally turned off by the entire experience. Buggy
equipment, buggy programs, drivers download pages hidden so well that
unless you are given the exact page, even Google's spiders struggle to
find it.
I have received 6 emails in the half an hour since I sent my original
email. All these people are experiencing the self same problems as we
are experiencing with the programs that run, not resembling the
programs that were downloaded.
This is the most appalling situation I have ever experienced. Lego
needs to get their act together and sell equipment that works. Driver
and firmware updates should be easily found. This is an exceedingly
expensive exercise and for this money, I expect far better service and
equipment.
My team has spent more work trying to fix Lego issues than they have
on developing their programs. It is most frustrating for my team to
write a program, have it run perfectly 3 times and then on the 4th
time have to execute a program that does not resemble the one that ran
perfectly 3 times prior.
Now we have a dead brick just because we attempted to reset it.
Just in case you haven't realized it yet, I am fuming.
Sherene
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