NXT-G 2.0 : Datalogging
I was very lucky to attend one of the recent LEGO engineering conferences in Brisbane, organised by LEGO Education and presented by Melissa Pickering from Tufts University (home of RoboLab)
One of the highlights was a quick demonstration of NXT-G 2.0, which will include a specific datalogging section. No screenshots are available as the graphical interface is still under development, but they are looking at a January 2009 release date.
It looks great and has two levels to it that I could make out. The first level requires no blocks whatsoever, rather it opens a dialog box asking what sensors you have connected to each port and for how long you wish to sample. This suits a handheld logging experiment as you cannot move motors or perform other actions while logging. The second level introduces a 'datalogging' block which does the same thing, and include it with all your regular blocks in your program so you could drive a robot around, collect some data, move to another spot and collect some more data etc.
If you are connected to your computer when taking data (bluetooth or USB)
NXT-G 2.0 will show a realtime graph of the data being collected. One of the nifty features they showed was the 'predict' mode, whereby teachers could pose a question about what shape a data set would look like, students could then 'predict' what the data would look like by using a pencil tool to draw it out, and then run the experiment over the predicted data to see how closely they matched. All data will be exportable in text file format for analysis with other programs (excel etc)
The other big change that was presented was 'exportable' myblocks. This means that if you are using myblocks, you just save your file as normal, email it to whoever you want, and the program will run without needing to send the individual myblocks as well.
NXT-G 2.0 is being released by LEGO Education, not LEGO Retail, so it may be a little more difficult to find. They will be including 4 projects with the software, the most impressive being a probe dipper that can raise/lower a probe into a beaker and also rotate between beakers.
Overall it looks great and I can't wait to get my hands on it.
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Damien Kee
www.domabotics.com
One of the highlights was a quick demonstration of NXT-G 2.0, which will include a specific datalogging section. No screenshots are available as the graphical interface is still under development, but they are looking at a January 2009 release date.
It looks great and has two levels to it that I could make out. The first level requires no blocks whatsoever, rather it opens a dialog box asking what sensors you have connected to each port and for how long you wish to sample. This suits a handheld logging experiment as you cannot move motors or perform other actions while logging. The second level introduces a 'datalogging' block which does the same thing, and include it with all your regular blocks in your program so you could drive a robot around, collect some data, move to another spot and collect some more data etc.
If you are connected to your computer when taking data (bluetooth or USB)
NXT-G 2.0 will show a realtime graph of the data being collected. One of the nifty features they showed was the 'predict' mode, whereby teachers could pose a question about what shape a data set would look like, students could then 'predict' what the data would look like by using a pencil tool to draw it out, and then run the experiment over the predicted data to see how closely they matched. All data will be exportable in text file format for analysis with other programs (excel etc)
The other big change that was presented was 'exportable' myblocks. This means that if you are using myblocks, you just save your file as normal, email it to whoever you want, and the program will run without needing to send the individual myblocks as well.
NXT-G 2.0 is being released by LEGO Education, not LEGO Retail, so it may be a little more difficult to find. They will be including 4 projects with the software, the most impressive being a probe dipper that can raise/lower a probe into a beaker and also rotate between beakers.
Overall it looks great and I can't wait to get my hands on it.
--
Damien Kee
www.domabotics.com
Comments
But is there any other "major upgrades" than the datalogging function? Ofcourse their maybe fixing some bugs and other small things like they did from NXT-G 1.0to 1.1. But to be honest, if there won't be any other major upgrades in it I most likely won't buy it. But I'm sure alot of schools would appreciate the function though :)
-Andy
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Brian Davis
LEGOmom
Brian and I have both done some fun datalogging without the upgrade, do a search on datalogging in the posts.
It certainly does now bring it up to par with RoboLab. Now all they need is pre-emptive multitasking :)
damo
Cheers
Chris
I don't recall there being any other improvements, but I could pull out my notes and check.
Josh
What is the RoboLab sampling rate?
Why is 10Hz a problem?
Please do check your notes.
-Andy with his crazy ideas :P
As to why high sampling rates are desired, think about measuring the accelerations on something as it hits the ground during a fall. If you only record the acceleration every 1 second (a 1 Hz rate), the imapct accelerations may very well occur during a time when the program is not "watching" or recording the sensor - so it's not a very good representation of the event. On the other hand, high sampling rates often are much "noisier" than low samples (properly done), and require more post-processing & interpretation.
Andy, as far as a "graphing block", sure, that's doable - even adding the ability to scroll the graph back and forth and rescale it should be possible under v1.1. But I'm not sure I see the need, when I generally have a perfectly good computer sitting a short distance away. Right tools for the right job sort of thing.
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Brian "still long winded" Davis
Brian said just about everything - for things like acceleration you need much better than 10Hz. Toren and I agree, NXT-G is still no match for RoboLab in terms of processing power and datalogging speed.
Josh
When I was speaking to Flemming, he wouldn't give me a definite on sampling rate. He said it would definitely by at least 10Hz but *most likely* be around 100Hz. He wouldn't commit to a number as he said the firmware guys were still working on it.
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damo
PASCO now uses datalogging that samples at 250,000 Hz (which is much more than I can image you would never need). They do point out that "When sampling at rates less than 100 samples per second, circuit noise can be visible on a data graph. The 750 Interface, however, provides 8X oversampling to reduce noise and provide smoother data curves.". If Flemming is right in what he said to Damien (ie. they are considering 100Hz), then I hope the firmware guys are logging our discussion!
Yes, Robolab is faster - but that doesn't always give you what you need. And if you want raw speed, skip it and jump to something like RobotC. There are different solutions out there for different folks & different applications.
Yes, PASCO has loggers that sample much higher than the NXT... so does Vernier, National Instrument, and lots of other datalogging companies. Just repeat to yourself something a wise man once told me about the NXT... it's a toy. Remember that. An amazing, powerful, flexible, educational, and imaginative toy... put it's a *toy*. If you need datalogging at 1000 Hz, this is not the platform. But if you want rough, low-frequency datalogging with some amazingly simple, yet useful sensors... then this is a very, VERY useful toy. Under NXT-G, Robolab, NXC, Java, pbLua or RobotC (the last two, to my knowledge, much faster than the previous offerings, if what you really need is speed).
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Brian Davis
I understand what you mean about implementing datalogging at a lower level. Point is you could already do that, so the new datalogging implementation isn't as important, especially with the reduced speed.
Can NXT-G log at 100Hz without using LabView Toolkit? (because almost anything in labview toolkit can be done directly in robolab, with labview)
We should test how fast RoboLab and NXT-G (and possibly other languages) can sample compared to how fast the sensor actually updates.
Josh
Were you at the LEGO Engineering Symposium in January? If anyone recalls, I asked the question about frequency of datalogging directly.
Josh
My point was that while the 10 Hz rate might seem slow, that's not a limitation of NXT-G - only of the "wrapper" imposed by a nice front end for kids by a custom datalogging environment. If you want faster, it's there. And a great place to take kids to "NeXT".
> Can NXT-G log at 100 Hz without the Toolkit?
Well, I just tested it. The program took me 20 seconds to write, and about that long to download. It can log the light sensor, timestamped, every 10 ms. That's 100 Hz. The program is just four blocks in a Loop, and a 10-year-old can easily program it (in fact, my 11-year-old just did this, for a science fair project, on his own). It's not hard. In fact, slowing it down "correctly" (so you don't have the problem of undersampling data) is a more signigficant problem... perhaps exactly why the NXT-G v2.0 Educational release has a custom system, so kids don't *have* to deal with that.
As far as wanting truly fast datalogging, both pbLua and RobotC end up smashing everything else I've seen... but they are still, in the end, limited by the sensor update rates and FLASH writing rates (although the second you can get around by not using FLASH, or using it in very efficient and specific ways).
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Brian Davis
Sorry I couldn't make it to the Symposium (long flight from Oz) but I did ask the same question at the Australian conference last week. perhaps they have improved the code since then and are more confident with the higher sample rate.
Brian is right with the whole 'wrapper' issue, essentially they are prettying up the GUI so that you don't have to think about the individual blocks. I think benefits a lot of teachers as so many I talk to struggle with learning a new piece of technology.
Yes I know it is easy for those of us experienced to put together blocks, but I think LEGO Ed is aiming towards those teachers who don't have the support and are not sure where to look for it.
Teachers todays are already loaded down with way too many things to teach, combined with their ever increasing administrative workload, that they find it difficult to find the time to 'play' with these new concepts.
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damo