SPAM problem
Sunday, September 30th, 2007NXTasy has been under a large-scale SPAM attack lately, which is why some posts got many unproper comments. I’ve removed commenting till further notice, at least until I can set up a better spam filter.
Guy Ziv
NXTasy.org Editor
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Autonomous robotic bulldozer
Tuesday, September 25th, 2007
Here’s a YouTube of a totally autonomous robotic bulldozer. It uses the new Power Function (PF) motors, which are totally controlled by the NXT via infrared signals through the new HiTechnic ‘Infrared Link’ (or IR-Link) sensor about to hit the markets. This “sensor” would allow you to control up to 4 IR recievers (so up to 8 motors!) without any output port of the NXT. You can see the bulldozer scanning the environment with the Ultrasonic sensors and then flattening anything in its path using the Ripper and the blade. Thanks Tim for sharing this with us!
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One Week Left for NXTasy Challenge #3
Monday, September 24th, 2007Did all you ANxT breeders gave this challenge a try? One week left for the 3rd NXTasy challenge! The record weight/ANxT body ratio is around 30, held by 222Doc who insists he’s ‘for fun only’ so the 1st prize (60$ cupon for online purchase at mindsensors.com, thanks mindsensors!) will go to the next highest score (unless someone else pass 222Doc, anyone trying?) which currently is a ratio of 24 reached by Lren.
Keep up! only seven days left….
Guy Ziv
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NXT Rube Goldberg machine
Monday, September 24th, 2007
An artile in Geekdad blog talks about “Leonardo’s Basement” , an educational organization for boys and girls ages 6 to 16 and their families in Minneapolis. One of their creations is this Rube Goldberg machine made of 6 (if I counted well) NXT’s which was built by some 10 & 11-year olds made in their “Sensors and Motors and Gears, Oh My!” class.
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NXT in SecondLife
Saturday, September 22nd, 2007
see discussion topic here.
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Vernier and NXT
Friday, September 21st, 2007With the coming release of their NXT adaptor, Vernier put online an impressive webpage http://www.vernier.com/nxt/ with links, NXT-G block and information on sensors the new adaptor works with. These includes:
25-g Accelerometer
Barometer
Charge Sensor
Colorimeter
Conductivity Probe
Current Probe
Differential Voltage Probe
Dissolved Oxygen Sensor
Dual-Range Force Sensor
Electrode Amplifier
Extra Long Temperature Probe
Flow Rate Sensor
Force Plate
Gas Pressure Sensor
Hand Dynamometer
Instrumentation Amplifier
Light Sensor
Low-g Accelerometer
Magnetic Field Sensor
O2 Gas Sensor
ORP Sensor
pH Sensor
Relative Humidity Sensor
Salinity Sensor
Soil Moisture Sensor
Sound Level Meter
Stainless Steel Temperature Probe
Surface Temperature Sensor
Thermocouple
Turbidity Sensor
UVA Sensor
UVB Sensor
An impressive list, isn’t it?
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Parsing GPS NMEA message
Tuesday, September 18th, 2007
After few hours of LabView coding, I finally made an NXT code (see larger image here) that can parse NMEA (GPS) $GPGGA message (i.e. GPS fix data). I thank Dick Swan for his RobotC code which inspired the algorithm. Timing tests show that the NXT using firmware 1.05 runs this code in around 92 milisecond. This would be good enough for update rates of few Hz.
Next I plan to design the NXT-G block for BT GPS. I was thinking of a block with two ‘action’ options - ‘update’ and ‘read’. The former delays the program till it reads a BT buffer (or a timeout occurs), and tries to parse the new NMEA message. It returns a Yes/No output which say if it was successful (so one can make a ‘Wait for’ block until a successful GPS data is read). Once a good data is read it is stored in a ‘global’ data holder. The later option ‘read’ returns the last stored value of lat. and long. position (maybe only seconds part?), #satellites and altitude. In this mode you can define a waypoint (as GPS coordinates) and a distance cutoff (in meters) and the block returns a Yes/No value if it is closer then cutoff. It will also return the heading and distance to waypoint (so with a compass sensor you can steer your NXT to the waypoint). The basic use principle would be having one ‘update’ GPS Block in a loop on one sequence wire, and your running program with ‘read’ GPS Blocks on a second sequence wire.
Comments/suggestion? Please use this forums topic.
Posted in nxtasy, personal, projects, news | 2 Comments »
An Updated Firmware
Tuesday, September 18th, 2007Lego has released an updated firmware. Here is what the web site says:
“Updating to LEGO MINDSTORMS NXT Firmware V1.05 will improve the following:
- Multiple datafile control within user programs
- Communication with 3rd party external devices
- Bluetooth communication within user programs
NOTE: Only update your firmware if you have experienced issues related to the above”
Does anybody know more details about these improvements?
Via thenextstep.
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ANxTs at work!
Sunday, September 16th, 2007222Doc reached a weight/ANxT body weight ratio of 30! Where will it end? Remind you - challenge #3 deadline was postponded to October 1st. Even if you can’t beat 222Doc - give it a try! You’ll learn a lot from this challenge. I will put online all contributions at the end of the competition - and winner will get 60$ cupon courtasy of mindsensors.com!
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Processing and NXT
Sunday, September 16th, 2007I’ve got the following email from Diego Baca:
For those who want to use the NXT with Processing (http://processing.org ). Jorge Cardoso has created a great Processing library to interface with the NXT brick. ( http://jorgecardoso.org/processing/NXTComm/).
I have created a simple applet using his library and also have posted instructions of how to get it working using OSX. http://www.diegobaca.co.uk/NXT/nxt.html
Hope this is of interest for everyone!
cheers,
diego
What is Processing? From the website:
Processing is an open source programming language and environment for people who want to program images, animation, and interactions. It is used by students, artists, designers, researchers, and hobbyists for learning, prototyping, and production. It is created to teach fundamentals of computer programming within a visual context and to serve as a software sketchbook and professional production tool. Processing is developed by artists and designers as an alternative to proprietary software tools in the same domain.
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NXT-G and GPS - closer than ever?
Saturday, September 15th, 2007
I’ve been working on the issue of BT GPS connection for the past few days, ever since Antonio’s NXC code demonstrated that this is a possibility. In the LabView diagram above (click here for full resolution image) I show a preliminary step toward this goal. I’ve made VIs (i.e. the LabView term for blocks) that read an ASCII stream, and some prelimiary string parsing VIs. Since I have no BT GPS, I had my PC connect as the slave device, and wrote another LabView code that sends the NMEA-0183 formated string:
$GPGGA,023346.028,3604.1654,N,08655.7973,W,0,00,50.0,198.2,M,-31.6,M,0.0,0000*76\r\n
at specified intervals (e.g. each 1000 milisecond).
The resulting file stored on the NXT contains a long list of this message:
GPGGA,023346.028,3604.1654,N,08655.7973,W,0,00,50.0,198.2,M,-31.6,M,0.0,0000
GPGGA,023346.028,3604.1654,N,08655.7973,W,0,00,50.0,198.2,M,-31.6,M,0.0,0000
GPGGA,023346.028,3604.1654,N,08655.7973,W,0,00,50.0,198.2,M,-31.6,M,0.0,0000
GPGGA,023346.028,3604.1654,N,08655.7973,W,0,00,50.0,198.2,M,-31.6,M,0.0,0000
.
.
.
without any errors so far. From another test is seems that as I suspected the NXT ‘catch’ the GPS data correctly every 2-3 cycles of my “GPS” data stream.
What’s next? Parsing the GPGGA data, and making the NXT-G block around all this… Keep watching for it!
In the meantime, Antonio posted me an improved version of the code. He claims this code loses only 20% of the messages (compared to ~60% in mine, and his old code). You can download the new code here. I still need to figure out what makes the difference, and see how I can implement it in LabView…
Questions/comments - use this forum topic.
Guy Ziv
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Standard firmware and GPS data
Friday, September 14th, 2007As I posted yesterday, Antonio Scarfone made a NXC code that managed to read a Bluetooth GPS textual (NMEA-0183 format) readout. I’ve tried the same thing long ago, but for the reasons listed below dropped this project thinking it is impossible…
Why did I think so? Well, the Bluetooth SDK describes in the end of Appendix 1 (Communication protocol) the structure of the “expected” ‘data packet’ - 2 byte packet size, command type byte, command byte and data. This is very different with NMEA format which starts with e.g. $GPGGA and ends with *XX\LF\CR (XX is a 2 char hex checksum, \LF\CR are line feed and cartridge return chars). For me, and many other AFOLs this inconsistent format seemed impossible to overcome with the standard LEGO firmware. Other firmware like pbLua (and soon RobotC) have BT ’stream-mode’ where program can deal with the BT port like simple serial port. GPS communication with pbLua was reported a while ago, and Steve Hassenplug recently converted his Green Monster to use GPS with RobotC. But using GPS with NXC or NXT-G? I thought it will never happen.
All this was true till Antonio’s code came about. I’ve spent several hours looking at the code and going over the firmware source files trying to understand how this works. Here’re my preliminary conclusions. (more…)
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