Craig's Robot Blog

Lia, Robot Genius

2008-11-22T20:19:00.000-08:00

Lia finished the Lego NXT humanoid, and programmed it to say "Good Morning" and shake its head when its arm button is pressed, but only if the lights are on. (If the lights are off, Mr. Roboto is sleeping.) Brilliant!

Lego NXT Bluetooth

2008-11-04T09:20:00.001-08:00

Weirdly, when I went to plug the batteries in the NXT brain, the LCD was working. Guess about 48 hours juice free was enough to purge the demons. Trying to figure out how to get Bluetooth working on Lia's iMac with her NXT, I called tech support again, and they sent me this:

1. Turn off the NXT brick.
2. Unplug the Bluetooth Dongle.
3. Launch the NXT software.
4. Click the Go button next to Start a New Program
5. In the lower right corner, click the button that looks like a NXT brick to bring up the Communications window.
6. Click on the Communications tab
7. Remove everything in this list by clicking on the item and the Remove button.
8. Turn on the NXT brick.
9. In the brick menu, choose Bluetooth and then My Contacts
10. Delete all the Contacts listed
11. Plug in the Bluetooth Dongle.
12. Make sure the NXT brick is still turned on.
13. Back in the NXT software, return to the Communications Windows.
14. Click the Scan button (you may to do this a few times until the NXT brick appears in the Communications list). Note: When you click Scan, the MAC default Bluetooth dialog pops up and scan for devices. Select the NXT and click Select.
15. Once the brick appears in the Communications list, click the Connect button.
16. Type in 1234 if prompted for a Passkey and click the OK button.
17. The NXT brick should make an alert sound. If 1234 is selected, press the orange button to confirm the connection.
18. Back in the NXT software, the Communications window should now show a status of Connected. The Bluetooth icon on the NXT brick should now show a <> (in the upper left corner of the brick) which means that you are paired.

Lego NXT humanoid

2008-11-04T08:49:00.000-08:00

For her next robot project, Lia wants to build a humanoid NXT. The LCD stopped working on the main NXT brain, so I called Lego tech support, and they sent me a long list of instructions. I could either (1) walk into Lia's room, log her out, log into my Gmail to read the instructions, or (2) post them here so that I can access them without logging Lia out. I choose (2):

1. Unplug the NXT Brick from the computer.
2. Turn the NXT brick ON.
3. Flip the brick upside down, so that the USB port is at the top left of the brick.
4. In top left-hand corner of back of brick, is a hole with a reset button. Use a paperclip (straightened out) to push this button 5 seconds or until the screen goes blank. You will often hear a soft ticking emitting from the brick.
5. Set the brick down for now. Do not connect to the brick to the computer. Please be aware the brick will not turn on at this point, but will work once the process is complete.
6. Next, please visit http://mindstorms.lego.com/support/updates/ . Locate MINDSTORMS NXT Driver v1.02 and click either on the link under PC or MAC depending on your operating system.
7. Save the file to your desktop (upload1F7B2420-A5ED-44FF-

9460-E262657029DC.zip for PC or upload41336AE8-40FE-4AF9-8050-3F1D9A28427B.dmg for Mac)
8. Unzip or Decompress the file using your favorite unzip utility (Macs will automatically do this when double-clicked)
9. Open the folder upload1F7B2420-A5ED-44FF-9460-E262657029DC on the PC or upload41336AE8-40FE-4AF9-8050-3F1D9A28427B.dmg on the Mac.
10. Double-click the Setup.exe file on PC or the LegoDriver.mpkg on a Mac to install.
11. Follow the prompts.
12. Click Shutdown.
13. Plug in the NXT while the computer is off.
14. Start the computer.
15. Visit http://mindstorms.lego.com/support/updates/. Locate LEGO MINDSTORMS NXT Firmware v1.05 and click either on the link under PC or MAC depending on your operating system.
16. Unzip or Decompress the file using your favorite unzip utility. (Macs will automatically do this when double-clicked)
17. Launch the NXT software.
18. Click Tools and Update NXT Firmware.
19. Click the Browse button and choose the MINDSTORMS NXT Firmware folder on the desktop. Click the OK button.
20. Click the Download button. (If the brick is not detected at this point, check that the cables are connected firmly. If that does not resolve the issue, insert new batteries in the brick.)
21. Once the download process is complete, the NXT will turn.
22. Turn the NXT off and then turn it back on. The NXT Brick is ready for use!

Linuxed!

2008-10-05T09:49:00.000-07:00

There's nothing like taking a job as Department Chair to slow down robot construction. Having had the first weekend in two years without a major undertaking or disaster under way, I naturally turned back to building Robot 3.

Simon promised me that if I gave him a hunk of metal and an AutoCAD file, he'd lathe Robot 3's body. How can you pass that up? So I started learning AutoCAD, which is anything but intuitive. I'm up to the section on layers in Just Enough AutoCAD 2007, a book I highly recommend for those new to AutoCAD (it's my third try at a good AutoCAD book, and this one's the best.)

As something of a diversion, the program I'm using to program Robot 3's brain is Dynamic C version 9, which up until the present is the only reason Mothership is a multiboot system. (Dynamic C only runs on Windows.) Having recently upgraded Mothership's Linux to Fedora 9 and VMware Workstation to 6.5, I decided once again to try to program Robot 3's brain from the Linux side. Dynamic C talks to Robot 3's brain through Mothership's serial port, and I spent the entire morning trying without luck to configure VMware to talk to Fedora's serial port.

Then I had the simultaneously brilliant and boneheaded idea just to use a USB-to-serial converter to have Dynamic C running in VMware talk through Fedora to Robot 3's brain. Eureka! I can now program Robot 3 from the Linux side, and no longer need to boot up Windows just to program Robot 3. Here's a picture of Robot 3's brain being programmed through the USB-to-serial converter from Mothership.

I now return to learning AutoCAD!

Boarded!

2007-02-11T15:17:00.000-08:00

After breadboarding, I finished my schematic in gEDA's 'gschem', and then turned it into a printed circuit board using gEDA's 'pcb'. I then sent the Gerber files that 'pcb' generated to Sunstone, and a few days later a pretty PCB appeared in the mail!

(Note the "Niederbot 3.0" in the bottom right corner, hee hee.) I had ordered all the parts from Digikey, Mouser and Jameco, so by the time the board arrived, it was time to solder. Everything works, and Robot 3's brain is complete!

Rat's nest!

2007-02-04T14:56:00.001-08:00

"Where it's at! I got two turntables and a microphone..."
(Beck, Odelay)

Like Robot number 2, Robot number 3 needs two motors for motion. Adding a second stepper was harder than I thought. The stepper motors skipped, ending up in different positions and completely defeating the purpose of using stepper motors in the first place. So I learned a lot about steppers, voltage requirements, how choppers work, and as in life, how timing is everything. Finally I added a cool digital servo, which was easy to get going as the signal could be driven straight from the Rabbit, and my breadboard was finished. What a rat's nest!

Going Mobile!

2007-01-21T20:08:00.000-08:00

"I can pull up by the curb, I can make it on the road, Goin' mobile..." (The Who, Who's Next)

What would a mobile robot be without mobility? One of the main features of Robot 3 is tighter control over motion using stepper motors. I hadn't previously used stepper motors, and so had planned to use a ready-made motor controller, and put off making an in-board hardware designed controller as a possible project for Robot 4. I chose the Active Robots Easy-Step 3000 controller, and the Sanyo Denki H546 bipolar stepper motor. I hooked up power, connected the leads, and watched smoke billow from the $80 controller.

There's a lot in this world 80 bucks more fun than watching smoke curl from a PC board. Four rather compelling hands of poker, for example. A decent steak dinner, replete with martini, a decent Cab by the glass, Caesar salad and chocolate desert. Twenty five comic books. Oh, well.

So I set about breadboarding a bipolar stepper motor controller using the STMicroelectronics L297 and L298 chips. In about the time it took the Bears to win the NFC championship and about half the time it took the Colts to win the AFC, I had a spinning Denki.

gEDA Rules!

2007-01-12T06:31:00.000-08:00

It may appear that my roboting was recently quiescent, but not true! I've been a very busy beaver robot-wise. Mainly I've been catching up to my breadboard by creating the schematic and plans for the printed circuit board using gEDA. gEDA is an open-source full featured computer assisted electronics design application. It's free, but it really needs Linux to run: I tried the cygwin port, and it's still a little buggy. I've been painstakingly making schematic elements for the Rabbit, XBEE, and other specialized devices, and their respective PCB elements. It's time consuming and not very photogenic. But I'm caught up now, and can return to breadboarding. Here's a snippet of the schematic...

And here's a snippet of the PCB design. Pretty cool!

Zigbee gone wild!

2006-12-09T19:36:00.000-08:00

This was a watershed weekend in Zigbee land. Thanks to Tony Garcia at Rabbit semiconductor (many many thanks, Tony!) I learned that setting up the Zigbees as wireless serial radios was, well, trivial. Zigbees are amazing little buggers indeed. One breakthrough was simply to add a serial port to the mothership, which I did via a USB serial device. I could then set up the Zigbees to talk to one another, viewing the communication in terminals on the mothership, and then everything fell into place. Experiment two was to set up a simple echo, where the mothership sent a character wirelessly to the rabbit, and the rabbit echoed it back. Experiment three was to have an ultrasound distance measurement sent from the Parallax Ping))) Ultrasonic Sensor wirelessly to the mothership, and displayed in a terminal window. Here's a picture of the setup for these experiments:Note that the "child1" Zigbee connected to the rabbit is wired directly without jumper cables--the Zigbees truly are remarkable self contained units. "Child2" is connected to the mothership. Here's the very simple schematic for a 3-wire serial connection from the rabbit to the Zigbee:Pretty simple, eh? Distances from the sonar module appear in a terminal on the mothership's screen! Amazing!

Mothership's cool new CPU fan

2006-12-03T13:47:00.000-08:00

Here's the computer that programs and ultimately will talk to the robot. It's an Armor Thermaltake box with an ASUS P5LD2 motherboard that I put together last winter, housing a 3 GHz Intel Pentium D dual core CPU with 2 Gbytes RAM and 7 hard disks. I'm running Fedora core 5 linux and Windows XP.

Here's a picture of the motherboard with the original CPU fan that came with the Intel Pentium D CPU chip. Over time, this fan got louder and louder and LOUDER until Karen's mother could hear it over the phone all the way in Hawaii. I must admit I didn't believe she could hear it over the phone until it happened twice. Karen's mother thought it was a printer running. It even made listening to the television in the room difficult. I discovered it was the CPU fan by sticking my ear in the case, and listening for the loudest spot, then verifying it by jamming a letter opener into the fan for half a second. Blissful quiet. A really bad idea, but I was major frustrated by that point.

So I went on Newegg and started reading user reviews of CPU fans, and found that the Zalman CNPS9500 LED had a lot. I ordered it--it's mondo cool looking.

Putting it into the motherboard was a 4 hour job with lots of blood, sweat and tears. I had to pull out the mobo to attach a bracket to the back. Ugh. I used Arctic Silver 5 thermal compound between the fan and the CPU, another highly rated item on Newegg.

But eventually I got the CPU mounted. Ahhh, cool and quiet. I could even hear my hard drives now, including the Linux backup one that just failed. Arrrrgh, it never ends!

Karen pointed out that this probably would have been something less than a 4 hour job if I hadn't spent the time to photodocument it, including 2 different camera tripods and 2 lenses. She has a point.

Wireless Proof of Principle

2006-11-24T16:37:00.000-08:00

The ZigBees turn out to be cool little buggers--wireless modems that you can program. Here's one getting her firmware updated. The ribbon cable is connected directly to the computer's serial port.

First, I put the Rabbit 3720 into its development board, connected it to a ZigBee, and set up a child Zigbee. I ran the peer-to-peer sample program, and voila! My desktop computer was happily reporting the status of the child Zigbee.

Next, it was time to lose the development board. It takes up space on my desktop, and won't be part of the final robot. As the Zigbees have two serial headers, one with .1 inch spacing that serves up RS-232 level signals, and one with 2 mm spacing that has TTL/CMOS level signals that can connect directly to the Rabbit 3720 core module, I just had to figure out which slots on the 2 mm header to connect to the 3720 module's pins. Here are my notes so I won't forget when time comes to design the PC board.

Here are the two ZigBees, one connected to the Rabbit 3720 core module, running the sample program, and the other sitting next to it, connected only by electromagnetic radiation. The desktop computer is happily reporting the status of the child. Claire pulls out the red power lead, and the child disappears from the desktop. She plugs it back in, and the child reappears. Proof of principle!

Now, it's time to do a lot of unphotogenic programming. I need to flip around the ZigBees--right now, the mother ZigBee is connected to the Rabbit 3720 module and desktop computer, and is just reporting the status of the child. I need for the 3720 to be out on its lonesome, communicating with the desktop. And there's brisket to be eaten, so enough for now!

The eyes are working. Or ears. Whatever.

2006-11-20T16:46:00.000-08:00

Every so often a man needs to build a robot. This is the story of robot number three.

Like all robots, number three will have sensors, effectors, and a brain. But like My Favorite Martian, number three is to communicate wirelessly with my desktop computer. I've chosen for the brain the Rabbit 3720 with ZigBee 802.15 wireless modules. Like my previous robots, the primary sensor is ultrasonic. I've chosen the Parallax Ping))) Ultrasonic Sensor for the eyes. Or ears. Or bat thingies. Whatever. For the first step, I've connected the ultrasonic sensor to the brain, and it's working:

Here's the schematic connecting the Ping Ultrasonic Sensor to the brain with a tri-state buffer:

And if you're curious, I'm using a regular ATX computer power supply for the breadboard. They're great, they're powerful, and they're cheap. Problem is, you plug it into the wall, flick the switch, and it just sits there doing nothing. So you have to trick it into believing it's actually connected to a computer. Just find the green wire in the 24 pin Molex connector, and wire it to one of the black pins. Use a paper clip. It's cool.

Well, that's all for tonight. I'm sleepy. Time to power down.