Let's Make Robots!

BTbot

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Update #2 10th June, 2011
Added another video showing the robot doing tight pirouettes on a small kitechen scale.

Update 10th June, 2011
Added new pictures, which represents how the robot is looking today. Also added links on the bottom to all key components I've used. I switched out the small breadboard for a cleaner look and soldered the components directly. I also added a PIR motion sensor (what to do with it?) and a ultrasonic distance measurement module.

<strong>Hi everyone
This is the first robot I submit to LMR. I wanted to get into robotics so I started looking for a platform. I came across the LMR Mr. Basic on dealextreme.com, so I bought it. I now kind of regret that, as I think the chassis is overly complex, and a better solution would just be some laser cut sheets with two geared motors instead of the whole 4wd setup.

But anyways, the robot is not yet finished, I'm not sure if I will keep the bluetooth controls or the chassis. This is just for showing off what I've got working so far. The motor controller is based on the St Micro L298, which is perfect because of its 2A specifications, and my motors stall at ~1.8A. The bluetooth module was bought on goodluckbuy.com (~$10), one of my favorite sites for bulk electronic components and other cheap modules. Both the motor controller and the bluetooth module are described in detail on the external links. Of course, you can choose where you'd want to post questions.

It doesn't have any sensors or other inputs yet. I have outputs for the current sense resistors on the L298 breakout board (which is etched mirrored, that's why the copper is on the top side, big pain to solder), but the current uC AtTiny2313 doesn't have ADC inputs. I have PIR motion sensors, temp, sensors, ultrasonic modules, GPS module, compass modules laying right next to me, but no idea how to implement them in any "fun" way yet :( I'm happy for some input on this. Well, I guess there's not much more to say here. I'm gonna change the 3xAA battery pack for a 7.4V lithium i think. Theres a big voltage drop on the L298 so it will effectively be closer to a maximum of 6 volts to the motors. Just hope the nylon gears on Mr Basic handles it!

Key components and modules used on this robot (with links to exactly where I bought them):
LMR Mr. Basic 4WD robot chassis
PIR Motion Sensor
Bluetooth SPP Module
Ultrasonic Range Finder
L298 Motor Driver Chip

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Nice project and writeup on the blog :) The bluetooth module is the cheapest through hole version I've seen!  I want to assume it must be configured via UART (some such as RN-42 are configureable via Bluetooth) but can't complain at the price point.

I just got an original Motorola Droid and I've started doing some Python programming using SL4A, which is a great way to create simple text based bluetooth applications.  This page got me started.

I'm glad to see you use AVR, you might find my input/output macro header file useful for general C programming with AVRs.

Cheers

Yes, I configured it via UART on a computer terminal emulator.

The SL4A environment is awsome! There are so many people out there developing in python. I prefer Java, because of it's similarity to C. The link was very informative, thanks!

AVR is by far my favorite uC of choice. I've been doing it for a while now, so I'm to comfortable with bit operands and the like to start doing changes in my programming style. But it looks like an easier way for beginners to learn devoloping on AVR, and that is awsome too!

A funny function is to use the PIR motion sensor as it should be used ;-)

Just let the BTbot sit and wait until something is moving...maybe grilfriend/wife/cat/dog/turtle (oh no, a turtle moves to slow and might trick the sensor :-D) comes in and then let Mr. BTbot wake up and run forward a little...or use it in the opposite way. Once motion is detected it will freeze (wonder if this is even possible since the motion of the moving car is already present...how to know if the car or something in the surrounding is moving?)

I like the freeze part! But yeah, the cae movinh may be an issue :P

I saw you asking about the Mr Basic kit on the shout box, but I think you were offline by the time I noticed.

There was a Mr. Basic challenge on this site quite a while back, so a bunch of us bought the kits and made robots. Search for 'mr basic' and you'll probably find them.

I will check it out. I'm considering making it a 2WD, as I understand was it's original design? Right now it takes so much power to just do simple turns.

Great robot! Seems like Android cells are easier than iPhone for remote. Keep up the good work :)

Thank you, Korel! It seems that iPhones do not support the SPP bluetooth protocol, which is really just as easy as standard serial communication.