Posts Tagged ‘serial’

Friday Night Robotics – iRobot Gearing?

Posted by Erin, the RobotGrrl on Friday, August 28th, 2009

This is actually from last Friday, August 28th!

I recently ‘inherited’ an iRobot Create. It’s a Roomba, but without a vacuum, and made specifically for hobby robotics.


Friday Night Robotics - Aug. 28

Getting it to work with an Arduino was excruciatingly hard at first. It does come with a controller on board, but the instructions for that were more sparse than just using plain serial commands. Or, maybe I misread them and they are the same things…

In any case, I used the DIN connector to connect to the Arduino so that it can send and receive commands, as well as be powered by the iRobot!


Friday Night Robotics - Aug. 28


Friday Night Robotics - Aug. 28


Friday Night Robotics - Aug. 28

Sending commands to the iRobot is interesting… you start off with a number from -500 to 500 in mm/s, then…
1. Take the absolute value
2. Convert this to a hexadecimal number
3. Split the hex into two
4. Add a sign bit infront of the first part
5. Convert the two parts into bytes

This works very well for 500 mm/s and -500 mm/s.

However, when trying it with -100mm/s and 100mm/s, the -100mm/s goes faster than the 100mm/s!

I believe this is the code where we got the -100mm/s to be almost the same, even though it made no mathematical sense…

  1. Serial.print(145, BYTE);
  2.   delay(50);
  3.   Serial.print(1, BYTE);
  4.   delay(50);
  5.   Serial.print(244, BYTE);
  6.   delay(50);
  7.   Serial.print(1, BYTE);
  8.   delay(50);
  9.   Serial.print(244, BYTE);
  10.   delay(50);
  11.  
  12.   delay(5000);
  13.  
  14.   Serial.print(145, BYTE);
  15.   delay(50);
  16.   Serial.print(241, BYTE);
  17.   delay(50);
  18.   Serial.print(244, BYTE);
  19.   delay(50);
  20.   Serial.print(241, BYTE);
  21.   delay(50);
  22.   Serial.print(244, BYTE);
  23.   delay(50);
  24.  
  25.   delay(5000);

The only thing we can think of is that the gearing of the wheels is different for driving backwards.

We’re going to keep playing with it, next time we’ll be seeing if we can get some sensor data from the bump and IR sensors!

Post to Twitter Post to Delicious Post to Digg Post to Facebook Post to Reddit Post to StumbleUpon

Posted in: Programming, Projects, Robot.

RBBBs and Pololu SSCs

Posted by Erin, the RobotGrrl on Tuesday, August 5th, 2008

I received the two RBBB’s, 1 FTDI TTL USB cable, and two Pololu Serial Servo Controllers (SSC) I bought a few weeks ago. :) Since then… I’ve been tinkering with them quite a bunch. I learned an incredible amount too from just a tiny board!

Building up the RBBB wasn’t too hard. At first, I printed off the wrong ‘instructions’ – which mind boggled me a bit until I noticed that they were indeed wrong. Once I had the right instructions printed… it was more simple. I was worried about the polarity of the bigger capacitors. :) After I had it all finished… I went and looked up the FTDI-USB cable specs. This cable is pretty interesting if you think about it, 1 wire turns into 6 more colourful wires :) -Gnd, CTS (clear to send), +5V, TX, RX, RTS (request to send). I downloaded the Blink program without any problems… until I wanted to test it. The LED wasn’t blinking! After about 5 minutes of intense thought, I realized that there was no LED on pin 13. That was a stupid mistake!

Another stupid mistake, but this one is funnier, was when I was trying to test the other RBBB.
… I forgot to put the chip into the IC socket. =D That really made me ‘lol’ for 10 minutes.

Then, I was trying to fit it into the breadboard… lets just say it took a longer than normal time.

When the Pololu SSCs showed up, I was pretty excited! Then when I saw them… they are REALLY tiny! It was a big challenge to solder these without them flying out of my hand. I don’t have a 3rd hand tool to hold it steady, so I would sometimes have to hold the ‘pinchy-things’ with my elbow and hold the solder and soldering iron with my hands. :) The headers were extremely difficult too…

Getting the Pololu to work with the Arduino is pretty aggrivating. I think I’m almost there, I just have to switch the input to the logic level side as I was using the RS-232 one. I thought that the Arduino used RS-232 on its TX line, but it doesn’t. It uses a non-inverted logic level (er well, that’s at least what I read). Tomorrow I plan on looking up the difference between the two :D

Here are some pictures… I finally threw the desoldering pump out the window (joking) and bought solder wick. Also finally bought NON-LEAD SOLDER! =D

RBBB nice and shiny Everything on the kitchen table for RBBB RBBB and instructions RBBB Finished! RBBB FTDI Cable (black is Gnd) RBBB Soldering iron is all gooey and yuck! FTDI confusion RBBB not working!! RBBBs RBBB on Breadboard Pololu Board in Bag with Seal thing… Fits! What is that weird blue thing? It’s really tiny… Pololu Board is challenging o_o Meanwhile, turtle is escaping… (LOL) Ooo Hard to solder… Omg- so small even for my fingers Soldered it to the pinchy-thing (LOL) 2 Headers are difficult! You can see where the servos will go! THIS IS SO DIFFICULT AND FRUSTRATING! (and worthy of caps lock too) O-O :) Pololu! Yaay! Complete by the looks! NO LEAD!

Other than playing with these, I’ve been flow-charting A LOT of AI programs, and learning more first-order predicate logic. I really like logic and the probabilities and Bayes and everything!!!!! Also having fun thinking about random and bell curves… More back-dated Stanford blog posts to come (so many photos hahah)!

Post to Twitter Post to Delicious Post to Digg Post to Facebook Post to Reddit Post to StumbleUpon

Posted in: Programming, Projects, Robot.

Store


    The story of my store begins with my Styrobots, which begins with my acceptance into the Stanford EPGY Summer Institutes Artificial Intelligence program for 2008. In order to go there, I needed money! So, I came up with Styrobots.
    All of the money from the store goes towards my Robotic Fund. This enables me to buy parts for the robots that I enjoy creating!
    I appreciate all help! :D


    Google thinks that you may want to check out these pages:

Robotic Fund

Housekeeping