Let's Make Robots!

Hello! I was wondering if anybody could help me determine compatibility issues :(

Dear Robot enthusiasts,

Hello all!  This is my first question on here so please feel free to critique my writing style.  

Controlling a bots turning movements

Im thinking of implementing something like whats shown below. The bot scans from left to right, in increments of say 20 degrees, storing each value recorded. Then based on these readings, moves in the direction where there is no obstacle. Now here lies my problem. I cant figure out how to get near precise control of the bots turning movements. I can, say make it turn 90 degree left or right; but how do i make it turn to an arbitrary angle from a halted position? Is this possible, or am i being over enthusiastic?

Swap: Looking for GM10 motor and wheel

Im looking for somebody who wants to trade me a GM10 geared pagermotor for something that I have. I have a lot of stuff, so if you have the GM10 motor and wheel, and want to trade me it for something, let me know.

Controlling a DC Motor (Mabuchi FA-130)


I'm trying to run a Mabuchi FA-130 (#18100) DC Motor, it uses 3V and 2.1A when stalled. However, I did some measures and when I forced the motor to stall it consumed nearly 4A, but I think this was some sort of coincidence since It has never happened again.

I'm using a circuit similar to this one posted by Simon Z in his post:


(By Simon Z and taken from http://letsmakerobots.com/node/7990)

Reading USB mouse data in linux - somebody else C app and my python

Here is a slightly modified (added in hs and vs) c utility, and my python version. they will read the linux /dev/input/mouse data and convert it into status and x/y deltas

i noticed my python app seems quite different to the c app. not quite sure - default int()  types in c must be signed, i dont know... my second two bytes for x,y have MSB set if they are negative, but this value is also set in bits 5 and 6 of byte 1 from what my python tells me..


comments welcome!

What distance sensors are better and best?

I am working on a much faster & stronger version of Robot Wall Racers, using quite fast RC-cars

I want to use lasers as distance sensors, but I think they will be a little over budget, altough this is a paid for job :)

Yes, SRF05's clai, they can detect a broomstick on 3 meters.. but in reality they are not stable before say 1.5 meters.

1.5 meters when you are traveling at 25km/h is NOT a lot, when you even are set up with drifting tyres.

Programming help, sharp IR mounted on servo


I am trying to control my bot using a sharp IR sensor mounted on hitec servo with arduino mega. The pseudocode i have so far is as follows:

1. Set servo at 90deg and read IR sensor value
2. If val > 200, then stop the bot for a second
  a. Turn servo 0 deg completely and read ir val
  b. if val < 200 then turn bot left
  c. else turn servo 180 deg and read ir val
  d. if val < 200 then turn bot right
  e. else if cant turn right or left, reverse a bit and then turn the bot 180 degree and go straight.

360 Range Finder

I just received my SRF05 and I can't wait to start using it.  While I was thinking about it, it occurred to me that I always see the SRF05 mounted on a servo, which allows maybe a 180 degree field of view for a robot. I wondered if anyone ever mounted a range finding sensor on a motor so a robot could see in every direction. 

I think I may try to build a 360 degree range finder, but I wanted to open this as a topic and get some ideas. Here's what I'm planning. Let me know what you think.


activate alarm using microcontroller

I have 2 circuits:

1. flame detection

2. alarm circuit

Flame detection circuit connected to the pololu robot controller.(atmel AtMega 328p) I am able to get the values from the ir sensor of flame detection circuit. I need to active an alarm when the value is, lets say = 100. I'm a little confused how can I do that using microcontroller... it dosn't output 5v, so I guess I need to use something that will work as a switch when microcontroller drives HIGH or LOW it would turn on/off the alarm circuit.


Where to put an On/Off Switch on Picaxe 28x1


While I'm trying to solve my distance sensor problems , I've found that it would be convenient to have  an on/off toggle switch to be able to turn off the robot any time instead of having to wait until the program ends or replug the robot back into my computer to download a blank program to get it to stop moving. My question is: where on the board would I put this switch?

I am using the the starter pack with Picaxe 28x1 microcontroller and board.



Sharp GP2D120 IR Sensor Readings



I just built my first robot following the "First Robot" tutorial. The only problem I am having is with the Sharp GP2D120 IR sensor. When I run the code as per the tutorial (i.e. "readadc 1, b1" and "debug"), the values for b1 are displayed as:


123, $7B, %01111011, '{'


The readings do not change even if I put something in front of the sensor. Do those readings provide a clue as to what is wrong with my robot?


Thanks for any help you can provide.



Problem to control servo with picaxe

Hi everybody, 

This is the first time i use a picaxe 28x1 and i already have a problem...

Admin Edit:

Wherever you see Admin Edit: in a post it is because as I see posts that need cleaned up (title changed, useless posts removed, etc.) I am editting them and cleaning them up. We need to cut down on posts that have no relevance to the original post. This just makes too much to read for those who are catching up and doesn't help anyone. If you see a post that needs some cleaning send it to me as a private message and I will look at it.

Max712/713 Help!

I have been toying around with different power sources, and in my travels have made a few battery packs recently... The problem is, I havn't bought a charger. Awhile ago i got a few samples of Maxim IC MAX712/713 NiMih/NiCad battery charger ic's. I downloaded the datasheet for it here, but I have a few questions.


Clock movement as lightweight gearbox

Anyone ever try to modify one of those cheap battery operated analog clock mechanisms as gear train?  It would make an extremely lightweight gearbox for small bot.

Some quick research on the web provided some insight on how these things work:


Then I tore open a broken clockwork that's been sitting around for ages. OK, I tore it open first, then did the research. ; j

Thinking of ways to run 2 continuous servos.

2 questions that should tell me wether this is possible or not.


1.  Is it possible to connect 2 servos to the same potentiometer?  

2.  Is it possible to connect the signal lines of 2 servos to the same servo pin on a PICAXE?  Or would this overload the         poor little chip?


Pretty amazing robot video

 While I don't think they're as advanced as they look at first sight, they are still pretty darned impressive.  They must be using some tiny processors and servo controllers.




Hello, I look for an advice on the cards of programming for a future robot. I am going to build a "robot sumo" wrestling! But my problem it is because I do not arrive has to find a good card(map), I hesitate between some card(map) of programming as: PICAXE-28X1 or Cerebellum: http://botrics.com/products/cereb/ . I have the impression(printing) that it is the almost similar sound card but the picaxe in the air(sight) of credit note more memory(report)? Can you give him(it) advice(councils) to choose one maid card as my "robot sumo" wrestling?