Let's Make Robots!

Environment mapping

I'm currently working on an application for mapping the environment with a range sensor. Right now it's only a sharp sensor (GP2D12) mounted on a servo that is turning slowly, while the readings and corresponding servo angles are being sent constantly to my PC via serial. The program then converts the angle and distance to x/y coordinates and draws a map.

My 1st non-breadboard circuit :)

I know..a lot of you good folks could solder before you could walk and probably sleep with a soldering iron under your pillow (hope you remember to turn it off :), so here is this guy in his 30s bragging about his first circuit. Pathetic.

However soldering is a major challenge to me and actually the main reason I didn't get started with robotics years ago. It's just not easy for my unsteady hands. So I'm very happy to declare that I just finished my 1st working non-breadboard circuit. It's a motor+servo shield for my Arduino.

Serial oscilloscope

Hi guys,

I'm currently programming a software oscilloscope based on C++ and DirectX, thus the performance is very good. It works directly off the serial/COM ports. I was just wondering..is anyone else interested in such a thing?

I'm programming it for my Arduino BUT it should be able to work with Picaxe(or anything else) too. It's not gonna be a fancy pro application, but it works pretty damn well :) For now it's rather limited since it only accepts 8 bit values...well for now...

Shelf pins or thingies?

A rather odd question. I trying to make my own (servo) brackets by cutting pieces from CDs. That works pretty well. The problem is getting them attached in 90 degree angles. I believe what I'm looking for is called shelf pins. But I'm not sure. Here are some pics of what I'm looking for:


Robot position with quadrature encoder

I'm building a robot for environment mapping. It's a simple "start here"-class robot: 2 wheels, 2 dc motors and a range sensor mounted on a servo. I plan to hook it up with my PC 1st by USB and later on by wireless somehow.

I want it to drive around and send the range sensor readings to the PC which in turn will be building a map of the environment. The hard part will be knowing the robot's position relative to it's earlier position(s). I know this would be easy with a GPS or an accelerometer, however I wish to find a more lowtech/DIY solution, so here is my idea:

Control DC motors with an ULN2803

I live in argentina and getting thing shipped here is a mess, so I try to use whatever is available here (which is rather limited) whenever I can.

So I was wondering since I haven't found any of the typical H-bridges ...is it possible to control DC motors (speed + direction) with a ULN2803? These I can buy here. 

If so then how would that setup be? Do I need any additional components? If so then which (transistors, resistors, diodes etc)?

DC motors from DAGU

I'm putting together an order at DAGU. But I need to be sure about one thing. The DC motors (items 12 and 13 in the LMR price list), are they GEARED motors? I presumed they were, but then I mailed Claudia and I asked: "Item 13 (dc motor) in the list: Are these motors WITH gears?" and got this answer: "The DC motor will not come with gears". However I think she may have misunderstood my question cause they do look like geared motors....

Microservos from DAGU?

I was just wondering..does anyone have experiences with the 8g microservos from DAGU? I'm talking about item 19 in the PDF found on this page. How do they perform compared to other generic servos of similar size like HXT900 or TowerPro SG90?

Arduino vs. Picaxe syntax

The idea of this thread is to provide a place for asking question about the SYNTAX of the Arduino and Picaxe languages. I invite everybody to do the same and I'll be happy to help with Arduino syntax. Perhaps we can create a basic "dictionary" between the two and hopefully this will help the users of the respective platforms to SHARE code.

Perhaps we're not so different after all :)


Here is something to get us started:


Sensing servo feedback


I'm new to this forum, robotics, electronics and microcontrollers, however I have been programming a long time and I'm currently studying computer science.

I recently bought an Arduino board with the purpose of making robots for experimenting with my special interest: AI.

I wish to build a walking robot and experiment with varios ways of giving it a nervous system. So I will need to find a way to get feedback directly from the servos, thereby being able to read the amount of stress (load) they experience at a given time.