Let's Make Robots!
Short description This is cr3cX, a robot I am building for my son to play with, and with the hope to teach him some programming. Current version is cr3c4. Read more
Standalone system based on Raspberry Pi. Now with a laser cut frame and video streaming working. Status as of 2012.09.14 I could not make the old webcam (Microsoft … Read more
These are instructions for the optiboot bootloader shipped with Arduino 1.0
Optiboot works with ATmega168 but, to return the correct chip signature, for ATmega168P some changes must be done. The easy solution is to copy attached file to the … Read more
Cheap and easy USB interface for programming and communicating with microcontrollers
My work with ATmega microcontrollers was based mostly on ATmega168 and ATmega328 with Arduino bootloader on custom boards. For programming and communication through … Read more

cr4cX Motor Controller

This blog is about the cr4's motor controller - updated 2012.03.22

Controller features:

  • controls two H bridges;
  • reads, interrupt based, two quadrature encoders;
  • implements PID algorithm for controlling the speed of the motors;
  • synchronize the motors;
  • communicates through Serial and I2C/TWI;
  • monitors the supply voltage;
  • monitors the current through the motors.

AI Challenge anybody ?

I have found aichallenge.org like two weeks ago and I could not stop myself to play there.

At first I was thinking at swarm robotics but software only. In their challenge you will lose if you choose this way but you can use the tools they offer to build your swarm robotics farm, especially if you know python to customize the framework. The robots can be writted in different programming languages - I use C++.

cr4cx - Security robot/Telepresence

cr4cx should be an autonomous home security bot.
It must also work as a telepresence/mobile camera and mobile media player.

cr4cX H-Bridge

The cr4's H-Bridge is builded with MOSFET and BJT transistors and specialized low-side driver IC.

In my tests the bridge has worked at 32KHz PWM frequency with virtually no heat generated.

Two of these (one for each motor) are used in cr4.

The bridge prevents the shoot through conditions and allow the following operating modes:

  • pwm cw rotation
  • pwm ccw rotation
  • pwm brake
  • brake
  • coast

Maximum supply voltage is around 18V and maximum current through the motors is limited by the IRF9540 MOSFET caracteristics.

"Kicad is an open source (GPL) software for the creation of electronic schematic diagrams and printed circuit board artwork." I have used Kicad to draw a lot of … Read more

Motor sizing problem - Online calculators

Hi everyone,

I need two motors for my new robot and I used two online calculators to make the motor selection:

but I've got different results.

My input data:

  • mass 7Kg
  • 2 drive motors
  • wheel radius 0.037 m
  • velocity 0.38 m/s
  • acceleration 0.2 m/s^2
  • efficiency 65%
  • maximum incline angle 20 degree

Results: