Input!

I've just added a couple of microswitches and a bumper bar as a cheap way of getting input. So now that it has sensors the robot can react and make decisions. So far I have it reversing on touching an object, doing a small turn and then moving ahead. It will do this until it clears the obstruction. In terms of I/O this chip is now fully utilised so the next step is a more capable chip.

Messing around

I have been experimenting with some of the commands that I imagine will be useful to my project (readadc, sertxd) and reacquainting myself with BASIC commands.

The breadboard approach to quickly constructing circuits for experimentation has worked really well. It looks a mess but is only needed for a short while.

I think I'm ready for the next step which is to buy an ultrasonic distance sensor to allow my primitive MK1 robot to have some input on which to act.

Robot Mk1

Well the robot will have to be mobile. I imagine eventually it will need to be tracked, but as a cheap and easy start point I've just built my first (crude) robot to gain a bit of experience in motor control.

So here is my first robot:

It's based on the Picaxe 023 motor driver board that uses a Picaxe-08 microcontroller chip to drive a L293D driver chip. The drive train in a Tamiya gearbox with Tamiya wheels. Power is 2x1.5V batteries.

Here are some photos and a video.

The video shows the robot making three types of turn using differential control.

1. A slow turn anticlockwise achieved by occasionally stopping the left wheel.

2. A sharper turn clockwise achieved by stopping the right wheel.

3 A sharp turn (rotate) anticlockwise achieved by running the wheels in opposite directions.

I did say it was a crude robot! I did find it useful however. I found the driver board did exactly what is says it does and not much more. For my next step I will breadboard the electronics to give me more control of the design and develop a bit more understanding here. I also want to explore PMW and think I'll move to a more capable controller chip (possibly the Picaxe 18M2) with more I/O possibilities for future development.

-Peter

Hi, First Post

I've just created this blog to record my progress with robot building.

Many years ago (~30) electronics was an interest of mine and throughout my working career I have done a lot of simple programming. The concept of unmanned vehicles has interested me over the past 5 years or so and because of this I have a vague idea of an sentry robot that follows a predefined patrol path and when it identifies an anomaly will alert an operator to take tele command of the vehicle.

This involves a lot of learning on my part, but that's the whole point! I envisage making many small robots along the way to become familiar with the implementation of various technologies and ideas. It's the journey and not the destination that's the fun part.