Nicot31

The purpose of this project is to create an autonomous mobile robot that can move avoiding obstacles. It includes the mechanical construction , electronics and computing.

The main items that have drived this production:

• Keep it simple with modest goals 😉
• Minimize costs of realization
• If possible make obstacle detection. It’s always nice to avoid an obstacle rather than typing in.
• Use of this project to get back to electronics and real-time programming (subjects studied long time ago now…)

After searching the web, my choice for the heart of the robot was a PIC 18F Microchip microcontroller. An opportunity on eBay made ​​me buy a PIC 18F4455 that seems to be a very good compromise for this kind of projec,t with many capabilities for extensions or new versions of this robot.

For obstacle detection part, two choices are possible:

• Use of a distance sensor based on the infra-red
• Use of a sensor based on ultrasonic

I selected an ultrasonic module “ Ultrasonic Sensor URM37 ” that integrates on a single card the transmitter and the receiver. The interface is done via a RS232 serial link, so easily testable directly with a PC. This module can be found in England for £ 12 ( http://www.droboticsonline.com for example). This module documentation can be found here.

It also has the advantage of directly interfacing a servo control by generating the pulse trains required for angular positioning of the servo, according to the parameters and commands received on the RS232.

If you install this module on a servo, we can easily analyze the space around the robot to detect obstacles and to move towards a free area.

To display information during the development to help the debug (distances, error messages …) a small LCD display is added. I selected a 2 lines of 16 characters LCD. It does not display a lot of information but is a very economical solution (about 5 € on eBay). Documentation for this LCD can be found here.