Blogs

Name: Box-T

Function: Patrol Robot

I put Box-T together to keep an eye on my garden. We’ve got a variety of creatures that like the vegetables as much as we do, so when a creature comes into the garden, it’s Box-T’s job to chase them out.

He's not pretty, but I can disassemble and reassemble him in minutes, and I have a lot of options for easy expansion.

The Environment:

As you can see in the picture the garden is a matrix of raised beds.

This picture was taken in the spring so things were just getting started. Next year there will be another row of raised beds to the left, making the garden a 3x4 matrix of raised beds. As you can see there is a lot of forest behind the garden. Many animals reside there. Box-T's job will be to keep the animals from making the garden their lunch.

Platform Configuration: Box-T is 4-wheel drive robot that makes use of differential steering (tanks steering or skid steering) to turn.

System Architecture: The system is based on the APM 2.5 and Ardurover code, but I decided to trim a lot of the things I didn’t need. I didn’t need the IMU and pressure sensors. I could do with out the data logger. I have plans for one, but at the moment, I don’t need an on-board one. I also wanted to use an off-board compass and GPS. I also decided to dump the PPM encoder and go with a hardware PPM Mux.

With these things in mind I decided to go back to basics. I already had an Arduino Mega 2560 that I was playing with so I decided to rebuild my autopilot off of that.

Arduino Mega 2560 with custom shield

To date the system has the following components:

-         Arduino Mega 2560

-         Custom shield with a hardware PPM mux

-         Dimension Engineering Sabertooth 2X12 Motor driver

-         3DR GPS uBlox LEA-6

-         3DR HMC5883L - Triple Axis Magnetometer

-         Airtronics 92824 receiver

-         Two (2) SRF05 sonars

Software Architecture: The software is based on the APMrover 2.20a firmware, but here again, based on the significant modifications I’m making, I've decided to trim up the code and remove the features that I don’t need.

I'll post schematics and code as soon as I have everything tested out.