RaspberryTortoise

The RaspberryTortoise is a project aiming to develop a motorised roving vehicle from readily available components and a Raspberry Pi single board computer(soon to be readily available).

Status

This project is in the concept stage. We are down selecting components and looking at feasibility.

Current Objective

To interface the Raspberry Pi GPIO to control the vehicle.

Ambitions

This is a list of the things we hope to achieve with the Tortiose.

1. Network enabled communications (wifi & SSH)
2. Web enabled controls
3. Visual Feedback (camera)
4. Semi-Autonomous operations
   1. Object Detection & Avoidance
   2. Environment Exporation and mapping (GPS?)
   3. Area Patrol

Concept Design

Platform

The chosen platform for the RaspberryTortoise is a BigTrak [1].

BigTraks were a popular motion-programmable 'robot' vehicle originally released in the late 1970s through to the 1980's.

These vehicles have been making a come-back as a 'nostalgia' toy. The are relatively cheap and contain all the key components needed to make an working robot. Prior work has identified the major components of the original BigTrak were simple[2], it is assumed that the modern device is similar. This project aims to modify the control system to inteface with the Raspberry Pi.

Work in progress

Power Requirements

The RPi is known to run off 5V[3] it should also run off 4xA batteries, up to 700mA is required to operate the device and any attached peripherals. It is understood that should the RPi draw more current that thermal fuses will kick in to protect the device from damage. If greater than 700mA is required the RPi will not be able to deliver it and an external supply will be required.

We do not yet know the power configuration of the modern BigTrak, the original vehicles run off a 6V power source provided by a stack of batteries [4]. Its seems reasonable to assume the modern version will be the same.

Adding an RPi and associated peripherals is expected in increase the load such that more battery capacity is required to achieve 'reasonable' run-time.

Before the power management can be decided at least one modern BigTrak needs to be investigated.

Power Sources

• Possible rechargable batteries [5][6]
• Solar Cell for daylight operation or to recharge / top-up battery [7]
• 5V 11000mAH battery used in other RPi projects [8]

Vehicle Interface

• How to interface the RPi to the motor controller and sensor board.

Network Connectivity

• WiFi - so we can SSH in to the RPi to issue new commands etc.

Sensors and Peripherals

• Camera. Ideally the RPi camera module which is currentl still in development phase [9], but any RPi supported webcam should do.

Shopping List

1. Platform, BigTraks on Amazon UK
2. Wifi Dongle, Tiny Wifi Dongle on Amazon UK
3. Battery, TBA
4. Camera, TBA

References

1. http://en.wikipedia.org/wiki/Big_Trak
2. Big Trak Reverse Engineered by Robot Room
3. http://www.raspberrypi.org/archives/260
4. Robot Room Big Trak Motor Drivers
5. Possible Rechargable Batteries
6. More high capacity but expensive batteries
7. Solar Recharging
8. 11000mAH battery
9. RPi Camera module

Resources / Research

1. PCB manufacture
2. Battery Chargers