Servo - November 2016

However, we have to move beyond that, so let me introduce you to Berry Bot.

For more complicated bots, at some point, we have to add the ability for it to navigate at least around the house. We could use a GPS module if we were outdoors, but GPS modules are fairly useless inside a house or apartment due to the limited resolution and — even worse — poor GPS reception indoors.

Inside, we can use a variety of beacons and distance sensors in order to give the robot an idea of what room it is in, and how close it is to nearby objects. That information is greatly enhanced by adding a compass. Once we can tell how far we are from objects and what direction the robot is facing, we can start trying to implement some mapping functionality which can later be used for indoor positioning and navigation.

If we are going to investigate indoor navigation, it would be nice to give the robot some more brain power and the ability to add more sensors ... which leads to more batteries and more weight. So, first let’s improve the drive system.

An improved drive system needs a more powerful motor drive, which dovetails rather nicely with talking about the popular L298N based motor drivers. For this article, I decided to give Hobbit a holiday and talk about Berry: my new 4WD Dagu red chassis based bots.

Berry is more “brainy” than Hobbit, and can carry more weight. Berry currently consists of:

1. Dagu Magician 4WD chassis (red)

2. Raspberry Pi 3

3. RoboPi robot controller

4. L298N driver module

5. HMC5883L magnetometer module (compass) 6. Sharp IR distance sensor

7. 9g servo for panning the Sharp IR sensor

8. Patriot Fuel+ 5,200 mAh USB power bank

9. 4xAA battery holder for motor power For the time being, Berry will not be provided with a camera since vision processing is a very complicated topic. Plus, a camera is not necessary for initial indoor location experiments.