The Beast cometh!

For many years I wondered why no-one seemed to make wheeled robots with stepper motors. It seemed an obvious option to me but it was always small DC motors (or large ones of course) or altered servos that everyone used. While in my self imposed quarantine, I started reading up about steppers and I can still find no reason not to use them so...........

My Next Big Thing

is going to be an attempt to build a four wheel drive robot using stepper motors.

I'm not using large motors either, I shall be using 28BYJ48 motors with their associated driver boards because of their size, small, and their cost, cheap as chips. I have already run some tests and, whilst fairly slow, they are very strong with good torque and should do well for what I intend building.

Rather than drive them from a big complex system, I am going to try using Arduino Nano boards, one to each motor, and network them using I2c to either a Raspberry Pi or another Nano with a WIFI link. I'm not too clever at coding for the Pi so I will certainly begin with the Arduino.

I've begun by drafting  out a basic  concept for the body of the vehicle itself.

As it will be a four wheel drive chassis I want it to be fairly symmetrical with the wheels all the same size and only steering at the front end. It has to be big enough to carry all the electronics but not too heavy to be driven by the somewhat small motors. 

I also would like it to be fairly high above the ground in order to be able to take advantage of the large, 85mm dia, wheels and the high torque they will have.

And lots of prototypes are being printed for the body and moving parts.

Sadly, none of these will make it to the final product but most of the measurements are now fixed.

Sidebar #2 How I did it.........

The case is made of two 3D printed pieces, Front and Back with three 3D printed buttons. The box on the left is for a five volt power supply and that takes it's supply from the fig.8 socket mounted on the rear panel. The small hole is for the alarm sound to be heard. In addition, I have cut a small piece of acrylic that fits the display panel to keep dust out and make the whole look fairly professional, I hope.