ControlMecanumNAVIORaspberry Pi

Indoor holonomic rover with NAVIO2 and Wifibroadcast

I’ve thrown together a quick mockup of a holonomic indoor rover using an F450 base plate, some CF tubes, a bunch of micro DC motors and my NAVIO2 setup, with a TL-WN722 wireless card.

Holonomic rover mockup

I’ve used the Fingertech Mecanum wheels, but I was quite disappointed at their design and build quality; long story short, I had to spend some time with the Dremel grinding to get them to an acceptable shape, and they still don’t run very smooth. Well, food for thought for a future upgrade.

Fingertech mecanum – on the left the original wheel which runs terrible. On the right, I grinded the edges and used shrink tube instead of c-clips to reduce edge contact with the ground

I’ve also taken advantage of the new NAVIO2 image to set up Wifibroadcast, controlled by an RC switch, as I demonstrated in my previous post.

I’m using my own (basic) control routine in Python, interfacing RC input to PWM output, with the help of the examples offered by EMLID and a bit of basic math to assign rotational velocities to each of the four wheels, so as to achieve the desired movement. The rover runs quite smooth, but it could be made better by tapping into the gyro and accelerometer, to give it a truly locked-in heading.

I’ve got big plans for this; my next major aim is autonomy. I see potential in projects such as donkey, which aim to bring vision-based autonomy to small ground vehicles. So I’ll keep yall posted on this.

I’ve made a couple indoor videos, so as soon as I find some time I’ll make sure to share.

1 Comment

  1. Pingback: Build an autonomous car with RPi and Donkey, part I: The hardware – Unmanned Build

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