Hello there.
My team and I are looking for an Ardurover setup example to be used as a test bed for our flight control, communications and camera tracking.
We focus on drones, but we figure that a rover is less likely to crash, so we’d like to build a rover for some simple testings.
I’ve looked through many many posts here and on Google in general, but couldn’t find a described setup with a pixhak-like ‘brain’ running omni directional rover (except for this one, which uses an unknown toy chassis).
For example - the mecanum wheel chassis in AliExpress come with motors with built in AB phase encoders which Ardurover cannot support more than two of.
If someone can provide an example, or even give us some guidance as to “what works with what”, we would greatly appreciate it.
P.S our goal is no drive the vehicle through Manual mode with a companion computer, without using MavLink in the middle.
Since Ardurovers support of omnirovers is not quite there yet, you will not find many examples for them. If you are going to use only manual mode, the Pixhawk becomes just an overpriced motor mixer. None of the sensors it has or Ardurover running on it will provide any benefit.
An arduino will do the same with a bit of programming and cost less. You will also be able to use a second arduino (or perhaps something faster, like a bluepill) to read wheelenconders.
The only benefit will be, that the Pixhawk is useable as a controller for the multicopter later, but then it will be much safer to use guided commands to control it.
There is no problem building the rover with a Pixhawk or another flightcontroller. I just wanted to make sure you knew what you will be getting.
I would go with a premade mecanum robot chassis with motor controllers that can be controlled by a RC PWM signal. There are some chassis that use the Tamiya plastic geared robot motors. Stay away from those and find a chassis with metal gear motors.
You can read the wheel encoders with a seperate microcontroller and use the data with your navigation software on the companion computer.
Our goal is to have the companion computer flying a drone on acro\rattitude mode, similar to this article, where the autopilot is on stabilized mode.
The companion computer will receive tracking information form a camera controller (its a gimbal+camera+controller package) and should follow a target tracked by the camera.
The rover will be a test bed for our companion computer, and hopefully will host flight controller and computing electronics as similar as we can to the drone.
@count74 Thanks for the heads up regarding plastic gears. I’ll keep on looking for a chassis with RC PWM capable motors, though I’ve scanned AliExpress and Amazon and couldn’t find any.
If anyone can recommend on a hardware combination for the parts from the Pixhawk to the wheels, I’ll be very happy to hear since I’m new to this area and I find it hard to understand it all in a short period of time.
I’m not sure if reading wheel encoders will give us useful information in our case since the rover would be a test bed for a computer-drone-pilot, i’ll bring the idea to the team anyways.
Amazon (Germany) has mostly useless offers. Over 300€ for a acrylic plate, 4 cheap motors and 4 plastic mecanum wheels.
The best I could find was this:
Use the chassis, motors and wheels and four (better buy one or two more) of these:
These ESCs should work with the motors mounted on the frame you linked, with forward+reverse?
I’ve seen posts around here saying that this might be an issue, just wanted to make sure.
Anyways,
Since it seems that an off the shelf solution is not avaiable and I’m goign to need to order at least 2 separate products, let’s try this:
How about RC Crawler brushed motors, combined with Omni or Mecanum wheels?
The electronics for these are widely available.
We can print or manufacture an adapter between the motors and the omni directional wheels, if needed.
This will also allow us to purchase 5 or 6 motors and ESCs to have spares available.
Planing for spares is a good idea, but an RC crawler motor is just a naked brushed motor without a gearbox. It will run much to fast with not enough torque.
You need a motor with an “inline” spur oder planetary gearbox attached, which brings the output RPM down to a few hundred or less RPM. The motors you are looking for are 25D or 37D sized. The ones in the chassis I linked are 25D.
The ESCs are the same I use in my mecanum rover. Fwd/Rev(what you need) with a switch for Fwd/brake/rev.
Buying everything seperatly will make it much harder to get a working rover, especially if you are still learning what works with what.
As Sebastian says Crawlers have a tiny pinion gear and a giant spur gear. Crawlers make for nice Rover platforms, it’s what I have after building some other types.