Bunny house on wheels

Other Hardware Motors, Mechanics, Power and CNC
1

Hi everybody,

Let me expose the subject.. Do you know that the organic way of growing bunnies is to have them eat grass and have access to it ? Well that's why my dad made cages with fences and "rollers" to move them around a while ago.. only I thought it could be funny to add a battery with a solar panel, a set of four driven wheels and an Arduino to "pilote" them on straight lines at first, and maybe make more complex trajectories in the future..

I will be fine enough programming the whole thing and defining the necessary power supply.. only.. I am not at all an engineer in mechanics and get quite lost figuring out how much torque, gear ratio and else I may need... :frowning:

I would like to use the smallest motor steppers with proper gear ratio on two wheels so that it can move, but definitely slowly with like maybe doing 1 revolution per minute or so.. I actually need the cage to move only 1 to 5 meters per 24 hours... I would define the "speed" myself afterwards, just by playing on the frequency at witch I would have to make a new rotation (stepper = easy, and from what I've seen better torque motors)

I think the cage would be up to 100kg once everything on it.. well I mean.. I hope it will not be more than that !

There may be some elevation to take into account, like maybe 10-20% so that the whole thing would be able to climb a small hill for sure and in the best world with enough gear ratio and external forces due to the grass holding on the sides, the cage while not under power would stay put.. an not fall away.. with poor bunnies "faceplanned" inside it :frowning:

I'll take all the help I can get, and if in the meantime I can understand better the reflection and explanation behind it all it would be great :wink:

There may be some missing data, I am not necessarily looking for something exact but like enough to make it work if it was maybe 1 and a half more or twice the payload..

Thanks a lot, looking forward to hearing from you

PS: the words I am using may not be too accurate - if so I am sorry... I came to this world as a Frenchy :slight_smile:

2

Fun project!

Stepper motors are a very poor choice for such an application, as they are very inefficient and draw full power even when not stepping.

I think the cage would be up to 100kg once everything on it.

This is a large robot. The most difficult part of this project is the electromechanical part. Find suitably powerful brushed DC gearmotors and solve the wheel drive and motor power problem first. Beginner tutorials on wheeled robots can be found at http://www.societyofrobots.com/, which will help you with the calculations.

The rest is straightforward.

3

There have been other Threads on the Forum about robot lawnmowers :slight_smile:

Yours sounds like a slower version.

A moving machine that weighs 100kg could do serious injury to a human. Think what it might do to a rabbit.

...R

4

Glad I’m not a rabbit

5

4 geared motors the type they use to make powered skate boards. There are motors with gearboxes that will only do 3 revs per minute and you can gear that back even further with a chain drive reduction setup up. Does it have to move continuous or can it move 25 centimetres in 10 minutes then stop for 50 minutes. If it can move then stop you could add a raise and lower mechanism so that it raises a few inches to move then Lowers to ground after movement has stopped to prevent escapes and predator entry. Work out the weight and the maximum amount of movement required over time ( work out an acceleration value ) and we can find the force required to move it and from there we can find the torque requirements and then we can find the right motor and gear combination

6

This is a great idea. Will follow this thread.