Hello all,
Greetings from Atlanta!
I am new to the group and excited to see the progress that has been made in 5 short years of ardupilot development!
Just watched Andrew Tridgell's talk about porting onto an embedded linux platform with multiple sensor redundancy and this is exactly what I have need for right now.
What I actually want to build is a vehicle that is mainly competent in water as a boat, but can haul itself onto land if need be and drive onto a trailer, or move to safety in the event of a storm, etc etc.
After some test models, I would like the eventual craft to be 10 feet or more in size. I am part of a collaborative to build non-profit low impact water based farms. The vehicle in question will hopefully be an automated platform for monitoring aquaponic farming. and needs to be able to carry robotic arms and multiple cameras, etc.
I would also like this to be a quad propeller/wheel vehicle with each wheel capable of independent steering to allow the vehicle to park itself sideways next to a dock when in the water, or move like a crab on land. :-)
Land speed doesn't have to be anything more than a couple of mph/kph... this is just for simplicity of maintenance and moving the vehicle to other bodies of water.
Does anyone know of anyone that has built anything even close to this that would be a good starting point as a collaborator?
Has anyone built a craft (land or water based) that can rotate each of it's steering wheels/props independently with 360 degrees of directional travel?
Many thanks for any and all help/suggestions.
Ricky
Replies
@Ricky,
The vehicle you describe is like a WWII Duck that had twin screws for propulsion in the water and 6WD wheels for land use.
However, you might want to consider building a twin pontoon vessel that would have retractable thrusters for in the water and some form of retractable power wheels that could be lowered into place to propel the vessel when it is out of the water.
Having retractable power wheels would negate the need for waterproof shaft seals if the power wheels were located either on the side or under the vehicle.
Regards,
TCIII AVD
Ha yes Thomas .. I am aware of the ducks. They actually still run them for the kids on the lake at a local park so I get to see them on a regular basis. :)
The duck is not really what I had in mind.
My thruster/wheel legs would operate in an outboard fashion in the four corners of the craft (at least in my concept). This way they could be latched onto an existing boat hull without having to compromise the hull. Each corner would act as an individual thruster to push the craft in all directions, which would give unparalleled maneuverability.
What I was hoping to do was to keep my systems modular and identical so they could be "hot swapped".
. In my concept, the legs would also be able to be retracted from the water for maintenance/cleaning. I am not sure if it makes sense to have the wheel permanently attached to the same thruster legs,
It may make more sense to have just wheel hubs on the thruster housing that have either a shared or independent drive train.
The legs could then be retracted to either add or remove the wheels as needed.
That side of the engineering is still to be established. What I really need to know is if anyone has created controls/code for 4 wheels that have independent directional capability in 360 degrees. The ability to have the craft go sideways on water or land is my key concern here.
(essentially the same function as a bow thruster, but all operating from the four quad legs).
I thought maybe someone may have built a rover/robot that can operate in very tight confines by having all the wheels be able to move 360 degrees in steering.
Does this make any more sense?
I could perhaps throw together a concept sketch and upload it if it doesn't.
@Ricky,
Presently the ArduRover2 firmware only provides either normal steering/throttle or skid (differential) steering.
You would have to investigate the use of Mecanum wheels Link and the firmware necessary to get them to function in the manner you require.
You are starting a very ambitious project, to say the least, and I wish you the best of luck.
Regards,
TCIII AVD
Hey Thomas,
So noooo ... definitely not thinking of getting into the Mecanum wheels! Like you said.. way too ambitious and expensive for my needs.
I know that this project is a little out of the norm, and having done a little more reflection, I think it would look more like this (but on a much bigger scale)
http://lcamtuf.coredump.cx/omni2/
4 wheel steering
So, like this model, I suppose that the wheels really only need 90 degrees of rotation really, not 360. The above link has all the wheels linked by a mechanical link. That wouldn't really work on the scale I am thinking tho, so the steering would have to be broken out into four separate turning mechanisms.. e.g. servo/stepper motor.
(sorry, I am not much of a coder so I really would have no idea what to look for to get going)
Thank you again for your help!