RC Power Chair

[Budrowe]

I'm new to this Board and this is my first message. In fact, this is the first time I've ever tried one of these things. So, please excuse me if I'm not getting things right. I found your site while searching for some informaiton on power chairs. What caught my attention was the Omni Plus interface. I would like to have detailed informaiton on how to install the Onmi Plus and where the device can be obtained. Also, any more information on building RC chairs. Can anyone point me to a web site or give me more information on the subject? Thanks for any help.

[Burgerman]

www.pgdt.co.uk or .com for a US office. Omni plus.

There isnt a website.

If you want a cheaper more effective easy to do and with free programming capability solution use an HDC 2450 Roboteq instead... http://www.wheelchairdriver.com/BM-MK3-roboteq.htm Watch the video.

[Budrowe]

OK, Thanks man -
Although I have some experience working with electronics (ham radio), this seems a bit complicated with no more instructions available.
Thanks for the reply.

[ex-Gooserider]

I would suggest reading the stuff that BM has already posted on the main site, several times if need be, and maybe try drawing out some schematics or block diagrams... It is not as complex as it seems, mostly it's a matter of plugging the right bits together. As a ham you should be ahead of the game for part of it, and you can probably get plenty of help if you go to a good RC hobby shop, or perhaps one of the RC interest websites...

ex-Gooserider

[Martin O Refurbisher]

Welcome.
If you like to add your location to your profile, you will get more specific localised help. If you understand ham radio, you will find RC a doddle.

Best,

Martin

(ex G8AIP)

[Budrowe]

Hey thinks guys for the replies and please be patient with me. I am very comfortable with the computer but, as I said I have never done a message board before. I seem to get lost when I try to navigate around here.
For Martin - Where do I find the "Profile"?
For exGooserider - Who is BM and where is the main web site?
A little about me, I'm in Tennessee. I was born with a disability and used crutches until 1995 when I injured my back and had to add a wheelchair to my method of transportation. I have gotten more active since retiring and picked up an old powerchair to use around in my shop. RCing this thing would come in handy for several reasons.
Thanks again for the replies and I have several other issues I would like to discuss but am concentrating on the RC thing for now.

[Burgerman]

http://www.wheelchairdriver.com/ main site home

http://www.wheelchairdriver.com/powerchair-stuff.htm menu of powerchair related stuff - including how to RC one...

[ex-Gooserider]

Hey thinks guys for the replies and please be patient with me. I am very comfortable with the computer but, as I said I have never done a message board before. I seem to get lost when I try to navigate around here.

This is a fairly standard board, most Internet forums tend to use this or something close to it (phpBB is free software, and a lot of the non-free systems use it as a starting point) It takes a while to learn your way around, but it gets easier with practice. It isn't necessary, but if you want, the closest thing to a manual is to click on the "FAQ" label up near the top right of most screens.

For Martin - Where do I find the "Profile"?

The Profile is reached by the "User Control Panel" label near the top left on most screens - this is where you can fill in a lot of information about yourself, and do things like change your password. It is also where any "PMs" or Private Messages will end up or get started - this is a way to send messages to just one member if you want to talk about something that the rest of the board doesn't need to see... The perfect example is if someone is selling something and you want to negotiate the price and shipping details - the rest of us don't want / need to see that so do it via PM's...

For exGooserider - Who is BM and where is the main web site?

BM = Burgerman = the guy that runs the place, and has created most of the site... He has created several different chairs, which you will often see us describe as the "BM Mk X" to tell them apart. Currently the Mk 1 isn't being used much, he is running around in a Mk 2, the Mk 3 is in the process of being built, and the Mk 4 is on the drawing board...

The main site can be reached by clicking on the "WheelchairDriver.com" up at the top of the page, or go to the links that BM posted in the message just before this one. The main site is the place where BM has posted a lot of detailed info about his chairs and all sorts of other stuff ranging from vehicles to various chairs he's tried to how he has set up his home to deal with his disabilities (IMHO, not a bad place to start from for lots of us) It can be a bit of a challenge to find your way around, but all of it is well worth reading, several times...

A little about me, I'm in Tennessee. I was born with a disability and used crutches until 1995 when I injured my back and had to add a wheelchair to my method of transportation. I have gotten more active since retiring and picked up an old powerchair to use around in my shop. RCing this thing would come in handy for several reasons.
Thanks again for the replies and I have several other issues I would like to discuss but am concentrating on the RC thing for now.

Don't be afraid to mention your other issues. The RC stuff is somewhat unique in that it can be added to a chair independently of other stuff, but even with that, it often helps to take a "systems approach" to the question. For instance, the way the RC gear will interface depends somewhat on just what you have for a controller on the chair - if there is some reason you might want to change the controller, then you might want to hold off on doing the RC stuff in order to avoid having to redo it later... On a larger scale, how do you like the current chair - if you want to make a lot of changes, then it might be worth looking for a chair that offers a better starting point for modification...

[Budrowe]

The RC stuff is somewhat unique in that it can be added to a chair independently of other stuff, but even with that, it often helps to take a "systems approach" to the question.

Is there a "Good" and/or "Best" chair or controller to do the RC conversion with?

[Burgerman]

Not really. But I can tell you that later on you will wish you just bought a roboteq!

You should be able to use the receivers output (to a servo) directly, as a voltage swing.

You need a small voltage swing. Although you need a RX that will run on 12v. Its output is pulse width at a specific frequency I think. The signal, and the black wire will give a analog voltage if you add a resistor in series, and a capacitor across the resultant signal.

The MID stick voltage should be half way between the pos and neg supply. This can be fine tuned with say 20k pots, to give correct voltage swing and correct centre voltage. The result will be fed into where the chairs joystick was connected. It works with an omni plus, never tried it with anything else.

[Budrowe]

I have an old power chair that was well used when I got it. I don't even know what brand it is but it works well and I have made some modifications to it.
It's very handy for around in my shop. I also have a Pride Celebrity XL that I use outside around my property. It's giving me some problem at the present and I'm trying to determine if its in the transaxle or the motor.
I took a look at the Roboteq site. I will study the site and the ideas you have given me. If you have any more ideas, info and/or suggestions please, send them along.
Thanks Again

[ex-Gooserider]

Essentially you are looking at an interface issue no matter which way you go. The problem is that the joystick pod communicates with the controller using a proprietary bus protocol (some variant on "CANBUS") so you either need to have an adapter that can take the analog outputs of the RC receiver and convert it to something the controller can understand - which is what that box BM is using at present does. Alternatively you can use a robotics controller, such as the Robotec unit, which can take the RC receiver inputs directly, but then you will need to work on the joystick pod to make it give an analog signal that the Robotec can use... Pick whichever you prefer...

ex-Gooserider

[Budrowe]

What is the "box BM" - a definition

[Burgerman]

On here: http://www.wheelchairdriver.com/radio-c ... rchair.htm

[Burgerman]

An alternative way to get a voltage swing from a RC reciever is just a single resister and smoothing capacitor.

Or use the insides of a servo, with the feedback pot a couple of resisters as a divider network for centering. The motor wires are then dc voltage out.

[Budrowe]

The photos are particularly helpful. Lets me see how things are put together.
I'll take anymore if you got them. Thanks

[ex-Gooserider]

Minor bug / broken link report... At the bottom of the page you link to above, there is a line:

There is a thread on the message board about how to do this radio controlled powerchair interface here!

The link doesn't do what it says, it just takes you back up to the top of the same page...

ex-Gooserider

[ex-Gooserider]

Back on the topic, I notice you have a nice photo of your new transmitter, which looks like a really nice unit, but appears like it might be overkill for the job of just driving a chair around... Presumably it has a fancy price tag as well....

If you (or one of us) wanted to get an RC setup JUST for driving a chair, what should we be looking for?

ex-Gooserider

[Burgerman]

Just a chair? DX7 Spektrum does 80 percent of what mine does.
Even a cheap chinese one would work, no mixing or anything required just for a chair. But you wont use it just for that when you see all the ready to go cheap flying toys, planes, helis, UFOs etc that are available! They are just needing a transmitter!

Yes mines about 1200 dollars! A bit overkill for a powerchair but useful for planes and helicopters. Even a foam ready to fly glider needs 6 or 8 channels if you mix ailerons and flaps, dive brakes (crow) as anti speed/ spoilers etc. That wing has four servos to control its servos independently. Plus rudder, elevator, throttle. Thats without any spoilers... Thats 7 channels. And you will want to play.

[ex-Gooserider]

Wow - seems like they've gotten a lot fancier! Never got into RC stuff but had a friend back when I was in High School (1970's) who did a fair bit of it, and showed me some of his gear... As I recall, all fuel powered engines, and 4 servos was fancy.... (and increased the odds that someone would stomp on your transmission and make your plane or boat do strange things....)

ex-Gooserider

[Burgerman]

Now interference is a thing of the past. They use 2.4ghz, more than one channel at once, frequency hop, talk to each other and negotiate, and no need to check frequencies.

No need for oily methanol and nitro any more. Electric is FASTER, Lithiums, and brushless can beat the engines pretty comprehensively.

I fly these hotliner gliders: http://www.youtube.com/watch?v=Y6vWavvB ... ure=fvwrel this one is about 700 watts.

And also 60mph faster F5D pylon racers. About 1100 watts!
Its why I dont have much trouble with joysticks...

And I fly jets, pulse jets as well as turbojets like this (no messy oil to clean!):
http://www.youtube.com/watch?v=dTHWBSlu ... re=related

[ex-Gooserider]

Impressive! Just out of curiosity, anybody get an RC model to go supersonic yet? Would seem like you could get the power to weight ratio down enough that it should be possible...

ex-Gooserider

[Burgerman]

No. Because of a chap called Reynolds... I think the fastest is about 400mph, turbojet powered. But 200 (even scale stuff) to 330 or so mph for sporty stuff is pretty comon nowadays with the right powerplant and model. Even at some small club sites. You wouldnt want to be stood in the way.

Jet engines with 20kg of thrust are common. More is available. Keeping them in fuel, and physical strenght in flight as well as control surface flutter are the big problems.

[Martin O Refurbisher]

Videos are impressive - I recall a Reynolds Number, but not what that has to do with speed limiting of models?

Best,

Martin

[Burgerman]

Basically it means you cant scale down the air molecules. So the smaller the aircraft, turbine wheel, etc, the more drag, less lift, less thrust, you get etc. In other words the smaller the engine the less efficient it is. The smaller a wing is the less lift (proportionally) it produces, needing more angle of attack, more drag etc.

As such a full sized airliner has 1/5th of its weight as it has thrust. It does 500 mph.
A smaller model with 2x as much thrust as it has weight (ten times better power to weight ratio) can climb vertically straight up at very high speed but its top speed is still say 250 mph. Ie its speed is pretty constant.

[Martin O Refurbisher]

BM
Thanks, thats very interesting! Have you ever though of the size wings and power plant needed to turn a powerchair into a real cockpit?
i.e. create a chair based microlight?

Best,

Martin

[Burgerman]

No... But a heli yes!

[Martin O Refurbisher]

BM
Can we build it?

Best,

Martin

[Burgerman]

Why not. It will probably hurt while doing development work. But I understand helis. Not so sure about safety though!

There are plans for these all over the net. Nothing complicated. It needs scaling up to account for a lightweight lithium powered powerchair on the bottom.

http://www.youtube.com/watch?v=2W3gamijezc