Need for SPEED.....

I am trying to build a wheelchair, for fun and recreation, not necessarily for everyday use around the house, more for speeding around town or cruising to and around the beach, that goes 18-25 mph (or faster??)... where a single full charge on the batteries would last 10-20 miles (or more??), (depending on terrain, type of batteries etc...). Controlled by joystick (variable on-the-fly speed adjustable), using 2 to 4, 12volt batteries for 24-48 volt motors, 14"to 18" wheels. On a CUSTOM built frame, that will be built AROUND accommodating the motors, batteries etc... so size of motors is negligibly important. Weight of frame and seat with batteries and accessories and rider and, depending on motors, will be between 300-450lbs. Can anyone give me some sources/resources for motors, controller(s), type of joystick to use, type of battery, battery configuration, etc... anything else you can think of that would make this work... there is a small market for this type of wheelchair for very active wheelchair users that would just like to go tooling around town in their wheelchair rather than loading up their car or van just to go to the store or movie theater or to accompany a bike rider. Torque isn't a huge issue, mostly rolling on city/country streets with slight inclines but every once in while maybe encountering 30 degree grade for a couple hundred feet or so. I'm good with mechanics and have expert welders helping me out for the fram design. I'm a quick study and know some basics about electroncs and such... I'm not gonna say money is no object, but I do have some seed money to get this project off the ground keeping in mind this will be a prototype and if the end result makes viable a production model there will be more fundinding available for better parts and better technology. I just need some expert advice and direction to go to purchase the materials needed for the "specs" I've described above. Any help or input would be greatly appreciated, of course any questions will be answered to the best of my ability... I can be reached at 8309280770 in Texas. Links to resources for motors, joysticks other equipment needed etc... can be posted here or sent to <A href="This email address is being protected from spambots. You need JavaScript enabled to view it." target=_blank>This email address is being protected from spambots. You need JavaScript enabled to view it.... (I'm pretty sure you'll have the controller(s) needed right here).

You have some pretty tall orders in there man. Between the speed, weight and "occasional 30 degree incline" it's a tall order to be sure.

Electronic drive line simulator from enigma industries is a pretty good/painful way to blow $30... I would really suggest checking it out as it will do a lot of the math you need to get some ideas of what you need specification wise for motors / batteries...

IIRC it predicted that my setup -- 2 parallel 12Ah 12v AGM batteries, Magmotor S28 400 running a single 10" wheel at 3:1 -- would go for ~12seconds flat out at ~37mph...

What I can tell you from real world testing is that it will go up a 4.8 percent grade for around 1000 feet before the battery's are drained to the point where it will not climb the grade without the voltage dropping below the threshold that I need to keep the controller alive (12v). Or put even less scientifically: I get two runs up and down the hill in front of my house.

Obviously you can cram a lot more batteries in your project so your much better off... But don't underestimate the need for proper suspension if your serious about going 20+ mph.

I would look at some of the electric assist recombinant bike projects that various internet peoples are working on for some technical inspiration.

I'm coming up short on links at the moment but I'm pretty sure I originally found a few through www.hackaday.com under transportation hacks.

You really can't go wrong with one of the higher capacity Roboteq controllers though... Just plug in an standard RC radio for unmanned "flight" testing... And swap it out for a joystick when your ready to get behind the wheel yourself... And about a 20 other good reasons too :-) But I figure you know that or you wouldn't be here.

-PM

downloaded the "Demo Version" looks awesome... tried to purchase the full version their site is screwy... won't let me... tells me:

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Oh well... I wrote their email...

I would take any advise I can get... change the parameters to fit whatever would work to get me at or above 15+mph... Roboteq isn't even answering my email... is what I'm asking or any portion of it impossible to achieve?

Nothings imposable if money is no object :-)

I'm thinking it's pretty doable... But it's not going to be cheap at all... The roughest thing that I saw in your list was the 30 degree grade... That's just huge... Before I measured it yesterday I would have put my street at 15 degrees... But it's not even close.

As far as the rest... It's just the high speed stability that concerns me but that not a really big deal, just a matter of fine tuning everything... I mean there are plenty of quads and other ATV type wheeled vehicles that do it. But you are going to need some kind of suspension and that can kind of complicate the drive line a bit because the motor has to move with the wheels or needs a tensioning system....

Check out robotcombat.com for some of the hard parts. Gears pulleys and the like. I'm assuming your familiar with NPC already, they make a lot of the power chair motors and such... Another option would be the magmotors like I'm useing... They seem to be nice match for the AX2550. Me and the board weigh about 310lb total and I'm not anywhere near maxing out the power.

If you really have someone helping to defray the cost then seriously consider LiPo or LiFe batteries... Many chinese supplyers seem willing to ship to the US in low quantity but they are still expensive. I think they will probably be key to the range you need though. One of the gotchas' that I didn't find out about right away was that if you pull lots of current it won't last anywhere near as long as if don't. As a simple example if you have a 12Ah (Amp hour) battery you can probably pull 1 amp for close to 12 hours out of it... But if you try and pull 4 amps out of that same battery you will get much less than the 3 hours that simple math would dictate. This is much less of a "problem" with LiPo's. While enersys recomends takeing no less than 3C or 4 amps per hour out of my batterys you can easely find LiPo packs rated at 10 - 15C...

You have to be a bit patiant with RoboteQ... Good folks but bussy... The more specific you can make your questions the better. And they do have a ton of documentation for their products. Everything from wireing diagrams to white papers on regeneration. If your serious, grab it and read it all :-)

ok...<BR><BR>Maybe 30% was a bit of overkill... there is ONE hill here that is like that... and I don't HAVE to go up it... LOL... (but going down it is pure fun).<BR><BR>I can tell you I have $2000-$3000 to do this... I already have a frame... and the capability to redo/remake that for any application for next to nothing cost-wise... so the 3k can be used solely for motors/controllers... The frame DOES have suspension and can be upgraded accordingly to meet the need... <BR><BR>My biggest problem is this... I would like to be told... use motor model #****, and controller model#****, and joystick model#****... and I'll take it from there... when I can go look at those models... see their specs... or on the other hand... tell me what specific specs to look for... then I can go and shop the models myself looking for the specific specs or close enough to them as I can get... then we have a meeting of minds... and I can meld this all into one package... BADA BING!! Mission accomplished... <BR><BR>I'm pretty sure that controller AX2550HESC or AX2850HESC is the right controller to use... am I wrong?? So if this is the controller is right (or tell me which one would be) which motors Model#, where to purchase.. or specs I should look for in a motor that would achieve my goals... (or close enough to be realistic), and then also which joystick would be ideal to effect this ... <BR><BR>Mostly I'm using this to go down straightaways on the side of small highways in my area in the bike lanes... and to go into stores like Wal-mart or the mall... or load it up and go to the beaches on the Gulf Coast, (changing over to balloon tires of course). They are drive on hard-pack sand beaches so I could really let loose there... As far as Batteries go... Group 24 or Group 30 batteries start at 90Ah... and there are some batteries that go upwards of 165+ Ah's... 2-4 of these should be plenty... I'm even thinking about carrying 4 batteries... running at 24 volts... going somewhere, when the first two batteries run down switch over to the other two and then I'd know I can make it back home... The frame will accommodate this for sure...

One other thing... if I can make this work... and people I meet or whatever get interested... I would like to build this for other active disabled people... I'm a disabled Vet... and know several others already that would put out the bucks to have a wheelchair that would even come CLOSE to what I'm proposing... Of course only I would have the fastest... *hehehe*<BR>

BTW, where can I find the LiPo, LiFe batteries... just to research them<BR>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"><meta name="ProgId" content="Word.Document"><meta name="Generator" content="Microsoft Word 11"><meta name="Originator" content="Microsoft Word 11"><link rel="File-List" href="file:///C:%5CDOCUME%7E1%5CADMINI%7E1%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"><!--[if gte mso 9]><xml> Normal 0 false false false MicrosoftInternetExplorer4 </xml><![endif]--><!--[if gte mso 9]><xml> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> <p class="MsoNormal">Ah... I did misunderstand grade... I think my hill is ~5 degrees so that gets me something like an 18% grade if I'm doing the math right (Assuming 90 degrees = 100% grade).

That aside you really can't go wrong with the top of the line controller. And you can use it to get some data as to what the max current required for future models.

I think if you can afford it the closed loop mode in the 28XX series would be very nice. It will let you keep your speed consistent over uneven terrain. You basically add a $30-50 wheel speed sensor onto the back of each motor and once properly tuned (largely a matter of trial and error as I understand) your joystick functions as a 0-100% throttle, rather then 0-100% power. Not having used a power chair before I'm not sure if this would be desirable or not, but it might be neat to play with on the first one.

If your just looking for a recommendation on motors I would say you can't go wrong with the Magmotor s28-400 from robotcombat.com. You will need to do your own gear reduction, figuring out the ratio you want is where Electronic Drive Line Simulator will come in handy. I run a 10" pneumatic go-kart tire on the back of my skateboard geared at 3.7:1... That should get you the speed you are looking for.

Driveling them with the batteries you describe should work nicely... Just keep in mind how those Ah ratings are based on pulling 1 amp out of the battery from whatever the rated time is. So a 90Ah battery will (theoretically) run a 1Amp load for 90 hours.... But it will run a 90 amp load for probably 20 min... And the battery will not last long this way... But you should pull no more than 10-20 amps nominal -- I'm guessing here based on my ~300 lb setup pulling around 12 - 18...

The other nice thing about the magmotors is the mounting brackets that you can get... Very sturdy and nice looking. Though Team Delta makes some even better ones.

As far as a joystick goes... I just can't help to much... I know there are some links off of roboteq's site Penny and Giles I think... The manual has the correct range, but I think something like a 10K joystick would be good. Pick any style that suites.

They come in two flavors, Hall Effect or Resistive... The diagrams in the Roboteq manual correspond directly to the Resistive type.

This stuff is just a hobby for me, I'm not an engineer so take my advice as such... But I have used most of the parts I've discussed so the advice should be solid but if you electrocute yourself or something, it's not my fault :-) And do be careful... It hit home from me when I was learning to arc weld parts of my project and we used something like 25 amps of current to weld 1/8" aluminum plate... And I was pulling 90 + going up hill. Anyway, don't mean to get preachy or anything... But it's always worth remembering that it only takes hundredths of an amp to disrupt a human heart rhythm.</p>

AWESOME!!! Thank you Thank you Thank you...

That is EXACTLY what I am looking for... I'm off on my QUEST!!

Dataac99, If you or anyone else reading this thread have anymore suggestions or advise, Please don't hesitate...

I'll keep you psoted on my progress and results...

Thanks again!!!