[texswede]

Good evening everyone. I am looking to modify a power wheel electric car for my daughter who has cerebral palsy. The goal is to add joystick control for both steering and speed control. I am hoping to get some feedback from the experience on this forum for how to accomplish the conversion. My daughter is six years old and about medium size for her age.

First off, what vehicle would you all recommend to convert? I am looking for something that is roomy as I will be installing a special seat or adding a five point harness. I went to several local stores and looked at vehicles in person, here are a couple I am considering:

Power wheels jeep (CBG61) - the seats look flat (no center ridge) in pictures but I could not get close to this one as it was up on shelf. This seems like a popular model on the forums with a lot of knowledge out there.

Power wheels dune buggy - looks like it has space but there may be a ridge for the seats, but seat backs are high enough that mounting the special seat or adding five point harness should work. If anyone has experience with this model and can let me know how suitable it is for conversion that would be great.

Conversion:

I have experience with programming and arduino projects, but have not done quite something at this scale. I have read many of the threads on here and done research on other sites as well. Here is the idea I have for what to do:

Joystick potentiometer - to control direction and speed. Hooked up to analog pins on arduino to read direction (left vs right) and speed (forward vs reverse).

Motor controller - Sabertooth 2X25 V2 - has arduino libraries and examples. Read several threads on here about using this particular model.

Steering - Firgelli FA-PO-35-12 2 inch linear actuator. Picked the 35 lb model as it has a speed of 2”/s so that steering would be responsive. The potentiometer would be read for location of the rod. The actuator would be controlled by 2 Sparkfun Beefcake relays which has 20A max hooked up to the arduino.

Read on here that at least the jeep only needs 1 inch movement to reach full turn - is that correct?

For parental controls I am going to attach a bluetooth adapter to be able to override the car from an Android phone.

Does this sound like a viable plan?

Are the vehicles good choices?

Thanks

I posted in R/C since this board seemed to deal with electronics, specifically the motor controller and linear actuator a lot. Let me know if this was not the right place.

[MR_Pat]

Hopefully someone with a little more knowledge in this department will pipe in soon . Nice idea with the actuator. Have you looked into any of the Peg Perego models or maybe the razor polaris UTV ? my understanding is those vehicles are a little more stout and would maybe allow you more room for the added pieces you need to put on .

[CJB]

If you search "arduino" on this site, you'll come across a few projects where people made their own speed controls with the arduino platform. One of them even made their source code public if I recall. I've never worked with it, so I'm of little assistance otherwise. Same with R/C... no experience.

I'd also search "palsy" or "special needs" as there have been several projects done specifically for this type of thing.

[flipper]

Very cool idea. Far more ahead of the curve than I expected this post to be. Have looked at using blue Tooth controllers on a few car projects, but haven't gotten around to it yet.

Have you considered what size battery you are going to run, with all those functions and servos I would think a 18V or even 24V would be a minimum for any large amount of time. this may also factor in to which body you opt for as it is then much more able to fit.

I had 5 point harnesses custom made for my daughter by Percision stitching (facebook/instagram source) who made custom nylon ones that were adjustable from all points and so that it could grow with my daughter. She specializes in automotive performance styled stuff, so she did "bride" fabric to make pads for the harnesses like a true racing harness.

given what you are planning, I have to wonder if contacting the store and seeing if one of their displays aren't being retired soon (they usually just toss them) or hunting C/L as once you have added all of these things it is barely going to be a shell of its original self anyways and you are going to likely be doing some cutting so taking a brand new off the shelf unit might be a little wasteful (just something to think about).

less you consider starting off with something like this......

which would have most of the computer side it figured out for you already.

[flipper]

http://www.xtreme-toys.co.uk/ride-on-ca ... white.html

They are in the UK, but I would be willing to bet there is a way to get it to you

[texswede]

If you search "arduino" on this site, you'll come across a few projects where people made their own speed controls with the arduino platform. One of them even made their source code public if I recall. I've never worked with it, so I'm of little assistance otherwise. Same with R/C... no experience.

I'd also search "palsy" or "special needs" as there have been several projects done specifically for this type of thing.

I did as you suggested and found a bunch of valuable information - thanks for the suggestion.

[texswede]

Very cool idea. Far more ahead of the curve than I expected this post to be. Have looked at using blue Tooth controllers on a few car projects, but haven't gotten around to it yet.

Have you considered what size battery you are going to run, with all those functions and servos I would think a 18V or even 24V would be a minimum for any large amount of time. this may also factor in to which body you opt for as it is then much more able to fit.

I had 5 point harnesses custom made for my daughter by Percision stitching (facebook/instagram source) who made custom nylon ones that were adjustable from all points and so that it could grow with my daughter. She specializes in automotive performance styled stuff, so she did "bride" fabric to make pads for the harnesses like a true racing harness.

given what you are planning, I have to wonder if contacting the store and seeing if one of their displays aren't being retired soon (they usually just toss them) or hunting C/L as once you have added all of these things it is barely going to be a shell of its original self anyways and you are going to likely be doing some cutting so taking a brand new off the shelf unit might be a little wasteful (just something to think about).

less you consider starting off with something like this......

which would have most of the computer side it figured out for you already.

I have built arduino projects that have incorporated bluetooth in the past, including controlling the arduino from an Android device. It gives you a lot of freedom to react to things if you write the bluetooth interaction flexible enough. For this project the first thing I am adding is a parental shutoff, then more advanced like controlling direction and speed. I am also going to add a joystick calibration mode as from what I understand they can drift over time.

My biggest gap in knowledge is around the wiring of the charger and motor circuits.

We have an old car seat with a 5 point harness that I am going to try to repurpose for the car.

At this point I am leaning towards the power wheels dune razer. I am going to remove the steering column completely. And the existing shift stick location looks like a perfect spot to mount a pillar (don't know if that is the right word) on top of which the joystick would be situated.

The goal of the conversion is to give my daughter the freedom to roam around (mostly) independently as she is unable to walk, that is why I am aiming for an as simple as possible joystick control of the car.

[Suburbancharlie77]

Going the joystick route, you may be able to find some info on the "HEADSTROM" 6 wheeler. It uses chains from the rear driven axles, up to the front wheels. The middle wheels are just dummy wheels, if you will, not driven. But it spins on a dime (may not be quite what you'd want (DIZZY)). The joystick, only operates one motor when pushed to the sides, opposite motor, to the joystick direction. Honestly I'm not sure if it uses a circuit board, but it is an old and obsolete toy, but you may be able to find a schematic??? The tires are like slicks, to allow for the spinning, but if you could figure out a way to eliminate the sit n spin action, grooved tires shouldn't be an issue. Or eliminate the chain, and that should reduce the rotation of the vehicle? I'd imagine that the "4 wheel drive" is mainly for the spin action. But regardless, it's a vehicle like this, using a 4 direction joystick.

Here's an example, I didn't try the phone number.

http://www.rjcooper.com/coopercar/index.html

[flipper]

I have built arduino projects that have incorporated bluetooth in the past, including controlling the arduino from an Android device. It gives you a lot of freedom to react to things if you write the bluetooth interaction flexible enough. For this project the first thing I am adding is a parental shutoff, then more advanced like controlling direction and speed. I am also going to add a joystick calibration mode as from what I understand they can drift over time.

My biggest gap in knowledge is around the wiring of the charger and motor circuits.

We have an old car seat with a 5 point harness that I am going to try to repurpose for the car.

At this point I am leaning towards the power wheels dune razer. I am going to remove the steering column completely. And the existing shift stick location looks like a perfect spot to mount a pillar (don't know if that is the right word) on top of which the joystick would be situated.

The goal of the conversion is to give my daughter the freedom to roam around (mostly) independently as she is unable to walk, that is why I am aiming for an as simple as possible joystick control of the car.

Depending on the motor/charger combo you use. it is just Voltage in Red (+) and Ground ( - ) with whatever connector, and then leads to the motor for the same postive and ground to run when not charging. as far as going in forward or reverse you would need a proper switch (joy stick should do ) and relay to be paired with it




had a little fun reading this trying to find a diagram to display. Intergrating some ideas from battle bots might not actually be the worst idea ever.... maybe without the chain saws
http://members.toast.net/joerger/AskAaron/motors.html


Controlling the front axle to steer is going to require a severo of some sort to rotate the steering linkage to turn the wheels in the desired direction.

Much respect for taking care of your daughter like this and making freedom and ability to get around not only a possibility, but in a more kid friendly way than a wheel chair or other medical device.

PS do you actually write the code for those apps? my brother has been looking for something similar to eliminate the AC controllers for his company's land rovers and integrate all of them into a central tablet for controlling these functions like Tesla and other high end auto makers do.

[texswede]

I have about 20 years experience in software development and have written a wide variety of software (moved around a bit early on). I have not worked on the specifics of electric vehicles before, but have experience with GPS, android, arduino, bluetooth, etc - this will be an interesting challenge to solve.

[texswede]

So I have done some additional research, and have come up with the first draft of wiring diagram.

Motor controller has built in BEC so that will provide power to the arduino as well.

Joystick which has 2 axis, one potentiometer for each axis, will be read by arduino. The arduino will control speed based on Y axis and steering based on X axis.

Speed will be regulated to only change at a specific interval, meaning if joystick goes from at rest (center) position to full forward, it will slowly ramp speed, and vice versa for reverse. If it goes forward to back, the car will come to stop, then start reversing. If the joystick goes back to center and stays still car will break.

The steering will be controlled by linear actuator, the 2 relays will control the direction (which one is active), and the potentiometer will determine position. The joystick X axis potentiometer will be read to determine a target position for the linear actuator, the linear actuator position will then be read to determine if actuator should hold position (both relays open), extend (left open, right closed), retract (right open, left closed).

Depending on how responsive steering is, I may give it some boost by increasing speed on opposite side motor (or decreasing speed on same side).

Based on the wealth of information I have found on this site - this definitely looks doable. Very excited, got sign-off from the boss, and even my daughters PT is onboard

Now I just have to pick a vehicle, need one with good high seats and space to put the linear actuator. The Peg Perego Polaris Rzr 900 looks like a decent choice, but read a recent review they have made it smaller. Also appears steering is all plastic?

I wanted to pickup the vehicle first so I could measure out whether a 2 or 4 inch actuator would be necessary/fit underneath.

Some parts are on the way so I can at least start the joystick logic - driving an imaginary car for now.

[MR_Pat]

Good luck.

[Suburbancharlie77]

Hey Tex, am I right to assume that you're from the southern state, where everything is big?
Perhaps you can share a location with us, and someone like toycrusher may be nearby? If he is, and has a hurricane that you can look at, that may be of great assistance?
The hurricane has metal steering components, as well as a three position, removable 2 person seat. It's just possible that it's also large and flat/square enough to allow her carseat style chair to fit, and allow enough room for a friend or light parent, depending upon the combined total of add on weight that your controls tack on???
That, or an F150 or silverado???
I removed the seat of my silverado, because it's the biggest ride I had, in poor condition, that accommodated my fat butt! I think the seat removed/bed compartment was equal to 36"x 36" of plywood I sit on. That's what I was using as my chase vehicle, until my driver reached 18V, now I use a fake segway to keep up with her, as some of her rides are approaching 10 mph =(

I could be wrong, it may only be 18"x 18"?
I'm thinking I remember 18x18, and I know I only had 2 scraps that I combined to cover the motor/gearbox area.... it's now a windshield and footwell stakebed if you will. The only issue I want you to be aware of with the silverado, if I sit upright too far back as I accelerate, it is a bit of a wheelie machine/back bumper dragger! But simple wheelie bars would be easily installed on anything with the slightest possibility of tipping with a child that strapped/secured, especially raising the center of gravity.

[texswede]

Yeah, I am in Austin. We did take my daughter around today and the hurricane did fit fairly well. If it has a removable seat that would be even better, then I could put a five point harness seat in instead. We have a specialty seat that can be attached to a chair etc that if there was something to attach it to might work.

[Suburbancharlie77]

Well, you'd probably have to reinforce the plastic a bit where you attach to. But yes, the hurricanes that I have, have a 3 position adjustable seat. All total, it may move back about 4"???
But on that model, I don't think there's access to the motors from removing the seat, but I'm not 100% on that. One thing I can assure you of, is that aggressive tread pattern is a bit jostling! My daughters had visibly shakes when driving on pavement. But you may prefer to get something like escalade tires anyway? The hurricane weighs 100 pounds empty, so traction with slicks shouldn't be an issue. One thing about the hurricane, factory it comes with a different battery, that DOES NOT fit the standard 12 volt Power wheels!
Not that it requires a special battery, because it's willing to accept any Fischer Price battery, but the hurricane is the cause (I believe) for the yellow top. It has a higher amp fuse, of 40 amp. Many people love the hurricane. Personally, I was greatly disappointed in mine, early on, and been chin deep in so many other rides, I haven't gotten much chance to look at the hurricane again since. But I was also only using a 30 amp fuse!!! That was a BIG part of my issue.

[Suburbancharlie77]

Well, you'd probably have to reinforce the plastic a bit where you attach to. But yes, the hurricanes that I have, have a 3 position adjustable seat. All total, it may move back about 4"???
But on that model, I don't think there's access to the motors from removing the seat, but I'm not 100% on that. One thing I can assure you of, is that aggressive tread pattern is a bit jostling! My daughters had visibly shakes when driving on pavement. But you may prefer to get something like escalade tires anyway? The hurricane weighs 100 pounds empty, so traction with slicks shouldn't be an issue. One thing about the hurricane, factory it comes with a different battery, that DOES NOT fit the standard 12 volt Power wheels!
Not that it requires a special battery, because it's willing to accept any Fischer Price battery, but the hurricane is the cause (I believe) for the yellow top. It has a higher amp fuse, of 40 amp. Many people love the hurricane. Personally, I was greatly disappointed in mine, early on, and been chin deep in so many other rides, I haven't gotten much chance to look at the hurricane again since. But I was also only using a 30 amp fuse!!! That was a BIG part of my issue.

[Suburbancharlie77]

Well pardner, I'm not from around them there parts.... so I don't know how far Austin is from him, in South Texas, but his knowledge would certainly be worth the drive time! You may want to consider private messaging him to get a better idea as to where/how far he is. He may very well have one to show you??? Look for his name in the master plans section. Toycrusher, with a lightning McQueen with lit up exhaust tailpipes!
Just don't tell him I sent ya

[texswede]

Yeah I took a look around the site to figure out vehicle choices. And drove around some more to different stores to see if I could find them assembled.

The hurricane seems very heavy, 100 lbs.

I think I like the Peg Perego Rzr 900 or Gaucho (both weigh in the 60 lbs range), however I am worried that the Rzr wont have room for the linear actuator. Plus the front axle is plastic:



Rzr axle

However on the gaucho, the axle looks like it is made out of metal:



Gaucho axle

I tried searching around but could not find anyone having done a linear actuator steering mod for the Rzr 900. I don't want to go out and buy a vehicle I can't end up using. If anyone on here has one can you tell me if a 2" firegelli actuator would fit underneath I would very much appreciate it - it is 10" fully extended?



Thanks - and happy labor day weekend everyone!!!

[toycrusher]

I'm afraid I'm 7 hours south of Austin. And I haven't personally done an RC conversion...

As far as vehicles, the rack and pinion steering of the gaucho would likely be a problem. The larger 24v rzr is an awesome platform, I've never gotten my hands on the smaller one. The F150 or Hurricane could work but you will want to replace the wheels. Since your going RC you could get away with rubber wheels

[Suburbancharlie77]

Eh, was just hoping =/

[texswede]

I'm afraid I'm 7 hours south of Austin. And I haven't personally done an RC conversion...

As far as vehicles, the rack and pinion steering of the gaucho would likely be a problem. The larger 24v rzr is an awesome platform, I've never gotten my hands on the smaller one. The F150 or Hurricane could work but you will want to replace the wheels. Since your going RC you could get away with rubber wheels

I guess I will be guinea pig for RC conversion of the gaucho, it was on sale so decided to pull the trigger. I may have to modify the rack and pinion steering, or maybe try a stepper gear motor to drive it. Will try with linear actuator first.

Now for figuring out all the things I need to get, shopping list keeps getting longer. I will setup a test bed so I can work out kinks before I make any modifications to the gaucho itself. I am thinking of just getting a couple of RS-540 motors and mounting some wheels (so I can tell spin velocity/direction) - is that viable without any gears inbetween?

[texswede]

I just picked up a used Gaucho Silver in good working condition I had been checking craigslist but had not found many available locally, and the ones I did see either had already sold, or no response. Then I found one post this morning and picked up this evening (including a spare battery) - I am stoked!!!

peg-perego-silver.jpg (36.35 KiB) Viewed 2011 times

There is a cover for the rack and pinion steering which I will remove to see what space there is for the linear actuator, hopefully it will all fit.

Almost all the other parts have arrived and I have started on the code. May have to take some personal time to work on the project

Will definitely look into pneumatic tires, and putting in actual lights.

[texswede]

So I have to admit at first I was at a loss for how to adapt the rack and pinion steering to the linear actuator, came up with several ideas that had some weak link (at least in my mind). However, internet to the rescue, after extensive searching I found a college project where the used the following on a gaucho:

I am not sure yet how to put the extra arm on the steering, plus of this solution is that I can adjust the center point fairly easily and it does not interfere with the existing steering mechanism.

Out of curiosity where is the existing circuit board located on the Gaucho? I have not taken it apart, but it is not under the hood, and all the wiring leads back toward the rear.

[66deuce]

Those linear actuators are way too slow for RC, don't "freewheel", and don't have a home position.

You need a servo. You can buy really expensive industrial robotic servos, or you can make one with a wiper motor and a standard RC servo:

[texswede]

The one I got moves 2 inches/second, the steering has just over 2 inches in movement when I measured from turning max left to right.

Also actuator has a position potentiometer so I can read the current position and determine whether I need to extend or retract. This allows me to set the position exactly based on the position of the joystick.

I don't have it installed in the car yet but it is hooked up in a test bed so I don't know what the performance will be like for actual driving.

I have parental override by Bluetooth from an Android phone, so it isn't intended as a strict RC.

What do you mean by freewheel?

[hubbardalicia63]

Thank you so much for sharing the information. Our daughter is also suffering from cerebral palsy and my husband was also planning to modify an electric car for her. Cerebral palsy affected her body movement and muscle control and a power wheel electric car will be of great help. We are planning to take her to a physiotherapy treatment in Toronto next week.
My husband has consulted a software professional for the development of such an electric car and he has agreed to develop one very soon.