# Electric Buggy Project



## Woodsmith (Jun 5, 2008)

That's a nice buggy and looks fun too. I can see why you would want it to go electric, the ICE was a bit noisy!

Is it skid steer? It looked that way on the video.
It has the same speed range as my EV tractor project though at 72v may be much more lively!


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## JRP3 (Mar 7, 2008)

Glad to see you're making progress on this. You should talk to Carl at EVdrives.com, he has the diodes, resistors, and contactors for your Alltrax if you need them. Pre-wired and ready to go.


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## JRP3 (Mar 7, 2008)

Depending on your 12 volt power needs you could just run from a 12 volt battery that you recharge when you charge the pack. Or get a DC/DC, I just picked up a Chennic for $99 including shipping which seems to be working pretty well. PM Sharon here in the forums if you're interested.


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## Tinodesis (May 4, 2008)

Woodsmith said:


> That's a nice buggy and looks fun too. I can see why you would want it to go electric, the ICE was a bit noisy!
> 
> Is it skid steer? It looked that way on the video.
> It has the same speed range as my EV tractor project though at 72v may be much more lively!


Hi Woody,

It is skid-steer in the video. I extended the frame and moved the rear wheels back to allow for rear-steer. It should be a much smoother ride. The batteries will be mounted between the rear wheels over the tie rod and actuator.



JRP3 said:


> Glad to see you're making progress on this. You should talk to Carl at EVdrives.com, he has the diodes, resistors, and contactors for your Alltrax if you need them. Pre-wired and ready to go.


Hi JRP3,

Thanks for the contact info. I'm having friends build this for me and want to get the components ready for them.

I spent a lot of time last summer trying to go electric with my Argo 8x8. I decided to just keep the two-stroke in it for now and I'm glad I did. It's running and I can see how much power it takes to turn a skid-steer. The buggy is a much better vehicle for my needs.

I'm waiting to find out how much 12V current I'll need before ordering a DC/DC.


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## Woodsmith (Jun 5, 2008)

I have been racking my (aging) brain cells as to what your buggy reminded me of. The little four wheel ATV buggies in the 1970's sci fi film Silent Running.
Here, at 3.10mins on YouTube.


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## Tinodesis (May 4, 2008)

Those are some cool buggies, Woody.

What do you guys think of my rear-steer design?

The original plan had VW axle assemblies attached by a solid axle across the back. My design didn't work and a guy suggested going front wheel drive. That's what I plan to do now.

The steering levers and tie rod in the pictures are not welded up yet. A linear actuator will move the tie rod back and forth. The rear wheels will only turn about 20 degrees each way. The steel is 3/8" plate. Any suggestions?


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## Woodsmith (Jun 5, 2008)

You will need to adjust the angle of your kingpin.

Firstly, castor. The kingpin should point ahead of the wheel to ground contact point so that there is a little castoring action. That will stop the wheels from 'shimmying' and help you keep a steady straight line when you want to.

Secondly, kingpin inclination (KPI). The kingpin should also point outwards so that it is pointing at the contact patch of the tyre to the ground. This will reduce the effect of the tyre pulling on the steering when it hits a bump. You will want the KPI to be a little inboard of the centre line of the tyre so that there is some 'feel' to the steering though I don't know if you will have any feedback through your joystick.

There are other things like wheel camber, the wheel leaning in or out at the top, but you probably won't need to worry about that too much.

Steering is something that needs to be right as that will determine whether your buggy is fun to drive or a real pain with bad handling and possibly dangerous. If you have a look at my tractor thread you will see that even on a slow speed tractor I have had to get the steering geometry right to make it safe and nice.


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## Woodsmith (Jun 5, 2008)

I notice on your photo that there is a double sproket on the original rear drive axle.

Can you turn the axle around so that it protrudes into the inside of the chassis? 
You can then add a sproket to it to drive a sproket inboard of the steering hub. The drive shaft can then have a U joint in the hub to allow you to have 4x4 again.

The inner half of the drive shaft can be mounted between two pillow block bearings with the driven sprocket inbetween. That will then give you a fully supported shaft that can have the U joint mounted onto it in the hub.

To support the wheel you will need a hollow stub axle tube with the drive shaft running inside it on bearings or bushes. It will drive your wheel from the outer face.

Alternatively, the outer drive shaft can be mounted in a double taper roller bearing (look for front wheel drive car front wheel bearings like the ones I use for my front axle pivot on the tractor) set in the steering hub and the the wheel can be mounted straight onto the drive shaft.


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## Tinodesis (May 4, 2008)

Thank you for the detailed reply, Woody.

I have been struggling with steering and suspension set ups and your thread cleared up a lot for me.

I have some homework to do now. The buggy may roll before I get the changes made, but I will follow through until it's done right.

Regards and thanks again!


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## Tinodesis (May 4, 2008)

I'm still making progress on my buggy. After becoming more familiar with the suspension geometry I decided to use parts from a 2006 Yamaha Rhino. I bought used parts on ebay and some new ones from a local ATV shop.

My chassis is 15" wider than a Rhino, so I'm not sure my steering levers are setup correctly. Instead of using a rack and pinion I want to use tubing, or a bar, which will then be moved side to side by a linear actuator.

I have some updated photos and a 2D CAD drawing of my buggy from the rear. The 2D pic is missing hidden lines, but I just wanted to show what I have planned for steering. The blue box is where the batteries will be mounted. The frame extension will be braced and attached to the original frame of the buggy.

Advice is welcome!


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## toddshotrods (Feb 10, 2009)

I'm not familiar with ATVs but on cars the inner tie rod pivot points must be at the same width from center as the control arm pivot points (we normally use the lower control arm pivot points on the stuff I'm used to). Having the tie rods and the control arms following different arcs results in bumpsteer. In your case, it look like your wheels will toe-in on bump - rear steer on the rear wheels right?

As I said, I am not used to off-road stuff, so if this doesn't apply just ignore me.


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## Tinodesis (May 4, 2008)

toddshotrods said:


> I'm not familiar with ATVs but on cars the inner tie rod pivot points must be at the same width from center as the control arm pivot points (we normally use the lower control arm pivot points on the stuff I'm used to). Having the tie rods and the control arms following different arcs results in bumpsteer. In your case, it look like your wheels will toe-in on bump - rear steer on the rear wheels right?
> 
> As I said, I am not used to off-road stuff, so if this doesn't apply just ignore me.


Hi Todd,

You're correct about the bumpsteer. I was expecting it. I'm not going to feel it at the joystick, but I don't want it destroying parts regardless. I was trying to go over my batteries in the pic above. I've seen spindles with dropped steering arms but they were for cars.

Yes, rear-steer on the rear wheels. The latest version of this buggy is rear-steer instead of skid-steer and the ride looks much smoother.

Does this pic look better to you? Note the spindles aren't shown in this drawing, but everything is drawn as accurately as possible.


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## toddshotrods (Feb 10, 2009)

Tinodesis said:


> ...You're correct about the bumpsteer. I was expecting it. I'm not going to feel it at the joystick, but I don't want it destroying parts regardless...


That would actually have been worse, because you wouldn't have a direct "feel" for what's going on with the wheels (behind you). You would have been reacting to what the bumpsteer had already caused the vehicle to do. 



Tinodesis said:


> ...I was trying to go over my batteries in the pic above...
> 
> ...Does this pic look better to you? Note the spindles aren't shown in this drawing, but everything is drawn as accurately as possible...


Much better!  Can you split the pack over and under the steering linkage?


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## Tinodesis (May 4, 2008)

toddshotrods said:


> That would actually have been worse, because you wouldn't have a direct "feel" for what's going on with the wheels (behind you). You would have been reacting to what the bumpsteer had already caused the vehicle to do.
> 
> 
> Much better!  Can you split the pack over and under the steering linkage?


Thanks for the correction. The ICE buggy and Rhino forums weren't giving me any answers. Many people there don't have any interest in going electric so they don't even respond.

I will now work on locating the batteries around the steering components. I had not considered splitting them over and under, but I'll see what fits.

Thanks again!


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## Tinodesis (May 4, 2008)

*Progress Pictures*

Here are some recent pictures of the buggy.

The battery box will slide in from the rear.

The contactor is connected using .25" x .75" copper bar and 2/0 wire.

The tie rod will be behind the battery box.


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## Tinodesis (May 4, 2008)

*Solo Test Ride Video!*

I went first my first solo ride yesterday. It performs beyond my expectations! Top speed is quicker than I expected so I'm going to adjust the controller to slow it down. I will post more video when I have it.

Enjoy the video. http://www.youtube.com/watch?v=YZorqCz7eGo

Tino


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## toddshotrods (Feb 10, 2009)

That's awesome! Congrats on your first ride!


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## JRP3 (Mar 7, 2008)

Great work, glad to see you get it running.


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## Tinodesis (May 4, 2008)

toddshotrods said:


> That's awesome! Congrats on your first ride!


Thanks, Todd. It was a little touchy at first.



JRP3 said:


> Great work, glad to see you get it running.


Hi JRP3. I have been at this since before you got your AMPhibian going. I was inspired by that project.

The video is pretty tame, but the buggy really cruises well at about 10 MPH. The rear-steer works well even though it's a bit noisy.


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## Anaerin (Feb 4, 2009)

I agree, this is a fantastic comments. Could I make a few suggestions, however.

Rear-wheel steering is fantastic for low-speed maneuverability, but at high speeds it can be extremely "Twitchy". May I suggest some kind of speed-related ramping down, so when operating at speed it turns the wheels a lot less than when stationary/crawling?

To make driving this a LOT easier, I'd also recommend the steering be set up to auto-centre. It looks like, at the moment, moving the stick moves the wheels like a switch. Press left and the wheels turn left, and keep turning for as long as you hold the stick that way. Release, and they stop turning, but nothing else. This means that as it is, especially with the wheels well behind the driver's field of view, he has no idea where they are pointed until he moves forward, which is inconvenient at best, and dangerous at worst. If the control stick is always reflecting the current state of the wheels (centered and untouched, the wheels are centered and pointing straight, pushed to one side, pointing to that side) it's immediately apparent which way the vehicle will move. I don't believe it would be that difficult to manage, most radio-controlled cars manage it fairly easily.

Other than these minor niggles, I think this is a fantastic little buggy.


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## Tinodesis (May 4, 2008)

Anaerin said:


> I agree, this is a fantastic comments. Could I make a few suggestions, however.
> 
> Rear-wheel steering is fantastic for low-speed maneuverability, but at high speeds it can be extremely "Twitchy". May I suggest some kind of speed-related ramping down, so when operating at speed it turns the wheels a lot less than when stationary/crawling?
> 
> ...


Hello Anaerin,

You described my steering well and I agree with your suggestions. Finding a joystick and an auto-center actuator has been the most frustrating part of the project. The hobby actuators are too small and the industrial ones are too expensive. I would pay more for an industrial one if I could find a company willing to sell one to me.

As it is, the buggy is capable of speeds that are unsafe for the switch on/off method I'm using. I don't plan to drive faster than 10 MPH anyway. That's why I'll be using the half-throttle option of my Alltrax controller.

If anyone can point me to an actuator with a three inch stroke and speed control I would appreciate it. For now Ill be sticking to lower speeds where I'm comfortable and the buggy is stable. It's still a lot of fun!


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## Anaerin (Feb 4, 2009)

Tinodesis said:


> You described my steering well and I agree with your suggestions. Finding a joystick and an auto-center actuator has been the most frustrating part of the project. The hobby actuators are too small and the industrial ones are too expensive. I would pay more for an industrial one if I could find a company willing to sell one to me.


How about $3 at your local goodwill? That's how much you'll end up paying for a PC Analog joystick (One of the older ones, that uses the "Joystick" interface, and is therefore just a pair of variable resistors)
http://webcache.googleusercontent.c...ck/+interface+analog+joystick+microcontroller
This is how to interface an analog joystick to a microcontroller (A basic stamp, in this case, but the same technique applies to an Arduino or PIC). (Google Cache link, as the original site seems broken). And if you're using a microcontroller anyway, you can use a heavy-duty servo to turn the back wheels, which will then give you the feedback necessary to position the rear wheels exactly.


Tinodesis said:


> If anyone can point me to an actuator with a three inch stroke and speed control I would appreciate it. For now Ill be sticking to lower speeds where I'm comfortable and the buggy is stable. It's still a lot of fun!


Here's a Linear actuator with a 4" stroke, and a potentiometer for position feedback: http://progressiveautomations.com/l...ter-stroke-size-4-force-200-lbs-/prod_75.html


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## Tinodesis (May 4, 2008)

Anaerin said:


> How about $3 at your local goodwill? That's how much you'll end up paying for a PC Analog joystick (One of the older ones, that uses the "Joystick" interface, and is therefore just a pair of variable resistors)
> http://webcache.googleusercontent.c...ck/+interface+analog+joystick+microcontroller
> This is how to interface an analog joystick to a microcontroller (A basic stamp, in this case, but the same technique applies to an Arduino or PIC). (Google Cache link, as the original site seems broken). And if you're using a microcontroller anyway, you can use a heavy-duty servo to turn the back wheels, which will then give you the feedback necessary to position the rear wheels exactly.
> 
> Here's a Linear actuator with a 4" stroke, and a potentiometer for position feedback: http://progressiveautomations.com/l...ter-stroke-size-4-force-200-lbs-/prod_75.html


Thanks for the information. I'll see if I can find a suitable joystick.

What are your thoughts on this actuator? http://servocity.com/html/1010_lbs__thrust_linear_actuat.html 

I would prefer one with more than enough power. If I use one too small, I don't think it will last long. I'm not sure how to estimate how much force I need because it will vary with terrain, surface material, etc.


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## toddshotrods (Feb 10, 2009)

Wouldn't you need a stepper motor, that is controlled according to "position", to have a setup that returns to center automatically? There has to be some reliable way of accurately and consistently locating the exact center position every time you allow the joystick to return to its center position. I'm familiar with stepper motors from CNC machining. They allow huge machines to move to an exact coordinate very quickly, and with incredible accuracy.


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## Anaerin (Feb 4, 2009)

toddshotrods said:


> Wouldn't you need a stepper motor, that is controlled according to "position", to have a setup that returns to center automatically? There has to be some reliable way of accurately and consistently locating the exact center position every time you allow the joystick to return to its center position. I'm familiar with stepper motors from CNC machining. They allow huge machines to move to an exact coordinate very quickly, and with incredible accuracy.


A stepper or server motor would be best for this, but you could use a motor with pot as well. The coding is simpler, too. Something like: IF Stick_Position > Motor_Position THEN Motor++ ELSEIF Stick_Position < Motor_Position THEN Motor-- ENDIF. Then the position of the stick always relates directly to the position of the wheels (Within the capabilities of the motor), and the auto-centering of the stick handles centering the wheels.

As for the actuator shown, that looks like it would certainly do the job.


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## Sunking (Aug 10, 2009)

I have been watching this thread with some interest for a while as I have converted a couple of golf carts which are about the same size and weight as your buggy. But l am curious what the purpose of your buggy is?

The reason I ask is the performance of you OP is really slow especially for the voltage and motor you are using. I know a lot of folks that convert golf carts to do all sorts of things from racing to hauling firewood and farm chores to off-roading fun and games.

I use a 48 volt DC motor with an Alltrax 4865 controller. I get 30 MPH at 5200 RPM and enough torque to raise the front wheels off the ground and bark the tires. It reaches 30 MPH in just a few feet. Well that may be exaggerating a bit, but it reaches top speed extremely quick.

Have you considered using a golf cart frame? You frame looks extremely heavy.


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## Tinodesis (May 4, 2008)

Sunking said:


> I have been watching this thread with some interest for a while as I have converted a couple of golf carts which are about the same size and weight as your buggy. But l am curious what the purpose of your buggy is?


Hello Sunking.
The intended purpose of the buggy is to give me an off-road vehicle I can drive while staying in my electric wheelchair. I like to hunt and I've never been able to get far from the van or the road. I can use the buggy on jeep trails and logging roads or mild terrain for that reason. Another important purpose is just to have fun. It's all about having fun for me.


> The reason I ask is the performance of you OP is really slow especially for the voltage and motor you are using. I know a lot of folks that convert golf carts to do all sorts of things from racing to hauling firewood and farm chores to off-roading fun and games.


I need to revise those numbers. Actual performance is at least double what I posted. The gear ratio of my transmission is 24:1 (not 48:1) so that was an error on my part.


> I use a 48 volt DC motor with an Alltrax 4865 controller. I get 30 MPH at 5200 RPM and enough torque to raise the front wheels off the ground and bark the tires. It reaches 30 MPH in just a few feet. Well that may be exaggerating a bit, but it reaches top speed extremely quick.


I don't think your exaggerating much. My buggy gets up to 20 MPH really quick, too. Able-bodied friends helping me with the build have gone much faster than I did in the video, and even with the aggressive tread on my tires, it will spin out in a heart beat.


> Have you considered using a golf cart frame? You frame looks extremely heavy.


I haven't looked at golf cart frames, but I will. My buggy is built like a tank and that's why I went with a 72 Volt system. I realize now that a 48 Volt system would have been a better match (lower speed, still lots of torque), but I'm still very happy with it.

The video I posted doesn't really show the buggy in a favorable way. I wasn't dressed for the cold, the wind was howling, and the sun was behind me. I need practice driving it and some good weather to really see what I can do in it. 

This project has been a great learning experience for me. I've learned a few lessons the hard way and still look forward finding a better design in the future.


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## Sunking (Aug 10, 2009)

Tinodesis said:


> My buggy is built like a tank and that's why I went with a 72 Volt system. I realize now that a 48 Volt system would have been a better match (lower speed, still lots of torque), but I'm still very happy with it.


 As long as you are happy with it. I was just wondering what you did with it because it looks very heavy. That is why I mentioned a golf cart frame as they are light, have a suspension, and parts are available every where. Lots of places sell various 48 volt motors made for wither torque, or speed.

I do now a few guys who use 60 and 72 volts in their converted golf cart buggies, but those are made for racing and reach speeds up to 60 to 70 MPH which is NUTZ IMO.

Good luck and be careful


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