Go Carts and Servos

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Diverious
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Go Carts and Servos

Post by Diverious » Mon May 01, 2006 4:51 pm

Hi,

I want to make a go cart from scratch, however, I want it to be both an RC go kart and a drivable go kart. I need to program its steering in exact angle degrees of the wheels, and exact speeds that I would like it to run.

I'm thinking that I need servos to acheive this preciseness in the speed in steering.

Can someone recommend the servos needed to work with wheels as big as a go kart, and won't break?

Please help, I can't find help anywhere on the internet.

Thanks!

JPKNHTP
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Post by JPKNHTP » Mon May 01, 2006 5:43 pm

-JPKNHTP
-God Bless

Diverious
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Post by Diverious » Mon May 01, 2006 6:07 pm

I have a Computer Engineering degree at MSU so I know very very little about this stuff, but I can learn, I'm a programmer at heart. I honestly don't know what is needed I just know I need precision. Could you give me model, manufacture, examples of what to use to acheive this?

JPKNHTP
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Post by JPKNHTP » Mon May 01, 2006 8:24 pm

-JPKNHTP
-God Bless

Diverious
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Post by Diverious » Mon May 01, 2006 8:55 pm

Thanks a lot for your time!

Your saying that I need a geared motor attached to a steering shaft that will move when forced by the driver but can also move when controled by RC. I'm guessing this geared motor will move the steering shaft. I'm also guessing that a rotary encoder will be attached to this geared motor? Or will the rotary encoder will be attached to the motors controling the speed?

I sort of understand, but I know for a fact that there are so many types of geared motors, rotary encoders, steering shafts out there with different types of torque, made out of different types of metal, different abilities of preciseness, better quality depending on the manufacture.

I know the significance of each one of these details, and I know their definitions, but I still don't know what I need. I don't know how much torque I need, or what manufacture.

This is what I do know. I'm thinking at it can max out at 40 mph, and maybe thats too high and should max out at 30mph in speed. The whole go kart needs to fit an adult.

I'm not using this an a performance racing go kart or even recreation. It's merely part of a bigger project.

So this go kart can be really basic, the frame is just a rectangle with a seat, steering wheel (im guessing is attached to the steering shaft). Two wheels in the front, and 2 wheels in the back, and big enough to fit an adult. So im thinking including the batteries to power it it needs to support 200 to 250 pounds, I'm only 160 so I'm just guessing.

From a computer I want to control the exact degree in angle of the steering. Also I want to control the exact speed. I want to plug in a mph number and it will match it accordingly remotely.

You have help me a lot so far, any further assistance will be wonderful, thank you so much!!

Diverious
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Post by Diverious » Mon May 01, 2006 9:33 pm

I'm using this website as a guide for right now...

http://www.diygokarts.com/kart-plans/ka ... -main.html

Unless I find a better guide

dyarker
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Post by dyarker » Mon May 01, 2006 9:38 pm

Ah, information! Now it looks like at least two motors. One move the kart, and one one to control direction on the steering wheel shaft. Also a servo or solenoid for the brakes. Hall effect sensor on rear axle should be good enough for speed and distance. Probably and optical encoded disk on steering wheel shaft in a PID feedback loop.
Dale Y

Diverious
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Post by Diverious » Mon May 01, 2006 10:02 pm

I was looking at some patent sites:
http://www.freepatentsonline.com/6900564.html

and it was talking about a worm shaft and a worm wheel that connects the eletric motor to the steering shaft. I don't know if I understood it completely.

I found this steering shaft:
http://www.northerntool.com/webapp/wcs/ ... oreId=6970

How would I connect this to an eletric gearing motor?

dyarker
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Post by dyarker » Mon May 01, 2006 10:17 pm

Another thought. Instead of rigging the the steering motor to be overpowered by a person turning the steering wheel, drive by wire. That is the motor always controls direction. The driver on-board either uses a joystick or a steering wheel only connected to a potentiometer or another optical coded disk.

For safety, when driver is in kart the RC circuits are positively locked out. (You don't want to be like Batman controlled by Penquin by some clown with a radio transmiter.) And in RC mode, a loss of signal triggers a complete stop.

Where are you putting all the batteries?
Dale Y

JPKNHTP
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Post by JPKNHTP » Mon May 01, 2006 10:19 pm

-JPKNHTP
-God Bless

Diverious
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Post by Diverious » Mon May 01, 2006 10:25 pm

I have to have a normal steering wheel, can't use a joystick for the driver. I'm guessing the batteries would be behind the seat of the driver.

I know that I need a geared motor, and I need to figure out its torque required, but how to I attach the motor to the steering shaft? Also what type of motor does it need to be so that when the driver uses the steering wheel it allows the driver to do so?

JPKNHTP
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Post by JPKNHTP » Mon May 01, 2006 10:30 pm

-JPKNHTP
-God Bless

Diverious
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Post by Diverious » Mon May 01, 2006 10:38 pm

I want to be able to go from automatic steering to manual steering without changing anything physically. Won't this be possible? Maybe the gear is moved out of the way, and when the RC is activated it moves into place?

Do you have an example of the gear, geared motor, and rotary encorder?

dyarker
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Post by dyarker » Tue May 02, 2006 6:04 am

"I want to be able to go from automatic steering to manual steering without changing anything physically." Okay, no joystick. That's why I also suggested a steering wheel with a potentiometer or opto disk. Think of it as power steering. No geared motor to force or gears to move to disconnect.
Dale Y

Diverious
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Post by Diverious » Tue May 02, 2006 8:52 am

Hmm, that's a good idea too, what will give the steering wheel the strong resistance a normal car gives?

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