Go Carts and Servos

Interested in Robotics? Here's the place to be.
Diverious
Posts: 10
Joined: Mon May 01, 2006 4:46 pm
Contact:

Post by Diverious » Tue May 02, 2006 11:23 am

It has come to my attention that I would have to weld this together...

I never have welded anything before. What's the best way to go about this? I'm thinking I should find a local community college and see if they wil allow me to work in their shop. That's all I can think of...

Anyone have any suggestions?

Newz2000
Posts: 507
Joined: Wed May 18, 2005 1:01 am
Location: Des Moines, Iowa, USA
Contact:

Post by Newz2000 » Tue May 02, 2006 2:02 pm

My brother and I looked into this.

The tricks that we decided on (but never actually built):
- a geared motor with a rotary encoder or absolute position sensor attached to the gear. That way, for example, if 10 rpms of the motor will turn the kart's wheel 90 degrees the encoder will show a change of 90 degrees, not 10 rpms.

- roboteq makes a very high quality motor controller

- roboteq also has an article about creating a rc/computer controlled car (a regular car, not some model)

- the breaks are a great concern in our opinion and we didn't ever come up with a satisfactory solution. We were concerned that stopping quickly requires a great deal of force on the break pedal. I saw this video of some people who turned an old beat up car into an R/C controlled vehicle. If you watch carefully you'll see how they did the brakes with some hydraulic stuff.

Are you sure you can't buy a kart frame and modify it? Seems much easier than building one yourself, especially since you're not a welder.

My brother and I can both weld, and we have access to a full shop, but I'd still buy one rather than build it if I could. A local place here in Des Moines had a rough looking kart with a working gas engine and a solid frame for $200. That's pretty good if you consider the cost of the raw materials. And you don't have to flip your kart over to see if the roll bars are strong enough.

I did some research, and most of the relevant info was found in the context of building heavy weight class combat bots, the number one recomendation was to buy a high quality motor controller. Of course I'd rather build one, but I also know when to take advise.

Diverious
Posts: 10
Joined: Mon May 01, 2006 4:46 pm
Contact:

Post by Diverious » Tue May 02, 2006 2:13 pm

The Go Kart I want to make will eventually have sensors and a lcd screen, so I think I will have to weld eventually anyway.

Also I want to eventually to tell the Go Kart to go this speed (Sa) for this long (Ta) and the steering wheel turned at this degree(Da), then go at this speed (Sb)... etc... I figured that to make the Kart go at a specific speed it had to be an eletric motor, most Go Karts have gas motors.. This is all assumption, I may be wrong.

The Go Kart has to be manually drivable. I'm concerned that if the steering shaft is attached to a motor without or without a gear it will be hard to steer manually, again an assumption.

If I can go with a gas car and have the same outcome, then could someone tell me that this will work?

One way is to hook the steering wheel up to a potentiometer or opto disk and havign it control the motor that way instead. Which seems like I need to weld. But if the better way is to hook up tyhe steering wheel directly to the steering shaft which hooks up to the motor, then could someone please tell me?

I honestly don't know much about this stuff, so if I know what is needed I can do more research and come up with a good schematic.

Thanks a lot guys

User avatar
Chris Smith
Posts: 4325
Joined: Tue Dec 04, 2001 1:01 am
Location: Bieber Ca.

Post by Chris Smith » Tue May 02, 2006 3:01 pm

Sounds like the next solar flare will put you into the wall?

Why reinvent the wheel?

A manual driven pitman arm setup will suffice, and its not even complex.

A couple of heim joints, rods, and three levers.

And it doesn’t even weigh a whole lot either?

Your power requirements to drive your set up alone, will make you come in last place every time.

tommyfilth
Posts: 1
Joined: Sat May 06, 2006 8:43 pm
Contact:

Post by tommyfilth » Sat May 06, 2006 9:03 pm

I would like to interject with a suggestion and a question, I'm trying to create a high power servo using a windshield wiper motor. This might be of use to you as the motor is capable of 2500 in/oz of torque, compared to the 160 or so with a regular R/C servo. I finally found some information here.
http://homepages.which.net/~paul.hills/ ... Servo.html
Now, I'm a little new to electronics so I'm unsure of how many parts of the "circuit building blocks" I would need to use to build a servo to connect to a R/C reciever. If this is an avenue you might be willing to look into I would share any information I come across, also if anybody else can push me in the right direction, I would appreciate it.

Tommy

P.S. the circuits link on the bottom has a bunch more information.

User avatar
Sambuchi
Posts: 366
Joined: Tue Jan 18, 2005 1:01 am
Location: Orlando FL
Contact:

Post by Sambuchi » Thu May 11, 2006 4:20 pm

Hello Diverious

I am not sure if you have seen this or not... The video below is the Stanford University's robot: "Stanley"... The won the "Grand Challenge Last year"

I have been researching how they were able to do this with little luck.. I will share my information when I find something.


I hope this video will give hope and not frustration :grin:

http://www.pbs.org/wgbh/nova/darpa/medi ... 00-10.html

Good Luck

User avatar
compwiz575
Posts: 44
Joined: Fri Jun 09, 2006 12:34 pm
Contact:

Post by compwiz575 » Thu Jun 15, 2006 6:09 pm

whouldn't a geared up stepper or brushless motor do the trick?

RyanMBruce
Posts: 3
Joined: Fri Jul 14, 2006 11:21 am
Location: Ames/Des Moines
Contact:

Some resources

Post by RyanMBruce » Fri Jul 14, 2006 11:32 am

Hey there,

I'm with the Iowa State University Robotics Club, and we have a project similar to what you are talking about. The project name is the Autonomous Robotic Kart (ARK), and we have a page for it on our wiki here:

http://nukelab1.student.iastate.edu/w

We just finished welding the mounts in place, and attaching all of the servos, now we're working on the electronics box so that we can control the servos and read the sensor information. The overall goal is to build an autonomous kart that is much more affordable than its Stanley-sized counterparts.

Since Stanley was mentioned earlier, I thought I would put out a link to an informative paper they wrote after winning the DARPA Grand Challenge. You can find the paper here:

http://robots.stanford.edu/papers/thrun.stanley05.html

User avatar
Sambuchi
Posts: 366
Joined: Tue Jan 18, 2005 1:01 am
Location: Orlando FL
Contact:

Post by Sambuchi » Sat Jul 15, 2006 9:35 am

hello RyanMBruce

wow.. what a great project.. there a lot on your page that i find interesting..

the SICK LMS 200. looks like a great tool. how much did you spend for one. i am amazed how well it works.

RyanMBruce
Posts: 3
Joined: Fri Jul 14, 2006 11:21 am
Location: Ames/Des Moines
Contact:

Post by RyanMBruce » Mon Jul 17, 2006 9:47 am

Well, we paid about US$4,500 for it, but they retail for quite a bit more. You can check them out at Sick's website here:

http://www.sick.com

It does work amazingly well, and it is a very powerful tool. I have yet to learn all of the details of its operation, but I have been able to create 3D images with it, and I am working on making a pan-tilt or 360 degree scanning base for it so that I can mount it on the ark and create 3D images on the fly, and texture them using video from a camera. I have a lot of information that I still have to put up on the wiki, but check back often, as I should be updating it soon.

-Ryan

ProboticsAmerica
Posts: 8
Joined: Thu May 19, 2005 1:01 am
Contact:

RC & Driver control

Post by ProboticsAmerica » Tue Nov 07, 2006 5:09 pm

Have the driver operated steering wheel and shaft attached solidly to the other steering components. Use a slipping connection between the motor and the shaft or a slipping connection between the drivers steering system and the motor. When I say 'slipping connection' I mean a connection that connects to the steering system solidly enough to turn the wheels, but loose enough that the driver can overpower it and drive normally. When the motor turns the motor will steer the car unless 1) the driver overrides or 2) the wheels are physically forced to turn and override the slipping connection.

The best part of it is that the driver always has control - if he doesn't like what the motor is doing he just steers the other way.

_____________________________________________
Robots for safety education and entertainment
www.proboticsamerica.com

User avatar
Sambuchi
Posts: 366
Joined: Tue Jan 18, 2005 1:01 am
Location: Orlando FL
Contact:

Post by Sambuchi » Wed Nov 15, 2006 5:06 am

have you done this before ProboticsAmerica ?

You make it sound easy!?

Could you buy a kit...

Buzz
Posts: 3
Joined: Thu Dec 07, 2006 2:48 pm
Location: Lockhart, Texas
Contact:

Post by Buzz » Fri Dec 08, 2006 8:52 am

I would love to offer some thoughts on the physical fabrication of your project. I have worked building go karts.

This project intrigues me to no end... where are you at presently in your endeavors?


The Japanese have been working on this project for many years. They want to build a car with "auto-pilot" at the wheel.

Their project is more complex though, since they have no one to monitor direction. Since you will have the RC controller in your hands, you will be the direction for this kart.


A lot can be gained from gleaning the Japanese project.
As For Me and My House, We Shall Serve The Lord.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest