Society of Robots - Robot Forum

General Misc => Misc => Topic started by: pacman411 on January 30, 2013, 08:39:05 AM

Title: My First Robot Project
Post by: pacman411 on January 30, 2013, 08:39:05 AM
Hello All

My Project is a 4 whell drive and 4whell sterring with vision and a gripper I going to be using the pic basic I like to keep the robot no larger then 9 inches X 6 inches X 3 inches for the drive unit.

Right now I I look for some information for a small dc motor with gear box that can attach to the wheel. As for the sterring I am thinking of servo.

Any advice will be welcome

Paul
Title: Re: My First Robot Project
Post by: newInRobotics on January 30, 2013, 09:23:06 AM
Right now I I look for some information for a small dc motor with gear box that can attach to the wheel.
What sort of information are You looking for?

As for the sterring I am thinking of servo.

Any advice will be welcome
My advice is to go for differential steering. To implement What You want (4x4 all wheel steering) You are going to need 3 differential boxes (1 for front, 1 for rear and 1 for propshaft) and 5 universal joints (or 1 universal joint and 4 constant velocity joints). No matter that it will be very difficult to get these parts in robot sizes, but also that will make Your robot chunky, plus it won't be able to turn around its axis making it hard to maneuver. For differential steering You only need four motors.
Title: Re: My First Robot Project
Post by: pacman411 on January 30, 2013, 11:49:45 AM
What I am thinking of is a dc motor with a gearhead attached one each for 4 wheel and a servo to turn the wheel.

Paul
Title: Re: My First Robot Project
Post by: waltr on January 30, 2013, 09:14:56 PM
Did you look at the gear motors from Pololu?
Or did you do a google search on 'gear motors', 'robot gear motors'?

Did you try out the motor calculator found by clicking the 'Robot Tutorials' at the upper right of this screen?
Title: Re: My First Robot Project
Post by: jwatte on January 30, 2013, 09:47:28 PM
I'm using Pololu 37D gear motors, and they've been OK so far -- but I've not really put any real load on them yet.
They also have smaller versions. I've also used their micro-metal gear motors, which are great for small things.
http://www.pololu.com/catalog/category/22 (http://www.pololu.com/catalog/category/22)

For steering, I'd suggest starting with differential drive -- run one side faster than the other. A k a "tank steering." If that's not good enough (that's the mechanism that the Wild Thumper uses, for example,) then you can try building a suspension that can turn the wheel/motor combination. I'm doing that for my rover project, based on the "twin A frame" suspension.
Title: Re: My First Robot Project
Post by: idee17 on March 26, 2013, 08:01:10 PM
I agree with jwatte, but you could use 4 continuos rotation servo, then differential drive would be very easy only using software.