Help needed to construct my First Robot

[rahavoc]

Hello  Everyone!
I am using 4 wheel,2 motor(300rpm) drive platform.
I want to steer the front wheels using differential drive or castor wheel
Can any one please tell  what is the mechanism required and how to implement the two methods.
also suggest me which method  has to put for the robo platform.

[artbyrobot1]

A great tutorial for basic first time robot it is very thorough

http://letsmakerobots.com/start

[rahavoc]

Hi
Thanks for the tutorial.
Can you tell me how to implement Ackerman steering to my front wheels.
What equipment I need for the wheels to steer using a servo motor.

[cyberjeff]

Hi
Thanks for the tutorial.
Can you tell me how to implement Ackerman steering to my front wheels.
What equipment I need for the wheels to steer using a servo motor.

Ackerman steering appears to be rare in robots. What I suggest you do is look at RC cars where this type of steering is common, and  of course steered by a servo.

I have no interest in RC cars or for that matter wheeled robots but I have a friend who ran RC cars for a while and there is a huge selection of parts for steering gear, it's rather involved. You should be able to adjust your geometry for the length of the vehicle.

Most 4 wheeled robots need some kind of slip to turn sharply with the attention being concentrated on what a robot does and not so much on whether it has efficient steering.

[rahavoc]

I have a TowerPro SG 90 Micro Servo Motor.
Can you please tell how to rotate it using PWM method,I am using Atmega 16.

[cyberjeff]

I have a TowerPro SG 90 Micro Servo Motor.
Can you please tell how to rotate it using PWM method,I am using Atmega 16.

Assuming you mean software:

I can't tell you that.

I'll tell you what I would do. I'd get an Arduino Uno and load up the Arduino IDE:

https://www.arduino.cc/en/main/software

They have sample code in there for servos

Arduinos and their clones are widely available. There is a vast assortment of electronics that bolts right on, the IDE already has the libraries for most devices you need, otherwise they are easy to come by. You won't need any special hardware to program it, just a USB cable and that will come with the Arduino.

I find it pretty easy to set up. And then you can get to the hard parts of making it do what you want.

YMMV

[rahavoc]

I am using Atmega 16 micro controller,Tell me how to write a programme in PWM mode using timer0.

[cyberjeff]

I am using Atmega 16 micro controller,Tell me how to write a programme in PWM mode using timer0.

Google is your friend in all these things:

https://www.newbiehack.com/MicrocontrollerControlAHobbyServo.aspx

Among many others.

All this is too far down in the weeds to hold my interest.

[ProgressiveAutomations]

Steering via the front wheels like a regular car (which is what I think you mean by differential drive) is a complex mechanical task.  The electronics of it is easy, it's just a servo that turns back and forth, but the mechanics needed to actually turn the wheels the way you want them is hard.

If you're talking about differential drive, like spinning the right wheel forwards and the left wheel backwards to turn left, that is really easy to program and make.  With 4 wheels its a bit more difficult, and you won't get as smooth control as you would with 2 wheels and a castor wheel.

Using a castor wheel with 4 wheels doesn't make sense to me... What did you have in mind for the wheel base?