how to reverse motor without using switch like automation

i want to reverse motor i mean i want o make some kind of project in which i will give give command in ardunio uno ....when some offset come in its way it change its path ..i know it will done with ultrasonic sensor but i want full guideline so plzz help me

snehal3676: i want to reverse motor i mean i want o make some kind of project in which i will give give command in ardunio uno ....when some offset come in its way it change its path ..i know it will done with ultrasonic sensor but i want full guideline so plzz help me

It's a fairly complex project and you don't show any sign of actually having tackled it.

It's quite a common project and I'm sure you will find plenty of examples of solutions other people have created, if you search for them. However, the point of Arduino is that it enables [u]you[/u] to create your own projects, not just to copy other people's work. To finish the project yourself you would need to buy/make the vehicle, choose the sensors you're going to use, choose the type/number of motors for propulsion and steering, work out the voltage and current requirements of the motor(s), find a suitable motor driver circuit, learn how to control the motors in software, learn how to read the sensors in software, write a sketch that uses the sensor inputs to control the motors.