optical flow sensor for mobile robot navigation

Hi friends..I badly need your help.My project is to design a flow sensor for mobile robot navigation.That is the mobile should not hit the walls on right and left,just go straight.distance is to be measured continuously as velocity of the image and the this data is used to navigate the robot along the straight path.I will be very thankful if anyone guides me on this..Waiting for reply..


do you mean encoder? From what I understood you need two encoders, so you can guide your car in a perfect straight line. if you have some old mouses around the house, there's a sensor and wheel you can use for that. Normally the sensor is quite easy to find in shops, but the encoder wheels aren't for sale. :(