Of course the really easy way is to bang a nail into the centre of the circle and attach a string of length "specific radius". That always works 100%.
...unless you tie the string too tight on the nail, and the string gets a little shorter with every revolution.
One should probably assume at least a tiny bit of intelligence on the part of posters here.
Can you also define specific path if you mean it moves forward for a few meters turns left moves forward again sort of thing it's very different to it following a line or something?
I need it to move in a circle that the user inputs its radius, all I have is 4 dc motor and I cant use any external sensorsI really need help cause I keep changing values of PWM of the motors and I keep getting infinity results I am so confused.