i made a line following robot ,used pid control algorithm ,tuned it properly for a black line with white background,it worked properly,but when i changed it to white line over black background ,it follows the line but moves in a zig zag manner,both the tracks r the same with the same track width.
the only thing i changed was from this
unsigned int pos = qtra.readLine(sensors);
unsigned int pos = qtra.readLine(sensors,QTR_EMITTERS_ON,1 );
please help ...urgent..have competition day after