I have created a self balancing robot. It uses PID control to control its pitch angle and gets the feedback from gyroscope and accelerometer. But I have not used any sensor to feedback the displacement to the controller. I have just approximated the voltage applying to the motor to the displacement through programming (let suppose 5v to the motor will make the motor to rotate for 1 rev/s and after integrating it , it will give the displacement covered). Through which I was able to maintain the robot at a single position. But now its time write the report and I do not know what to call this type of feedback of displacement. Thanks
I would call this dead reckoning, because you do not have any actual measurement of the position, but are just calculating it based on the estimated speed of the motor.