a variable self - compensating detent control system for improved positioning accuracy and repeatability is provided . the detent control system provides a system for reducing positioning errors in the positioning of an x - ray tube in an x - ray imaging system , such as accurate and repeatable positioning of the x - ray tube at detents . the control system preferably includes a sensor unit generating positional or velocity signals indicative of the position or velocity of the x - ray tube and a microprocessor receiving the positional signals and determining an overshoot correction . the overshoot correction is used by the x - ray system to control a locking system controlling the position of the x - ray tube . the sensor unit may employ a potentiometer , a digital encoder , or preferably both in combination to determine the positional or velocity signals .