This invention concerns robotic systems and is specifically concerned with an improved apparatus and method for remotely positioning a sensor, such as an ultrasonic probe, in limited access areas within a nuclear reactor. The apparatus includes a bottom frame and a top cover which is substantially aligned with and positioned above the bottom frame. A sensor is connected to the top cover and linear rails are connected to the bottom frame in a parallel relationship. There is a mechanism movably connected to the first and second linear rails in order to allow horizontal travel of the top cover. Further, there is at least one cable connected to the sensor and a power source, signal source or receiver.