GradeStar 3D machine-control systems can be based either on GPS technology (GradeStar 3D GPS) or robotic-total-station technology (GradeStar TPS, for Terrestrial Positioning System). In the latter system, the total station communicates via radio modem with the computer on the machine and measures the exact 3D position of a prism target on the machine. Combined with the measured values of tilt sensors on a motor grader, the position and heading of the grader is continuously determined.
