A device and method for loading pellets into chemical reactor tubes. The tube component is sleeved on the leg unit, and is formed with positioning holes aligned along a tube axis. After correcting the estimated current vehicle position based on the current vehicle position from the GPS receiver, a power supply to the GPS receiver is turned off, and thereafter an error of the estimated current vehicle position is calculated based on an error accumulated for a certain time period regarding the speed and the direction. A memory device is capable of storing rendering information, wherein the memory device is accessible in response to the generate_event command.