In warehousing logistics, most regions still use manual sorting with low efficiency and high cost. Especially in some special work areas, such as high temperatures, severe electronic radiation, urgent need for small robots to replace manual labor. This design uses PID control algorithm to independently determine the weight of the goods, wait for receiving goods at a designated location, move forward at a constant speed, and transport its weight to the designated position and unload it. Constant speed can make the trolley travel more smoothly and load and unload goods more smoothly.