This paper discusses the project which is one of the Beijing City College Students’ Scientific Research and Entrepreneurial Action Plan Project named "unmanned area fetching trolley", The project used infrared sensor to measure the distance between the car and the obstacle, The MCU would analyze and process this signal, and generate two different PWM signals respectively to drive motors when the distance is less than a certain value, so as to realize avoiding obstacle automatically. After Hall sensor detected the PWM wave corresponding to the actual speed of the car, the PID module would compare the PWM wave of the actual speed and the PWM wave which is generated by MCU, so as to determine whether the output is desired and achieve closed-loop control, thus can make the control of speed is more precise. The mechanical arm is composed of five steering, the upper monitor control it through the wireless module, each instruction can make the rotation angle of each actuator accurate to 1 degree, so the mechanical arm is flexible and precise. The project ultimately achieved the desired effect that avoid obstacle automatically, upper monitor control accurately. After expansion and improving, it can be used for automatic weeding, automatic cleaning, automatic patrol, automatic sowing, automatic harvesting and so on.