Abstract: The electronically controlled carbon-free trolley is a kind of gravitational potential energy-driven trolley that has both tracking and obstacle avoidance functions, and its speed control is particularly critical. In order to solve the problem of intelligent shifting of carbon-free trolleys according to the slope of the track, an electronically controlled carbon-free trolley based on STM32 was designed using a photoelectric sensor, an infrared pair tube and a touch switch. Experiments show that the car can not only track and avoid obstacles, but also intelligently change speed according to the characteristics of the track. Compared with other electronically controlled carbon-free cars that need to fix the starting point of the track, the advantages are obvious.