Because it is a simplified version, the original three-loop control of the servo motor is simplified into one loop, that is, only the position loop is detected. The cheap solution is a potentiometer, which is detected by resistance, and the advanced solution is to use a hall sensor, or a grating encoder. Generally, the price of the steering gear is low and the structure is compact, but the precision is very low, and the position stabilization ability is poor, which can meet many low-end needs. With the boom of consumer-grade small robots in the past two years, small and lightweight servos have suddenly become the most suitable joint components. However, the performance requirements of robot joints are much higher than that of rudders, and as a commercial product, the quality requirements of rudders are much higher than those of DIY players.