Abstract : High-precision servo systems are conditionally stable due to the use of phase lag correction with significant attenuation. However, the presence of saturation elements in practical systems causes instability under large deviations. A nonlinear correction device is designed using the saturation characteristics of operational amplifiers to address this stability issue. The system design principles are introduced, and the stability of this system with multiple nonlinearities is proven using the phase plane method combined with the describing function method. This expands the system's stable operating range, is easy to implement, and has been successfully applied to a servo turntable control system. Keywords : Servo system; Conditional stability; Saturation; Nonlinear correction The gain of high-precision servo systems typically exceeds 150,000 s⁻². Achieving such high gain requires phase lag correction with significant attenuation, making the system conditionally stable. Due to the high precision, the linear range of the signal sensor is relatively narrow, exhibiting significant saturation characteristics in the system. This causes a decrease in the equivalent gain under large deviations, which implies instability for a conditionally stable system. In other words, high-precision servo systems are generally unstable under large deviations. Large deviation is a relative concept; for the servo system mentioned in this paper, its resolution is 0.0001°, so 1° to 2° is quite large. Therefore, if the system is unstable under large deviations, it generally cannot be properly activated. For this reason, some systems are designed with a segmented activation mode, only activating hysteresis correction when a small signal is received. This paper designs a nonlinear correction device specifically utilizing the saturation characteristics of operational amplifiers, which can ensure that a conditionally stable system can be properly activated and operate stably under large deviations. 1 Nonlinear Hysteresis Correction Device Figure 1 shows the hysteresis correction circuit discussed in this paper. This circuit appears to be a very ordinary active correction network. The idea in this paper is to use special parameter design to utilize the saturation characteristics of the operational amplifier in this active correction to ensure the stability of the entire system under large deviations. [b][align=center]For more details, please click: Nonlinear Correction of High-Precision Servo Systems[/align][/b]