The mechanical characteristics of motor and load are the stable equilibrium points of judging system.

For detailed analysis, please refer to the related teaching materials of electric drive (some universities may call it "electromechanical drive control"). Mechanical characteristics: can be expressed as a function of rotational speed and output torque; Load characteristics: It can be expressed as a function of speed and load torque. Draw two functions on a chart, which can be used to analyze the working performance of the motor, including applicability, stability and so on. The intersection of two function curves is usually a relatively stable equilibrium working point.