### Electromechanical Dynamic Behaviour and Start-Up

According to Figure 1, the dynamic model of the ball mill is where is the rotation resistance coefficient of the drive motor, is the friction torque, and the rotation direction of the ball mill is determined by the sign function sign().. When the rotational speeds of the clutch are synchronised, i.e., =, the clutch no longer slips. The dynamic model can be written as follows: