Establishment of Stepping Motor Model in CNC Crimping Machine

The control system of the CNC crimping machine is a single-axis open-loop control system. The digital pulse command Xin of the computer is used as input. After the pulse signal distribution circuit and the power drive circuit of the stepping motor drive power source distribute and amplify the pulse signal, the driving step is driven. The motor rotates; the ball screw and the nut pair convert the angular displacement of the stepping motor into the linear displacement of the ram, that is, the system uses the ram displacement Xout as the output.

The establishment of the mathematical model of the control system:

(1) Mathematical model of the conversion link: When the mathematical model of the stepping motor is established, the rotation angle Hi(s) of the stepping motor is taken as the target value. Since the stepping motor is controlled by a digital pulse signal, not the stepping motor angle Hi(s), there is a conversion link from the digital pulse signal to the motor rotation angle. For this numerical control system, the stepping angle of the stepping motor is 75b, which means that the stepping motor rotor rotates one week and needs to receive 480 digital pulse signals; this is an integral link, so the digital pulse signal to the stepping motor angle Hi (s) The transfer function of this conversion link is G1(s)=2P480s=P240s.

(2) Mathematical model of stepping motor: The stepping motor used is a reactive stepping motor. At a certain moment, the motor should move to the specified position (excitation amount) according to the control command, generally from the stable equilibrium point of the previous excitation state. The new equilibrium point rotates, but the actual position H0 of the rotor of the motor may have a slight difference from the amount of excitation for a number of reasons, that is, there is a slight gap between the actual control amount and the target value.

(Finish)