Supermarket Shelf Panel Roll Forming Machine system consists of five parts, namely, computer (PC) or PLC composed of the upper control system, servo drive control card, AC servo speed control system (AC servo controller, servo motors, the corresponding control cables, etc.), sensing detection and feedback system and the corresponding auxiliary execution system.
The upper master control system connected to the servo drive control card, you can send the position or speed adjustment commands through the data line, set the PID adjustment parameters (the program design process will be open design, easy to adapt to online adjustment), and digital to analog (D / A) conversion, through the corresponding control board output ± 10V analog signals and through the conversion of the AC servo controller to drive the servo motor, the motor shaft end with an incremental rotary encoder or set up on the controlled object being driven measuring roller and incremental rotary encoder conversion device, and through the rotary encoder to provide feedback signals (A B). The motor shaft end is equipped with an incremental rotary encoder or a measuring roller and an incremental rotary encoder conversion device are set on the controlled object to be driven, and the rotary encoder provides feedback signals (A, B, IN pulses) to complete the position of the servo system in a semi-closed-loop or closed-loop position feedback control system.
The sensing element in the position feedback loop, incremental photoelectric encoder, transmits the real-time displacement (or angle) of the moving parts in the form of A and B phase differential pulses to the on-site control station (PC or PLC) for encoder pulse counting in order to obtain the digitized position, speed and other information, and then the master control host computer calculates the deviation between the given position and the actual position (i.e., the position fed back to the position), and adopts the corresponding PID control strategy. Adopting the corresponding PID control strategy, the digital control role by digital-to-analog conversion into analog control voltage, and output to the servo amplifier, the final regulation of the motor's movement (forward, reverse and positioning stops, etc.), to complete the desired value of the repetition of the multiple positioning in the control principle to achieve a small error in the high-precision rapid position location; auxiliary execution system to complete the corresponding press work cycle to achieve the stamping process, and so on.
Several major issues in control system design
1 Input signal control accuracy
The number of pulses per revolution of the incremental encoder and the circumference of the measuring roll, such as: φ90 measuring roll with 1000 pulses per revolution output photoelectric encoder and 2000 pulses per revolution output photoelectric encoder, φ50 measuring roll and φ90 measuring roll of the difference in the control accuracy; ultimately reflects the length of each output pulse corresponding to the length of the circumference of the length of the ratio between the number of pulses per revolution output, try to choose a product with a small ratio. Try to choose the product with small ratio.
2 Control accuracy of the output signal:
Due to the measurement signal lag and control transmission lag, position loop PID control algorithms on the different, parameter tuning determined by the Kp, Ki, Kd and sampling period T, etc., in the digital PID regulation and control system, in the beginning of the process, the end of the process, or a significant increase in the set value, it will produce the accumulation of integrals, resulting in a larger system overshooting, or even oscillations, which is unfavorable for the operation of servo motors.