3.2. NC system
The task of the automatic scanning control system is to control the probe movement according to the scheduled path, the computer translating and processing the input information, outputting the instruction signal, and giving it to the servo system.
The automatic scanning control system adopts open-loop control, and makes up the NC system and implementation mechanism. In consideration of the system calculating speed and real-time testing, the controller of the system adopts the PC to realize interpolation operation, speed control, direc- tion control and so on. The NC system is composed of a PC, a five-axis stepper motor drive card, five sets of stepper motor power supply, etc., to realize the stepper motor’s control. The control system has the characteristics of a tight-packed constructer, stable working performance, and simplicity and practicality.
The automatic ultrasonic scanning system software includes two main parts: the main procedure and the control procedure. The main procedure consists of a man–machine interface, document management, and inspection procedure edit module, etc., mainly used in system management and interpolation. The control procedure making up the inter- polation calculation, position controlling, speed controlling and some other module, is used to complete the interpolation calculate, position control, etc.