The embedded control system of vision inspecting instrument for steel ball surface defect

The detecting instrument for surface quality of steel ball bases on machine vision and image detection technique, and is applied to detecting external bug area of steel ball in bearing. Its control system requires excellent real-time character and high control accuracy. This paper puts forward a new design for mechanism and control system of detecting instrument. We adopted TMS320LF2407A which produced by company TI as main processor, and integrated CPLD to develop an embedded controller. We used the Ziegler-Nichols tuning methods to get PID control and designed hardware circuit. We realized the function of correlative logic elements through programming, and constructed an embedded multitask operating system based on the transplant of muC/OS-II on TMS320LF2407A. The improved method of run length coding was used in registering bug area of steel ball surface to disjoin defect region and irrelevant region after image was segmented. It solved problems about intricate structure and bad real-time character existed in traditional control module. The result of simulation and experiment indicates that this control system satisfied excellently the requirement of high speed and real-time image detection.