On-line Automatic Detection System For Electrical Characteristic Of Automotive EPB Caliper

As the executive component of EPB(Electrical Parking Brake),EPB calipers provide braking force for automobile brake system.Its performance determines the performance of the whole brake system and has a significant impact on driving safety.In view of the current insufficiency of the on-line testing method of EPB caliper electrical characteristics,and the low degree of test automation,according to the test requirements of enterprises and 《QC/T 592-2013 Hydraulic brake caliper assembly performance requirements and bench test method》,an automatic detection system for EPB calipers based on machinee vision and industrial robot intelligent grabbing and loading is designed.The main research contents are as follows.(1)According to the online test demand analysis,determine the system technical indicators,determine the automatic loading and unloading scheme of the hand-eye system with industrial camera and industrial robot as the core,and clarify the overall scheme of the data acquisition and control system based on the industrial computer and PCI board.(2)According to the special structure of the EPB caliper,determine the gripping position and gripping precision of the EPB caliper,select the industrial camera and the industrial robot,and design the corresponding mechanical tooling according to the automatic detection action of the system.The transformation matrix from image coordinate system to robot coordinate system is determined by nine point calibration method,and the hand eye calibration is completed.The EPB caliper image collected by the camera is binarized and morphological processed,and then the coordinates of the points to be grasped are determined by edge detection and Hough circle detection algorithm(3)According to the test demand analysis of EPB calipers,the detection circuit with fast forward and reverse switching and anti current overshoot function is designed by using solid-state relay and power relay,and the shunt is designed by using micro resistance to realize the peak current collection of products to be tested in the process of adding and settling.The data acquisition and control circuit is designed with PCI6250 data acquisition card as the core,and the threshold method is used to process the collected data to extract the eigenvalues of current and clamping force during the working process of EPB calipers.(4)According to the functional requirements of the detection system,multi-threaded and modular system software is designed based on Lab View,which realizes automatic operations such as automatic capture and electrical property detection,and has functions such as parameter configuration,data acquisition and data management.(5)Select a manufacturer’s model EPB caliper for testing.The uncertainty analysis of the I_peak_apply,I_idle_apply,I_clamp,F_clamp,I_peak_release,I_release,I_idle_release,t_apply of the system meets the system requirements.MSA measurement system analysis method is used to evaluate the measurement repeatability of the system.All the test data of the system meet the requirements of Cg≥1.33.