Surface Feature Detection Of Workpiece Based On Laser Scanning

In order to improve the grinding efficiency of workpiece,it is necessary to detect and locate the surface area to be grinded before processing,and then grind it pertinently.The traditional workpiece surface detection method usually relay on labor,and the detection accuracy and efficiency are both low.An automatic detection device is urgently needed to replace the traditional detection method to realize the automatic detection of workpiece surface.Therefore,this paper presents an automatic detection method of workpiece surface based on laser scanning,and studies the key technical problems existing in the process of surface feature detection of workpiece from the following aspects.Firstly,the advantages and disadvantages and costs of different laser measurement methods are analyzed,and the measurement scheme of the automatic detection system of workpiece surface features is determined.Based on that,the hardware of laser sensor and control unit is selected,including the hardware interface of the control unit and the data measurement mode,communication format and wiring of the laser sensor.According to the communication mode of laser sensor and Arduino control chip,the communication transfer module is selected,and the data communication between laser sensor and control unit is realized.Secondly,in order to describe the position information and surface features information of the workpiece more accurately in the laser scanning aera,the laser measuring coordinate system and the workpiece coordinate system fixed on the workpiece surface are built.The scanning principle of laser sensor installed on the robotic arm is introduced.Considering the number of measurement points,measurement period and efficiency,the laser scanning path is designed.Based on that,the distance of the adjacent two measurement points in the direction of x and y axes is set reasonably.Then,aiming at the location problem of workpiece corners in laser measuring coordinate system,the location method of the feature contour point is studied,and the position of the feature contour point of the workpiece in the laser measurement coordinate system is located through the height difference between the adjacent two measurement points.By taking the feature contour point as the research object and taking the Euclidean distance between different feature contour points as reference,the method of detection the connected region is studied,which is used to construct the feature contour boundary line.Based on the above studies,the position of the corner point of the workpiece in the laser measurement coordinate system isobtained by the numerical relationship of the slope between the adjacent three feature contour points in the same connected region.In this paper,the feasibility and accuracy of the above method are verified by the experimental workpiece.Finally,aiming at the detection of workpiece surface features,the expression of the workpiece boundary in the laser measurement coordinate system is fitted by the least squares method according to the minimum value and sub-minimum value point of the x axis coordinates of the workpiece corner point and features contour point.Combined with the slope of the expression and its positive or negative relations,the rotation angle and offset of the workpiece coordinate system relative to the laser measurement coordinate system are obtained.The description of the workpiece surface point in the laser measurement coordinate system relative to the workpiece coordinate system is obtained by the coordinate system transformation,and it is compared with the standard workpiece surface to realize the automatic detection of the grinding area and grinding quantity of the workpiece surface.In this paper,the effectiveness and accuracy of the above method are verified by the experimental workpiece.