Device for and method of inspecting surface condition

Abstract

A target surface of a target object including portions having different curvatures is inspected by using an illuminating device and a camera that are fixed, a supporting device for supporting the target object such that its position and orientation are variable. The position and orientation of the target object are controlled as its image is obtained for a plurality of times. The position and orientation of the target object are controlled such that the image of any point on the target surface will be included in at least one of the images obtained by the camera.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an inspection device embodying this invention.

FIG. 2 is a drawing for showing the specific structure of the robot and its positional relationship with the optical system.

FIG. 3 is a drawing for showing the positional relationship among the end arm of the robot, a target object and the camera.

FIG. 4 is a schematic drawing of the optical system FIG. 5 is a drawing for explaining the principle of inspecting a surface defect.

FIGS. 6A, 6B and 6C are drawings for explaining the manners in which regularly reflected light is received or not received by the lens of the camera.

FIG. 7 is a drawing for explaining the relationship between curvature and “regular reflection image area.”

FIG. 8 is a drawing for showing examples of target area set for inspection on a target object.

FIGS. 9A, 9B and 9C are graphs for explaining a method of detecting defects.

FIG. 10 is a flowchart of the processes for registering the position and orientation of a target object and data for setting target areas.

FIGS. 11A and 11B show the changes in the orientation of the object in Steps ST4-ST6 of FIG. 10.

FIG. 12 is a flowchart of the inspection process.

FIG. 13A is a graph showing the intensity distribution of the regularly reflected light on the image, and FIG. 13B shows the light irradiating the target object and its relationship with the regularly reflected light the optical system.

FIG. 14 is a drawing for showing the relationship between the lens and regularly reflected light.

FIGS. 15 and 16 are drawings for explaining the principle of obtaining the radius of regularly reflected light.

FIG. 17 is a flowchart of process steps for automatically setting image-taking conditions and data for target inspection area by using CAD data.

FIG. 18 is a drawing for showing the operation of the robot when a side surface of a target object is inspected.

FIG. 19 is a drawing for showing the image-taking direction for the inspection of a side surface of the target object.

FIGS. 20A, 20B and 20C are drawings for showing the image conversion processes for each of the directions shown in FIG. 19.

FIG. 21 is an external view of another inspection device according to a different embodiment.

Claims

1. A method of inspecting condition of a target surface of a target object, said target surface including portions having different curvatures, said method comprising the steps of: carrying out a preparation for sequentially inspecting a plurality of target objects having a same shape;obtaining an image of said target surface by regularly reflected light for a plurality of times by using an illuminating device and a camera that are fixed and by supporting said target object such that the position and orientation of said target object are variable; andprocessing the obtained images of said target surface;wherein said preparation comprises the steps of determining the position and orientation that are to be taken by each of said target objects at each of said plurality times and determining target inspection areas on the obtained images to thereby generate set data that represent results of the steps of determining;wherein said image of said target surface is obtained by supporting said target object in the position and orientation according to said set data; andwherein the position and orientation of the target objects and said target inspection areas are determined such that each of said target inspection areas is determined as the area where the corresponding image by regularly reflected light is obtained or a portion of said area and that the image of any point on said target surface will be included in at least one of said target inspection areas of any of the images obtained in said plurality of times.

2. The method of claim 1 wherein said preparation is carried out by using said camera to obtain a model image of a model object considered to have no defects, supported such that the position and orientation of said model object are variable, said preparation being carried out by displaying said model image on a monitor; wherein said preparation comprises carrying out a first setting unit process on a plurality of specified places on a target inspection surface of said model object serving as target object, said first setting unit process comprising:step A of determining the position and orientation of said target object such that an image including the image by regularly reflected light of a specified place on a target inspection surface of said target object will be displayed on said monitor;step B of determining the area on the image of said target area on which the image by regularly reflected light is obtained or a portion of the area as said target inspection area; andstep C of generating set data representing the position and orientation determined in the step A and the target inspection area determined in the step B; andwherein said plurality of specified places are specified such that the image of said any point on said target surface is included in at least one of the plurality of target inspection areas determined by carrying out said first setting unit process.

3. The method of claim 1 wherein said preparation is carried out by using design data representing three-dimensional shape of said target object; wherein said preparation comprises carrying out a second setting unit process on a plurality of specified places on a target inspection surface of said target object, said second setting unit process comprises:step a of using said design data and thereby obtaining the direction of the normal line to said target surface at a specified position;step b of using said design data and thereby identifying an area on said target object where regularly reflected light can be made incident to said camera if said camera takes an image of said specified position on said target surface along said normal line;step c of obtaining a regular reflection image area on said image taken in said step b, said regular reflection image area being the area on which the area on said target object identified in said step b appears;step d of determining said regular reflection image area or a portion of said regular reflection image area as said target inspection area; andstep e of generating set data that represent the position and orientation of said target object identified by the position of said specified position and the direction of said normal line obtained in said step a and said target inspection area; andwherein said plurality of specified places are specified such that the image of said any point on said target surface is included in at least one of the plurality of target inspection areas determined by carrying out said second setting unit process.

4. A method of inspecting condition of a target surface of a target object, said target surface including portions having different curvatures, said method comprising the steps of: obtaining an image of said target surface by regularly reflected light for a plurality of times by using an illuminating device and a camera that are fixed and supporting said target object such that the position and orientation of said target object are variable; andprocessing the obtained images of said target surface;wherein the image of said target surface is obtained for said plurality of times by sequentially changing the position and orientation of said target object; andwherein said position and orientation of said target object are changed such that the image of any point on said target surface will be included in a target inspection area of at least one of the plurality of obtained images, said target surface area being set as the area where regularly reflected light is to be received or a portion thereof.

5. A device for inspecting condition of a target surface of a target object, said target surface including portions having different curvatures, said device comprising: an illuminating device and a camera that are fixed;a supporting device for supporting said target object such that the position and orientation of said target object are variable; anda control device for controlling the position and orientation of said target object as an image of said target object is obtained for a plurality of times by said camera and by illuminating with said illuminating device;wherein the position and orientation of said target object are controlled such that the image of any point on said target surface will be included in at least one of the images obtained by said camera.

6. The device of claim 5 wherein said supporting device comprises an articulated robot arm having a plurality of shafts; wherein said camera is fixed so as to be able of take images of said target object supported by said robot arm obliquely from above; andwherein said control device serves to attach said target object to an end position of said robot arm as said target object is supplied to a position below said camera and to move said attached target object to another position where said camera can take an image of said target object.