Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
  • G01B11/275—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment
  • G01B11/2755—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment using photoelectric detection means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
  • G01B11/2408—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures for measuring roundness

Definitions

• the present invention relates to a system used in controlling the shape and alignment of vehicle wheels in general, and to a method of controlling shape and alignment, applied to vehicle wheels in general.
• the steel wheel of an automotive vehicle is usually composed of a rim and a disc. These components are produced by a lamination process and a stamping process, after which the wheel is assembled and welded. For the most part, the shaping processes used in manufacturing the wheel cause an imprecision in the wheel alignment and/or shape.
• Wheels are one of the most important components in an automotive vehicle, and so they should have safety margins even when under severe driving conditions. Their dimensions should be precisely controlled, and so narrow ranges of alignment-deviation tolerance are permitted. For example, for passenger vehicle the ranges of axial and radial tolerance for alignment deviation are approximately between 0.5 and 0.8 mm. On the other hand, the ranges of axial and radial tolerance for alignment deviation for light-load automotive vehicles are of about 1.0 mm.
• the system employed at present for measuring and/or controlling these tolerances in alignment deviation consists in using calibrators, for example, a comparator clock.
• calibrators for example, a comparator clock.
• the wheel is secured to a measuring support, and the calibrators are adjusted close to the measurement points, these points being defined by the contact between the 16 mm diameter sphere positioned on the calibrator and the wheel surface.
• the wheel is manually turned about its axle, and at this moment the alignment deviation is measured.
• This process requires a manual initial adjustment, and the quality achieved in the measurements depends upon the operator's skill to handle and read the comparator clock.
• Another alternative system used in this measurement is based on the contact between the cylindrical rollers and the wheel. However, this system presents imprecision in the measured data due to the impregnation of dust on the roller surface, which causes a bad seating of the roller when it rests on the wheel surface.
• the invention has the objective of providing a system for controlling the shape and alignment of wheels, which comprises:
• control-data generating system the system for processing image and generating contours comprising a processing element associated to the image-capturing device and to the data generating system.
• One also describes a method of controlling the shape and alignment of wheels which comprises the following steps: a) calibrating the system by means of a calibrator; b) capturing an image of the wheel by means of an image-capturing device; c) processing the wheel image by means of an image-processing element, generating and viewing wheel contours by means of a contour-generating element; d) generating control data.
• FIG. 1 is a schematic view of the system for measuring the axial deviation alignment of the prior art
• FIG. 2 is a schematic view of the system for measuring the radial deviation alignment of the prior art
• FIG. 3 is a block diagram of the system for controlling the alignment of wheels of the present invention.
• FIG. 4 is a block diagram representing a first preferred embodiment of the association of the image-capturing device with the image- processing and contour-generating system of the present invention
• FIG. 5 is a block diagram representing a second preferred embodiment of the association of the image-capturing device with the image- processing and contour-generating system of the present invention
• - Figure 6 is a block diagram representing the association of the image- processing and contour-generating system with the control-data generating system of the present invention
• FIG. 7 is a schematic view of the quotas to be controlled by the system for controlling shape and alignment of wheels of the present invention
• - Figure 8 is a schematic view of the calibrator of the system of the present invention
• FIG. 9 is a schematic view of the means for fixing the calibrator and the wheel
• FIG. 10 is a schematic view of the fixing of the calibrator to the means for fixing the calibrator and the wheel;
• FIG. 11 is a view of the image of the orifice of the calibrator, captured by the image-capturing system
• - Figure 12 is a view of the image of the contour of the orifice perimeter of the calibrator, obtained by means of the Sobel algorithm;
• - Figure 13 is a view of the image of the orifice of the calibrator and of the reference straight lines, obtained by means of the Hough algorithm;
• FIG. 14 is a view of the image of the reference straight lines adjusted according to the mathematical method of minimum squares
• FIG. 15 is a schematic view of the fixing of the wheel to the means of fixing the calibrator and the wheel;
• - Figure 16 is a view of the image of the wheel, captured by the image- capturing system
• - Figure 17 is a view of the image of the contour of the wheel, generated with an error by means of the Sobel algorithm
• - Figure 18 is a view of the image of the contour of the wheel, generated without error by means of the Canny algorithm;
• - Figure 19 is a view of the overlapping of the image of the wheel with the contour generated by the contour-generating system;
• FIG. 20 is a view of the overlapping of the image of the wheel with the measurement straight lines.
• FIG. 21 is a schematic view of the points of control of shape and alignment of the wheel.
• Figures 1 and 2 illustrate the system for controlling shape and alignment known from the prior art.
• This system consists in fixing the wheel 1 to a seating base 7 capable of turning the wheel 1 , while a thickness-gauge-clock-type calibrator 5, adjusted in contact with the wheel 1 , records the variations in shape and alignment of this wheel 1.
• Figure 1 illustrates the calibrator 5 positioned so as to record the variations in shape and alignment in the axial direction of the wheel 1
• figure 2 illustrates the calibrator 5 positioned so as to record the variations in shape and alignment in the radial direction of the wheel 1.
• the system for controlling the shape and alignment of wheels 1 of the present invention comprises:
• the image-capturing device 10 has the function of capturing the image of the wheel 1 and sending it to the image-processing and contour-generating system 20.
• the image-capturing system 10 may be an analog-type or digital-type photographic camera or else an analog or digital camera.
• the image-capturing device 10 is positioned on a fixed base, while the wheel 1 is positioned on a rotating base.
• the wheel 1 is then turned at predetermined and adjustable angles, and its images are successively captured by the device 10. It is also foreseen to place the wheel 1 on a fixed base and the image-capture device 10 on a rotating base. In this case, the device 10 is moved around the wheel 1 at predetermined and adjustable angles, while it captures images of the wheel.
• the image-processing and contour-generating system 20 has the function of receiving the images captured by the image-capturing device 10, changing them into digital signals, if necessary, and then processing these images by means of mathematical algorithms, to transform them into measurable contours of the surface of the wheel 1. This obtained contour is then viewed by the user of the system.
• the image-processing and contour- generating system 20 is formed by an image-processing element 22, associated to the image-capturing device 10 and to a contour-generating element 23, which in turn is associable to a viewer 24. Additionally, the image-processing and contour- generating system 20 may also comprise a conversion circuit 21 associated to the image-processing element 22, as illustrated in figure 5.
• This conversion circuit 21 corresponds to a plate for converting analog signals into digital signals, and its function is to convert the analogically captured images into digital signals.
• the image-capturing device 10 will be associated to the conversion circuit 21, in case this device 10 captures analog images (figure 5).
• the image-capturing device 10 will be directly associated to the image-processing element 22 when it generates images in digital signals (figure 4).
• the control-data generating system 30 is formed by a data-processing element 32, associated to the contour-generating element 23, to a keyboard 31 and to a data-generating element 33, which in turn is associated to the view 24.
• the control-data generating system has the function of receiving the contour of the wheel 1 , generated by means of the contour-generating element 23 and, upon a command by the user, transmitted by means of a command input means 31 , generating the requested control data, so that the user can view them through the viewer 24.
• the control data generated by the control-data generating system may be qualitative and/or quantitative data.
• the command input means 31 may be, for example, a keyboard or a mouse.
• the control of the shape and alignment of the wheels 1 is initiated with the control of the diameter D of the wheel 1 and of the width L of the wheel 1 in function of its geometric center. From the intersection point between the straight lines that define the diameter D and the width L of the wheel 1 , one traces the tire seat A, the ⁇ -angle of which is obtained with respect to the axial straight line of the diameter D of the wheel 1. Then, one controls the radius of concordance R between the width L of the wheel 1 and the straight line of the tire seat A.
• This control method comprises the following steps: a) calibrating the system by means of a calibrator 3; b) capturing an image of the wheel 1 by means of an image-capturing device 10; c) processing the image of the wheel 1 by means of an image- processing element 22, generating and viewing contours of the wheel 1 by means of a contour-generating element 23; d) generating control data.
• this system Before using the system for controlling shape and alignment of the wheels 1 , this system has to be calibrated.
• This calibration consists in positioning and fixing a calibrator 3 to the fixing device 2, as shown in figure 10.
• the fixing means 2 has a seating surface 6, where a conical pin 8 is provided and, additionally, an expansive bushing 9.
• the calibrator 3 comprises a first end 15, where there is a fixing bore 17 and a second free end 16 having a quadratic calibration bore 4, positioned in accordance with the coordinates Li, H 1 F L 2 , H 2 , which are pre-established in function of the symmetry axis 10 of the fixing means 2.
• the fixing of this calibrator 3 is effected by fitting or associating the fixing bore 17 with the conical pin 8 and the expansive bushing 9 of the fixing means 2.
• the conventional application of this algorithm foresees the analysis of all the points of the perimeters by means of the Equation 1 , ⁇ ranging from -90° to 90°, and obtaining the corresponding value of p.
• the points pt ⁇ pt 2 , pt 3 and pt t have been obtained, one may determine the point pt m by means of the average of the position of the points pt,, pt 2 , pt 3 and ptj; therefore, the coordinates of pt m will be (447,19; 330,17).
• the reference x of the image will be obtained by means of the distance of intersection points of a horizontal straight line that passes through pt m with the reference straight lines r 3 e r 4 . In this way, we will have:
• the distance between the reference straight lines r 3 and r 4 is given by:
• Equation 11 Analogously, the reference y of the image will be obtained by means of the distance of the intersection points of a vertical straight line that passes by pt m with the reference straight lines r n e r 2 . Therefore, we will have:
• AyTM y r ⁇ ( x P ,m )- y r ⁇ (x ptm ) Equation 12
• the distance between the reference straight lines ⁇ e r 2 is given by:
• the innermost portions of the wheel rim should remain in contact with the seating surface 6 of the device 2.
• step (b) with by adjusting a lighting system (not shown) and capturing the image of the wheel 1 by means of the image-capturing device 10, as illustrated in figure 16.
• the captured image is then sent to the image- processing and contour-generating system 20, and then the step (c) begins.
• a contour of the wheel 1 is generated from the processing of the image of this wheel 1 by means of mathematical algorithms.
• this algorithm did not present good results, since it generated both defined contours and little-defined contours (figure 17) for different captured images of the wheel 1. This is due to the fact that the wheel 1 is cylindrical and is made from a reflexive material, which requires a better controlled illumination. It was then found that, by working with the Canny algorithm, one generates clearer and constant contours, as can be seen in figure 18.
• step (d) the user may request control data of his interest by means of a command-input device 31.
• the contour points that present a normal direction of the straight line of the wheel seat A and of the straight line of the side that defines the width L of the wheel 1 , according to figure 19.
• both the contour of the wheel 1 and the measurement lines 27 may be viewed by the user through the viewer 24.
• the commands received by the command-input device 31 are sent, together with the generated contour, to the data- processing element 32, which, by means of mathematical algorithms, will process the requested data and send them to the control-data generating element 33, which generates data requested by the user and makes the viewable through the viewer 24.
• the data- processing element 32 which, by means of mathematical algorithms, will process the requested data and send them to the control-data generating element 33, which generates data requested by the user and makes the viewable through the viewer 24.
• the generated control data may be arranged in the form of graphs.
• the fixing means 2 is turned at predetermined and adjustable angles, and a new image of the wheel 1 is captured by the image-capturing device 10, whereby one initiates the process again, as described above, that is to say, in general, with each turn of a predetermined adjustable angle, an image of the wheel 1 is captured and processed, its contour is generated and the data requested by the user are viewed through the viewer 24.
• the system does not need the user's interaction in order to function and presents the options: supervised or independent work. If the system is working independently, it is capable of approving or rejecting the product and/or taking the necessary actions depending upon the specification of the product after the information has been processed.
• this system and process enables one to measure the diameter of the wheel, the axial oscillation of the wheel and further enable one to achieve the shape of the wheel, among other possibilities.
• ⁇ is the inclination of the seat, in this case, equal to 5° (figure 7).
• the distance of the r dA is determined by: D 90° ⁇ a
• intersection point I 2 between the side wing straight line r L and the straight line r dA displaced of the wheel seat allows the measure of the axial oscillation of the wheel.
• the axial oscillation of the wheel will be obtained by the variation of the intersection point I 2 between the straight line of the side wing of the wheel r and the straight line r dA , on the axis direction, wherein it is measured in many sections of the wheel 1 completing 360°.
• the radial oscillation of the wheel will be obtained by the variation of the intersection point /, between the wheel seat straight line r A and the straight line r d ) in the radio direction, wherein it is measured in many sections of the wheel 1 completing 360°.
• the algorithms used on image processes, in the obtaining of contours and in obtaining of control data are, preferably, math algorithms found in computer math programs, as for example MATLAB ® .

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Image Analysis (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Image Processing (AREA)

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Citations (5)

• 2002
  • 2002-07-25 BR BR0202870-0A patent/BR0202870A/pt not_active IP Right Cessation
• 2003
  • 2003-05-30 AU AU2003229151A patent/AU2003229151A1/en not_active Abandoned
  • 2003-05-30 WO PCT/BR2003/000068 patent/WO2004011879A1/en not_active Application Discontinuation

Patent Citations (5)

Non-Patent Citations (1)

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