Method and system for the optical determination of correction planes in rotating elements

Abstract

The subject matter of the present invention relates to a system for the optical determination of correction planes in rotating elements, used in the process of balancing, in particular in diagnostic devices equipped with a system which has at least one video camera (K), at least one line projector (RL), a monitor screen (M) and a computer (P) which controls individual component elements of the system, wherein the video camera (K) cooperates with the line projector (RL) while projecting a view of the rotating element (EW) on the monitor screen (M) together with an image of a line (L) projected by means of the line projector (RL). The subject matter of the present invention also relates a method for determining correction planes which consists in that an area of measurement space is defined on the basis of a virtual rotating element (EW) before placing a rotating element (EW) on the shaft of a diagnostic device (PM) onto which line (L) is projected by means of line projector (RL), and subsequently a view of the rotating element (EW) is transmitted by means of the video camera (K) to the monitor screen (M) together with an image of the projected line (L), and thus the run of the line is obtained which maps a change in the value of the radius r.sub.n from the axis of the shaft of the diagnostic device (PM) and the value of distance D.sub.n of the rotating element (EW) from the diagnostic device (PM) in the defined area of measurement space.

Claims

1. A method for the optical determination of correction planes in a rotating element (EW) used in the process of balancing, in particular in diagnostic devices equipped with a system that has at least one video camera (K), at least one line projector (RL), a monitor screen (M) and a computer (P) by means of which these component elements of the system are controlled, the method consisting in that a rotating element (EW) is placed on the shaft of a diagnostic device (PM) in such a manner that the rotating element (EW) is perpendicular to the axis of the shaft of a diagnostic device (PM), characterized in that, prior to placing the rotating element (EW) on the shaft of the diagnostic device (PM), an area of measurement space is determined in such a manner that pre-determined pixels P.sub.n of the monitor screen (M) having coordinates x.sub.n and y.sub.n are assigned to a set of points in the area of measurement space, which pixels are then assigned pre-determined values of radiuses r.sub.n from the axis of the shaft of the diagnostic device (PM) and values of the distance D.sub.n of line (L) projected each time by the line projector (RL) on a virtual rotating element (EW) from the diagnostic device (PM), and in such determined area of measurement space the rotating element (EW) is placed on the shaft of the diagnostic device (PM) onto which a line (L) is projected by the line projector (RL), and subsequently the view of the rotating element (EW) is transmitted by means of the video camera (K) to the monitor screen (M) together with the image of the projected line (L), and thus the run of the line is obtained which maps a change in the value of radius r.sub.n from the axis of the shaft of the diagnostic device (PM) and the value of distance D.sub.n of the rotating element (EW) from the diagnostic device (PM) in the defined area of measurement space, and subsequently a specific pixel P.sub.n having coordinates x.sub.n and y.sub.n is indicated on the monitor screen, which corresponds to the value of radius r.sub.n from the axis of the shaft of the diagnostic device (PM) and the value of distance D.sub.n of the rotating element (EW) from the diagnostic device (PM), which values are used to determine correction planes of the rotating element (EW).

2. The method according to claim 1, characterized in that a determined area of measurement space is stored in the computer (P) memory of the diagnostic device (PM) or on any other data carrier.

3. The method according to claim 1 or 2, characterized in that a determined area of measurement space is defined by the following relation: P.sub.n(x.sub.n, y.sub.n)=f(r.sub.n, D.sub.n), wherein P.sub.n is a pixel number in the matrix of the monitor screen having coordinates x.sub.n and y.sub.n, and f is a function of a projected line (L) on a virtual rotating element (EW) or the rotating element (EW) having coordinates r.sub.n and D.sub.n, wherein r.sub.n is a radius from the axis of the shaft of the diagnostic device (PM) and D.sub.n is a distance from the diagnostic device (PM).

4. A system for the optical determination of correction planes in a rotating element (EW), wherein the system has at least one video camera (K), at least one line projector (RL), a monitor screen (M) and a computer (P) which controls individual component elements of the system, characterized in that the video camera (K) cooperates with the line projector (RL) while projecting a view of the rotating element (EW) on the monitor screen together with an image of a line (L) projected by means of the line projector (RL) on said rotating element (EW), which is positioned on the shaft of a diagnostic device (PM), based on such location of the video camera (K) and the line projector (RL) such that the rotating element (EW) is visible, after previously defining the area of measurement space in such a manner that pre-determined pixels P.sub.n of the monitor screen (M) having coordinates x.sub.n and y.sub.n are assigned to a set of points in the area of measurement space, which pixels are then assigned pre-determined values of radiuses r.sub.n from the axis of the shaft of the diagnostic device (PM) and values of the distance D.sub.n of line (L) projected each time by the line projector (RL) on a virtual rotating element (EW) from the diagnostic device (PM).

5. The system according to claim 4, characterized in that the location of the video camera (K) and the line projector (RL) is fixed.

6. The system according to claim 4, characterized in that the rotating element (EW) is an element of different sizes.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The subject matter of the invention is presented in an example embodiment in relation to the enclosed figures wherein:

(2) FIG. 1 shows a simplified example of a system for the optical determination of correction planes in a rotating element according to the invention;

(3) FIG. 2A shows a simplified method for determining a defined area of measurement space for a virtual rotating element used in the method and system for the optical determination of correction planes in a rotating element;

(4) FIG. 2B shows a defined real area of measurement space according to the method and system for the optical determination of correction planes in a rotating element;

(5) FIG. 2C shows an image of a line on a monitor screen based on a defined area of measurement space of FIG. 2B according to the invention;

(6) FIG. 3 shows an exemplary image presenting a straight line limited to relevant scope of radiuses representing a change, in the area of measurement space, of a radius value at a distance according to the embodiment;

(7) FIG. 4 shows, in the form of a quadrilateral, a set of straight lines of a defined area of measurement space according to the embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(8) The subject matter of the invention is described in detail below with reference to the attached figures and an embodiment. The present invention is not limited only to the detailed embodiment described herein.

(9) In the presented embodiment, FIG. 1 illustrates a system for the optical determination of correction planes with respect to a rotating element (EW), which rotating element (EW) in the embodiment is a rim of different sizes of a vehicle wheel. The said system for the optical determination of parameters of correction planes is composed of a video camera (K), a line projector (RL) located in such a way that the rotating element (EW) is visible, a monitor screen (M), and a computer (P) which controls individual component elements of the system. The entire system has been defined as a functional element of a diagnostic device (PM) in the form of a balancer.

(10) To provide a better view of the essence of the invention of FIG. 1, FIG. 2A presents a simplified scheme of a method of defining an area of a measurement space. The defined area of the measurement space is an area which is determined by a set of points assigned to specific pixels on the monitor screen (M). The essential and key feature of the claimed solution according to the invention consists in that the said area of measurement space is determined before placing the rotating element (EW), which is subsequently subjected to the balancing process, on the shaft of a diagnostic device (PM).

(11) In order to define the above-mentioned area of measurement space, a virtual rotating element (EW) (in the embodiment it is plane (W)) is imposed on the shaft of a diagnostic device (PM) (in the embodiment it is the shaft of the balancer). The said plane (W) is placed in such a way that it is perpendicular to the axis of the shaft of the diagnostic device (PM) and is located at a distance D.sub.1, i.e. a minimum distance from the diagnostic device (PM), which is 10 mm in this case.

(12) The process of determining an area of measurement space consists in that a line is projected from a line projector (RL) onto said plane (W) depicted in FIG. 2A in order to obtain an image of the line, which will be marked as line (L) for the defined area of measurement space. The image of this line is sent by a video camera (K), together with a view of plane (W), to a monitor screen (M). To provide a better picture of the aforesaid, said view has been shown in FIG. 2C as view on the monitor screen (M). In this case, the obtained image of the line (L) is a straight line having an inclination dependent on the position of the video camera (K) and the line projector (RL) relative to the axis of the shaft of the diagnostic device (PM).

(13) The above-mentioned image of the line (L) is displayed on the monitor screen (M) based on specific pixel values P.sub.n(x.sub.n, y.sub.n) corresponding to different values of radiuses r.sub.n relative to the axis of the shaft of the diagnostic device (PM). This is performed in the following way: a minimum value of radius r.sub.1 relative to the axis of the shaft of a diagnostic device (PM), which is 100 mm in the present case, is marked on plane (W) and subsequently the assigned pixel value P.sub.1(x.sub.1, y.sub.1) for that radius r.sub.1 is read on the monitor screen. This operation is repeated for subsequent radiuses r.sub.n, including a random value of radius r.sub.x, which is 280 mm in the present case, and finally for the maximum radius value r.sub.m, which is 500 mm in the present case. In the case of the maximum radius value r.sub.m the assigned pixel value will thus be P.sub.m(x.sub.m, y.sub.m). Therefore, the remaining points on the plane (W) between r.sub.1 and r.sub.m correspond to different radius values r.sub.n and different pixel values P.sub.n(x.sub.n, y.sub.n) on the monitor screen (M).

(14) The above-mentioned pixel values P.sub.n(x.sub.n, y.sub.n) are subsequently stored in the computer memory (P) of the diagnostic device (PM), keeping in mind that they are related to distance D.sub.1, i.e. a minimum distance from the diagnostic device (PM) and they are determined according to the function:
x.sub.1=a.sub.1y.sub.1+b.sub.1
wherein x.sub.1, y.sub.1 represent a pixel number P.sub.1(x.sub.1, y.sub.1) on the matrix of the monitor screen (M) as presented in FIG. 3. This figure presents a straight line with three characteristic magnitudes: magnitude r.sub.1 which is a minimum radius value, magnitude r.sub.x which is a random radius value, and magnitude r.sub.m which is a maximum radius value.

(15) The operation as described above for plane (W) at distance D.sub.1 is then performed each time for subsequent distance D.sub.n in relation to distance D.sub.1. This operation involves displacing the above-mentioned plane (W) along the axis of the shaft of the diagnostic device (PM) up to distance D.sub.m, i.e. a maximum distance from the diagnostic device (PM), which is 500 mm in the present case, through distance D.sub.x which is a random distance from the diagnostic device (PM) and amounts to 150 mm in the present case, as illustrated more precisely in FIG. 2B.

(16) For each individual distance D.sub.n, n measurements as defined above are performed, just as for distance D.sub.1, and thus a set of straight lines is obtained according to the function:
x.sub.n=a.sub.ny.sub.n+b.sub.n
which, having been subsequently stored in the computer memory (P) of the diagnostic device (PM), will be lines corresponding to n.sup.th distance, that is the distance D.sub.n. A set of the straight lines will take a form of a quadrilateral as shown in FIG. 4. Thus, a defined area of measurement space is obtained, which area will define a set of points assigned to specific pixels on the monitor screen (M). The shape of the quadrilateral will be dependent on the location of the video camera (K) and the line projector (RL) relative to the axis of the shaft of the diagnostic device (PM).

(17) On the basis of the above, a similar analysis of an area of measurement space may defined with respect to another virtual rotating element (EW), for example, a cylinder which, like the above-described plane (W), is imposed on the shaft of a diagnostic device (PM) and subsequently line (L) is projected onto an element the cylinder by means of a line projector (RL). When an image has been created on the monitor screen (M) we will obtain a set of lines:
yn=anxn+bn
in the case when the line projector (RL) is coincident with the axis of the shaft of the diagnostic device (PM), or a set of square lines:
y.sup.2n=anx.sup.2n+bnxn+cn
when the line projector (RL) is not coincident with the axis of the shaft of the diagnostic device (PM).

(18) The above-described area of measurement space is defined as an assignment that describes the relation between the value of a radius r.sub.n from the axis of the shaft of the diagnostic device (PM) and the distance D.sub.n of given point in the area of measurement space to a specific pixel P.sub.n(x.sub.n, y.sub.n), wherein n.sup.th pixel P.sub.n is defined as coordinates x.sub.n and y.sub.n of matrix of the monitor screen (M); and thus the equation is expressed as follows:
P.sub.n(x.sub.n,y.sub.n)=f(r.sub.n,D.sub.n)
wherein P.sub.n is a pixel number on the matrix of the monitor screen (M) having coordinates x.sub.n and y.sub.n, and f is a function having coordinates r.sub.n and D.sub.n wherein r.sub.n is a radius from the axis of the diagnostic device (PM), and D.sub.n is a distance from the diagnostic device (PM). This relation may be formulated in the form of a table or as a mathematical function.

(19) In such defined area of measurement space a rotating element (EW) is placed which is subjected to balancing by putting the above-mentioned rotating element (EW) (in the embodiment it is a rim of various sizes of vehicle wheel) on the shaft of a diagnostic device (PM). Subsequently, a line marked as (L) is projected from a line projector (RL) onto the rotating element (EW), i.e. the element being balanced, and thus the run of the line is obtained which will represent a change of radius r relative to the axis of the shaft of the diagnostic device (PM) and of the distance D from the diagnostic device (PM). When indicating a specific place on the monitor screen we indicate a specific pixel number P.sub.n(x.sub.n, y.sub.n), which corresponds to a specific value of radius r.sub.n and distance D.sub.n in the defined area of measurement space.

(20) In the case of balancing vehicle wheels of different sizes it is necessary to determine imbalance correction planes. When watching the rotating element (EW) in the form of a vehicle wheel rim on the monitor screen (M), we indicate a point at which we want to fix a correction weight; having found out what is the corresponding pixel number P.sub.n we know the radius r.sub.n and distance D.sub.n at which the correction plane is located. It is worth noting here that the rotating element (EW) in the form of a vehicle wheel rim has a varied shape resulting from the construction thereof. Thus, line (L) projected from a line projector (RL) and obtained on the monitor (M) is a curved line mapping a change in the value of radius r at a distance D in the area of measurement space. Using the above defined assignment:
P.sub.n(x.sub.n,y.sub.n)=f(r.sub.n,D.sub.n)
the value of radius r.sub.x,1 and distance D.sub.x,1 with respect to pixel P.sub.x,1, and the value of radius r.sub.x,2 and distance D.sub.x,2 with respect to pixel P.sub.x,2 is defined by means of a computer (P). These values unambiguously define correction planes of a rotating element (EW), which, in this case, is a rim of various sizes of vehicle wheel.

(21) The above description of presented embodiment has been provided to enable any person skilled in the art to carry out or use the invention. It is also possible to modify this embodiment in various ways to include all such changes, modifications and variants that fall within the essence and scope of the attached patent claims. The basic principles described herein may thus be applied in other embodiments without extending the scope of the invention. Therefore, the intention of the present invention is not to limit it to the presented embodiment but to make it consistent with the broadest possible scope corresponding to the principles and new features presented herein.

(22) Thus the solution according to the present invention uses the above specified technical means as indicated in FIG. 1 to offer a system for the optical determination of correction planes to be used in the process of balancing, in particular in diagnostic devices, and especially in vehicle wheel balancers. The present system is based on the optical measurement of correction planes with the use of a defined area of measurement space. This system is a component part of the above-described diagnostic devices, in particular vehicle wheel balancers.

(23) The present invention may be used in particular in all applications where there is a need to define points in a geometrical space, specifically correction planes, i.e. in all applications that require balancing of rotating elements in order to avoid vibrations caused by centrifugal force during rotation of an object.

(24) To exemplify, one may mention in particular diagnostic devices, and especially vehicle wheel balancers, in particular for passenger cars, delivery vans and trucks, presented as an embodiment in the description, but also other rotating elements, such as fans, abrasive discs, washing machine drums or hard disk platters in computers.

(25) The invention is thus capable of being used in all applications which require the highest standards of safety, or where there is a need to meet high economic standards (for example, in all applications where unbalanced rotating elements of devices wear out faster or fail more frequently), or finally in all applications that require comfortable operation (i.e. in all applications where unbalanced elements cause noise or vibrations).