Embodiments of the invention generally relate to measurement systems and methods. More particularly, embodiments of the invention relate to distance measurement systems and methods for measurement of a distance to a point of an object.
Machining systems, such as computer numerical controlled (CNC) machines (or “machining centers”) are widely used for machining an object. During machining, dimension, such as a distance to a desired point of the machined object may need to be measured, so that the machining systems can adjust machining parameters to proceed with subsequent machining. Measurement of a distance to a point of an object is desirable to ensure that the objects are appropriately configured or shaped to achieve desirable quality.
There have been attempts to measure the distance to a point of an object. For example, some existing coordinate measurement machines (CMM) are employed to measure the distance to a point of an object. However, the measurement of such an object on the coordinate measurement machines is typically performed offline. In order to measure sizes of the object, machining processes of the object need to be paused so that the object is assembled onto the coordinate measurement machines to perform the measurement.
After measurement, the machining processes of the object may be restarted based on measurement results. However, for a precision object, it is not practical to remove the object from a machine tool and then remount the object on the machine tool due to the errors associated with realigning the object on the machine tool. Generally, such measurement may be performed several times to machine the object with desirable dimensions, which results in a lower productivity, lower quality due to remounting of the object and is time consuming.
In some current applications, touch probes are also employed. The touch probe does not measure the part directly, but rather uses the scales on the machine tool itself to make the measurement, with the touch probe providing a trigger used to take the measurement. The object can be left on the machine by using an on-machine touch probe so there is no loss in quality due to remounting of the object. Although such measurement increases the productivity since the object needs not to be detached from a machining device for measurement by the touch probes, it may be still time consuming due to a relatively long motion time of the touch probes on the object.
Therefore, there is a need for new and improved distance measurement systems and methods for measurement of distances to points of objects while the object is on a machine tool.
A distance measurement system is provided in accordance with one embodiment of the invention. The distance measurement system comprises an optical distance sensor configured to generate a light beam, a first optical module, and a processor. The first optical module is configured to receive the light beam, and generate and selectively transmit a plurality of light beams having different light channels for projection onto one or more points of an object to generate one or more reflected light beams scattered from the respective one or more points of the object, and capture and transmit the one or more reflected light beams into the optical distance sensor to retrieve a plurality of distance data to the respective one or more points of the object. The processor is configured to process the distance data to determine position information of the respective one or more points of the object.
A distance measurement method is provided in accordance with another embodiment of the invention. The method comprises introducing a light beam from an optical sensor into a first optical module, generating and selectively transmitting a plurality of light beams having different light channels for projection onto one or more points of an object to generate one or more reflected light beams scattered from the respective one or more points of the object, capturing and transmitting the one or more reflected light beams into the optical distance sensor to retrieve a plurality of distance data to the respective one or more points of the object, and processing the distance data to determine position information of the respective one or more points of the object.
These and other advantages and features will be more understood from the following detailed description of preferred embodiments of the invention that is provided in connection with the accompanying drawings.
Preferred embodiments of the present disclosure will be described hereinbelow with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail.
In some embodiments, the optical distance sensor 11 may define a stand off distance d1 and a measurement range d2 (shown in
Non-limiting examples of the optical distance sensor 11 may include a laser triangulation sensor, a white light interferometry sensor, or other suitable optical distance sensors for distance measurement. In one non-limiting example, the optical distance sensor 11 comprises a laser triangulation sensor sold under the tradename of Selcom SLS5000, by LMI technologies, of British Columbia, Canada.
As illustrated in
Thus, during operation, the laser source 15 generates and transmits the laser 14 for projection onto the desire point of the object 100. Then, the lens unit 16 captures and transmits the reflected light beam 18 from the point of the object 100 to the position sensitive detector 17 to retrieve the distance to the point of the object 100. For the illustrated arrangement, the lens unit 16 comprises an optical axis (not shown) located at an angle to an axis (not shown) of the projected laser 14 from the laser source 15, which may be referred to as a triangulation distance measurement.
Additionally, as depicted in
For the arrangement in
As depicted in
The reflecting surface 77 of the beam-reflecting element 33 is disposed to be in flush with the splitting surface 74 of the beam splitting element 30. The beam splitting elements 31, 32 are disposed at an upper position and a lower position relative to the beam splitting element 30, and the splitting surface 75 of the beam splitting element 31 is disposed parallel to the splitting surface 74 of the beam splitting element 30 and the splitting surface 76 of the beam splitting element 32 is disposed perpendicularly to the splitting surface 74 of the beam splitting element 30.
Thus, during operation, the light beam 14 is transmitted into the first optical module 12 and is split by the beam splitting element 30 into the light beams 34, 35. The light beam 35 is projected onto the beam splitting element 32 along the projection direction of the light beam 14. Subsequently, the light beam 35 is split into the first light beam 20 and the second light beam 21. The first light beam 20 passes through the beam splitting element 32 and is transmitted out of the first optical module 12 along the first light channel 24, which may be overlapped with the projection direction. The second light beam 21 is reflected out of the first optical module 12 from a left side thereof by the beam splitting element 32 along the second light channel 25 perpendicular to the projection direction.
Meanwhile, the light beam 34 is projected onto the beam splitting element 31 along the direction perpendicular to the projection direction ‘A’ and is split into the third light beam 22 and the fourth light beam 23. The third light beam 22 is reflected along a direction perpendicular to the light beam 34 by the beam splitting element 31 onto the beam-reflecting element 33, and then is reflected out of the first optical module 12 along the third light channel 26 perpendicular to the projection direction. The fourth light beam 23 passes through the beam splitting element 31 and is transmitted out of the first optical module 12 along the fourth light beam spaced away from and parallel to the third light channel.
In some applications, the light beams 20, 21, 22, 23 may be selectively transmitted for projection onto the respective points of the object. In one non-limiting example, one of the light beams 20, 21, 22, 23 may be selectively transmitted for projection onto the object each time. Accordingly, as illustrated in
For some arrangements, after the light beams 20, 21, 22, 23 are projected onto the respective objects, reflected light beams (not shown) scattered back from the respective objects may be captured and transmitted to the optical distance sensor 11 by the first optical module 12 to retrieve the distances to the points of the respective objects. In the illustrated example, for easy illustration, some reflected light beams may not be illustrated. The operation of the optical distance sensor 11, such as a laser triangulation sensor is illustrated in
It should be noted that the arrangement in
Thus, during operation, after the light beam 14 is projected into the first optical module 12, via the beam splitting prisms 44, 45, 46, 47, the first and second light beams 20, 21 are generated. Via the beam splitting prisms 44, 45, 48, 49 and the beam-reflecting prism 50, the third and fourth light beams 22, 23 are also generated. Similarly, a plurality of moveable shutters 40, 41, 42, 43 may also be employed to selectively open and close the respective first, second, third and fourth light beams 20, 21, 22, 23.
In the illustrated example in
In certain applications, the optical distance sensor 11 may also retrieve a plurality of distance data to two or more respective points of the object. As a result, the processor 13 may calculate the position information, such as a distance between two points of the object. In other applications, for the distance measurement of the same one point of the object, the processor 13 may also identify a maximum distance and a minimum distance from the plurality of distance data retrieved by the optical distance sensor 11, and generate the position information, such as a distance difference between the maximum distance and the minimum distance. In non-limiting examples, if the distance difference does not exceed a predetermined threshold distance, the object may be machined normally. If the distance difference exceeds the predetermined threshold distance, the object may be machined abnormally.
For some arrangements, the processor 13 may be not limited to any particular processor for performing the processing tasks of the invention. The term “processor”, as that term is used herein, is intended to denote any machine capable of performing the calculations, or computations, necessary to perform the tasks of the invention. The term “processor” is intended to denote any machine that is capable of accepting a structured input and of processing the input in accordance with prescribed rules to produce an output, as will be understood by those skilled in the art.
In some applications, for the arrangement in
As depicted in
For the illustrated arrangement in
Thus, during operation, the second light beam 21 is reflected by the beam-reflecting element 57 and then is split into the light beams 53, 54 by the beam splitting prism 59. The light beam 53 is projected onto the object (not shown) along a direction perpendicular to the reflected light beam 21. The light beam 54 is reflected and projected onto the object (not shown) by the beam-reflecting prism 60 along a direction opposite to the direction of the light beam 53.
After projection of the light beams 53, 54 onto the respective points of the object, the respective reflected light beams (not shown) scattered from the respective objects may be captured and transmitted to the first optical module 12 by the second optical module 51 for detection by the optical distance sensor 11. Thus, after passing through the second optical module 51, the second light beam 21 may be selectively projected onto one or more points of the object without movement of the distance measurement system 10. In certain applications, the light beams 53, 54 and the respective reflected light beams may be transmitted between the optical distance sensor 11 and the respective objects by the same optical elements of the first and second optical modules 12, 51.
For the illustrated arrangement in
Thus, during operation, the third light beam 22 is split into the light beams 55, 56 by the beam splitting prism 62. The light beam 55 is projected onto the object along a direction perpendicular to the third light beam 22. The light beam 56 is reflected and projected onto the object by the beam-reflecting prism 63 along a direction opposite to the direction of the light beam 55.
Similarly, after projection of the light beams 55, 56 onto the respective objects, the respective reflected light beams (not shown) scattered from the respective objects may be captured and transmitted to the first optical module 12 by the third optical module 52 for detection by the optical distance sensor 11. Thus, without movement of the distance measurement system 10, after passing through the third optical module 51, the third light beam 22 may also be selectively projected onto one or more points of the object. In certain applications, the light beams 55, 56 and the respective reflected light beams may be transmitted between the optical distance sensor 11 and the respective objects by the same optical elements of the first and third optical module 12, 52.
For certain arrangements, one of the light beams 53-56 may be selectively projected onto the respective objects. In some examples, similar to the arrangements in
In other examples, the beam splitting prisms 59, 62 may comprise polarized beam splitting prisms and the distance measurement system 10 further comprise a linear polarizer 64 and a movable half-wave element 65 disposed between the optical distance sensor 11 and the first optical module 12, as depicted in
Thus, as depicted in
Similarly, for the arrangement in
In certain applications, the optical distance sensor 11 may retrieve more than one, for example more than a thousand of distance data to the point of the object. Thus, during measurement of a distance to the point of the upper surface 67, more than one distance data may be retrieved by the optical distance sensor 11 and then be transmitted into the processor 13 for processing to generate a first processed distance. In one non-limiting example, the processor 13 may average the more than one distance data to generate an averaged distance.
Similarly, during measurement of a distance to the point of the lower surface 68, the processor 13 processes the more than one distance data to the point of the lower surface 68, which is retrieved by the optical distance sensor 11, and generates a second processed distance. Finally, the processor 13 may determine the height of the step 66 by calculating the differences between the first and second processed distance distances. In certain applications, the processor 13 may process the distance data after the more than one distance data to each of the two points of the upper and lower surfaces 67, 68 are retrieved.
Similar to the arrangement in
As illustrated in
In some applications, the processor 13 may identify a maximum diameter data and a minimum diameter data from the diameter data retrieved by the optical distance sensor 11 and determine if a diameter difference between the maximum data and the minimum data are larger than a predetermined threshold value. In one non-limiting example, if the diameter difference does not exceed a predetermined threshold value, the object may be machined normally. If the diameter difference exceeds the predetermined threshold value, the object may be machined abnormally.
Similarly, for the arrangements in
In some applications, since the distances may be measured based on the light beams with different light channels, the distance measurement system 10 may be calibrated so that distances to a point, which may be measured via the light beams with different light channels, may be identified in the same one coordinate system, for example, to facilitate communication with a computer numerical controlled (CNC) machining system. That is, after calibration, the distances to a point may be the same, which may be measured by the distance measurement system 10 via the light beams with different light channels. In some examples, the calibration of the distance measurement system 10 may be performed by experiments and/or experiences.
In some embodiments, as illustrated in
For the illustrated arrangement in
In embodiments of the invention, the distance measurement system 10 may generate a plurality of light beams along different light channels. Thus, based on the different applications, for example, measurements of different part features, such as steps and grooves, desired light beams may be selectively generated to perform the measurement, which may be efficient and provide better access capability for measurement of different part features. Compared to the conventional measurement systems, the distance measurement system 10 may generate more than one distance data to a point of an object for being processed so as to provide the position information with high quality. In addition, the distance measurement system 10 may communicate with the CNC machining system to assure the machining quality and retrofit the conventional CNC machining systems.
While the disclosure has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions can be made without departing in any way from the spirit of the present disclosure. As such, further modifications and equivalents of the disclosure herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the disclosure as defined by the following claims.
Number | Date | Country | Kind |
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201010601246.6 | Dec 2010 | CN | national |