Invented by Laurent Desforges, Heinz Lippuner, Knut Siercks, Thibault Duportal, Denis Roux, Jean-Luc Famechon, Hexagon Technology Center GmbH, Hexagon AB
The Hexagon Technology Center GmbH, Hexagon AB invention works as followsA method for operating a CMM with an articulated arm is described. The articulated arm CMM can measure one or more coordinates of an object. The encoders of at least one can be partially turned off. “The encoder can be powered on, and one or multiple coordinates can be measured on the same object without having to recalibrate the encoder.
Background for CMM with improved sensor
Field of Invention
The present invention is a new method of measuring coordinates and articulated arms, more specifically coordinate measurement machines.
Description of Related Art
Rectilinear measurement systems (also known as coordinate measuring machine (CMMs), and articulated arm measurements machines) are used to produce highly accurate geometry data. These instruments are used to capture structural characteristics for quality control, electronic rendering, and/or duplication. A portable coordinate measuring device (PCMM) is an example of a traditional apparatus for acquiring coordinate data. It is a device that is portable and capable of making highly accurate measurements in a device’s measuring sphere. These devices include a probe that is mounted at the end of an arms with a number of transfer members. The joints connect these transfer members. Typically, the end of the arm facing the probe is attached to a moveable platform. The joints are usually broken down into single degrees of rotational freedom. Each of these is measured with a dedicated rotating transducer. The arm probe is manually moved by the operator to different points on the measurement sphere. Each point must have the joint position determined for a specific instant of time. Each transducer produces an electrical signal which varies depending on the degree of freedom of the joint. The probe will also produce a signal. The arm transmits the position signals as well as the probe signal to the recorder/analyzer. The position signals can then be used to determine the location of the probe in the measurement sphere. U.S. Pat. Nos. Nos.
There is generally a need for machines that are accurate, reliable, durable, easy to use and affordable. The disclosure provides improvements to at least some qualities.
In one embodiment, the method for operating an articulated CMM is described. The articulated arm CMM can measure one or more coordinates of an object. The encoders of at least one can be partially turned off. “The encoder can be powered on, and one or multiple coordinates can be measured on the same object without having to recalibrate the encoder.
In another embodiment, the articulated CMM can be composed of an articulated hand with multiple articulated members, a coordinated acquisition member at one end and a base on the other. At least one of these articulation members may include an absolute encoder.
In a further embodiment of an articulated-arm CMM, the CMM may include both an articulated-arm and a tilt sensor. The articulated arms can have a plurality articulating arm members with a measuring probe on a distal and base on a proximal. The tilt sensor may be rigidly attached to the base so that it can detect the tilting angle of base.
In a further embodiment, it is possible to operate an articulated arm CMM. An articulated arm CMM can measure one or more coordinates. The tilt of the CMM articulated arm can be measured at the same time. The CMM can also compensate for tilts when they exceed a certain threshold.
FIGS. According to the present invention, FIGS. 1 and 1A show one embodiment of a mobile coordinate measuring machine 1 (PCMM). In the embodiment illustrated, the PCMM 1 includes a base 10, several rigid transfer members 20 and a coordinate acquisition element 50. It also comprises multiple articulation elements 30-36 which form “joint assemblies”. The rigid transfer members are connected by the articulation members 30-36. The transfer members 20, hinges, and articulation elements 30-36 are all configured to provide one or more degrees of freedom in rotation and/or angle. The PCMM 1 is able to be oriented in different spatial orientations by using the members 3036, 20.
The position of the rigid transfer member 20 and the coordinate acquiring member 50 can be adjusted by manual, robotic, semi robotic and/or other adjustment methods. In one embodiment, PCMM 1 is equipped with seven rotary movement axes through its various articulation elements 30-36. “It will be understood, however, there is no restriction on the number of axes that can be used. In fact, fewer or more axes could be included in the PCMM design.
The embodiment PCMM 1 shown in FIG. The articulation member 30-36 can be divided in two functional groups based on the operation of their motion members, namely, 1) those articulation elements 30, 32,34,36 which are associated with a swiveling movement associated with a distinct and specific transfer member (hereinafter referred to as?swiveling joint? Swiveling joints are articulation elements 30, 32, 34, 36 that allow for a change of the angle between two adjacent members, or between the coordinate acquisition 30 member and its adjacent member. Hinges or hinges? The illustrated embodiment has four swiveling and three hinge joints, arranged to provide seven axes for movement. However, in other embodiments the number and location of the hinge and swiveling joint can be changed to produce different movement characteristics within a PCMM. A device having six axes could, for example, be made with the swivel 30 between the coordinate acquiring member 50 and adjacent articulation 20. In other embodiments, swiveling and hinge joints may be used together or in different combinations.
As known in the art” (e.g. U.S. Pat. No. The transfer members 20 can be a pair of dual concentric tubular structures having an inner tubular shaft 20 a rotatably mounted coaxially within an outer tube sheath (20 b), as shown in FIG. The transfer members 20 of FIG. 2D can include a pair dual concentric tubular structure having an inner tube shaft 20 a mounted rotatably within an outer sheath (20 b) through a bearing located adjacent to the first end of a member, and a bearing located opposite the first end. Both bearings can be mounted within the dual-axis housing 100. The transfer members are used to transfer motion between one end and the other of the transfer member. Transfer members 20 are connected with articulation member 30-36 in order to form joint assemblies.
The hinge joint is formed in part by a combination of the yoke 28, which extends from one end to another of a transfer element (see FIG. The rotational shaft extends through the articulation member 31, 33, and 35, as well as the articulation member 31, 33, and 35 themselves. These rotate around the rotational axis to form a joint or hinge.
Encoder 37 can be seen on FIG. 2C. “Advantageously, both the hinge joint encoders and the swiveling joints encoders can be positioned, at least partially and, more preferably, completely, within the dual-axis housing 100, within the respective articulation member 30-36.
In different embodiments, the coordinate-acquisition member 50 comprises a conductive member 55 (shown as a hard probe on FIG. The probe is configured to contact the surface of an object selected and generate coordinates based on that contact. The coordinate acquisition member 50 in the embodiment illustrated also includes a non-contact scanner and detection component which does not require direct contact to obtain geometry data. The non-contact scanning apparatus includes a noncontact coordinate detection system (shown here as a laser scanner/coordinate detection device) which can be used to acquire geometry data without contacting the object. The non-contact scanner can comprise a camera 70 or another optical device that works in conjunction with the laser, not shown. It will be appreciated that various coordinate acquisition member configurations including: a contact-sensitive probe, a non-contact scanning device, a laser-scanning device, a probe that uses a strain gauge for contact detection, a probe that uses a pressure sensor for contact detection, a device that uses an infrared beam for positioning, and a probe configured to be electrostatically-responsive may be used for the purposes of coordinate acquisition. In some embodiments, the coordinate acquisition member 50 may include two, three or more coordinate acquisition mechanisms.
The U.S. Patent Application Ser. No. No. The entire 2009 document entitled ARTICULATING MESSENGER WITH LASER SCANNER, is hereby incorporated herein by reference. According to said reference, a laser scanner can be attached to the main body (which may also include a probe) of the coordinate-acquisition member. Modular features allow for other coordinate detection devices that can be used in conjunction with the coordinate acquisition device. “Those of skill in this art will also know that other coordinate acquisition members are available.
As shown in FIGS. The articulation elements 30-36 are shown in 2-2C forming a dual-axis house 100. Dual-axis housing 100 may be made of a monoblock or multiple pieces that are bonded together. The dual-axis housing 100 can be a single monoblock, a housing consisting of multiple pieces bonded together (e.g. (Welding, adhesives, etc.) or in any other way. The dual-axis housing can be attached to the transfer members 20, and include part of hinges and swivels, which correspond to the second and the third axes from the base 10. As mentioned above, separate rotational encoders 37 with associated electronics can be placed in the articulation member 34 and 35. (As well as in the articulation member 30-33-36, shown in other figures.)
To simplify assembly of the dual axis assembly, dual axis housing can include removable back cover 102. This is shown in FIG. 2A. As shown, the removable cover can cover a hole in the housing 100 that is generally aligned axially with an adjacent transfer element 20 mounted on the housing. In some embodiments, the removable cover 102 may be configured to not bear any significant load from the CMM 1. It may therefore be desirable to make the cover 102 from a material that is less rigid and can also act as a shock-absorber. The cover 102, as shown in the illustration, can be placed at an “elbow”. The arm 1 is positioned at the?elbow? In some situations, the elbow? During certain activities, the?elbow? A cover 102 made of a shock-absorbing material can be used to protect the arm 1. In some embodiments, the material used for the cover 102 may also be used to enhance sealing with the dual-axis material 100. The dual-axis 100 housing can be made of a rigid material. However, the cover 102 is made from a flexible material which can conform to the edges when mounted. This creates an enhanced seal.
The removable back cover can be used to seal the dual-axis 100 housing from external elements and protect the encoders that are located within. The cover 102 can be removed to expose the encoder 37 that is associated with the articulation element 34. This encoder can then be inserted or removed from the dual-axis 100 housing into the swivel receiving portion 104, which is aligned axially with the transfer member 20 depicted (as shown in FIG. 2E). In the embodiment illustrated, the encoders that are associated with the articulation member 34 and 35 have separate components to the transfer member 20. The encoder and the transfer member are separate components, which are not connected to each other but are able to rotate independently. This principle can be applied to all articulation elements 30-33-36. The transfer members 20 are independent of the articulation member 30-36, which form the joint or joint assembly described above. They can be used to measure rotation.
Also, while the cover 102 102 is being removed, additional electronic components can be added/removed, as shown in FIG. 2B. The dual-axis housing can be configured to receive a printed circuit panel 38, which can contain additional electronics. In some embodiments the additional electronics may perform additional signal processing, such as digitizing the analog signal coming from the encoders. In some embodiments the digitization is performed before passing the signal on to slip rings, or other electronic connections that can rotate. In some embodiments, the printed circuit board 38 may also facilitate the formation of the physical electronic connection that connects both encoders in the dual-axis enclosure 100.Click here to view the patent on Google Patents.