Abstract:
A probe end module system for an arm comprising: a probe end module having an arm end and an opposing probe end; a module-arm interface located at the arm end; at least one module-probe interface located at the probe end; the arm further comprising a movable member and a movable position reporting device.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention concerns a Probe End Module for Articulated Coordinate Measuring Machines (CMMs) to which probes attach. 
       BACKGROUND TO THE INVENTION 
     Existing Methods of Automated Measurement 
       [0002]    Automated measurement of objects is currently carried out in two main ways: (i) a bulky, expensive, conventional Computer Numerically Controlled Coordinate Measuring Machine (CNC CMM) with 3 or more axes; (ii) a rigid structure of static Optical probes that is typically located in a dedicated cell at the end of the automotive production line. With a conventional CMM, the Optical probe moves in a highly controlled way around a static object to produce accurate data. In the second case, both Optical probes and object are static and localised in a calibrated way that permits accurate data. Most conventional CMMs are of either the moving bridge or horizontal arm structures; companies including Zeiss (Germany), Hexagon Brown&amp;Sharpe (Sweden) and LK (UK) produce them. Mechanical touch probes for mounting on conventional CMMs are supplied by companies including Renishaw (UK). Optical probes for mounting on conventional CMMs are supplied by companies including Metris (Belgium). Automatic probe mounts such as the Renishaw Autojoint are repeatable to a high degree of accuracy and are supplied with a rack of probes for automatic probe changing. Rigid structures of static Optical probes are supplied by Perceptron (USA). 
       Existing Probe End Modules 
       [0003]    Renishaw (UK) with the PH10M, Zeiss (Germany) and Mitutoyo (Japan) provide automated probe end modules to which contact probes such as touch trigger probes are attached. These Probe End Modules are limited to attaching just one probe and have two motorised axes. Optical probe manufacturers such as 3D Scanners (UK) and Metris (Be) have attached optical probes to probe end modules. 
       New Articulated Arm for Automated Measurement 
       [0004]    A Robot CMM Arm with Exoskeleton is a new apparatus for automated measurement disclosed in PCT/GB2004/001827 by Crampton the inventor of this present invention. 
       SUMMARY OF THE INVENTION 
       [0005]    In the prior art, probe end modules for 3-axis CMMs exist that contain two axes of motion. These are entirely suitable for 3-axis CMMs with 3 degrees of freedom. A Robot CMM Arm with Exoskeleton that is articulated with 6 degrees of freedom has now been invented. Existing probe end modules for 3 axis CMMs are not suitable for an articulated Robot CMM Arm with Exoskeleton principally because they have two axes where zero or one axes are required and also because there is only one probe interface for mounting one probe. 
         [0006]    Accordingly, it is an objective of the present invention to provide a probe end module system for an arm comprising: a probe end module having an arm end and an opposing probe end; a module-arm interface located at the arm end; at least one module-probe interface located at the probe end; the arm further comprising a movable member and a movable position reporting device. 
         [0007]    It is a further object of the present invention to provide a probe end module comprising: an arm end; an opposing probe end; a module-arm interface located at the arm end; a static module-probe interface located at the probe end such that there is no relative movement between the module-arm interface and the static module-probe interface; a rotatable module-probe interface located at the probe end; an axis of rotation between the module-arm interface and the rotatable module-probe interface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0009]      FIG. 1  is a schematic of the Probe End Module interfaces; 
           [0010]      FIG. 2  is a diagram of the Probe End Module exoskeleton support; 
           [0011]      FIG. 3  is a diagram of the Probe End Module mounting; 
           [0012]      FIG. 4  is a diagram of the 1-axis Probe End Module; 
           [0013]      FIG. 5  is a section of the hybrid 0/1-axis Probe End Module. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0014]    The first embodiment of this Probe End Module for Articulated Arms invention is now disclosed. The Probe End Module mounts onto the Probe End of an automated Articulated Arm. One or more probes are mounted onto the Probe End Module. The Probe End Module has either zero or one axes of rotation. An automated articulated arm such as a 6-axis Robot CMM Arm is supplied with a Probe End Module such that a customer can convert a standard Robot CMM Arm from 6-axis to 7-axis by removing a 0-axis Probe End Module without an axis and replacing it with a Probe End Module with an additional axis. The Probe End Module concept has advantage to the supplier in that the supplier has one standard 6-axis Robot CMM Arm product that may be simply configured between 6-axis and 7-axis versions by shipping the appropriate Probe End Module. The concept has advantage to the user in that the user can purchase a Robot CMM Arm for 6-axis use and later upgrade to 7-axis use. The Probe End Module is situated at the far end of the Robot CMM Arm; the far end of the Robot CMM Arm is the location that is likely to be subject to most accidents in use. If the Probe End Module is damaged, it may be simply replaced, with little loss of production time. Without the Probe End Module concept, the Robot CMM Arm needs to be swapped out on a production line or cell and a more expensive repair process carried out either onsite or offsite. 
         [0015]    The Probe End Module can be moved by the CMM using any of three broad embodiments:
       Internal endoskeleton finger and transmission means;   External exoskeleton and transmission means;   Mounting interface;
 
as is now disclosed with reference to FIGS.  1 , 2 , 3  using a 0-axis Probe End Module but not limited to a 0-axis Probe End Module. Referring to  FIG. 1 , a Probe End Module  1000  is driven by an Internal endoskeleton finger  1004  through transmission means  77 . The Probe End Module  1000  has three mounting interfaces: Arm Interface  1001 , Contact Probe Interface  1002  and Optical Probe Interface  1003 . The Probe End Module  1000  is rigidly mounted across Arm Interface  1001  to the Internal CMM Arm  5  at CMMSegment 7   37  using appropriate removable fastening means such as bolts. Once mounted, the Probe End Module  1000  is effectively part of CMMSegment 7   37 . The Touch Trigger Probe  96  that is preferably of type Renishaw TP-20 is magnetically mounted across Contact Probe Interface  1002  to the Probe End Module  1000 . Stripe Probe  97  which is preferably a 3D Scanners ModelMaker is mounted across Optical Probe Interface  1003  to the Probe End Module  1000 . Referring now to  FIG. 2 , a Probe End Module  1000  is driven by ExoskeletonSegment 7 ,  47  through transmission means  77 . Referring now to  FIG. 3 , a Probe End Module  1000  is driven through its mounting Arm Interface  1001 .
       
 
         [0019]    Three types of Probe End Module  1000  are disclosed although the scope of this invention is not limited to these three types but includes all types of Probe End Module  1000 :
       0-axis   1-axis   Hybrid 0/1-axis       
 
         [0023]    Referring again to  FIG. 1 , the Probe End Module  1000  is O-axis and is a module between the Robot CMM Arm  1  and one or more Probes  90  preferably a Touch Trigger Probe  96  and a Stripe Probe  97 . Referring now to  FIG. 4 , the 1-axis Probe End Module  1000  is a module between the Arm Interface  1001  and Probe Interfaces  1002 ,  1003  to one or more Probes  90  such as a Touch Trigger Probe  96  and a Stripe Probe  97  such that all Probes  90  rotate on an axis through CMMJoint 7   27 , 57  contained within the Probe End Module  1000 . Referring now to  FIG. 5 , the Hybrid 0/1-axis Probe End Module  1000  is a module between the Arm Interface  1001 , fixed Contact Probe Interface  1002  and rotating Optical Probe Interface  1003 , such that at least one Probe  90  can rotate about a CMMJoint 7   57  contained within the Probe End Module  1000 . Contact Probe Interface  1002  is located on CMMSegment 7   37 . Optical Probe Interface  1003  is located on CMMSegment 8   38 . A through-bore slip-ring is provided comprising static Slip-ring  1005  and rotating Brush block  1006  so that power, signals and communication networks can be continually fed through to a Probe  90  attached via Optical Probe Interface  1003  undergoing unlimited rotation about CMMJoint 7   57 . An electronics module  1010  is contained in Probe End Module  1000  and has a number of tasks including encoder signal processing, motor drive, trigger connections and probe communications. The electronics module  1010  is connected to the Robot CMM Arm  1  via a connector  1011  in the Arm Interface  1001  of the Probe End Module  1000 . The electronics module  1010  is connected to a fixed Probe  90  via a connector  1012  in the Contact Probe Interface  1002  of the Probe End Module  1000 . The electronics module  1010  is connected to a rotating Probe  90  via the slip-ring  1005  and brush lock  1006  to a connector  1013  adjacent to the Optical Probe Interface  1003  of the Probe End Module  1000 . 
         [0024]    CMMJoint 7   27 , 57  contained within Probe End Module  1000  can be driven externally or internally. Referring again to  FIG. 4 , the Probe End Module  1000  is driven externally through TransmissionMeans 8   78  by ExoskeletonSegment 8   48 . It is a purpose of this invention to provide an internally driven 1-axis or Hybrid 0/1-axis Probe End Module  1000 . Referring again to  FIG. 5 , the Probe End Module  1000  is driven internally without an Exoskeleton by Motor  1007  attached to CMMSegment  37  through a spur gear  1008  which is also TransmissionMeans 8   78  to a gear ring  1009  on CMMSegment 8   38 . 
         [0025]    The concept of the Probe End Module  1000  mounted between a Robot CMM Arm  1  and one or more Probes  90  is not limited to the embodiments disclosed above. For example, it is applicable to the mounting of one or more tools  98  or any combination of measuring probes  90  and tools  98 . The 1-axis and Hybrid 0/1-axis Probe End Module  1000  is not limited to provision on Robot CMM Arms  1 . For example, the 1-axis and Hybrid 0/1-axis Probe End Module  1000  can also be provided on conventional 3-axis CMMs such as moving gantry or horizontal arm CMMs; it can also be provided on accurate robots. Any of the interfaces  1001 , 1002 , 1003  may be fixed with strong fixings, sacrificial/breakable fixings that break rather than the Probe End Module being damaged, or magnetic force. Fixings can be provided in a standard arrangement to fit with the wrist design of the machine on which the Probe End Module  1000  is to be mounted; or in non-standard arrangements; or in a flexible design in which it can be mounted in 2 or more different ways. A central fixing can be provided or multiple fixings towards and around the perimeter of the mounting face. Fixings can be non-repeatable or repeatable. Contact Probe Interface  1002  and Optical Probe Interface  1003  can be provided with automatic clamping and unclamping means for probe autochanging. Other drive means may be used instead of the motor with spur gear and ring gear. The 1-axis Probe End Module  1000  can be positioned to any programmed angle to the resolution limits of the system; alternatively the Probe End Module  1000  can be provided with increments such as 15 degs at which it locks in position to a high repeatability; these increments can be datumed. Encoder means are provided for measuring the angle of the CMMJoint 7  within the Probe End Module  1000 . Connectors  1011 ,  1012 ,  1013  may automatically make electrical contact with the Robot CMM Arm  1  or Probe  90  when an interface  1001 ,  1002 ,  1003  is mechanically made. Alternatively Connectors  1011 ,  1012 ,  1013  may be manually made in a separate operation. Markings for the angle of rotation may be made either side of the rotating boundary if the 1-axis Probe End Module  1000 , to enable a user to see approximately what angle the axis has rotated to. The Probe End Module  1000  can contain sensors that will cause an emergency stop on sensing an impact and thereby limit damage. The Probe End Module  1000  can be provided with a curved shape to minimise damage caused in impact by encouraging a sliding movement between the surface of the Probe End Module  1000  and the object with which it is in collision. The scope of the Probe End Module  1000  concept includes Robots, CMMs and Probe End Systems based on the concept of the Probe End Module  1000 . The scope of the Probe End Module  1000  concept is not limited to apparatus but also includes methods of mounting and using the Probe End Module  1000 .