Cable robot positioning system utilizing a light beam measurement device

Abstract

A light-based measurement system is capable of directing a light beam to a cooperative target used in conjunction with a cable robot to accurately control the position of the end effector within a large volume working environment defined by a single coordinate system. By measuring the end effector while the device is in operation, the cable robot control system can be adjusted in real time to correct for errors that are introduced through the design of the robot itself providing accuracy in the tens or hundreds of micron range. A coordination processor runs control software that communicates with both the laser tracker and the cable robot. An action plan file is loaded by the software that defines the coordinate system of the working volume, the locations where actions need to be performed by the cable robot, and the actions to be taken.

Claims

1. A cable robot position control system comprising: a) a light beam position measurement system comprising: i) a measurement source that produces an emitted measurement beam that is a light beam; and ii) comprising a cooperative target configured within a device coordinate system that has a target location with respect to the measurement source, which is target data; wherein a single measurement source tracks the cooperative target within a field of view; b) a coordination processor configured to run a control algorithm comprising: i) an input measured position; ii) an output motor command; and iii) end effector activator instructions; c) a cable robot comprising: i) a two or more position drivers; ii) an end effector; and iii) a cable robot mounting structure; wherein the cooperative target is coupled with the cable robot in a fixed positional relationship to said end effector; wherein the measurement source is in a fixed location that is independent of movement of the end effector; wherein the cable robot mounting structure, the two or more position drivers, and the end effector is configured so that the two or more position drivers can take-up and release their cables to position the end effector with respect to the position of said measurement source; wherein said emitted measurement beam is incident on said cooperative target such that said light beam position measurement system produces said target location within a device coordinate system, which is said target data representing the position of the end effector; wherein said target data is provided as an input measured position to said control algorithm to generate said robot positional instructions and said end effector activator instructions; wherein said cable robot receives said output motor command and operates the position driver to set the position of the end effector; wherein said cable robot receives said end effector activator instructions and operates said end effector.

2. The cable robot system of claim 1, wherein said end effector is a nozzle configured to deliver a printable material.

3. The cable robot system of claim 2, wherein said printable material is paint.

4. The cable robot system of claim 2, wherein said printable material comprises concrete.

5. The cable robot system of claim 1, wherein said end effector is a gripper actuator.

6. The cable robot system of claim 1, wherein said end effector is a non-contact measurement device.

7. The cable robot system of claim 1, wherein said end effector is a contact measurement device.

8. The cable robot system of claim 1, wherein said end effector is a camera.

9. The cable robot system of claim 1, further comprising an end effector position mechanism configured between the cable robot and the end effector and configured to move the end effector independently of said cable robot.

10. The cable robot system of claim 1, wherein the position driver comprises a reel means.

11. The cable robot system of claim 1, wherein said cooperative target is a retro reflector assembly comprising: a) two or more retro reflectors; and b) a retroreflector mounting structure; wherein said two or more retroreflectors are coupled to said retroreflector mounting structure such that their relationship to each other is known; where said measurement source measures said two or more retroreflectors such that said target data represents four or more degrees of freedom.

12. The cable robot system of claim 1, wherein said cooperative target is a light receiving target capable of measuring one or more degrees of freedom such that said target data represents four or more degrees of freedom.

13. The cable robot system of claim 1, wherein said cooperative target is a 6 degree of freedom target.

14. The cable robot system of claim 1, wherein said measurement source is a laser tracker.

15. A cable robot position control system comprising: a) a light beam position measurement system comprising: i) a measurement source that produces an emitted measurement beam that is a light beam; and ii) comprising a cooperative target configured within a device coordinate system that has a target location with respect to the measurement source, which is target data; wherein a single measurement source tracks the cooperative target within a field of view; wherein the target data comprises two or more degrees of freedom; b) a coordination processor configured to run a control algorithm comprising: i) an input measured position; ii) an output motor command; and iii) end effector activator instructions; c) a cable robot comprising: i) two or more position drivers; ii) an end effector; and iii) a cable robot mounting structure; wherein the measurement source is coupled with the cable robot in a fixed positional relationship to the end effector; wherein the cooperative target is in a fixed location that is independent of movement of the end effector; wherein the cable robot mounting structure, the two or more position drivers, and the end effector are configured so that the two or more position drivers can take-up and release their cables to position the end effector with respect to the position of said cooperative target; wherein said emitted measurement beam is incident on said cooperative target such that said light beam position measurement system produces said target location within a device coordinate system, which is said target data representing the position of the end effector; wherein said target data is provided as an input measured position to said control algorithm to generate said robot positional instructions and said end effector activator instructions; wherein said cable robot receives said output motor command and operates the position driver to set the position of the end effector; wherein said cable robot receives said end effector activator instructions and operates said end effector.

16. The cable robot system of claim 15, wherein said end effector is a nozzle configured to deliver a printable material.

17. The cable robot system of claim 16, wherein said printable material is paint.

18. The cable robot system of claim 16, wherein said printable material comprises concrete.

19. The cable robot system of claim 15, wherein said end effector is a gripper actuator.

20. The cable robot system of claim 15, wherein said end effector is a non-contact measurement device.

21. The cable robot system of claim 15, wherein said end effector is a contact measurement device.

22. The cable robot system of claim 15, wherein said end effector is a camera.

23. The cable robot system of claim 15, further comprising an end effector position mechanism configured between the cable robot and the end effector and configured to move the end effector independently of said cable robot.

24. The cable robot system of claim 15, wherein the position driver comprises a reel means.

25. The cable robot system of claim 15, wherein said cooperative target is a retro reflector assembly comprising: d) two or more retro reflectors; and e) a retroreflector mounting structure; wherein said two or more retroreflectors are coupled to said retroreflector mounting structure such that their relationship to each other is known; where said measurement source measures said two or more retroreflectors such that said target data represents four or more degrees of freedom.

26. The cable robot system of claim 15, wherein said cooperative target is a light receiving target capable of measuring one or more degrees of freedom such that said target data represents four or more degrees of freedom.

27. The cable robot system of claim 15, wherein said cooperative target is a 6 degree of freedom target.

28. The cable robot system of claim 15, wherein said measurement source is a laser tracker.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

(1) The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

(2) FIG. 1 is a perspective view of an exemplary cable robot system where the coordination processor is a separate device and the reel means is connected to the cable robot mounting structure.

(3) FIG. 2 is a perspective view of an exemplary cable robot system where the coordination processor is integrated with the source measurement device.

(4) FIG. 3 is a perspective view of an exemplary cable robot system where the coordination processor is integrated with the cable robot and the reel means attached to the end effector platform.

(5) FIG. 4 is a perspective view of is an exemplary nozzle distributing printable material.

(6) FIG. 5 is a perspective view of an exemplary gripper.

(7) FIG. 6 is a perspective view of an exemplary screed tool used in conjunction with a light receiving target.

(8) FIG. 7 is a perspective view of an exemplary tamper with the measurement source mounted to cable robot.

(9) FIG. 8 is a perspective view of an exemplary paint nozzle used in conjunction with a corner cube assembly.

(10) FIG. 9 is a perspective view of an exemplary end effector roller.

(11) FIG. 10 is a perspective view of an exemplary cable robot system with two measurement sources and a single cable robot with a non-contact measurement probe.

(12) FIG. 11 is a perspective view of is an exemplary measurement source with a target camera showing the camera's field of view used in conjunction with a contact measurement device.

(13) FIG. 12 is a side view of an exemplary end effector position mechanism.

(14) FIG. 13 is a diagram of an exemplary coordination processor with an action plan.

(15) FIG. 14 is a diagram of an exemplary motion control algorithm.

(16) FIG. 15 is a perspective view of an exemplary light beam position measurement system with a single retro reflector.

(17) FIG. 16 is a perspective view of an exemplary measurement source.

(18) FIG. 17 is a perspective view of an exemplary light beam measurement system with a laser tracker and a light receiving target.

(19) FIG. 18 is a perspective view of an exemplary retro reflector.

(20) FIG. 19 is a perspective view of an exemplary partially transmissive retro reflector.

(21) FIG. 20 is a perspective view of an exemplary retro sphere.

(22) FIG. 21 is a perspective view of an exemplary light receiving target.

(23) FIG. 22 is a perspective view of an exemplary retro reflector assembly.

(24) FIG. 23 is a perspective view of an exemplary cable robot system where the light beam measurement device does not have a beam steering capability.

(25) FIG. 24 is a perspective view of an exemplary camera-assisted 6DOF target.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

(26) As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

(27) Certain exemplary embodiments of the present invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications, combinations and improvements of the described embodiments, will occur to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

(28) FIG. 1 shows an exemplary cable robot system with an end effector mounting structure 130 that couples an end effector 131, a cooperative target 105, and three cables 138, 138′, 138″. A cable robot mounting structure 136, 136′, 136″ comprises a first vertical tower 145, a second vertical tower 146, and a third vertical tower 147 mounted in a fixed relationship to each other that approximately form an equilateral triangle. The reel means 137, 137′, 137″ are comprised of a first motorized spool 139, a second motorized spool 140, and a third motorized spool 141, respectively. A reel means includes any mechanism to take-up and release a cable, such as a motorized spool. Said first motorized spool is coupled to said first vertical tower and a first cable 142. Said second motorized spool is coupled to said second vertical tower and a second cable 143. Said third motorized spool is coupled to said third vertical tower and a third cable 144. Said reel means is then able to adjust the length of said cables to position said end effector within locations defined by working coordinate system 129. A measurement source 101 transmits an emitted measurement beam 102 for which of portion is reflected back by said cooperative target as a reflected measurement beam 103. Said measurement source produces target data 127 that is transmitted to a coordination processor 126, which is a computer 135, such as a laptop computer, running a control algorithm 148. Said computer processes an action plan 132 and sends an action output 128 to said cable robot command processor 5701, 5701′, 5701″ to position said end effector in the working volume defined by working coordinate system 129. Beam steering in said measurement source is accomplished by a moveable mirror that can reflect the beam in two angles.

(29) FIG. 2 shows an exemplary measurement source 101 that has an integrated coordination processor 126 so that a separate external computer is not required. Beam steering is accomplished by a two-axis gimbal that steers the entire optical assembly.

(30) FIG. 3 shows an exemplary cable robot that has an integrated coordination processor 126 and cable robot command processor 5701 so that a separate external computer is not required. Reel means 137, 137′, 137″, 137′″ are coupled to the end effector mounting structure 130 and the cables 138, 138′, 138″, 138″″ are fixed to the cable robot mounting structure 136, 136′, 136″, 136′″, respectively.

(31) FIG. 4 shows an exemplary cable robot with an end effector 131, which is a nozzle 5101 capable of dispensing a printable material 5102 that hardens into a material such as hardened plastic 5103, hardened concrete 5104, or hardened metal 5105.

(32) FIG. 5 shows an exemplary gripper 5108 capable of picking up and placing and exemplary object such as a brick 5109. The exemplary gripper 5108 is an actuator type end effector having at least one of the gripper arms that actuates toward the other gripper arm. The gripper 5108 is holding a brick 5109′, picked up from the stack of bricks. The exemplary gripper is coupled to an end effector position mechanism 5900 that extends from the end effector mounting structure 130 to the end effector 131, the gripper 5108 actuator. The exemplary end effector position mechanism 5900 has a coupled arm 5902 that is coupled with or attached to the end effector mounting structure 130 and an extended arm 5906 that has the end effector 131 coupled or attached thereto. The extended arm is coupled to the coupled arm by an end effector position mechanism actuator 5904, such as a pivoting and/or rotating joint or coupling between the coupled arm and the extended arm. As shown, the end effector position mechanism actuator 5904 enables pivoting between the coupled arm and the extended arm. The coupled arm may have a rotational engagement or coupling with the aerial robot to provide an additional degree of freedom of rotation. An end effector position mechanism actuator may provide translational motion, rotational motion, and/or pivoting motion between a coupled arm and an extended arm of the end effector position mechanism. Also, any number of end effector position mechanism arms may be configured between a coupled arm and an extended arm to provide additional degrees of freedom.

(33) FIG. 6 shows an exemplary screed tool 5110 that is pulled across poured concrete 5111 to level the concrete In this application, it is important to control yaw, so the cooperative target 105, is a light receiving target 5201 capable of measuring yaw.

(34) FIG. 7 shows an exemplary tamper 5112 used to compact a construction material such as sand 5113. Measurement source 101 is mounted to end effector mounting structure 130 in a known and fixed relationship to the end effector 131 and points to a cooperative target 105 mounted in a fixed location.

(35) FIG. 8 shows an exemplary cable robot system where a single measurement source 101 with an exemplary retroreflector assembly 1104 wherein said measurement source alternately measures the location of the reflective targets to calculate locations with six degrees of freedom. An exemplary nozzle 5101 delivers a printable material 5102 that is paint 5202 for an application to paint lines for parking spaces 5203. An exemplary camera 5118 captures images.

(36) FIG. 9 shows an exemplary end effector 131, which is a roller 5801 capable of compacting and smoothing soil 5802.

(37) FIG. 10 shows an exemplary cable robot system with multiple measurement sources 101, where a first measurement source 5401 with a first field of view 5403 and a second measurement source 5402 with a second field of view 5404 extends the operating range of a single end effector 131, which is an exemplary non-contact measurement device 5115, which is a displacement sensor 5116, that projects a displacement light beam 5117 onto a surface 5114, which is able to measure the distance to and the thickness of said surface. The exemplary cable robot system only requires a single measurement source to track the cooperative target within a field of view at a time. As the cooperative target moves from a first field of view 5403 to the second field of view the second measurement source 5402 takes over and produces a light beam that is incident on the cooperative target and the first measurement source disengages.

(38) FIG. 11 shows an exemplary measurement source 101 with a target camera and the ability to illuminate targets within the field of view 5301 of said measurement source. Targets must be rotated so that said measurement source is within the light acceptance angle of the targets 5302. Exemplary contact measurement device 5119 end effector 131 is a probe tip 5120.

(39) FIG. 12 shows an exemplary end effector position mechanism 5501 coupled to the end effector mounting structure 130. Said end effector position mechanism has a translation structure 5503 capable of horizontal motion 5505 and vertical motion 5506. Said end effector position mechanism also has a rotation structure 5502 capable of rotational motion 5504. A nozzle 5101 connected to this structure would have motion in up to five degrees of freedom with respect to said cable robot mounting structure. The end effector command output 5507 from the cable robot command processor will cause said nozzle to open and close as well as reposition. This configuration allows for faster correction to positional disturbances than are capable through the cable robot reel means.

(40) FIG. 13 shows an exemplary coordination processor 126 with a control algorithm 148, and with an action plan 132 read as an input action plan 5603 with one or more operation locations 5601 where the cable robot must be positioned and end effector activator instructions 5602 are executed by the end effector.

(41) FIG. 14 shows an exemplary motion control algorithm 148 executed by the coordination processor 126 that interacts with the control system plant 5704. Target data 127 from the measurement source 101 is transformed to the working coordinate system and is used as an input measured position 5705, which is compared to one or more operation locations 5601. A PI calculation generates an action output 128, which is instructs the cable robot to adjust its position as a cable robot command input 5702. The cable robot command processor 5701 generates an output reel means command 5703 causing the cable robot to adjust its position.

(42) FIG. 15 shows an exemplary light beam position measurement system 133 with a measurement source 101 that transmits an emitted measurement beam 102 toward a cooperative target 105 that is a single retro reflector 1102 reflecting back a reflected measurement beam 103. Said measurement source is capable of measuring the displacement of said emitted measurement beam from said reflected measurement beam. Said measurement source is capable of redirecting said emitted measurement beam so that it tracks the center of said retro reflector. The tracking angle and measured beam displacement combined with a measured distance to the target produce a target location 134 within the device coordinate system 104 defined by said measurement source, wherein the device coordinate system is a three-dimensional cartesian coordinate system; including three orthogonal axes X, Y, and Z as shown. The target locations in the device coordinate system will typically need to be transformed to locations in a working coordinate system.

(43) FIG. 16 shows the front view of exemplary measurement source 101 with a combined measurement source light aperture 112 and source image aperture 114. An exemplary light beam 404 is an emitted measurement beam 102.

(44) FIG. 17 shows an exemplary light beam position measurement system 133 with a measurement source 101, which is a laser tracker 303 with a beam steering assembly capable of moving the entire assembly to direct emitted measurement beam 102. An exemplary light receiving target 106 has a target light aperture 111 that is capable of reflecting a reflected measurement beam 103 as well as measuring rotations around the axes of a light receiving target coordinate system 107.

(45) FIG. 18 shows an exemplary retro reflector 1102, which is a cooperative target 105.

(46) FIG. 19 shows an exemplary partially transmissive retro reflector 1105, which is a cooperative target 105 capable of reflecting a portion of emitted measurement beam 102 as a reflected measurement beam 103 and transmitting the remaining portion as a transmitted measurement beam 1106.

(47) FIG. 20 shows an exemplary retro sphere, which is a cooperative target 105.

(48) FIG. 21 shows an exemplary light receiving target 106, which is a cooperative target 105 capable of measuring the orientation of the emitted measurement beam 102 within the target coordinate system 107. The orientation can be represented in a set of translations and rotations. Said light receiving target is also capable of reflecting a reflected measurement beam 103.

(49) FIG. 22 shows an exemplary retro reflector assembly 1104, which is a cooperative target 105 with two or more retroreflectors 1107 mounted to a retro reflector mounting structure 1108. The measurement source measures each retroreflector 1102 and calculates a six degree of freedom orientation of the target coordination system 107.

(50) FIG. 23 shows an exemplary cable robot system where the measurement source 101 does not have a beam steering capability and therefor is mounted so that emitted measurement beam 102 is parallel to the X-axis of the working coordinate system 129. The robot and measurement devices will have local coordinate systems, which will require transformations to and from locations that are given with respect to the working coordinate system. It is possible to design a system where the different coordinate systems are aligned and therefore the same. Also shown is an exemplary end effector 131 camera 5118.

(51) FIG. 24 is an exemplary cooperative target 105, which is a camera-assisted target 5801, which may be also be referred to as a 6 degree of freedom (DOF) target 5802. An emitted measurement beam 102 for which of portion is reflected back by said cooperative target as a reflected measurement beam 103. In addition, there are camera targets 5800, 5800′, 5800″, that are either reflective or light emitting. A camera combines the image of the camera targets with the position information from the measurement beam to create a six degree of freedom measurement.

(52) It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and/or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.

(53) The following references are hereby incorporated by reference herein. U.S. Pat. No. 4,790,651 Tracking Laser Interferometer, Brown et al. U.S. Pat. No. 4,714,339 Three and Five Axis Laser Tracking Systems, Lau et al. U.S. Pat. No. 5,585,707 Tendon Suspended Platform Robot, Thompson et al. U.S. Pat. No. 6,345,724 Crane Apparatus, Masumoto et al. U.S. Pat. No. 7,753,642 Apparatus and Method Associated with Cable Robot System, Bosscher et al. Martin, Antoine; Caro, Stephane; Cardon, Philippe. Design of a Cable-Driven Parallel Robot with Grasping Device. 28th CIRP Design Conference, May 2018, Nantes, France. U.S. Pat. No. 7,701,559 Absolute Distance Meter that Measures a Moving Retroreflector, Bridges, et al. U.S. Pat. No. 8,525,983 Device and Method for Measuring Six Degrees of Freedom, Bridges et al. U.S. Pat. No. 8,670,114 Device and Method for Measuring Six Degrees of Freedom, Bridges et al. U.S. Pat. No. 8,803,055 Volumetric Error Compensation System with Laser Tracker and Active Target, Lau et al. U.S. Pat. No. 9,976,947 Position Measurement Device, Hoffer Hamann, Marcus; Winter, David; Ament Christopher. Model-Based Control of a Pendulum by a 3-DOF Cable Robot Using Exact Linearization. IFAC Papers Online 53-2 (2020) 9053-9060. Martin, C; Fabritius, M.; Stoll, J. T.; Pott, A. A Laser-Based Direct Cable Length Measurement Sensor for CDPRs. Robotics 2021, 10, 60. https://doi.org/10.3390/robotics 1002060.