Patent Application
20230075185
The present disclosure relates to industrial robotic systems, and more particularly to a method and system for calibrating a moveable robotic arm at a manufacturing station.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In manufacturing, industrial robotic systems are commonly employed to perform repetitive motions and actions. For example, in the automotive industry, robotic systems having multi-axial robotic arms can be used to transfer workpieces in and out of manufacturing stations. Such robotic systems have typically been fixed to the manufacturing facility, but recent manufacturing developments provide for more dynamic manufacturing facilities in which robotic systems can autonomously move to different manufacturing stations. However, moving the robotic systems to different stations can lead to complex tolerance stack ups that can lead to other issues related to the accuracy at which the robotic systems are able to perform the repetitive motions and actions. These and other issues related to positional control and operation of robotic systems are addressed by the present disclosure.
This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.
In one form, the present disclosure provides a method of operating a robotic system at a manufacturing station in a facility. The method includes moving a locating feature associated with a robotic arm of the robotic system along a selected defined path to a detected position, where the detected position is a position of the locating feature when a force feedback condition is satisfied. The method includes calculating a positional offset of the robotic arm based on a nominal position and the detected position of the robotic arm. The method further includes performing, by the robotic system, one or more operations at the manufacturing station using the positional offset.
In some forms, the method further includes having the robotic arm move the locating feature along a first defined path toward the nominal position, as the selected defined path, measuring force feedback data from one or more sensors provided at the robotic arm to determine whether the force feedback condition is satisfied as the locating feature moves along the selected defined path, and employing a current position of the locating feature as the detected position in response to the force feedback condition being satisfied.
In some forms, the method includes having the robotic arm move the locating feature along a second defined path from the nominal position, as the selected defined path, in response to the force feedback condition not being satisfied when the locating feature is moved to the nominal position.
In some forms, the detected position is provided prior to the locating feature reaching the nominal position.
In some forms, the method includes determining whether force feedback data from one or more sensors provided at the robotic arm is greater than or equal to a force threshold. The method includes determining the force feedback condition is satisfied in response to the force feedback data being greater than or equal to the force threshold.
In some forms, the one or more sensors includes one or more torque sensors.
In some forms, the nominal position is a trained reference position learned by the robotic system during a setup operation.
In some forms, the nominal position is associated with a structural feature of a machine provided at the manufacturing station, a positional fixture provided at the manufacturing station, or a combination thereof.
In some forms, the one or more operations include having the robotic system position a workpiece at a machine, remove the workpiece from the machine, or a combination hereof, where the machine is provided at the manufacturing station.
In one form, the present disclosure provides a robotic system. The robotic system includes a locating feature, a robotic arm associated with the locating feature and includes one or more sensors disposed thereon, and a controller. The controller is configured to move the locating feature along a selected defined path to a detected position, where the detected position is a position of the locating feature in response to a force feedback condition being satisfied at a manufacturing station. The controller is also configured to calculate a positional offset based on a nominal position and the detected position, where the nominal position is associated with the manufacturing station. The controller is further configured to have the robotic arm perform one or more operations at the manufacturing station using the positional offset.
In some forms, the controller is further configured to have the robotic arm move the locating feature along a first defined path toward the nominal position, as the selected defined path, measure force feedback data from one or more sensors provided on the robotic arm to determine whether the force feedback condition is satisfied as the locating feature moves along the selected defined path, and employ a current position of the robotic arm as the detected position in response to the force feedback condition being satisfied.
In some forms, the controller is further configured to have the robotic arm move the locating feature along a second defined path from the nominal position, as the selected defined path, in response to the force feedback condition not being satisfied when the locating feature is initially moved to the nominal position.
In some forms, the detected position is provided prior to the locating feature reaching the nominal position.
In some forms, the controller is further configured to determine whether force feedback data from the one or more sensors at the robotic arm is greater than or equal to a force threshold and determine the force feedback condition is satisfied in response to the force feedback data being greater than or equal to the force threshold.
In some forms, the nominal position is a trained reference position learned by the robotic system during a setup operation.
In some forms, the one or more sensors include one or more torque sensors.
In some forms, the nominal position is associated with a structural feature of a machine of the manufacturing station, a positional fixture associated with the manufacturing station, or a combination thereof.
In some forms, the robotic system further includes an automatic guided vehicle coupled to the robotic arm and configured to transport the robotic arm from a first location to the manufacturing station.
In some forms, the robotic system further includes: a gripper attached to the robotic arm and configured to handle a workpiece. As an operation from among the one or more operations, the controller is configured to have the robotic arm and the gripper position the workpiece at a machine, remove the workpiece from the machine, or a combination hereof, where the machine is provided at the manufacturing station.
In one form, the present disclosure provides a method for operating a robotic system at a manufacturing station in a facility. The method includes moving a locating feature associated with a robotic arm of the robotic system along a selected defined path, where a nominal position is provided along the selected defined path and the nominal position is a trained reference position associated with the manufacturing station. The method includes measuring force feedback data from one or more sensors provided at the robotic arm to determine whether the force feedback condition is satisfied as the locating feature moves along the selected defined path and calculating a positional offset of the robotic arm based on the nominal position and a detected position, where the detected position is a position of the locating feature when the force feedback condition is satisfied. The method includes performing, by the robotic system, one or more operations at the manufacturing station using the positional offset.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
In some applications, a robotic system having a multi-axial robotic arm may operate in tight tolerance (e.g., +/−7 mm or +/−5 mm) to perform manufacturing operations such as positioning workpieces in and transferring workpiece from a machine, such as an automated additive manufacturing production (AAMP) machine. The robotic system of the present disclosure is configured to perform a localization control routine at a selected manufacturing station to improve positional accuracy of the robotic system and more specifically, an end-effector tool of the robotic system that is configured to perform one or more operations at the station. During the localization control routine, the robotic system moves a locating feature associated with a robotic arm along a selected defined path to determine a detected position at which a force feedback condition is satisfied. A nominal position associated with the station is provided along the selected defined path. Once the detected position is obtained, the robotic system calculates a positional offset of the robotic arm based on the nominal position and the detected position, and the positional offset is used to control the robotic arm as it performs one or more operations at the station.
Referring to
In one form, the manufacturing stations 104 are associated with a positional identifier 110-1, 110-2, 110-3 (“positional identifier 110”, collectively) that is employed by the robotic system 102 to locate itself at the station 104, as described herein. In one example, the positional identifier 110 is provided as a structural feature (e.g., positional identifier 110-1) of the AAMP machine 106, such as an opening, a surface, among other features. In another example, the positional identifier 110 is provided as a positional fixture provided at the manufacturing station 104 (e.g., positional identifiers 110-2 and 110-3). In one form, the positional identifier 110 is configured and designed with sufficient strength and rigidity to provide a force feedback that is detectable by the robotic system 102 to determine the positional offset, as disclosed below.
In one form, the robotic system 102 is an autonomous mobile robot that includes, among other components, an automatic guided vehicle (AGV) 112, a robotic arm 113, and a controller 114 configured to control the AGV 112 and the robotic arm 113. The AGV 112 is configured to transport the robotic arm 113 to various locations within the facility 100, such as the manufacturing stations 104 and may include a base for supporting the robotic arm 113, one or more motors for providing drive power, object detection sensors for detecting objects about the system 102, and a power source, among other components.
In one form, the robotic arm 113 is a multi-axial industrial robotic arm to provide rotational and/or translations movement along multiple axes (e.g., six-axis coordinate system). In one example implementation, the robotic arm 113 includes a plurality of joints and a plurality of actuators that can be operated by the controller 114 to provide the multi-axial movement. In one form, the robotic arm 113 further includes multiple sensors 120, an end-effector tool 124, and a locating feature 126. The sensors are configured to measure force feedback at various locations of the robotic arm 113, such as, but not limited to, the joints and/or the end-effector tool 124, and outputs data indicative of the force feedback to the controller 114. The sensors 120 may include torque sensors, load cells, contact sensor, and/or strain gauges, among others.
The end-effector tool 124, also known as end-of-arm-tool, is a mechanical device positioned at the end or at a wrist of the robotic arm 113 and is configured to handle one or more workpieces based on an operation to be performed by the robotic system 102. For example, the end-effector tool 124 is configured to grasp and/or move a workpiece to be installed in and/or removed from the AAMP machine 106. In one example application, the end-effector tool 124 is configured to form an interference fit with the workpiece and thus, the tolerance of the end-effector tool 124 with respect to the workpiece may be tight (e.g., ±0.5 mm). Such an end-effector tool is disclosed in Applicant's co-pending application titled “ROBOTIC GRIPPER APPARATUS” which is commonly owned with the present application and the contents of which are incorporated herein by reference in its entirety. Referring to
With continuing reference to
The controller 114 is configured to control the AGV 112 and the robotic arm 113 to determine the positional offset and perform one or more operations at the manufacturing station 104. Referring to
The AGV control module 304 is configured to control the AGV 112 to move from one location to another location of the facility 100 by operating various components within the AGV 112, such as the motors. For example, the communication module 302 may receive a request to perform an operation at a selected manufacturing station 104 from the manufacturing network system 101. Using prestored digital maps of the facility, the AGV control module 304 is configured to define a route to the selected manufacturing station 104 and control the AGV 112 to travel to the station 104 based on the route and on data from the sensors disposed at the AGV 112, where the sensors detect objects that may impede travel of the AGV 112. In one form, the AGV control module 304 includes data indicative of trained robot reference location for the manufacturing stations 104. In one example application, referring to
Referring to
More particularly, referring to
During the localization control 310, the locating feature 126 is moved along a defined path 500 toward a nominal position 314A to a detected position 504, where the detected position 504 is a position of the locating feature 126 at which a force feedback condition is satisfied (
A start position 506 is provided as a point at which the locating feature 126 begins to travel toward the nominal position 314. In one form, the defined path 500 is a linear path in which a selected coordinate that is being tuned by the localization control 310 is changing and the other two coordinates are not. For example, a defined path 500-1 is provided for the X-axis, a defined path 500-2 is provided for the Y-axis, and a defined path 500-3 is provided for the Z-axis. It should be readily understood that the defined paths are for exemplary purposes only and that the defined path may be provided in other directions (e.g., −Y-axis).
In the example provided in
The localization control 310 is configured to determine the positional offset 316 for the respective axis based on the detected position 504 and the nominal position 314. For example, the positional offset 316 is provided as a difference between the detected position 504 and the nominal position 314 to determine a current position along the defined path 500. Once the positional offset 316 for one axis is determined, the localization control 310 determines the positional offset of the next axis if needed. The positional offsets may then be stored in the memory 306 until the operations are completed and/or the robotic system leaves the station 104. In one form, the localization control 310 is performed each time the robotic system is moved to the manufacturing station 104.
The manufacturing operation module 312 is configured to use the positional offset 316 to perform one or more operations at the specific manufacturing station 104. The positional offset 316 provides a corrected position of the locating feature 126 and since the positional relationship of the locating feature 126 and the end-effector tool 124 is known, the positional offset 316 is used to correct the position of the end-effector tool 124 as it is controlled to perform the one or more operations, thereby improving the accuracy of the operation. In one example application, the one or more operations may include retrieving a workpiece from a staging area, placing the workpiece in the AAMP machine, removing the workpiece from the AMMP machine, and/or placing the workpiece in the staging area, among other operations. In one variation, the robotic arm control module 308 is configured to utilize the positional offset to perform one or more operations at a second related manufacturing station 108, where the AGV 112 maintains its current location. That is, the same positional offset may be employed for two machine stations if the AGV 112 of the robotic system 102 does not move after determining the positional offset.
Referring to
At 606, using force feedback data measured by the sensors provided in the robotic arm, the robotic system determines if the force feedback condition is satisfied. That is, the system determines if the force feedback data is equal to or exceeds a force threshold. If no, the robotic system continues to move along the selected defined path. If yes, the robotic system sets/stores a current position of the locating feature as a detected position, at 608. At 610, the robotic system calculates a positional offset for the respective axis based on the nominal position and the detected position, and stores the positional offset so it can be employed for performing one or more operations at the manufacturing. In one form, the robotic system is configured to calculate a positional offset for one or more axes.
It should be readily understood that the localization control routine employed by the robotic system can be configured in various suitable ways and should not be limited to the example provided here.
Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.
As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
In this application, the term “controller” and/or “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components (e.g., op amp circuit integrator as part of the heat flux data module) that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.
The term memory is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).
The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general-purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.
The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.
