Computer-implemented method for adjusting fastener setting tooling

Abstract

1. A computer-implemented method for adjusting a fastener setting tool, the method comprising: measuring a first parameter associated with a first characteristic of the fastener setting tool; comparing the first parameter to a predetermined parameter, a difference between the first parameter and the predetermined parameter representing a condition of the fastener setting tool; calculating an adjustment based on the comparison, the adjustment being to the first characteristic of the fastener setting tool and / or a second characteristic of the fastener setting tool configured to compensate for a condition of the tool; and applying the adjustment to the fastener setting tool.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a computer-implemented method for adjusting a fastener setting tool, and more particularly to a method for adjusting a fastener setting tool to compensate for tool condition. [Background technology]

[0002] Various fastener setting tools and methods are known for inserting a fastener into a workpiece (e.g., sheet material). For example, a self-pierce riveting tool can be used to insert a fastener into a workpiece without pre-piercing or pre-punching the workpiece. Known self-pierce riveting tools include a punch that can be actuated to drive a rivet into the workpiece. The workpiece is typically supported on a die, and the punch is driven toward the die. Driving the punch toward the die imparts a riveting force or riveting energy to the rivet. When the rivet contacts the workpiece, the riveting force or energy aids in inserting the rivet into the workpiece.

[0003] A rivet inserted into workpieces can join the workpieces and can be referred to as a joint or riveted joint. Variables such as the type of rivet, the type of die, and the amount of riveting force affect the properties of the joint. The properties of the joint can affect the performance of the joint, and there is usually an optimum combination of one or more variables that gives the best performance for a particular joint. The variables are usually selected depending on the materials being joined.

[0004] For an optimum joint, the rivet is inserted so that the rivet head is at a specific height relative to the top surface of the workpiece, where the specific height is typically zero (i.e., the rivet head is flush with the top surface).

[0005] In a non-optimal joint, the rivet may not be fully inserted into the workpiece, so the rivet head protrudes from the top surface of the workpiece. That is, the rivet head is elevated above the surface of the workpiece. Such a non-optimal joint may be referred to as a proud or overflash joint. An overflash joint can occur when the rivet setting energy is too low for the rivet, die, and workpiece combination used.

[0006] Another non-optimal joint is when the rivet is inserted too far into the workpiece, causing the rivet head to be driven too deeply into the workpiece; that is, the rivet head is below the surface of the workpiece. Such a non-optimal joint may be referred to as an indent or underflash. An underflash joint can occur when the riveting energy is too high for the rivet, die, and workpiece combination used.

[0007] Both underflash and overflash joints are typically associated with performance losses in the fastening process, and therefore it may be desirable to precisely control the riveting force used during rivet insertion.

[0008] Known self-pierce riveting tools use an electric motor to drive the punch. Such riveting tools typically include one or more flywheels or other inertial masses along with a tool assembly maintained at a substantially constant angular velocity by the electric motor. The inertia of the tool assembly allows energy to be stored in the tool assembly prior to rivet insertion. The rotational motion of the tool assembly can be converted into reciprocating linear motion. By transferring a portion of the stored inertial energy to the punch in the form of linear motion, the punch can be driven toward or away from the die depending on the spin direction of the tool assembly. This type of tool may be referred to as an inertial rivet setter.

[0009] With an inertia rivet setter, the amount of energy that can be delivered to the rivet has contributions from the inertia of the flywheel, the linear momentum of the tool, and the torque provided by the motor. The amount of energy that can be delivered to the rivet can be reduced by friction losses within the tool. Friction losses can vary depending on the condition of the tool. Conditions can include, for example, temperature, age, fastener characteristics, workpiece characteristics, previous use of the tool, lubrication characteristics (e.g., lubrication amount, lubrication temperature), etc.

[0010] A tool may be in a "cold" state. A tool may be cold when it is at a temperature below the desired operating temperature. A tool may be cold when no insertion cycles have been performed recently. A tool may also be cold when internal friction is high, for example, due to being at a temperature where lubrication is not optimal (e.g., cold), or due to other factors such as the tool being used with new, worn, or damaged parts / components.

[0011] Alternatively, the tool may be in a "hot" state. A tool may be hot when it is at a desired operating temperature. A tool may be hot when sufficient insertion cycles have been performed recently, e.g., within the last 15 minutes. A tool may also be hot when internal friction is low, for example, due to lubrication being at an optimal temperature (e.g., hot), or due to other factors, such as the tool being used with parts / components that are not new, worn, or damaged.

[0012] Alternatively, the tool may be "warm." A warm tool may be between a "cold" and a "hot" state. Summary of the Invention [Problem to be solved by the invention]

[0013] Cold and / or warm tools may experience greater internal friction than hot tools. The increased internal friction may be due to changes in lubrication viscosity and / or lubrication movement and location within the tool, as well as changes in internal component conditions. Thus, it is beneficial to operate hot tools because less driving force is required compared to cold or warm tools. However, it may be necessary to use cold or warm tools, for example, because the tools are cold during initial use. In such cases, it may be beneficial to compensate for friction losses. [Means for solving the problem]

[0014] According to a first embodiment described herein, there is provided a computer-implemented method for adjusting a fastener setting tool, the method including: measuring a first parameter related to a first characteristic of the fastener setting tool; comparing the first parameter to a predetermined parameter, wherein a difference between the first parameter and the predetermined parameter represents a condition of the fastener setting tool; calculating an adjustment based on the comparison, the adjustment being to the first characteristic of the fastener setting tool and / or a second characteristic of the fastener setting tool configured to compensate for the condition of the tool; and applying the adjustment to the fastener setting tool.

[0015] The performance of a fastener setting tool can vary depending on the tool's condition, for example, when the tool is cold, warm, or hot. This method can be used to compensate for variations in tool performance. In particular, losses can be indirectly determined by measuring a first parameter and comparing it with a predetermined parameter. A compensation method can then be obtained by calculating and adjusting the same. Such a compensation method can be beneficial for improving tool performance.

[0016] The predetermined parameter may be a theoretical value, an empirical value measured in a previous insertion cycle of the fastener setting tool, an empirical value measured early in the same insertion cycle, or a combination thereof. The predetermined parameter may be an expected parameter. The predetermined parameter may be a parameter related to a first characteristic. The first parameter may be measured at a time when the first characteristic is substantially constant.

[0017] The condition may represent one or more of the temperature, age, usage history, and lubrication status of the fastener setting tool or its components.

[0018] Temperature may include a current temperature compared to an optimum operating temperature. Age may include time since manufacture or time since a maintenance event, such as calibration or servicing. Usage history may include previous usage of the tool, such as the number of previous fastener insertions performed by the tool and / or the time since the most recent insertion performed by the tool. Lubrication condition may include lubrication temperature, lubrication chemical composition, lubrication age, lubrication quantity, lubrication location or distribution. Components of a fastener setting tool may include the tool itself and / or component parts of a workpiece fastened by the tool.

[0019] The first characteristic can be one of the torque of a motor of the fastener setting tool or the speed of a fastener of the fastener setting tool. The torque of the motor can be measured and / or expressed as motor speed or electrical impulse applied to the motor. The fastener can include, for example, a punch, a fastener, or a setter of the tool. The speed of a fastener in or on the fastener of the tool can be measured, rather than the speed of the fastener itself.

[0020] The second characteristic can be the other of the torque of a motor of the fastener setting tool or the speed of a fastener of the fastener setting tool. The torque of the motor can be measured and / or expressed as motor speed or electrical impulse applied to the motor. The fastener can include, for example, a punch, a fastener, or a setter of the tool. The speed of a fastener in or on the fastener of the tool can be measured, rather than the speed of the fastener itself.

[0021] The measurement of the first parameter may be performed when the second characteristic is at a predetermined second parameter, which may be related to the second characteristic.

[0022] If the first characteristic is motor torque, the measurement of the first parameter may be performed when the fastener speed is at a predetermined speed. Alternatively, if the first characteristic is fastener speed, the measurement of the first parameter may be performed when the motor torque is at a predetermined motor torque.

[0023] The method may further include inserting the fastener with the adjusted fastener setting tool. The fastener setting tool may be referred to as an adjusted fastener setting tool after applying the adjustment.

[0024] Measurements can be performed and adjustments can be applied during the first fastener insertion cycle. By measuring, calculating, adjusting, and applying the adjustments during a single insertion cycle, tool conditions can be compensated for before fastener insertion.

[0025] The measurement can be performed during a first fastener insertion cycle and the adjustment can be applied during a second fastener insertion cycle. The adjustment can be applied during the second fastener insertion cycle while the measurement of the first parameter is not performed during said second fastener insertion cycle. The adjustment can be applied during additional fastener insertion cycles, for example, the adjustment can be applied over 10 or 20 cycles.

[0026] The method can further include determining a state of the fastener setting tool, for example, the state can be estimated based on a difference between the first parameter and a predetermined parameter.

[0027] Adjustments can be applied only if conditions meet a predetermined condition. Adjustments can be applied only if conditions are not optimal. For example, adjustments can be applied for multiple insertion cycles while the tool condition is cold or medium, and can be stopped once the tool condition is deemed hot.

[0028] The comparison can be further based on one or more stored parameters, where the one or more stored parameters correspond to parameters associated with the fastener setting tool measured before measuring the first parameter. The stored parameters can be stored in a memory device of the fastener setting tool.

[0029] The method can be performed iteratively to form a feedback loop.

[0030] Multiple measurements of the first parameter can be taken. The multiple measurements can be averaged to produce a single measurement. The averaging of measurements can be performed on measurements occurring over one revolution of the motor. The averaging can be weighted, for example, based on the position within the revolution of the motor at the time of the measurement and / or based on a confidence value. The confidence value can be based on a comparison of the measured measurement(s) of the first parameter to a previous measurement of the first parameter and / or a theoretical value associated with the first parameter. Each of the multiple first measurements can be taken when the motor of the fastener setting tool is in a predetermined orientation.

[0031] The multiple measurements may be taken when the first characteristic and / or the second characteristic are substantially constant. For example, if the first characteristic is tool speed, the measurements may be taken when the speed is substantially constant, such as while the setter is advancing at a constant speed. For example, if the first characteristic is motor torque, the measurements may be taken when the torque is substantially constant. Note that the term "substantially constant" is intended to allow for slight vibrations and / or noise and / or drift associated with the first characteristic and / or the second characteristic, and such vibrations do not cause the characteristics to be "non-constant."

[0032] The first parameter associated with the multiple measurements may be averaged. The averaging may depend on the rotation time of the motor of the tool.

[0033] The adjustment may include an instruction to increase electrical stimulation provided to a motor of the fastener setting tool. Applying the adjustment may include providing the instruction to a data processing system of the fastener setting tool.

[0034] The method may further include providing an alert based on the condition of the fastener setting tool. The alert may include an indication of a need for inspection and / or repair of the tool. The alert may be provided in response to a threshold exceeding condition. The alert may be provided as a result of the tool condition exceeding a threshold while other characteristics of the tool are within tolerances, such as when the tool condition is suboptimal despite the tool being operating at a theoretically optimal operating temperature.

[0035] According to a second embodiment described herein, there is provided a fastener setting tool comprising: a sensor operable to measure a first parameter related to a first characteristic of the fastener setting tool; a data processing system including means for performing the steps of comparing the first parameter to a predetermined parameter, wherein a difference between the first parameter and the predetermined parameter represents a condition of the fastener setting tool; calculating an adjustment based on the comparison, the adjustment being to the first characteristic of the fastener setting tool and / or a second characteristic of the fastener setting tool configured to compensate for the condition of the tool; and providing instructions to the fastener setting tool comprising the adjustment; and means for applying the adjustment to the tool.

[0036] According to a third embodiment described herein, there is provided a computer-readable medium containing instructions that, when executed by a data processing system of a fastener setting tool, cause the tool to perform the steps of the first embodiment.

[0037] Also described herein is a computer-implemented method for adjusting a fastener setting tool, the method including measuring a first parameter associated with a first characteristic of the fastener setting tool during a first insertion cycle of the fastener setting tool, comparing the first parameter to a predetermined parameter, calculating an adjustment based on the comparison, applying the adjustment to the fastener setting tool, and inserting a fastener with the adjusted fastener setting tool during the first insertion cycle.

[0038] The invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a schematic longitudinal cross-sectional view of an exemplary fastener setting tool. [Figure 2A] 1 shows a simplified relationship between motor torque and setter speed during a first type of insertion cycle. [Figure 2B] 1 shows a simplified relationship between motor torque and setter speed during a second type of insertion cycle. [Figure 3] 1 illustrates an exemplary compensation method. [Figure 4] 10 illustrates motor torque and setter speed for an exemplary insertion cycle of a tool using an in-cycle compensation method. [Figure 5] 1 illustrates an exemplary compensation method. [Figure 6] 1 illustrates an exemplary compensation method. [Figure 7] 1 illustrates an exemplary compensation method. [Figure 8] 1 shows an exemplary table used to store parameter values. [Figure 9] The method used to improve the reliability of the calculated adjustments is shown. [Figure 10] 1 illustrates an exemplary compensation method. [Figure 11A] 1 shows data from a fastener setting tool without compensation methods. [Figure 11B] 1 shows data from a fastener setting tool using a compensation method. [Figure 12] 1 shows raw and smoothed data from a fastener setting tool. [Figure 13] 1 shows raw and smoothed data from a fastener setting tool. [Figure 14] The averaging method is shown below. DETAILED DESCRIPTION OF THE INVENTION

[0040] The present invention will be described with reference to a fastener setting tool. Particularly, an exemplary fastener setting tool for use with a self-piercing rivet setting machine of the type that sets self-piercing rivets will be described. For example, the self-piercing rivet setting tool may be used with workpieces and plates of various thicknesses for the manufacture of vehicle bodies, such as automobile frames and / or panels. However, it will be understood that the invention is not so limited, and that the configurations described herein may also be applicable to other fastener setting tools and fastener setting tools used in the manufacture of other items. Furthermore, while particularly suited to rivets, it will be understood that the present invention may also be applicable to other fasteners, such as screws, nails, and studs.

[0041] An exemplary fastener setting tool 2 is shown schematically in FIG. 1. The fastener setting tool may be referred to herein simply as the tool. The tool 2 is mounted on a conventional C-frame 1, which holds a die 6 that counteracts the forces generated by the tool during rivet insertion. Fastener setting tools are often incorporated into robotic systems so that they can be moved and positioned where needed within a work area according to many different orientations. To accomplish this, the tool 2 is mounted to a C-frame, which is in turn mounted to the robotic system.

[0042] Tool 2 is used to insert rivet 5 into a workpiece (not shown) located between nose 22 of tool 2 and die 6 mounted on the C-frame 1 on the side of the C-frame opposite tool 2. Directional terms may be used herein with respect to the workpiece, such as moving towards or away from the workpiece. These directional terms should be interpreted with respect to the workpiece in position during normal operation, i.e., located between nose 22 of tool 2 and die 6.

[0043] The tool 2 includes a drive assembly 4 operable to drive a linear actuator assembly 3. The drive assembly 4 includes an electric motor 10. An output shaft 11 of the motor 10 is typically connected in parallel to the linear actuator assembly 3 via, for example, an endless toothed belt 12 and a drive pulley (not shown). The linear actuator assembly 3 converts rotational motion of the motor output shaft 11 into reciprocating linear motion of an elongated output shaft 15 connected to a plunger 16 of the tool 2.

[0044] The tool 2 is connected to a control system (not shown) that incorporates a data processing subsystem. The data processing system is operable to provide instructions to components of the tool. For example, the data processing system may be operable to provide instructions to vary the speed of the electric motor 10. The data processing system may include a servo controller. The data processing system may further include a memory operable to store parameters associated with one or more portions of the tool 2. For example, the data processing system may be used to store historical data regarding the speed of the electric motor 10 and / or the condition of the tool 2.

[0045] The tool 2 includes a housing 20 within which a clamping tube 21 is slidably disposed. A nose portion 22 is provided at the end of the clamping tube 21. The nose portion 22 is disposed coaxially with the clamping tube 21 and has a rivet feed passage 23 through which the rivet 5 can be guided into a workpiece. The rivet 5 is moved through the feed passage 23 by a punch 24 carried by a plunger 16. The punch 24 and plunger 16 are disposed for reciprocating axial movement within the clamping tube 21 and the feed passage 23 and are driven by the output shaft 15 of the linear actuator assembly 3. The output shaft 15, plunger 16, and punch 24 may collectively be referred to as a setter.

[0046] The linear movement of the output shaft 15 moves the plunger 16 and punch 24 relative to the housing 20 of the tool 2 and toward the workpiece. This movement continues until the end face of the nose 22 contacts the workpiece, preventing further advancement of the clamping tube 21. As the output shaft 15 continues to extend, the setter moves relative to the clamping tube 21 and nose 22. The rivet 5 to be inserted is driven through the feed passage 23 and into contact with the workpiece. Further advancement of the setter drives the rivet 5 into the workpiece.

[0047] The insertion of a single fastener may be referred to as an insertion cycle. During an insertion cycle, tool 2 begins in an initial position, moves rivet 5 through rivet feed passage 23 toward the workpiece, drives rivet 5 into the workpiece, and then moves to a final position. That is, the insertion cycle described herein includes all of the movement of tool 2 necessary to set rivet 5; rivet 5 is only physically driven into the workpiece during a portion of the insertion cycle.

[0048] The rivet 5 is advanced towards the workpiece at a rivet speed, which may be different at different times and / or positions within the insertion cycle. The rivet speed is set by the speed of the setter. Thus, the rivet speed during its advance towards the workpiece may be referred to as the setter speed. The setter speed may be considered as the speed of the fastening part (i.e., the setter) of the tool 2.

[0049] The tool 2 is provided with means for measuring speed so that the setter speed and / or rivet speed can be measured during the insertion cycle. For example, the tool 2 may be provided with at least one sensor capable of measuring speed, such as a speed encoder (not shown). The speed can be measured directly or indirectly. That is, the tool 2 may be provided with means for measuring the displacement of the setter and / or rivet (displacement is velocity multiplied by time). The rivet and / or setter acceleration can also be calculated from the measured speed, time, and / or displacement data. The measured data is provided to a data processing system.

[0050] The rivet may be accelerated to reach a required set speed before contacting the workpiece. The required set speed may be selected to provide an optimal rivet insertion force for a given insertion cycle. The required set speed may be selected to optimize one or more characteristics of the insertion cycle. For example, the required set speed may be selected to provide an optimal rivet insertion force for a given insertion cycle. The required set speed may be selected depending on the properties of the fastener (e.g., material, diameter, length) and / or the properties of the workpiece (e.g., thickness, material).

[0051] After insertion, the rivet velocity relative to the workpiece is effectively zero. Once the rivet is inserted, the direction of rotation of the motor output shaft is reversed to retract the setter in preparation for the insertion of the next rivet.

[0052] The servo control system includes a servo controller for the motor that operates under the control of a suitable computer program. The program operates to issue commands to the servo controller that control the torque of the motor. For example, the commands can cause a change in position or velocity over time based on a position profile or velocity profile. By controlling the movement of the motor, the rivet velocity, and therefore the position, can also be controlled. Generally, a higher torque over a given time will accelerate the rivet to or maintain it at a higher velocity compared to a lower torque.

[0053] 2A shows a simplified relationship between motor torque and setter speed for a first type of insertion cycle at various setter conditions (low, medium, and high temperature). The insertion cycle can be described in terms of several phases: forward acceleration 200, actual speed acceleration 206, rivet insertion 208, retract acceleration 210, actual speed retraction 212, and retraction deceleration 214.

[0054] Forward acceleration 200. The setter starts at an initial position. The initial position may be the position where the tool is retracted as far as possible from the workpiece, called the home position (e.g., the travel limit allowed by the tool). The initial position may be between the home position and the workpiece, but should be far enough from the workpiece to be able to reach the required settling speed.

[0055] The motor 10 is commanded to accelerate the tool 2 toward the workpiece at a given rate to the required set speed. During acceleration, the amount of motor torque required to maintain acceleration will vary depending on the condition of the tool 2, for example, whether the tool 2 is cold, warm, or hot. As can be seen in Figure 2A, a cold tool may require more acceleration torque to provide a given acceleration (i.e., to accelerate the setter to the required set speed in a given amount of time) than a warm or hot tool.

[0056] Actual Speed ​​Advance 206. Once the required make-up speed is reached, the motor torque is reduced to a value that will maintain the setter at the required make-up speed. The torque during Actual Speed ​​Advance 206 may be referred to as coast torque. Coast torque is applied to overcome losses due to resistance (e.g., friction) present in the tool. The required coast torque may vary depending on the condition of the tool, for example, whether the tool is cold, warm, or hot. As can be seen in FIG. 2A, a cold tool requires more coast torque to maintain the required make-up speed compared to a warm or hot tool.

[0057] Before the forward acceleration 200 begins, the rivet 5 is loaded under the setter punch 24 and is therefore accelerated to the required setting speed along with the nosepiece 22. Once the nosepiece 22 contacts the workpiece, the rivet 5 continues to be driven by the punch 24 and advances through the nosepiece 22 until the rivet 5 reaches the workpiece.

[0058] Rivet Insertion 208. The rivet contacts the workpiece while proceeding at the required setting speed, at which point it is suddenly decelerated and begins to be inserted into the workpiece. Rivet deceleration slows the setter. To maintain the setting speed during rivet insertion, the motor torque is suddenly increased to provide additional torque. The additional torque is limited to a predetermined maximum, which may be referred to as a torque limit. The combination of setter deceleration and additional torque contributes to the insertion force applied to the rivet, which inserts the rivet into the workpiece. The torque limit may be selected depending on the desired insertion force. For example, a larger torque limit may be selected to provide a larger insertion force or in response to an increase in setting speed.

[0059] During the exemplary insertion cycle shown in Figure 2A, the torque limit is adjusted based on the condition of the tool, for example, whether the tool is cold, medium warm, or hot. In this example, the torque limit is greater for a cold tool compared to a medium or hot tool.

[0060] During rivet insertion 208, the rivet continues to be inserted into the workpiece until it slows down to a substantially zero speed, at which point the setter has correspondingly slowed down to a substantially zero speed.

[0061] Retract Acceleration 210. The direction of the motor torque is reversed to accelerate the setter in the opposite direction, i.e., retracting the setter away from the workpiece. The setter is accelerated to a retract velocity. As with forward acceleration 200, the motor torque required to maintain acceleration can vary depending on the condition of the tool, for example, whether the tool is cold, warm, or hot.

[0062] Actual Speed ​​Reverse 212. Once the retract speed is reached, the motor torque may be reduced to a value that will maintain the setter at the retract speed. As with Actual Speed ​​Forward 206, the amount of torque required to maintain the retract speed may vary depending on the condition of the tool, for example, whether the tool is cold, warm, or hot.

[0063] Retract Deceleration 214. After actual speed retract 212, the tool is decelerated to a stop (zero speed). The deceleration is accomplished by reversing the direction of the motor torque. The time and / or tool position at which the retract deceleration 214 phase begins is selected based on the retract speed, the deceleration rate, and the desired final position. The final position is the point in the space between the home position and the minimum distance from the workpiece at which the next insertion cycle can begin, including the home position. The final position may be referred to as the end position.

[0064] As with the forward acceleration 200 and reverse acceleration 210, the motor torque required to achieve the required deceleration may vary depending on the condition of the tool, for example, whether the tool is cold, warm, or hot.

[0065] FIG. 2B shows a simplified relationship between motor torque and setter speed for a second type of insertion cycle at various setter conditions (low, medium, and high temperatures). The insertion cycle can be described in terms of multiple phases: forward acceleration 200, fly-across space (FAS) 202, FAS deceleration 204, actual speed acceleration 206, rivet insertion 208, retraction acceleration 210, actual speed retraction 212, and retraction deceleration 214. The second type of insertion cycle may be referred to as FAS type. FAS type insertion cycles are used to reduce cycle time. FAS type insertion cycles are particularly useful for tools and insertion cycles where the selected required fastening speed is a fraction of the maximum speed achievable by the tool. For example, if the required fastening speed is 100 mm / s but the tool can reach a motion speed of 400 mm / s, an FAS type insertion cycle can be used to reduce cycle time.

[0066] The actual speed advance 206, rivet insertion 208, retract acceleration 210, actual speed retract 212, and retract deceleration 214 phases of the FAS-type cycle shown in Figure 2B are equivalent to the correspondingly named and numbered phases in Figure 2A. The modified advance acceleration phase 200 and the additional phases of fly-across space (FAS) 202 and FAS deceleration 204 are described below.

[0067] Forward Acceleration 200. The setter starts in the initial position as described above. The motor 10 is commanded to accelerate the tool 2 towards the workpiece at a given FAS speed.

[0068] FAS202. Once the FAS speed is reached, the motor torque is reduced to a value that will maintain the setter at the FAS speed. The FAS speed is faster than the required set speed. The torque required to maintain the FAS speed during the FAS202 phase may be referred to as the FAS torque. The FAS phase may also be referred to as the fast advance phase. As discussed above regarding motor torque and tool conditions, the required FAS torque may vary depending on the tool conditions.

[0069] FAS Deceleration 204. A velocity change is initiated at a position between the initial position and the workpiece, which decelerates the tool to the required clamping velocity. The torque required to decelerate the tool during the FAS Deceleration 204 phase may be referred to as the FAS Deceleration Torque. As discussed above regarding motor torque and tool conditions, the required FAS Deceleration Torque may vary depending on the tool conditions.

[0070] Other types of insertion cycles are possible, and the compensation methods described herein are not limited to the two illustrated insertion cycle types. For example, rather than the FAS phase 202 where the FAS speed is greater than the required make-up speed, the insertion cycle may have a phase where the setter speed is less than the required make-up speed.

[0071] 2A and 2B, the magnitude of the motor torque and setter speed are not shown to scale. In particular, the motor torque during the acceleration phases (forward acceleration 200, FAS deceleration 204, reverse acceleration 210, reverse deceleration 214) is shown to have a slope. This is for illustrative purposes only; in use, the slope of the motor torque during use is small (i.e., the motor torque is substantially constant during the acceleration phase).

[0072] 2A and 2B, the motor torque required to achieve a given rivet acceleration and / or speed depends at least in part on the condition of the tool. That is, there is a variation in tool performance that depends at least in part on the condition of the tool. Compensation methods can be provided to compensate for this variation. Such compensation methods allow for the provision of a desired speed (e.g., a required fastening speed during actual speed advance 206) regardless of the condition of the tool. Several compensation methods are described herein.

[0073] Figure 3 illustrates an exemplary compensation method 300. The method 300 illustrated in Figure 3 includes measuring a parameter related to a characteristic of the tool in step 302, comparing the measured parameter to a predetermined parameter value in step 304, calculating an adjustment based on the comparison in step 306, and applying the adjustment to the tool in step 309.

[0074] More specifically, using compensation method 300, a parameter related to a characteristic of the tool is measured (302). The measured parameter may be referred to herein as a measured parameter or a first parameter. The measured parameter includes a value representative of the characteristic and may therefore be referred to as a parameter value, a first parameter value, or a measured parameter value. The characteristic related to the measured parameter may be referred to herein as a first characteristic. The first parameter may be representative of the motion of the tool, for example, the speed or torque of a motor, or the speed of a setter on the tool or the speed of a rivet therein.

[0075] The measurement in step 302 is performed when a characteristic related to the actual measured parameter is substantially constant. Measuring when the characteristic is substantially constant can result in a more accurate measurement. A single measurement may be performed during the measurement step, or multiple measurements may be performed during the measurement step. Additionally, further measurement steps may be performed, as described in more detail below. For illustrative purposes, measurement steps 702a-702d, 712a-712d that may be performed are shown in Figures 2A and 2B and are described in more detail below.

[0076] After the measurement in step 302, the actual parameter is compared to a predetermined parameter value in step 304. The comparison in step 304 may include determining a difference between the actual parameter and the predetermined parameter value. The difference between the first parameter and the predetermined parameter is indicative of a condition of the tool, for example, due to losses in the tool. The comparison may determine that the actual parameter is less than the predetermined parameter value. For example, the predetermined parameter value may be a desired make-up speed, and the actual speed may be determined to be less than the desired make-up speed. This comparison therefore represents a non-optimal (e.g., low or warm) condition of the tool. Alternatively, the predetermined parameter value may be an expected speed, and the actual speed may be determined to be less than the expected speed. Again, this comparison represents a non-optimal (e.g., low or warm) condition of the tool.

[0077] After comparing the actual parameter values ​​with the predetermined parameter values ​​in step 304, the method includes calculating adjustments in step 306. The adjustments are based on the comparison in step 304. The calculated adjustments are adjustments to a characteristic of the tool. In particular, the adjustments are configured to compensate for the condition of the tool so that the tool can perform near-optimally despite the sub-optimal conditions. For example, in the above example where the actual speed is less than the required fastening speed or less than the expected speed, an adjustment to the tool may be calculated to increase the setter speed to reach (or approach) the required fastening speed. The adjustment may be to a second characteristic of the tool that is different from the first characteristic. It should be understood that the first and second characteristics are typically interdependent, such as motor torque and setter speed.

[0078] Finally, method 300 includes applying the adjustments determined in step 306 to the tool in step 309. Applying the adjustments in step 309 may include, for example, increasing motor torque and setter speed by providing commands to the data processing system to increase electrical stimulation applied to the motor. Rapid adjustments can be effected by instantaneously changing the torque of the tool.

[0079] The comparison method 300 can be used for speed-based compensation and / or torque-based compensation.

[0080] In speed-based compensation, the tool is accelerated to a speed (e.g., FAS speed or desired fastening speed) and maintained at that speed (e.g., with coast torque). The torque required to achieve and / or maintain the desired speed is measured in a measuring step 302 and used to calculate and apply subsequent adjustments. For example, the actual measured torque can be compared to an expected coast torque. The expected coast torque is the amount of torque expected to accelerate the tool to the desired speed. The expected coast torque can be derived from measurements from previous insertion cycles and / or can be calculated, for example, by theoretical calculations. In speed-based compensation, it is beneficial to perform the measuring step 302 when the speed is substantially constant, for example, during the actual speed advance phase 206 or the FAS phase 202.

[0081] In torque-based compensation, the tool is first accelerated using an applied torque. The applied torque is the torque expected to accelerate the tool to and maintain a specific predetermined speed (e.g., a required fastening speed) using a specific acceleration. Due to losses in the tool, a specific speed may require a greater torque than expected to maintain the specific predetermined speed. With torque-based compensation, the speed achieved and / or maintained by the tool given the applied torque is measured and compared to the predetermined speed, and adjustments can be calculated and made based on the measured speed. For example, it may be determined that a greater torque limit is required to achieve an optimal (e.g., flush) joint. In torque-based compensation, it is beneficial to perform the measuring step 302 when the torque is substantially constant. Because torque is typically substantially within a phase and varies discontinuously between phases, measurements can be taken at any time within a phase.

[0082] A first type of compensation method can be used during a single insertion cycle and is therefore referred to as in-cycle compensation. The method 300 can be used as an in-cycle compensation method, where the measuring step 302 is performed during the first insertion cycle and the adjustment is applied to the tool in the applying step 309 during the same first insertion cycle.

[0083] 4 illustrates the use of an in-cycle compensation method used to achieve speed-based compensation for an exemplary low or medium temperature tool. FIG. 4 illustrates the motor torque and setter speed for an exemplary insertion cycle of a tool using an in-cycle compensation method according to compensation method 300 of FIG.

[0084] The insertion cycle shown in Figure 4 is similar to that shown in Figure 2B, and like features are numbered accordingly. However, in the insertion cycle shown in Figure 4, during the FAS phase 202, the setter speed is less than the desired make-up speed (as opposed to the setter speed being greater than the desired make-up speed).

[0085] 4 has a forward acceleration phase 200 in which the tool accelerates to a measurement speed (which is less than the desired fastening speed), an FAS phase 202 in which the tool is maintained at the measurement speed, an FAS acceleration phase 204 in which the tool accelerates to the desired fastening speed, and an actual speed forward phase 206 in which the tool is maintained at the desired fastening speed. It should be understood that the FAS acceleration phase 204 is equivalent to the FAS deceleration phase described above, but has a negative deceleration rate.

[0086] In a measurement step 302 performed during the FAS phase 202, the torque required to maintain the measurement speed is measured. The measured torque is compared to the predicted torque in a comparison step 304. In the example shown in Figure 4, the comparison determines that the torque required to maintain the measurement speed was greater than expected, and therefore the final setter speed needs to be increased to compensate for the effects of losses in the tool (e.g., friction losses).

[0087] Therefore, an adjustment is calculated and applied, specifically the acceleration provided to the tool by the motor 10 during the FAS acceleration phase 204. This acceleration results in higher torque and therefore higher setter speed.

[0088] Ideally (i.e., with well-calculated and applied adjustments), the setter speed during the actual speed advance phase 206 is substantially equal to the desired fastening speed. The adjustments applied in step 309 may be greater than or less than the desired fastening speed, referred to as an overshoot or undershoot, respectively. An overshoot 310 can be seen in Figure 4, where the tool is accelerated to a speed slightly greater than the desired fastening speed. Methods for reducing the effects of overshoot and / or undershoot by controlling the change in fastening speed are described in more detail below.

[0089] The compensation methods described herein can be particularly useful when used to calibrate tools, such as low- or medium-temperature tools. Such calibration can compensate for tools having non-optimal conditions and help achieve a set speed that will result in the required rivet insertion force for a given insertion cycle despite the non-optimal tool conditions. Thus, changes in tool force and energy due to internal losses are compensated for using a compensation method that adjusts for the tool's mechanical inertia with speed changes.

[0090] 5 illustrates another exemplary compensation method. In particular, this compensation method can be used for calibration and may be referred to as calibration compensation or calibration. The compensation method 500 includes measuring parameters related to characteristics of the tool 2 in step 502, comparing the measured parameters to predetermined parameter values ​​in step 504, calculating adjustments based on the comparison in step 506, determining the state of the tool in step 507, and determining whether to perform calibration compensation in step 508. If it is determined in step 508 that calibration is to be performed, the method 500 applies the adjustments to the tool 2 in step 509. If it is determined in step 508 that calibration is not to be performed, the process returns to step 502. The determination in step 508 is used to determine whether the tool 2 is in a state requiring calibration compensation, and if calibration is required, the adjustments calculated in step 506 are applied in step 509.

[0091] The determination in step 508 may include determining whether the tool 2 is cold, medium, or hot. Such a determination may be referred to as a condition determination. The condition determination may be performed by measuring the temperature of the tool 2. For example, a temperature measurement means (not shown) may be provided on the tool 2, and the data processing system may receive or acquire the temperature from the temperature measurement means. Alternatively or additionally, the condition determination may be performed by measuring, calculating, or receiving the time since the last insertion cycle of the tool 2. Additionally or alternatively, the condition determination may use the comparison performed in step 504, i.e., based on comparing the measured parameter with a predetermined parameter value. As will be apparent to one skilled in the art, other condition determinations are also possible, such as those related to the overall age of the tool 2.

[0092] If the determined condition meets the predetermined criteria, processing may move from step 508 to step 509. The determination in step 508 may compare the condition determined in step 507 to a predetermined optimum condition threshold. For example, the predetermined optimum condition threshold may be selected to be a predetermined time, such as 15 minutes. Thereafter, if the time since the last insertion cycle was performed exceeds the predetermined time, such as 15 minutes, it may be determined that the tool is "cold" or "warm" and calibration is desired.

[0093] The determining step 507 is shown as occurring after the measurements in step 502, the comparison in step 504, and the calculation of the adjustments in step 506. However, the determining in step 507 may occur at any other point in the process. For example, it may be beneficial to determine the state of the tool before calculating the adjustments, e.g., to reduce the computational load on the data processing system.

[0094] The compensation method described above can be performed during normal operation of the tool 2 (e.g., while inserting a rivet). The compensation method can also be used to calibrate the tool 2 without a rivet present. For example, one or more “dummy” runs can be performed once the tool is determined to be cold. A dummy run can be performed as a single calibration of the tool 2 before inserting a rivet. Alternatively, multiple dummy runs can be performed, each using the compensation method. When multiple dummy runs are performed, each with a compensation method, the difference between the measured parameter and the predetermined parameter value, and therefore the correction, should typically become smaller with each successive dummy run. A threshold can be selected such that the tool is considered “hot” and ready to insert a rivet if the applied correction is less than the threshold. Using multiple dummy runs allows the tool to be accurately heated and prepared for use based on the measured data.

[0095] Preferably, multiple measurements are taken during a single measurement step (e.g., steps 302, 502). By taking multiple consecutive measurements during a single measurement step, more accurate adjustments can be calculated. Furthermore, by taking multiple measurements during a single measurement step, the effect of errors in the measured parameters (e.g., due to variations in tool performance and / or random errors associated with the measurement means) can be reduced.

[0096] If multiple measurements are taken during a single measurement step, these measurements can be processed to provide a single measured parameter. For example, the measured parameter can include an average of multiple measurements. If multiple measurements are taken during a single measurement step, tolerances may be introduced to ensure stability between subsequent measurements. That is, if a single measurement in a series of measurements is outside a desired range (e.g., a measured speed outside a ±3 mm / s error margin relative to the fastening speed), that single measurement or the entire series of measurements may be omitted from future calculations. Alternatively, if a single measurement in a series of measurements is outside a desired range (e.g., outside a 5% error margin relative to the average coast torque), the series of measurements may be stopped and restarted. In this way, adjustments are calculated using only substantially consistent and / or reliable measurements.

[0097] When multiple measurements are taken, a weight can be assigned to each measurement. The weight can also be referred to as a confidence value. The confidence value represents how closely the measured parameter value matches the theoretical parameter value. Since the approximate relationship between the parameters for a given tool and insertion cycle type can be theoretically known or can be empirically derived based on use cases, a formula can be used to calculate the theoretical value.

[0098] Equation 1 determines the theoretical coast torque value C for a particular tool and a particular insertion cycle type. T An exemplary formula used to calculate ρ is shown below: This equation may be empirically derived, for example, based on use cases.

[0099]

number

[0100] Actual coast torque is theoretical torque C T The confidence value can be ascertained by comparing it to . By measuring the parameter multiple times, a confidence value can be calculated for each measured parameter value. A weighted average can be calculated over the multiple measurements, with each measurement weighted by its corresponding confidence value.

[0101] In some examples, no adjustments are applied unless the confidence value of one or more measurements exceeds a predetermined confidence threshold, hi other examples, the adjustments may be weighted based on the magnitude of one or more of the confidence thresholds.

[0102] In some cases, it may be beneficial to perform the maximum number of measurements within a phase of the insertion cycle, such as the actual speed advance phase 206. For example, for an actual speed advance phase 206 with a duration of 2.5 seconds and a duration of 25 ms per measurement, 100 measurements may be performed during the actual speed advance phase. In this manner, measurements may be performed during the actual speed advance phase 206 without a time penalty. The greater the number of measurements, the more accurate adjustments may be calculated. Alternatively, it may be beneficial to reduce the number of measurements below the maximum number. For example, reducing the number of measurements may be advantageous in reducing computational requirements and / or allowing measurements to be stopped and restarted in the event of instability. It has been found that a measurement step including six or more measurements provides sufficient data to calculate and apply more effective adjustments than a single measurement. However, any number of measurements may be performed, such as 1, 20, or 200.

[0103] In the exemplary method described above with reference to Figures 3-5, an adjustment is calculated based on measurements made during the current insertion cycle and the adjustment is applied to the current insertion cycle, i.e., the adjustment is applied to the same insertion cycle in which the parameter was measured.

[0104] 6 shows another exemplary compensation method 600 in which an adjustment is applied to a different insertion cycle than the one in which the parameter was measured. Method 600 includes measuring a parameter related to a characteristic of tool 2 in a first insertion cycle X in step 602, comparing the measured parameter to a predetermined parameter value in step 604, calculating an adjustment based on the comparison in step 606, storing the adjustment in, for example, a servo controller memory in step 607, and applying the adjustment to the tool during a second insertion cycle Y in 609. The same adjustment may be applied in a single second insertion cycle, or may be applied in multiple insertion cycles, for example, the next 20 cycles, or for a specific period of time, for example, the next 30 minutes.

[0105] Method 600 may further include measuring two or more parameters in measuring step 602. For example, as shown as an optional step of method 600 in Figure 6, the first measurement in step 602 may further include measuring a first parameter related to a characteristic of tool 2 in step 602a and measuring a second parameter related to the characteristic of tool 2 in step 602b. The first and second parameters may relate to the same characteristic of tool 2. Method 600 is not limited to two parameters and any number of measurements may be performed.

[0106] In Figure 6, measurements are made in a first insertion cycle X and applied during a second measurement cycle Y. Measurements may also be made in a second insertion cycle Y. Such measurements made in the second insertion cycle Y may then be compared to measurements made in the first insertion cycle X and / or predetermined values ​​to calculate an adjustment.

[0107] 7 shows another exemplary compensation method 700 in which measurements are taken during both a first insertion cycle X and a second insertion cycle Y. Method 700 includes, during a first insertion cycle X, measuring a first parameter associated with a characteristic of tool 2 in step 702a, performing a lookup to return an expected value of the first parameter in step 704, measuring a second parameter in step 702b, calculating an adjustment based on a comparison of the second parameter with the expected value in step 706, and applying the calculated adjustment during the first insertion cycle X in step 709.

[0108] Step 702b of measuring the second parameter, step 706 of calculating the adjustment based on a comparison of the second parameter with an expected value, and step 709 of applying the adjustment may be repeated multiple times while the system is at constant speed, for example, during actual speed advance phase 206. That is, the ability to make multiple measurements, calculations, and therefore corrections, during such a phase allows for greater control of the compensation applied to the tool. Thus, if a first adjustment leads to over-correction (e.g., using the example cycle shown in FIG. 4, the speed is greater than the required tightening speed), then one or more subsequent adjustments may be applied to further correct the parameter (e.g., reduce the speed to the required tightening speed).

[0109] Upon completion of the first insertion cycle X, one or more measured parameters and / or calculated adjustment values ​​may be stored in a lookup table (i.e., the lookup table accessed during step 704 of compensation method 700). The updated lookup table is subsequently accessed during lookup step 714 of compensation method 711 of the second insertion cycle Y.

[0110] The compensation method 711 for the second insertion cycle Y can be considered generally equivalent to the compensation method 700 for the first insertion cycle X, and includes measuring a first parameter related to a characteristic of the tool in step 712a, performing a lookup to return a predicted value of the first parameter in step 714, measuring a second parameter in step 712b, calculating an adjustment based on a comparison of the second parameter with the predicted value in step 716, and applying the calculated adjustment during the second insertion cycle Y in step 719. Upon completion of the second insertion cycle Y, one or more measured parameters and / or the calculated adjustment may be stored in a lookup table (i.e., the lookup table accessed during step 714 of the compensation method 711). The updated lookup table is then accessed during subsequent cycles.

[0111] Thus, each insertion cycle can provide measurements that can be stored and used in calculating adjustments in future insertion cycles, forming a feedback loop. That is, parameters measured and stored in a previous insertion cycle can be considered as predetermined values ​​that can be compared to parameters measured in a current or future insertion cycle. For example, actual measurements can be compared to expected values ​​that are considered as predetermined values. The stored values ​​(i.e., stored parameters) can be used to monitor (and adjust) the condition of the tool based on previous values ​​associated with the tool based on said comparison. The stored values ​​can also be returned and used in calculating adjustments.

[0112] Two insertion cycles X, Y are shown in Figure 7. However, it should be understood that additional insertion cycles may occur before or after the illustrated insertion cycles X, Y. Thus, stored values ​​may contribute to the comparison and / or calculation steps in the next insertion cycle. Correspondingly, stored values ​​from a previous (but not shown) insertion cycle may contribute to the comparison and / or calculation steps 704, 706 in insertion cycle X. These processes are indicated by the dotted arrows in Figure 7.

[0113] Calculating adjustments in such a feedback loop beneficially reduces the effects of overshoot (as discussed above with reference to Figure 4). Advantageously, by sampling data from previous insertion periods, more accurate and reliable adjustments can be applied.

[0114] The use of the above methods 700, 711 will now be described with reference to the insertion cycle shown in Figures 2A and 2B.

[0115] 2A illustrates an exemplary scheme for taking measurements during an insertion cycle. In particular, the scheme for taking measurements includes the method 700 described above, which includes two measurement steps 702a, 702b. FIG. 2A shows measurement step 702a, which includes one measurement taken during the forward acceleration phase 200, and another measurement step 702b, which includes multiple measurements taken during the actual speed forward phase 206.

[0116] The parameters measured in the first and second measurement steps 702a and 702b are the acceleration torque A M and coast torque C M It is useful to know the acceleration torque A M During the forward acceleration phase 200, where M What is useful is that the coast torque C M During the actual speed forward phase 206, where is substantially constant, the coast torque C M The second measurement step 702b is to measure the coast torque C M eight times, i.e., eight individual measurements. To realize the above-described advantages of taking multiple measurements in a single measurement step, the stabilization and averaging processes described above with respect to taking multiple measurements are performed.

[0117] 2A may be performed during a first insertion cycle X. The parameters measured during the first and second measurement steps 702a, 702b of the first insertion cycle X may be referred to as first and second measured parameters, respectively.

[0118] An additional insertion cycle may also be performed, e.g., a second insertion cycle Y. The second insertion cycle Y is not shown in FIG. 2A but may be considered substantially equivalent to the first insertion cycle X. During the second insertion cycle Y, first and second measurement steps 712a, 712b are performed, again measuring the acceleration torque A, respectively. M and coast torque C M The parameters measured in the first and second measurement steps 712a, 712b of the second insertion cycle Y may be referred to as a third parameter and a fourth parameter. The first and third parameters are the acceleration torque A M The second and fourth parameters are the coast torque C M The actual acceleration torque A measured during the insertion cycle M is the corresponding coast torque C measured during the same insertion cycle. M It has.

[0119] The methods 700, 711 include storage steps 710, 710. That is, the first, second, third, and / or fourth parameters may be stored. For example, they may be stored in a computer storage device associated with the tool 2. The acceleration torque A M and coast torque C M may be stored in a table, for example a lookup table, although it will be appreciated that any suitable data structure may be used. The stored data may then be used in further insertion cycles, for example returned in the lookup step, and used to calculate the adjustment.

[0120] 2B shows an exemplary scheme for taking measurements during another insertion cycle, particularly a FAS-type insertion cycle. The measurement scheme is similar to that described above with reference to method 700, but includes additional measurement steps. FIG. 2B shows a first measurement step 702a including a single measurement taken during the forward acceleration phase 200, a second measurement step 702b including multiple measurements taken during the FAS phase 202, a third measurement step 702c including a single measurement taken during the FAS deceleration phase 204, and a fourth measurement step 702d including multiple measurements taken during the actual speed forward phase 206.

[0121] The parameters measured in the first, second, third, and fourth measurement steps 702a, 702b, 702c, 702d are acceleration torque, FAS torque, FAS deceleration torque, and coast torque. Beneficially, acceleration torque and FAS deceleration torque are measured during the forward acceleration phase 200 and the FAS deceleration phase 204, respectively, when torque is substantially constant. Beneficially, FAS torque and coast torque are measured during the FAS phase 202 and the actual speed forward phase 206, respectively, when torque is substantially constant. The second measurement step 702b includes measuring FAS torque three times, i.e., taking three separate measurements. The fourth measurement step 702d includes measuring coast torque four times, i.e., taking four separate measurements. To realize the above-described advantages of taking multiple measurements in a single measurement step, the stabilization and averaging processes described above with respect to taking multiple measurements are performed.

[0122] The measurements shown with respect to Figure 2B may be made during a first insertion cycle X. The parameters measured during the first, second, third, and Figure 4 measurement steps 702a, 702b, 702c, 702d of the first insertion cycle X may be referred to as first, second, third, and fourth measurement parameters, respectively.

[0123] Additional insertion cycles may be performed, such as a second insertion cycle Y. The second insertion cycle Y is not shown in FIG. 2B but may be considered to be substantially equivalent to the first insertion cycle X. During the second insertion cycle Y, first, second, third, and fourth measurement steps 712a, 712b, 712c, and 712d may be performed. The parameters measured in the measurement steps 712a, 712b, 712c, and 712d of the second insertion cycle Y may be referred to as the fifth, sixth, seventh, and eighth parameters.

[0124] The methods 700, 711 include storing steps 710, 720. That is, the first, second, third, fourth, fourth, sixth, seventh, and / or eighth parameters may be stored. For example, they may be stored in computer storage associated with the tool 2. The parameters may be stored in a table, for example, a look-up table, although it will be appreciated that any suitable data structure may be used. The stored data may then be used in further insertion cycles, for example, returned in the look-up step and used to calculate adjustments.

[0125] FIG. 8 illustrates an exemplary table 800 that can be used to store parameter values. In particular, the exemplary table 800 stores first, second, third, and fourth parameters, although it should be understood that similar tables may be used to store different parameters. The tables are associated with specific characteristics 802 of the tool and / or insertion cycle, such as tool number, rivet setting speed, acceleration, insertion cycle type, etc. Thus, there may be multiple other tables (i.e., collections of tables) similar in form to the exemplary table 800 but storing different data depending on the specific characteristics of the tool. For example, the exemplary table 800 may be associated with a first tool operating at a setting speed of 100 mm / s, while a second table may be associated with a first tool operating at a setting speed of 150 mm / s. Each table may have a table number T.

[0126] In use (i.e., when the tool is performing an insertion cycle, such as the insertion cycle shown in FIG. 2A), during the forward acceleration phase 200, an acceleration torque AM At a particular point during the forward acceleration phase 200, for example when a particular setter speed is reached or the setter has traveled a particular distance, the motor torque is sampled and an acceleration torque value (A M ) is calculated. After the acceleration torque is sampled, the actual acceleration torque A M is entered as an index into a corresponding table (i.e., a table corresponding to a particular characteristic of the tool). The corresponding table may be determined by searching a set of tables. The table determined from the set of tables may be the table that best matches the particular characteristic of the tool compared to other tables in the set of tables.

[0127] 8 provides a method for empirically determining a predicted coast torque from a measured acceleration torque. For example, by storing a previous measured value of a first parameter and a corresponding measured value of a second parameter (i.e., measured during the same insertion cycle), an empirical relationship between the two parameters can be determined. In particular, the example table 800 described herein can be used to determine an empirical relationship between acceleration torque and coast torque. However, depending on the selection of parameters, relationships can be determined between different parameters, such as FAS torque and acceleration torque, coast torque and torque limit, etc.

[0128] Each table contains N columns or "slots" in which data can be stored. Table 800 of FIG. 8 has slots numbered 0 through N-1. A table may have, for example, 64 slots (i.e., N=64). Table 800 of FIG. 8 stores measured parameter values ​​(in this example, the second parameter coast torque C) in data storage locations. M ). Each data location has a slot number corresponding to the column (i.e., slot) in which it is located. Each slot is an integer.

[0129] Each table has two additional memory locations arranged to store a first stored parameter associated with the first slot (i.e., slot number zero (0)) and a first stored parameter associated with the last slot (i.e., slot number (N-1)). In FIG. 8, the first stored parameter is the acceleration torque A associated with the tool given the tool's particular characteristics 802. M The minimum acceleration torque A min Minimum acceleration torque A min 8, the final stored parameters are the acceleration torque A associated with the tool given the specific characteristics 802 of the tool. M The maximum acceleration torque A max Maximum acceleration torque A max may be predicted or may be based on previous actual measurements.

[0130] Therefore, the table 800 is used to calculate the second parameter (i.e., the coast torque C M ) and the value of the first parameter (i.e., acceleration torque A M The minimum and maximum coast torque values ​​C are stored. M are sequenced so that they can be used and recalled when needed. M The slot number corresponds to each coast torque value C M and assign a coast torque value C to that slot. M The slot number is ordered by storing the coast torque value C M The acceleration torque value A related to (i.e. measured in the same insertion cycle) M , and acceleration torque value A M and the maximum and minimum acceleration torque values ​​A stored in table 800. max , A min In FIG. 8, a table 800 is provided for the initial acceleration torque A min Coast torque value C related to M From the above, the maximum acceleration torque A of slot N-1 max Coast torque value C related to Mcan be ordered up to

[0131] Table 800 may be used in a storage process (e.g., storage steps 710, 720). Table 800 may also be used in a lookup process (e.g., lookup steps 704, 714) in which a value may be selected from table 800. In the lookup process, the selected value is output from table 800 and may be used in a calculation step (e.g., calculation steps 706, 716). Because values ​​are returned as output from table 800, the lookup steps or processes, e.g., lookup steps 704, 714, may be referred to as return processes or table returns.

[0132] 2A and 2B, many measurements can be taken throughout the rivet cycle, for example, in measurement steps 702, 702b, up until the point where the rivet contacts the workpiece. The actual measurements can then be used to calculate and apply adjustments to the tool characteristics. Using the initial measurement made in measurement step 702a during the initial acceleration phase 200, a lookup process generates a predicted coast torque value, and measurements made in measurement step 702b during the actual speed advance phase 206 are compared to the predicted coast torque value. Adjustments are calculated based on the comparison.

[0133] The storage and lookup process is described in more detail below.

[0134] Table Memory Table 800 may initially be empty (i.e., table 800 may hold no values). Alternatively, table 800 may be populated with predetermined values, such as the expected coast torque C from similar tools and / or calculations. M For each new insertion cycle, for example the first insertion cycle Y, new measured parameter values ​​are entered into the table.

[0135] The first parameter (i.e., the acceleration torque value A M) is assigned a slot number when it is measured, for example, in measurement step 702a of insertion cycle Y. The slot number is M The maximum and / or minimum acceleration torque A of the table max , A min For example, Equation 2 below can be calculated by comparing the measured acceleration torque value A M and the previously measured minimum and maximum acceleration torque A min , A max to determine the closest slot number. The slot number is denoted using the integer value S. The addition of 0.5 in equation 2 before taking the integer value (the "INT" operation) ensures that the calculation chooses the closest integer for floating point calculations.

[0136]

number

[0137] If Equation 2 calculates an integer value S in the range zero (0) to (N-1), the measured acceleration torque A M is assigned a slot number equal to the integer value S.

[0138] If the slot number is outside the range 0 to (N-1), the data table range is adjusted.

[0139] If the calculated integer value S is less than zero (0), the actual acceleration torque A M The previous measured minimum acceleration torque A min Therefore, if the calculated integer value is less than or equal to zero (0), the actual acceleration torque A M is assigned a slot number equal to zero (0). M is the previously stored minimum acceleration torque A min is stored in the table 800 so as to overwrite the minimum acceleration torque A min is the measured acceleration torque A M (The stored minimum acceleration torque A min The actual acceleration torque A MInstead of simply overwriting with the offset, use equation 3 to calculate the minimum acceleration torque A min The offset is the actual acceleration torque A M This is a small value compared to the minimum acceleration torque A min This prevents repeated recalculation of slot numbers when there is only a small change in

[0140]

number

[0141] For example, if the acceleration torque limit is 100%-150%, a 5% offset is used, and the measured torque is 95%, the limit will be changed to 90%-150%.

[0142] If the calculated integer value S is greater than (N-1), the actual acceleration torque A M The previous measured maximum acceleration torque A max Therefore, if the calculated integer value is greater than or equal to (N-1), the actual acceleration torque A M is assigned a slot number equal to (N-1). M is the previously stored maximum acceleration torque A max is stored in the table 800 so as to overwrite the maximum acceleration torque A max is the measured acceleration torque A M (The maximum acceleration torque A is set equal to the stored maximum acceleration torque A.) max The actual acceleration torque A M Instead of simply overwriting it with the offset, use equation 4 to calculate the maximum acceleration torque A max The offset is the actual acceleration torque A M This is a small value compared to the maximum acceleration torque A max This prevents repeated recalculation of slot numbers when there is only a small change in

[0143]

number

[0144] Minimum and / or maximum acceleration torque A min , A max After recalculation of (N), the slot number S is calculated based on the new acceleration torque range. Any value stored in slots 1 to N-1 can be subsequently shifted to a higher or lower value slot, for example, to account for the change.

[0145] Thereafter, in measurement step 702b of, for example, insertion cycle X, the second parameter (i.e., coast torque C M ) is measured, the actual acceleration torque A M For example, if the slot number S determined using Equation 2 is S=15, then the measured second parameter is also assigned slot number S=15.

[0146] If the determined slot (e.g., slot number S=15) of the table 800 is empty, the coast torque C M is inserted unchanged into the empty slot. If a value, e.g., a previous measured value or an initialized predetermined value, already exists in the slot, that value may be overwritten, e.g., to maintain an up-to-date table of values, or a new value, e.g., calculated based on the previous actual measured value and / or the initialized predetermined value and the new actual measured value, may be calculated and inserted into the determined slot.

[0147] This process generates measured coast torque values ​​C associated with a tool having particular characteristics 802 for multiple iterations of a particular insertion cycle type. M Each time an insertion cycle is performed, the acceleration torque A M is measured, the slot number is calculated, and the coast torque C M is measured, and the coast torque C M(or a value calculated based thereon) is added to the calculated slot number in table 800. For example, if the calculated slot number is 56, then the coast torque C M is added to slot 56 of table 800. Table 1 therefore contains a sequence of ordered coast torque values ​​C measured during the previous insertion cycle. M It will show:

[0148] It should be noted that a tool may perform an insertion cycle for which no corresponding table exists (e.g., if there is no table associated with the particular characteristics of the tool and insertion cycle). If a table does not exist, a new table may be created. One or more of the slots in the new table may be empty or may be initialized with predetermined values. For example, the new table may contain the estimated maximum and / or minimum acceleration torque A max , A min The estimated maximum and / or minimum acceleration torque A max , A min is the maximum and / or minimum torque A of an existing table with certain characteristics similar to those associated with the new table. max , A min Alternatively, the estimated maximum and / or minimum acceleration torque A max , A min is the measured acceleration torque (A M ) can be calculated based on the offset from

[0149] Furthermore, it should be noted that the values ​​stored in table 800 may be stored in their original form or may be stored after processing (eg, normalization).

[0150] Table Return For example, after input using the method described above, table 800 contains a sequence of ordered coast torque values ​​C measured during previous insertion cycles. MThus, a value from table 800 can be returned and used in a comparison of the actual value with the returned value, which can then be used to calculate the adjustment. The return process is described herein with reference to the second insertion cycle Y, e.g., as described with reference to Figures 2A, 7, and 8.

[0151] The third parameter (i.e., acceleration torque A M ) is assigned a slot number when it is measured, for example, in measurement step 712a of insertion cycle Y. The slot number is M The maximum and / or minimum acceleration torque A stored in the corresponding table 800 max , A min For example, using Equation 2, the slot number can be determined by the integer value S:

[0152] Based on the assigned slot number, for example, in lookup step 714, table 800 calculates the expected coast torque C E is returned as output to the return process. The predicted coast torque C E contains a coast torque value stored in a slot of table 800 or a value derived therefrom, i.e., the predicted coast torque C E The slot number for the actual acceleration torque A measured during measurement step 712a M (i.e., the third parameter) is between the lower and upper limits (i.e., the maximum and minimum acceleration torque A max , A min The predicted coast torque (C E ) can be returned from table 800 using equation 5.

[0153]

number

[0154] If the slot number S is calculated to be within the range zero (0) to (N-1), the actual acceleration torque A Mis assigned a slot number equal to the integer value S, and the coast torque stored in that slot is returned accordingly.

[0155] If the expected coast torque value is zero or another null value, it indicates that no data is present in that slot. For example, this may indicate that a sufficiently similar insertion cycle has not been performed. In this case, the expected coast torque C E However, other stored coast torque values ​​C may be used in this table 800 or in another table related to a similar specific characteristic. M The predicted coast torque C can be calculated based on the E can be calculated using the coast torque formula derived for a particular tool assembly using Equation 6.

[0156]

number

[0157] If the slot number S is calculated to be outside the range of zero (0) to (N-1), the table is changed to accommodate the new limits (as described above with respect to table storage). E can subsequently be estimated.

[0158] If the slot number S is calculated to be less than zero (0), this means that the actual acceleration torque A M The previous measured minimum acceleration torque A min Therefore, if the integer value is less than zero (0), the stored coast torque value C M is the predicted coast torque C E Alternatively, the stored coast torque value C for slot zero (0) can be returned as M Based on the calculation including the expected coast torque C E For example, the calculation may return the stored coast torque value C for slot zero (0). M minus an offset, which may be weighted based on the magnitude of the calculated integer value S.

[0159] Correspondingly, if the slot number S is calculated to be greater than (N-1), this means that the measured acceleration torque A M The previous measured maximum acceleration torque A max Therefore, if the integer value is greater than (N-1), the stored coast torque value C for slot (N-1) M is the predicted coast torque C E Alternatively, the stored coast torque value C for slot (N-1) can be returned as M Based on the calculation including the expected coast torque C E For example, the calculation may return the stored coast torque value C for slot (N-1). M plus an offset, which may be weighted based on the magnitude of the calculated integer value S.

[0160] Returned expected coast torque C E may be returned in stored form, or may be further processed before (or as part of) being returned. For example, if the value was normalized before storage, it may be denormalized before being returned. Additionally or alternatively, the coast torque value may be interpolated with values ​​from adjacent slots.

[0161] Estimated coast torque C E After is returned from table 800, it can be used to calculate the adjustment (e.g., in step 716). In step 712b, a fourth parameter is measured. In this example, the fourth parameter is coast torque C M Measured coast torque C M and the expected coast torque C returned in the lookup step E The difference between this and the actual coast torque C indicates the tool condition at the time of measurement. M is the predicted coast torque C E The difference between the measured coast torque C and the actual coast torque C can be used to determine the amount of compensation required during a particular fastener driving cycle. Mand predicted coast torque C E Based on the difference between

[0162] The adjustment may include, for example, increasing the coast torque to a value that more closely matches the desired coast torque by providing a command to the data processing system to increase the electrical stimulus applied to the motor. E and the desired coast torque. The calculated adjustments can then be applied to the tool (e.g., in step 719). The adjustments can be adjusted electrical impulses provided to the motor. In this manner, adjustments can be calculated and applied in the current insertion cycle using parameters measured in the previous insertion cycle. Beneficially, this allows the tool to compensate for losses based on data collected in previous similar insertion cycles, leading to effective and accurate adjustments.

[0163] Preferably, the acceleration torque A measured in the measuring step 712a M and the actual coast torque C measured in measurement step 712b M are also stored in the table so that they can be used in future insert cycles (e.g., to sort and / or return table 800).

[0164] This type of comparison method may function in a "measurement only" mode (i.e., values ​​are measured each cycle and stored in a table), or alternatively, in an "adjustment only" mode (i.e., adjustments are applied based on previously stored values, but new measurements are not stored).

[0165] Alternatively, both measurements and adjustments are used in a single cycle. That is, measurements are made and stored in multiple first cycles. These measurements are used in a first cycle to calculate and apply adjustments in the first cycle, and are also stored for use in a second cycle to calculate and apply adjustments in the second cycle. Similarly, measurements made in a second cycle can be used in a second cycle to apply adjustments in the second cycle, and are also stored for use in another cycle to calculate and apply adjustments in another cycle. This type of comparison method is beneficial in providing a constant feedback system that compensates for losses based on actual measurements.

[0166] 9 illustrates a method that can be used to improve the reliability of the measurements, and thereby the reliability of the calculated adjustments. This method can be used to increase the reliability of the sampled measurements, particularly when multiple measurements are taken in a single measurement step. In particular, FIG. 9 illustrates a portion of an insertion cycle in which a first measurement step 702a, 712a, including a single measurement, is performed during the forward acceleration phase 200, and a second measurement step 702b, 712b, including multiple measurements, is performed during the actual speed forward phase 206.

[0167] Using the individual measurements of the second measurement steps 702b, 712b as samples, the coast torque C during different times / distances within the actual speed advance phase 206 is calculated. M is sampled. After each measurement in the second measurement steps 702b, 712b, a sampling enhancement is performed.

[0168] A confidence level is assigned to each measurement in the second measurement steps 702b, 712b. A higher confidence level is assigned to a particular measurement if there is a high correlation between the expected coast torque (e.g., returned from table 800) and a particular measured coast torque value. Alternatively or additionally, a higher confidence level may be assigned to a particular measurement if there is a high correlation between a previous measured torque value (e.g., a coast torque value previously measured in the second measurement steps 702b, 712b) and a particular measured coast torque value. Alternatively or additionally, a newer (i.e., more recent) measurement may be assigned a higher confidence level compared to an older measurement, e.g., a measurement from a previous insertion cycle.

[0169] Weighted average coast torque C MA is calculated from the weighted average of all coast torque data sampled in the second measurement steps 702b, 712b. The weighted average coast torque C MA is updated after each measurement in the second measurement steps 702b, 712b. Each measurement is weighted based on its confidence value and the confidence value of each subsequent coast torque measurement. The weighted average coast torque C MA can be calculated using Equation 7.

[0170]

number

[0171] Estimated coast torque C E The average coast torque C MA and compared to the actual coast torque for each sample, losses in the tool (e.g., due to setter conditions) can be estimated. Such estimates can be used to modify the coast torque applied to the tool during the actual speed advance phase 206. For example, the coast torque can be calculated using Equation 8 by subtracting the initial coast torque C I (i.e., the coast torque value measured in the sampling step) to update the clamp limit C UK is a compensation coefficient, which can be in the range of 1 to 1.25, for example.

[0172]

number

[0173] Due to the way the clamp torque is applied, there is a negligible delay between measuring the torque and applying an adjustment to the torque, so compensation can be performed within the same insertion cycle.

[0174] This process can be run multiple times to iteratively improve the torque. For example, in FIG. 9, the process is run eight times so that the coast torque is adjusted eight times, ultimately resulting in a final coast torque C F Final coast torque C F has a higher confidence value than the previous coast torque value due to multiple adjustments made, i.e., the final coast torque is closer to the expected coast torque than the initial measured coast torque due to sampling refinement performed.

[0175] Thereafter, the previously measured acceleration torque A measured in the first measurement step 702a is M Based on the average coast torque C MA may be inserted into the assigned slot number in a table (eg, table 800).

[0176] At the end of the riveting cycle, this final calculated average coast torque C MA is stored in the torque table at the slot position previously calculated. If the slot is already at the coast torque value C M If it contains, the average coast torque C MA can be slotted by a simple N-point moving average nRA. The n-point moving average can be expressed as Equation 9 with a mean value n (which can be, for example, 8):

[0177]

number

[0178] Variations of the above sampling enhancements may be used, which may include intelligently smoothed moving averages as described below, and are provided to improve the reliability of the sampled data and minimize sampling error.

[0179] 10 illustrates an exemplary compensation method 1000. The exemplary compensation method incorporates many of the methods and processes described above.

[0180] In a first step 1001, a new torque reading (ie, acceleration torque) is measured during the forward acceleration phase.

[0181] In a second step 1002, a determination is made as to whether a table exists that corresponds to the current tool and insertion cycle (eg, current tool type, required insertion speed (velocity), and acceleration).

[0182] If it is determined in the second step 1002 that a table exists, the data slots of the table are calculated in a third step 1003. The data slots, for example the slot number S, can be calculated as described above.

[0183] In a fourth step 1004, a determination is made as to whether there is data stored in the calculated data slot. For example, data may have been stored during a previous insertion cycle.

[0184] If the data is present, then in a fifth step 1005, the data is returned from the table as the predicted coast torque value.

[0185] If the second step 1002 determines that a table does not exist, the method skips to a sixth step 1006. In the sixth step 1006, a predicted torque value, which may be based on a predicted torque equation, for example, Equation 6, is returned.

[0186] In a seventh step 1007, a new torque reading (ie, coast torque) is measured during the actual speed forward phase.

[0187] In an eighth step 1008, the new torque reading is compared to the expected coast torque. The comparison is used to generate an adjustment to the coast torque to compensate for losses in the tool. That is, the adjustment is the calculated compensation to be applied.

[0188] In a ninth step 1009, the compensation is applied to the tool.

[0189] In a tenth step 1010, a determination is made as to whether insertion (i.e., inserting the fastener into the workpiece) is complete. This determination can be made based on time, setter, and / or rivet location measurements, or any other method.

[0190] If the insertion is incomplete, the seventh to tenth steps 1007 to 1010 are repeated. By repeating these method steps 1007 to 1010, the tool can be compensated iteratively, thereby making the overall compensation more accurate.

[0191] If the insertion is complete, the method proceeds to an eleventh step 1011 .

[0192] In an eleventh step 1011, a determination is made as to whether the table is in use. The determination may be invoked from the second step 1002.

[0193] If the table is in use, the predicted torque values ​​in the table are updated with the new measured coast torque values ​​in a twelfth step 1012. As described above, the new measured coast torque values ​​may overwrite the previous predicted torque values, or new values ​​may be generated and inserted into the table based on the new and previous values, for example using nRA.

[0194] If it is determined in step 1011 that no tables are in use, the method proceeds to step 1013 where a determination is made as to whether or not free tables are available. That is, depending on the storage capacity of the computer storing the tables, a certain number of tables may be in use.

[0195] If an empty table is available, then in a fourteenth step 1014 a new table is created with the new measured coast torque value inserted.

[0196] If no free tables are available, the process ends at 1016. The absence of free tables may indicate that enough data has been added and that no more data is needed at this stage. Alternatively, it may indicate that more storage is needed.

[0197] After storing the value in the table, for example in the twelfth or fourteenth steps 1012, 1014, the process also ends at 1016. At this point, the value can be returned in a future insertion cycle, for example during the fifth step 1005 where the predicted torque value is returned from the table in another insertion cycle.

[0198] 11a and 11b show exemplary data from an actual tool using the method 1000 described herein.

[0199] The effect of the compensation method 1000 is shown in Figures 11A and 11B. Figure 11A shows data from a known tool without the compensation method. Figure 11B shows data from a similar tool using the compensation method 1000 as described above. The data show measured coast torque and end position values ​​on the same scale as the tool warms up. The end position can be used as a measure of the tool's control accuracy. In an ideal process, the end position of the first cycle should match the end position of the next cycle regardless of the tool condition. Variations in end position can indicate changes in clamping force / energy without losses being effectively compensated for.

[0200] 11A and 11B show that without the compensation method, the end position can vary by approximately 0.8 mm during tool warm-up. Using the compensation method described herein, this variation is reduced to 0.05 mm. This reduction in end position variation indicates that losses have been significantly compensated.

[0201] Intelligently smoothed moving average Smoothing can also be used to improve the reliability of the measurements and therefore the reliability and accuracy of the adjustment. Smoothing is particularly useful when multiple measurements are taken in a single measurement step, such as in the second measurement steps 702b, 712b described above. As each measurement is taken, a moving average (weighted or unweighted) can be determined and the average can be smoothed as described below.

[0202] After a step change in a parameter occurs, for example due to a change in the fastener driving phase, such as a discontinuous torque change between the forward acceleration and actual speed forward phase, the smoothed moving average sRA is typically reset. When reset, the count number M is reset to 1. The count M is then updated every time a new measurement J is made. M is performed. The count M is incremented from 1 to the desired smoothing factor F (F is the smoothing period, which may be, for example, 24). The smoothed moving average sRA is calculated by multiplying the previous moving average sRAM using Equations 10 and 11. M-1 From each measurement J MThe updated moving average sRA after M is iteratively updated to

[0203]

number

[0204] 12 shows data from an actual tool running a FAS type insertion cycle. In particular, smoothed torque data 120 is shown compared to raw data 122 and a simple moving average 124. Setter speed 126 is also shown for reference.

[0205] Further improvements in sampling and / or smoothing can be particularly useful to reduce the effects of periodic changes in parameter values. For example, due to the periodicity of the motor, measured torque data typically varies periodically depending on where in the motor rotation cycle the measurement is performed. Sampling from such oscillatory data can introduce sampling errors. This oscillation is particularly evident at low setter speeds, e.g., below 200 mm / s.

[0206] The variability of the measured torque data can be seen in Figures 12 and 13. Figure 13 shows data from an actual tool running a FAS-type insertion cycle with a different motor oscillation period and setter speed than that shown in Figure 12. In particular, the oscillation period and setter speed are such that the measured torque oscillates for approximately 5 mm of setter travel, which corresponds to the distance traveled per motor and tool revolution with a 5 mm roller screw lead and a 1:1 gear ratio between the tool and motor. It can be seen that the oscillations are evident in both the raw data 132 and the smoothed moving average data 130. The setter speed 136 is also shown for reference.

[0207] To calculate a more stable reading, an intelligent smoothed moving average process can be used. In particular, the smoothed moving average is calculated depending on the motor revolution. The averaging can be a simple numerical sum of the motor torque measurements that occur within a particular motor revolution divided by the number of measurements made within the motor revolution.

[0208] In the first example shown in Figure 13, measurements within a particular motor revolution are averaged at the same point in time during the motor revolution. In this case, measurements are averaged per motor revolution, taking into account all measurements made during that motor revolution.

[0209] That is, measurements are averaged every 5 mm of setter travel (assuming a roller screw lead of 5 mm and a 1:1 gear ratio between the tool and the motor). Averaged samples 138 calculated every 5 mm of setter travel are shown in Figure 13. It can be seen that this intelligent smoothed moving average method reduces jitter in the averaged measurements compared to both the raw data 132 and the simple smoothed moving average data 130.

[0210] The number of measurements performed during each revolution can vary depending on the achievable measurement rate and / or instantaneous tool speed. Measurement rates of 15 to 50 measurements per motor revolution can be used. The number of measurements per motor revolution is M rev It can be shown as:

[0211] While the example shown in Figure 13 averages each motor revolution, it should be understood that a similar effect could be achieved by averaging non-consecutive revolutions at the same point in the motor revolution, for example, averaging every other revolution.

[0212] In an alternative averaging method, a fraction f of a motor revolution is chosen and measurements are summed after the motor has rotated that fraction f of a revolution, i.e., f × M rev The measurements are summed for each measurement. The resulting sum may be referred to as the total partial measurement. f×M rev Each set of measurements may be referred to as a position interval. During one rotation of the motor, 1 / f total partial measurements are produced.

[0213] After the motor has rotated once (and 1 / f partial sum measurements have been generated), the sum of each partial sum measurement is multiplied by the total number of measurements M revAn average measurement is calculated based on the sum of the previous 1 / f total partial measurements. The average is then updated every fraction f of a motor revolution, and may therefore be referred to as an updated average. The updated average is based on the sum of the previous 1 / f total partial measurements. In this way, the average is updated multiple times during one motor revolution (i.e., 1 / f times), thereby providing additional data points compared to averaging only once per revolution. Although each updated average is offset, incorporating measurements from one motor revolution removes jitter and / or vibration. Such additional data points may be able to provide more accurate compensation. For example, additional data points may be particularly beneficial in cycles where coast torque is only achieved over a short distance.

[0214] In a particular example, a fraction f=1 / 4 may be selected, which corresponds to 1 / 4 of a motor revolution (e.g., 1.25 mm for a roller screw lead of 5 mm and a gear ratio of 1:1 between the tool and the motor). In this case, every 1 / 4 of a motor revolution, i.e., the position interval (M rev The measurements are summed every 1 / 4 measurements, i.e., M rev The first set of M / 4 measurements are summed to generate a first sum partial measurement. rev A second set of / 4 measurements are summed to generate a second sum partial measurement. rev After measuring and summing the third and fourth sets of / 4 measurements, third and fourth summed partial measurements are generated in a corresponding manner. A first average value is calculated based on the first, second, third and fourth summed partial measurements. Thereafter, M rev A fifth set of 1 / 4 measurements is summed to generate a fifth summed partial measurement, and a second average value (corresponding to an updated average value) is calculated based on the second, third, fourth, and fifth summed partial measurements. The second average value is offset from the first average value by 1 / 4 of a motor revolution, but incorporates measurements from one motor revolution.

[0215] Additionally or alternatively, if a particular measurement falls within the same position interval as a previous measurement, the entirety of the particular measurement is assigned to that position interval. If a measurement straddles the boundary between a first position interval and a second position interval, a portion of the measurement is applied to the previous data set associated with the first position interval, and the remainder is assigned to a new data set associated with the second position interval. The amount of the measurement allocated to each position interval is based on the distance the tool has traveled since the previous measurement. The previous data set corresponds to measurements within the first position interval that are summed to generate a total partial measurement, and the new data set corresponds to measurements within the second position interval that are summed to generate another total partial measurement.

[0216] This alternative averaging method is described with reference to FIG. 14, where Trq1 and Trq3 are measurements taken at Pos1 and Pos3, respectively, corresponding to the motor's position during one motor revolution. Pos3 is the boundary position between the first and second position intervals of the motor revolution. That is, Pos1 and Pos3 are located on either side of Pos2, so Pos2, Pos1, and Pos3 are located at different position intervals. That is, Trq1 and Trq3 are measured at different position intervals.

[0217] The method involves estimating the value of torque Trq2 at a position Pos2 at the boundary between a first position interval and a second position interval. If the torque curve can be approximated as a straight line over a short travel distance, the value of Trq2 at point Pos2 can be calculated according to Equation 12.

[0218]

number

[0219] The portion of the measurement that is added to the previous data set (End Torque Adder) can be calculated according to Equation 13. The portion of the measurement that is added to the new data set (Start Torque Adder) can be calculated according to Equation 14.

[0220]

number

[0221] By adding a correction portion of the measured torque to the appropriate data set, errors in the data can be minimized, especially as the tool speed increases and / or the number of samples per position interval decreases.

[0222] A count may be kept corresponding to the number of measurements (or a portion thereof) in the data set. The count may then be used in an average calculation. The count may include the sum of the measurements in the data set as well as the sum of the percentage of each measurement assigned to the data set. For example, a percentage of 100 corresponds to the complete measurement being added to the data set, while a percentage less than 100 corresponds to some of the measurement being added to the first data set and some being added to the second data set. For measurements occurring near a location interval boundary, the percentage of the measurement assigned to the previous data set (Sample Count Adder) may be added. End ) can be calculated according to Equation 15, and the percentage of measurements assigned to the new data set (Sample Count Adder Start ) can be calculated according to Equation 16.

[0223]

number

[0224] These percentages can be added to the counts of the previous data set or used to provide new counts for the new data set.

[0225] Thus, the average torque over a particular position interval can be calculated according to Equation 17, where the measurements correspond to torque measurements taken during the position interval (including some measurements made near the boundaries), and the sample count adder contains the sum of all the maintained percentages, calculated, for example, according to Equations 15 and 16.

[0226]

number

[0227] Measurements near or across position interval boundaries can be taken into account to obtain more accurate data by reducing errors caused by, for example, motor-related torque fluctuations. This method can be used in parallel with other averaging methods that adjust the weighting of measurements based on the consistency of the sampled data.

[0228] Although described above with reference to coast torque, the intelligent smoothed moving average method can also be used for other parameters, such as acceleration torque. The output results of the intelligent smoothed moving average method can be used (e.g., entered into the tables described above) instead of a single measurement or simple averaging. Additionally or alternatively, the output results may be used as additional validation of previous values, for example, while calculating a weighted average for use in the acceleration torque vs. coast torque lookup table as described above.

[0229] While reference is made above to returning and / or predicting and / or adjusting coast torque or setter speed, the methods described herein may also be used with respect to other characteristics of the tool. For example, it may be beneficial to adjust clamp limits and / or deceleration torque. While the above examples describe adjustments applied specifically during the forward acceleration and actual speed advance phases 200, 202, adjustments may also be applied during other phases. For example, an adjustment may be made to the torque limit during the rivet insertion phase 204. This adjustment during the rivet insertion phase 204 may be calculated based on actual parameters measured during other phases, such as a measurement of coast torque during the actual speed advance phase 206.

[0230] Although reference has been made to measuring setter speed, acceleration torque, or coast torque, in other embodiments, other parameters may be measured (i.e., relating to other characteristics of the tool). Preferably, the tool characteristics include speed (e.g., of the setter or rivet) and / or motor torque. It should be understood that these and other characteristics may be measured using a variety of parameters. For example, rivet speed may be measured directly or inferred indirectly (e.g., by measuring speed and / or acceleration and / or displacement and / or position). For example, motor torque may be measured directly or inferred indirectly (e.g., by measuring motor speed or electrical stimulation provided to the motor, i.e., current, speed, power, etc.). Correspondingly, the predetermined parameter values ​​may be similar. It should be noted that, as will be appreciated by those skilled in the art, due to interrelationships between various features of the tool, the predetermined parameter values ​​need not relate to the same parameters as the measured parameters.

[0231] While the term "warmth" is used to describe the tool condition, it should be understood that the tool condition is not limited to temperature. A tool may have conditions ranging from a suboptimal condition (which may be referred to as cold) to an optimal condition (which may be referred to as hot). A determination of the tool condition may be a determination of how close to optimal performance the tool is. The condition may represent, for example, the amount of energy loss in the tool due to friction. Generally, a particular tool design achieves expected torque readings when operating within its normal operating temperature window. If the tool continues to require significant additional compensation regardless of its operating temperature, a warning may be generated requesting a physical inspection or other maintenance of the tool. The physical inspection may be an inspection of component wear and lubrication quality. Such a warning may be given when the tool is operating at a particular characteristic, for example, within an acceptable temperature range, and / or in response to a determination that the tool condition exceeds a condition threshold value after a minimum number of operating hours and / or insertion cycles. Such a warning may be given in response to a calculated adjustment or compensation exceeding a condition threshold value, for example, a threshold value defining the maximum adjustment that can be applied to the tool. Such a warning may be given in response to a determination that the tool condition exceeds a condition threshold for a particular number of cycles, for example, if the tool condition remains suboptimal for multiple cycles.

[0232] When referring to a motor in a fastener setting tool, the tool may additionally or alternatively include an actuator. The systems and methods herein may be applied to tools having a motor and / or an actuator. When referring to rotation of the motor, this may also be considered to apply to rotation of the actuator.

[0233] Embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and the like. Furthermore, firmware, software, routines, and instructions may be described herein as performing particular actions. However, it will be understood that such description is merely for convenience and that such actions actually result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., which in turn may cause actuators or other devices to interact with the physical world.

[0234] While specific embodiments of the invention have been described above, it will be understood that the invention may be practiced otherwise than as described. The foregoing description is intended to be illustrative and not limiting. Thus, it will be apparent to those skilled in the art that modifications can be made to the invention as described without departing from the scope of the appended claims.

Claims

1. 1. A computer-implemented method for calibrating a fastener setting tool, comprising: measuring a first parameter associated with a first characteristic of the fastener setting tool; determining a condition of the fastener setting tool by comparing the first parameter to a predetermined parameter, a difference between the first parameter and the predetermined parameter representing the condition of the fastener setting tool, the first characteristic being one of a torque of a motor of the fastener setting tool or a speed of a fastener part of the fastener setting tool; calculating an adjustment based on the comparison, the adjustment being to a second characteristic of the fastener setting tool configured to compensate for the condition of the fastener setting tool, the second characteristic being the other of a torque of a motor of the fastener setting tool or a speed of a fastener of the fastener setting tool; applying the adjustment to the fastener setting tool only if the condition satisfies a predetermined condition; A method comprising:

2. The method of claim 1 , wherein the condition represents one or more of temperature, age, usage history, and lubrication of the fastener setting tool or a component thereof.

3. 3. The method of claim 1 or 2, wherein the measurement of the first parameter is performed when the second characteristic is at a predetermined second parameter.

4. The method of any one of claims 1 to 3, further comprising inserting the fastener with an adjusted fastener setting tool.

5. The method of any one of claims 1 to 4, wherein the measuring step is performed during a first fastener insertion cycle and the adjustment is applied during the first fastener insertion cycle.

6. The method of any one of claims 1 to 4, wherein the measuring step is performed during a first fastener insertion cycle and the adjustment is applied during a second fastener insertion cycle.

7. 7. The method of claim 1, wherein the comparison is further based on one or more stored parameters stored in a memory device of the fastener setting tool, the one or more stored parameters corresponding to parameters associated with the fastener setting tool measured before measuring the first parameter.

8. 8. The method of claim 7, wherein the method is performed iteratively to form a feedback loop.

9. A method according to any preceding claim, wherein a plurality of measurements of the first parameter are made.

10. 10. The method of claim 9, wherein the plurality of measurements are taken while the first characteristic and / or the second characteristic are substantially constant.

11. 11. The method of claim 9 or 10, wherein the first parameter associated with the plurality of measurements is averaged.

12. The method of any one of claims 1 to 11, wherein the adjustment comprises a command to increase electrical stimulation provided to a motor of the fastener setting tool.

13. The method of any one of claims 1 to 12, further comprising providing a warning based on the condition of the fastener setting tool.

14. A fastener setting tool, a sensor operable to measure a first parameter associated with a first characteristic of the fastener setting tool; a data processing system, determining a condition of the fastener setting tool by comparing the first parameter to a predetermined parameter, a difference between the first parameter and the predetermined parameter representing the condition of the fastener setting tool, the first characteristic being one of a torque of a motor of the fastener setting tool or a speed of a fastener part of the fastener setting tool; calculating an adjustment based on the comparison, the adjustment being to a second characteristic of the fastener setting tool configured to compensate for a condition of the fastener setting tool, the second characteristic being the other of a torque of a motor of the fastener setting tool or a speed of a fastener portion of the fastener setting tool; and providing instructions to the fastener setting tool that include the adjustment; a data processing system including means for executing means for applying the adjustment to the fastener setting tool only if the condition satisfies a predetermined condition; A fastener fastening tool comprising:

15. A computer readable medium comprising instructions that, when executed by a data processing system of a fastener setting tool, cause the fastener setting tool to perform the steps of any one of claims 1 to 13.

Images