System and method for managing electrostatic adhesion between sheet of material and electrostatic pad

Abstract

The present disclosure relates to systems and methods for managing electrostatic adhesion between a sheet of material and an electrostatic pad. The method includes applying a voltage across the electrostatic pad to establish a baseline voltage level on the electrostatic pad and generate an electrostatic potential on the electrostatic pad; bringing the electrostatic pad close to or in contact with the sheet such that the sheet is electrostatically attached to the electrostatic pad; and monitoring a capacitance between the sheet and the electrostatic pad. If the capacitance falls below a predetermined capacitance limit, the voltage is increased to an elevated voltage level in order to increase the electrostatic adhesion between the electrostatic pad and the sheet. The system comprises a voltage module, a monitoring module and a control module.

Description

Technical Field

[0001] The present disclosure relates to managing electrostatic adhesion between a sheet of material and an electrostatic mat. Background Art

[0002] In certain manufacturing or assembly environments, carbon fiber sheets may be used, for example, to make parts in a resin infusion process. These carbon sheets may be taken from a material supply pile or station and moved to another station such as a trimming station, an infusion station, or the like.

[0003] Various methods may be used to move these carbon sheets from one station to another. One such method is directed to the use of an electrostatic pad or array of such pads carried on the end of an end effector. A voltage may be applied across the pad to generate an electrostatic adhesion potential across the pad, and the pad may then be moved into position near or in contact with the carbon sheet. With the pad positioned near or in contact with the sheet, the electrostatic adhesion potential may be used to attract and electrostatically adhere the sheet to the pad. Summary of the invention

[0004] According to one embodiment, a method for managing electrostatic adhesion between a sheet of material and an electrostatic pad includes: applying a voltage across the electrostatic pad to establish a baseline voltage level across it and generate an electrostatic potential across the electrostatic pad; bringing the electrostatic pad close to or in contact with the sheet so that the sheet is electrostatically attached to the electrostatic pad; and monitoring the capacitance between the sheet and the electrostatic pad.

[0005] The method may further comprise lifting the electrostatic pad, thereby also lifting the sheet material electrostatically attached to the electrostatic pad, and if a drop in capacitance below a predetermined capacitance limit occurs, increasing the voltage to an elevated voltage level to increase the electrostatic adhesion between the electrostatic pad and the sheet material.

[0006] In this embodiment, the capacitance falling below the predetermined capacitance limit may indicate a loss of electrostatic adhesion between the sheet and the electrostatic pad. Here, increasing the voltage may restore at least some of the loss of electrostatic adhesion between the sheet and the electrostatic pad. Increasing the voltage may restore the capacitance to or above the predetermined capacitance limit, and the loss may be less than the total loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0007] The method may further include continuing to monitor the capacitance between the sheet and the electrostatic pad and if the capacitance rises to or above the predetermined capacitance limit, reducing the voltage to the baseline voltage level. Here, the increased voltage level may be approximately twice the baseline voltage level.

[0008] The sheet material may be electrostatically attached to the electrostatic mat due to the electrostatic adhesion force generated by the electrostatic potential. The sheet material may have a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic, and the capacitance between the sheet material and the electrostatic mat may be inferred from a power curve associated with applying the voltage to the electrostatic mat.

[0009] The method may further comprise: monitoring a power curve associated with increasing the voltage when the capacitance is below the predetermined capacitance limit, and inferring the capacitance between the sheet material and the electrostatic mat from the power curve. The voltage applied to the electrostatic mat may be applied as an AC square wave having a rise time, and the capacitance between the sheet material and the electrostatic mat may be inferred from the rise time.

[0010] According to another embodiment, a method for controlling electrostatic adhesion between a sheet of material and an electrostatic pad includes placing the electrostatic pad near or in contact with the sheet so that the sheet electrostatically adheres to the electrostatic pad, and monitoring capacitance between the sheet and the electrostatic pad.

[0011] The method may further include applying a voltage across the electrostatic mat to establish a baseline voltage level across it and generating an electrostatic potential across the electrostatic mat due to the voltage applied across the electrostatic mat. The method may further include moving the electrostatic mat to move the sheet electrostatically attached to the electrostatic mat and may further include increasing the voltage to an elevated voltage level if the capacitance drops below a predetermined capacitance limit.

[0012] In this embodiment, the capacitance dropping below the predetermined capacitance limit may indicate a loss of electrostatic adhesion between the sheet and the electrostatic pad that is less than a total loss of electrostatic adhesion between the sheet and the electrostatic pad, and increasing the voltage may restore at least a portion of the loss of electrostatic adhesion between the sheet and the electrostatic pad. The sheet may have a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic, and may be electrostatically attached to the electrostatic pad due to the electrostatic adhesion generated by the electrostatic potential.

[0013] The method may also include: continuing to monitor the capacitance between the sheet and the electrostatic mat; and, if the capacitance rises to or above the predetermined capacitance limit, reducing the voltage to the baseline voltage level. The method may also include: monitoring a power curve associated with increasing the voltage when the capacitance is below the predetermined capacitance limit; and inferring the capacitance between the sheet and the electrostatic mat from the power curve. The voltage applied to the electrostatic mat may be applied as an AC square wave with a rise time, and the capacitance between the sheet and the electrostatic mat may be inferred from the rise time.

[0014] According to another embodiment, a system for managing electrostatic adhesion between a sheet of material and an electrostatic pad includes: (i) a voltage module configured to apply a voltage across the electrostatic pad to establish a baseline voltage level across the electrostatic pad and generate an electrostatic potential across the electrostatic pad; (ii) a monitoring module configured to monitor the capacitance between the sheet and the electrostatic pad; and (iii) a control module operably connected to at least the voltage module and the monitoring module.

[0015] The sheet material may have a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic, and the system may further include a movement module configured to move the electrostatic pad to a first position near the sheet material and one or more other positions away from the first position. If the capacitance drops below a predetermined capacitance limit, at least one of the monitoring module and the control module may cause the voltage module to increase the voltage to an elevated voltage level so as to increase the electrostatic adhesion between the electrostatic pad and the sheet material.

[0016] The monitoring module may be configured to continue monitoring the capacitance between the sheet and the electrostatic pad after the voltage has been increased to the elevated voltage level, and at least one of the monitoring module and the control module may be configured to cause the voltage module to reduce the voltage to the baseline voltage level if the capacitance increases to or above the predetermined capacitance limit.

[0017] In the system, at least one of the monitoring module and the control module may be configured to: when the capacitance is below the predetermined capacitance limit, monitor a power curve associated with an increase in the voltage, and infer the capacitance between the sheet material and the electrostatic pad from the power curve. Additionally, the voltage module may be configured to apply the voltage to the electrostatic pad as an AC square wave with a rise time, wherein at least one of the monitoring module and the control module is configured to infer the capacitance between the sheet material and the electrostatic pad based on the rise time.

[0018] According to another embodiment, a method for controlling electrostatic adhesion between a sheet of material and an electrostatic pad includes: (i) detecting a loss of electrostatic adhesion between the sheet and the electrostatic pad; (ii) increasing a voltage across the electrostatic pad; and (iii) restoring at least some of the loss of electrostatic adhesion between the sheet and the electrostatic pad. The method may also include: (iv) reducing the voltage across the electrostatic pad when at least some of the loss of electrostatic adhesion is restored.

[0019] The above features and advantages and other features and advantages of the present teachings as defined in the appended claims are readily apparent from the following detailed description of some of the best modes and other embodiments for carrying out the present teachings when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a series of schematic side views showing a sequence of steps for picking up a sheet of material using an electrostatic pad and illustrating the loss of electrostatic adhesion therebetween.

[0021] Figure 2 is a series of schematic side views showing a sequence of steps for picking up sheets of material using an electrostatic pad and avoiding loss of electrostatic adhesion therebetween in accordance with the present disclosure.

[0022] Figure 3 is a flow chart of steps for a method of managing electrostatic adhesion between a sheet of material and an electrostatic mat.

[0023] Figure 4 is a graph of amplitude versus time for an AC square wave power curve.

[0024] Figure 5 is a block diagram of a system for managing electrostatic adhesion between a sheet of material and an electrostatic mat.

[0025] Figure 6 is a flow chart of steps of a method for controlling electrostatic adhesion between a sheet material and an electrostatic pad.

[0026] Figure 7 is a timeline showing electrostatic adhesion, voltage, and capacitance at selected points in time.

[0027] Figure 8 is a block diagram of exemplary materials from which a sheet may be constructed. DETAILED DESCRIPTION

[0028] Referring now to the drawings, wherein like reference numerals represent like parts throughout the several views, a method 100 and system 300 for managing and / or controlling electrostatic adhesion 10 between a sheet 20 of material 21 and an electrostatic pad 30 are shown and described herein.

[0029] Figure 1 A series of schematic side views are shown, which represent a sequence of steps of picking up a sheet 20 of material 21 with an electrostatic pad 30 according to a conventional method, and illustrate the loss 14 of electrostatic adhesion 10 therebetween. Note that in Figure 1 in (and in Figure 2 1a and 1b), the electrostatic pad 30 is shown with a certain amount of cross-hatching at each step. For example, in steps 1a and 1b, the cross-hatching extends across the entire electrostatic pad 30, but in step 1c the cross-hatching decreases, and in step 1d it decreases even further, until in step 1e the cross-hatching disappears completely. The cross-hatching represents areas across the electrostatic pad 30 where the actual or potential electrostatic adhesion 10 between the electrostatic pad 30 and the sheet 20 is strong enough to keep the sheet 20 in contact with the electrostatic pad 30. Note that while the figures show areas of the electrostatic pad 30 as being fully cross-hatched (indicating sufficient electrostatic adhesion 10 in these areas), or not cross-hatched at all (indicating insufficient electrostatic adhesion 10 in these areas), this is for simplicity and illustration purposes only, as in reality the degree of electrostatic adhesion 10 spans a continuous range between completely sufficient and completely insufficient electrostatic adhesion 10.

[0030] At step 1a, an electrostatic mat 30 is positioned over the sheet 20 to be lifted and moved. Here, note that the electrostatic adhesion force 10 (i.e., cross-hatching) extends across the entire electrostatic mat 30. This potential for electrostatic adhesion force 10 (i.e., electrostatic potential) is achieved by applying an appropriate voltage or voltage difference across the electrostatic mat 30.

[0031] At step 1b, the electrostatic mat 30 and the sheet 20 are brought into contact with each other. This can be accomplished by lifting the sheet 20 and / or by lowering the electrostatic mat 30. Here, note that the electrostatic adhesion force 10 (ie, the cross hatching) still extends across the entire electrostatic mat 30.

[0032] At step 1c, it can be seen that the right edge of the sheet 20 has begun to peel off from the lower surface of the electrostatic mat 30. This peeling of the sheet 20 may be caused by various reasons, such as the electrostatic mat 30 hitting or rubbing against an external object, which causes the sheet 20 to partially fall off the electrostatic mat 30. Note that at step 1c, no cross-hatching is shown in the area of ​​the electrostatic mat 30 where the sheet 20 has been peeled off, indicating that the electrostatic adhesion 10 in this area has been damaged or weakened. In such a case where the electrostatic adhesion 10 has been locally weakened, it is generally the case that the degradation of the electrostatic adhesion 10 may continue to spread to adjacent areas of the electrostatic mat 30, thereby causing further separation between the sheet 20 and the electrostatic mat 30.

[0033] At step 1d, the sheet 20 continues to separate from the electrostatic mat 30, and the cross-hatching (i.e., electrostatic adhesion force 10) is shown to cover a smaller area than before. It can be noted that as more and more parts of the sheet 20 separate from the electrostatic mat 30, the weight of these separated parts adds greater momentum to the continuation of separation, which can be seen as a continued "domino effect" of separation.

[0034] At step 1 e , the drooping weight of the detached portion of the sheet 20 eventually becomes too great for the remaining electrostatic adhesion forces 10 to overcome until the sheet 20 is completely separated from the electrostatic pad 30 .

[0035] Compared to the conventional methods described above, disclosed herein is a method 100 and system 300 that address technical issues such as loss of electrostatic adhesion 10 between an electrostatic pad 30 and a sheet 20 of material 21 during a pick and place operation. This is accomplished by monitoring the technical effect of capacitance 50 between the electrostatic pad 30 and the sheet 20, and then maintaining capacitance 50 by applying an increasing voltage across the electrostatic pad 30 as capacitance 50 drops 52 below a predetermined capacitance limit 55 54, thereby providing significant benefits and technical advantages not taught or suggested by conventional methods. These benefits and technical advantages include increased yields, reduced waste, reduced costs, and increased reliability compared to previous methods.

[0036] Figure 2 A sequence of steps for picking up a sheet 20 of material 21 using an electrostatic pad 30 and avoiding or mitigating a loss 14 of electrostatic adhesion 10 therebetween is shown according to a method 100 of the present disclosure.

[0037] At step 2a (similar to step 1a), the electrostatic mat 30 is positioned over the sheet 20 to be lifted and moved. Here, note that the electrostatic adhesion force 10 (i.e., the cross-hatching) extends across the entire electrostatic mat 30. The electrostatic adhesion force 10 is generated by applying a voltage across the electrostatic mat 30, thereby generating an electrostatic potential 45 across the electrostatic mat 30.

[0038] At step 2b, the electrostatic pad 30 and the sheet 20 are brought into contact 28 with each other and the capacitance 50 between the electrostatic pad 30 and the sheet 20 is measured and monitored. A suitable system 300 (described in detail below) is used to apply a voltage 40 across the electrostatic pad 30 to establish a baseline voltage level 40 across it. ～ , and monitors the capacitance 50 on the electrostatic pad 20 and the sheet 20. When the electrostatic pad 30 is brought close to 26 or in contact 28 with the sheet 20 due to the electrostatic adhesion force 10 generated by the electrostatic potential 45, the sheet 20 is electrostatically attached 12 to the electrostatic pad 30.

[0039] At step 2c, the right edge of sheet 20 has detached, for example due to an external impact or disturbance, wherein the electrostatic adhesion 10 at the impact area is reduced, as shown by the lack of cross-hatching there. System 300 detects this reduction as a drop 52 in monitored capacitance 50.

[0040] At step 2d, the system 300 increases the voltage 40 to an increased or raised voltage 40 in response to detecting the decrease 52 in the monitoring capacitance 50. + This increase in voltage 40 then results in an increase in electrostatic adhesion 10, as indicated by the cross-hatching, which now extends across the entire electrostatic mat 30, and even into areas of the electrostatic mat 30 where electrostatic adhesion 10 was previously insufficient (i.e., the non-cross-hatched areas shown in step 2c).

[0041] At step 2 e , it can be seen that the increased electrostatic adhesion forces 10 caused by the increase in applied voltage 40 have become strong enough to cause the previously separated portion of the sheet 20 to be electrostatically attracted back into contact 28 with the electrostatic pad 30 .

[0042] At step 2f, with sheet 20 now in full contact 28 with electrostatic pad 30 again, system 300 detects an increase in capacitance 50 between sheet 20 and electrostatic pad 30. Once capacitance 50 has returned to a predetermined level (e.g., to the previous capacitance 50 of step 2b), system 300 reduces voltage 40 back to baseline voltage level 40. ～ .

[0043] Figure 3 1 shows a flow chart for the above method 100. At block 110, a voltage 40 is applied across the electrostatic pad 30 to establish a baseline voltage level 40 across the electrostatic pad 30. ～ , and at block 120, an electrostatic potential 45 is generated on the electrostatic pad 30 due to the applied voltage 40. (Note that here, Figure 3 as well as Figures 5 and 6) At box 130, the electrostatic pad 30 is brought into proximity 26 with or in contact 28 with the sheet 20 (by lifting the sheet 20 and / or lowering the electrostatic pad 30) such that, at box 140, the sheet 20 is electrostatically attached 12 to the electrostatic pad 30. At box 150, the capacitance 50 between the sheet 20 and the electrostatic pad 30 is monitored, for example, by the system 300 described above. At box 180, the electrostatic pad 30 is lifted or moved, thereby also lifting or moving the sheet 20 electrostatically attached to the electrostatic pad 30. (In other words, the sheet 20 is picked up by the electrostatic pad 30 using the generated electrostatic potential 45.) At box 190, the capacitance 50 is checked to determine whether it has dropped below 54 a predetermined capacitance limit 55; if it has, then at box 200, the voltage 40 is increased to an elevated voltage level 40. + , thereby increasing the electrostatic adhesion 10 between the electrostatic pad 30 and the sheet 20.

[0044] As described above, the drop 52 of capacitance 50 below the predetermined capacitance limit 55 may indicate a loss 14 of electrostatic adhesion 10 between sheet 20 and electrostatic pad 30. This loss 14 may be less than a full loss 16 of electrostatic adhesion 10, in which sheet 20 becomes completely separated from electrostatic pad 30; that is, the loss 14 may be a partial loss, in which only a portion of sheet 20 becomes separated from electrostatic pad 30. Voltage 40 decreases from baseline voltage level 40 ～ to an elevated voltage level of 40 + The increase in forces the sheet 20 to overcome the loss 14 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30 by recovering at least some 18 of the loss 14 of electrostatic adhesion.

[0045] The method 100 may also include, at block 210, continuing to monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30, and at block 220, if the capacitance 50 rises to 56 or above 58 a predetermined capacitance limit 55, then at block 230, reducing the voltage 40 to the baseline voltage level 40. ～ Here, the boost voltage level 40 + Maybe the baseline voltage level is 40 ～ About twice that of 42.

[0046] Figure 4A plot of the magnitude of a power curve 60 of an applied voltage 40, which may be in the form of an AC square wave 70, is shown versus time. A vertical axis 80 measures the magnitude of the power curve 60, while a horizontal axis 90 measures time (e.g., in milliseconds). In the case where the power curve 60 is an AC square wave 70, the power curve 60 has a rise time 92 from a minimum level 94 to a maximum level 96. The rise time 92 may be the time taken to reach 100% of the distance from the minimum level 94 to the maximum level 96, or may be the time taken to traverse a portion of the distance (e.g., 90% of the distance from the minimum level 94 to the maximum level 96, or 10% to 90% of the distance from the minimum level to the maximum level). The capacitance 50 between the sheet 20 and the electrostatic pad 30 may be inferred from the power curve 60; specifically, the capacitance 50 may be inferred from the rise time 92.

[0047] Therefore, the method 100 may also include: at block 160, when the capacitance 50 is below the predetermined capacitance limit 55, monitoring the power curve 60 associated with the increase in the voltage 40, and at block 170, inferring the capacitance 50 between the sheet 20 and the electrostatic pad 30 from the power curve 60. As described above, the voltage 40 applied to the electrostatic pad 30 may be applied as an AC square wave 70 having a rise time 92, and the capacitance 50 between the sheet 20 and the electrostatic pad 20 may be inferred from the rise time 92. Therefore, as Figure 3 As shown in , the step of monitoring capacitance 50 at block 150 may include the steps of monitoring power curve 60 at block 160 and inferring capacitance from power curve 60 (eg, from rise time 92 ) at block 170 .

[0048] It can be noted that the process flow from box 150 to boxes 160 and 170 and back to box 150, as well as the outlines of boxes 160 and 170 themselves, are shown as dashed lines. This is intended to indicate that the steps represented by boxes 160 and 170 are optional steps. That is, the step of measuring and / or monitoring capacitance 50 at box 150 can be performed by other methods other than the steps of boxes 160 and 170.

[0049] Figure 5 A block diagram of a system 300 for monitoring and maintaining electrostatic adhesion 10 between a sheet 20 and an electrostatic pad 30 is shown. The system 300 includes a voltage module 310, an optional movement module 320, a monitoring module 330, and a control module 340.

[0050] The voltage module 310 is configured to apply a voltage 40 across the electrostatic pad 30, thereby generating a baseline voltage level 40 across the electrostatic pad 30. ～and electrostatic potential 45. For example, voltage module 310 may include an alternating current (AC) or direct current (DC) power source and suitable leads, cables, or connectors for providing voltage 40 to electrostatic pad 30. Voltage module 310 is also configured to increase voltage 40 to an elevated voltage level 40 as commanded by monitoring module 330 and / or control module 340. + and the ability to reduce the voltage 40 back to the baseline voltage level 40 ～ ability.

[0051] The moving module 320 is configured to move the electrostatic pad 30 to a first position 91 near 26 the sheet 20 and one or more other positions 93 away from the first position. For example, the first position 91 may be a position where the electrostatic pad 30 is very close 26 to the sheet 20 or in direct contact 28 with the sheet 20, so that the sheet 20 is electrostatically attracted and attached to the electrostatic pad 30. The one or more other positions 93 may be positions in a manufacturing or assembly environment where the sheet 20 will be placed after being picked up by the electrostatic pad 30.

[0052] The monitoring module 330 is configured to monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30. For example, the monitoring module 330 may include a multimeter with an internal discharge capacitor or a multimeter used in conjunction with an external discharge capacitor. Alternatively, the monitoring module 330 may monitor the capacitance 50 by referring to the power curve 60 (e.g., AC square wave 70) and inferring the capacitance 50 from the rise time 92 of the power curve 60 or the AC square wave 70.

[0053] The control module 340 is operably connected to at least the voltage module 310 and the monitoring module 330. If the monitored capacitance 50 drops below the predetermined capacitance limit 55, at least one of the monitoring module 330 and the control module 340 causes the voltage module 310 to increase the voltage 40 to the elevated voltage level 40. + , thereby increasing the electrostatic adhesion 10 between the electrostatic pad 30 and the sheet 20.

[0054] Note that two or more of these modules can be combined with each other. For example, voltage module 310 and monitoring module 330 can be combined with each other. As another example, voltage module 310, monitoring module 330 and control module 340 can be combined with each other. Various other combinations are also possible.

[0055] The monitoring module 330 may be configured to continue monitoring the capacitance 50 between the sheet 20 and the electrostatic pad 30 after the voltage 40 has been increased, and at least one of the monitoring module 330 and the control module 340 may be configured to cause the voltage module 310 to reduce the voltage 40 to the baseline voltage level 40 if the capacitance 50 rises to 56 or above 58 at a predetermined capacitance limit 55. ～ .

[0056] In the system 300, at least one of the monitoring module 330 and the control module 340 may be configured to: monitor the power curve 60 associated with the increase in the voltage 40 when the capacitance 50 is below the predetermined capacitance limit 55, and infer the capacitance 50 between the sheet 20 and the electrostatic pad 30 from the power curve 60. As described above, the voltage module 310 may be configured to apply the voltage 40 to the electrostatic pad 30 as an AC square wave 70 having a rise time 92, wherein at least one of the monitoring module 330 and the control module 340 is configured to infer the capacitance 50 between the sheet 20 and the electrostatic pad 30 based on the rise time 92.

[0057] Figure 6 A flow chart showing the steps of a method 400 for controlling the electrostatic adhesion 10 between a sheet 21 and an electrostatic pad 30 is shown. The method 400 includes: (i) detecting a loss 14 of the electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30 at block 410; (ii) increasing a voltage 40 across the electrostatic pad 30 at block 420; and (iii) restoring at least some 18 of the loss 14 of the electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30 at block 430. The method 400 may also include: (iv) reducing the voltage 40 across the electrostatic pad 30 at block 440 when at least some 18 of the loss 14 of the electrostatic adhesion 10 is restored.

[0058] Figure 7 A timeline illustrating electrostatic adhesion 10, voltage 40, and capacitance 50 at selected points in time is shown. Here, voltage 40 at each point in time is represented by a wide cross-hatched rectangle, where voltage 40 is measured relative to the left vertical axis, while electrostatic adhesion 10 and capacitance 50 at each point in time are represented by a narrow non-cross-hatched rectangle that covers the corresponding voltage 40 rectangle, where electrostatic adhesion 10 and capacitance 50 are measured relative to the right vertical axis.

[0059] At the first time point t1, the voltage 40 sent to the electrostatic pad 30 is at the baseline voltage level 40 ～ , and the electrostatic adhesion 10 and the capacitance 50 are at a first level L1, wherein the first level L1 is above or greater than a predetermined capacitance limit 55. As long as the capacitance 50 is at 56 or above 58 the predetermined capacitance limit 55, the voltage 40 can be maintained at the baseline voltage level 40 ～ .

[0060] At the second point in time t2, the capacitance 50 has undergone a drop 52 from the first level L1 to a second level L2, which is below 54 a predetermined capacitance limit 55. This drop 52 in capacitance 50 corresponds to a loss 14 in electrostatic adhesion 10 which is less than 15 the total loss 16 of electrostatic adhesion 10.

[0061] At the third time point t3, and due to the drop 52 and the loss 14 detected at the second time point t2, the voltage 40 increases to the elevated voltage level 40 + , which may be a baseline voltage level of 40 ～ About twice that of 42.

[0062] At the fourth time point t4, and due to the increase in voltage 40 that began at the third time point t3, the capacitance 50 and the electrostatic adhesion 10 have increased to a third level L3 that is above the predetermined capacitance limit 55 58. This increase in capacitance 50 and the electrostatic adhesion 10 from the second level L2 to the third level L3 restores at least some 18 of the loss 14 of the electrostatic adhesion 10 detected at the second time point t2. Note that the second level L2 to which the capacitance 50 and the electrostatic adhesion 10 have been restored is illustrated as being less than the first level L1; however, the capacitance 50 and the electrostatic adhesion 10 may also be increased to the first level L1 or even higher, as long as the capacitance 50 and the electrostatic adhesion 10 are increased to 56 or above 58 at the predetermined capacitance limit 55.

[0063] At the fifth time point t5, and due to the increase in capacitance 50 and electrostatic adhesion 10 caused at the fourth time point t4, the voltage 40 may drop back to the baseline voltage level 40. ～ Please note that the durations of the time points shown are not necessarily drawn to scale and may be the same or different from each other. Furthermore, the time points may also represent respective time spans instead of, or in addition to, discrete time points.

[0064] Figure 8 A block diagram of exemplary components of a sheet 20 of material 21 is shown. As shown therein, the sheet 20 may include a fiber core 24 covered by at least one veil 22 that together form the material 21 from which the sheet 20 is made. The fiber core 24 may be made of a plurality of fibers or threads that may be woven together (e.g., in the form of a cloth or fabric) or may be in the form of a mat of chopped fibers or threads. The fibers or threads of the fiber core 24 may be made of carbon 24. c (e.g., carbon fiber), polymer 24 p (e.g., polyester, polyamide, polyethylene terephthalate, aramid, acrylic), glass 24 g (e.g., fiberglass), metal 24m (e.g., stainless steel, nickel, aluminum, titanium, copper) and ceramics 24 k (e.g., silica, alumina, basalt) or more. The cover 22 may be made of a thermoplastic material 22 tp (which can be melted by heating and then returned to solid form by cooling) or thermosetting materials 22 ts (which can be chemically activated and cured by heating).

[0065] As will be appreciated by those skilled in the relevant art(s), the system 300 and method 100 of the present disclosure may be presented or arranged in a variety of different configurations and implementations.

[0066] According to one embodiment, a method 100 for managing electrostatic adhesion 10 between a sheet 20 of material 21 and an electrostatic pad 30 includes: (i) applying a voltage 40 across the electrostatic pad 30 to establish a baseline voltage level 40 across the electrostatic pad 30 at blocks 110 and 120; ～ , and generate an electrostatic potential 45 on the electrostatic pad 30; (ii) at blocks 130 and 140, bring the electrostatic pad 30 close to 26 or contact 28 with the sheet 20 so that the sheet 20 is electrostatically attached 12 to the electrostatic pad 30; and (iii) at block 150, monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30. The method 100 may also include: at block 180, lift the electrostatic pad 30, thereby also lifting the sheet 20 that is electrostatically attached 12 to the electrostatic pad; at block 190, if the capacitance 50 drops 52 below the predetermined capacitance limit 55, then at block 200, increase the voltage 40 to an elevated voltage level 40 + , to increase the electrostatic adhesion 10 between the electrostatic pad 30 and the sheet 20.

[0067] In this embodiment, the drop 52 of capacitance 50 below the predetermined capacitance limit 55 may indicate a loss 14 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30. Here, increasing the voltage 40 may restore at least some 18 of the loss 14 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30, such as by restoring some or all of the lost or reduced electrostatic adhesion 10. The increase in voltage 40 may restore capacitance 50 to 56 or above 58 the predetermined capacitance limit 55, and the loss 14 may be less than the total loss 16 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30.

[0068] The method 100 may also include, at block 210, continuing to monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30, and at block 220, if the capacitance 50 rises to 56 or above 58 a predetermined capacitance limit 55, then at block 230, reducing the voltage 40 to the baseline voltage level 40.～ Here, the boost voltage level 40 + Maybe the baseline voltage level is 40 ～ About twice that of 42.

[0069] The sheet 20 may be electrostatically attached 12 to the electrostatic pad 30 due to the electrostatic adhesion forces 10 generated by the electrostatic potential 45. The sheet 20 of material 21 may have a carbon 24 c 、Polymer 24 p 、Glass 24 g 、Metal 24 m and ceramics 24 k The fiber core 24 is made of at least one of the above, and the capacitance 50 between the sheet 20 and the electrostatic pad 30 can be inferred from a power curve 60 associated with applying a voltage 40 to the electrostatic pad 30.

[0070] The method 100 may also include monitoring the power curve 60 associated with increasing the voltage 40 when the capacitance 50 is below the predetermined capacitance limit 55 at block 160, and inferring the capacitance 50 between the sheet 20 and the electrostatic pad 30 from the power curve 60 at block 170. The voltage 40 applied to the electrostatic pad 30 may be applied as an AC square wave 70 having a rise time 92, and the capacitance 50 between the sheet 20 and the electrostatic pad 30 may be inferred from the rise time 92.

[0071] According to another embodiment, a method 100 for controlling electrostatic adhesion 10 between a sheet 20 of material 21 and an electrostatic pad 30 includes: at box 130, placing the electrostatic pad 30 near 26 or in contact with the sheet 20 28, so that at box 140, the sheet 20 is electrostatically attached 12 to the electrostatic pad 30; and, at box 150, monitoring the capacitance 50 between the sheet 20 and the electrostatic pad 30.

[0072] The method 100 may further include, at block 110, applying a voltage 40 across the electrostatic pad 30 to establish a baseline voltage level 40 thereon. ～ ; and at block 120, an electrostatic potential 45 is generated on the electrostatic pad 30 due to the voltage 40 applied across the electrostatic pad 30. Additionally, at block 180, the method 100 may include moving the electrostatic pad 30, thereby moving the sheet 20 electrostatically attached to the electrostatic pad 30, and at block 200, may further include: if the capacitance 50 drops below the predetermined capacitance limit 55, increasing the voltage 40 to an elevated voltage level 40 + .

[0073] In this embodiment, the drop 52 of capacitance 50 below the predetermined capacitance limit 55 can indicate a loss 14 of electrostatic adhesion 10 between sheet 20 and electrostatic pad 30 that is less than a total loss 16 of electrostatic adhesion 10 between sheet 20 and electrostatic pad 30, and increasing voltage 40 can restore at least some 18 of the loss 14 of electrostatic adhesion 10 between sheet 20 and electrostatic pad 30. Sheet 20 of material 21 can have a carbon 24 c 、Polymer 24 p 、Glass 24 g 、Metal 24 m and ceramics 24 k The sheet 20 has a fiber core 24 made of at least one of the above, and due to the electrostatic adhesion force 10 generated by the electrostatic potential 45, the sheet 20 can be electrostatically attached 12 to the electrostatic pad 30.

[0074] The method 100 may also include: at block 210, continuing to monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30; at block 220, if the capacitance 50 rises to 56 or above 58 at a predetermined capacitance limit 55, then at block 230, reducing the voltage 40 to the baseline voltage level 40; ～ The method 100 may also include, at block 160, monitoring a power curve 60 associated with increasing the voltage 40 when the capacitance 50 is below a predetermined capacitance limit 55, and at block 170, inferring the capacitance 50 between the sheet 20 and the electrostatic pad 30 from the power curve 60. The voltage 40 applied to the electrostatic pad 30 may be applied as an AC square wave 70 having a rise time 92, and the capacitance 50 between the sheet 20 and the electrostatic pad 30 may be inferred from the rise time 92.

[0075] According to another embodiment, a system 300 for managing electrostatic adhesion 10 between a sheet 20 of material 21 and an electrostatic pad 30 includes: (i) a voltage module 310 configured to apply a voltage 40 across the electrostatic pad 30 to establish a baseline voltage level 40 ～ , and generates an electrostatic potential 45 on the electrostatic pad 30; (ii) a monitoring module 330, which is configured to monitor the capacitance 50 between the sheet 20 and the electrostatic pad 30; and (iii) a control module 340, which is operably connected to at least the voltage module 310 and the monitoring module 330.

[0076] The sheet 20 of material 21 may have a carbon 24 c 、Polymer 24 p 、Glass 24 g 、Metal 24 m and ceramics 24 kThe system 300 may further include a moving module 320 configured to move the electrostatic pad 30 to a first position 91 near the sheet 20 26 and one or more other positions 93 away from the first position 91. If the capacitance 50 drops below the predetermined capacitance limit 55, at least one of the monitoring module 330 and the control module 340 may cause the voltage module 310 to increase the voltage 40 to an elevated voltage level 40. + , thereby increasing the electrostatic adhesion 10 between the electrostatic pad 30 and the sheet 20.

[0077] The monitoring module 330 may be configured to: after the voltage 40 has been increased to the elevated voltage level 40 + Afterwards, the capacitance 50 between the sheet 20 and the electrostatic pad 30 continues to be monitored, and at least one of the monitoring module 330 and the control module 340 may be configured to: if the capacitance 50 rises to 56 or above 58 at a predetermined capacitance limit 55, then the voltage module 310 reduces the voltage 40 to the baseline voltage level 40. ～ .

[0078] In the system 300, at least one of the monitoring module 330 and the control module 340 may be configured to monitor the power curve 60 associated with the increase of the voltage 40 when the capacitance 50 is below the predetermined capacitance limit 55, and infer the capacitance 50 between the sheet 20 and the electrostatic pad 30 from the power curve 60. In addition, the voltage module 310 may be configured to apply the voltage 40 to the electrostatic pad 30 as an AC square wave 70 having a rise time 92, wherein at least one of the monitoring module 330 and the control module 340 is configured to infer the capacitance 50 between the sheet 20 and the electrostatic pad 30 based on the rise time 92.

[0079] According to another embodiment, a method 400 for controlling electrostatic adhesion 10 between a sheet 20 of material 21 and an electrostatic pad 30 includes: (i) detecting a loss 14 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 20 at block 410; (ii) increasing a voltage 40 across the electrostatic pad 30 at block 420; and (iii) restoring at least some 18 of the loss 14 of electrostatic adhesion 10 between the sheet 20 and the electrostatic pad 30 at block 430. The method 400 may also include: (iv) reducing the voltage 40 across the electrostatic pad 30 at block 440 when at least some 18 of the loss 14 of electrostatic adhesion 10 is restored.

[0080] Although the various steps of method 100 have been described as separate boxes, and the various functions of system 300 have been described as separate modules or elements, it can be noted that two or more steps can be combined into fewer boxes, and two or more functions can be combined into smaller modules or elements. Similarly, some steps described as a single box can be divided into two or more boxes, and some functions described as a single module or element can be divided into two or more modules or elements. Additionally, the order of the steps or boxes described herein can be rearranged in one or more different orders, and the arrangement of functions, modules, and elements can be rearranged into one or more different arrangements.

[0081] As used herein, a "module" may include hardware and / or software that includes executable instructions for receiving one or more inputs and processing the one or more inputs to provide one or more corresponding outputs. Please also note that at certain points in the present disclosure, reference may be made to a single input, output, element, etc., while at other points reference may be made to multiple / multiple inputs, outputs, elements, etc. Therefore, at any particular point in the present disclosure, it should not be considered whether inputs, outputs, elements, etc. are used in the singular or plural form, as the singular and plural usages of these words should be considered interchangeable unless the specific context dictates otherwise.

[0082] The above description is intended to be illustrative rather than restrictive. Although the size and type of the material described herein are intended to be illustrative, they are by no means restrictive, but exemplary embodiments. In the following claims, the use of the terms "first", "second", "top", "bottom", etc. is only used as a label, and is not intended to impose numerical or positional requirements on its object. As used herein, the elements or steps cited in the singular and beginning with the word "one" should be understood to not exclude multiple such elements or steps, unless such exclusion is clearly specified. Additionally, "at least one of A and B" and "A and / or B" should be understood to mean "only A, only B, or both A and B", respectively. In addition, unless explicitly stated to the contrary, the embodiments of "including" or "having" one or more elements with a specific attribute may include other such elements that do not have the attribute. And when broad descriptive adverbs such as "substantially" and "approximately" are used in this document to modify adjectives, these adverbs mean "mostly", "mainly", "most", "to a large extent" and / or "at least 51% to 99% within the possible range of 100%", and do not necessarily mean "perfectly", "completely", "strictly", "all" or "100%". Additionally, the term "proximity" in this document may be used to describe the position of an object or a part thereof relative to another object or a part thereof, and / or to describe the positional relationship of two objects or their respective parts relative to each other, and may mean "near", "adjacent", "close to", "close to", "at", etc.

[0083] In accordance with the present disclosure, this written description uses examples, including the best mode, to enable those skilled in the art to make and use devices, systems, and compositions of matter, and to perform methods. The following claims include their equivalents that define the scope of the present disclosure.

[0084] Examples of the disclosure may be described according to one or more of the following clauses.

[0085] Item 1. A method for managing electrostatic adhesion between a sheet of material and an electrostatic pad, the method comprising: applying a voltage across the electrostatic pad to establish a baseline voltage level on the electrostatic pad and generate an electrostatic potential on the electrostatic pad; bringing the electrostatic pad close to or in contact with the sheet so that the sheet is electrostatically attached to the electrostatic pad; and monitoring the capacitance between the sheet and the electrostatic pad.

[0086] Clause 2. The method according to clause 1, further comprising: lifting the electrostatic mat, thereby also lifting the sheet material statically attached to the electrostatic mat.

[0087] Clause 3. The method of clause 1, further comprising increasing the voltage to an elevated voltage level to increase the electrostatic adhesion between the electrostatic pad and the sheet material if a drop in the capacitance below a predetermined capacitance limit occurs.

[0088] Clause 4. The method of clause 3, wherein a drop in the capacitance below the predetermined capacitance limit indicates a loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0089] Clause 5. The method of Clause 4, wherein increasing the voltage recovers some of the loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0090] Clause 6. The method of Clause 4, wherein increasing the voltage restores the capacitance to or above the predetermined capacitance limit.

[0091] Clause 7. The method of Clause 4, wherein the loss is less than a total loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0092] Clause 8. The method of Clause 1, wherein the sheet material is electrostatically attached to the electrostatic pad due to the electrostatic adhesion generated by the electrostatic potential.

[0093] Clause 9. The method of clause 3, further comprising: continuing to monitor the capacitance between the sheet and the electrostatic pad; and if the capacitance rises to or above the predetermined capacitance limit, reducing the voltage to the baseline voltage level.

[0094] Clause 10. The method of Clause 3, wherein the boosted voltage level is approximately twice the baseline voltage level.

[0095] Clause 11. The method of clause 1, wherein the capacitance between the sheet and the electrostatic pad is inferred from a power curve associated with applying the voltage to the electrostatic pad.

[0096] Clause 12. The method of clause 3, further comprising: monitoring a power curve associated with increasing the voltage when the capacitance is below the predetermined capacitance limit; and inferring the capacitance between the sheet and the electrostatic pad from the power curve.

[0097] Clause 13. The method of clause 1, wherein the voltage applied to the electrostatic pad is applied as an AC square wave having a rise time, and wherein the capacitance between the sheet and the electrostatic pad is inferred from the rise time.

[0098] Clause 14. The method of Clause 1, wherein the sheet has a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic.

[0099] Item 15. A method for controlling electrostatic adhesion between a sheet of material and an electrostatic pad, the method comprising: placing the electrostatic pad near or in contact with the sheet so that the sheet electrostatically adheres to the electrostatic pad; and monitoring the capacitance between the sheet and the electrostatic pad.

[0100] Clause 16. The method of clause 15, further comprising: applying a voltage across the electrostatic pad to establish a baseline voltage level on the electrostatic pad.

[0101] Clause 17. The method of clause 16, further comprising: generating an electrostatic potential on the electrostatic mat due to a voltage applied across the electrostatic mat.

[0102] Clause 18. The method of Clause 15, further comprising: moving the electrostatic pad to move the sheet electrostatically attached to the electrostatic pad.

[0103] Clause 19. The method of Clause 16, further comprising increasing the voltage to an elevated voltage level if the capacitance drops below a predetermined capacitance limit.

[0104] Clause 20. A method according to clause 19, wherein the drop in capacitance below the predetermined capacitance limit indicates a loss of electrostatic adhesion between the sheet and the electrostatic pad, the loss being less than a total loss of electrostatic adhesion between the sheet and the electrostatic pad, and wherein increasing the voltage restores at least some of the loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0105] Clause 21. The method of Clause 17, wherein the sheet material electrostatically adheres to the electrostatic pad due to electrostatic adhesion generated by the electrostatic potential.

[0106] Clause 22. The method of clause 19, further comprising: continuing to monitor the capacitance between the sheet and the electrostatic pad; and if the capacitance rises to or above the predetermined capacitance limit, reducing the voltage to the baseline voltage level.

[0107] Clause 23. The method of clause 19, further comprising: monitoring a power curve associated with increasing the voltage when the capacitance is below the predetermined capacitance limit; and inferring the capacitance between the sheet and the electrostatic pad from the power curve.

[0108] Clause 24. The method of clause 16, wherein the voltage applied to the electrostatic pad is applied as an AC square wave having a rise time, and wherein the capacitance between the sheet and the electrostatic pad is inferred from the rise time.

[0109] Clause 25. The method of Clause 15, wherein the sheet has a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic.

[0110] Item 26. A system for managing electrostatic adhesion between a sheet of material and an electrostatic pad, the system comprising: a voltage module, the voltage module being configured to apply a voltage across the electrostatic pad, thereby establishing a baseline voltage level on the electrostatic pad and generating an electrostatic potential on the electrostatic pad; a monitoring module, the monitoring module being configured to monitor the capacitance between the sheet and the electrostatic pad; and a control module, the control module being operably connected to at least the voltage module and the monitoring module.

[0111] Clause 27. The system of clause 26, further comprising: a movement module configured to move the electrostatic pad to a first position proximate the sheet and to one or more other positions away from the first position.

[0112] Clause 28. The system of clause 26, wherein if the capacitance drops below a predetermined capacitance limit, at least one of the monitoring module and the control module causes the voltage module to increase the voltage to an elevated voltage level so as to increase the electrostatic adhesion between the electrostatic pad and the sheet.

[0113] Clause 29. A system according to clause 28, wherein the monitoring module is configured to continue monitoring the capacitance between the sheet and the electrostatic pad after the voltage has been increased to the elevated voltage level, and at least one of the monitoring module and the control module is configured to cause the voltage module to reduce the voltage to the baseline voltage level if the capacitance increases to or above the predetermined capacitance limit.

[0114] Clause 30. A system according to clause 28, wherein at least one of the monitoring module and the control module is configured to: monitor a power curve associated with the voltage increase when the capacitance is below the predetermined capacitance limit, and infer the capacitance between the sheet and the electrostatic pad from the power curve.

[0115] Clause 31. A system according to clause 26, wherein the voltage module is configured to apply the voltage to the electrostatic pad as an AC square wave having a rise time, and wherein at least one of the monitoring module and the control module is configured to infer the capacitance between the sheet and the electrostatic pad based on the rise time.

[0116] Clause 32. The system of Clause 26, wherein the sheet has a fiber core made of at least one of carbon, polymer, glass, metal, and ceramic.

[0117] Item 33. A method for controlling electrostatic adhesion between a sheet of material and an electrostatic pad, the method comprising: detecting a loss of electrostatic adhesion between the sheet and the electrostatic pad; increasing a voltage across the electrostatic pad; and restoring at least some of the loss of electrostatic adhesion between the sheet and the electrostatic pad.

[0118] Clause 34. The method of clause 33, further comprising reducing the voltage across the electrostatic pad when at least some of the loss of electrostatic adhesion is restored.

Claims

1. A method (100) of managing electrostatic adhesion (10) between a sheet (20) of material (21) and an electrostatic pad (30), the method comprising: A voltage (40) is applied (110) across the electrostatic pad (30) to establish a baseline voltage level (40) on the electrostatic pad. ～ ), and generating an electrostatic potential (45) on the electrostatic pad (30); Bringing (130) the electrostatic pad (30) close to the sheet (20) or in contact with the sheet (20) so that the sheet (20) is electrostatically attached (12) to the electrostatic pad (30); and The capacitance (50) between the sheet (20) and the electrostatic pad (30) is monitored (150).

2. The method (100) according to claim 1, further comprising: The electrostatic mat (30) is lifted (180), thereby also lifting the sheet (20) electrostatically attached (12) to the electrostatic mat.

3. The method (100) according to claim 1, further comprising: If the capacitance (50) drops (52) below a predetermined capacitance limit (55) (54), increasing (200) the voltage (40) to an elevated voltage level (40 + ) so as to increase the electrostatic adhesion (10) between the electrostatic pad (30) and the sheet (20).

4. The method (100) according to claim 3, wherein: The drop (52) of the capacitance (50) below the predetermined capacitance limit (55) indicates a loss (14) of electrostatic adhesion (10) between the sheet (20) and the electrostatic pad (30).

5. The method (100) according to claim 4, wherein: Increasing (200) the voltage (40) recovers some (18) of the loss (14) of electrostatic adhesion (10) between the sheet (20) and the electrostatic pad (30).

6. The method (100) according to claim 4, wherein: Increasing (200) the voltage (40) restores the capacitance (50) to at (56) or above (58) the predetermined capacitance limit (55).

7. The method (100) according to claim 4, wherein: The loss (14) is smaller than the total loss (16) of the electrostatic adhesion (10) between the sheet (20) and the electrostatic pad (30).

8. The method (100) of claim 1, wherein: The sheet material (20) is electrostatically attached (12) to the electrostatic pad (30) due to the electrostatic adhesion force (10) generated by the electrostatic potential (45).

9. The method (100) according to claim 3, further comprising: continuing to monitor (210) the capacitance (50) between the sheet (20) and the electrostatic pad (30); as well as If the capacitance (50) rises to (56) or above (58) the predetermined capacitance limit (55), the voltage (40) is reduced (230) to the baseline voltage level (40 ～ ).

10. The method (100) according to claim 3, wherein: The increased voltage level (40 + ) is the baseline voltage level (40 ～ ) is approximately twice as large as (42).

11. A method (100) of controlling electrostatic adhesion (10) between a sheet (20) of material (21) and an electrostatic pad (30), the method comprising: placing (130) the electrostatic pad (30) near (26) or in contact (28) with the sheet (20) such that the sheet (20) is electrostatically attached (12) to the electrostatic pad (30); and The capacitance (50) between the sheet (20) and the electrostatic pad (30) is monitored (150).

12. A system (300) for managing electrostatic adhesion (10) between a sheet (20) of material (21) and an electrostatic mat (30), the system comprising: A voltage module (310) configured to apply a voltage (40) across the electrostatic pad (30) to establish a baseline voltage level (40) on the electrostatic pad ～ ), and generating an electrostatic potential (45) on the electrostatic pad (30); A monitoring module (330) configured to monitor the capacitance (50) between the sheet (20) and the electrostatic pad (30); as well as A control module (340) is operably connected to at least the voltage module (310) and the monitoring module (330).

13. A method (400) of controlling electrostatic adhesion (10) between a sheet (20) of material (21) and an electrostatic pad (30), the method comprising: detecting (410) a loss (14) of electrostatic adhesion (10) between the sheet (20) and the electrostatic pad (30); increasing (420) the voltage (40) across the electrostatic pad (30); and At least some (18) of the loss (14) of electrostatic adhesion (10) between the sheet (20) and the electrostatic pad (30) is restored (430).

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