Magnetic coupling device provided with at least one of a sensor configuration and a demagnetization function

Abstract

A magnetic coupling device having a magnetic field sensor is disclosed. The magnetic coupling device may include a degaussing coil wrapped around a pole extension shoe of the magnetic coupling device.

Description

Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 490,705, filed Apr. 27, 2017, "Magnetically Coupled Tool with Sensor Configuration", and U.S. Provisional Patent Application No. 62 / 490,706, filed Apr. 27, 2017, "Magnetically Coupled Tool with Demagnetization Function".

Technical Field

[0002] The present disclosure relates to magnetically coupled devices, and the magnetically coupled devices have at least one sensor for determining one or more parameters indicating the quality of the magnetic circuit between the magnetically coupled device and the ferromagnetic workpiece and the relative position between the magnetically coupled device and the ferromagnetic workpiece. Further, the magnetically coupled device may include a demagnetization function.

Background Art

[0003] There are numerous devices that use magnetic fields to attract and / or secure ferromagnetic targets to the working surface of the device. Examples include magnetic clamping devices such as workpiece chucks, permanent magnet lifting devices, magnetic latches, magnetic tool stands, etc.

[0004] Generally, most of such devices include one or more sources of magnetic flux. These sources include electromagnets, permanent magnets, switched permanent magnet units or configurations, and combinations thereof. High permeability pole shoes or guides are often used to create a magnetic working circuit to transmit the magnetic flux supplied to one or more working surfaces of the device where the target is to be magnetically fixed.

[0005] In many applications and from the perspective of actual machining, the user of such a device is mainly concerned with determining the actual (tensile) force acting on the target at the working surface, or otherwise with accessing the rated data of one or more magnets employed in the device, the said rated data including the Gauss rating of the magnet assuming that all other aspects of the internal components of the magnetic working circuit are ideal. And from the said Gauss rating, the theoretical maximum tensile force that the said one or more magnets can exert on the target can be determined using established formulas, where the size, geometric shape, and ferromagnetic composition of the target allow the target to be magnetically fully saturated. That is, it is assumed that outside the circuit consisting of the magnet, pole shoe, and target, especially at the working surface, there are either no stray magnetic flux lines or only a negligible amount, where there is often an "air gap" between the pole shoe and the target, which has an adverse effect on the tensile force. Some magnet manufacturers also provide the maximum tensile force rating value of the magnet based on laboratory tests.

[0006] It is known that the actual tensile force exerted by a magnetic device on a target can be different from that determined from the Gauss rating of the magnet or the rated maximum tensile force determined experimentally. The actual or effective tensile force is reduced by a number of factors including non-uniform contact at the pole shoe-target boundary (i.e., the presence of an air gap at the said boundary), the pole shoe-target boundary not being perpendicular to the magnetic flux lines at the said boundary, the target having a "thin" dimension (which leads to stray and magnetic flux leakage of magnetic flux lines extending outward through the target, the geometric shape of the target surface, and the coating), etc.

[0007] In a magnetic device that uses a robotic arm and other positioning devices to move a device between an operating position away from a target and an operating position close to the target, it is necessary to consider the need for precise positioning of the device due to additional factors other than tensile force, such as the working surface of the device facing a specific area or zone of the target, and the above area or zone can range from simple geometric shapes such as plates or thin sheet metal stampings to more complex multi-curved shapes such as engine camshafts.

[0008] Many of these variables are difficult or impossible to predict in the use of such magnetic devices, so in order to obtain real-time information regarding qualitative and quantitative parameters related to external components of the magnetic working circuit regarding whether the target is safely attached to the working surface of the device and remains attached, and whether the tensile force remains within safe or rated thresholds, various operating methods and measurement systems have been proposed and incorporated into such magnetic devices.

[0009] Magnetic grippers are a common tool for handling steel workpieces in industrial automation. They achieve a large holding force and are relatively easy to integrate into a robotic system, but have the following specific problems. Many magnetic grippers used in the industrial field are powered by pneumatic actuators. This prevents the interface connection between most magnetic grippers and the control electronics for a fully automated process. Without an interface connection between the magnetic gripper and the control electronics, there is no easy way for the robot (and the operator) to obtain feedback from the magnetic gripper regarding the tool state or the handling performance of the workpiece.

[0010] In the industrial field, one common method related to the above is to provide additional sensors outside the magnetic gripper to detect various tool states, such as when the tool is fully on or fully off, or when the target part comes into contact with the working surface of the magnetic gripper. Although such a method of adding sensors works, it is costly to add a large number of additional sensors for specific functions. Furthermore, the sensors added outside the tool are vulnerable to damage from the movement, operation, and surrounding environment of the robot. Also, the additional sensors complicate the wiring, making the integration of the robot arm more costly and difficult.

[0011] Regardless of the layout and interface connection between the magnetic coupling device and the workpiece, it is well known that ferromagnetic workpieces exposed to a magnetic field during handling by such a device retain residual magnetism resulting from this handling operation, especially when a strong magnetic field is used to generate sufficient tensile force to fix and hold the workpiece to the device. In this regard, often, for example, when machining the workpiece after magnetic handling, or when the residual magnetism may interfere with the subsequent use of the workpiece, it is desirable that such a workpiece have no residual magnetism or have it to a negligible extent.

[0012] Similarly, for example, when the workpiece is small enough, the workpiece can be demagnetized by passing it through the magnetic field of an AC-powered demagnetization chamber (or coil), or by moving a tool equipped with a demagnetization coil over the part while generating a low-intensity alternating magnetic field (which ultimately removes the residual magnetism from the workpiece), thereby exposing the workpiece to a low-intensity alternating magnetic field.

[0013] One problem with such methodologies is that they require separate dedicated additional processing steps during the handling / machining routine of the workpiece and / or separate (additional) tools / devices to perform this operation. SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

[0014] In view of the above background, and in particular, considering the further difficulties presented by the incorporation of sensors into end-of-arm (EOA) magnetic coupling tools such as grippers and workpiece transfer facilities, it is desirable to provide a device (or tool) configured to enable the incorporation of feedback means into the magnetic coupling tool, thereby enabling excellent operation and the use of magnetic technology in robotic optics. Exemplary feedback means include an indication of whether the target (i.e., the workpiece) is properly magnetically held on the working surface of the tool, an indication of the quality of the coupling between the end-of-arm magnetic tool (EOAMT) and the workpiece, such as the accurate positioning of the tool within a predetermined threshold in the target zone of the workpiece, the detection of the proximity of the target workpiece to the EOAMT, and other factors. Further, it is also desirable to provide the magnetic coupling tool with an improved demagnetization function.

Means for Solving the Problems

[0015] Embodiments of the present disclosure relate to a magnetic coupler for lifting, transporting, and / or holding a ferromagnetic workpiece.

[0016] In certain exemplary embodiments of the present disclosure, a magnetic coupling tool is provided for magnetically coupling to a ferromagnetic workpiece. The magnetic coupling tool includes a housing and a switchable flux source supported by the housing and including a plurality of permanent magnets. The plurality of permanent magnets includes a first permanent magnet and a second permanent magnet movable relative to the first permanent magnet. The magnetic coupling tool further includes a plurality of workpiece engagement surfaces supported by the housing and magnetically coupled to the switchable flux source. The plurality of workpiece engagement surfaces are adapted to contact the ferromagnetic workpiece. A first workpiece engagement surface of the plurality of workpiece engagement surfaces corresponds to the N pole of the magnetic coupling tool, and a second workpiece engagement surface of the plurality of workpiece engagement surfaces corresponds to the S pole of the magnetic coupling tool. The magnetic coupling tool further includes a plurality of magnetic field sensors supported by the housing. A first magnetic field sensor of the plurality of magnetic field sensors is positioned to monitor a first magnetic flux associated with the first workpiece engagement surface of the plurality of workpiece engagement surfaces, and a second magnetic field sensor of the plurality of magnetic field sensors is positioned to monitor a second magnetic flux associated with the second workpiece engagement surface of the plurality of workpiece engagement surfaces. The magnetic coupling tool further includes a logic control circuit operably coupled to the plurality of magnetic field sensors. The logic control circuit is configured to determine at least one operating state of the magnetic coupling tool based on an output from at least one of the plurality of magnetic field sensors.

[0017] In one example of the above embodiment, the logic control circuit is configured to determine whether the switchable flux source is in an off state. In a variation of the above example, the logic control circuit determines whether the switchable flux source is in an off state by comparing an output of at least one of the plurality of magnetic field sensors with a first threshold value stored in a memory accessible to the logic control circuit.

[0018] In another example of the above embodiment, the logic control circuit is configured to determine whether at least one of the plurality of workpiece engagement surfaces is close to the ferromagnetic workpiece. In a variant of the above example, the logic control circuit determines whether at least one of the plurality of workpiece engagement surfaces is close to the ferromagnetic workpiece by comparing the output of at least one of the plurality of magnetic field sensors with a second threshold value stored in a memory accessible to the logic control circuit.

[0019] In a further example of the above embodiment, the logic control circuit is configured to determine the distance between the first workpiece engagement surface and the ferromagnetic workpiece. In a variant of the above example, the distance between the first workpiece engagement surface and the ferromagnetic workpiece is determined by comparing the output of the first magnetic field sensor with at least one threshold value stored in a memory accessible to the logic control circuit.

[0020] In yet another example of the above embodiment, the logic control circuit is configured to determine the orientation of the first workpiece engagement surface and the second workpiece engagement surface with respect to the ferromagnetic workpiece. In a variant of the above example, the orientation of the first workpiece engagement surface and the second workpiece engagement surface with respect to the ferromagnetic workpiece is determined by comparing the output of the first magnetic field sensor with the output of the second magnetic field sensor. In a further variant of the above example, the first distance between the first workpiece engagement surface and the ferromagnetic workpiece and the second distance between the second workpiece engagement surface and the ferromagnetic workpiece are determined by the logic control circuit to be approximately equal when the output of the first magnetic field sensor and the output of the second magnetic field sensor satisfy a first criterion. In yet a further variant of the above example, the first criterion is that the output of the first magnetic field sensor is within a threshold amount of the output of the second magnetic field sensor.

[0021] In yet another example of the above embodiment, the logic control circuit is configured to determine whether the arrangements of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece are within the target zone of the ferromagnetic workpiece. In a variant of the above example, the arrangements of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece are determined to be within the target zone of the ferromagnetic workpiece when the output of the first magnetic field sensor satisfies a first criterion and the output of the second magnetic field sensor satisfies a second criterion. In a further variant of the above example, the first criterion is that the output of the first magnetic field sensor is within a first range of magnetic flux values, and the second criterion is that the output of the second magnetic field sensor is within a second range of magnetic flux values. In a still further variant of the above example, the first range of magnetic flux values includes a first limit value corresponding to the first workpiece engaging surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the first workpiece engaging surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece. In a still further variant of the above example, the second range of magnetic flux values includes a first limit value corresponding to the second workpiece engaging surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the second workpiece engaging surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece. In yet another variant, the logic control circuit determines that the first end of the magnetic coupling tool including the first workpiece engaging surface is positioned outside the target zone when the second criterion is satisfied and the first criterion is not satisfied. In a further variant, the logic control circuit determines that the second end of the magnetic coupling tool including the second workpiece engaging surface is positioned outside the target zone when the first criterion is satisfied and the second criterion is not satisfied.

[0022] In yet another example of the above-described embodiment, the logic control circuit is configured to determine the orientations of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece at two rotation axes based on the outputs of the plurality of magnetic field sensors. In a variant of the above example, the plurality of magnetic field sensors includes a third magnetic field sensor and a fourth magnetic field sensor. The first magnetic field sensor is positioned in the left half of the magnetic coupling tool. The second magnetic field sensor is positioned in the right half of the magnetic coupling tool. The third magnetic field sensor is positioned in the front half of the magnetic coupling tool, and the front half includes a first portion of the left half and a first portion of the right half. The fourth magnetic field sensor is positioned in the rear half of the magnetic coupling tool, and the rear half includes a second portion of the left half and a second portion of the right half. The logic control circuit determines the orientations of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece at two rotation axes based on the outputs of the first magnetic field sensor, the second magnetic field sensor, the third magnetic field sensor, and the fourth magnetic field sensor, respectively. In another variant of the above example, the logic control circuit is configured to determine the orientations of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece at two rotation axes based on the outputs of the plurality of magnetic field sensors, and the first magnetic field sensor and the second magnetic field sensor are each a three-dimensional magnetic field sensor. In yet another variant of the above example, the logic control circuit is further configured to determine the distance between the magnetic coupling tool and the ferromagnetic workpiece. In a further variant, the logic control circuit is configured to determine the distance between the magnetic coupling tool and the ferromagnetic workpiece independently of the orientation of the magnetic coupling tool with respect to the ferromagnetic workpiece.

[0023] In yet another example, the logic control circuit is configured to determine whether one or more of the workpiece engaging surfaces of the pole extension shoe are in contact with the workpiece and whether the contact of the workpiece on one or more of the workpiece engaging surfaces is sufficient and within a predetermined position threshold.

[0024] In yet another example, the magnetic coupling tool further comprises an actuator operably coupled to the second permanent magnet for moving the second permanent magnet relative to the first permanent magnet. In a variation of the above example, the actuator is a stepping motor. In another variation of the above example, the logic control circuit is operably coupled to the actuator for controlling the orientation of the second permanent magnet relative to the first permanent magnet.

[0025] In still another example of the above embodiment, the second permanent magnet is rotatable relative to the first permanent magnet about an axis intersecting the second permanent magnet to change the position of the second permanent magnet relative to the first permanent magnet.

[0026] In yet another example of the above-described embodiment, the second permanent magnet is rotatable relative to the first permanent magnet about an axis that does not intersect the second permanent magnet in order to change the position of the second permanent magnet relative to the first permanent magnet. In a modification of the above example, the magnetic coupling tool further includes a first platter supported by the housing and a second platter supported by the housing. The second platter is movable relative to the first platter in order to change the position of the second permanent magnet relative to the first permanent magnet. The first platter includes a first plurality of spaced-apart permanent magnets including the first permanent magnet, each of the first plurality of spaced-apart permanent magnets having an N-pole side and an S-pole side, a first plurality of pole portions being interposed between adjacent permanent magnets of the first plurality of permanent magnets, and the first plurality of permanent magnets being arranged such that each pole portion of the first plurality of pole portions becomes one of an N-pole portion adjacent to the N-pole side of two permanent magnets of the first plurality of permanent magnets and an S-pole portion adjacent to the S-pole side of two permanent magnets of the first plurality of permanent magnets. The second platter includes a second plurality of spaced-apart permanent magnets including the second permanent magnet, each of the second plurality of spaced-apart permanent magnets having an N-pole side and an S-pole side, a second plurality of pole portions being interposed between adjacent permanent magnets of the second plurality of permanent magnets, and the second plurality of permanent magnets being arranged such that each pole portion of the second plurality of pole portions becomes one of an N-pole portion adjacent to the N-pole side of two permanent magnets of the second plurality of permanent magnets and an S-pole portion adjacent to the S-pole side of two permanent magnets of the second plurality of permanent magnets, the first magnetic sensor being associated with one of the N-pole portions of the second platter, and the second magnetic sensor being associated with one of the S-pole portions of the second platter.

[0027] In yet another example of the above embodiment, the magnetic coupling tool further comprises a plurality of pole extension shoes supported by the housing. The plurality of pole extension shoes includes a first pole extension shoe including the first workpiece engaging surface and a second pole extension shoe including the second workpiece engaging surface. The housing includes a lower side positioned between the first pole extension shoe and the second pole extension shoe, and the first pole extension shoe and the second pole extension shoe extend downwardly below the lower side of the housing. In a variation of the above example, the first pole extension shoe and the second pole extension shoe are removable from the housing.

[0028] In yet a further example of the above embodiment, the first magnetic field sensor and the second magnetic field sensor are positioned outside the envelope of the second permanent magnet.

[0029] In another example of the above embodiment, the first magnetic field sensor is positioned within the first half of the magnetic coupling tool, and the second magnetic field sensor is positioned within the second half of the magnetic coupling tool. In a variation of the above example, the first pole extension shoe is associated with a magnetic flux detection circuit surface on the opposite side of the workpiece engaging surface of the first pole extension shoe, and the first magnetic sensor is positioned above the magnetic flux detection circuit associated with the first pole extension shoe. In another variation of the above example, the housing includes a first recess, the first pole extension shoe is received within the first recess, and the first magnetic sensor is positioned directly above the first recess. In another variation of the above example, the second pole extension shoe is associated with a magnetic flux detection circuit surface on the opposite side of the workpiece engaging surface of the second pole extension shoe, and the second magnetic sensor is positioned above the magnetic flux detection circuit associated with the second pole extension shoe. In a further variation of the above example, the housing includes a second recess, the second pole extension shoe is received within the second recess, and the second magnetic sensor is positioned directly above the second recess.

[0030] In a further example of the above embodiment, the first magnetic field sensor and the second magnetic field sensor are positioned within the housing.

[0031] In yet another example of the above embodiment, the magnetic coupling tool further includes at least one temperature sensor supported by the housing, the logic control circuit is operably coupled to the at least one temperature sensor, and the logic control circuit adjusts the output received from at least one of the plurality of magnetic field sensors based on the output of the temperature sensor.

[0032] In yet another example of the above embodiment, the first magnetic field sensor and the second magnetic field sensor are each a vector magnetometer.

[0033] In another example of the above embodiment, the magnetic coupling tool further includes a communication module supported by the housing, and the logic control circuit is operably coupled to the communication module to interface with an external control electronic device.

[0034] In another example of the above embodiment, the magnetic coupling tool further includes a plurality of demagnetizing electric windings. A first demagnetizing electric winding among the plurality of demagnetizing electric windings is positioned around the first pole extension shoe among the plurality of pole extension shoes. A second demagnetizing electric winding among the plurality of demagnetizing electric windings is positioned around the second pole extension shoe among the plurality of pole extension shoes. The logic control circuit is operably coupled to the first demagnetizing electric winding and the second demagnetizing electric winding. The logic control circuit is configured to perform a demagnetization cycle using the plurality of demagnetizing electric windings. The demagnetization cycle includes generating an oscillating alternating magnetic field over a period of time using the first demagnetizing electric winding and the second demagnetizing electric winding. In a certain modification of the above example, the first pole extension shoe and the second pole extension shoe each include a first portion covered by the first and second demagnetizing electric windings, and the cross-sectional area of each of the first portions is sufficient to direct most, preferably all, of the magnetic flux generated when the first and second demagnetizing electric windings are each excited, to the first and second workpiece engaging surfaces respectively. In another modification of the above example, both the first workpiece engaging surface and the second workpiece engaging surface contact the ferromagnetic workpiece during the demagnetization cycle, and the switching magnetic flux source is in an off state.

[0035] In yet another example of the above embodiment, the magnetic coupling device further includes an output device that provides an indication of the operating state of the magnetic coupling device.

[0036] In a further example of the above embodiment, the magnetic coupling device further includes an output device that provides a plurality of distinct indicators, the plurality of distinct indicators corresponding to the plurality of distinct operating states of the magnetic coupling device. In a certain modification of the above example, the plurality of distinct indicators are each visual indicators perceptible from outside the housing. In another modification of the above example, the output device includes a plurality of lights, and the plurality of lights are controlled to provide the plurality of distinct indicators.

[0037] In another exemplary embodiment of the present disclosure, a robotic system for lifting a ferromagnetic workpiece is provided. The robotic system includes a robotic arm including a base and a plurality of movable arm segments, and a magnetic coupling device described in any one of the above-described embodiments, examples, and variations, and the magnetic coupling device is operably coupled to the robotic arm at a first end opposite the base.

[0038] In a further exemplary embodiment of the present disclosure, a method for determining at least one operating state of a magnetic coupling tool is provided. The method includes: detecting a first magnetic flux associated with the N pole of a switchable magnetic flux source supported by a housing, the switchable magnetic flux source including a plurality of permanent magnets including a first permanent magnet and a second permanent magnet movable relative to the first permanent magnet, the first magnetic flux being detected toward a first side of the switchable magnetic flux source at a position away from the workpiece engagement surface of the N pole of the magnetic coupling tool; detecting a second magnetic flux associated with the S pole of the switchable magnetic flux source, the second magnetic flux being detected toward a second side of the switchable magnetic flux source at a position away from the workpiece engagement surface of the S pole of the magnetic coupling tool, the second side being opposite the first side; and determining whether the magnetic coupling tool is in a first operating state based on at least one of the detected first magnetic flux and the detected second magnetic flux.

[0039] In an example of the above embodiment, the step of determining the first operating state of the magnetic coupling tool includes: determining whether the detected first magnetic flux satisfies a first criterion; determining whether the detected second magnetic flux satisfies a second criterion; and determining that the magnetic coupling tool is in the first operating state when the detected first magnetic flux satisfies the first criterion and the detected second magnetic flux satisfies the second criterion. In a variant of the above example, the first criterion is that the output of the first magnetic field sensor is within a first range of magnetic flux values, and the second criterion is that the output of the second magnetic field sensor is within a second range of magnetic flux values. In a further variant of the above example, the first range of magnetic flux values includes a first limit value corresponding to the first workpiece engagement surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the first workpiece engagement surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece. In yet a further variant of the above example, the second range of magnetic flux values includes a first limit value corresponding to the second workpiece engagement surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the second workpiece engagement surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece. In another variant, the method further includes determining that the first side of the magnetic coupling tool including the first workpiece engagement surface is positioned outside the target zone on the ferromagnetic workpiece when the second criterion is satisfied and the first criterion is not satisfied. In another variant of the above example, the method further includes determining that the second side of the magnetic coupling tool including the second workpiece engagement surface is positioned outside the target zone on the ferromagnetic workpiece when the first criterion is satisfied and the second criterion is not satisfied.

[0040] In another example of the above embodiment, the first operating state is a state in which the magnetic coupling tool is in an off state. In a modification of the above example, the step of determining whether the magnetic coupling tool is in the first operating state includes comparing an output of at least one of the plurality of magnetic field sensors with a first threshold value.

[0041] In yet another example of the above embodiment, the first operating state is a state in which at least one of the plurality of workpiece engaging surfaces is close to the ferromagnetic workpiece. In a modification of the above example, the step of determining whether the magnetic coupling tool is in the first operating state includes comparing an output of at least one of the plurality of magnetic field sensors with a second threshold value stored in a memory accessible by the logic control circuit.

[0042] In still another example of the above embodiment, the method further includes determining a distance between the first workpiece engaging surface and the ferromagnetic workpiece.

[0043] In yet a further example of the above embodiment, the method further includes determining an orientation of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece. In a modification of the above example, the step of determining the orientation of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece includes comparing an output of the first magnetic field sensor with an output of the second magnetic field sensor. In another modification of the above example, the first workpiece engaging surface and the second workpiece engaging surface of the magnetic coupling tool are generally parallel to the ferromagnetic workpiece when the output of the first magnetic field sensor and the output of the second magnetic field sensor satisfy a first criterion. In yet a further modification of the above example, the first criterion is that the output of the first magnetic field sensor is within a threshold amount of the output of the second magnetic field sensor.

[0044] In a further exemplary embodiment of the present disclosure, a magnetic coupling tool for magnetically coupling to a ferromagnetic workpiece is provided. The magnetic coupling tool includes: a housing; a switchable magnetic flux source supported by the housing and including a plurality of permanent magnets, the plurality of permanent magnets including a first permanent magnet and a second permanent magnet movable relative to the first permanent magnet; a plurality of pole extension shoes each having a workpiece interface, the plurality of pole extension shoes being coupled to the housing to receive magnetic flux from the switchable magnetic flux source, and the received magnetic flux being available to the ferromagnetic workpiece through each workpiece interface of the plurality of pole extension shoes; a plurality of demagnetizing electric windings, a first demagnetizing electric winding of the plurality of demagnetizing electric windings being positioned around a first pole extension shoe of the plurality of pole extension shoes, and a second demagnetizing electric winding of the plurality of demagnetizing electric windings being positioned around a second pole extension shoe of the plurality of pole extension shoes; and a logic control circuit operably coupled to the switchable magnetic flux source. The first demagnetizing electric winding, the second demagnetizing electric winding, and the logic control circuit are configured to: (i) position the second permanent magnet in a first orientation relative to the first permanent magnet; and (ii) perform a demagnetization cycle using the plurality of demagnetizing electric windings, the demagnetization cycle including generating an oscillating alternating magnetic field over a period of time using the first electric winding and the second electric winding.

[0045] In an example of the above embodiment, the first pole extension shoe and the second pole extension shoe each include a first portion covered by the first and second demagnetizing electric windings, and the cross-sectional area of each first portion is sufficient to direct most, preferably all, of the magnetic flux generated when the first and second demagnetizing electric windings are each excited, to each of the first and second workpiece engagement surfaces.

[0046] In another example of the above embodiment, both the first workpiece engaging surface and the second workpiece engaging surface contact the ferromagnetic workpiece during the demagnetization cycle, and the switching magnetic flux source is in the off state.

[0047] In a further exemplary embodiment of the present disclosure, an end - of - arm magnetic coupling tool (EOAMT) is provided, which is designed to magnetically fix a ferromagnetic workpiece to the working surface of the tool. The end - of - arm magnetic coupling tool includes: an on / off - switchable magnetic flux source; a housing component that receives the magnetic flux source; at least two pole extension shoes, each of the pole extension shoes having a workpiece engaging surface and a magnetic flux detection surface at an end opposite to the workpiece engaging surface, where the pole extension shoes are installed in the housing component or at least partially form an integral part with the housing component, thereby receiving magnetic flux from the magnetic flux source and making the magnetic flux available at the workpiece engaging surface; a number of first magnetic field detection sensors equal to the number of the pole extension shoes, each of the first magnetic field detection sensors being arranged in proximity while being separated by a predetermined distance from a relevant one of the magnetic detection surfaces of the pole extension shoes; and a logic control circuit that receives output signals from one or more of the magnetic field detection sensors and operates to determine at least one of the following operating states of the tool from the one or more output signals, the operating states being: whether the magnetic flux source is on or off; whether a ferromagnetic workpiece is spatially proximate to one or more of the workpiece engaging surfaces of the pole extension shoes; whether one or more of the workpiece engaging surfaces of the pole extension shoes are in contact with the workpiece; and whether the contact of the workpiece on one or more of the workpiece engaging surfaces is sufficient and within a predetermined position threshold.

[0048] In one example of the above-described embodiment, the first magnetic field sensor and the logic control circuit are housed within a further (second) housing component, which is preferably of a multi-component construction and is fixed to the first housing component, thereby providing an EOAMT with a small footprint in which the magnetic field detection function and the workpiece-tool boundary detection function are integrated.

[0049] In another example of the above-described embodiment, the magnetic flux source, the first housing component, and the pole extension shoe are included within an on / off switchable dipole permanent magnet unit. In a variant of the above example, the first housing component is a ferromagnetic steel housing component having a central cylindrical bore, within which two cylindrical rare earth permanent magnets magnetized in the diametrical direction are laminated such that one of the magnets is fixed so as not to rotate within the cylindrical bore and the other magnet is free to rotate upon the application of an external torque by an actuator (pneumatic, hydraulic, or electric) interfaced to this rotatable magnet. In another variant of the above example, the housing component comprises an upper non-recessed portion and a lower recessed portion, within which a rectangular pole shoe is installed, thereby forming a continuous, substantially gap-free magnetic flux delivery path towards the workpiece engagement surface provided at the free axial end of the pole shoe, and the magnetic flux detection surface on the opposite side of the workpiece engagement surface is provided at the upper end face of the non-recessed housing portion, and the housing has a substantially rectangular footprint.

[0050] In a further example of the above embodiment, in addition to the above first housing component, a second housing component is provided, which is fixed to the end of the first housing component on the opposite side of the workpiece engaging surface. In a variant of the above example, the second housing component is substantially non-magnetic and includes at least two passages, which preferably extend to end openings arranged on the opposite side of the magnetic flux detection surface of the first housing component and receive the respective two first magnetic field detection sensors. In another variant of the above example, the second housing component houses an actuator, and the actuator is interfaced with the rotatable magnet received in the first housing component to switch the magnetic flux source "on" and "off".

[0051] In yet a further variant, the logic control circuit, operable to receive output signals from one or more of the above first magnetic field detection sensors (and any additional magnetic field detection sensors) and determine one or more of the operating states of the tool from the one or more output signals, comprises a central control board, preferably a printed circuit board, which incorporates a pre-programmed or programmable microprocessor, an analog-to-digital converter (ADC) for sampling the sensor signals, and any conditioning functions. In a variant of the above example, the logic control circuit on the central control board comprises additional transistors for interfacing the general-purpose input / output (GPIO) of the processor to industrial 24V logic. In another variant of the above example, the central control board further comprises power conditioning for taking 24V from an industrial power supply and regulating it to 5V and / or 3.3V for use by the microprocessor and other circuit components, and for supplying this operating voltage to the magnetic field sensors. In yet another variant of the above example, the central control board comprises a series of blank headers for receiving a communication module, and the communication module can interface the control board to external control electronics.

[0052] In yet another example of the above-described embodiment, the first magnetic field sensor is a vector magnetometer, in particular, a solid-state linear Hall effect sensor, or a magnetoresistive sensor, which has an extremely small form factor and is embodied in a solid-state IC.

[0053] In yet a further example of the above-described embodiment, the arm tip magnetic coupling tool further comprises a visual status indicator, preferably in the form of one or more LEDs driven by the microprocessor, thereby indicating when a pre-defined one of a plurality of tool states is present or absent, for example: when the magnetic flux source is on or off; when the magnetic flux source is on and the proximity of the target is detected by the first magnetic field sensor; when the workpiece engaging surface of the tool is in contact with the workpiece outside the intended specific area on the target; and when the engagement of the tool with the workpiece is within a threshold limit, indicating a safe magnetic coupling state.

[0054] In yet a further exemplary embodiment of the present disclosure, an arm tip magnetic coupling tool is provided, which is devised to magnetically fix a ferromagnetic workpiece to the working surface of the tool. The arm tip magnetic coupling tool includes: an on / off switchable dipole magnetic flux source; a first housing component that receives the magnetic flux source; a pair of pole extension shoes, each of the pole extension shoes having a workpiece engagement surface, wherein the pole extension shoes are installed in the first housing component, thereby receiving magnetic flux from the magnetic flux source and making the magnetic flux available at the workpiece engagement surface; at least one, but preferably as many as the number of the pole extension shoes, a plurality of first magnetic field detection sensors, preferably disposed in proximity while being at a predetermined distance from a magnetic detection surface at an end of a relevant one of the pole extension shoes, on the side opposite to the workpiece engagement surface; a pair of demagnetizing electric windings, each wound around a relevant section of one of the two pole extension shoes; and a logic control circuit operable to (i) receive an output signal from the at least one magnetic field detection sensor and determine an operating state of the tool indicating that the magnetic flux source has been switched off from one or more of the output signals, (ii) turn on a power supply to the demagnetizing electric windings after detection of the off state of the magnetic flux source, and (iii) perform a demagnetization cycle in which the demagnetizing electric windings generate an oscillating alternating magnetic field over a predetermined period of time.

[0055] In one example of the above embodiment, the first magnetic field sensor and the logic control circuit are housed within a second housing component, which is preferably of a multi-component construction and is fixed to the first housing component, thereby providing an EOAMT with a small footprint in which the workpiece coupling function, the magnetic field detection function, the workpiece-tool boundary detection function, and the demagnetization function are integrated.

[0056] In another example of the above embodiment, the magnetic flux source, the first housing component, and the pole extension shoe are included within an on / off switchable dipole permanent magnet unit.

[0057] In yet another example, the first housing component is a ferromagnetic steel housing component having a central cylindrical bore, and within the central cylindrical bore, two cylindrical rare earth permanent magnets magnetized in the diametrical direction are laminated such that one of the magnets is fixed so as not to rotate within the cylindrical bore, and the other magnet is free to rotate upon the application of an external torque by an actuator interfaced with this rotatable magnet.

[0058] In still another example of the above embodiment, the pole extension shoe comprises at least two components including a first pole extension member removably fixed to the first housing component and a second pole extension member removably fixed as an extension to the first member and defining the workpiece engagement surface. In a variation of the above example, the demagnetizing electric winding surrounds a section of the second pole extension member. In another variation of the above example, the second pole shoe member has a workpiece engagement surface adapted to the contour or geometric parameters of the workpiece.

[0059] In yet another example of the above embodiment, the pole extension shoe has a cross-sectional area sufficient to direct most, preferably all, of the magnetic flux generated when the demagnetizing winding is excited to the workpiece engagement surface in the section covered by the demagnetizing winding.

[0060] In still another example, the pole extension shoe has a cross-sectional area sufficient to direct most of the magnetic flux generated when the demagnetizing winding is excited to the workpiece engagement surface in the section covered by the demagnetizing winding and to generate magnetic flux leakage around the workpiece engagement surface.

[0061] In yet another example, the first housing component includes an upper non-concave portion and a concave lower portion on opposite side portions of the housing component. The pole shoe extension member is a rectangular parallelepiped or includes the rectangular parallelepiped installed in the concave lower housing portion, whereby, together with the upper non-concave housing portion, a continuous, substantially gap-free magnetic flux delivery path is formed toward the workpiece engagement surface provided at the free axial end of the pole extension shoe. Also, the magnetic flux detection surface on the opposite side of the workpiece engagement surface is provided on the upper end surface of the non-concave housing portion. In a modification of the above example, the first housing component includes a through hole for guiding connection leads from the logic control circuit to the demagnetizing electric winding.

[0062] In a further example of the above embodiment, the second housing component is substantially non-magnetic and preferably includes at least two passages extending from the through hole of the first housing component to the logic control circuit.

[0063] In yet a further example of the above-described embodiment, the logic control circuit is devised to perform the demagnetization cycle when the tool is magnetically fixed to the workpiece by its workpiece engagement surface and after the magnetic flux source has been turned off and separation from the workpiece has been effected, while remaining stationary at the position of the workpiece. In a variant of the above example, the logic control circuit comprises a central control board, preferably a printed circuit board, which board encompasses a pre-programmed or programmable microprocessor and a circuit configuration for generating an AC signal for generating an oscillating alternating magnetic field for demagnetization in the demagnetizing winding. In another variant of the above example, the logic control circuit on the central control board comprises components for interfacing the GPIO (general-purpose input / output) of the processor to industrial 24V logic. In yet another variant of the above example, the central control board further comprises power conditioning for taking 24V from an industrial power supply and regulating it to the operating value required by the demagnetizing electrical winding for performing the demagnetization cycle.

[0064] In yet a further example, the arm tip magnetic coupling tool further comprises a visual status indicator, preferably in the form of one or more LEDs driven by the microprocessor, thereby indicating when one of a plurality of pre-defined tool states among a plurality of tool states exists or does not exist, for example: when the magnetic flux source is on or off; and when the demagnetization cycle is in progress.

[0065] In yet a further example, the demagnetizing electrical winding and the replaceable pole extension shoe member form a modular unit attachable to the first housing component, and the pole extension shoe member forms part of the magnetic flux delivery circuit of the EOAMT when used in magnetically coupling the EOAMT to the workpiece, and the pole extension shoe member also forms part of an electromagnet comprising the demagnetizing winding for demagnetizing the workpiece.

[0066] Other aspects, as well as any and / or preferred embodiments, will become apparent from the description provided below with reference to the accompanying drawings.

Brief Description of the Drawings

[0067]

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DETAILED DESCRIPTION OF THE INVENTION

[0068] In the drawings and in previous sections of this specification, terms such as "upper", "lower", "axial", and other reference terms are used to facilitate understanding of the technology described in this specification and should not be construed as absolute and limiting reference indicators unless otherwise specified. The terms "couples", "coupled", "coupler", and variations thereof are used to include both configurations in which two or more components are in physical direct contact and configurations in which two or more components are not in direct contact with each other (e.g., the above components are "coupled" via at least one third component), but cooperate or interact with each other.

[0069] Referring to FIG. 1, an exemplary magnetic coupling tool 10 is shown. The magnetic coupling tool 10 is configured to magnetically couple to a ferromagnetic workpiece 17 (see FIG. 21). The magnetic coupling tool 10 is described herein with respect to use as an end-of-arm ( "EOAMT") unit for a robotic system such as robotic system 700 (see FIG. 25), but can also be used with other lifting and transport systems for ferromagnetic materials. Exemplary lifting and transport systems include robotic systems, mechanical gantries, crane hoists, and further systems for lifting and / or transporting ferromagnetic materials. Additionally, the magnetic coupling tool 10 can also be used as part of a stationary fixture for holding at least one component for operations such as welding, inspection, and other operations. By monitoring sensor 98, logic control circuit 23 can confirm that the component held on the stationary fixture is in the correct position.

[0070] Referring to FIGS. 1 to 3, the magnetic coupling tool 10 includes a housing 11 and a switching magnetic flux source 15 supported by the housing 11 (see FIG. 3). The switching magnetic flux source 15 includes a plurality of permanent magnets exemplified by permanent magnets 30, 32 (see FIG. 3). The plurality of permanent magnets includes a first permanent magnet 30 and a second permanent magnet 32 that is movable relative to the first permanent magnet 30. The first permanent magnet 30 is fixedly held with respect to the housing 11. The magnetic coupling tool 10 further includes a plurality of workpiece engaging surfaces 44 supported by the housing 11. The plurality of workpiece engaging surfaces 44 are magnetically coupled to the switching magnetic flux source 15. The plurality of workpiece engaging surfaces 44 are adapted to contact a ferromagnetic workpiece 17 (see FIG. 21). The first workpiece engaging surface 44 of the plurality of workpiece engaging surfaces corresponds to the N pole of the magnetic coupling tool 10, and the second workpiece engaging surface 44 of the plurality of workpiece engaging surfaces corresponds to the S pole of the magnetic coupling tool 10.

[0071] The magnetic coupling tool 10 further includes a plurality of magnetic field sensors 98 supported by the housing 11 (see FIG. 3). The first magnetic field sensor 98 of the plurality of magnetic field sensors is positioned to monitor a first magnetic flux associated with the first workpiece engaging surface 44 of the plurality of workpiece engaging surfaces, and the second magnetic field sensor 98 of the plurality of magnetic field sensors is positioned to monitor a second magnetic flux associated with the second workpiece engaging surface 44 of the plurality of workpiece engaging surfaces. The magnetic coupling device 10 further includes a logic control circuit 23 operably coupled to the plurality of magnetic field sensors 98. The logic control circuit 23 is configured to determine at least one operating state of the magnetic coupling tool 10 based on an output from at least one of the plurality of magnetic field sensors 98.

[0072] In the embodiments illustrated in FIGS. 1 to 11, the magnetic coupling device 10 is an end - of - arm magnetic coupling tool (referred to herein as "EOAMT") devised to magnetically fix the ferromagnetic workpiece 17 to the working surface 44 of the tool 10. The end - of - arm magnetic coupling tool 10 includes: an on / off - switchable magnetic flux source 15; a first housing component 22 of the housing 11 that receives the magnetic flux source 15; at least two pole extension shoes 38, each of the pole extension shoes 38 having a workpiece engagement surface 44 and a magnetic flux detection surface 46 at an end opposite to the workpiece engagement surface 44. The pole extension shoes 38 are installed in the first housing component 22 or at least partially form an integral part with the housing component 22, thereby receiving magnetic flux from the magnetic flux source 15 and making the received magnetic flux available at the workpiece engagement surface 44. In the embodiment, the workpiece engagement surface 44 is part of the housing 22. The tool 10 further includes a number of magnetic field detection sensors 98. In the embodiment, the number of magnetic field detection sensors is the same as the number of pole extension shoes 38 and / or the workpiece engagement surface 44. Each magnetic field detection sensor 98 is arranged in proximity while being separated by a predetermined distance from the associated one of the magnetic detection surfaces of the pole extension shoes 38. In one example, the magnetic field detection sensors 98 are positioned within each pole extension shoe 38. In the illustrated embodiment, the magnetic field detection sensors 98 are positioned above each pole extension shoe 38. The tool 10 further includes a logic control circuit 23 that receives output signals from one or more of the magnetic field detection sensors 98 and operates to determine at least one of the following operating states of the tool from the one or more output signals: whether the magnetic flux source 15 is on or off; whether the ferromagnetic workpiece 17 is spatially proximate to one or more of the workpiece engagement surfaces 44 of the pole extension shoes 38; whether one or more of the workpiece engagement surfaces 44 of the pole extension shoes 38 are in contact with the workpiece 17; and whether the contact of the workpiece 17 on one or more of the workpiece engagement surfaces 44 is sufficient and within a predetermined positioning threshold.

[0073] In an embodiment, the first magnetic field sensor 98 and the logic control circuit 23 are housed / received within a further (second) housing component 18, which itself may be of a multi-component construction and is coupled / fixed to the first housing component 22, thereby providing a small footprint arm tip magnetically coupled tool 10 in which the magnetic field detection function and the workpiece-tool boundary detection function are integrated.

[0074] In an embodiment of the arm tip magnetically coupled tool 10, the flux source 15, the first housing component 22, and the pole extension shoe 38 are based on an on / off switchable dipole permanent magnet unit as developed by the Magswitch Group (of which the applicant is also a part). In particular, a modified Magswitch "AR" series switchable flux source may be used.

[0075] In an embodiment, the first housing component 22 is a rectangular parallelepiped-shaped ferromagnetic steel housing component having a central cylindrical bore 24, within which two cylindrical rare earth permanent magnets 30, 32 that are pole-formed in the diametrical direction are laminated (the latter providing an on / off switchable flux source). One of the magnets 30 is fixed so as not to rotate within the cylindrical bore 24, and the other magnet 32 rotates freely upon the application of an external torque using a suitable actuator 54 (pneumatic, hydraulic, or electric) that is interfaced to this rotatable magnet 32. The steel housing 22 has a generally rectangular footprint, the central bore 24 is disposed at the center of the housing 11, and the opposing housing halves with thick walls are connected only by thin wall webs and dimensioned to provide an integral pole extension piece for a device as described in U.S. Patent No. 6,707,360 (the disclosure of the above patent is hereby expressly incorporated by reference in its entirety into the present application). The lower magnet 30 is fixed to the housing component 22 in a state where the N / S pole separation plane extends (spans) between the thin wall webs, whereby the N and S poles of the magnet extend into the adjacent thick wall portions of the housing component 22 (see FIG. 4).

[0076] When the rotatable magnet 32 is rotated relative to the fixed magnet 30 and the N and S poles of these two magnets 30, 32 are aligned, the steel housing 22 is magnetically polarized, that is, the housing itself provides part or both of the pole extension shoes, whereby the magnetic flux from the magnets 30, 32 is redirected towards two magnetically separated workpiece engaging surfaces 44 provided at one axial end of the housing on the lower surface of the pole extension shoe 38. And thereby, a magnetic circuit can be formed between two opposite sides of the steel housing 22. This turns the dipole magnetic flux source “on”, that is, into the on state. When the rotatable magnet 32 is rotated relative to the fixed magnet 30 and the N and S poles of these two magnets are partially but not completely aligned, the steel housing 22 is magnetically polarized, that is, the housing 22 itself provides part or both of the pole extension shoes, whereby the magnetic flux from the magnets 30, 32 is redirected towards two magnetically separated workpiece engaging surfaces 44 provided at one axial end of the housing 22 on the lower surface of the pole extension shoe 38. And thereby, a magnetic circuit can be formed between two opposite sides of the steel housing 22. The magnetic flux available at the workpiece engaging surface 44 decreases compared to the on state, and as it approaches the magnetic flux available at the on-state workpiece engaging surface 44, the N and N poles of the two magnets 30, 32 are more aligned. This turns the dipole magnetic flux source 15 “partially on”, that is, into the partially on state. When the upper magnet 32 is rotated relative to the fixed lower magnet 30 so that the N and S poles are not aligned, the magnetic circuit is closed within the housing 22, whereby the unit is “off”, that is, in the off state, and there is virtually no usable magnetic flux that can be “tapped” when the target workpiece 17 contacts the workpiece engaging surface 44 as in the on-state or partially on-state of the unit 10.

[0077] In an embodiment, the arrangement of the magnetic field detection sensor 98 with respect to the pole extension shoe 38 provides a sensing system for the switched magnetic flux source 15. Regardless of the switched state (on state, partially on state, off state) of the switched dipole permanent magnet unit 15, there is always a certain amount of magnetic field outside near the workpiece engagement surface 44 on the lower side of the pole extension shoe 38. This leakage can be made extremely small and confined in the off state of the switched permanent magnet unit 15. However, the amount of leakage flux greatly depends on the internal magnetic circuit of the unit 10 itself, the on / partially on / off state of the unit 10, and the magnetic circuit formed between the unit 10 and a specific target workpiece 17.

[0078] When the unit 10 is in the off state (the two magnets 30, 32 are not aligned, forming a closed magnetic circuit inside the steel housing 22), the unit 10 has very little leakage flux, but it can be detected if the sensitive magnetic field sensor 98 is properly arranged. When the unit 10 is in the on state (the two magnets 30, 32 are aligned and there is no target workpiece 17 that completely shunts on or near the workpiece engagement surface 44), there is a much higher level of leakage flux. When the unit 10 is in the partially on state, the level of leakage flux is lower than in the on state and higher than in the off state.

[0079] Furthermore, in the on state or the partially on state, the amount of leakage flux is also determined by the quality of the operating magnetic circuit formed between the pole shoe 38 of the unit 10 and the workpiece 17 on the workpiece engagement surface 44, as well as the size, shape, and material of the workpiece 17 itself. The quality of this magnetic circuit is mainly determined by the thickness and relative permeability of the workpiece material, and the quality of the contact between the magnet and the workpiece 17 through the workpiece engagement surface 44. The higher the quality of the magnetic circuit, the smaller the detected leakage flux at the side of the pole shoe 38 that interacts with the workpiece 17. The quality of the above magnetic circuit increases as the workpiece 17 becomes thicker, as the relative permeability of the workpiece increases, and as the contact area between the pole shoe 38 and the workpiece 17 increases.

[0080] Due to this "leakage" effect, the magnetic field sensor 98 can monitor and derive various operating states of the unit 10 incorporating a Magswitch switched permanent magnet unit or other suitable switched magnet unit. Magswitch "AR" series devices are typically designed for use with a detachable pole shoe 38. The size and geometry of the pole shoe can be selected to suit the application field, and a dual purpose pole shoe 38 can be employed that provides two workpiece engaging surfaces with different contours at opposite axial ends.

[0081] In an embodiment, the lower portion of the first housing component 22 (having a quadrilateral cross-section) where the lower fixed magnet 30 is disposed is provided with recesses or machined on the outer opposite sides (i.e., at the thick wall portions), thereby providing a shape-conforming receiving portion or recess 29 for the two ferromagnetic pole shoes 38. In the embodiment, the outer sides of the two pole shoes 38 are selected to provide a continuous outer surface of the housing 11 without four consecutive steps when installed in the housing 11, i.e., they are rectangular parallelepiped or cubic in shape.

[0082] The upper non-recessed portion of the first housing component 22 and the lower portion of the first housing component having the replaceable cubic pole shoe 38 form a continuous, flux leakage-free as much as possible, magnetic flux delivery path towards the workpiece engaging surface 44 provided at the free axial end of the pole shoe 38. Also in this case, when the pole shoe 38 is installed in the receiving portion without a gap, the magnetic flux detection surface 46 facing the workpiece engaging surface 44 will be provided on the upper end surface of the first housing component 22. The pole shoe 38 may extend so that the workpiece engaging surface 44 can be disposed below the lower side 37 of the housing component 22 (see FIG. 3).

[0083] In an embodiment, in addition to the first housing component 22, the EOAMT 10 includes a second housing component 18 that is fixed to an end of the first housing component on the opposite side of the workpiece engaging surface 44 of the pole extension shoe 38. The second housing component 18 is substantially non-ferromagnetic and includes at least two passages 70 (see FIG. 5), which preferably extend to end openings disposed opposite the magnetic flux detection surface 46 of the first housing component 22 and receive each of the two first magnetic field detection sensors 98. With this configuration, the sensor 98 is protected from external damage, while at the same time, magnetic flux leakage from the magnetic flux detection surface 46 of the first housing component 22 is guaranteed to be sampled with minimal interference with other ferromagnetic components that may distort this magnetic field.

[0084] Taking into account robustness and noting that the second housing component 18 needs to have magnetic properties that do not significantly affect the shaping (e.g., bundling) of the magnetic flux lines passing through the magnetic flux detection surface 46 of the first housing component 22, an aluminum alloy is a preferred material option, and non-ferrous stainless steel can also be used similarly. Also, it has been found that suitable impact-resistant polymer materials having the required low relative permeability values (strengthened as required) can also be used. In this context, a low relative permeability is four to six orders of magnitude lower than the permeability of the materials used in the manufacture of the pole shoe 38 and the first housing component 22. In an embodiment, the first housing component 22 and the pole shoe 38 are made of the same material.

[0085] The second housing component 18, which is preferably also cuboid-shaped, advantageously interfaces with the rotatable magnet 32 received in the first housing component 22 to store the actuator 54 for switching the magnetic flux source 15 between an on state, an off state, and one or more partial on states, and in addition to storing the first sensor 98 to protect it from environmental influences, can serve to seal the bore 24 receiving the magnets 30, 32 against the ingress of dust and water.

[0086] In an embodiment, the logic control circuit 23 is operable to receive an output signal from the first magnetic field (and any additional) detection sensor 98 and determine one or more of the operating states of the tool 10 from the one or more output signals. In an embodiment, the logic control circuit 23 preferably comprises a central control board using a printed circuit board, the board including a pre-programmed or programmable microprocessor, an analog-to-digital converter (ADC) for sampling and optionally conditioning sensor signals, and additional transistors for interfacing the GPIO (general purpose input / output) of the processor to industrial 24V logic. The board advantageously also hosts power conditioning for taking 24V from an industrial power supply and regulating it to 5 or 3.3V, which is typically used by microprocessors and circuit components for industrial robots, and for providing an operating voltage for the magnetic field sensor.

[0087] Furthermore, the central control board may comprise a series of blank headers configured to receive a communication module, the communication module being able to interface the control board to external control electronics such as a robot controller 770 (see FIG. 25). This interface may be as simple as a stand-alone I / O connection that transmits single-bit on / off signals over 24V logic lines, or as sophisticated as a full industrial Ethernet® connection.

[0088] As described above, the central control board will advantageously use an ADC for sampling sensor signals, but may equally incorporate direct analog inputs with filtering and necessary signal conditioning, whereby the microprocessor can receive and process signals not only from the first magnetic field sensor, but also from other sensors that may equally be incorporated into the first and / or second housing components, such as the temperature sensor 31.

[0089] The first magnetic field sensor 98 may be a simple scalar magnetometer used to measure the total intensity of the magnetic field. In an embodiment, the magnetic field sensor 98 is preferably a more complex and differentiated vector magnetometer, such as a particularly bi-directional type solid state linear Hall effect sensor, a magnetoresistive sensor that can be incorporated into an integrated circuit, etc. The linear Hall effect sensor can have a very small form factor and can be embodied in a solid state IC (e.g., Honeywell SS39ET / SS49E / SS59ET series), and thus is a preferred embodiment of the first magnetic field sensor. Due to the small form factor (e.g., 3×3×1.5 mm), various linear Hall effect sensors with different magnetic field detection ranges and sensitivities can be incorporated in providing the first magnetic field sensor 98, and the various linear Hall effect sensors can be switched using a suitable logic circuit, thereby processing the output signals of each sensor and, if necessary, combining them to obtain a clearer image of the magnetic field near the magnetic flux detection surface 46 of the pole extension shoe 38 of the EOAMT10 as needed. In an embodiment, the magnetic field sensor 98 is a three-dimensional sensor having the function of sensing magnetic fields in three orthogonal directions. An exemplary magnetic field sensor is a three-dimensional magnetic sensor with model number TLV493D-A1B6, available from Infineon Technologies AG, Am Campeon 1-15, Neubiberg, Germany (85579).

[0090] As described above, in an embodiment, additional sensors such as the temperature sensor 31 may be incorporated into a suitable cavity of the first housing component 22. And the evaluation circuit of the logic circuit 23 (more precisely, the software / program used in the microprocessor to perform signal evaluation and analysis) compensates for the temperature-dependent drift of the magnetic field sensor 98 to obtain more accurate EOAMT10 positioning data.

[0091] Furthermore, in an embodiment, an additional magnetic field sensor 98 is included. Referring to FIG. 14, which is a representative top view of the unit 10, the magnetic field sensor 98 is positioned as described herein, with a first magnetic field sensor 98 positioned in the left half 101 of the magnetic coupling tool 10 and a second magnetic field sensor 98 positioned in the right half 103 of the magnetic coupling tool 10. Further, a third magnetic field sensor 98 is positioned in the front half 105 of the magnetic coupling tool 10 and a fourth magnetic field sensor 98 is positioned in the rear half 107 of the magnetic coupling tool 10. The front half 105 includes a first portion 109 of the left half 101 and a first portion 111 of the right half 103. The rear half 107 includes a second portion 113 of the left half 101 and a second portion 115 of the right half 103. The addition of the third and fourth magnetic field sensors 98 provides additional sensor values that can be used to determine various operating states of the magnetic coupling tool 10. For example, the logic control circuit 23 may determine the orientation of the workpiece engaging surface 44 relative to the ferromagnetic workpiece 17, such as left and right tilting and front and rear tilting, about two rotational axes, based on the outputs of the four magnetic field sensors.

[0092] Next, move on to the functional blocks of the logic control circuit 23. The simplest information required for the EOAMT10 is the switching state information of the magnetic flux source 15 (unit), that is, whether the unit is in the off state, on state, or partial on state. In the off state, the EOAMT10 has extremely small leakage magnetic flux or no leakage magnetic flux. In the on state, even in a substantially perfect magnetic operating circuit with the workpiece 17, the switching permanent magnet unit 15 of the EOAMT has significantly larger leakage magnetic flux than in the off state. Therefore, in the calibration process, one or more reading values of the first magnetic field sensor 98 in the off state of the EOAMT10 can be stored in the memory 33 (see FIG. 13) associated with the microprocessor of the logic control circuit 23 as calibration values or hard-coded values. When the reading value of the magnetometer rises above this off-state value or deviates from this off-state value to a certain extent, the EOAMT10 can be considered to be in the on state or partial on state. When the reading value of the magnetometer is the stored calibration value or near it, the EOAMT10 can be considered to be in the off state. In an embodiment, through the calibration process, one or more reading values of the first magnetic field sensor 98 in the desired partial on state can be stored in the memory 33 as calibration values or hard-coded values. When the reading value of the magnetometer rises to the stored specific reading value or within a few percent of the stored specific reading value, the EOAMT10 can be considered to be in the corresponding partial on state.

[0093] Using another functional block of the logic control circuit 23, it may be determined whether a ferromagnetic workpiece exists below one or both of the workpiece engagement surfaces 44 of the two pole extension shoes 38 of the EOAMT 10 when the flux source unit is in the on or partially on state. When there is no target portion for attaching the EOAMT by magnetic force (see FIG. 15), there is no "true" (i.e., external operation) magnetic circuit between the two pole shoes 38. Assuming that any workpiece 17 is sufficiently separated from the pole shoes 38 so as not to distort the magnetic field, the magnetic flux extends through the air between the lower end portions of the pole shoes 38 (mainly between the workpiece engagement surfaces 44), which in effect represents leakage magnetic flux. This also results in a relatively high leakage magnetic flux on the magnetic flux detection surface 46 of the pole extension shoe 38, causing a relatively high reading in the magnetic field sensor 98. This "max leakage flux" for a given on or partially on state is stored in the memory 33 associated with the microprocessor of the logic control circuit 23 in a hard-coded state (assuming this value is invariant) or from calibration trials during normal operation of the EOAMT 10. By setting the switched permanent magnet unit to the on or partially on state corresponding to the stored "max leakage flux" reference value and comparing the current sensor output with the stored "max leakage flux" reference value for the on or partially on state, it can be determined whether a workpiece is present.

[0094] In addition to detecting the presence or absence of the workpiece 17, the logic control circuit 23 may also provide an indication of the distance between the workpiece engaging surface 44 and the workpiece 17 when the presence of the workpiece is detected (when the current sensor value is less than the stored "maximum leakage magnetic flux" for detection of presence). In an embodiment, the logic control circuit 23 is configured to detect whether at least one of the plurality of workpiece engaging surfaces 44 is in proximity to the ferromagnetic workpiece 17. In one example, the logic control circuit 23 detects whether one of the workpiece engaging surfaces 44 is in proximity to the workpiece 17 when the current value for the corresponding sensor 98 drops below a certain threshold. The above threshold can be determined during a calibration trial and stored in the memory 33, and may correspond to a known distance between the workpiece engaging surface 44 and the workpiece 17 (see FIG. 16). In one embodiment, a plurality of thresholds are stored in the memory 33, each corresponding to one known distance. With the plurality of stored thresholds, the logic control circuit 23 can better approximate the distance between the workpiece engaging surface 44 and the workpiece 17 and can distinguish between a first distance (see FIG. 16) and a second, smaller distance (see FIG. 17). Particularly advantageous is the ability to accurately determine the proximity of the workpiece, allowing the robotic system (see FIG. 25) to move relatively quickly until the magnetic coupling unit 10 is within the first distance from the workpiece 17 and then move relatively slowly until it contacts the workpiece 17. In an embodiment, separate calibration trials or values are applied for multiple different types of ferromagnetic materials with respect to the various calibration trials and values described herein. This is because the target sensor readings can vary based on the size, shape, material, etc. of the ferromagnetic workpiece that is the target.

[0095] In an embodiment, the logic control circuit 23 is configured to determine the orientation of the first workpiece engaging surface 44 and the second workpiece engaging surface 44 relative to the ferromagnetic workpiece 17. In one example, the orientation of the first workpiece engaging surface 44 and the second workpiece engaging surface 44 relative to the ferromagnetic workpiece 17 is determined by comparing the output of the first magnetic field sensor 98 and the output of the second magnetic field sensor 98. The first spacing between the first workpiece engaging surface 44 and the ferromagnetic workpiece 17 and the second spacing between the second workpiece engaging surface 44 and the ferromagnetic workpiece 17 are determined to be approximately equal by the logic control circuit 23 if the output of the first magnetic field sensor 98 and the output of the second magnetic field sensor 98 meet a first criterion. In one example, the first criterion is that the output of the first magnetic field sensor 98 is within a threshold amount of the output of the second magnetic field sensor 98. An exemplary threshold amount is an absolute difference. In another example, the threshold amount is a percentage difference. If the first criterion is met, the workpiece engaging surface 44 has a generally equal spacing relative to the workpiece 17 (see FIG. 17). If the first criterion is not met, the workpiece engaging surface 44 has an angle relative to the workpiece 17 (see FIG. 18). If a third and fourth magnetic field sensor are incorporated as shown in FIG. 14, the angle about the pitch axis (see FIG. 19) may be determined in addition to the angle about the roll axis shown in FIG. 18.

[0096] In addition to these tool state and workpiece sensing functions, the presence and specific placement of at least two magnetic field sensors 98 at designated locations near the pole shoes 38 provides a higher level of feedback since the situation-dependent, and possibly non-uniform, distribution of leakage flux around each individual pole extension shoe can be sampled and comparatively evaluated.

[0097] In an embodiment, in the on state of the magnetic flux source 15 (which is similarly applicable to a known partial on state), although the workpiece engaging surface 44 of the pole extension shoe 38 having the N pole of the magnet is in good contact with the workpiece 17, when the pole extension shoe 38 having the S pole of the magnet is not in good contact with the workpiece 17 (see FIG. 20), there will be higher leakage magnetic flux at the S pole than at the N pole. The first magnetic field sensor 98 above the N pole and the second magnetic field sensor 98 above the S pole can detect this state, and the sensor 98 above the S pole returns a higher reading than the sensor 98 above the N pole. In one example, a bidirectional Hall effect sensor is used as the sensor 98. Therefore, by separately reading each sensor 98 and comparing the readings between them, the logic control circuit 23 can determine that the S pole is not in good contact with the workpiece 17. In an embodiment, the logic control circuit has a functional block for performing such an evaluation, which can be implemented in hardware and microprocessor software. In one example, the logic control circuit 23 determines that the contact of the S pole is not good when the readings of the N pole sensor 98 and the S pole sensor 98 exceed a threshold amount in which the readings are stored.

[0098] In an embodiment, the logic control circuit 23 is configured to determine whether the arrangement of the first workpiece engaging surface 44 and the second workpiece engaging surface 44 with respect to the ferromagnetic workpiece 17 is within the target zone 121 (see FIG. 21) on the ferromagnetic workpiece 17. In one example, the arrangement of the first workpiece engaging surface 44 and the second workpiece engaging surface 44 with respect to the ferromagnetic workpiece 17 is determined by the logic control circuit 23 to be within the target zone 121 of the ferromagnetic workpiece 17 (FIGS. 21 to 23) when the output of the first magnetic field sensor 98 satisfies a first criterion and the output of the second magnetic field sensor 98 satisfies a second criterion. An exemplary first criterion is that the output of the first magnetic field sensor 98 is within a first range of magnetic flux values, and an exemplary second criterion is that the output of the second magnetic field sensor 98 is within a second range of magnetic flux values.

[0099] Referring to FIGS. 21 - 23, a target zone 121 is illustrated. The workpiece 17 is illustrated as a sheet of material having a right end portion 125 and a left end portion 129. The target zone 121 is the portion of the workpiece 17 between a first offset 123 from the right end portion 125 of the workpiece 17 and a second offset 127 from the left end portion 129 of the workpiece 17. In one example, when the tool 10 approaches and / or crosses the second offset 127, the left pole extension shoe approaches the left end portion 129 of the workpiece 17, so the leakage flux associated with the left pole extension shoe 38 becomes higher than the magnetic flux leakage associated with the right pole extension shoe 38. Similarly, when the tool 10 approaches and / or crosses the first offset 123, the right pole extension shoe approaches the right end portion 125 of the workpiece 17, so the leakage flux associated with the right pole extension shoe 38 becomes higher than the magnetic flux leakage associated with the left pole extension shoe 38. Although a linear target zone 121 is illustrated, a two - dimensional target zone 121 may be defined with respect to the length and width of the workpiece 17. In one example, a calibration trial is performed by placing the tool at each of a first limit 123 (see FIG. 23) and a second limit 127 (see FIG. 22) and storing the corresponding leakage flux values for the magnetic flux sensors 98 at both of these limits in the memory 33. The two leakage flux values stored with respect to the first limit position (see FIG. 23) are stored in the memory 33 as "limit position 1 (limit position 1)" (one value for each sensor 98, two values). The two leakage flux values stored with respect to the second limit position (see FIG. 22) are stored in the memory 33 as "limit position 2 (limit position 2)" (one value for each sensor 98, two values). In an embodiment, the first range of the first criterion is the value between the limit position 1 and the limit position 2 (including the limit position 1 and the limit position 2) for one of the magnetic field sensors 98, and the second range of the second criterion is the value between the limit position 1 and the limit position 2 (including the limit position 1 and the limit position 2) for the other of the magnetic field sensors 98.Assuming that the first range of values corresponds to the left sensor 98 of the unit 10 and the second range of values corresponds to the right sensor 98 of the unit 10, when the second criterion is satisfied and the first criterion is not satisfied, the logic control circuit 23 determines that the left end of the tool 10 is positioned outside the target zone 121. Similarly, when the first criterion is satisfied and the second criterion is not satisfied, the logic control circuit 23 determines that the right end of the tool 10 is positioned outside the target zone 121.

[0100] In an embodiment, by using (and storing in the memory 33) the calibration values of the limit position 1 and the limit position 2 on the memory 33, the user of the tool can calibrate the signal presented by the workpiece to be turned on only when a specific magnetic activation circuit is formed (when calibrated as the same position), or only within a certain range of the magnetic activation circuit (when calibrated as two different positions). The signal positions of the N pole and the S pole can be equal to the "maximum leakage" positions of the limit positions 1 / 2, or can be outside the positions with larger leakage. These calibrations enable so-called double blank detection (DBD) and partial or range-specific confirmation. The freedom to position the N pole and the S pole outside the limit positions is intended to give the user a higher degree of freedom, especially when they are near the edge of a relatively thin steel sheet.

[0101] In an embodiment, this multi-sensor approach can also be used to provide additional tool state data. In a situation as described above, in addition to comparing two sensor readings to determine the general state of the tool and whether a workpiece is present near the workpiece engagement surface of the pole extension shoe, when the tool is even closer to the workpiece (i.e., when the presence has already been detected but the proximity has not yet been quantified), magnetic field measurements are obtained from each sensor, and by performing calculations on the difference values between the signal values of each sensor and the magnetometer readings, the orientation of the tool with respect to the workpiece can be determined, for example, at what angle the magnetic gripper including tool 10 is positioned with respect to a flat steel workpiece.

[0102] Taking this further, by using calibration trials of tool 10 for a given workpiece having known parameters (size, shape, material, etc.) and storing in memory the evaluation circuit data obtained by processing the sensor output signals during various calibration trials, even before the pole extension shoe contacts the workpiece, especially if additional magnetic field sensors are placed at positions other than the already designated positions, as shown, for example, in 14, the orientation and distance of the workpiece with respect to the target surface regarding the position of the EOAMT can be fully determined. Unit 10 exhibits leakage magnetic flux in any state, even in the off state. Therefore, a highly sensitive sensor can respond to slight variations in the leakage magnetic flux generated from the pole shoe at the detection surface of the sensor in the off state. When an EOAMT in the off state or a known partially on state approaches the workpiece, a sufficiently sensitive magnetometer can indicate proximity to the components and can deliver a signal that is converted into a control signal for the robotic arm, functioning as a kind of "vision" for the hidden robot. For example, assume that there are a total of four magnetometers, one of which is on the flux detection surface of the N - pole shoe as described above, one is on the flux detection surface of the S - pole shoe, and two additional sensors are in other positions as shown in FIG. 14. When the EOAMT is moved towards the workpiece and one of these sensors moves closer (absolutely) than the other sensors, the density of the leakage magnetic flux lines near the sensor increases and converges towards the workpiece. When the EOAMT is brought even closer to the workpiece (without changing the spatial orientation and translational movement direction of the housing component coupled to the end of the robot's arm), the magnetic flux lines redistribute more strongly across the housing component, and the density of the magnetic flux lines at the closest sensor is inversely proportional to the distance between the sensor and the workpiece. As a result, extremely high reading values are generated at the magnetometer on the adjacent sensor. By comparing the output of this adjacent magnetometer with the signal outputs from the other three magnetometers and evaluating this data, considering the known spatial relationship between the sensor and the working surface of the pole extension shoe, it is possible to indicate where the workpiece is and how close it is to the working surface of the EOAMT.

[0103] In performing accurate calculations on the output of the EOAMT's magnetometers, other functions can be realized when switching the magnetic flux source on to establish contact with the workpiece. There is a direct relationship between the amount of magnetic flux in the operating magnetic circuit and the amount of physical force that this operating magnetic circuit can withstand, which, in the case of a magnetic coupling tool, corresponds to the payload of the tool. The leakage magnetic flux from the permanent magnet depends on how much the magnetic flux is "consumed" (i.e., coupled) in the primary operating circuit, so there is a correlation between the leakage magnetic flux and the maximum payload that the coupling tool can maintain. In one embodiment, the microprocessor of the logic control circuit 23 is programmed in an appropriate manner and, by performing calibration trials, can combine and use the readings of multiple magnetometers on the tool to derive a more accurate holding force of the EOAMT than when using known devices. This can be used as a "safety check" to ensure that the EOAMT can lift the workpiece before it is moved by the robot.

[0104] In all of these situations, the microprocessor of the logic control circuit 23 receives inputs from each magnetometer 98 of the EOAMT and plays a role in performing calculations and comparisons. Next, based on the above calculations, the microprocessor determines various tool states. In an embodiment, the tool 10 communicates the determined tool state and feedback points to an external robot controller 770 (see FIG. 25). This is done by the 24V I / O or communication module 39. When the feedback is communicated to the robot controller 770, the robot controller 770 can adjust the orientation and operation of the tool 10 to address difficulties or problems during operation.

[0105] It will be understood that the logic control circuit 23 includes the components necessary to perform separation, filtering, and amplification of the signals provided by the sensors for processing by the on-board microprocessor of the EOAMT10.

[0106] In an embodiment, the EOAMT10 incorporates an input device 41 and an output device 43. Exemplary input devices include buttons, switches, levers, dials, touch displays, soft keys, and the communication module 39. Exemplary output devices include visual indicators, audio indicators, and the communication module 39. Exemplary visual indicators include displays, lights, and other visual systems. Exemplary audio indicators include speakers and other suitable audio systems. In an embodiment, the tool 10 includes simple visual status indicators in the form of one or more LEDs positioned behind the LED window 106, which are driven by the microprocessor of the logic control circuit 23 to indicate when a given tool state exists or does not exist (e.g., when the flux source 15 is off, the red LED is on; when the flux source 15 is on and the proximity of the target 17 is detected, the green LED blinks rapidly; when in contact with the target 17 outside the intended specific area 121 of the target 17 (e.g., when the magnetic actuation circuit is partially completed), the green LED blinks slowly and the yellow LED is on; when the yellow LED is off and the green LED is steadily on, it indicates engagement of the tool within the threshold limit and a safe magnetic coupling state).

[0107] Referring to FIGS. 1 - 29, further details regarding embodiments of the tool 10 are provided. Referring to FIGS. 1 and 2, an embodiment of the tool 10 is shown that can be incorporated as an arm - tip tool into a material - handling robotic device 700 (see FIG. 25) by fastening structures 12, 14 (in this case, threaded bores and dowel holes of the housing components of the tool 10 adapted to receive fastening bolts (not shown)). Other configurations / interfaces for securing the tool 10 to the robotic arm 704 of the robotic system 700, or other types of positioning devices, are known to those skilled in the art.

[0108] Tool 10 incorporates a magnetic field detection sensor 98 and an on-board sensor output signal processing circuit with an integrated microprocessor and logic control circuit 23. The logic control circuit 23 provides various tool status information data, which can be visually displayed and / or used by the controller 770 of the robot system 700 to determine: whether tool 10 is in an on state, a partially on state, or an off state; whether tool 10 is accurately positioned (within a predetermined threshold) in the target zone 121 (see FIG. 21) of the workpiece 17; whether a safe magnetic operating circuit is established between tool 10 and the target workpiece 17, and can also assist in positioning tool 10 by the robot arm 704.

[0109] Tool 10 includes two sub-assemblies, a switchable permanent magnet assembly 16 and an actuator - electronic sensor - feedback assembly 18. FIG. 3 is an exploded view of the entire tool 10, and FIGS. 4 and 5 show the permanent magnet assembly 16 and the actuator 54 - electronic sensor - feedback assembly 18, respectively.

[0110] Referring to FIG. 4, there is illustrated an embodiment of a switched permanent magnet device 20 as described in U.S. Patent No. 7,012,495 (Magswitch) (the entire disclosure of which patent is expressly incorporated herein by reference). The switched permanent magnet device 20 is a modified version of an AR type Magswitch unit manufactured and sold by Magswitch Technology Inc. The device 20 includes a ferromagnetic steel housing 22, which in the figure has a rectangular footprint and is basically a single rectangular parallelepiped body having an upper portion wider than the lower portion and both portions having the same depth. In one embodiment, the housing 22 is a multi-part housing. A circular bore 24 extends axially from the bottom to the top of the housing 22, the axis of which coincides with the intersection of the widthwise and depthwise symmetry planes of the housing 22, and thus there remain small webs 26 of material at the opposing depthwise ends of the housing 22, whereby the housing 22 is subdivided into a plurality of magnetically substantially insulated portions along the height of the housing 22. The wall thickness of the widthwise housing portion 28 is substantial and sufficient to fully carry the magnetic flux provided by two diametrically magnetized cylindrical rare earth permanent magnets 30, 32 received in the bore 24. A shunt plate 34 is inserted to close the lower end of the bore 24. The bottom magnet 30 is fixed such that it does not rotate within the bore 24 and the N-S pole separation plane (p) of the magnet 30 bisects the web portion 26 and polarizes the opposing widthwise housing portions with the N and S polarities of the dipole magnet 30, respectively. The upper magnet 32 has a hexagonal recess on its upper surface for insertion of a hexagonal drive shaft 36, and ideally, and to the extent possible, has the same magnetization characteristics as the lower magnet 30.

[0111] In the figure, two ferromagnetic pole shoes 38, made of a material that is magnetically compatible with the housing 22, or the same material as the housing 22, which basically has a substantially cuboid configuration (where the edges of the outer surfaces are chamfered), are installed on the widthwise sides of the lower part of the housing 22 using bolts 40 and locator pins 42 so as to complement the shape of the upper part of the housing 22. The pole shoes 38 preferably extend beyond the lower side 37 (see FIG. 3) of the housing 22, but are shown as being generally flush with the lower side 37 of the housing 22. The pole shoes 38 define respective workpiece engagement surfaces 44 on the lower surface, which is planar in the illustrated embodiment, but may be of a different geometric shape and / or contoured so as to form a precise abutment against the target surface of the workpiece 17 that the tool 10 magnetically couples to and handles. The fitting of the pole shoes 38 into the receiving portions defined in the lower part of the housing 22 is such as to minimize or practically avoid the air gap in the magnetic circuit, that is to say, the thick widthwise portion of the wall of the housing 22 and the pole shoes 38 together form a magnetic flux path from the magnets 30, 32 to the axial end faces at the top and bottom of the housing 22.

[0112] As described above, the pole shoes 38 define, at their lower end portions, one or more workpiece engagement (or working) surfaces of the tool, while on the other hand, the upper surface of the thick widthwise portion of the wall of the housing 22 defines what is referred to herein as the magnetic flux detection surface 46. Whether or not an external magnetic actuation circuit is present, and even if it is formed, magnetic flux lines pass through both the workpiece engagement surface 44 of the pole shoes 38 and the magnetic flux detection surface 46 of the housing 22.

[0113] For further details of such a switching permanent magnet unit 20, compare the publicly available technical information of Magswitch Technology's products, including the magnetic ratings of the Magswitch AR devices. For example, the AR50 has a maximum workpiece breakage rating of 249 kg with a safe working load of 62 kg and a safe shear load of 31 kg, and the magnet has a magnetic flux output that fully saturates a ferromagnetic workpiece with a thickness of 9.5 mm and a bottom footprint area of 52×64 mm.

[0114] Moving on to FIG. 5, an actuator - electronic sensor - feedback assembly 18 (as identified in FIG. 2) is shown. Referring to FIGS. 3 and 5, the assembly 18 comprises a housing assembly 48 consisting of four parts, which serve for different functional purposes.

[0115] The lower actuator housing part 50 having a rectangular footprint is made (machined and / or cast) from aluminum and includes a rectangular recess 52 with a through - passage opening to the lower surface of the housing part 50, which serves to house the rotary actuator 54.

[0116] The rotary actuator 54 has a torque output shaft 56, which, in the assembled state of the tool 10, is hermetically fixed to the upper part of the housing 22 of the magnetic assembly by four fastening bolts 58 that extend through four bores 59 of the lower housing part 50 and engage with the threaded bore 60 on the upper surface of the housing 22. The torque output shaft 56 is inserted into the hexagonal drive shaft insert 36 present in the upper magnet 32. Thereby, the actuator 54 can apply a selective torque to rotate the upper magnet 32 within its housing 22 to switch the switching permanent magnet device 20 between the off state, the on state, and the partial - on state. Referring to FIG. 4 in this context, as can be read from FIG. 4, the lines traversing the upper surfaces of both magnets 30 and 32 respectively represent the separation planes of the active N - and S - poles of the magnets 30 and 32.

[0117] When the N - poles and S - poles of both magnets 30 and 32 are on the same side portion in the width direction of the housing 22 and the N - pole of the permanent magnet 32 completely overlaps the N - pole of the permanent magnet 30, the device 20 is in the on - state and provides magnetic flux passing through the workpiece - engaging surface 44 of the pole shoe 38 and the magnetic - flux detection surface 46 of the housing 22. When the S - poles and N - poles of both magnets are on the same side portion in the width direction of the housing 22 and the N - pole of the permanent magnet 32 only partially overlaps the N - pole of the permanent magnet 30, the device 20 is in a partially - on state and provides magnetic flux passing through the workpiece - engaging surface 44 of the pole shoe 38 and the magnetic - flux detection surface 46 of the housing 22. When the N - poles and S - poles of both magnets 30 and 32 are on the opposing side portions of the housing 22 and the N - pole of the permanent magnet 32 completely overlaps the S - pole of the permanent magnet 30 (i.e., not aligned), the device is in the off - state and the magnetic flux is confined between the housing 22 and the magnets 30 and 32. Further details of an exemplary actuation and sensing system are provided in U.S. Patent No. 7,012,495, the disclosure of which is hereby incorporated by reference in its entirety into this application.

[0118] The lower housing part 50 also includes two coupling conduits 62 through which the actuator 54 receives hydraulic or pneumatic fluid depending on the configuration of the actuator, rotates the output shaft of the actuator 54, and turns the unit 20 on and off. In one embodiment, the actuator 54 is an electric actuator and receives power from a robot system 700. An exemplary electric actuator includes a stepper motor. The reference numeral 64 in FIGS. 3 and 5 refers to a flag and a hard stop, which are provided to limit rotation and provide reference stop / positions in the on - state rotational orientation and the off - state rotational orientation with respect to the upper magnet 32 of the unit 20. A retractable pin may be included to selectively provide reference stops for the upper magnet 32 in various partially - on states.

[0119] In an embodiment, the logic control circuit 23 monitors the rotational position of the magnet 32 and confirms that the magnet 32 has moved to an appropriate reference position regarding known partial on-states and off-states. In an example where the actuator 54 is a stepping motor, the logic control circuit 23 monitors the position signal from the stepping motor and compares this with the stored position value to determine whether the magnet 32 is in the required partial on-state or on-state.

[0120] In an embodiment, the magnetic coupling device 10 includes a brake such as a friction brake that can interact with a rotatable member coupled to the permanent magnet 32. By operating this friction brake, the current position of the rotatable member, and thus the current position of the permanent magnet 32, can be maintained.

[0121] In an embodiment, the actuator 54 is a stepping motor, and since the stepping motor can hold its output shaft in the current position, the permanent magnet 32 is also held in the current position, and thus the magnetic coupling device 10 is also held in the current state (on-state, off-state, partial on-state).

[0122] The intermediate aluminum (or other ferromagnetic metal) housing part 66 of the housing assembly 48 has a rectangular footprint and is fixed to the lower housing part 50 by the fastening bolts 58 described above. The intermediate housing part 66 has a rectangular recess 68, which is provided with a bore 69 at the widthwise ends of the recess 68 extending from the top to the bottom. The bore 69 at the widthwise ends is located outside the rectangular recess 52 of the lower housing part 50 and also coincides with a cylindrical passage channel 70 that extends from the top to the bottom surface of the lower housing part 50 or extends from the top and terminates at a position slightly away from the bottom surface.

[0123] On the upper part of the intermediate housing part 66, there is also an upper housing part 72 in the shape of a rectangular frame made of a non-ferromagnetic metal material. The upper open end thereof is closed by a rectangular non-ferromagnetic cover plate 74. The upper housing part 72 is sandwiched in a sealed state between the cover plate 74 and the intermediate housing part 66 by four fastening screws 76 extending through the bores 78 at the four corners of the upper housing part 72. Note that two of the fastening screws 76 are fixed to the threaded bores 80 on one side part in the width direction of the upper part of the intermediate housing part 66, and the other two fastening screws 76 are placed and fixed in two threaded bores 82 on the opposite side in the width direction of the upper block part 84 of the lower housing part 50. Thereby, all the housing parts 50, 66, 72 and 74 of the housing assembly 48 of the actuator - electronic sensor - feedback assembly 18 are securely fixed to each other.

[0124] Referring to FIG. 5, the actuator - electronic sensor - feedback assembly 18 further includes a magnetic field sensor - sensor signal processing circuit unit 90 which is a part of the logic control circuit 23, and this will be described with reference to FIGS. 6 and 7. The unit 90 includes two PCBs (printed circuit boards), namely a main control use PCB 92 and a magnetometer sensor PCB 94 having two leg parts 96. The two leg parts 96 support / install the above-mentioned linear Hall effect type magnetic flux sensors 98 at their respective end parts.

[0125] The main control use PCB 92 includes a microcontroller (not shown separately), an M12 electronic connector 100 for interfacing the I / O signals of the above-mentioned sensor and microcontroller with external equipment, and a lower inter-board connector 102 for coupling with a complementary inter-board connector 104 arranged on the horizontal leg of the PCB 94. The connectors 102 and 104, in addition to providing a mechanical connection between the PCBs, play a role of conducting signals between the electronic components on each board as is known in the art.

[0126] Referring to FIG. 3, the main control PCB 92 is located within the frame-like upper housing component 72 and is fixed within the upper housing component 72 in the assembled state of the upper housing component 48. The board-to-board connectors 102 and 104 are to be arranged within the rectangular through-passage 68 of the intermediate housing component 66, and the leg portion 96 of the magnetometer sensor PCB 94 extends through the rectangular through-passage 68 of the intermediate housing component 66 into the two cylindrical passage channels 70 of the lower housing component 50. With such an overall configuration, the Hall effect sensor 98 of the PCB 94 is surely arranged at a predetermined position slightly separated from the magnetic flux detection surface 46 of the housing 22. Basically, with this configuration, one of the magnetic flux sensors of the magnetometer sensor of the magnetometer sensor PCB 94 is positioned above the N pole (one of the pole extension shoes 38) of the switched permanent magnet device 20, and it is guaranteed that the other sensor 98 is positioned above the S pole (the other of the pole extension shoes 38).

[0127] The magnetic field sensor - sensor signal processing circuit unit 90 has a layout and electronic components such that it can electrically transmit the magnetic flux signal from the sensor 98 to the microcontroller / processor on the main PCB 92, can adjust these signals on the main PCB 92, and the information embedded in the above signals can be processed by the microcontroller with a series of algorithms to provide tool state feedback via the M12 electronic connector 100. This M12 electronic connector 100 is fixed to the cover plate 74 using the M12 push screw connector 105 used to attach the M12 cable assembly to the M12 electronic connector 100 linked to the microcontroller.

[0128] The main PCB 92 may incorporate one or more output devices 144, in the figure an LED, which, in addition to using signals for an external control device, receive status signals from the microcontroller / processor to provide a visual indication of a particular tool state. These tool states can be visually evaluated by the operator through the LED windows 106 present in the wall of the frame-like upper housing part 72. The tool states in any case include: whether the magnet unit 20 of the switchable permanent magnet assembly 16 is on or off; whether the N-pole pole shoe 38 (i.e., its workpiece engagement surface 44) is on the target or not (within a configurable threshold as described below) (this indicates that the N-pole shoe has good magnetic retention for the workpiece); whether the S-pole pole shoe 38 (i.e., its workpiece engagement surface 44) is on the target or not (within a configurable threshold as described below) (this indicates that the S-pole shoe has good magnetic retention for the workpiece); and the presence of a workpiece with an overall good tensile force applied (both poles are in good contact with the workpiece).

[0129] In one exemplary embodiment, the following operations were performed by tool 10: (1) reading magnetic sensor values using a microprocessor (having an ADC unit); (2) reading a plurality of sensor values using the microprocessor; (3) using the sensor read values to turn on the tool status indicator LED at specific sensor values; (4) using the sensor read values to turn on the LED related to the on / off of the tool; (5) generating an averaging function on the microprocessor to average the sensor values; (6) generating a calibration function incorporating the above average function to determine the on value for the sensor; and (7) using the calibration value from the calibration function to determine that the pole is away from the target and outside the target zone 121. In this exemplary embodiment of the EOAMT10, first, the STM320F038 Discovery board was used, and subsequently, a custom-designed main PCB board using STM32F030R8T6 was used, and software coding was performed and uploaded to the memory of the processor to implement the function settings of the tool, including calibration of the sensors and controllers of the tool.

[0130] An exemplary calibration procedure for tool 10 includes the steps of: arranging the tool in various positions with its two workpiece engagement surfaces 44 facing the workpiece 17 to be handled by tool 10; sampling a plurality of magnetic field sensor data at sensor 98 arranged proximate to the magnetic flux detection surface 46 of the housing of the magnet unit for each of the various positions; averaging the sampled data; and storing in memory 33 a threshold value that can determine the status of the tool by comparison with the raw sensor data sampled during operation of the tool. For this purpose, the STM320F038 Discovery board was configured to enable switching of the data input. The three-step calibration procedure includes the following in the specified order: 1. Switch the calibration input of input device 41 (see FIG. 13) a. Here, the tool enters the calibration mode b. Wait for the blinking of the power LED to stop 2. Position the tool with its workpiece engagement surface "ideally" in contact with and facing the workpiece, and turn on the flux unit or set it to a known partial on-state. 3. Switch the calibration input. a. Wait for the power LED to stop flashing. b. When the power LED has stopped flashing, turn off the flux unit of the tool. 4. Orient the tool with its workpiece engagement surface on the workpiece so that the S-pole shoe fits within the range that the operator (user) of the tool wants for the on-target value, and turn the unit on or to a known partial on-state. 5. Switch the calibration input. a. Wait for the power LED to stop flashing. b. When the power LED has stopped flashing, turn off the flux source of the tool. 6. Orient the tool with respect to the part so that the N-pole shoe fits within the range that the user wants for the on-target value, and turn the unit on or to a known partial on-state. 7. Switch the calibration input. a. Wait for the power LED to stop flashing. b. When the power LED has stopped flashing, turn off the unit. 8. When the power LED has stopped flashing, return the tool to the sensing mode. At this point, the status output of the tool must function properly for the calibrated on-state or known on-state. If not, repeat the calibration steps.

[0131] A sensitivity input can also be added to the firmware, allowing the user to adjust to be somewhat more sensitive from the calibration value.

[0132] Another function that can be realized with a tool equipped with an on-board sensor array and signal processing logic is the so-called "double blank" monitoring function, which uses a magnetic coupling device 10 (for example, for the transfer of a ferromagnetic sheet blank or a partially formed sheet material component between blank drawing or forming stations, or to a blank drawing or forming station) to de-stack a ferromagnetic sheet blank or a partially formed sheet material component from a staple. This function includes the following calibration of the tool: 1. Switch the calibration input a. Here, the user enters the calibration mode b. Wait for the power LED to stop blinking c. Place the tool in a state where its pole shoe is ideally in contact with one sheet made of steel, and turn on the magnetic flux source of the tool or set it to a known partial on state (Note: This step is required each time the user changes the thickness of the sheet material) 2. Switch the calibration input a. Wait for the power LED to stop blinking b. When the power LED stops blinking, turn off the unit 3. When the power LED stops blinking, return the tool to the normal sensing mode At this point, the state output of the tool must function properly. If not, repeat the calibration steps. In subsequent operations, if the sensed leakage magnetic flux regarding the calibrated on state or partial on state is lower than a certain threshold amount (absolute amount or percentage) than the stored calibrated value, the tool 10 may be coupled to multiple workpieces instead of a single workpiece.

[0133] As described herein, other configurations of magnets may be used instead of the permanent magnets 30, 32. Referring to FIGS. 26 - 30, an exemplary switched permanent magnet assembly 200 of the present disclosure is shown. The switched permanent magnet assembly 200 can replace the magnetic flux source 15. Further, the permanent magnet assembly 200 is disposed within a non - ferromagnetic housing, as opposed to the housing 22 for the magnetic coupling device 10. As will be described in more detail herein, the pole portion 250 of the permanent magnet system 200 is disposed on the lower side of the housing and contacts the workpiece 17 (see FIGS. 29 and 30), or has a pole extension member positioned directly below the pole portion 250 and contacting the workpiece 17.

[0134] The switched permanent magnet assembly 200 includes an upper platter 212 and a lower platter 214 that are to be disposed within the housing 22. The platters 212 and 214 each include a plurality of spaced permanent magnets 230 and a plurality of pole portions 250. Each of the plurality of spaced permanent magnets 230 is shown in the figure as a single permanent magnet, but may consist of a plurality of permanent magnets and / or at least one permanent magnet positioned within the housing. Exemplary platters are provided in U.S. Patent No. 7,161,451 and German Utility Model No. 202016006696, the disclosures of which are hereby expressly incorporated by reference in their entirety into this application.

[0135] Returning to the examples of FIGS. 26 to 30, each permanent magnet 230 has an N - pole side 232 and an S - pole side 234. The permanent magnets 230 and the pole portions 250 of the platters 212 and 214 are arranged such that one of the pole portions 250 forms a closed shape positioned between two of the permanent magnets 230. Further, the permanent magnets 230 are arranged such that the two permanent magnets 230 in contact with the intermediate pole portion 250 each contact the pole portion 250 with its N - pole side or its S - pole side. When the N - pole side of an adjacent permanent magnet 230 contacts the pole portion 250, the pole portion 250 is called an N - pole portion. When the S - pole side of an adjacent permanent magnet 230 contacts the pole portion 250, the pole portion 250 is called an S - pole portion.

[0136] The upper platter 212 and the lower platter 214 each include the same even number of permanent magnets 230 and the same number of pole portions 250. In one embodiment, in each of the upper platter 212 and the lower platter 214, the permanent magnets 230 and the pole portions 250 are arranged in a circular configuration.

[0137] In an embodiment, the lower platter 214 is held stationary with respect to the housing enclosing the lower platter 214, similar to the magnet 30 of the tool 10, and the upper platter 212 rotates with respect to the lower platter 214, similar to the magnet 32 of the tool 10. The upper platter 212 is rotatable with respect to the lower platter 214 in directions 290, 292 around the central axis 294, thereby changing the alignment of the permanent magnets 230 and the pole portions 250 of the upper platter 212 with respect to the permanent magnets 230 and the pole portions 250 of the lower platter 214.

[0138] When the S - pole portion 250 of the lower platter 214 is aligned with the S - pole portion 250 of the upper platter 212 and the N - pole portion 250 of the lower platter 214 is aligned with the N - pole portion 250 of the upper platter 212, the switching permanent - magnet assembly 200 is considered to be in the on state. In the on state, the workpiece is held by the magnetic - coupling device 10 due to the completion of the magnetic circuit from the aligned N - pole portions 250 of the upper platter 212 and the lower platter 214, through the workpiece, to the aligned S - pole portions 250 of the upper platter 212 and the lower platter 214.

[0139] When the S - pole portion 250 of the lower platter 214 is aligned with the N - pole portion 250 of the upper platter 212 and the N - pole portion 250 of the lower platter 214 is aligned with the S - pole portion 250 of the upper platter 212, the switching permanent - magnet assembly 200 is considered to be in the off state. In the off state, the workpiece is not held by the magnetic - coupling device 10 due to the completion of the magnetic circuit within the upper platter 212 and the lower platter 214 from the aligned N - pole portion 250 of the upper platter 212 to the S - pole portion 250 of the lower platter 214 and from the aligned S - pole portion 250 of the upper platter 212 to the N - pole portion 250 of the lower platter 214.

[0140] When the S - pole portion 250 of the upper platter 212 partially overlaps the N - pole portion 250 of the lower platter 214 and the N - pole portion 250 of the upper platter 212 partially overlaps the S - pole portion 250 of the lower platter 214, the switching permanent - magnet assembly 200 is considered to be in the partial - on state. When in the partial - on state, the workpiece can be held by the magnetic - coupling device 10 due to the completion of the magnetic circuit from the overlapping N - pole portions 250 of the upper platter 212 and the lower platter 214, through the workpiece 27, to the overlapping S - pole portions 250 of the upper platter 212 and the lower platter 214. The strength of the magnetic circuit increases as the degree of overlap of the overlapping N - pole portions 250 of the upper platter 212 and the lower platter 214 and the overlapping S - pole portions 250 of the upper platter 212 and the lower platter 214 increases.

[0141] Referring to FIG. 26, the upper platter 212 is shown. The upper platter 212 includes a cylindrical base component 220 having a central aperture 222 and a plurality of radially extending apertures 224. Each of the radially extending apertures 224 is sized and shaped to receive a permanent magnet 230. Each permanent magnet 230 has an N - pole side 232, an S - pole side 234, a radially inner side 236, a radially outer side 238, an upper portion 240, and a bottom.

[0142] Referring to FIG. 27, a top view of the upper platter 212 is shown. The cylindrical base component 220 surrounds the N - pole side 232, the S - pole side 234, the radially inner side 236, and the radially outer side 238 of each permanent magnet 230. In one embodiment, the aperture 224 is not a through - aperture but an aperture that extends from the bottom side of the cylindrical base component 220 to a certain depth, and thus the cylindrical base component 220 also surrounds the upper portion 240 of the pole portion 250. In the illustrated embodiment, the cylindrical base component 220 is a single integral component. In one embodiment, the cylindrical base component 220 consists of two or more components joined together.

[0143] As shown in FIG. 27, the permanent magnets 230 are arranged such that the N - pole sides 232 of adjacent magnets face each other and the S - pole sides 234 of adjacent magnets 230 face each other. With this configuration, the portion 250 of the cylindrical base component 220 between the permanent magnets 230 functions as a pole extension portion for the permanent magnets 230. In an embodiment, the base component 220, and thus the pole portion 250, is made of steel. Other suitable ferromagnetic materials may be used for the base component 220.

[0144] Referring to FIG. 28, the upper platter 212 is shown disassembled with respect to the lower platter 214. The lower platter 214 is generally the same as the upper platter 212. By rotating the upper platter 212 with respect to the lower platter 214, the switched permanent magnet assembly 200 can be placed in an on - state, a partially - on state, or an off - state.

[0145] Referring to FIG. 29, the upper platter 212 and the lower platter 214 are arranged in the on state, the S - pole portion 250 of the upper platter 212 is adjacent to the S - pole portion 250 of the lower platter 214, and the N - pole portion 250 of the upper platter 212 is adjacent to the N - pole portion 250 of the lower platter 214. In the on state, the workpiece 27 made of ferromagnetic material is held by the magnetic coupling device including the upper platter 212 and the lower platter 214 due to the completion of the magnetic circuit from the aligned N - pole portions 250 of the upper platter 212 and the lower platter 214, through the workpiece 27, to the aligned S - pole portions 250 of the upper platter 212 and the lower platter 214. The lower surfaces of the N - pole portion 250 and the S - pole portion 250 form a workpiece contact interface. Alternatively, although having a different shape from that of FIG. 1, an example of the pole shoe 38 may be positioned between the lower surfaces of the N - pole portion 250 and the S - pole portion 250 and the workpiece 17 to provide a workpiece contact interface 44 with the workpiece 17. Further, the sensor 98 may be positioned adjacent to various ones of the N - pole portion 250 and the S - pole portion 250. In an embodiment, at least one of the N - pole portions 250 and at least one of the S - pole portions 250 have associated sensors 98, thereby monitoring the leakage magnetic flux associated with each N - pole portion and each S - pole portion. As shown in FIG. 27, the first sensor 98 may be arranged close to the N - pole portion 250, for example, directly above the N - pole portion 250 or radially outside the N - pole portion 250, and the second sensor 98 may be arranged close to the S - pole portion 250, for example, directly above the S - pole portion 250 or radially outside the S - pole portion 250. The logic control circuit 23 may perform calibration trials with respect to the permanent magnet assembly 200 in a manner similar to that described herein with respect to the magnetic coupling device 10, thereby storing sensor values for determining the operating state of the device including the permanent magnet assembly 200.

[0146] Referring to FIG. 30, when the S - pole portion 250 of the upper platter 212 is adjacent to the N - pole portion 250 of the lower platter 214 and the N - pole portion 250 of the upper platter 212 is adjacent to the S - pole portion 250 of the lower platter 214, the upper platter 212 and the lower platter 214 are arranged in an off state. In the off state, the ferromagnetic workpiece 27 is not held by the magnetic coupling device including the upper platter 212 and the lower platter 214 due to the completion of the magnetic circuits between the aligned S - pole portion 250 of the upper platter 212 and the N - pole portion 250 of the lower platter 214, and between the aligned N - pole portion 250 of the upper platter 212 and the S - pole portion 250 of the lower platter 214. In other words, the platters 212 and 214 shunt the magnetic circuits within the pole portion 150 and disrupt the external magnetic field. The upper platter 212 and the lower platter 214 can also be arranged to provide one or more partial - on states of the magnetic coupling device including the upper platter 212 and the lower platter 214.

[0147] As described herein, other configurations of magnets may be used instead of the permanent magnets 30, 32. Referring to FIGS. 31 - 33, an exemplary switchable permanent - magnet assembly 300 of the present disclosure is shown. The switchable permanent - magnet assembly 300 can replace the magnetic - flux source 15. Further, the permanent - magnet assembly 300 is disposed within a non - ferromagnetic housing, as opposed to the housing 22 for the magnetic coupling device 10. As will be described in more detail herein, the pole portion 350 of the permanent - magnet system 300 is disposed below the housing and contacts the workpiece 17 or has a pole - extension member 340 positioned directly below the pole portion 350 and contacting the workpiece 17 (see FIGS. 31 - 33).

[0148] The switchable permanent - magnet assembly 300 includes an upper assembly 312 and a lower platter 314. The assemblies 312 and 314 each include a plurality of spaced - apart permanent magnets 330 and a plurality of pole portions 350. Each of the plurality of spaced - apart permanent magnets 330 is illustrated as a single permanent magnet in the figure, but may consist of a plurality of permanent magnets and / or at least one permanent magnet positioned within the housing.

[0149] Each permanent magnet 330 has an N - pole side (N) and an S - pole side (S). The permanent magnets 330 and the pole portions 350 of the assemblies 312 and 314 are arranged such that one of the pole portions 350 forms a closed shape positioned between two of the permanent magnets 330, respectively. Further, the permanent magnets 330 are arranged such that the two permanent magnets 330 in contact with the intermediate pole portion 350 each bring their N - pole side (N) or their S - pole side (S) into contact with the pole portion 350. When the N - pole side (N) of an adjacent permanent magnet 330 is in contact with the pole portion 350, the pole portion 350 is called an N - pole portion. When the S - pole side (S) of an adjacent permanent magnet 330 is in contact with the pole portion 350, the pole portion 350 is called an S - pole portion.

[0150] In the embodiment, the lower assembly 314 is held in a stationary state with respect to the housing enclosing the lower assembly 314, similar to the magnet 30 of the tool 10, and the upper assembly 312 rotates with respect to the lower assembly 314, similar to the magnet 32 of the tool 10. The upper assembly 312 is translatable with respect to the lower assembly 314 in directions 390 and 392, thereby changing the alignment of the permanent magnets 330 and the pole portions 350 of the upper assembly 312 with respect to the permanent magnets 330 and the pole portions 350 of the lower assembly 314. The permanent magnets 330 of the lower assembly 312 are spaced apart from the workpiece 17 by the pole shoe 340 being coupled to the pole portion 350. Alternatively, the pole portion may be extended to provide such a spacing. Further, a spacer (not shown) is provided between the permanent magnets of the upper assembly 312 and the permanent magnets of the lower assembly 314.

[0151] When the S - pole portion 350 of the lower assembly 314 is aligned with the S - pole portion 350 of the upper assembly 312, and the N - pole portion 350 of the lower assembly 314 is aligned with the N - pole portion 350 of the upper assembly 312 (see Fig. 20), the switching permanent - magnet assembly 300 is considered to be in the on state. In the on state, the workpiece 17 is held by the switching permanent - magnet assembly 300 due to the completion of the magnetic circuit from the aligned N - pole portions 350 of the upper assembly 312 and the lower assembly 314, through the workpiece 27, to the aligned S - pole portions 350 of the upper assembly 312 and the lower assembly 314.

[0152] When the S - pole portion 350 of the lower assembly 314 is aligned with the N - pole portion 350 of the upper assembly 312, and the N - pole portion 350 of the lower assembly 314 is aligned with the S - pole portion 350 of the upper assembly 312 (see Fig. 22), the switching permanent - magnet assembly 300 is considered to be in the off state. In the off state, the workpiece 17 is not held by the switching permanent - magnet assembly 300 due to the completion of the magnetic circuits within the upper assembly 312 and the lower assembly 314 from the aligned N - pole portion 350 of the upper assembly 312 to the S - pole portion 350 of the lower assembly 314 and from the aligned S - pole portion 350 of the upper assembly 312 to the N - pole portion 350 of the lower assembly 314.

[0153] When the S - pole portion 350 of the upper assembly 312 partially overlaps the N - pole portion 350 of the lower assembly 314, and the N - pole portion 350 of the upper assembly 312 partially overlaps the S - pole portion 350 of the lower assembly 314, the switching permanent - magnet assembly 300 is considered to be in a partial - on state. When in the partial - on state, the workpiece 17 can be held by the switching permanent - magnet assembly 300 due to the completion of the magnetic circuit from the overlapping N - pole portions 350 of the upper assembly 312 and the lower assembly 314, through the workpiece 17, to the overlapping S - pole portions 350 of the upper assembly 312 and the lower assembly 314. The strength of the magnetic circuit increases as the degree of overlap of the overlapping N - pole portions 350 of the upper assembly 312 and the lower assembly 314, and the overlapping S - pole portions 350 of the upper assembly 312 and the lower assembly 314 increases.

[0154] Furthermore, sensor 98 may be positioned adjacent to various ones of the N - pole portions 350 and S - pole portions 350. In an embodiment, at least one of the N - pole portions 350 and at least one of the S - pole portions 350 have an associated sensor 98, thereby monitoring the leakage magnetic flux associated with each N - pole portion and each S - pole portion. As shown in FIG. 31, the first sensor 98 may be disposed in proximity to the N - pole portion 350, for example, directly above the N - pole portion 350 or radially outside the N - pole portion 350, and the second sensor 98 may be disposed in proximity to the S - pole portion 350, for example, directly above the S - pole portion 350 or radially outside the S - pole portion 350. The logic control circuit 23 may perform calibration trials with respect to the permanent magnet assembly 300 in a manner similar to that described herein with respect to the magnetic coupling device 10, thereby storing sensor values for determining the operating state of the device including the permanent magnet assembly 300.

[0155] Referring to FIGS. 8 - 12, in an embodiment, the magnetic coupling tool 10 includes a demagnetization function for removing residual magnetism following the handling of the workpiece using the magnetic coupling tool 10.

[0156] In one exemplary embodiment, the magnetic coupling device 10 includes: an on / off switchable dipole flux source 15; a first housing component 22 that receives the flux source 15; and a pair of pole extension shoes 38 each having a workpiece engagement surface 44. The pole extension shoes 38 are installed in the first housing component 22, thereby receiving flux from the flux source 15 and making the flux available at the workpiece engagement surface 44. At least one magnetic field sensor 98, but preferably a number of first magnetic field detection sensors equal to the number of the pole extension shoes and / or the workpiece engagement surfaces, is preferably arranged in proximity to a magnetic detection surface 46 at an end of a relevant one of the pole extension shoes, opposite the workpiece engagement surface 44, while being spaced apart from the magnetic detection surface 46 by a predetermined distance. A pair of demagnetizing electric windings 110, each wound around a relevant section of one of the two pole extension shoes 38, is provided. The logic control circuit 23 is further operable to: (i) receive an output signal from the at least one magnetic field detection sensor and determine the operating state of the tool indicating that the flux source is switched off from the one or more output signals; (ii) turn on the power supply to the demagnetizing electric windings at this time; and (iii) perform a demagnetization cycle in which the demagnetizing electric windings generate an oscillating alternating magnetic field over a predetermined period of time.

[0157] In an embodiment, the demagnetizing electric winding 110 and the replaceable pole extension shoe member 38 form a modular unit attachable to the first housing component 22. The pole extension shoe member 38 forms part of the flux delivery circuit of the EOAMT 10 when used in magnetically coupling the EOAMT 10 to the workpiece 17, and also forms part of an electromagnet that performs a demagnetization operation during demagnetization of the workpiece 17, together with the demagnetizing winding 110.

[0158] In the embodiment, the logic control circuit 23 is designed such that a demagnetization cycle is performed immediately before the workpiece 17 handled by the magnetic coupling device 10 is removed from the magnetic coupling device 10, that is, when the magnetic coupling device 10 is stationary with the workpiece engaging surface 44 in contact with the workpiece 17 and the magnetic flux source 15 is turned off to release the coupling. By performing the demagnetization cycle at such a stage, the pole shoe 38 of the magnetic coupling device 10 functions as a conduit for concentrating the demagnetization operation on the workpiece region that will first exhibit magnetic remanence after the magnetic coupling device 10 is turned off.

[0159] In the embodiment, the pole extension shoe 38 consists of at least two components, namely a first pole extension member 38a detachably fixed to the first housing component, and a second pole extension member 38b detachably fixed to the extension of the first member and defining the workpiece engaging surface 44. Here, the demagnetizing electric winding 110 surrounds a section of the second pole extension member 38b. With this two-component type pole shoe layout, the EOAMT 10 can be provided with a demagnetization function, or it can be provided without a demagnetization function by simply decoupling the second pole extension member 38b from the first pole extension member 38a. In the latter case, the first pole shoe member 38a will present / provide the workpiece engaging surface 44. Similarly, this allows the second pole extension member 38b to be replaceable in order to provide a workpiece engaging surface 44 optimized for the geometry of the workpiece 17.

[0160] In an embodiment, the pole shoe 38 has a cross-section sufficient to direct most, preferably all, of the magnetic flux generated when the demagnetizing winding 110 is excited, in the section covered by the demagnetizing winding 110, towards the workpiece engagement surface 44. Thereby, it is ensured that all the magnetic flux supplied by the demagnetizing winding 110 is effectively used for demagnetizing the workpiece 17 in the contact zone with the pole extension shoe 38. Of course, it is also possible that the pole shoe 38 has a cross-section sufficient to direct a major part (but not all) of the magnetic flux generated upon excitation, in the section covered by the demagnetizing winding 110, towards the workpiece engagement surface 44 and create a magnetic flux leakage around the workpiece engagement surface 44. This means assists in demagnetizing the zone outside the direct contact portion between the pole extension shoe and the workpiece.

[0161] In an embodiment, the logic control circuit 23 further includes an AC driver (hardware or software) for generating a pulse-width modulated (PWM) current, which is supplied to the demagnetizing winding 110 as will be described in more detail herein. Further, in an embodiment, there may be functional blocks of the logic control circuit 23 for performing the demagnetization cycle.

[0162] In an embodiment, the demagnetizing winding 110 wound around (i.e., surrounding) a section of the ferromagnetic pole extension shoe 38 effectively forms an electromagnet. The control circuit and the microprocessor of the logic control circuit 23 are configured to drive the electromagnet to alternate the polarity and magnitude below the pole shoe 38. The pole shoe 38 always has a magnetic field in the opposite direction during normal (coupled) use of the tool. For tools of different sizes, by changing the parameters of the electromagnet to correlate the intensity of the magnetic field with the intensity of the switchable permanent magnet provided in the magnetic coupling device 10, the residual magnetic field remaining in the workpiece is overcome without generating a new residual magnetic field.

[0163] The two electromagnets that implement the degaussing function can be controlled using a typical DC motor drive. To minimize the residual magnetism remaining in the workpiece 17, an alternating magnetic field with decreasing magnitude is used. This alternating magnetic field is controlled by a microcontroller (via a dedicated DC motor drive chip) using a pulse-width modulated (PWM) waveform and a direction pin. The direction pin alternates the direction of the current supplied to the degaussing winding (coil). The PWM waveform controls the actual magnetic field seen through the electromagnet.

[0164] There are a number of parameters that affect the PWM waveform and thus the magnetic field, such as frequency, duty ratio, and amplitude. Workpieces 17 with different geometric shapes and steel compositions require different parameters for proper degaussing. Thus, the control circuit can include a suitable memory bank for storing a predetermined parameter table accessible by a programmed microprocessor, or it can store customized data sampled during calibration trials where the parameters are cycled and changed, the measured residual magnetism of the workpiece, and a set of "optimal" parameters for the determined PWM waveform that achieves the desired degaussing level for a particular workpiece. Exemplary hardware circuits for implementing various forms of PWM drivers are provided in U.S. Patent No. 3,895,270 and U.S. Patent No. 4,384,313, although more general circuits coupled to a programmable microprocessor may also be employed.

[0165] Returning to the drawings, an exemplary embodiment is illustrated. Referring to FIGS. 8 - 11, an exemplary embodiment of a magnetic coupling device 10 including a degaussing function is illustrated. The pole shoe 38 includes a degaussing winding 110 wound around each pole shoe 38.

[0166] A multi-component type ferromagnetic pole extension shoe 38 is provided. The pole shoe 38 is installed on the widthwise concave side portion of the lower part of the housing 22 using a pair of fastening screws 40. The pole shoe 38 includes: a first member 38a that is basically in the shape of a rectangular parallelepiped, which has chamfered edges along its height, is installed on the widthwise side portion of the lower part of the housing 22, and complements the shape of the upper part of the housing 22; and a second member 38b in the shape of a rectangular plate that is fixed to the lower end portion of the upright shoe member 38a with a fastening screw 38c. Another shape of the pole shoe 38' may be used.

[0167] The pole extension shoe 38 defines a surface below each workpiece engaging surface 44 (i.e., in the second member 38b), and these workpiece engaging surfaces 44 are planar in the illustrated embodiment, but may have different geometries and / or be contoured to form a precise abutment against the curved or non-uniform target surface of the workpiece to be magnetically coupled and handled by the tool 10. The fitting of the pole shoe member 38a to the receiving portion defined in the lower part of the housing 22 is such that it minimizes or practically substantially avoids the air gap of the magnetic circuit. In other words, the thick widthwise portion of the wall of the housing 22 and the pole shoe 38' together form a magnetic flux path from the magnets 30, 32 to the upper axial end face of the housing 22 and the lower end of the pole shoe 38.

[0168] Referring to FIG. 11, an exploded view of the demagnetizing assembly 110 is shown. The demagnetizing assembly 110 includes a demagnetizing electric winding or coil 114, which is wound around a bobbin 112 and is provided with a two-wire ribbon cable 116 for connection to a control circuit as described below. The coil 114 and the bobbin 112 are received within an upper bobbin cover 118 made of non-ferromagnetic steel or other materials, and thus the ribbon cable 116 passes through an opening in the upper wall of the bobbin cover 118. A bottom bobbin cover 120 is fastened to the upper bobbin cover 118 by a fastener 122.

[0169] And the above-described pole extension shoe 38 of the switching permanent magnet unit 20 incorporates the rectangular parallelepiped pole shoe component 38a by sliding it through an appropriately corresponding opening in the center of the bottom bobbin cover 120, extending it through the bobbin 112, and protruding it through the complementary opening of the upper bobbin cover 118. The customizable pole shoe component 38b that provides the workpiece engagement surface 44 is already attached to the lower axial end of the pole shoe component 38a using the fastener 38c or can be fixed later and abuts against the lower bobbin cover plate 120. As described above, the pole extension shoe component 38a and the demagnetizing coil 114 provide a dedicated electromagnet for performing the demagnetization cycle.

[0170] Referring now to FIG. 10, each of the two-wire ribbon cables 116 is routed through a dedicated demagnetizing wiring bore 124 that extends through the upper portion of the housing 22 on the widthwise side of the cylindrical bore 24. Subsequently, the two demagnetizing modules 110 are attached to the housing 22 of the switching magnet unit 20 by the above-described fastening bolts 40, and thereby the pole extension shoe 38 is fixed to the unit 22, completing the switching magnetic flux source used in the normal operation of the tool 10 for attachment to the workpiece.

[0171] The logic control circuit 23, particularly the main PCB 92, incorporates the hardware and software necessary to operate the demagnetizing module 110, particularly to generate (and control the waveform of) the demagnetizing AC sent through the demagnetizing coil 114. The two-wire ribbon cable 116 of the demagnetizing module 110 is attached to the socket of the pole substrate PCB 94 connected to the main control substrate PCB 92 via the inter-board connectors 102, 104.

[0172] The current flowing through the ribbon cable 116 to the coil 114 (which, when PWM modulated, may also be appropriately described as an operating signal for the degaussing coil 114) is controlled by the microcontroller and motor driver on the main control PCB 92. These signals are controlled by the PWM waveform from the microcontroller and provide a high-frequency AC signal. The degaussing PWM and direction pins operate by alternating positive / negative between the N and S poles and reducing the magnitude of each cycle. Depending on the material composition and geometric shape of the workpiece to be degaussed, it is necessary to change a plurality of different waveform parameters including frequency, magnitude, and shape, but not limited thereto.

[0173] The PWM signal effectively forms a degaussing circuit that changes rapidly with the workpiece and eliminates residual magnetism. An exemplary process is disclosed herein.

[0174] Regarding the degaussing coil 114, the wire gauge, length, and number of turns (and how far these windings are from the pole extension shoe (or the core of the electromagnet)) affect the inductance and resistance of the coil. Changes in inductance and resistance affect the coil's rise time, which means that different coils (different-sized units) require different series of PWM waveforms. By calculating the ideal rise time, the appropriate frequency can be determined. Generally, the larger the degaussing unit, the greater the mass of the coil required, which increases the rise time, i.e., the larger the unit, the longer it takes to degauss.

[0175] The way the coil is wound also affects the inductance and resistance of the coil. When the coil is wound in series, the resistance is approximately twice that of the parallel case. Therefore, the way the coil is wound also affects the PWM waveform.

[0176] In the embodiment, the logic control circuit 23 changes the operation of the demagnetization coil 114 using five parameters. These parameters include the following: (a) Prescaler: The prescaler divides the counter clock frequency from the main clock of the STM32F030R8T6 on the main PCB board. 240 is the standard used for consistency (when the period is set to 200, the frequency of each pulse is 1 kHz); (b) Period: The period of each individual pulse (when the prescaler is set to 240, 1 unit = 5 μs, a positive integer); (c) Step: The number of pulses at each amplitude (a positive integer); (d) Cycle: The number of amplitudes used for demagnetization (a positive integer); and (e) Amplitude: The maximum duty ratio used for demagnetization (floating, 0 < x < 1).

[0177] An exemplary demagnetization waveform is shown in FIG. 12. Note that the step function can be replaced with other types of functions that attempt to better mimic the sine wave. The following is a list of the parameters used to generate the waveform in FIG. 12: (a) Period: 10 (when the prescaler is set to 240, 1 hour unit in this graph = 5 μs); (b) Step: 3 (note that there are 3 positive steps and 3 negative steps per cycle); (c) Cycle: 3 (note that the waveform goes from positive to negative a total of 3 times. Also note that the number of cycles is equal to the number of different magnitudes); (d) Amplitude: 0.9 (note that the maximum duty ratio is 0.9 and the average waveform magnitude is equal to the duty ratio / amplitude. Also, the magnitude is determined by dividing the maximum amplitude by the number of cycles, 0.9 / 3 = 0.3 (first cycle = ±0.9; second cycle = ±0.6; and third cycle = ±0.3)).

[0178] By performing calibration trials while changing the above parameters, the efficiency and effectiveness of the demagnetization of the magnetic coupling tool 10 can be optimized. For example, the following table was created using data obtained with a prototype coupling tool with a demagnetization function based on the Magswitch AR70 unit. This table compares the performance of different software parameters and the observed maximum residual Gauss levels. This data was obtained for 51200 steel, which is known to retain residual magnetism. This data was obtained with the prescaler set to 240.

[0179]

Table 1

[0180] The number of steps per cycle was twice as high in the first test compared to the second and third tests. The first test had a relatively small residual, so the rise for the second and third tests was not long enough (the number of steps is directly related to the rise).

[0181] Using different types of flux units, namely the Magswitch J50 unit with a demagnetization function, Various tests were conducted to demonstrate the importance of conducting calibration tests in determining the best demagnetization results for a given workpiece.

[0182] The following software parameters were used to generate the PWM signal supplied to the demagnetizing coil: prescaler: 240; period: 250; step: 10; cycle: 20; and amplitude: 0.7. With these parameters, the demagnetization cycle took approximately 200 ms, and the maximum current consumption of the coil was approximately 0.9 A. For this unit, the coils were wound in parallel. The total resistance of the coils was approximately 8 Ω.

[0183] When the parameters change, different results can be observed. Using the following software parameters, a PWM signal was generated for the demagnetization coil for the second test: Prescaler: 240; Period: 300; Step: 10; Cycle: 20; and Amplitude: 0.7. With these parameters, it took approximately 200 ms for the demagnetization cycle, and the maximum current consumption of the coil was approximately 0.3 A. For this unit, the coils were wound in series. The total resistance of the coils was approximately 30 Ω.

[0184] After testing a number of other parameters, these were narrowed down. Initially, the number of steps was much higher, but this generated a more persistent magnetic field, which had an adverse effect on demagnetization. Initially, the number of cycles was much lower, but reducing the number of steps made it possible to increase the number of cycles while maintaining the demagnetization cycle below 0.5 seconds. Initially, the amplitude was high, but increasing the frequency of this unit presented a problem with the limit of the transistor switching speed.

[0185] It should be understood that the data provided above is based on the development of a prototype, and through optimization, an acceptable demagnetization cycle time can be obtained in the handling of workpieces by the robot.

[0186] Referring to FIG. 24, the functional processing sequence 600 of the logic control circuit 23 is shown. The above processing sequence includes various steps programmed such that the software of the tool starts when adopting the first four calibration processes of the tool for a given workpiece 17 (compared to the three steps outlined above); and steps performed when determining various states of the tool that may occur in the interaction with the workpiece 17 based on the comparison between the actual sensor data and the calibrated threshold sensor data (average). The tool 10 executes a start routine as represented by block 602. As represented by block 604, a check is made to confirm whether the demagnetization input of the input device 41 has been triggered. If triggered, as represented by block 606, a check is made to determine whether the magnetic flux source 15 is in the off state. If in the off state, a demagnetization cycle is performed as represented by block 608.

[0187] If the demagnetization input has not been triggered, as represented by block 610, a check is made to confirm whether the calibration input of the input device 41 has been triggered. If triggered, as represented by block 612, a four-step calibration attempt is performed. In one example, the magnetic coupling device 10 is calibrated for a single sheet thickness (1 mm) of a small square (100 mm × 100 mm). Two limit positions are calibrated with respect to the position of the magnetic coupling device 10 near the center of the sheet. The N-pole signal is calibrated with respect to the state where the N-pole shoe is at the edge (not the corner) of the sheet, and the S-pole signal is calibrated with respect to the state where the S-pole shoe is at the edge (not the corner) of the sheet.

[0188] If the calibration input is not triggered, the sensor values for the magnetic sensors 98 are averaged as represented by block 614. In one example, block 614 involves sampling the magnetic flux data points within a predetermined (very short) measurement period for each sensor 98, averaging the magnetic field sensor values of the tool, and processing these signals by the on-board processor of the magnetic field sensor - sensor signal processing circuit unit, all of which can be performed in a few milliseconds. Naturally, this increases the accuracy of data sampling and the performance of a series of sensors of the tool in determining different multiple tool states.

[0189] As represented by block 616, a check is performed to determine whether the sampled value indicates that the magnetic flux unit 15 is in the on state (or a calibrated partial on state). If it is not in the on state, it is determined that the magnetic flux circuit is off as represented by block 618. If it is in the on state, it is indicated that the magnetic flux circuit is on as represented by block 620.

[0190] Next, as represented by block 622, the averaged sensor values of the magnetic sensors related to the N - pole shoe and the sensor values of the magnetic sensors related to the S - pole shoe are checked to confirm that they are within the range of the calibrated values of limit position 1 and limit position 2. In the above - mentioned small and thin plate, the magnetic flux sensor values start to change rapidly when the magnetic coupling device moves away from the center of the plate. If both of the above are within the range, it is determined that a certain component exists and is within the target zone as represented by block 624. If it is not within the range, as represented by blocks 626 - 638, the magnetic flux sensor values for each magnetic sensor 98 are compared with the calibration values for each pole position to determine whether the N - pole or S - pole is on the component.

[0191] In one embodiment, a six-step calibration procedure is implemented. The following sensor values are calibrated: (1) limit position 1, N pole, best flux circuit; (2) limit position 1, S pole, best flux circuit; (3) limit position 2, N pole, worst flux circuit; (4) limit position 2, S pole, worst flux circuit; (5) S pole position; and (6) N pole position. This calibration procedure differs from the four-step calibration sequence described above in that the limit positions correspond to the corners of the sheet. In this procedure, the magnetic coupling device 10 is within the limit range as long as both the N pole shoe and the S pole shoe are on the sheet. For sensor values (1) and (2), the magnetic coupling device 10 is placed at the center of the sheet and these values are recorded. For sensor value (3), the magnetic coupling device 10 is placed with the N pole shoe adjacent to two edges of the sheet (at the corner), and the value for the N pole shoe sensor is recorded. For sensor value (4), the magnetic coupling device 10 is placed with the S pole shoe adjacent to two edges of the sheet (at the corner), and the value for the S pole shoe sensor is recorded. Sensor values (5) and (6) are the same as sensor values (3) and (4) in one example where the limit range is the entire sheet. If the sensor values for (3) and (4) are for positions that are not at the corners of the sheet, then sensor values (5) and (6) are obtained with the magnetic coupling device at the corners of the sheet, so sensor values (5) and (6) are different from (3) and (4). Referring to FIG. 25, an exemplary robot system 700 is shown. The embodiments described in connection with the robot system 700 may also be applied to other types of machines (such as mechanical gantries, crane hoists, lifting and placement machines, etc.).

[0192] The robot system 700 includes an electronic controller 700. The electronic controller 770 includes additional logic stored in an associated memory 774 for execution by a processor 772. A robot motion module 702 is included, which controls the motion of a robot arm 704. In the illustrated embodiment, the robot arm 704 includes a first arm segment 706, which is rotatable relative to a base about a vertical axis. The first arm segment 706 is movably coupled to a second arm segment 708 via a first joint 710, at which the second arm segment 708 may rotate in a first direction relative to the first arm segment 706. The second arm segment 708 is movably coupled to a third arm segment 711 via a second joint 712, at which the third arm segment 711 may rotate in a second direction relative to the second arm segment 708. The third arm segment 711 is movably coupled to a fourth arm segment 714 via a third joint 716, at which the fourth arm segment 714 may rotate in a third direction relative to the third arm segment 711, and the third arm segment 711 is movably coupled to the fourth arm segment 714 via a rotational joint 718, whereby the orientation of the fourth arm segment 714 relative to the third arm segment 711 can be changed. A magnetic coupling device 10 is illustrated as being fixed to the end of the robot arm 704 in the figure. The magnetic coupling device 10 is used to couple a workpiece 17 (not shown) to the robot arm 704. Although the magnetic coupling device 10 is illustrated, any of the magnetic coupling devices described herein, and any number of the magnetic coupling devices described herein, may be used with the robot system 700.

[0193] In one embodiment, an electronic controller 770 that executes a robot motion module 702 by a processor 772 moves a robot arm 704 to a first stop position, where the magnetic coupling device 10 contacts a workpiece. The electronic controller 770 that executes a magnetic coupler state module 776 by the processor 772 commands the magnetic device 10 to couple the workpiece to the robot system 700 by moving an upper magnet 32 relative to a lower magnet 30 to set the magnetic coupling device 10 to one of an on state or a partially on state. In an embodiment, the magnetic coupler state module 776 includes the function of a logic control circuit 23. Accordingly, the function of the logic control circuit 23 can be arranged either within the tool 10 or separated from the tool 10. The electronic controller 770 that executes a robot motion module 702 by the processor 772 moves the workpiece from the first position to a second desired spaced position. When the workpiece reaches the desired second position, the electronic controller 770 that executes a magnetic coupler state module 776 by the processor 772 commands the magnetic device 10 to decouple the workpiece from the robot system 700 by moving an upper magnet 12 relative to a lower magnet 14 to turn off the magnetic coupling device 10. The electronic controller 770 then repeats this process to couple, move, and decouple another workpiece 17. In one embodiment, before moving away from the workpiece 17, the controller 770 commands the magnetic coupling device 10 to perform a demagnetization cycle.

[0194] In an embodiment, the magnetic coupling device 10 has an elongated housing for holding a plurality of magnetic flux sources 15 as a linear array. An exemplary device having a plurality of magnetic flux sources 15 is the LAY Series unit manufactured and sold by Magswitch Technology Inc. Referring to FIGS. 34 and 35, a magnetic coupling device 400 is shown. The magnetic coupling device 400 includes a housing 402 that encloses a plurality of magnetic flux sources 15, in the figure magnetic flux sources 15A - C. A pole extension shoe 404 is provided along the lower side of the housing 402. The relative position of the magnet 32 of each magnetic flux source 15 is controlled by an actuator 406. Each magnetic flux source 15 operates in the same manner as with respect to the magnetic coupling device 10 and can be in any one of an on state, an off state, and a partially on state.

[0195] Furthermore, the magnetic coupling device 400 includes a magnetic field sensor 98 positioned within the housing 402. The magnetic field sensor 98 is shown positioned near the pole shoes 404 of two of the magnetic flux sources 15, in the figure magnetic flux sources 15A and 15C. In an embodiment, the magnetic field sensor 98 is associated with only a single magnetic flux source 15 of the plurality of magnetic flux sources 15A - 15C. In an embodiment, the magnetic field sensor 98 is associated with each magnetic flux source 15 of the plurality of magnetic flux sources 15A - 15C. The logic control circuit 23 can determine the quality of the magnetic circuit formed by the workpiece engagement surface 444 of the pole shoe 404 and the workpiece 17, the proximity of the workpiece 17, or other operating states disclosed herein by monitoring the magnetic field sensor 98.

[0196] In an embodiment, the magnetic coupling device 10 has an elongated housing for holding a plurality of magnetic flux sources 15 as a circular array. An exemplary device having a plurality of magnetic flux sources 15 is the AY Series unit manufactured and sold by Magswitch Technology Inc. Referring to FIGS. 36 and 37, a magnetic coupling device 450 is shown. The magnetic coupling device 450 includes a housing 452 that supports a plurality of magnetic flux sources 15, each having a pair of workpiece engagement surfaces 454, in the figures, magnetic flux sources 15A - F. The relative positions of the magnets 32 of each magnetic flux source 15 are controlled by an actuator 456. Each magnetic flux source 15 operates such that a magnetic operating circuit is formed through the workpiece 17 therebetween. The operation of the magnetic coupling device 450 is described in further detail in U.S. Patent No. 9,484,137, the disclosure of which is hereby expressly incorporated by reference in its entirety into the present application.

[0197] Furthermore, the magnetic coupling device 450 includes a magnetic field sensor 98 positioned within the housing 452. In an embodiment, the magnetic field sensor 98 is positioned in a cylindrical protrusion 458 that extends downwardly from the lower surface 460 of the housing 452. In the illustrated embodiment, two magnetic sensors 98 are positioned in each protrusion 458, one positioned between magnetic flux source 15F and magnetic flux source 15A, and the other positioned between magnetic flux source 15C and magnetic flux source 15D. In an embodiment, the magnetic field sensor 98 is positioned in the protrusion 458 between any two of the magnetic flux sources. In an embodiment, the magnetic field sensor 98 is positioned in each protrusion between adjacent pairs of magnetic flux sources 15A - F along the diameter of the circular array. The logic control circuit 23 can determine the quality of the magnetic circuit formed by the workpiece engagement surfaces 454 of the magnetic flux sources 15A - F and the workpiece 17, the proximity of the workpiece 17, or other operating states disclosed herein by monitoring the magnetic field sensor 98.

[0198] Without departing from the scope of the present invention, various modifications and additions can be made to the above-described exemplary embodiments. For example, although the above embodiments refer to specific features, the scope of the present invention includes embodiments having different combinations of features and embodiments that do not include all of the above features. Therefore, the scope of the present invention is intended to include all such alternative forms, modifications, and variations within the scope of the claims, together with all of their equivalents.

Explanation of Signs

[0199] 10 Magnetic coupling tool, magnetic coupling device, arm tip magnetic coupling tool, EOAMT, magnetic coupling unit 11 Housing 12, 14 Fastening structure 15 Switchable magnetic flux source, on / off switchable magnetic flux source, switchable dipole permanent magnet unit 15A, 15B, 15C, 15D, 15E, 15F Magnetic flux source 16 Switchable permanent magnet assembly 17 Ferromagnetic workpiece 18 Second housing component, actuator - electronic sensor - feedback assembly 20 Switchable permanent magnet device, switchable permanent magnet unit 22 First housing component, steel housing 23 Logic control circuit 24 Central cylindrical bore, central bore 26 Web, web portion 27 Workpiece 29 Recess 30 First permanent magnet, lower magnet 31 Temperature sensor 32 Second permanent magnet 33 Memory 36 Hexagonal drive shaft insert 37 Lower side of housing component 22 38 Pole extension shoe, pole shoe, pole extension shoe member 38’ Pole shoe 38a First pole extension member, first pole shoe member, first member, pole shoe component 38b Second pole extension member, second member, pole shoe component 38c Fastening screw 39 Communication module 40 Bolt, fastening bolt 41 Input device 42 Locator pin 43 Output device 44 Workpiece engagement surface, working surface, workpiece contact interface 46 Magnetic flux detection surface 48 Housing assembly 50 Actuator housing part, lower housing part 52 Rectangular recess 54 Actuator, rotary actuator 56 Torque output shaft 59 Bore of the lower housing part 50 60 Threaded bore on the upper surface of the housing 22 64 Flag and hard stop 66 Intermediate housing part 68 Recess, rectangular through-passage 70 Cylindrical passage channel 72 Upper housing part 74 Cover plate 76 Fastening screw 78 Bore 80, 82 Threaded bore 84 Upper block part 90 Magnetic field sensor - sensor signal processing circuit unit 92 Main control PCB, main control board PCB 94 Magnetometer sensor PCB, pole substrate PCB 96 Leg part 98 Magnetic field sensor, magnetic flux detection sensor, magnetic flux sensor, magnetometer, Hall effect sensor 100 M12 electronic connector 102, 104 Inter-board connector 101 Left half of the magnetic coupling tool 10 The right half of the magnetic coupling tool 10 The front half of the magnetic coupling tool 10, M12 push screw connector 106 LED window The rear half of the magnetic coupling tool 10 The first part of the left half 101 Demagnetizing electric winding, demagnetizing winding, demagnetizing assembly, demagnetizing module The first part of the right half 103 Bobbin The second part of the left half 101 Demagnetizing electric winding, coil, demagnetizing coil The second part of the right half 103 Two-wire ribbon cable Upper bobbin cover Bottom bobbin cover, lower bobbin cover plate Target zone Fastener The first limit Demagnetizing wiring bore The right end of the workpiece 17 The second limit The left end of the workpiece 17 Output device Switchable permanent magnet assembly, permanent magnet system Upper platter Lower platter Cylindrical base component Central aperture Aperture extending in the radial direction Permanent magnet N-pole side S-pole side Radially inner side Radially outer side Upper part Pole part 290, 292 Directions Central axis Switchable permanent magnet assembly Upper assembly 312 Lower assembly 314 Permanent magnet 330 N - pole side S - pole side Pole extension member, pole shoe 340 Pole portion 350 Magnetic coupling device 400 Housing 402 Pole extension shoe, pole shoe 404 Actuator 406 Workpiece engaging surface 444 Magnetic coupling device 450 Housing 452 Workpiece engaging surface 454 Actuator 456 Cylindrical protrusion 458 Functional processing sequence 600 Robot system, robot device for material handling 700 Robot motion module 702 Robot arm 704 First arm segment 706 Second arm segment 708 First joint 710 Third arm segment 711 Second joint 712 Fourth arm segment 714 Third joint 716 Robot controller, electronic controller 770 Processor 772 Memory 774 Magnetic coupler state module 776

Claims

1. A method for determining at least one operating state of a magnetic coupling tool, comprising: The method comprises: Detecting a first magnetic flux associated with the north pole of a switchable magnetic flux source supported by a housing, the switchable magnetic flux source being magnetically coupled to a plurality of workpiece engagement surfaces including (i) a first workpiece engagement surface corresponding to the north pole of the switchable magnetic flux source and a second workpiece engagement surface corresponding to the south pole of the switchable magnetic flux source, (ii) a plurality of permanent magnets including a first permanent magnet and a second permanent magnet rotatable or movable relative to the first permanent magnet, and (iii) a first state in which a first level of magnetic flux is available at the plurality of workpiece engagement surfaces and a second state in which a second level of magnetic flux is available at the plurality of workpiece engagement surfaces, the second level being less than the first level, the first magnetic flux being detected towards a first side of the switchable magnetic flux source at a position away from the first workpiece engagement surface of the north pole of the switchable magnetic flux source, the first side including the first workpiece engagement surface; Detecting a second magnetic flux associated with the south pole of the switchable magnetic flux source, the second magnetic flux being detected towards a second side of the switchable magnetic flux source at a position away from the second workpiece engagement surface of the south pole of the switchable magnetic flux source, the second side being opposite to the first side and including the second workpiece engagement surface; and Determining whether the magnetic coupling tool is in a first operating state based on at least one of the detected first magnetic flux and the detected second magnetic flux. A method comprising the above steps.

2. The step of determining the first operating state of the magnetic coupling tool comprises: Determining whether the detected first magnetic flux meets a first criterion; Determining whether the detected second magnetic flux meets a second criterion; and Determining that the magnetic coupling tool is in the first operating state when the detected first magnetic flux satisfies a first criterion and the detected second magnetic flux satisfies a second criterion The method according to claim 1, comprising: **Claim 3** The first criterion is that the output of the first magnetic field sensor is within a first range of magnetic flux values, The second criterion is that the output of the second magnetic field sensor is within a second range of magnetic flux values, the method according to claim 2. **Claim 4** The first range of magnetic flux values includes a first limit value corresponding to the first workpiece engagement surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the first workpiece engagement surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece, the method according to claim 3. **Claim 5** The second range of magnetic flux values includes a first limit value corresponding to the second workpiece engagement surface positioned at a first limit position of the target zone with respect to the ferromagnetic workpiece, and a second limit value corresponding to the second workpiece engagement surface positioned at a second limit position of the target zone with respect to the ferromagnetic workpiece, the method according to claim 3. **Claim 6** The method according to claim 2, further comprising determining that the first side of the switchable magnetic flux source including the first workpiece engagement surface is positioned outside the target zone on the ferromagnetic workpiece when the second criterion is satisfied and the first criterion is not satisfied. **Claim 7** The method according to claim 2, further comprising determining that the second side of the switchable magnetic flux source including the second workpiece engagement surface is positioned outside the target zone on the ferromagnetic workpiece when the first criterion is satisfied and the second criterion is not satisfied. **Claim 8** The method according to claim 1, wherein the first operating state is a state in which the magnetic coupling tool is in an off state.

9. The method according to claim 8, wherein the step of determining whether the magnetic coupling tool is in the first operating state includes comparing an output of at least one of a plurality of magnetic field sensors with a first threshold value.

10. The method according to claim 1, wherein the first operating state is a state in which at least one of the plurality of workpiece engaging surfaces is close to a ferromagnetic workpiece.

11. The method according to claim 10, wherein the step of determining whether the magnetic coupling tool is in the first operating state includes comparing an output of at least one of a plurality of magnetic field sensors with a second threshold value stored in a memory accessible by a logic control circuit.

12. The method according to claim 1, further comprising the step of determining a distance between the first workpiece engaging surface and the ferromagnetic workpiece.

13. The method according to claim 1, further comprising the step of determining an orientation of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece.

14. The method according to claim 13, wherein the step of determining the orientation of the first workpiece engaging surface and the second workpiece engaging surface with respect to the ferromagnetic workpiece includes comparing an output of a first magnetic field sensor with an output of a second magnetic field sensor.

15. The method according to claim 14, wherein the first workpiece engaging surface and the second workpiece engaging surface of the magnetic coupling tool are substantially parallel to the ferromagnetic workpiece when the output of the first magnetic field sensor and the output of the second magnetic field sensor satisfy a first criterion.

16. The method according to claim 15, wherein the first criterion is that the difference between the output of the first magnetic field sensor and the output of the second magnetic field sensor is within a threshold value.

17. A method for determining at least one operating state of a magnetic coupling tool, comprising: The method comprises: Detecting a first magnetic flux associated with the N pole of a magnetic flux source supported by a housing, the magnetic flux source being magnetically coupled to (i) a first workpiece engagement surface corresponding to the N pole of the magnetic flux source and a second workpiece engagement surface corresponding to the S pole of the magnetic flux source, and including a plurality of workpiece engagement surfaces, and (ii) a first permanent magnet fixed to the housing, and the magnetic flux source being configurable to have a first state in which a first level of magnetic flux is available at the plurality of workpiece engagement surfaces and a second state in which a second level of magnetic flux smaller than the first level is available at the plurality of workpiece engagement surfaces, and having a plurality of magnets including a second permanent magnet, the first magnetic flux being detected at a position away from the first workpiece engagement surface of the N pole of the magnetic flux source and directed toward a first side of the magnetic flux source, the first side including the first workpiece engagement surface; Detecting a second magnetic flux associated with the S pole of the magnetic flux source, the second magnetic flux being detected at a position away from the second workpiece engagement surface of the S pole of the magnetic flux source and directed toward a second side of the magnetic flux source, the second side being opposite to the first side and including the second workpiece engagement surface; and Determining whether the magnetic coupling tool is in a first operating state based on at least one of the detected first magnetic flux and the detected second magnetic flux. A method comprising the steps of:

18. The method according to claim 17, wherein the second permanent magnet and the first permanent magnet are vertically stacked.

19. In the first state, the N pole of the second permanent magnet is aligned with the N pole of the first permanent magnet, and the S pole of the second permanent magnet is aligned with the S pole of the first permanent magnet. In the second state, the N pole of the second permanent magnet is not aligned with the N pole of the first permanent magnet, and the S pole of the second permanent magnet is not aligned with the S pole of the first permanent magnet. The method according to claim 17.

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