816 results about "Magnet coil" patented technology

The invention discloses a hydraulic mechanism for a water-cooled magnet structure with high mechanical stability. The hydraulic mechanism comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a limiting block, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column. The water-cooled magnet has the advantages that axial stress application can be carried out on the magnet coil assembly, the pressing force on the magnet coil assembly is improved, the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved, and the high mechanical stability of the water-cooled magnet is improved.

The pressure release valve comprises a shell and a fixing sleeve arranged on the shell, an installation cavity is formed in the shell, an electromagnetic coil assembly is arranged in the installation cavity, the magnetic isolation sleeve is inserted in the installation cavity, the magnetic isolation sleeve is connected between the shell and the fixing sleeve in an abutting mode and isolates the installation cavity, and the electromagnetic coil assembly is arranged in the magnetic isolation sleeve. A movable valve element is arranged on the magnetism isolating sleeve in a sliding mode, and the end of the movable valve element is connected with a sealing piece.

The invention discloses an internally-inserted water-cooled magnet device for a high-field hybrid magnet. The internally-inserted water-cooled magnet device comprises a container assembly and a magnet coil assembly arranged in the container assembly. The container assembly comprises an upper barrel assembly, a container end cover, a hydraulic machine assembly, a center pipe assembly, an inner supporting assembly, a middle barrel assembly, a lower barrel assembly and an electric connecting assembly. The hydraulic machine assembly comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column. The axial force application device has the advantages that axial force application can be performed on the magnet coil assembly, the pressing force on the magnet coil assembly is improved, and the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved.

The invention discloses a novel internally-inserted water-cooled magnet container assembly for a hybrid magnet with high mechanical stability, which comprises an upper cylinder component, a container end cover, a hydraulic machine component, a central tube component, an inner support component, a middle cylinder component, a lower cylinder component, an electric connection component and a first conductive flexible connector, and a magnet coil assembly comprises a plurality of radially-sleeved coils; the hydraulic machine assembly comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a limiting block, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column. The device has the advantages that axial force application can be performed on the magnet coil assembly, the pressing force on the magnet coil assembly is increased, the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved, the dismounting and maintenance process of the mixed internally-inserted water-cooled magnet device is simple and rapid, and the efficiency is high. And the dismounting efficiency is improved.

The invention discloses a magnetron sputtering coating method with uniform coating and high target material utilization rate, and belongs to the technical field of film preparation, and the method realizes high-precision coating through whole-process collaborative optimization of pretreatment, sputtering, deposition and post-treatment. The substrate is cleaned in cooperation with radio-frequency pulse focusing bombardment; an electromagnetic coil group containing a temperature compensation coil is used for target sputtering, a magnetic field is dynamically adjusted in combination with laser profile sensing and a PID self-adaptive algorithm, and a direct current pulse-radio frequency composite power supply is matched to solve the target problem; in the deposition stage, a quartz crystal instrument is used for closed-loop film thickness control, metal film pulse gas supply and compound film reaction gas phase adjustment; gradient temperature rise is carried out according to data of an X-ray stress meter in post-treatment, and argon is used for dynamic protection and impurity prevention. According to the magnetron sputtering coating method with uniform coating and high target material utilization rate, the uniformity of coating and the target material utilization rate are improved, and the technological adaptability and stability of coating are improved.

The invention relates to the technical field of electronic circuits, in particular to a polar field magnet coil power supply system and a power supply method. The polar field magnet coil power supply system comprises a super capacitor, a control module and a driving module. The control module is coupled with the driving module and the polar field magnet coil, and the control module is configured to obtain feedback current of the polar field magnet coil, generate a first pulse width modulation signal group and generate a second pulse width modulation signal group. And the driving module is configured to respond to the first pulse width modulation signal group and generate the second pulse width modulation signal group, transmit energy stored by the super capacitor to the polar field magnet coil in the current rising sub-stage and the current maintaining sub-stage, and feed back the energy of the polar field magnet coil to the super capacitor in the current feedback sub-stage. According to the polar field magnet coil power supply system, the energy utilization rate can be greatly improved, the problem that energy cannot be recycled in the prior art is solved, and the problem that the failure rate is high is solved.

The invention relates to the technical field of vehicle-mounted visual perception, in particular to a camera active anti-shake cooling system based on a magnetorheological fluid medium and a control method. The heat dissipation system comprises a camera module, at least three independent pipelines which are arranged around the camera module and are hollow inside, a hydraulic driving unit, at least one electromagnetic coil which is arranged on the outer wall of the independent pipeline and is used for generating a controllable magnetic field, and a controller, the controller is used for cooperatively controlling the liquid pressure in the pipeline and the magnetic field intensity acting on the magnetorheological fluid according to the vehicle state information and / or the posture information of the camera module so as to achieve active anti-shake and heat dissipation of the camera module. The pressure of the cooling liquid in the pipeline is adjusted to support the camera and change the electromagnetic force between the magnetic fluid and the coil by changing the magnetic field intensity, and lens shaking is reduced in cooperation with a vehicle body active shock absorption system.

The utility model discloses an electromagnetic coil, a magneto-rheological shock absorber and an automobile. The electromagnetic coil comprises an iron core and an excitation wire. The iron core is sleeved outside the sliding end, and a wire slot is annularly formed in the peripheral side of the iron core; the excitation wire is wound in the wire slot to form an excitation coil, and the cross section of the excitation wire is in a flat geometric shape; the magnetorheological damper comprises the electromagnetic coil and is applied to an automobile. In the scheme of the utility model, after the excitation lead is wound into the excitation coil, the gap between each turn of lead and the gap between the external lead of the excitation coil and the slot wall of the wire slot are greatly reduced, under the condition that the space of the wire slot is not changed, the number of turns of the coil can be increased by using the flat excitation lead, and the utilization rate of the space in the wire slot is higher; the effective working length of the electromagnetic coil is larger, the maximum damping force of the magneto-rheological shock absorber can be improved, the electromagnetic efficiency is greatly improved, and large damping force can be generated only through small current.

The invention relates to a seabed trapezoidal foldable electromagnetic coil device, which belongs to the technical field of ocean electromagnetic detection and comprises a main bearing beam, an expandable transmitting coil assembly, a receiving coil assembly, a transmission connecting rod, a hinged rotating seat, a sliding connecting seat and a push-pull driving rod. The transmitting coil is of a symmetrically-distributed trapezoidal structure, the receiving coil is in sliding fit with the main bearing beam through the sliding connecting base, the push-pull driving rod is in linkage with the receiving coil to move and the transmitting coil to be unfolded / folded, the device frame is made of a macromolecule non-magnetic material, and the ferromagnetic driving component is arranged in an avoiding mode. Receiving coil plane magnetic field balance is achieved through the non-uniform magnetic field design of the trapezoidal transmitting coil, coil space optimization configuration is completed through a linkage mechanism, folding portability and anti-interference performance of a multi-layer coil are achieved at the same time, direct coupling of a primary field of the transmitting coil to receiving is effectively restrained, the stability and the signal-to-noise ratio of a detection signal are improved, and the detection precision is improved. The method is suitable for complex seabed transient electromagnetic detection scenes carried by AUV / ROV.

The invention discloses a fusion device magnet coil copper conductor nondestructive testing method and a computer product, and relates to the technical field of nondestructive testing, the method comprises the following steps: obtaining original eddy current testing signals of a to-be-tested object or a plurality of areas of the to-be-tested object under specific physical conditions; preprocessing the original eddy current detection signal, wherein the preprocessing comprises denoising and signal correction; extracting features from the preprocessed signals and carrying out normalization processing; on the basis of a pre-established multi-parameter model related to the physical conditions of the to-be-tested object, theoretical signals of the to-be-tested object under various physical conditions are predicted through finite element simulation; and performing matching estimation on the normalized signal and a theoretical signal to obtain an estimated signal, and evaluating the defect existence probability based on the estimated signal. Based on an eddy current testing technology, a probe scans a sample and obtains a signal, and a finite element analysis method is combined to simulate and evaluate defects such as cracks possibly existing in a material.

The invention discloses a fuzzy neural network-based intelligent tension control method and system for a plateau tunnel pre-stressed anchor rod, and the system is characterized in that a free section of the anchor rod is sleeved with a negative Poisson ratio outer sleeve, a magneto-rheological regulation and control cavity is formed in the anchor rod, magneto-rheological fluid is injected into the magneto-rheological regulation and control cavity, and a friction power generation-sensing assembly is mounted at the tail end of the anchor rod; therefore, the anchor rod unit integrating friction increase along with the load, adjustable damping and self-energized sensing is formed. In the tensioning process, the friction power generation-sensing assembly is used for measuring the elongation of the anchor rod and providing self-powered energy, the pressure of a magneto-rheological regulation and control cavity and the displacement of a piston are collected, a state vector containing design prestress, the elongation, equivalent damping force and environment vibration indexes is constructed and input into a fuzzy neural network controller, and the state vector is calculated. The expansion amount of the hydraulic jack and the current of the electromagnetic coil are output, and intelligent application, dynamic compensation and long-term monitoring of prestress of the anchor rod group are achieved. Self-sensing, self-adaptive adjustment and active friction increasing of the pre-stressed anchor rod group can be achieved without an external power source.

The invention discloses a high-current-carrying water-cooling magnet coil combined structure which comprises a hydraulic machine assembly, a coil A and a coil B, wherein the coil A and the coil B are connected in series. The hydraulic machine assembly comprises a cylinder body, a piston, a check ring, a pressure equalizing pad, a limiting block, a first force transmission check ring, a first anti-rotation pin, a second force transmission check ring, a second anti-rotation pin, a first force transmission column and a second force transmission column, the coil A and the coil B are electrically connected in series through an AB electric connecting plate, the first force transmission column is in insulated connection with the AB electric connecting plate, and the second force transmission column is in insulated connection with the coil B; and the electromagnetic coil between the coil A and the coil B is insulated through an insulating cylinder assembly. The device has the advantages that axial force application can be performed on the magnet coil assembly, the pressing force on the magnet coil assembly is improved, and the problems of tension fracture and damage caused by coil stress overrun due to overlarge radial expansion electromagnetic force of a magnet coil bit piece and an insulating piece are solved; the structure of the insulating cylinder assembly realizes high current carrying of the A coil and improves the magnetic field intensity of the water-cooled magnet.

The invention provides an interference injection system for an automobile driving test, which comprises a test platform, an uphill plate, a downhill plate, a light-transmitting plate and an identification arrangement mechanism, and is characterized in that the identification arrangement mechanism comprises a lifting plate, an electric push rod, magnetorheological fluid, an electromagnetic coil, a reserve adjusting mechanism and a main control unit; and the main control unit can control the electromagnetic coils at different positions in the lifting plate to be electrified through the upper part of the light-transmitting plate, and the road sign is formed after the magnetorheological fluid at the upper part is gathered through the generated magnetic field, so that the identification capability of the automobile on the road sign can be tested, and the main control unit can test the identification capability of the automobile on the road sign by regulating and controlling the electrification of the electromagnetic coils. According to the invention, instantaneous switching of road sign interference is realized, and after the storage amount of the magnetorheological fluid is adjusted through the storage amount adjusting mechanism, the color of the road sign can be lightened when the road sign is generated, and the road sign worn by an external environment on a real road can be simulated, so that the performance of an automobile can be tested in an omnibearing manner.

The invention relates to the technical field of electronic circuits, in particular to a magnet coil power supply system, a control method and electronic equipment. The magnet coil power supply system comprises a subsystem and a control module. The subsystem comprises a plurality of sub-modules and a magnet coil sub-module; the plurality of sub-modules are arranged in an array in the form of M rows and N columns; the sub-module comprises a first capacitor and a driving module; the first capacitor is connected in parallel with the driving module; the control module is connected with the driving module; the control module is configured to generate M * N groups of driving pulse signals for the plurality of sub-modules by adopting a carrier phase-shifting modulation mode; for the ith row of sub-modules in the array, the corresponding driving pulse signals have the same phase offset relative to the driving pulse signals of the first row of sub-modules, and the offset of the phase offset is (i-1) / M carrier periods. The power supply voltage and the working current of the magnet coil can be greatly improved by arranging the plurality of sub-modules in an array, and current ripples can be reduced and the control efficiency can be improved by a phase shift control strategy.

Various embodiments of the teachings herein include a stator housing for an axial flux machine with a rotor to rotate about an axis of rotation, a stator spaced apart from the rotor along the axis of rotation, and a fluidtight interior space containing coil receiving locations in a circumferential direction around the axis of rotation to receive electromagnetic coil assemblies, wherein each coil assembly has at least one coil wound axially around a stator tooth. An example includes: a liquid cooling system having a first cooling channel extending circumferentially in the stator housing; and a second cooling channel separate from the first and extending circumferentially in the stator housing; wherein the interior space holds a cooling liquid in thermal contact with cooling liquid in the first and the second cooling channel.

The invention discloses a novel water-cooled magnet coil end electromagnetic force control structure which comprises a coil A, a coil B, a coil C, a coil D, a coil E and a coil F. The coil A, the coil B, the coil C, the coil D, the coil E and the coil F are sequentially connected in series in a sleeving mode in the radial direction. The F coil comprises an F magnet coil, an F coil end plate, an F fixing rod, an F transition electric connecting ring, an F lower insulation supporting anti-rotation cylinder and a reinforcing rod. The coil assembly has the advantages that through the arrangement of the sectional insulating cylinder assembly, the insulating effect is achieved, the coil A is positioned instead of a fixing rod, the stability of the two ends of the F magnet coil is enhanced, the problems of movement and dislocation near an end plate during operation of the F coil are solved, and the service life of the F coil is prolonged. And the F transition electric connecting ring is prevented from being damaged under the condition of sudden power failure during operation of the mixed interpolation water-cooling magnet device.

The embodiment of the utility model provides an electromagnetic type nut conveying gun which comprises a material receiving seat assembly, a material conveying assembly and a material conveying assembly, wherein the rear end of the material receiving seat assembly is connected with a connector assembly; an electromagnetic coil is arranged in the connector assembly; the ejector rod assembly is connected to the rear end of the connector assembly and comprises an ejector rod protection sleeve and an ejector rod arranged in the ejector rod protection sleeve. The rear end of the ejector rod assembly is connected with an air cylinder. And a piston of the air cylinder is connected with the ejector rod, so that the top of the ejector rod can reach the interior of the material receiving seat assembly. A nut is attracted through an electromagnet, the problem that when a traditional nut conveying gun conveys the nut, the nut is pushed to the designated position through an air cylinder, and the nut cannot fall into the designated position easily is solved, and meanwhile the phenomenon that the nut is brought back and the conveying ejector rod is magnetized permanently due to different welded materials of a single-electromagnetic-coil nut conveying gun is avoided; and meanwhile, the nut conveying angle accuracy and speed of the nut conveying gun are improved.

The utility model relates to the technical field of valve maintenance equipment, in particular to a portable anti-explosion valve cleaning device, which is characterized in that the polarities of the opposite surfaces of two fixed magnetic field sources are the same, and a movable electromagnetic coil is arranged between the two fixed magnetic field sources; the control unit is used for periodically changing the polarity of current supplied to the movable electromagnetic coil and driving the movable electromagnetic coil to reciprocate, the plunger pump is provided with a grease inlet and a grease outlet, the grease outlet is used for being communicated with a valve to be cleaned, and the grease inlet is used for being communicated with a grease body box; according to the utility model, the electromagnetic driving mechanism is adopted to replace the existing manual driving, so that the pumping-out speed and the working efficiency of cleaning fluid or lubricating grease are improved, the maintenance operation time of a single valve is shortened, and operators are liberated from heavy repeated physical labor.

This invention provides a capacitive stylus and its usage method, belonging to the field of stylus technology. The capacitive stylus includes: a stylus shell; a pen tip installed in the lower part of the stylus shell; and an adjustment mechanism comprising a magnetorheological fluid cavity, a rotating sleeve, a guide groove, a connecting shaft, an electromagnetic coil, and a magnetic ring. Multiple guide grooves are provided, and two electromagnetic coils and two magnetic rings are provided. The magnetorheological fluid cavity is located in the upper part of the pen tip. By setting a magnetorheological fluid cavity, a rotating sleeve, and symmetrically arranged electromagnetic coils and magnetic rings within the pen tip, and utilizing the reversible viscosity change of the magnetorheological fluid under a magnetic field, stepless continuous adjustment of writing damping within the range of 10-150 mN·m is achieved. Users can freely adjust the pen tip rotation resistance according to personal preference or different writing scenarios, significantly improving the stylus's personalized adaptability and writing experience.

The invention relates to the technical field of electromagnetic coils, and discloses a laminated tooth-shaped coil winding based on interlayer phases and a design method of the laminated tooth-shaped coil winding. According to the tooth-shaped coil, the number of effective edges of the winding is remarkably increased through a multi-branch parallel connection mode, and the end portions are reduced; meanwhile, gaps of the concave tooth portion and the convex tooth portion of the tooth-shaped coil provide enough space for winding assemblies such as an iron core, a heat dissipation pipe, an insulating material, a structural material and a sensor, forming of an integrated winding with magnetism gathering, heat dissipation, insulation, structural strength and sensing control is facilitated, and application and popularization of the type of winding are greatly facilitated through the design method.

The utility model relates to the technical field of electromagnetic valves, and discloses an electromagnetic type gas emergency cut-off valve which comprises a valve body, a valve element assembly, an electromagnetic control assembly and a manual control rod, the valve body comprises a cavity and a partition body, the electromagnetic control assembly comprises an electromagnetic coil pipe and a magnet, the magnet slides in the electromagnetic coil pipe, and the manual control rod is arranged in the cavity. The magnet is fixed to the valve element assembly, the electromagnetic coil pipe is fixed to the interior of the shell, the shell is fixedly connected with the valve body, through the structural design of the manual control rod and the shell, the electromagnetic control assembly is prevented from being interfered by the manual control rod, and quick response of the electromagnetic control assembly can be guaranteed; when electric control is carried out through the electromagnetic control assembly, the manual control rod is completely in zero contact with the electromagnetic control assembly without interference, and the manual control rod can tightly press the valve element assembly through threaded connection between the manual control rod and the shell, so that a good sealing effect is achieved under manual control.

The invention discloses an electromagnetic capture connecting mechanism with a spring flexible support, and relates to the technical field of electromagnetic capture. The device comprises a base, an inner cavity of the base is fixedly connected with a fixing assembly, the inner cavity of the base is fixedly connected with a flexible supporting assembly through the fixing assembly, the top of the flexible supporting assembly is fixedly connected with an electromagnetic coil, and the flexible supporting assembly comprises a mounting boss fixedly connected to the top of the base. According to the supporting structure, rigid supporting is changed into elastic deformable supporting, the stress of the end face of the electromagnetic coil and the supporting piece is effectively reduced, meanwhile, the damping spring and the electromagnetic coil are integrally designed, the buffering function is added while the electromagnetic performance is kept unchanged, the fatigue life of the supporting piece is prolonged, and the service life is prolonged. The magnetic core and the butt joint face are kept coaxial through the elastic buffering effect, force-displacement coupling energy absorption is achieved at the same time, mechanical impact at the electromagnetic capture moment is avoided, relative vibration attenuation in the butt joint process is accelerated, and capture precision is improved.

The invention relates to the technical field of rehabilitation training equipment, and discloses a gynecological postpartum pelvic floor muscle rehabilitation training device based on pressure sensing, which comprises a training bed, the bottom of the training bed is fixedly connected with a supporting seat for supporting and fixing the training bed, and one side of the top of the training bed is provided with a positioning pillow for positioning the head of a user. By adding and arranging a dynamic adjusting mechanism, when a user carries out postpartum pelvic floor muscle rehabilitation training, the mechanism firstly collects pressure data in the training process in real time through a pressure sensor, precise regulation and control over the current intensity of an electromagnetic coil base are achieved in cooperation with a PID controller, and then the attaching number of magnetic particles in magnetic suspension is changed; and secondly, the dynamic adjustment mode can automatically adapt to training resistance according to muscle strength levels and rehabilitation stages of different lying-in women, the resistance of a person with weak muscle strength is reduced, muscle injury is avoided, and the problem that the fixed resistance of traditional equipment cannot be subjected to personalized adaptation is thoroughly solved.

The application discloses a kind of plasma propulsion devices, belong to plasma electric propulsion technical field, comprising: discharge chamber, spiral antenna I, center arc structure, spiral antenna II, center compensation structure, radio frequency power supply and electromagnetic coil;Center arc structure is located in discharge chamber, spiral antenna I spiral is wound in the outer wall of discharge chamber, with the position opposite of center arc structure;Center compensation structure is located in discharge chamber, spiral antenna II spiral is wound in the outer wall of discharge chamber, with the position opposite of center compensation structure;Spiral antenna I and spiral antenna II are electrically connected with radio frequency power supply respectively;Two electromagnetic coils are wound and set in the outer wall of discharge chamber, respectively located in the two ends of spiral antenna II;Center compensation structure can release neutral particles under the action of heat;The application can improve ion number density, realize high specific impulse output of propulsion device, improve propulsion efficiency.

A novel electromagnetic driving mechanism comprises at least one driving assembly, each driving assembly comprises a fixing base, a winding reel and a movable iron rod, the movable iron rods can be inserted into the fixing bases in a front-back moving mode, the winding reels are fixedly connected to the rear ends of the fixing bases, the rear portions of the movable iron rods are located in the winding reels, and the winding reels are fixedly connected to the rear ends of the fixing bases. The front end of the movable iron rod extends out of the front end of the fixing base, the front end of the movable iron rod is connected with a transmission assembly, and an electromagnetic coil is wound around the periphery of the winding reel and controlled by a controller. Compared with an existing electromagnetic driving mechanism, the electromagnetic driving mechanism is simpler in structure, the electromagnetic driving mechanism can be formed only through the electromagnetic coil, the movable iron rod and the transmission assembly, and meanwhile the manufacturing cost and the weight of the electromagnetic driving mechanism are reduced.

This invention relates to the field of energy storage technology for new energy power plants, and discloses a multi-compartment coordinated charging and discharging intelligent control device for a new energy power plant energy storage system. The device includes a container body, multiple battery clusters and a DC power control cabinet installed on its inner wall. The energy storage EMS energy management system host sends control commands to drive the drive module to synchronously energize electromagnetic coil one and electromagnetic coil two to generate a directional magnetic field. Electromagnetic coil one, in conjunction with a magnetically conductive shell, magnetizes the iron core. The iron core magnetically attracts the I-shaped armature to compress the spring one, which slides downward along the inner wall of the connecting cavity and pulls the telescopic partition to divide the upper part of the connecting cavity into independent positive and negative magnetorheological chambers that are not connected. The magnetorheological fluid in the liquid chamber flows into the corresponding chamber and, under the action of the magnetic field of electromagnetic coil two, transforms from a liquid state into a rigid solid-like state and forms a dense conductive chain, thereby forming a conductive path to ensure that the battery clusters can be independently switched on and off and coordinated across multiple compartments.

The application relates to the field of vibration reduction technology and discloses an active anti-vibration base and a mounting method thereof. Through cooperation of an electromagnetic coil and a magnet rod, the epoxy cover plate is pushed upward by the pushing force of the electromagnetic coil, so that a magnetic suspension support is formed to reduce vibration, the influence of external vibration on equipment can be reduced, and meanwhile, through cooperation of a piston pipe and a lifting piston, when the base vibrates, the external air is pumped into the air spring through the up-and-down vibration of the lifting piston, so that the pressure of the air spring is increased, the natural frequency of the system can be changed, the resonance frequency is avoided, and the influence of resonance is reduced.

The present application is drawn to a system and method, as well as method for manufacture of a device and system for determining the position and orientation of at least one magnetic field sensor comprising: a rigid structure comprising an array of at least five electromagnetic coils; at least one wire that connects to and powers the electromagnetic coils; wherein the placement and orientation of the electromagnetic coils on the rigid structure are predetermined; wherein the electromagnetic coils, each having a predefined magnetic moment per unit current, are constructed with a printed circuit board (PCB) comprising at least one conductive layer; and wherein the system is configured such that a stray magnetic field emanating from the at least one, as measured at the location of the at least one magnetic field sensor, generates substantially lower magnetic field intensity than that produced by each of the at least five electromagnetic coils.