GB2248006A

GB2248006A - A responsive robotic technique

Info

Publication number: GB2248006A
Application number: GB9108566A
Authority: GB
Inventors: Haqi Ismail Hussain Almossawi
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-04-25
Filing date: 1991-04-22
Publication date: 1992-03-18
Also published as: GB9108566D0

Abstract

Multiple magnetic fields are used to levitate and move a body (10) translationally and rotationally. The magnetic directions may be aligned with the crystallographic axes of the body (10). Applications to loudspeakers and accelerometers are disclosed. <IMAGE>

Description

A RESPONSIVE ROBOTIC TECHNIQUE Technical Field The present invention relates to magnetically responsive and transmittible robotic arrangements and to a method of operating such arrangements.

This invention also relates to 3D Active responsive or transmittible apparatus, and to a method of operating 3D responsive or transmittible apparatus.

Background The conventional accelerometers, geophones, speakers, or headphones are of a spring mass form, and in operation the case and magnet system vibrates with respect to the coil and induces a coil voltage proportional to the relative velocity,or vice versa. A geophone or speaker should have a constant amplitude and linear phase frequency response over the range of interest in order not to distort the relative phases of the incident or induced waves. It follows, therefore, in a spring mass system that the resonant frequency should be below the. lowest frequency of interest and that adequate damping should be provided.

The first is achieved by making the resonant frequency of the order of 1.0 to 10 Hz, and the second by using external damping resistors. A resonant frequency of the order of 1.0-10 Hz implies that the suspension is very compliant. The coil, therefore, sags and the geophone or speaker can be used solely in one position since only a small tilt of the coil with respect to the magnet gap can be tolerated. The methods available to manufacture the compliant suspension springs also lead to transverse or rotational resonances which are undesirably close to the frequency band of interest. Therefore, the conventional accelerometer, geophone, speaker, or headphone are strictly the one axis devices and they are frequently mounted in sets in order to receive or transmit data. To date there have been few attempts to change from passive to active robotic receivers or transmitters.For example,one attempt adds internal electronics to produce a magneto-dynamic velocity-nulling feedback system which lead to the moving coil moving little with respect to the housing and makes the output characteristics virtually independent of the springs. The device is improved, but it still has restricted frequency response, and the apparatus is only a one axis instrument. Another development which has taken place over the last few decades is the use of piezo-electric devices.

These have very good high frequency response such as is required for in-seam coal and other investigations. However, they are relatively fragile and expensive, they also require an expensive buffer or charge amplifier.

Works have been conducted for many years on magnetic material movable in electromagnetic fields. Multi axial accelerometers or speakers are available and require more than one proof mass or spring mass system, an example of such an accelerometer may be found in U.S. Pat. No. 3,710,629; and an example of the speaker may be found in GB Pat.No. 873,511. The single mass system of 3-axes accelerometers are disclosed in U.S. Pat. No. 3,280,641 and 3,680,392; or GB Pat.No. 1,472,995, PCT Pat.No. W084/00434 for the speakers. The U.S. Pat.No. 3,280,641 discloses an ultrasonic proof mass support and position readout, while U.S.

Pat. No. 3,680,392 utilises electrostatic sensing and mass support system. Other accelerometric components are shown in U.S. Pat. Nos. 3,823,990; 3,167,962; 3,293,920; 3,363,470; 3,961,536; and 3,973,442. In all cases, the accelerometers or speakers are not necessarily good vibration apparatus for the required frequency vibrations.

However, with the exception of the disclosure in U.S. Pat. No.

4,458,536, or U.S.Pat. No. 4,585,090 most of the prior arrangements have included a magnet piston which is able to slide to and from in a cylinder and in one direction only. In U.S.

Pat. No. 4,458,536 each end of the proof mass is held in separate complicated magnetic fields acting on the ends only with the x-axis suspension at each end comprising a stator 14 on the housing which surrounds the pole 8 on the mass, and the y-axis suspension being the mass as the x-axis suspension at each end, but turned through 90 degrees. In U.S. Pat. No.

4,585,090 an envelop of many discrete parts is driven by an internal driven element so that the parts of the envelope move alternatively in unison in an outwards direction and in unison in an inward direction, and inside the envelope is arranged a framework comprising of struts and tensile members and the envelope parts are mounted on these struts and tensile members. Operation of the driven element varies the distance between two parallel struts of the framework which is thus caused to distort and so cause the desired movement of the envelope parts.

The teaching of U.S. Pat.No. 4,458,536 is to provide separate supports at each end of the magnetic levitation system, and U.S. Pat. No. 4,458,536 would not be able to operate if the proof mass were to be enclosed within the field.

The present invention is based on the teaching of PCT Pat. No.

PCT/GB89/00571 (W089/11636), seeks to improve the present methods and apparatus. It provides a 3D apparatus, so that sixdegrees of freedom of 3-axes of translational and rotational motions are measured or transmitted by one levitated mass rather than by three separate devices using three different displaced masses. The nub of this invention is to use 3D magnetic levitation to levitate the mass rather than springs.

ESSENTIAL TECHNICAL FEATURES According to one aspect of the present invention, a magnetically responsive or transmittible arrangement including a levitated movable magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first magnetic field being arranged to act on opposed sides of the magnetic portion, that first field,when viewed from one direction, being arranged to be generated by four magnetically operable means located on a first side of the arrangement and four magnetically operable means located on an opposed second side of the arrangement, the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending parallel the directions in which the second magnetically operable means are arranged to exert a force on the magnetic portion along one axis, and enabling the electronics and arrangements to be triplicated for 3-axes of crystallographic system of operable geometry and proportional to the geometry of the levitated magnetic portion.

According to a second aspect of the present invention, a magnetically responsive or transmittible arrangement including a levitated movable magnetic portion arranged,in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first sensing field being arranged to act on opposed sides of the first magnetic portion, that first field, when viewed from one direction, being arranged to be generated by four sensing operable means attached to or spaced from four magnetically operable means located on a first side of the arrangement and four sensing means attached to or separated from four magnetically operable means located on an opposed second side of the arrangement, the sensing exerted on the magnetic portion by the first sensing operable means being arranged to act in a direction extending parallel the directions in which the second sensing operable means are arranged to exert a sensing on the magnetic portion along one axis, and enabling the electronics and arrangements to be triplicated for 3-axes of crystallographic system of operable geometry and proportional to the geometry of the levitated magnetic portion.

According to another aspect of the present invention, a magnetically responsive or transmittible arrangement including a levitated movable magnetic portion arranged,in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first magnetic field being arranged to act on opposed sides of the magnetic portion, that first field, when viewed from one direction, being arranged to be generated by a first magnetically operable means located on a first side of the arrangement and second and third magnetically operable means located on an opposed second side of the arrangement, the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the magnetic portion.

The first magnetically operable, or lifting, means may be arranged to act generally in the region of the centre of the first side, when viewed from the one direction.

The second and third magnetically operable means may be spaced from each other. The second and third magnetically operable means may be arranged to act on opposed sides of the centre of the second side.

The first, second and third magnetically, operable means may be arranged to be capable of causing translational movement of the magnetic portion in a transverse direction extending between the first and second sides. The first, second and third magnetically operable means may be capable of causing rotational movement of the magnetic means about an axis transverse to the extent between the second and third magnetically operable means.

Operation of one magnetically operable means may be capable of causing the relative translational or rotational movement of the magnetic portion.

At least one of the magnetically operable means may extend across a side of the magnetic portion.

The magnetic portion may include discrete magnetic regions located adjacent to each of the magnetically operable means.

At least one of the magnetic regions may comprise a generally flat region.

Sensing means may be included arranged to monitor the location or movement of the magnetic portion, the sensing means comprising a first sensor arrangement being located in the region of opposed sides of the magnetic portion and including a first sensor located in the region of one of the first or second sides of the arrangement and second and third sensors located in the region of the other of the first or second sides of the arrangement, the first sensor being located at an intermediate region along its associated side,when viewed from one direction and the second and third sensors being located at different regions along their associated side. The first sensor may be located generally in the region of the centre of its associated side. The second and third sensors may be spaced from each other.

The first sensor may be located in the region of the second side and the second and third sensors are located in the region of the first side. The second and third sensors may be located in the region of opposed sides of the sensor or their associated side.

The first, second and third sensors may be capable of sensing rotational movement of the levitated magnetic portion about an axis transverse to the extent between the first and second sides and transverse to the extent between the spaced second and third sensors.

The first sensor alone may be capable of sensing translational movement of the magnetic portion in the transverse direction.

The second and third sensors alone may be capable of sensing rotational movement of the magnetic portion. At least one of the sensors may extend across a side of the magnetic portion.

Alternatively, a set of group of four lifting magnets attached to, or separated from, a group of four sensors may be located in the region of the first side, or axis, and a similar set of lifting magnets and sensors are located in the region of the second, or opposite, side of the axis, which arrangement may be triplicated for 3-axes of geometrical symmetry.

The levitated magnetic portion may include discrete magnetic regions located adjacent to each of the sensors and the lifting magnets. At least one of the magnetic regions comprises a generally flat region, or a thin yoke comprises permanent magnets.

A second magnetic or sensing fields may be arranged to act on different opposed sides of the magnetic portion to those on which the first magnetic or sensing field acts on, the second magnetic field, when viewed from a particular direction, being arranged to be generated by a first magnetically operable means located on a third side of the arrangement,and second and third magnetically operable means located on the opposed fourth side of the arrangement, the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the magnetic portion.

A third magnetic or sensing fields may be arranged to act on different opposed sides of the magnetic portion to those on which the first and second magnetic or sensing fields act on, the third magnetic field, when viewed from a particular direction, being arranged to be generated by a first magnetically operable means located on a fifth side of the arrangement, and second and third magnetically operable means located on the opposed sixth side of the arrangement,the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the magnetic portion.

The levitated magnetic portion may exhibit crystallographic system of geometry and may be cubic and/or may have generally planar sides.

According to another aspect of the present invention a magnetically responsive or transmittible arrangement includes a levitatable movable fully or partially magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first sensing means being arranged to sense movement of opposed sides of the magnetic portion, that first sensing means, when viewed from one direction, being arranged to sense movement of a first side of the magnetic portion towards or away from a first sensor in a first direction and second and third spaced sensors being arranged to sense movement of a second side of the magnetic portion, opposed to the first side, towards or away from the second and third sensors in second and third directions respectively, the first direction being arranged to extend between the second and third directions.

According to another aspect of the present invention, a method of operating a magnetically responsive or transmittible arrangement including a levitated movable magnetic portion acted on by a first magnetic field including first, second and third magnetically operable means, comprises exerting forces on the movable magnetic portion with the force exerted on the magnetic portion by the first magnetically operable means acting on a first side of the magnetic portion in a direction extending between the directions in which the second and third magnetically operable means act on a second side of the magnetic portion opposed to the first side.

The method may comprise changing the translational force between the first and second sides being applied to the magnetic portion by altering the force exerted by the first magnetically operable means alone.

The method may comprise changing the rotational force being applied to the magnetic portion about an axis extending transverse to the extent between the first and second sides and transverse to the extent between the second and third magnetically operable means by altering the force exerted by one of the second or third magnetically operable means.

According to another aspect of the present invention a three dimensional active receiver or transmitter enables axes forces to be crystallographically oriented may lead to non-interaction of axes control system as well as the production of 3-axes control, 3-axes bi-directional translation and rotation forces, and providing mutually reversible couples to enable motions, of fully or partially magnetic material of levitated crystallographic object, about each of the control axes; wherein each axis comprising of three electronically controlled lifting electromagnets mounted such that two dynamic magnets are in close proximity to one face of the levitated object and the third is in close proximity to the axially opposite axis of the levitated object, and three transducers mounted such that opposite to the lifting magnets.Alternatively, each axis compri sing of four electronically controlled lifting electromagnets mounted such that four dynamic magnets,attached to or separated from four sensors, are in close proximity to one face of the levitated object and the similar set is in close proximity to the axially opposite axis of the levitated object.

The levitated object may be arranged to be stationary and the housing move freely in any direction or dimension with six degrees of freedom, and vice versa.

According to another aspect of the present invention a 3D transmitter includes a non stationary levitated object arranged, in use, to be located inside electromagnetic housing, which levitated object being arranged to move with 6-degrees of freedom, and translational and rotational motions of the levitated object being arranged to be driven by multi-phases fluctuating electronic signals. - Alternatively, a 3D receiver includes a stationary levitated object arranged, in use, to be located inside electromagnetic housing, which housing being arranged to move in an infinite directions, and translational and rotational motions of the levitated object being arranged to be driven by gravity or magnetic force or mechanical vibrations.

The movement of the levitated object is related to the housing movement to regain the datum position, this may be arranged to change the input electromagnetic fields. Alternatively or additionally a change in the electromagnetic field may be arranged to cause movement of the levitated object.

The arrangement may include an indicator, which indicator may be arranged to provide an indication of a change in the electromagnetic field. The indicator may comprise an electronic signal input means. The indicator may comprise an electronic control design means. The indicator may comprise a method of energising the levitated magnets.

For the purpose of calibration the indicator may need an engineered electronic, or jig, micrometer comprising a micrometer and movable anvil,to provide accurate easurements of small linear displacements of the levitated object from the stationary position of the housing. The arrangement may comprise magnets and transducers. The lifting magnets may consist of an iron yoke, magnetic cores, cone, and carrying coils of wire.

The magnets may be energised by the power electronics. The transducers may consist of an iron yoke, two small permanent magnets, and two hall-probes. The transducers may consist of other arrangement, which arrangement is sensitive to small changes in the magnetic flux. The position signal may be uncontaminated by noise and it may be,therefore, considered feasible to electronically pseudo differentiate this signal to achieve a suitable signal.

The arrangement may comprise modular construction of the electronics so that the circuit boards are common to each axis.

Alternatively, the modular construction of the electronics may comprise one circuitry so that the circuit boards are common to 3-axes control. The electronic circuitries may comprise digital controller. The electronic circuitries may comprise linear and/or non linear controller.

The reference position of the levitated object may be arranged to move in relation to the electromagnetic field and housing, in response to the multi-axes of mechanical vibrations or electronic signals incident upon the arrangement.

The electromagnetic field may be provided by a plurality of dynamic magnets and electrical coils each of a different orientation and along axes of crystallographic system of geometry.

Preferably, the levitated object may comprise a sample of non magnetic chassis unit with ferrous patches to minimise interaction between the axes of control. The magnetic patches may not have equal sizes, lengths or widths. The magnetic patches may be arranged parallel to the lifting magnets and/or the sensing transducers. The magnetic patches may have equal surface area to the lifting magnets or the sensing transducers.

The levitated object may experience partially magnetic material, said non magnetic material with patches composed of ferro-magnetic or para-magnetic material. The levitated object may experience dia-magnetic or non-magnetic core. The core may experience crystallographic system of geometry, which geometry may be arranged to be similar or identical to the geometry of the levitated object or the geometry of the electromagnetic housing. The housing may experience a non-magnetic protective guard along the border to protect the levitated object.

The levitated object may be arranged to experience both magneto-static and magneto-dynamic levitation, or sensing means.

The arrangement of an infinite force magnetics in each axis may provide both positive and negative translational and rotational forces for each of the 3-axes.

The arrangement of the levitated object may comprise of four electronically controlled lifting electromagnets mounted such that four dynamic magnets, attached to or separated from four sensors, are in close proximity to one face of the levitated object and the similar set is in close proximity to the axially opposite axis of the levitated object.

The arrangement of the levitated object housing may comprise of three position lifting magnets per axis. These may be mounted such that two magnets are in close proximity to one face or axis of the levitated object and the third is in close proximity to the axially opposite face or axis of the levitated ob ject. The arrangement of the levitated object housing may comprise of three position transducer per axis. These may be mounted such that opposite to the lifting magnets.

According to a further aspect of the present invention,a method of operating a 3D magnetically responsive or transmittible arrangement including a levitated movable magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first magnetic field being arranged to act on opposed sides of the magnetic portion, that first field, when viewed from one direction, being arranged to be generated by four magnetically operable means attached to, or separated from, four sensing means located on a first side or axis of the arrangement and the similar set of magnetically operable and sensing means located on an opposed second side of the arrangement, the force and sensing exerted on the magnetic portion by the first magnetically operable and sensing means being arranged to act in a direction extending parallel the directions in which the second magnetically operable and sensing means are arranged to exert a force and sensing on the magnetic portion, and this arrangement being made along one axis of the levitated object, to enable the electronics and arrangement to be triplicated for 3-axes of the crystallographic system of operable geometry and proportional to the geometry of the levitated magnetic portion.

According to a further aspect of this invention, a method of operating a three dimensional active receiver or transmittible arrangement enables axes forces to be crystallographically oriented leading to non interaction of axes control system as well as the production of axes bi-directional translation forces and providing mutually reversible couples to enable motions of partially magnetic material of levitated crystallographic object about each of the control axes; wherein each axis comprising of three electronically controlled lifting electromagnets mounted such that two dynamic magnets are in close proximity to one face of the levitated object and the third is in close proximity to the axially opposite axis of the levitated object, three transducers mounted such that opposite to the lifting magnets, for each axis.

The method may include the electromagnetic housing being stationary related to the levitated object, or vice versa, which may be arranged to move substantially in any direction.

According to a further aspect of the present invention a method of operating a 3D receiver or transmitter including a levitated object comprises locating the levitated object stationary inside the electromagnetic field housing, or vice versa, and allowing the levitated object to move in any direction and the movement of the levitated object inside the electromagnetic field is due to the incident signals.

The method may include the levitated object being arranged to be levitated, for example by magneto-dynamic field. Movement of the levitated object may be arranged to change the surrounded electromagnetic field.

Alternatively the method may provide that a change in the electromagnetic field is arranged to cause movement of the levitated object.

The method may comprise interpreting signals from an indicator means, which signals may be indicative of the input and the responsive or transmittible output signals. The method may comprise technique of obtaining the correct magnet currents from the transducer outputs. The method may comprise a technique of energising the levitational magnets. The method may comprise a modular construction of the electronics so that the circuit boards are common to each axis, or 3-axes control.

The method may comprise a technique for an electronic design.

For the purpose of calibration,the apparatus method may consist of a specially engineered electronic, or jig, micrometer comprising a micrometer and movable anvil to provide accurate measurement of small linear displacements, or flux change of the pole shoe, or levitated object, from the position transducer.

The signal output means may include means to filter the noise from the desired signals. The computational output means may include means to increase the signal to noise ratio. The computational output means may include means to regulate the balance between the feedback current and the electronic signals that induce the magnetic levitation.

The sample of levitated object may experience or exhibit ferromagnetic patches and a non-magnetic core. The levitated object, the levitated object's core, the surrounded airgap and/or magneto-dynamic housing may experience crystallographic system of geometry. The surrounded airgap may experience a nonmagnetic protective guard along the border to protect the levitated object inside.

The sample of levitated object may experience magneto-dynamic levitation in the field of the device. The signal input or output means may be capable of controlling the magneto-dynamic levitation. The dynamic magnets may be arranged along the axes of crystallographic system of geometry. The sample of levitated object may experience magneto-static levitation. The magnetostatic levitation or sensing means may be effected by an infinite axes of static and/or dynamic magnets. A cooling agent may be used to obtain a stable suspension inside magneto-static field.

The sample of levitated object may- experience both magnetostatic and magneto-dynamic levitation. The sample of levitated object may be levitated in space, against gravity field. The vessel of the apparatus may include a window through which the levitated object may be viewed.

The means to provide the electromagnetic field may comprise dynamic magnets and electrical coils. The dynamic magnets may be provided in numbers of even or odd multiples of 3,4, or greater than 9, and may be arranged along the axes of crystallographic system of geometry. The device may be operated by conventional methods, remote control or radio telemetry system.

According to a further aspect of the present invention a method of operating a magnetically responsive or transmittible arrangement including a movable magnetic portion comprises sensing movement of the magnetic portion with a first sensing means comprising a first sensor sensing movement of a first side of the magnetic portion towards or away from the first sensor in a first direction and second and third sensors sensing movement of a second side of the magnetic portion, opposed to the first side, towards or away from the second and third sensors in second and third directions respectively, the first direction extending between the second and third directions.

According to another aspect of the present invention an apparatus comprises means to provide an electromagnetic field, levitated object, dynamic magnets, and magnetic cores capable of being influenced by the electromagnetic field of the device, and an indicator means characterised in that, when the signals are incident upon the device, they cause the levitated object and/or vibrating plates or cones to move and vibrate in relation to the electromagnetic field of the device,which movements are arranged to provide an indication in the indicator means and transform the signals into the required output.

According to a further aspect of the present invention a method of transmitting audible stereo sound comprises providing electromagnetic fields of the device, a levitated object capable of being influenced by that field, magnetic core attached to, or part of, a dynamic magnet, vibrating cone or fibres, electronic circuitry, and monitoring movement of vibrations of said levitated object and the vibrating plate or fibres of the magnetodynamic field of the device and providing indications of that sound. The device may be contained in a preferred shape of an elastic vessel. The components of the device may have low sound absorption and/or reflection coefficients.

According to another aspect of the present invention a method of transmitting or receiving mechanical vibrations and gravity or magnetic forces of energy. The apparatus comprises providing electromagnetic units composed of a levitated object of fully or partially magnetic material, permanent magnets, yoke, coils, hall-probe and the computational and control circuitries.

According to yet a further aspect of the present invention there is provided apparatus substantially as herein described when used in a method substantially as herein described.

EXAMPLE Specific embodiments of the present invention will now be described by way of example only and with reference to the diagrammatic drawings in which Figure 1 shows a 3D illustration-of 3-axes cube levitational system, (10 is the partially magnetic levitated cube).

Figure 2 shows a 3D schematic view of an embodiment of an active stereo speaker apparatus such as may be used in transmi ssion of stereo sounds, (11 the sensor,12 the lifting magnet,13 the cone).

Figures 3 and 5 show a crystallographic symmetry of the levitated object 10, (20 and 41 are the magnetic patches adja cent to the sensors 11; 21 and 40 are the magnetic patches adjacent to the lifting magnets 12).

Figures 4 and 6 show the corresponding arrangements of the sensors 11 and lifting magnets 12 around the levitated object 10.

Figure 7 shows a 3D view of the sensor 11, (75 is the sensing yoke, 76 the permanent magnet, 77 the Hall-Probe).

Figure 8 shows a 3D schematic diagram of the lifting magnet 12 for transmittible apparatus, (60 is the lifting electromagnetic yoke, 61 and 62 are magnetic cores, 63-65 the electrical coils, 66 the airgap, 67 the dust-cap, 68 the supporting leg or frame, 69 the suspension or surround, and 70 the spider).

Figure 9 shows a 3D of force magnet yoke, as lifting magnet 12 for the responsive apparatus, (30 is the yoke, 31 the coil).

Figure 10 illustrating one axis of the cube system of figure 1.

Figure 11 shows the jig micrometer, (150 is the spring, and 151 the mechanical micrometer).

Figure 12 shows a linearised schematic diagram of the single magnet levitational control system, (I is the current, X the distance, g the gravity force,S Laplace,K the gain,T the time).

Figure 13 shows a block diagram of a single magnet levitation. Figure 14 shows a block diagram of 3-Magnets of a single axis translational and rotational control.

Figure 15 shows the schematic diagram of an electronic differentiator, (R is the resistor, C the capacitor).

Figure 16 shows a schematic diagram of an electronic circuitry for horizontal axis control.

Figure 17 shows a graph of voltage output versus airgap displacement of position.

Figure 18 shows the oscilloscope printout of velocity differential of displacement or position.

Figure 19 shows the 3D dipole path of the levitated object 10 at frequency excitation of 1,000 Hz.

Figure 20 shows the frequency response of the levitated object at the 1,000 Hz dipole excitation.

According to one embodiment, figure 1, the practical crystallographic geometry is the cube arrangement which enables 3-axes forces to be orthogonally oriented leading to non-interaction of 3-axes control system. As well as the production of 3-axes bi-directional translation forces it is necessary to provide 3, or 4,mutually orthogonal reversible couples to enable rotation of the levitated object 10 about each of the crystallographic axes. The symmetrical motion of the levitated object 10, enables the magnetic levitation system and associated electronics for one axis to be triplicated to form 3-axes levitation system,or infinite crystallographic axes of the levitation system.

This simplifies the production requirements of both the electromagnets and the control electronics, enabling modular construction techniques to be employed. The system uses a fully or partially magnetic cube 10 or other crystallographic geometry, which is made of a light non magnetic material, possibly Aluminium 10 with or without lightening holes and provided with magnetic patches 20/21 or 41/40. With a crystallographic symmetry of cubical approach, the provision of three magnets in each axis can provide positive and negative translational and rotational forces in each axis and given airgap between the levitated object and the surrounded electromagnetic and sensing fields, it is always possible to gain control of the cube whatever its position in the unenergised state.

The assembly of the non magnetic cube and the magnetic patches is sketched in figures 3-10. Each axis may have three electronically controlled lifting magnets 1-2, these may be mounted such that two dynamic magnets (A+B) are in close proximity to one face or axis of the cube and the third (C) is in close proximity to the axially opposite face or axis of the cube.

Also, each axis may have three transducers 11, these will be mounted such that opposite the above mentioned arrangement of the magnet, figures 1 and 3-4.

In another embodiment, each axis may have four electronically controlled lifting electromagnets 12 attached to, or separated from, a similar group of transducers 11, figures 5-6. These may be mounted such that four lifting magnets 12 attached to, or separated from, their transducers are arranged or spaced in close proximity to one face or axis of the cube and a similar group are in close proximity to the axially opposite face or axis of the cube.

These arrangements of the 3- or 4-lifting magnet systems are for each of the 3-axes (X,Y,Z) of the-crystallographic symmetry. The net Axial translation forces of the 3- and 4-lifting magnet systems are given by the following mathematical modelling; F(A) + F(B) - F(C) - F(g) 1 or F(AR+)+F(BR+)+F(AL+)+F(BL+) tF(AR-)+F(BR-)+F(AL-)+F(BL-) + F(g)] where F(A),F(B),F(C), or the equivalents are forces produced by the electromagnets A, B, and C respectively; F(g) is the axial component of gravity. L & R are for the left and right side, +/- are for the axes directions.

For non-rotational displacement of the levitated cube 10 in the axial direction of magnets A, and B or the equivalent F(A) = F(B) 2 or F(AL+)+F(AR+) = F(BL+)+F(BR+), and F(AL-)+F(AR-) = F(BL-)+F(BR-) which represents a balanced attractive force from each of the two magnet systems, figures 3-6 ; and F(A) + F(B) > F(C) + F(g) 3 or F(AR+)+F(BR+)+F(AL+)+F(BL+) > (F(AR-)+F(BR-)+F(AL-)+F(BL-) + F(g)) where F(C) of the 3-magnet system, or tF(AR-)+F(BR-)+F(AL-)+ F(BL-)] of the 4-magnet system will be sent to a small standby force to minimise dissipation and power consumption.The axial movement in the opposite direction requires; F(C) + F(g) > F(A) + F(B) 4 or [F(AR-)+F(BR-)+F(AL-)+F(BL-) + F(g)] > F(AR+)+F(BR+)+F(AL+)+F(BL+) where F(A) and F(B) or the equivalents will be at a small symmetrical standby value. The rotational forces are produced by a differential application of F(A) and F(B).For axial rotation in one direction; F(A) > F(B) 5 or F(AL+)+F(AR+) > F(BL+)+F(BR+), and F(AL-)+F(AR-) > F(BL-)+F(BR-) and to reverse rotation; F(B) > F(A) 6 or F(AL+)+F(AR+) < F(BL+)+F(BR+), and F(AL-)+F(AR-) < F(BL-)+F(BR-) To prevent translation; F(A) + F(B) = F(C) + F(g) 7 or F(AR+)+F(BR+)+F(AL+)+F(BL+) = [F(AR-)+F(BR-)+F(AL-)+F(BL-) + F(g)] The single axis magnetic levitation of any mass by a magnet system is governed by the following differential equation v = dx / dt; a = dv / dt 8 a =(Ki2 / ( ss X ) ) - g 9 Where x,v,a are the displacement, velocity, and acceleration of the levitated mass, the airgap that surrounds the levitated mass, g the acceleration due to gravity, and i the magnetising current to overcome acceleration.

K the proportionality constant.

Equation 9 is non linear and dynamically unstable. Before control can be applied, it is necessary to linearise the nonlinear equation about a nominal operating point. This may be performed using Newton Raphson Algorithm which linearises the non linear equation, and to prevent any signal distortion.

Applying this algorithm to the equations of motion of a single magnetic levitation system, the non linear equation 9 becomes; a = 2 g C (x/x) + (i/I) - (X/x ) ] 10 The linearised equation 10 clearly exhibits a positive feedback term in the acceleration equation due to displacement. If we assume the plane wave displacement of the levitated mass (pressure,rotation, dilatation, etc.) is (x = #), then we have the following rectangular co-ordination x,y,z of the levitated mass

where V=v is the velocity of the acoustic wave.In spherical co-ordinates where CO is the radius, o( the colatitude, and 4? the longitude, the spherical wave equation of the levitated mass becomes

In Laplace form the relationship (transfer function) between incremental current and displacement is given by 2 x/i = (2g/I) { L - (2g/xO) ) 13 Where x is for the levitated mass, relative to a datum airgap xO, i the incremental magnetising current to overcome (x), I the standing current to overcome gravity, and L Laplace operation.

The undamped natural frequency of the magnetically levitated mass is electronically governed by the forward path gain Kl.

The relationship is 2 W0 = 2 g K1 / I 14 The system damping is controlled electronically by the gain parameter Kz, with the following relationship K2 g = I D WO 15 0.5 D = K2 / [ g / 2 K1 I ] 16 Where D is the damping ratio, and W is the undamped natural frequency.

The significant difference between the spring mass system device and the magnetically levitated system is that the natural frequency can be made much higher in the magnetically levitated system. This because the system is active and (K) can be chosen electronically to provide the desired natural frequency. A higher natural frequency means that the system will respond to external accelerations of a higher frequency bandwidth.

To compare the present apparatus system with the conventional one of the spring suspension system, the spring mass device is a passive device which has the following equation of motion describing the displacement of the mass; mar + Dr vr + k r x r = ( Fr - m ar ) 17 and the undamped natural frequency is wo = kr / m 18 Where k is the spring constant, m the spring suspended mass, F the force due to gravity (mg).

x the relative displacement between the case and the mass, D the damping force per unit velocity, and The gravitational force produce a sag equivalent to (mg/k), which is equal to (g/w2). The spring mass system, passive device, typically has a natural frequency of the order of 1-10 Hz and this is fixed by the spring constant/mass ratio. Damping is provided by either a viscous dashpot or magnetic damping proportional to velocity.

With the 6-degrees of freedom of levitation system, it is necessary to provide at least two position sensors per axis, this enables the rotational motion to be detected. The rotation rates may be obtained by differential displacement pseudo differentiation. The translational acceleration may also be required and may be obtained by an additional sensor mounted on -- the pole-face of the lifting magnets -12, or by pseudo differen tiation of the translational velocity signal.

The control will be provided for each of the three axis tran slational and rotational modes, figure 12. The sensing will include displacement, and current in the force magnet coils.

he levitated cube 10 may be control to null or damp any tran slational or rotational motion. The control may be maintained when the unit is subjected to an acceleration of, for example, -/+ 10.0 (g) at 1.0 mm displacement. This magnetic levitational system may have a natural frequency of more than 100 Hz, at particular gain parameters, and can provide velocity outputs in excess of 1.OK Hz using suitable filtration to give a much enhanced flat frequency response, while the natural frequency for typical spring mass system is of the order of 1-10 Hz.

It may be necessary to provide at least 3-position magnets and 3-position transducers per axis, as shown in figures 4 and 10.

Alternatively, it may be necessary to provide four magnetically operable means 12 attached to, or separated from, four sensing 11 operable means located on a first side of the arrangement and a second similar set of lifting 12 and sensing 11 operable means located on an opposed second side of the arrangement, to exert lifting and sensing forces on the magnetic portion 10 along one axis, enable the system and electronics to be tripli cated for 3-axes and proportional to the geometry of the levitated magnetic portion, as in figures 5-6.

The lifting magnet 12 consists of an iron yoke 60 or 30, and carrying coils of wires 63-65 or 31, as in figures 8-9. The magnets 12 and the transducers 11 are energised by the power electronics, figures 12, 15, and 16.

The principle of operation is that the flux driven by the permanent magnet around the iron yoke and the strip of magnetic material on the cube 10 varies in sympathy with the length of the air gap. The relationship between flux and air gap length is approximately inverse.

The transducer 11 consists of an iron yoke 75, two small permanent magnets 76, and two hall-probes 77, figure 7. The alternative transducers or design may be placed. The Neodymium Iron Boron permanent magnets 76 may be mounted on the iron yokes 75 in such a fashion as to produce a "horse house" magnet with North and South poles. The hall-probes are positioned so that the majority of flux,produced by the perma nent magnets, passed through the most sensitive region of the hall-probe. It may be arranged so that the hall-probe signals could be added. A UGN3503U Hall-Probe 77, or the alternative components, may be used based on its high sensitivity, its compact size, and the very low noise output.

It may be necessary to reduce the length of the permanent magnet 76, to reduce the magnetic forces from the permanent magnet transducer. Therefore, this will reduces the magnetomotive force of the magnet and the flux density in the airgap.

A reduction in the flux density enabled a reduction in the cross section area of the yoke. The sensitivity of the tran will not free to rotate about its levitation point. A block diagram showing a single magnet levitation of the system is given in figure 13. The system may be excited using sinewaves, causing the levitated cube 10 to execute simple harmonic motion SHM in vertical plane.

It may be necessary to design a method of energising the magnets 12 in a fashion to provide translational and rotational control. This is shown in figure 14, wherein the positions of the three magnets A, B, and C are shown in figure 10. It may be necessary to energise the magnets with only positive currents.

The electronic circuit may be designed such that for translational motion, the two magnets on one side, A and B or the equivalent,are energised to produce a translational force, whilst magnet C or the equivalent receives no input. Therefore to reverse the force, magnet C or the equivalent is energised, whilst magnets A and B or the equivalent remain unenergised.

This may be accomplished by using non-linear function using electronic diodes. A similar operation may be used on magnets A and B,or the equivalent,to control the rotation forces. Magnet A, or equivalent, may be energised to give positive rotation, whilst magnet B,or equivalent,receive no energisation from the rotation channel. For the negative rotation the process is reversed. Magnet B may be energised, whilst magnet A receives no input from the rotation channel.

A circuit diagram of the structure of the translational and rotational control system may be designed according to the arrangement of the lifting magnets 12 and transducers 11. The error signals from the translational transducer may be fed to a proportional plus integral controller, the output of which may sum with a velocity damping signal to provide a current demand for the appropriate magnet(s). Preferably, a linear and/or nonlinear digital controller may be used. The rotational position signals feed a similarly constructed proportional plus integral controller, again summing with the rotational velocity damping signal and subsequent magnet energisation.

All of the signal computation which may be used to control the system may be performed using operational amplifiers,resistors, diodes, and capacitors, figures 15-16. Because of the great number of operational amplifiers needed, it may be decided to exploit the use of Quad op-amplifier, four op-amplifiers on one silicon chip, or the alternative components, may be used, and the RC4136N Quad Op-Amplifier may be chosen. The L165 power operational amplifiers may be used to energise each of the force magnets, wherein the heatsinks used are of universal design and may be matched to the requirements of the power amplifiers. Ruggedising the electronics for severe in-service conditions will be possible using standard techniques.

The lifting magnet 12 may have a cone 13 attached to dynamic magnet 60 as shown in figures 2 and 8. The horizontal distance between far ends of the cone frame 68 can range from a few inches to 15 inches. The larger the size, the more volume the apparatus can produce. The two sided dynamic electromagnets 60 or 62, the levitated object 10, and the voice coil 65 make up the driver of the apparatus. The voice coil 65 consists of many turns of fine wire wound on the bobbin coil 65. The fluctuated multi-phases or axes of input electrical signals from an amplifier are applied to the voice coils 65 and/or 64.

The magnet 62 consists of a bobbin and magnetic core. The bobbin 62 may consist of two types of coils. The first is similar to the coil 65, which may cause the levitated magnetic material 10 to vibrate. The second coil provides the necessary current that creates the magnetic field inside the core 62, which is automatically controlled by a circuit control to maintain the electromagnetic levitation of the levitated object 10. The physical dimensions of the levitated object, airgap, dynamic magnets and cones are proportional to the output power and the dynamic electromagnetic forces. A varying electromagnetic field is produced around the voice coils 65 and 64, and activated by the fluctuating multi-axes, or phases, of an input signals.

This field aids or opposes the dynamic electromagnetic field produced by the dynamic magnets 60,61, or 62 which are fixed in their frame position 68. Therefore, the voice coil 65 and the levitated object 10, being inter-related, move as the magnetic fields interact. As the multi-phases,or axes, of the electronic signals are continuously fed to the apparatus, the varying electromagnetic field causes the voice coil 65 and the levitated object 10 to move back and forth over the magnetic core 61, inside the airgap 66 respectively. The voice coil 65 is wound around a small paper called bobbin 65, which is attached to the cone 13. The vibrating levitated object 10 uses the air as a coupling medium.

When the voice coil 65 and the levitated object 10 move because of the fluctuating input of electronic audio signals applied to them, the bobbin 65 moves the cone 13 and causes it to vibrate.

The dust cap 67 placed over the bobbin 65 forms the inside centre of the cone and keeps dust and debris from entering the small air gap 66 between the voice coil 65 and the central magnetic core 61. The cone 13 has flexible suspension elements 69 and 70, and the flexible spider 70 attaches the voice coil 65, bobbin, and inner portion of the cone 13. At the other end of the cone 13 is of flexible rubber, foam, or paper element called suspension or surround 69, as shown in figure 8.

A control unit is connected to the terminals of each of the electrical coils. A powered current source (internal or external) maintains the magneto-dynamic levitation of the levitated object 10 in conjunction with a feedback circuit.

The feedback control circuit regulates the balance between the feedback current source and the multi-phases of fluctuating input electrical signals or mechanical vibrations,and separate the feedback signals and other sources of noise (thermal noise, noise due to coil resistance, and Brownian particle motion in the gas within the vessel, etc.) from the induced signals. The feedback circuit control also increases the induced signal to noise ratio. The feedback control circuit regulates the balance between the feedback current and the induced signals, and separates,or filters, the induced signals from other sources of non desired noises.The output induced signals are corresponding to the fluctuating input electronic signals of multiphases and directions, and these induced signals are translated or induced by the translational and rotational motions of the levitated object 10 and the vibrations of the cone 13. The fluctuating input electronic signals may be transmitted through a radio telemetry system to be read by the control circuit.

It is desirable that the levitated object should be small and, light. This will minimise the power needed for the instrument and increase the frequency response.

In such an active apparatus, the control voltage is necessary to maintain the housing of the levitated object stationary when the levitated object is shaken by the incident fluctuating audio signal, or vice versa. In this case, the X,Y, and Z translational and rotational vibrations could be produced by one system and one levitated object. The resonant frequency of the levitated object along any axis should be controllable by the gain of the feedback system within the expected stability limits. It is also expected that the "g" forces which the levitated object can withstand before 'bottoming' are also dependent on the gain of the circuitry. Therefore, it would not be possible to achieve any resonant frequency computational with any degree of apparatus sensitivity.

The levitated object may, in some cases, work as a set of three orthogonal dipole. This is because of the movement of the rear surface is causing rarefactions while the front surface is causing compressions, and vice versa. This may be true also for the two other orthogonal axes. Furthermore, due to the small size of the levitated object relative to a wavelength, separate signals fed into all three axes may simply merge to produce one source having a dipole characteristics. The direction of the computational sources dipole lobes depends on the relative phases of the three incident signals, as shown in figure 19, where the levitated object is vibrated at frequency of 1.0 KHz.If we want to remove this inherent "dipoleness" and so increase the low frequency transmission or reception efficiency, it may be necessary to place a baffle large compared with a wavelength midway along each face of the levitated object and totally encircling it. Alternatively, it may be necessary to increase the size of the levitated object to become larger than a wavelength at the lowest frequency of interest. There may still be a dipole characteristic, but we may be well up the 6db per Octave falling response curve characteristic of all simple dipoles, as shown in figure 20.

In the present apparatus technology, the size and mass of the levitated object, the airgap surrounds the levitated object, and the incident signals upon the apparatus determine the sensitivity. Increasing the airgap surrounds the levitated object may decrease the sensitivity and vice versa, while increasing the other two parameters may increase the sensitivity. There is also a combination of mass, force, and resonant frequency which may result in a desired low frequency turn over and roll off characteristic. With the present method, the moving mass is relatively small, the airgap surrounds the levitated object is relatively small, while the force depends on the incident signals. The sensitivity will therefore be correspondingly very high, and the power consumption may be made much lower than 3.0 Watts.

However, it is recommended to construct and maintain a digital controller, which controller may comprise linear and/or nonlinear control systems. This will guarantee a fully computerised system for processing and interpretations of the induced signals.

Claims

1. A magnetically responsive arrangement including a levi tatable movable fully or partially magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first magnetic field being arranged to act on opposed sides of the magnetic portion, that first field, when viewed from one direction, being arranged to be generated by a first magneti cally operable means located on a first side of the arrangement and second and third magnetically operable means located on an opposed second side of the arrangement,the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the'magnetic portion.

2. An arrangement as claimed in Claim 1 in which the first magnetically operable means is arranged to act generally in the region of the centre of the first side, when viewed from the one direction.

3. An arrangement as claimed in Claim 1 or 2 in which the second and third magnetically operable means are spaced from each other.

4. An arrangement as claimed in any preceding claim in which the second and third magnetically operable means are arranged to act on opposed sides of the centre of the second side.

5. An arrangement as claimed in any preceding claim in which the first, second and third magnetically, operable means are arranged to be capable of causing movement of the magnetic portion in a transverse direction extending between the first and second sides.

6. An arrangement as claimed in any preceding claim in which the first, second and third magnetically operable means are capable of causing turning movement of the magnetic means about an axis transverse to the extent between the second and third magnetically operable means.

7. An arrangement as claimed in Claim 5 or 6 in which operation of one magnetically operable means is capable of causing the relative translational or turning movement of the magnetic portion.

8. An arrangement as claimed in any preceding claim in which at least one of the magnetically operable means extends across a side of the magnetic portion.

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9. An arrangement as claimed in any- preceding claim in which the magnetic portion includes discrete magnetic regions located adjacent to each of the magnetically operable means.

10. An arrangement as claimed in Claim 9 in which at least one of the magnetic regions comprises a generally flat region.

11. An arrangement as claimed in any preceding claim including sensing means arranged to monitor the location or movement of the magnetic portion, the sensing means comprising a first sensor arrangement being located in the region of opposed sides of the magnetic portion and including a first sensor located in the region of one of the first or second sides of the arrangement and second and third sensors located in the region of the other of the first or second sides of the arrangement, the first sensor being located at an intermediate region along its associated side, when viewed from one direction and the second and third sensors being located at different regions along their associated side.

12. An arrangement as claimed in Claim 11 in which the first sensor is located generally in the region of the centre of its associated side.

13. An arrangement as claimed in Claim 11 or 12 in which the second and third sensors are spaced from each other.

14. An arrangement as claimed in any of Claims 11 to 13 in which the first sensor is located in the region of the second side and the second and third sensors are located in the region of the first side.

15. An arrangement as claimed in any of Claims 11 to 14 in which the second and third sensors are located in the region of opposed sides of the sensor or their associated side.

16. An arrangement as claimed in any of Claims 11 to 15 in which the first, second and third sensors are capable of sensing turning movement of the magnetic portion about an axis transverse to the extent between the first and second sides and transverse to the extent between the spaced second and third sensors.

17. An arrangement as claimed in any of Claims 11 to 16 in which the first, second and third sensors are capable of sensing turning movement of the magnetic portion about an axis transverse to the extent between the first and second sides and transverse to the extent between the spaced second and third sensors.

18. An arrangement as claimed in Claim 16 or Claim 17 when dependent upon Claim 16 in which the first sensor alone is capable of sensing movement of the magnetic portion in the transverse direction.

19. An arrangement as claimed in Claim 17, or Claim 18 when dependent upon Claim 17 in which the second and third sensors alone are capable of sensing turning movement of the magnetic portion.

20. An arrangement as claimed in any of Claims 11 to 19 in which at least one of the sensors extends across a side of the magnetic portion.

21. An arrangement as claimed in any of Claims 11 to 20 in which the magnetic portion includes discrete magnetic regions located adjacent to each of the sensors.

22. An arrangement as claimed in Claim 21 in which at least one of the magnetic regions comprises a generally flat region.

23. An arrangement as claimed in any preceding claim including a second magnetic field arranged to act on different opposed sides of the magnetic portion to those on which the first magnetic portion acts on,the second magnetic field, when viewed from a particular direction, being arranged to be generated by a first magnetically operable means located on a third side of the arrangement, and second and third magnetically operable means located on the opposed fourth side of the arrangement, the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the magnetic portion.

24. An arrangement as claimed in Claim 23 including a third magnetic field arranged to act on different opposed sides of the magnetic portion to those on which the first and second magnetic fields act on, the third magnetic field, when viewed from a particular direction, being arranged to be generated by a first magnetically operable means located on a fifth side of the arrangement, and second and third magnetically operable means located on the opposed sixth side of the arrangement, the force exerted on the magnetic portion by the first magnetically operable means being arranged to act in a direction extending between the directions in which the second and third magnetically operable means are arranged to exert a force on the magnetic portion.

25. An arrangement as claimed in any preceding claim including an infinite number of operable magnetic fields arranged to act on different opposed sides or faces of crystallographic axis of fully or partially levitated magnetic portion and identical or similar to those on which the first and second and third magnetic fields act on, arranged along crystallographic axes of geometrical symmetry.

26. An arrangement as claimed in any preceding claim including an infinite number of operable sensing means of fields arranged to act on different opposed sides or faces of crystallographic axis of fully or partially levitated magnetic portion and identical or similar to those on which the first and second and third sensing means or fields act on, arranged along crystallographic axes of geometrically symmetry.

27. An arrangement as claimed in any preceding claim in which the fully or partially magnetic portion exhibits crystallographic system geometry.

28. An arrangement as claimed in any preceding claim in which the levitated magnetic portion is generally cubic.

29. An arrangement as claimed in any preceding claim in which the sides of the magnetic portion are generally planar.

30. A 3-dimensional operable arrangement enables axes forces to be crystallographically oriented leading to non-interaction of axes control system as well as the production of axes bidirectional translation forces and providing mutually reversible couples to enable motions of the levitated crystallographic object about each of the control axes; each axis comprising of three electronically controlled -lifting electromagnets mounted such that two dynamic magnets are in close proximity to one face of the levitated object and the third is in close proximity to the axially opposite axis of the levitated object, and three transducers mounted such that opposite to the lifting magnets; including means for crystallographic control, means for applying levitational forces, and means for responsive characteristics of translational and rotational motions; and operated when energised by gravity or magnetic forces or mechanical vibrations, or fluctuated audio electronic signals.

31. An arrangement as claimed in any preceding claim wherein the levitated object comprising a non-magnetic chassis unit with ferrous patches to minimise interaction between the axes of the control.

32. An arrangement as claimed in any preceding claim wherein the levitated object comprises a non-magnetic chassis unit of crystallographic or cubical form with ferrous patches to minimise interaction between the axes of the control.

33. An arrangement as claimed in any preceding claim wherein the stationary position of the levitated object may be arranged to move in relation to the electromagnetic field and housing in response to the multi-axes mechanical vibrations incident upon the arrangement, or vice versa.

34. An arrangement as claimed in any preceding claim in which the levitated object is arranged to experience levitated motions and in any direction.

35. An arrangement as claimed in any preceding claim including an indicator, which indicator is arranged to provide an indication of changes in the airgap of levitated motions, or responsive signals.

36. An arrangement as claimed in Claim 35 wherein the indicator comprises levitation signals input means and responsive signals output means.

37. An arrangement as claimed in Claims 36 wherein the signal output means includes means to increase the induced signal to noise ratio, filter unwanted signals, and separate any feedback signal from the induced signals; which signals may comprise electronically pseudo differentiation.

38. An arrangement as claimed in any of Claims 34 to 37 wherein the indicator means comprises a method of energising the magnets.

39. An arrangement as claimed in any of Claims 34 to 38 wherein the indicator means comprises a non-linear/linear of analog and/or digital electronic control design means, and/or a modular construction of the electronics common to each axis.

40. An arrangement as claimed in any of Claims 34 to 39 wherein for calibration purposes the indicator means provide an engineered electronic, or jig micrometer which comprises a micrometer and a movable anvil to provide accurate measurements of linear displacements of the housing from the levitated object.

41. An arrangement as claimed in any preceding claim wherein the arrangement of three or an infinite number of forces magnetics in each axis may provide both positive and negative translational and rotational forces.

42. An arrangement as claimed in any preceding claim wherein the arrangement of the levitated object housing may comprise of three or an infinite position lifting magnets per axis which consist of iron yoke and carrying coils of wire.

43. An arrangement as claimed in any preceding claim wherein the arrangement of the levitated object housing comprise of three or an infinite position transducers per axis which consist of iron yoke, small permanent magnets, and hall probes.

44. An arrangement as claimed in any preceding claim wherein the input or responsive electromagnetic field is arranged to effect the motions of said levitated object.

45. An arrangement as claimed in any preceding claim in which the levitated object is arranged to experience levitated translational or rotational motions, with six degrees of freedom.

46. An arrangement as claimed in any preceding claim wherein the airgap changes or levitation housing is controlled by dynamic magnets which are arranged along axes of crystallographic system of geometry and proportional to the dimensions of said levitated object.

47. An arrangement as claimed in any preceding claim wherein the dynamic magnets or transducers are provided in numbers 3, 4, or even or odd multiples thereof and arranged along the axes of crystallographic system of geometry.

48. A magnetically operable arrangement including a levitatable movable fully or partially magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first sensing means being arranged to sense movement of opposed sides of the magnetic portion, that first sensing means, when viewed from one direction, being arranged to sense movement of a first side of the magnetic portion towards or away from a first sensor in a first direction and second and third spaced sensors being arranged to sense movement of a second side, opposed to the first side, of the magnetic portion, towards or away from the second and third sensors in second and third directions respectively, the first direction being arranged to extend between the second and third directions.

49. An arrangement as claimed in any preceding claims, in which the magnetic portion,when levitated, is able to move a distance grater than its dimension in any direction with six degrees of freedom.

50. A magnetically responsive or transmittible arrangement including a levitatable movable fully or partially magnetic portion arranged, in use, to be acted on by a magnetic field, the magnetic field and movement of the magnetic portion being inter-related, a first magnetic and sensing fields being arranged to act on opposed sides of the magnetic portion, that first field, when viewed from one direction, being arranged to be generated by four magnetically operable means attached to, or separated from, four sensing operable means located on a first side of the arrangement and second group of four magnetically operable means attached to, or separated from, four sensing operable means located on an opposed second side of the arrangement, the lifting and sensing forces exerted on the magnetic portion by the first magnetically operable and sensing means being arranged to act in a direction extending parallel to the directions in which the second magnetically operable and sensing means are arranged to exert lifting and sensing forces on the magnetic portion along one axis, enabling the electronics and this system of the lifting and sensing operable means to be triplicated for 3-axes of the crystallographic system of operable geometry and proportional to the geometry of the levitated magnetic portion.

51. A magnetically responsive or transmittible arrangement substantially as herein described, with reference to and as shown in the attached representations.

52. A method of operating a magnetically responsive or transmittible arrangement including a movable magnetic portion acted on by a first magnetic field including first, second and third magnetically operable means, the method comprising exerting forces on the movable magnetic portion with the force exerted on the magnetic portion by the first magnetically operable means acting on a first side of the magnetic portion in a direction extending between the directions in which the second and third magnetically operable means act on a second side of the magnetic portion opposed to the first side.

53. A method as claimed in Claim 52 comprising changing the translational force between the first and second sides being applied to the magnetic portion by altering the force exerted by the first magnetically operable means alone.

54. A method as claimed in Claim 52 or 53 comprising changing the turning force being applied to the magnetic portion about an axis extending transverse to the extent between the first and second sides and transverse to the extent between the second and third magnetically operable means by altering the force exerted by one of the second or third magnetically operable means.

55. A method of operating a 3D operable arrangement enables axes forces to be crystallographically oriented leading to noninteraction of axes control system as well as the production of axes bi-directional translation forces and providing mutually reversible couples to enable motions of the levitated crystal lographic object about each of the control axes; each axis comprising of three electronically controlled lifting electromagnets mounted such that two dynamic magnets are in close proximity to one face of the levitated object and the third is in close proximity to the axially opposite axis of the levitated object, and three transducers mounted such that opposite to the lifting magnets; including means for crystallographic control, means for applying levitational forces, and means for responsive characteristics of translational and rotational motions; and operated when energised by the incident energy field.

56. A method as claimed in any of Claims 52 to 55 in which the levitated object comprising a non-magnetic chassis unit with ferrous patches to minimise interaction between the axes of the control.

57. A method as claimed in any of Claims 52 to 56 in which the infinite translational and rotational motion of said levitated object changes the surrounding electromagnetic forces and/or vice versa.

58. A method as claimed in any of Claims 52 to 57 comprising interpreting input levitational signals and output responsive signals from an indicator means.

59. A method as claimed in any of Claims 52 to 58 in which three, four, or infinite force magnetics in each axis are to provide both positive and negative translational and rotational forces for the axis.

60. A method as claimed in any of Claims 52 to 59 in which the method comprises technique of obtaining correct magnet currents from the transducers output.

61. A method as claimed in any of Claims 52 to 60 in which the method comprises technique of energising the levitational magnets.

62. A method as claimed in any of Claims 52 to 61 in which the method may comprise a modular construction of the electronics so that the circuit boards are common to each axis.

63. A method as claimed in any of Claims 52 to 62 in which the method may comprise a technique for an electronic design.

64. A method as claimed in any of Claims 52 to 63 in which for calibration purposes the method may provide engineered electronic, or jig micrometer which comprises a micrometer and a movable anvil to provide accurate measurements of linear displacements of the housing from the levitated object.

65. A method of operating a magnetically responsive or transmittible arrangement including a movable magnetic portion acted on by a first magnetic and sensing fields including four magnetically operable means attached to, or separated from, four sensing means, the method comprising exerting lifting and sensing forces on the movable magnetic portion with the lifting and sensing forces exerted on the magnetic portion by the first magnetically operable and sensing means acting on a first side of the magnetic portion in a direction extending parallel to the directions in which the similar set of lifting and sensing operable means act on a second side of the magnetic portion opposed to the first side and a along one axis of symmetry, to enable the electronics and this system of the lifting and sensing operable means to be triplicated for 3-axes of the crystallographic system of operable geometry and proportional to the geometry of the levitated magnetic portion.

66. A method as claimed in any preceding claim in which regiddising the electronics for severe in-service conditions comprises using standard techniques.

67. A method of operating an electromagnetic arrangement substantially as herein described with reference to, and as shown in the accompanying representations.

68. A method of operating a magnetically responsive or transmittible arrangement including a movable magnetic portion comprising sensing movement of the magnetic portion with a first sensing means comprising a first sensor sensing movement of a first side of the magnetic portion towards or away from the first sensor in a first direction and second and third sensors sensing movement of a second side of the magnetic portion, opposed to the first side, towards or away from the second and third sensors in second and third directions respectively, the first direction extending between the second and third directions, and for 3-axes of crystallographic symmetry.

69. An electromagnetically operable arrangement including a movable magnetic portion arranged, in use, to be levitated by an electromagnetic field, the magnetic portion, when levitated, being capable of moving in three mutually perpendicular directions characterised in that the magnetic portion experiences spherical or crystallographic system of geometry.

70. An arrangement as claimed in any preceding claim, when the magnetic portion is levitated, it is able to move a substantial amount in any direction.

71. An arrangement as claimed in any preceding claim in which the magnetic portion,when levitated, is able to move a distance greater than its dimension in any direction.

72. An arrangement as claimed in any preceding claim in which a robotic configuration provides an apparatus which comprises of elements capable of sensing and controlling three dimensional movements of components connected to the apparatus, aimed as a device for holding together more than one part such that one part can swing relative to the other.

73. A method as claimed in any of Claims 52 to 72 when using an arrangement as claimed in any of Claims 1 to 51.