System comprising magnetically actuated motion control device

A system that includes a magnetically actuated motion control device comprising a housing defining a cavity and including a slot therethrough. A movable member is located within the cavity and is movable relative to the housing. A magnetic field generator located on either the housing or the movable member causes the housing to press against the movable member to develop a friction force.

FIELD OF THE INVENTION

The present invention relates to magnetically actuated motion control devices. In particular the present invention relates to magnetically actuated motion control devices that vary contact pressure between a first member and a second member in accordance with a generated magnetic field.

BACKGROUND AND RELATED ART

Magnetically actuated motion control devices such as magnetically controlled dampers or struts provide motion control, e.g., damping that is controlled by the magnitude of an applied magnetic field. Much of the work in the area of magnetically controlled dampers has focused on either electrorheological (ER) or magnetorheological (MR) dampers. The principle underlying both of these types of damping devices is that particular fluids change viscosity in proportion to an applied electric or magnetic field. Thus, the damping force achievable with the fluid can be controlled by controlling the applied field. Examples of ER and MR dampers are discussed in U.S. Pat. Nos. 5,018,606 and 5,384,330, respectively.

MR fluids have high yield strengths and viscosities, and therefore are capable of generating greater damping forces than ER fluids. In addition, MR fluids are activated by easily produced magnetic fields with simple low voltage electromagnetic coils. As a result, dampers employing MR fluids have become preferred over ER dampers.

Because ER and MR fluid dampers still involve fluid damping, the dampers must be manufactured with precise valving and seals. In particular, such dampers typically require a dynamic seal and a compliant containment member which are not particularly easy to manufacture and assemble. Further, the fluid type dampers can have significant “off-state” forces which can further complicate manufacture and assembly. Off-state forces refer to those forces at work in the damper when the damper is not energized.

The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.

SUMMARY OF THE DISCLOSURE

According to one aspect of the invention, a magnetically actuated motion control device is provided. The magnetically actuated motion control device includes a housing, and movable member and a magnetic field generator located on either the housing or the movable member. The housing defines a cavity in which the movable member is located and includes at least one slot. A magnetic field applied by the field generator causes the housing to press against the movable member and thereby provide friction damping.

The invention includes a magnetically actuated motion control device. The magnetically actuated motion control device is preferably comprised of a first housing member defining a cavity with the first housing member including a movable flexible finger. The magnetically actuated motion control device is preferably comprised of a second member positioned within the first housing member cavity with the first housing member movable relative to the second member with a magnetic field generator located on the second member. The magnetic field generator causes the movable flexible finger to press against the second member to produce frictional damping. In a preferred embodiment the second member is a stator having a center axis with the stator and the first housing being relatively rotatable around the central axis. Preferably the housing encircles the second member with the housing relatively rotatable around the second member.

The invention includes a magnetically actuated motion control device. The magnetically actuated motion control device is preferably comprised of a first housing member defining a cavity with the first housing member including a movable flexible finger. The magnetically actuated motion control device is preferably comprised of a second member positioned within the first housing member cavity. The second member is movable relative to the first member with a magnetic field generator located on the second member. The magnetic field generator causes the movable flexible finger to press against the second member to produce frictional damping. In a preferred embodiment the second member is a stator having a center axis with the stator and the first housing being relatively rotatable around the central axis. Preferably the housing encircles the second member with the second member relatively rotatable within the stationary housing. Preferably the first housing member and its movable flexible finger are rotationally stationary with the second inner member stator rotating within the first housing member and its movable flexible finger.

The invention includes a magnetically actuated motion control device comprised of a first housing member including a cavity formed therein and including a movable finger; and a second member disposed in the cavity; and at least one magnetic field generator mounted to cause the movable finger to be displaced toward the second member and thereby squeeze the second member. In a preferred embodiment the first housing member has an outer perimeter and includes a shaft, with the cavity for receiving the second member between the outer perimeter and the shaft.

The invention includes a method of controlling relative motion between a housing and a second member. The housing has a finger, with the housing and finger movable relative to the second member, and the housing defining a cavity in which the second member is located. The invention includes generating a magnetic field and pressing the finger against the second member in accordance with the generated magnetic field.

The invention includes a method of controlling relative motion between a housing and a rotating second member. The housing has a finger, with the housing and finger rotationally stationary. Preferably the second member is rotatably movable relative to the housing and finger, with the housing defining a cavity in which the second member is located. The invention includes generating a magnetic field and pressing the finger against the rotating second member in accordance with the generated magnetic field.

The invention includes a system with a magnetically actuated motion control device. The motion control device of the system has a finger that frictionally engages a circular stator to control a rotational motion of the system. Preferably the magnetically actuated motion control device is coupled to a shaft with a wheel, with the circular stator or the housing being rotatable relative to the shaft. In a preferred embodiment the wheel and is comprised of a control knob. Preferably the system includes a rotational sensor that tracks rotation and a magnetic field generated by the stator moves the finger to make a rotational end stop.

The invention includes a vehicle with a body and a door. The door is attached by a hinge to the body frame. The invention includes a magnetically actuated motion control device housing mounted between the door and the body to magnetically control a movement of the door relative to the body. A second member stator is received in a cavity inside the housing. A rotary position sensor is mounted with the housing to sense rotational movement of the device and the hinge. The second member stator has a center axis, with the stator and the housing being relatively rotatable around the central axis. Preferably the housing includes a shaft oriented with the central axis, with the shaft directly coupled to a rotating shaft of the hinge. In a preferred alternative the housing includes a shaft oriented with the central axis, with the shaft indirectly coupled to a rotating shaft of the hinge. In a preferred embodiment the housing and its movable finger are rotationally stationary with the second member stator rotationally received within the housing cavity such that the second member inner stator rotates relative to the stationary housing with the movable finger magnetically actuated into contact with the rotating second member inner stator to control rotation of the second member inner stator and the motion of the door relative to the vehicle body.

The invention includes a body frame and a door with the door being attached by a hinge to the body frame and a magnetically actuated motion control device with a first housing member defining a cavity. The first housing member includes a movable finger and a second member positioned within said first housing member cavity, with the second member movable relative to the first housing member. The second member includes a magnetic field generator with the magnetic field generator causing the movable finger to press against the second member to produce frictional damping with the magnetically actuated motion control device mounted to control a positioning of the door relative to the body frame. In a preferred embodiment the housing and its movable finger are rotationally stationary with the second member stator rotationally received within the housing cavity such that the second member inner stator rotates relative to the stationary housing with the motion on the door relative to the body frame at the hinge, with the movable finger magnetically actuated into contact with the rotating second member inner stator to control rotation of the second member inner stator and the motion of the door relative to the vehicle body frame.

According to another aspect of the invention, a sensor for sensing the position of a movable member relative to a housing of a magnetically controlled damper is provided. The sensor includes a first member secured to the housing, a second member, such as a slide, that is coupled to the movable member so that the relative position of the first member and the second member relates the position of the movable member within the housing. According to an exemplary embodiment, the movable member can include a depression for receiving an extension on the second member of the sensor. The extension of the second member fits through a slot in the housing and into the depression to couple the second member of the sensor to the movable member. In another embodiment, the second portion of the sensor can be configured so as to be in rolling contact with the movable member. In this embodiment, relative rotation between the first member and the second member indicates relative motion between the movable member and the housing.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

For a better understanding of the invention, the following detailed description refers to the accompanying drawings, wherein exemplary embodiments of the present invention are illustrated and described.

The present invention relates to a magnetically actuated alternative to traditional MR fluid motion control devices. A magnetically actuated motion control device according to the present invention can be embodied as linear or rotary dampers, brakes, lockable struts or position holding devices. The invention contains no MR fluid, yet provides a variable level of coulombic or friction damping that is controlled by the magnitude of the applied magnetic field.

In contrast to MR or ER fluid devices, a magnetically actuated motion control device according to the present invention is simple to manufacture and relatively low cost. A magnetically actuated motion control device according to the present invention also allows for very loose mechanical tolerances and fit between components. In addition, a magnetically actuated motion control device according to the present invention does not require a dynamic seal or a compliant containment member as does a fluid type damper, and is therefore relatively easy to manufacture and assemble. Further, a magnetically actuated motion control device according to the present invention has particularly low off-state forces which provide for a wide dynamic range between the off-state and a maximum damping force.

An example of a magnetically actuated motion control device according to the present invention includes a magnetically permeable tubular housing that moves relative to an electromagnetic piston and includes one or more coils, an associated magnetically permeable core or core pieces and associated pole regions. Although the housing in this example is tubular, a housing can be of any suitable cross section, including, but not limited to a rectangular cross section. The pole regions are located near an interface between the piston and the housing and carry magnetic flux in a generally radial direction with respect to a longitudinal axis running along the housing. The housing includes at least one slot but typically includes an array of slots. The housing slots allow the housing to flex and constrict radially when a magnetic field is applied by directing current through the coils. In so doing, the inner surface of the housing squeezes against the outer surface of the piston with a normal force that is approximately proportional to the magnitude of the applied magnetic field. Thus, the housing acts like a magnetically actuated collet that squeezes the piston to resist relative movement between the housing and the piston. Generally, the magnitude of the applied magnetic field is proportional to the electric current supplied to the coil. The damping force thus depends on the coefficient of friction between the inner surface of the housing and the outer surface of the piston and the normal force between these surfaces, which is dependent on the magnetic field produced by running current through the coils.

The invention allows for the accommodation of very loose mechanical tolerances or fit between the housing and the piston. Because the present invention does not require a dynamic seal or compliant containment member, it offers particularly low off-state forces and is simple to manufacture and assemble.

The present invention is particularly suitable for making low-cost, high-volume linear dampers for use in household appliances such as washing machines. Other applications for magnetically actuated motion control devices according to the present invention include simple rotary or linear brakes for controlling mechanical motions inside office equipment such as copiers or printers, e.g., paper feed mechanisms. Additional applications for magnetically actuated motion control devices according to the present invention include dampers for use as semi-active control elements in conjunction with ultra-low vibration tables and platforms. Magnetically actuated motion control devices according to the present invention can also be used as latching or locking mechanisms in office furniture, e.g., props and latches for doors, drawers, etc. Still other applications include exercise equipment, rehabilitation equipment, joysticks, control knob wheels, seismic structural control dampers, avionics semi-active control devices, machine tool fixturing devices, ventilation system flaps and doors in automobiles, door hinges and sliding doors in vehicles, etc.

Magnetically actuated motion control devices according to the present invention can also be used in the area of haptics. The field of haptics includes devices used in computer peripherals such as force-feedback steering wheels, control knobs, programmable detents, programmable endstops, computer pointing devices and joysticks used with games and other software. This field also includes industrial force feedback mechanisms such as steering wheels on steer-by-wire vehicles and rotating instrument control knobs.

Yet another application is to use either linear or rotary embodiments of the invention in conjunction with pneumatic and hydraulic actuators to enable precision position and velocity control.

Turning to the drawings, a first exemplary embodiment of a magnetically actuated motion control device according to the present invention is shown inFIGS. 1 and 2. The first embodiment motion control device is a damper101and includes a housing103defining a cavity105in which a piston107is located. The housing103includes a least one longitudinal slot109(five of eight such slots can be seen inFIG. 1). The housing shown inFIG. 1includes a plurality of slots that pass through the housing wall to define flexible bands, tabs, or fingers111. The slots109extend through the wall of the housing103and extend nearly the entire length of the housing103. Although narrow slots are illustrated in the Figures, it should be understood that a suitable wide slot could also be provided in the housing.

The piston107includes a shaft112having a magnetically active portion113made up of at least one, and preferably two electromagnetic coils115set in a magnetically permeable core117. Although here the magnetically permeable core117is hollow, the core can alternatively be a solid bobbin. A hollow core allows space for connecting wires or for an axial screw or rivet. However, a solid core is preferable because magnetic saturation of the core is reduced.

In addition, the core can be made up of a plurality of core pieces. A current source118supplies current to the coils115through wires119. Each end of the damper preferably includes a structure which facilitates attaching damper101to other structures, such as clevis eye121for attaching the end to a portion of a damped component.

Current flowing through the coils115creates a magnetic field that draws the housing103in toward the piston107. For this purpose, the housing103is formed of a material which will be attracted by the magnetic field. Examples include, but are not limited to, steels and other iron alloys. The amount of current flowing through the coils115is generally directly proportional to the magnitude of the magnetic field generated. Thus, control of the electric current flowing through the coils115can be used to control the normal or pressing force between the inner surface of the housing103and the outer surface of the piston107, thereby controlling the damping effect of the damper101.

An illustration of the damping effect can be seen in the end sectional view shown inFIG. 2, which shows the relationship of the slotted housing103with respect to the piston107. When no magnetic field is applied, the piston107, and particularly the active portion113, fits loosely within the housing103to define a small radial clearance123between the housing103and the magnetically active portion113of the piston107. That is, the housing103is relaxed and does not press against the piston107. When current is supplied to the coils115the magnetic field generated causes the flexible fingers111in the housing103to be attracted radially inward as indicated by the arrows125such that the housing103squeezes the piston107with a force proportional to the applied magnetic field, and therefore the applied current.

The slotted housing103and the core117of the piston107are preferably made from low carbon, high permeability steel, although other magnetically permeable materials can be used. The slots109are preferably evenly spaced around the circumference of the housing103so that axial-periodic symmetry is maintained. The pair of coils115is preferably wired such that they produce magnetic fields in opposite directions. This configuration allows the magnetic field produced by each coil115to add rather than cancel in an area between the coils115.

The configuration of the slots in the housing of the damper can be varied to tune the flexibility of a housing.FIGS. 3A and 3Billustrate a housing127that includes fewer longitudinal slots109, and therefore has less flexibility than a comparable housing having a larger number of slots. Longitudinal slots109may also be carried through to an open end129of a housing131as shown inFIGS. 4A and 4B. Slots109carried through to the end129create a flexible housing131which promotes full contact between the housing131and the piston when the magnetic field is applied. Such a slot configuration may be particularly useful when the housing131is made from a thick-wall tubing. Greater housing flexibility can also be obtained by connecting pairs of slots109in a housing133with a cross-slot135to form flexible fingers137having free ends138as shown inFIGS. 5A and 5B.

Depending on the thickness of the housing material and its consequent ability to carry magnetic flux (permeability), and also on the magnitude of the desired damping force, the number of coils115can vary from the embodiment shown inFIGS. 1 and 2. For example, a single-coil embodiment139is shown inFIG. 6and a 4-coil embodiment141is shown inFIG. 7. Except for the number of coils115, and a solid core143rather than the hollow core described above, the embodiments shown inFIGS. 6 and 7are identical to the embodiment shown inFIGS. 1 and 2. More coils115are preferable when the thickness of the housing is small in order to avoid magnetic saturation of the housing. Magnetic saturation refers to the maximum amount of magnetization a material can attain, as will be readily appreciated by one of ordinary skill in the art. The thickness of the housing limits the amount of magnetization that can be induced in the portion of the housing adjacent to the coils.

In some applications of the invention it is desirable to have the magnetic field, and therefore the damping force, applied most of the time with only short instances of turning the damping off. This can be accomplished by adding one or more permanent magnets to the system. A permanent magnet can be used in the damper so that the damper is in its on-state and the housing pressing against the piston when no current is applied to the electromagnetic coil. The electromagnetic coil serves to cancel the field of the permanent magnet as current is applied to progressively turn the damper off.

A seventh exemplary embodiment of the motion control device of the present invention is illustrated inFIG. 8. As seen inFIG. 8, two axially polarized (i.e., the opposite faces of the disks are the opposite poles of the magnets) disk magnets143are positioned and oriented to bias a damper145into an on-state, i.e., a condition in which the housing is magnetically attracted to the piston. A magnetically active portion147of a piston149includes three core pieces151between which the disk magnets143are located. The disk magnets143are located immediately radially inward of the coils115. The disk magnets143pull the housing103and the piston149together. In order to turn the damping off, the magnetic fields produced by the permanent disk magnets143are at least in part, and preferably completely canceled by applying current to the pair of coils115, which each generate magnetic fields that oppose those of the permanent magnets143.

An eighth exemplary embodiment of the motion control device of the present invention is illustrated inFIG. 9. In this case the electromagnets do not cancel the magnetic field in all directions. Rather, the electromagnets cause the field of the permanent magnet to be redirected to a different path.

Like the embodiment shown inFIG. 8, the embodiment of a damper150according to the present invention shown inFIG. 9includes the housing103having the same structure as that shown inFIGS. 1 and 2. According to the embodiment shown inFIG. 9, a magnetically active portion152of a piston153includes axially-polarized permanent ring magnets155located immediately radially inward of the coils115. The coils and ring magnets are located between magnetically permeable core pieces157so as to define non-magnetic gaps159in the center of each ring magnet155. Gaps159are less magnetically permeable than core pieces157, and therefore cause less magnetic flux through the center of the magnetically active portion152. The core pieces157and ring magnets155are held together by a non-magnetic connector161. The connector161is non-magnetic to prevent the generated magnetic field from being shunted away from the interface between the housing103and the magnetically active portion152. Alternatively, the core pieces157can be held together by an adhesive. Any suitable adhesive can be used, including but not limited to epoxys and cyanoacrylates.

As shown inFIG. 9, the non-magnetic gaps159at the center of the ring magnets155allow very little magnetic flux to follow flanking paths through the non-magnetic gaps159at the center of the ring magnets155. As a result, a magnetic field through the housing103has a much lower reluctance (resistance to carrying a magnetic field) than the flux path through the center of each of the ring magnets155and therefore radially draws the housing103and the piston together, as described above. In order to reduce the damping force, current is applied to the electromagnetic coils115which produce a magnetic field. The current can be adjusted such that the magnitude of the field produced by the coils is equal to, but opposite, that of the ring magnets155where the field paths cross into the housing103.

A ninth exemplary embodiment of the motion control device of the present invention is illustrated inFIG. 10. As shown inFIG. 10, a spring167can be added to an end of a damper according to the present invention to form a strut169. The damper shown inFIG. 10is identical in structure to that shown inFIGS. 1 and 2, except that the spring167is provided between the end171of the piston107and closed end173of the housing103. In a mechanical system the strut169provides the desired spring stiffness in addition to a controllable level of damping force. In addition, as schematically shown inFIG. 10, a mechanical stop175is added to the end of the housing103to hold the piston107in the housing103and allow the spring167to be preloaded. The mechanical stop175can optionally be included with damper embodiments as well.

Measured performance of a damper constructed according to the present invention is shown in the graph comprisingFIG. 11. For purposes of plotting the performance graph, the damper housing was constructed from low-carbon steel tubing having a 1.125 inch (28.58 mm) outer diameter and 1.000 inch (25.40 mm) inner diameter. The steel part of the housing was 5.0 inches (127 mm) long. Four lengthwise slits each approximately 0.040 inches (1 mm) wide 4.25 inches (108 mm) long were formed in the housing. The piston included two coils wound onto a low carbon steel double bobbin having an overall length of 1.0 inches (25.4 mm). The diameter of the steel poles of the piston was 0.990 inches (25.15 mm). The axial length of the two outer pole sections were each 0.145 inches (3.68 mm). The center pole section was 0.290 inches (7.37 mm) long. The diameter of the solid center core of the piston was 0.689 inches (17.5 mm). The two coils were each wound with 350 turns of 35 AWG magnet wire and were connected in series. The total resistance of the two coils was approximately 48 ohms. The total usable stroke of the damper was about 3 inches (76 mm).

Turning now to the graph, initially, at low current, the example damper displays a proportionate, nearly linear behavior which then rolls off as magnetic saturation effects begin to dominate as can be seen inFIG. 11. The damping force that is produced is almost perfectly coulombic with little or no velocity dependence. That is, the damping force is almost directly dependent on the current supplied to the coils. The data shown are peak forces obtained with the damper undergoing sinusoidal excitation with a ±0.5 inches (12.7 mm) amplitude and apeak speed of 4 inches/sec (102 mm/s). A curve obtained with a peak speed of 1 inch/sec (25.4 mm/sec) appeared to be nearly identical.

Although axial motion of the piston relative to the housing is what has been discussed thus far, a damper according to the present invention will also function as a rotary damper with the piston rotating relative to the housing. A tenth exemplary embodiment of the motion control device of the present invention is illustrated inFIGS. 12 and 13.FIG. 12shows an assembled example of a rotational embodiment according to the present invention, with portions broken away to show some interior elements.FIG. 13shows the embodiment shown inFIG. 12partially disassembled. In this embodiment a coil177wound around a center steel bobbin179form a circular stator181. The stator181is positioned within a cavity defined by, and for rotation relative to, a slotted housing183. Slots185are connected by cross-slots186to define fingers187, which impart a high degree of flexibility to the housing183. The highly flexible finger187of highly flexible housing183allow contact between the stator181and the housing183when the magnetic field is energized. Bearings188are included in the stator181to support a shaft190with which the housing183rotates. Bearings188allow the circular housing and shaft190to rotate around circular stator181. As shown inFIG. 13second member circular stator181is received in the cavity between the outer perimeter of the first housing member and the inner shaft190. As shown inFIG. 12, the housing encircles the stator181received in the cavity around the shaft190. The flexible finger187is movable into frictional contact with the outer circumference surface of circular stator181when a current from current source118generates a magnetic field with coil177. The magnetic field generator of the circular stator181with the bobbin and wound coil generates a magnetic field that pulls the finger187inward and into frictional contact to produce frictional damping of the relative rotation between the housing and the stator.

A damper according to the present invention generates strong coulombic pressing forces when the outer surface of the magnetically active portion of the piston or stator makes direct contact with the inner surface of the steel housing finger. In fact, the inventor herein has found that damper performance actually improves after being initially operated due to an apparent “wearing-in” process. During the wearing-in process friction between the surfaces of the housing and the piston causes some wear to occur which effectively laps or burnishes the contacting surfaces such that “high spots” (large surface features) are removed and the housing and piston (or stator) contact more intimately. This improves the efficiency of the magnetic circuit and increases total contact surface area so that the overall damping force is increased.

In some applications of the present invention, it is desirable to place a layer of damping material or acoustic foam189around the outside of the housing as seen on the exemplary damper shown inFIG. 14. The components of the damper shown inFIG. 14are identical to the exemplary dampers discussed with respect toFIGS. 1-13. Such an acoustically insulating material will serve to attenuate any high frequency squeaking, rubbing or clanking sounds that may occur due to a metal housing moving against a metal piston. The desirability of such added acoustic material depends on a number of factors, including: the actual thickness of the housing; the resonant characteristics of the housing; the looseness of the fit between the housing and the piston, the alignment of the parts during application of the damper; and the presence of elastomeric bushings in the clevis eyes used to mount the damper. Lubricant (grease or oil) can also be added so that the parts of the damper slide smoothly relative to each other in the off-state. Suitable acoustic material will be readily apparent to one of ordinary skill in the art.

A similar quieting effect can be achieved by adding an intermediary friction increasing layer to the rubbing surfaces of the piston or stator, or the inner surfaces of the housing. Examples of such materials may be a thin polymeric layer such as polyethylene or nylon, or a composite friction material such as that typically used in vehicle clutches and brakes. Such a friction layer eliminates metal to metal contact and reduces long term wear. However, the presence of such layer of friction material will in general make the magnetic circuit less efficient. Unless the friction material has a high permeability like low carbon steel it increases the reluctance of the magnetic circuit dramatically and lowers the amount of damping force when the damper is in the on-state.

According to yet another embodiment of the present invention, a magnetically controlled damper can further include an integrated position sensor. Exemplary embodiments of a damper including a position sensor according to the present invention are shown inFIGS. 15-22and49. Preferably, a magnetic friction damper191includes sensor193, such as a linear potentiometer, including a first portion194and a slider196. The first portion is attached to the housing103by brackets198. The slider196is coupled to the damper piston195by a small engagement pin197that passes through one of a plurality of slots109in the housing103of the magnetic friction damper191. Preferably in rotational embodiments of the invention a rotary position sensor is utilized, such as a rotary potentiometer.

An eleventh exemplary embodiment of the motion control device of the present invention is illustrated inFIGS. 15-17.FIGS. 15-17show a damper similar to the damper shown inFIGS. 1 and 2. Otherwise identical to the piston shown inFIGS. 1 and 2, the piston195includes a circumferential groove199between electromagnetic coils115. The sensor193is mounted along the side of the damper housing with brackets198such that an extension, such as the pin197of the slider196on the potentiometer193, can pass through one of the longitudinal slots109in the damper housing103. The groove199in the damper piston195accepts the pin197and causes the slider196to move longitudinally in concert with the piston195while permitting relative rotational movement between the piston and the housing. Thus, for example, electrical resistance of a potentiometer varies in proportion to the piston displacement in the housing, thereby indicating the relative position of the housing103and the piston195.

Alternatively or in addition to measuring linear displacement with the sensor193, the sensor can be used to measure the relative velocity or acceleration of the housing103and the piston195. Furthermore, sensor193can be a velocity sensor or an accelerometer, which are readily commercially available and with which one of ordinary skill in the art is well acquainted. A device for interpreting the signal from sensor193, such as a general purpose computer200having a memory201, is in electrical communication with electrical connections202on the sensor193. Computer200can further be provided with logic in the memory201which can determine relative position, velocity, or acceleration based on the electrical signals sent by the sensor193, and can store data representative of one or more of these parameters. Because one of ordinary skill in the art readily appreciates the details of the use of such a computer200and logic usable with sensor193, further details will not be provided herein.

A circumferential groove199rather than a hole in the piston195is preferred because the circumferential groove199does not inhibit rotational motion of the piston195. Allowing free rotational motion of the piston195relative to the housing103is important so that the clevis eyes121at the ends of the damper191, when provided, can be easily properly aligned with the mounting pins in the components to which the damper191is attached so that the damper191does not bind during use.

Twelfth, thirteenth and fourteenth exemplary embodiments of the motion control device are illustrated inFIGS. 18,19and20respectively. As seen inFIGS. 18-20, a circumferential groove can be located on other parts of the piston195as well. For example, as seen in the embodiment shown inFIG. 18, a groove203is formed into the shaft of the piston195just behind a magnetically active portion205of the piston. In the embodiment shown inFIG. 19, a groove207is formed between a lip209formed into the piston195and a rear end211of the magnetically active portion205of the piston195. In the embodiment shown inFIG. 20, a disk-shaped member213is attached to a free end215of the piston195to define a groove217. Other than the arrangement of the circumferential groove the embodiments shown inFIGS. 18-20are identical to the embodiment shown inFIGS. 15-17.

An experimental example of a damper including a position sensor was tested by the inventor herein. The prototype utilized a Panasonic potentiometer (part number EVA-JQLR15B14, Matsushita Electric (Panasonic U.S.A.), New York, N.Y., U.S. distributors include DigiKey and Newark Electronics) with a working stroke of 3.94 inches (100 mm). Electrical resistance varied linearly from 0 to 10 Kohms. The potentiometer was mounted to the damper housing using hot-melt adhesive. The original rectangular extension on the slider was modified into the form of a small diameter pin to fit through one of the longitudinal slots in the magnetic friction damper housing. In the example, the groove in the piston was made by adding a small, spaced plastic disk to the end of an existing piston as shown inFIG. 20. The final result was an integrated variable resistance sensor whose output varied linearly with the position of the damper piston. Further, the pin and groove geometry allowed free rotational motion of the piston within the housing, a feature that allowed for proper alignment of the clevis eyes during damper installation and use.

A fifteenth exemplary embodiment of the motion control device of the present invention is illustrated inFIGS. 21 and 22. Another exemplary embodiment of a damper including a position sensor is shown ifFIGS. 21 and 22. In this embodiment a rotary sensor219(e.g., a rotary potentiometer) is used in the position sensor. Alternatively, a rotary optical encoder can be used in the position sensor. The rotary sensor219is mounted to the housing by a bracket220and is coupled to the motion of a piston221by means of the integrated rack and pinion system223. A pinion gear225is coupled to the rotary sensor219(or optical encoder) by an axle227. The piston221includes a shaft228that is molded (of, e.g., plastic) or otherwise formed to include a rack229. It is preferable to allow relative rotation between the piston and the pinion gear. Therefore, it is preferable that the rack229is formed around the entire circumference of the piston221.

In addition to the variable resistance sensors discussed above, other sensing devices may alternatively be used, including variable inductance or variable capacitance sensors, optical encoders, flex or bend sensors etc. and are all within the spirit and scope of the present invention. As discussed in reference toFIGS. 15-22a sensor can be used to measure relative velocity or acceleration as well as relative position between a piston and a housing.

Further, although the magnetic damper including a position sensor has been described in the context of collet type dampers, the same position sensors may be included with MR or ER dampers. Examples of such MR or ER dampers are described in U.S. Pat. Nos. 5,284,330, 5,277,281 and 5,018,606, which are herein incorporated by reference in their entireties.

Magnetically actuated motion control devices according to the present invention, including those described herein, are useful in many applications.FIGS. 23-31illustrate a number of exemplary applications for the present invention device. For example,FIG. 23shows the use of magnetically controllable dampers according to the present invention230in a washing machine231. Magnetically controllable friction dampers can provide a high level of damping when the washing machine231passes during a resonance cycle and can be turned off during high speed spin to provide optimum isolation of the spinning basket or drum232.

FIG. 24shows several possible uses of the present invention in an automobile, truck, or other vehicle. Magnetically actuated motion control devices according to the present invention can be used as a semi-active seat suspension when located between a seat233and an associated base235. Dampers according to the present invention can also be used as a locking element237in a steering column239including tilt and telescope mechanisms241,243. A magnetically actuated motion control device230in its on-state locks the steering column239in place. In its off-state, the damper allows the steering wheel to tilt and telescope into a desired position. Other applications in motor vehicles include the use of a damper as an interlock mechanism in gearshift mechanisms (not illustrated).

Another application for the invention is as a locking member245for various types of furniture such as office chairs, for example.FIG. 25Aillustrates the use of a magnetically actuated motion control device230in a height adjustor245of an office chair247.FIG. 25Billustrates the use of a magnetically actuated motion control device230as a locking mechanism249for the back tilt motion of the chair247and as a locking mechanism250for a height adjustable armrest252of the chair247, and which can be connected between the armrest252and either a seat254or a backrest256of the chair247. An electrical control251is used by an operator to selectively turn off the magnetically actuated motion control device230, thereby allowing the chair247to tilt.

FIG. 26illustrates the use of magnetically actuated motion control device230as a locking mechanism253for an adjustable height table255. The adjustable height table255also includes a control258wired to the locking mechanism253. The control258selectively allows selective locking of the adjustable table255by alternatively turning the dampers on and off.

FIGS. 27A and 27Bshow a magnetically actuated motion control device230according to the present invention used as a locking mechanism for a tilting work surface257into position (FIG. 27B) or for locking a flipper door259into place (FIG.27AA).

Another area of application for the motion control device of the present invention is the area of haptics, where a linear or rotary embodiment of the invention may be used to provide tactile force feedback to an operator.FIG. 28illustrates a force-feedback steering wheel261that uses a rotary damper263, such as that described in reference toFIGS. 12 and 13. Such a device can also be used in “steer-by-wire” mechanisms on vehicles such as cars, trucks or industrial jitneys and forklifts. The present invention can also be used in computer games as a force-feedback steering wheel that is responsive to virtual action in a game. In the example shown inFIG. 28, the damper263is coupled to a rotary position sensor265so that the damping can be coupled to the position of the steering wheel. Similarly a control knob wheel261can be provided with programmable end stops, with a rotary position sensor sensing the position of the rotor and an end stop then being generated by generating a magnetic field to stop further rotation in the rotating direction.

The present invention can also be used as a small controllable friction brake inside computer pointing devices, such as a computer mouse267as shown inFIG. 29. The mouse267includes a mouse ball269that is in rolling contact with a y-drive pinion271and an x-drive pinion273. The drive pinions271,273are each respectively coupled to a y-encoder wheel275and an x-encoder wheel277with a rotary brake279of the type described in reference toFIGS. 12 and 13, for example. Each encoder wheel275,277is positioned so as to rotate through an encoder sensor280. The rotation of an encoder wheel is sensed by a respective encoder which sends an electrical signal representing the movement of the mouse ball273in an x-y plane which passes through pinions271,273.

The invention can also be used to provide an active force feedback steering wheel281as shown inFIG. 30. In this application a pair of clutches283,285, similar in structure to the rotary damper described with reference toFIGS. 12 and 13, are used to selectively couple the steering wheel281to either clockwise or counter-clockwise rotating housings287,289. In a clutch arrangement, the stator and the housing are each rotatable, and are rotatable relative to one another. A motor291is coupled to clockwise and counter-clockwise housings287,289by a pinion drive293. A shaft295extending from the steering wheel passes through the housing289and is coupled to stators297,299of the clutches283,285, respectively. The shaft295can include bearings or other similar structures where the shaft passes through the housings287,289, to permit relative rotational movement between the shaft and the housings. A rotary position sensor298is coupled to the end of shaft295to detect the rotation of the steering wheel281. The stators297,299, provide friction damping in the clockwise and counter-clockwise directions as in the manner described with reference toFIGS. 12 and 13with contact surfaces301,303. Thus, the steering wheel281can actually be forced to turn with a prescribed amount of force in either direction with the ultimate driving source being a simple single direction motor291.

The invention can also be used in flexible fixturing systems such as the fixturing system305, schematically illustrated inFIG. 31. In this example, an array of struts307, like those described in reference toFIG. 10, are each coupled to extensions309and are used to hold an irregularly shaped object311in position for machining or gauging of the object311. Each of the struts307can selectively lock or release an extension309so that objects of various sizes and shapes can be accommodated and held in place.

In addition to the embodiments of the present invention shown inFIGS. 1-22and described hereinabove, other embodiments of the present invention shown inFIGS. 32-49can be interchanged for the exemplary magnetically actuated control devices illustrated in the applications described with reference toFIGS. 23-31.

The sixteenth preferred embodiment of the motion control device is illustrated inFIG. 32. As seen inFIG. 32, the motion control device is comprised of a damper313that includes a housing103having slots109and a piston315having a magnetically active portion317that includes a permanent disk magnet319sandwiched between core pieces321. The core pieces321are held together by the magnetic field generated by the permanent magnet319, eliminating the need for connectors or adhesives in the magnetically active portion of the piston315. Thus, the assembly of the damper313is greatly simplified. Because the magnetic field generated by the permanent magnet319cannot be varied, the damper313is always in an on-state. That is, the housing103always squeezes the piston315with the same force.

Seventeenth and eighteenth exemplary embodiments of the motion control device of the present invention are illustrated inFIGS. 33 and 34. However, as seen inFIGS. 33 and 34, the squeezing force between the housing and the magnetically active portion of the piston can be varied by introducing a variable width gap into the magnetically active portion of the damper. As seen inFIG. 33, a damper323of this type includes a housing103including a plurality of slots109, within which a hollow piston325is located. A magnetically active portion326of the piston325includes an end327connected to a control rod329. The end327includes an axially polarized disk magnet330that is sandwiched between a cap piece332and a first pole piece331. The control rod329is attached to the cap piece332.

According to an exemplary embodiment shown inFIG. 33, a second pole piece333is attached to the hollow piston325. A clearance335between the control rod329and the second pole piece333allows the second pole piece333to slide relative to the control rod329. A lever337located on the outer surface of the piston325is connected to the control rod329through an opening338in the piston325so that as the lever337is turned, the control rod329pushes the end327of the magnetically active portion326toward or away from the second pole piece333attached to the hollow piston325. In this way, an air gap339of variable size is introduced into the magnetically active portion326. The gap339increases the reluctance within the magnetically active portion326, thereby diminishing both the force with which the housing103squeezes the piston325, and also the frictional damping force produced by the damper.

Alternatively, as seen inFIG. 34, a damper341according to the present invention can include a control rod343having a threaded end345that threads into a tapped second pole piece347that is attached to the hollow piston325. Like the embodiment shown inFIG. 33, the control rod343is attached (at the threaded end345) to a cap piece349that sandwiches an axially polarized disk magnet350with a first pole piece351. The control rod343is connected to a knob353that is exposed through an opening355in the hollow piston325. Rotating the knob353rotates the control rod343and causes the tapped second pole piece347to move relative to the cap piece349. In this way, a variable air gap357is introduced into the magnetically active portion. As discussed in reference to the embodiment shown inFIG. 33, the variable gap357can be used to control (diminish) the damping force produced by the damper.

Nineteenth and twentieth exemplary embodiments of the motion control device of the present invention are illustrated byFIGS. 35A-36B, and37A-37B respectively. As seen inFIGS. 35A-37B, according to the present invention the components of a magnetically actuated motion control device can be reversed with respect to the other exemplary embodiments discussed thus far. For example, as seen inFIGS. 35A and 35B, a damper359includes a housing361that defines a cavity363in which a piston365is located. The piston365includes four slots367that extend from an open end369of the piston365. Although the piston365is tubular, a piston can have any suitable cross-sectional area such as square, cylindrical etc. A magnetic field generator, such as coils371(shown schematically), is located in a magnetically permeable assembly373having pole pieces375. At least a portion of the slotted piston365is magnetically permeable so that when a magnetic field is generated by the coils371, the piston flexes and presses outward against the pole pieces375of the magnetic assembly371located on the housing361. Accordingly, the friction damping force can be controlled by controlling the magnetic field generated by the coils371.

As seen inFIGS. 36A and 36B, the piston365is hollow. A hollow piston is preferred because a hollow piston can easily flex outward in response to an applied magnetic field. However, according to an embodiment shown inFIGS. 37A and 37B, a piston377can be solid. Slots379extend through the solid piston377to define bands, sections, tabs, or fingers381. The fingers381flex outward in response to an applied magnetic field to produce a frictional damping force. An advantage of having a solid piston is that magnetic saturation of the piston can be mitigated.

Other embodiments of a magnetically actuated motion control device according to the present invention include bearing components that contact the components of the magnetically controlled motion control device, e.g., a housing and a piston, and provide smooth relative motion between the components when the motion control device is in its off-state.

For example, a twenty-first exemplary embodiment of the motion control device of the present invention is illustrated in FIGS.20and38-40C. A magnetically actuated motion control device383includes a piston385which fits within a housing387. The piston385includes one or more longitudinal slots388which extend through an end389of the piston385to define one or more fingers390. The housing387includes magnetic field generators, such as coils391, mounted between pole pieces393. The housing387defines a cavity395connecting opposing open ends397,399of the housing387. In this way, the piston385can pass through both open ends397,399of the housing387during its stroke. Accordingly, the axial length of the housing387can be much shorter than the axial length of the piston385, thereby providing a compact device. Trunnion mounts401, which extend from the housing387, allow the open ended housing387to be mounted to a separate device.

Turning to a partial view38A, a bearing assembly403is located radially inward of each of the coils391and within radial grooves404defined by the pole pieces393of the housing387. Each bearing assembly403includes an annular spring405(see also,FIG. 40B) located between a coil391and an expandable bearing407. Preferably, the spring is a band of compliant, elastomeric material, e.g., a sponge material or an O-ring.

The expandable bearing407contacts the surface of the piston385and is biased by the spring405radially inward toward the outer surface of the piston385. As a result, a small gap409is maintained between the housing387and the piston385when the coils391are not energized. Preferably, the radial thickness of each bearing407is greater than the thickness of the gap409so that the bearing remains captured within the respective radial groove404. Preferably, only the bearings407contact the outer surface of the piston385when the magnetically actuated motion control device is in its off-state. By spacing a plurality of bearings407axially along the housing387, the piston385and the housing387are prevented from binding, or moving out of axial alignment relative to one another (also referred to as “cocking”) when the device is in an off-state.

Energizing the coils391causes the fingers390to flex in a radially outward direction and press against the inner surface of the housing387. At the same time, each bearing407is pressed outward by the fingers390, thereby compressing the spring405. Thus, when the motion control device383is in its on-state, the gap409between the housing387and the piston385is eliminated as seen inFIGS. 39,39A and40A as the magnetic field generated by the coils391causes the housing387and the piston385to press firmly against one another.

In order to provide firm contact between the housing387and the piston385, the bearing407must expand radially as the fingers390flex toward the housing387in response to a magnetic field generated by the coils391. As seen inFIG. 40C, one embodiment of the annular bearing includes a split411to allow for radial expansion. Optionally, split411can be eliminated by forming bearing407of a material flexible enough to permit its radial expansion. Preferably, the bearing is made from a strip of flexible, low friction material. Examples of suitable bearing materials include nylon materials, e.g., molybdenum disulfide filled nylon fibers, Hydlar HF (A.C. Hyde Company, Grenloch, N.J.), which is a material including nylon reinforced with Kevlar fibers, polytetrafluorethylene materials, e.g., Teflon®, Derlin AF® (E. I. Dupont Nemours and Co., Wilmington, Del.), which is teflon filled with an acetal homopolymer, and Rulon® (Dixon Industries, Bristol, R.I.), which is a material including Teflon® reinforced Kevlar® fibers, Vespel® (E. I. Dupont Nemours and Co., Wilmington, Del.), which is a polyimide material, Ryton® (Philips Petroleum Co., Battlesville, Okla.), which is a material including polyphenylene sulfide filled with carbon fiber, or brass. The preceding list is not exhaustive, and other suitable materials will be apparent to one with ordinary skill in the art.

As explained earlier, the magnetic field generators, e.g., coils can be mounted to either the housing or the piston with the other of the housing or the piston being split into one or more flexible fingers.FIG. 41shows a twenty-second embodiment of the present invention including a piston413having two magnetic coils391located within a core414and a slotted housing415in which the piston413is located. Like the embodiments discussed in reference toFIGS. 1 and 2, the housing415includes one or more longitudinal slots417that define one or more flexible fingers419.

The piston413slides within the housing415on bearing assemblies421, which are each located radially inward of the coils391and bear against the inner surface of the housing415. Each bearing assembly includes an annular spring425, which is located between an annular bearing427and one of the respective coils391. The spring425biases the bearing427radially outward and away from the magnetically active portion of the piston to create a gap428between the outer surface of the piston413and the inner surface of the housing415. Preferably, each bearing427and spring425are of the same structures and materials as those discussed in reference toFIGS. 38-40.

According to a twenty-third exemplary embodiment shown inFIG. 42, bearing assemblies are located axially spaced from coils391. In this embodiment a piston429is located within a housing430having structure such as that described in reference toFIG. 41, including slots432defining one or more fingers434. The piston429includes a main body431having a shoulder433at one end, an end cap435including a shoulder436that opposes the shoulder433and two steel cores437sandwiched between the end cap435and the main body431.

A first bearing assembly439is located between the cores437and the shoulder433in the cores437. A second bearing assembly441is located between the shoulder436and the main body431. Each bearing includes a spring438that biases a bearing440against the inner surface of the housing430. Preferably, the spring438and bearing440are constructed in the same manner as described with respect to the previous embodiments. The bearings440are biased against the inner surface of the housing430to create a gap442between the cores437and the inner surface of the housing430when the coils are not energized, i.e., the magnetically actuated motion control device is in an off-state.

The cores437are secured to the main body of the piston429by an interference fit between the outer surface of the cores437and the inner surface of the piston429. The cores437and end cap435are secured to one another by a bolt443and a nut445. The bolt443passes through aligned bores in the cores437and the end cap435. Accordingly, as exemplified by this embodiment, the bearing assemblies need not be located between the magnetic field generator (e.g., coils391) and the opposing slotted member.

While two magnetic field generators, e.g., coils391, are illustrated inFIGS. 38-41, one of ordinary skill in the art will readily appreciate that one, or three or more, magnetic field generators may alternatively be used within the spirit and scope of the invention. Similarly, although two bearing assemblies are illustrated inFIGS. 38-41one or more bearing assemblies may be used within the spirit and scope of the invention.

Advantages of using bearing assemblies in a magnetically actuated motion control device in order to create a gap between the housing and the piston include maintaining the piston and the housing in axial alignment and creating smooth, fluid-like, relative movement between the housing and the piston while the damper is in its off-state. An example of a situation in which it may be important to provide smooth movement between the housing and the piston is when an embodiment of the present invention is used as a locking mechanism in a hinged vehicle door. In the example shown inFIG. 43, a car447includes a body449and a door451that swings on a hinge453relative to the body449. The housing387of a motion control device383(shown inFIGS. 39-40C) is mounted in the door451of the car447. Because the door451has limited space in which to fit extra components, the housing387is preferably short relative to the length of the piston385. The slotted piston385is attached at one end to the body of the car. As the door is swung open and closed, the piston385moves within the housing387. An operator can lock the door451into any position by activating a switch455which energizes the magnetic field generator to cause the piston and the housing to press against one another together, thus holding the door in position. Similarly the rotational embodiments of the present invention are utilized to hold the vehicle door in position and control the motion of the door relative to the vehicle body with magnetic actuation of the finger towards the stator. The rotational embodiments of the invention are utilized to contol the rotating motion of a hinge. The shaft190can be directly coupled and connected to the rotating hinge members or indirectly coupled, such as with meshing gears. A rotary position sensor is preferably utilized to sense the rotating motion of the hinge and the control device.

The invention includes a magnetically actuated motion control device. The magnetically actuated motion control device is preferably comprised of a first housing member defining a cavity with the first housing member including a movable flexible finger. The magnetically actuated motion control device is preferably comprised of a second member positioned within the first housing member cavity with the first housing member movable relative to the second member with a magnetic field generator located on the second member. The magnetic field generator causes the movable flexible finger to press against the second member to produce frictional damping. In a preferred embodiment the second member is a stator having a center axis with the stator and the first housing being relatively rotatable around the central axis. Preferably the housing encircles the second member with the housing relatively rotatable around the second member. Preferably the movable flexible finger has a tab end for attachment with the first housing member. In an embodiment the movable flexible finger has a free end and a distal attached end which is attached to the first housing member, preferably with the distal attached end comprised of a tab end. In an embodiment the movable flexible finger has a first tab end and a distal second tab end.

FIGS. 12-13and44-51show rotational embodiments of the magnetically actuated motion control device. The magnetically actuated motion control device is preferably comprised of a first housing member183defining a cavity184with the first housing member including a movable flexible finger187. The magnetically actuated motion control device is preferably comprised of a second member181positioned within the first housing member cavity184with the first housing member183movable relative to the second member with a magnetic field generator177located on the second member. Preferably the second member181is a magnetic field generator stator formed from a center bobbin179and a coil177wrapped around the bobbin to produce a magnetic field when a current is supplied to the coil from a current source118. The magnetic field generator causes the movable flexible finger187to press against the second member181to produce frictional damping. In a preferred embodiment the second member181is a stator having a center axis182with the stator and the first housing being relatively rotatable around the central axis. Preferably the housing183encircles the second member181with the housing rotatable around the second member. In an embodiment the movable flexible finger187has a free end501and a distal attached end503which is attached to the first housing member183. Preferably the first housing member includes a slot opening185. In a preferred embodiment the movable finger187extends through first housing member opening185with at least one tab end503. Preferably the movable finger is a circular finger band187that encircles the stator181. In an embodiment the movable circular band finger187has a free end501and a distal second end503. Preferably the distal second end503is comprised of a tab, with the distal second end tab extending through the opening slot185. As shown inFIGS. 47A and 48Asuch a motion control device with a free end501and a tab end503is preferred when the motion control device is intended to control motion in one direction of rotation. As shown inFIGS. 47B and 48Bsuch a motion control device with a first tab end503and a second tab end503is preferred when the motion control device is intended to control motion in two directions of rotation. Preferably the end tab is contained in the opening slot in which it is movable. The finger187rotates along with the housing183. Preferably the circular band finger187rotates with the circular cup housing183, with the finger band pulled around by the housing slot185. In preferred embodiments the band finger187is magnetic and the rotor cup housing and the rotor shaft190is preferably nonmagnetic. Preferably the band finger encircles at least 70%, more preferably at least 80%, more preferably at least 90%, most preferably at least 95% of the outer circumference of stator181. An air gap between the movable finger187and the second member181when a magnetic field is not generated by the magnetic field generator allows for relative movement between the first housing183and the second member181without frictional damping and contact between the housing finger and the second member. Preferably the movable finger187encircles the second member181with a gap505between the movable finger and the second member when a magnetic field is not generated by magnetic field generator stator coil. Preferably the first housing member is comprised of a rotor cup having a rotor cup outer perimeter507and a rotor cup inner shaft190, with the second member181received in cavity184between the rotor cup outer perimeter507and the rotor cup inner shaft190. Preferably the first housing member183has an inner shaft190and a cavity184for receiving the second member181with the second member stator received in the cavity between the finger187and the inner shaft. Preferably the first housing member inner shaft190is separated from the second member181with a bearing188. Preferably the movable finger187is a circular band that substantially encircles the outer circumference stator181. The second member circular stator outer circumference provides for contact with the finger187of housing183.

The invention includes a magnetically actuated motion control device comprised of a first housing member including a cavity formed therein and including a movable finger; and a second member disposed in the cavity; and at least one magnetic field generator mounted to cause the movable finger to be displaced toward the second member and thereby squeeze the second member. In a preferred embodiment the first housing member has an outer perimeter and includes a shaft, with the cavity for receiving the second member between the outer perimeter and the shaft.

As shown inFIGS. 12-13and44-48first housing member183has an outer perimeter507and an inner shaft190that provides a cavity184for receiving second member circular stator181. A movable finger187frictionally engages the second member stator181when it is magnetically attracted by the magnetic field generated by the stator. Preferably the first housing member is a rotor cup having a rotor cup with a rotor cup inner shaft. Preferably the first housing member inner shaft190is separated from the second member stator181with at least one bearing188. The stator181has a center axis182and includes a center steel bobbin179and a wound coil177for generating the magnetic field. The generated magnetic field pulls the finger187into contact with the circular stator outer circumference.

The invention includes a method of controlling relative motion between a first housing and a second member, with the housing having a finger movable relative to the second member, and the housing defining a cavity in which the second member is located. The invention includes generating a magnetic field and pressing the finger against the second member in accordance with the generated magnetic field.

The invention includes a method of controlling relative motion between a housing183having a finger187and a second member181, with the second member movable relative to the housing and finger, and the housing183defining a cavity184in which the second member is located. The invention includes generating a magnetic field and pressing the finger187against the second member181in accordance with the generated magnetic field. Preferably the second member181is a circular stator including a bobbin179and a coil177and said housing183includes a shaft190and the finger187is magnetically permeable wherein generating a magnetic field includes supplying a current from a current source118to the coil to attract the finger towards the circular stator. Preferably the finger187is formed from a material attracted by magnetic fields, and is able to carry a magnetic flux. Preferably the method includes rotating the circular stator relative to the housing with a bearing between the stator and the shaft. Pressing the finger187against the second member includes collapsing the finger around the circular stator. Preferably the finger187is a circular band, more preferably a notched circular band with flex link notches509along its outer circumference, preferably with the finger flex link notches509in parallel alignment with the central axis182and normal to the direction of rotation. As shown inFIG. 45A-B, finger187includes outer circumference flex link notches509in parallel alignment with central axis182and normal to the direction of rotational motion to provide for finger flexibility and frictional engagement of the finger with the second member upon generation of the magnetic field. In a preferred embodiment the invention includes providing a finger187with a plurality of flex links509spaced along the circumference of finger187. In embodiments as shown inFIG. 45C-D, the circular band fmger187includes flex links509between magnetic finger segments511. Magnetic finger segments511are preferably steel segments that are drawn inward toward the second member upon generation of the magnetic field, with the plurality of magnetic finger segments511linked together with the flex links509to form the magnetically actuatable movable finger187. As shown in the view of magnetically actuatable movable finger187inFIG. 45D, the flex links509form a web belt to contain and position the plurality of magnetic finger segments511, such as the circular band finger formed from an a flexible plastic belt with magnetically attractable steel magnetic finger segments511attached thereto between flex links509, such as with the finger segments511adhered thereto, snapped into place, or molded into the belt. In an embodiment the finger links509comprise a molded plastic belt with sockets that accept the magnetic finger segments511and contain and position the magnetic steel finger segments511around the finger187to form the magnetically actuatable movable finger which frictionally engages the second member upon generation of the magnetic field.

The invention includes a system with a magnetically actuated motion control device with a finger187frictionally engaging a circular stator181to control a rotational motion of the system. The magnetically actuated motion control device is coupled to a shaft with a wheel, with the circular stator or the housing being rotatable relative to the shaft. In a preferred embodiment the wheel and shaft is comprised of a control knob. Preferably the system includes a rotational sensor193that tracks rotation. Based on the sensor output a magnetic field is generated by the stator181to move finger187to make a rotation end stop.

The invention includes a vehicle447including a body449and a door451. The door451is attached by hinge453to the body frame449. The invention includes a magnetically actuated motion control device housing183mounted between the door451and the body449to magnetically control a movement of the door451relative to the body451. A second member stator181is received in a cavity184inside housing183. Rotary position sensor193is mounted with the housing183to sense rotation movement of the device and the hinge. The second member stator181has a center axis182, with the stator and said first housing183being relatively rotatable around the central axis.

The invention includes a vehicle447a body frame449and a door451. The door451is attached by a hinge453to the body. The invention includes a magnetically actuated motion control device comprising a first housing member183defining a cavity184. The first housing member183includes a movable finger187and a second member181is positioned within the first housing member cavity184, with the second member181movable relative to the first housing member183and includes a magnetic field generator which causes the movable finger187to press against the second member181to produce frictional damping with said magnetically actuated motion control device mounted to control a positioning of the door451relative to the body449. Preferably the movable finger187is a circular band that encircles the second member. Preferably the second member is a stator having a center axis182, and includes a bobbin179and a coil177, preferably with the stator being a circular stator with an outer circumference.

The invention includes a body frame449and a door451with the door being attached by a hinge453to the body frame449and a magnetically actuated motion control device with a first housing member183defining a cavity184. The first housing member183includes a movable finger187and a second member181positioned within said first housing member cavity184, with the second member movable relative to said first housing member. The second member181includes a magnetic field generator with the magnetic field generator causing the movable finger187to press against the second member181to produce frictional damping with the magnetically actuated motion control device mounted to control a positioning of the door451relative to the body frame449.

The invention includes a magnetically actuated rotary motion control device comprising a first housing member183including a cavity184formed therein and including a movable finger187with a plurality of flex links509. The magnetically actuated rotary motion control device includes a second member181disposed in the cavity184and at least one magnetic field generator mounted to cause said movable finger187to be displaced toward said second member181and thereby squeeze said second member. Preferably the second member181is comprised of a stator that includes the at least one magnetic field generator, with the stator181having a coil177wound around a center bobbin179such that a current through the coil177generates the magnetic field that attracts movable finger187toward second member stator181. Preferably the movable finger187with flex links509is a circular band finger. Preferably the stator181is a circular stator with the stator having an outer circumference and the movable finger187is a circular band and encircles at least seventy percent of the second member stator outer circumference.

The invention includes a magnetically actuated rotary motion control device comprising a first housing member183including a cavity184formed therein and including a movable finger187. The magnetically actuated rotary motion control device includes a second member181having an outer circumference and is disposed in the cavity184with the movable finger187encircling at least seventy percent of the second member outer circumference. The magnetically actuated rotary motion control device includes at least one magnetic field generator mounted to cause said movable finger187to be displaced toward said second member outer circumference and thereby squeeze said second member181. Preferably the second member181is comprised of a stator that includes the at least one magnetic field generator, with the stator181having a coil177wound around a center bobbin179such that a current through the coil177generates the magnetic field that attracts movable finger187toward second member stator181. Preferably the movable finger encircles at least eighty percent of the second member outer circumference. Preferably the movable finger encircles at least ninety percent of the second member outer circumference. Preferably the movable finger encircles at least ninety five percent of the second member outer circumference. Preferably the movable finger187is a circular band finger, preferably with flex links509.

The invention includes a haptic system comprising a control knob261that provides tactile force feedback to an operator with programmable virtual hard end stops. As shown inFIG. 50A-Dthe magnetically actuated rotary motion control device provides a haptic control knob261with tactile force feedback of the rotating control wheel knob including programmable virtual hard stops. The control knob system includes a first member circular band movable finger187and a second member base515with said control knob261rotatable relative to the base. The control knob system includes a rotational sensor265positioned to sense a positional characteristic of said rotatable control knob261relative to the base515. The base515includes a circular stator181for generating a magnetic field to cause the movable finger187to press against the second member stator base to produce frictional damping to inhibit rotation of the control knob261relative to the stationary base. Preferably the stator generates the magnetic field based on a positional characteristic of the rotating control knob261sensed by sensor265. Preferably the sensor265is comprised of an optical encoder, preferably a high resolution optical encoder with a resolution of at least 100 code positions per rotation (complete turn of 360 degrees), preferably at least 150 code positions per rotation, such as high resolution miniature optical encoders Grayhill Inc. Series 63Q and 63T. As shown in FIG.50, the sensor265senses the rotational position and rotational motion of the control knob261, with a current controllably supplied to the coil177to generate a magnetic field that draws the first member finger187into contact with the second member stator181in order to provide haptic feedback relating to the rotation of the control knob261relative to the base, including detents and hard stops of the control knob.

The invention includes a magnetically actuated rotary motion control device. As shown inFIG. 51, the magnetically actuated rotary motion control device includes a first housing member183including a cavity184formed therein and including a circular band movable finger187. The magnetically actuated rotary motion control device includes a second member181disposed in the cavity184. The second member181including a permanent magnet330as a magnetic field generator. The permanent magnet generates an attractive magnetic field for attracting said circular band movable finger187into frictional contact with said second member181to inhibit rotation between said first member183and said second member181. The magnetically actuated rotary motion control device preferably includes an adjustable magnetic field generating coil177, with the adjustable magnetic field generating coil177generating an adjustable coil magnetic field that cancels the permanent magnet attractive magnetic field to provide for retraction of the circular band movable finger187and inhibiting its frictional contact with said second member181. Permanent disk magnets330provide for having the attractive magnetic field, and therefore the damping force, applied most of the time with only short instances of turning the damping off. The permanent magnets are positioned and utilized in the rotary motion control damper so that the damper is in its on-state with the first member housing circular band movable finger187pressing against the second member181when no current is applied to the electromagnetic coil177such as shown inFIGS. 51A and 51D. As shown inFIG. 51Fthe electromagnetic coil177serves to cancel the field of the permanent magnets as current is applied to progressively turn the damper off.FIG. 51Dshows the magnetic field and magnetic flux due to the permanent magnets only.FIG. 51Eshows a magnetic flux due to the electromagnetic coil only.FIG. 51Fshows the net magnetic flux with the permanent magnet flux and the coil magnetic flux through the circular band movable finger187cancelled. Preferably the second member181is a circular stator with the stator having an outer circumference and the movable finger187is a circular band and encircles at least seventy percent of the second member stator outer circumference. In a preferred embodiment the circular band movable finger187includes a plurality of flex links509. As shown inFIG. 51, the second member181includes a steel core, a steel pole, a secondary gap non-magnetic spacer. The first member housing183includes a non-magnetic rotor cup and shaft, with the first member housing183and the second member181relatively rotatable about a center axis182with a sleeve bearing, with the assembly retained together with an outer large circumference wire retaining ring and an inner small circumference retaining ring. The permanent magnet330is preferably a plurality of permanent disk magnets positioned in a non-magnetic spacer disk, with plurality of spaced apart permanent magnets generating the attractive magnetic field for attracting said circular band movable finger187into frictional contact with said second member181. In an alternatively preferred embodiment the permanent magnet330is a permanent ring magnet which generates the attractive magnetic field for attracting said circular band movable finger187into frictional contact with said second member181. The permanent magnet330attracts the movable finger187into frictional contact to inhibit rotation between the first member housing183and the second member181. The coil177provides a means for canceling this attraction of the movable finger187to allow for rotation between the first member housing183and the second member181.

The present invention has been described with reference to exemplary embodiments. However, it will be readily apparent to those skilled in the art that it is possible to embody the invention in specific forms other than as described above without departing from the spirit of the invention. The exemplary embodiments are illustrative and should not be considered restrictive in any way. The scope of the invention is given by the appended claims, rather than the preceding description, and all variations and equivalents which fall within the range of the claims are intended to be embraced therein.