Abstract:
An alarm assembly is provided alerting the operator through one of a visual, audible, or tactile signal, the occurrence of a specified event. The alarm assembly includes a locking mechanism coupled to a substrate which has a natural frequency. The locking mechanism is maintained in a condition which inhibits the natural frequency of the substrate unless commanded to do so by an electronic circuit which includes sensors for monitoring one or more specific criterion. The locking mechanism is preferably a non-Newtonian flow fluid locking mechanism which uses a magneto-rheological fluid to dynamically adjust the locking strength of the locking mechanism as well as the natural frequency of the substrate based upon user inputs and dynamic events. The alarm assembly can be dynamically “tuned” in and out of the natural frequency of the substrate so the substrate vibrates, produces an audible noise, or generates a current upon the occurrence of a predetermined event. Sensors mounted on the substrate provide feedback via a logic system or computer to alter the stiffness of the locking system and increase or decrease the vibration to obtain or avoid the natural frequency.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of provisional patent application serial No. 60/208,181 filed May 31, 2000, the specification of which is incorporated herein by reference 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to alarm systems and particularly to a mechanism for actively alerting an operator of the occurrence of a specific condition requiring the attention of the operator. 
     2. Discussion of the Related Art 
     Substantially all mechanical devices, and in particular vehicles, have structures which have a “natural frequency.” The “natural frequency” of a component is the frequency at which a system oscillates in the absence of external forces; or, for a system with more than one degree of freedom, the frequency of one of the normal modes of vibration. Particular care is given during the designing of these components to avoid the “natural frequency.” The goal in most cases is to remove unwanted vibration to provide smooth and comfortable operation of the machine. 
     From an automobile manufacturer&#39;s viewpoint, the natural frequency of a component or assembly should be higher than a particular threshold, else the operator of the vehicle may detect some undesirable vibration, rattle, or “singing” during operation which is distracting, annoying, or disconcerting. Always, when an automobile manufacturer provides specifications to outside or third party vendors/suppliers, the natural frequency floor for the desired component/assembly is usually set out and is to be avoided. To the best of the inventor&#39;s knowledge, never has the natural frequency of a component been used to alert the operator of a condition. 
     SUMMARY OF THE INVENTION 
     The instant invention is an apparatus for interconnecting two objects together and permits the relative position of the two objects to be adjusted while the device is in a first state, and fixes the relative position of the two objects while the device is in a second state. The state of the device can be dynamically driven, and in particular, “tuned” to either avoid, or induce, the natural frequency of the coupled structures. 
     The apparatus embodying the invention includes a housing having at least one movable piston inside. Also inside the housing is a non-Newtonian flow fluid which passes through at least one passage within the housing. Adjacent the passage, or in close proximity thereto, is a device for selectively generating or neutralizing a magnetic field in and around the passage. The fluid within the housing flows through the passage when the magnetic field is weak or absent permitting the piston to move. When the magnetic field surrounding the passage reaches a predetermined strength, the fluid undergoes a change and ceases to flow, locking the relative position of the piston within the housing. If the strength of the field is increased, the effect of the field extends beyond that of the passage, and renders the device to be more rigid. 
     In one form of the invention, the invention is used to adjustably fix the relative position of the two interconnected components. The novel assembly includes an upper housing assembly coupled to a lower housing assembly in a manner to permit at least one of the upper and lower housing assemblies to articulate and telescope relative to the lower housing assembly. At least one non-Newtonian flow fluid-locking mechanism interconnects the upper housing assembly to the lower housing assembly for selectively fixing their relative positions. It is contemplated the apparatus includes a device for generating a magnetic field around at least a portion of the non-Newtonian flow fluid-locking mechanism for selectively activating and deactivating the fluid-locking mechanism. An electronic circuit and sensors are interconnected to the non-Newtonian flow fluid-locking device to dynamically adjust the strength of the magnetic field, thereby adjusting the rigidity of the locking mechanism. In the event the sensors detect the occurrence of a predetermined event, the strength of the magnetic field in the locking mechanism is changed to match the natural frequency of the component which produces one of an audible, tactile or visible signal to the operator. For example, in the event a sensor detects an object adjacent the left side of the vehicle, the circuit may be programmed to increase the magnetic field in the locking mechanism which controls the turn rate of the steering wheel, essentially providing tactile feed back to the operator which makes it more difficult to turn left and into the obstacle. 
     In yet another form of the invention, it is contemplated that the invention may be used to lock the rotation of the steering column, and act as a vehicle anti-theft system in the event the vehicle is broken into. The system would not deactivate until the key was inserted or some other system releases the device. Additionally, it is contemplated that the invention may be used to fix the relative position of seats, control pedals, and other objects within a vehicle, or match the natural frequency of those components such that they vibrate and provide a physical stimulus to the operator. 
     In still another form of the invention, an adjustable steering column is provided which is capable of tilting, telescoping, or both to the operators desired position. The locking system provided to fix the desired position of the steering column is dynamically adjusted or “tunable” in and out of the natural frequency of the steering column so the steering column vibrates upon the occurrence of a predetermined event. Sensors are mounted on the steering column to provide feedback via a logic system or computer to alter the stiffness of the locking system and increase or decrease the vibration of the column. For example, sensors could monitor the operator&#39;s eyes and determine when he/she has fallen asleep. If a condition is met, the locking mechanism is adjusted to permit the column to vibrate, and wake-up the operator. Once the condition is no longer satisfied, the system is tuned so the vibration stops and returns to normal operation. Similar systems could be used with seats, shift levers, control pedals, and the like. 
     These and other objects, advantages, purposes, and features of the invention will become more apparent from a study of the following description taken in conjunction with the drawing figures described below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a schematic diagram of one environment of application of the instant invention; 
     FIG. 2 is an enlarged elevation view of the invention shown in FIG. 1; 
     FIG. 3 is a bottom plan view of the invention shown in FIG. 2; 
     FIG. 4 is a schematic section view of one embodiment of the invention shown in FIGS. 2 and 3; 
     FIG. 5 is a schematic section view of an alternate embodiment of the invention shown in FIGS. 2 and 3; 
     FIG. 6 is a schematic section view of an embodiment of the invention in a telescoping assembly; 
     FIG. 7 is a schematic view of another application of the instant invention; 
     FIG. 8 is a schematic diagram illustrating a circuit used in combination with the instant invention to adjust the characteristics of the invention in response to specific input; 
     FIG. 9 is an oblique view of a tilting and telescoping steering column employing other embodiments of the instant invention; 
     FIG. 10 is an elevation section view of the invention shown in FIG. 9; 
     FIG. 11 is an oblique view of an embodiment of the instant invention used for translation of components; 
     FIG. 12 is a longitudinal section view of the invention shown in FIG. 11; and 
     FIG. 13 is a fragmentary section view of the invention shown in FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For purposes of the following description, the terms “upper,” “lower,” “right,” “left,” “rear,” “vertical,” “horizontal” and derivatives thereof shall relate to the invention as oriented in FIG.  2 . However, it is to be understood that the invention may assume various alternative orientations except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the specification and any appended claims. Specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     Although the instant invention has application to substantially any situation where it is desirable to prompt an operator to the occurrence of an event, the following description is made with specific reference to applications in vehicles, and more to a steering column where it is common to provide tilt and/or telescoping movement of one component (the steering wheel) relative to another (the steering column). 
     Referring to drawing FIGS. 1 through 3, a steering column assembly  10  is shown mounted in a vehicle  12  such as a truck, wherein a steering wheel assembly  14  is provided at one end, and the opposite end is interconnected to a steering gear box  16  for steering the front wheels of the vehicle  12 . The upper portion of the steering column assembly  10  (FIG. 2) includes a lower housing assembly  20  interconnected to the upper housing assembly  22  in a manner to permit articulation or tilting of the upper housing assembly  22  relative to the lower housing assembly  20 , translation or telescoping motion of the upper housing assembly  22  relative to the lower housing assembly  20 , or both. In the embodiment shown, upper housing assembly  22  is pivotally coupled at its lower end  24  by pins  26  to arms  28  of a yoke  30  attached to the upper end  32  of the lower housing assembly  20 . The pivot axis defined by pins  26  is preferably substantially horizontal to provide for a limited arc of rotation in a vertical plane. 
     The upper and lower housing assemblies  22  and  20 , respectively, of the steering column assembly  10  enclose a series of interconnected rotatable shafts (not shown) connected at one end to the steering wheel assembly  14  and at an opposite end to a steering gear box  16 . A universal joint or similar coupling interconnects the shafts to permit tilt movement of the upper housing assembly  22  relative to lower housing assembly  20 . A telescoping shaft may be attached to the upper shaft to permit longitudinal adjustment of the steering column assembly  10 . 
     Lower housing assembly  20  generally includes a tubular member  36  preferably made from steel with a collar  38  securely attached to the upper end  32  by weldment or similar coupling. Arms  28  of a yoke  30  diverge and extend outwardly from a longitudinal axis of the lower housing assembly  20  to a distance sufficient to receive the upper housing assembly  22  there between. Generally arcuate openings  40  are provided at the distal ends of each arm  28  to receive a guide pin  42  attached to the upper housing assembly  22 . The guide pins  42  interact with the arcuate openings  40  to define the tilt limits of the upper housing assembly  22  with respect to the lower housing assembly  20 . In the illustrated embodiment, arms  28  of the yoke  36  are stamped or otherwise formed from steel bar stock and have the lower ends welded to the collar  38  to produce a rigid fork attachment at the upper end  32  of the lower housing assembly  20 . Additional information and alternatives on the nature of the pivotal coupling between the upper housing assembly  22  and the lower housing assembly  20  are disclosed in U.S. Pat. No. 5,899,487, granted May 11, 1999. 
     Referring to the embodiment shown in FIGS. 2 and 3, the lower and upper housing assemblies  20  and  22 , respectively, are interconnected by locking mechanism  50 , preferably at points vertically offset from the horizontal mid-line of the steering column assembly  10 , and most preferably at a point farthest from the pivot access defined by pins  26 . The upper housing assembly  22  has at least one, and preferably two flanges  52  extending generally perpendicular at a point proximate the lower end  24  to define a bracket. A similar structure extends perpendicular from tubular member  36  or from collar  38  generally identified by reference numeral  54 . Attached to bracket  54  by a pin  56 , and centered between bushings  58 , is one end of the locking mechanism  50 . The opposite end of the locking mechanism  50  is pivotally coupled to bracket  54 . 
     FIG. 4 schematically illustrates an embodiment of a locking mechanism  50  used in combination with the instant invention. Locking mechanism  50  is preferably a fluid-locking mechanism having a housing  66 , preferably in the shape of a right circular cylinder closed at end  78 , and having an opening  82  at an opposite end  80  of sufficient diameter to permit the passage of shaft  62  there through. The central or intermediate portion  84  of housing  66  has a reduced intermediate portion (RIP) to create a constriction generally uniformly around shaft  62 . The specific dimension of RIP  84  will vary depending upon the diameter of shaft  62 . RIP  84  essentially divides the housing  66  into two chambers  89  and  90 , each containing a respective piston  68  and  70 . Pistons  68  and  70  each have a diameter substantially equal to the interior diameter of the respective chambers. O-rings or similar acting seals  91  may extend around the circumference of each piston  68  and  70  to form a tight seal with the interior wall  92  of the chambers  89  and  90 . A specific volume is defined between the interior surfaces  94  and  96  of the pistons  68  and  70 , respectively, and the interior wall  92 . Disposed within this volume is a non-Newtonian flow fluid  97  such as that disclosed in any one of U.S. Pat. Nos. 5,277,281; 5,284,330; 5,492,312; 5,816,372; and 5,711,746, all assigned to the Lord Corporation. The portions of the respective chambers outboard of the pistons  68  and  70  may be filled with ambient air passing through holes  98  extending through the walls of ends  78  and  80 . 
     Disposed around housing  66  adjacent RIP  84  is a device for generating a magnetic field within the interior of the housing  66  and particularly across the inside diameter of RIP  84 . In one embodiment, the device  84  includes a electromagnet coil  85  operably connected by conductors  86  to a power supply  87 . The flow of current through conductors  86  and electromagnet coil  85  is controlled by a switch  88  mounted in either the steering wheel, or a module mounted in or near the column and possibly activated by a lever. The actual mounting method or location is not important so long as it is reasonably accessible by the operator. In this embodiment, depression of switch  88  interrupts the power to electromagnet coil  85 . Alternatively, the device surrounding RIP  84  may include a split annular magnet. Each half of the magnet would be coupled to a mechanical linkage which would move each magnet toward or away from RIP  84  to engage and disengage the mechanism. In yet another form, permanent magnets may be mounted around RIP  84  of sufficient shape and size to produce a magnetic field or flux across the inside of RIP  84 . Arranged around the outside of the magnets may be a wire coil similar to  85  coupled to a circuit by conductors. The circuit may be designed such that when activated, the electromagnetic force produced by the electromagnet coil  85  would counter the magnetic field produced by the magnets, canceling each other to produce a field force region across RIP  84 , and allowing the fluid to move between the chambers. 
     All forms of the device are preferably operably connected to a crash sensor to interrupt the supply of power, disengage or neutralize the magnets to unlock the mechanism. In this manner, a substantial portion of the impact could be absorbed by the mechanism rather than by the occupant. 
     In operation, a bias on conductors  86  produced by the power supply  87  causes electromagnet coil  85  to produce a magnetic field across the non-Newtonian flow fluid in chambers  89  and  90  and most particularly across the interior of the restriction produced by RIP  84  and the intermediate portion of shaft  62 . The field causes the fluid within that region to alter state sufficient to prevent the fluid to pass through the RIP  84 , and locks pistons  68  and  70  in place. This magneto-rheological condition firmly fixes the relative position of the shaft  62  with respect to the housing  66  which in turn fixes the relative position of the upper housing assembly  22  with respect to the lower housing assembly  20 . In order to change the relative position of the upper housing assembly  22 , the operator depresses switch  88 , a lever, or other input device to interrupt the field across RIP  84  and allowing the fluid to change state and flow through the passages defined between RIP  84  and shaft  62 . By permitting the pistons  68  and  70  to translate within the respective chambers  89  and  90 , the operator can then change the relative position of the upper housing assembly  22  with respect to the lower housing assembly  20 . Releasing the switch  88  restores the magnetic field which then in turn prevents the flow of fluid between the respective chambers  89  and  90 . In the case of an electromagnet, the force necessary to change the position of the pistons  68  and  70  may be varied—in essence fine tuning the locking mechanism  50 . Resistance could be varied by changing the volume or size of the passage through which the fluid migrates as the piston moves. Other available modifications include changing the diameter of the pistons  68  and  70 , or changing the diameter of the piston passing through the RIP  84 . A change in one or more of these elements produces a change in the amount of force necessary to move the piston and attached shaft  62 . 
     FIG. 5 illustrates an alternate embodiment of the locking mechanism  50  using a single piston design  150 . The single piston design  150  includes a shaft  162  having a connector  160  at one end which is configured to be coupled to brackets  52  or  54  using the same type of pin  56  and bushing  58  arrangements described earlier. The opposite end of the shaft  164  terminates in piston  168  which may include a coil of wire to form an electromagnet coil  185 . The leads from the electromagnet coil  185  may extend up through a central hollow core  163  of the shaft  162  and exit a port  165  proximate the connector  160 . There the conductors  186  are interconnected to a switch  189  and a power supply  187  which selectively energizes the electromagnet coil  185 . 
     Piston  168  and a portion of the shaft  162  are disposed within a chamber  188  defined by housing  166 . The external diameter of the piston  168  may vary in dimension from a size substantially equal to the inside diameter of the chamber  188  or be of a lesser size to control the dimension or space between the perimeter of the piston  168  and the interior wall  192  (hereafter the “perimeter volume”) which provides the same function as RIP  84  above. Chamber  188  to the housing  166  is filled with the non-Newtonian flow fluid. The entire housing  166  is preferably sealed including the passage through which shaft  162  extends in order to prevent the fluid from leaking. Although single seals are shown in the drawing figure, it is anticipated that a number of redundant seals and bushings may be used to retain the fluid within the chamber  188  and prevent a robust seal. 
     With the two connectors  160  and  174  pivotally secured to the respective brackets  52  and  54 , and with a bias supplied over conductors  186  to energize electromagnet coil  185 , the non-Newtonian fluid is unable to pass between the perimeter of the piston  168  and the interior wall  192  creating a condition where the piston  168  and shaft  162  are rigidly secured with respect to the housing  166 . Upon the operator&#39;s selection and depression of switch  188  and interruption of the power along conductors  186 , the fluid state changes and passes about the periphery of the-piston  168  to permit a change of position of the column. Although not shown, it is anticipated that piston  168  may substantially extend across and fill the interior of the housing  166 . In order to permit the passage of the fluid, ports may extend through the piston which could be metered using jets to adjust the resistance. 
     In both of the embodiments described above, the locking device is functioning in a Coulomb or Bingham lock, i.e., this configuration approximates an ideal lock in which the force generated is independent of piston velocity and large forces can be generated with low or zero velocity. This independence improves controllability of the lock making the force a function of the magnetic field strength, which is a function of the current flow in the circuit or the field strength produced by an adjacent magnet. In basic terms, the flow of magnetic flux is dependent on several factors in the flow path. The minimum lateral cross-sectional area of the piston ( 68 ,  70  or  168 ) within the windings of the electromagnet coil  185 ; the minimum lateral cross-sectional area of magnetically permeable material finding a return path from magnetic flux; and a surface area of the magnetic pull of the piston, all having values as defined in U.S. Pat. No. 5,284,330. 
     The instant invention may also be used to reduce the deceleration impact of the operator with the steering column in the event of a crash. This is accomplished by interrupting the conductors  186  using a switch operably connected to a crash sensor in the vehicle. At the specified threshold, the sensor interrupts the bias in the conductors  186 , thus deactivating the electromagnet coil  185  and allowing the steering column to be repositioned. In a preferred embodiment, a pyrotechnic actuator may be attached to the bracket  52  on the lower side of upper housing assembly  22  so in the event of a crash, the locking mechanism  50  is de-energized and the pyrotechnic pre-positioning system pulls the steering column downward and away from the operator so that the air bag within the steering wheel deploys to more fully absorb any impact. 
     In reference to FIG. 6, a portion of a telescoping steering column assembly  300  is shown comprising a shaft  302  configured at one end  304  to attach to the steering wheel. The opposite end of the shaft terminates in a piston  306  having a diameter slightly less than the diameter of the shaft  302 . The piston  306  is coupled to shaft  302  by a neck  308 . Piston  306  and the necked-down portion  308  of shaft  302  are received in a cylinder  310  closed by seal  312  to define a fixed volume  314  similar to that defined by the housing  166  and piston  168  in the embodiment shown in FIG.  5 . The volume  314  is filled with the non-Newtonian flow fluid  316  to completely envelope the piston  306  and the portion of the shaft  302  extending through the seal  312 . The cylinder  310  may be formed in one end of shaft  318  which forms the remaining portion of the shaft in the upper or lower housing. To prevent rotation of shaft  302  relative to shaft  318 , splines may be provided along the upper interior or end of shaft  318  and above neck  308 . The splines would permit axial translation, but fix the two shafts rotationally. The respective shafts  310  and  302  are preferably journaled by bearings well known in steering technology. 
     In this configuration, it is anticipated that an electromagnetic coil  320  may be disposed on the exterior portion of the upper end of the shaft  318  to create the magnetic flux in the non-Newtonian flow fluid  316  disposed within the chamber  314  sufficient to prohibit the fluid from passing through or around the perimeter of the piston  306 . In the alternative, it is contemplated that the shaft  302  may be hollow to provide a passage for conductors to a coil formed in the interior of the piston  306  to create the necessary magnetic flux. The circuit used may be similar to that described above and could be used in combination with the crash sensors so the relative telescoping position of the shaft  302  may be changed with respect to the shaft  318 . 
     In yet another embodiment of the invention, the locking mechanism  50  may be used to control the relative height, recline angle of a seat back  408  and seat base  400 ; as well as the horizontal position of the seat with respect to the steering wheel. FIG. 7 schematically illustrates these various other applications. For example, the seat base  400  may be supported above a track  402  and mounted to a carriage  404  by a plurality of the locking devices generally identified as  406 . In addition, the angular position of the seat back  408  may be controlled by a locking device  410  interconnected to the seat back  408  and the seat base  400 . Lastly, horizontal travel of the carriage may be controlled by a locking device  412  mounted at one end to the floor or frame of the vehicle and at the opposite end to the carriage  404 . Just as in the previous embodiments, one or all of these locking devices  406 ,  410 , and  412  may be used to set the relative position of the seat components. In addition, pyrotechnic propositioning systems may be integrated to change the position of the seat in a crash. 
     It was briefly mentioned above that the instant invention may be used to reduce the impact of the occupant with the steering wheel in the event of a crash. FIG. 8 shows, in schematic form, one assembly for achieving that function. In this embodiment, the locking device  550  includes a locking mechanism  552  operably coupled by conductors  554  to a controller  556  (CLR) which, in turn, is operably coupled to a ground  557  and a power source  555  for the circuit. Controller  556  has a plurality of inputs, including, but not limited to, a tilt adjustment switch  558 , a weight sensor  560 , a height sensor  562 , an ignition sensor  564 , and a crash sensor  566 . Additional sensors could include accelerometers for indicating the direction of an impact and a sensor for measuring the speed of the vehicle. 
     Controller  556  may be a microchip, programmable logic controller, micro computer or other processor capable of utilizing data provided by the various sensors to determine the necessary current applied over conductors  554  to control the strength of the magnetic field produced by locking mechanism  552 . That is to say the controller  556  would dynamically change the locking characteristics in accordance with the various inputs so any impact by the operator is absorbed by the column rather than the occupant. In addition, this same circuitry could include a memory circuit for recalling particulars about a particular incident, for example, the system may be able to indicate whether the operator was traveling a certain speed, and direction, and whether the seat belt was in use. The system could also record the impact direction and force. All of this information would be useful in determining the facts surrounding an accident. This same controller  556  may also include information stored by the operator on the preferred position of the column, the control pedals, the seat position, and the like. 
     FIG. 9 illustrates a steering column assembly  600  incorporating in the instant invention a tilting column, as well as a telescoping column. The steering column assembly  600  includes a lower housing assembly  602  which is intended to be secured by flanges  604  to a section  606  of the steering column which, in turn, may be attached to the fire wall, dash assembly, or other rigid structure in the vehicle. The interior of the lower housing assembly  602  is designed to receive a telescoping inner housing assembly or shuttle  608 . The inner housing assembly or shuttle  608  is configured to slide within the lower housing assembly  602  between an extended or retracted position along an axis parallel to the longitudinal axis of the lower housing assembly  602 . Inner housing assembly or shuttle  608  may be of a particular shape received within a correspondingly shaped passage formed in the interior of the lower housing assembly  602  with bearing surfaces provided to allow a smooth translation of the inner housing assembly or shuttle  608  with respect to the lower housing assembly  602 . An end of the inner housing assembly or shuttle  608  extending from the lower housing assembly  602  may be fitted with a pair of brackets  612 , and each disposed on opposite sides of the inner housing assembly or shuttle  608 . Each bracket  612  may be generally L-shaped or dog-legged such that one portion of the leg  614  is securely attached to the end of the inner housing assembly or shuttle  608 , and the other portion or leg  616  extends at an angle to leg  614  and generally tangential to the exterior of the lower housing assembly  602 . 
     Pivotally coupled between the ends of legs  614  may be the lower end  618  of the upper housing assembly  620 . The coupling could permit articulating motion of the upper housing assembly  620  with respect to the lower housing assembly  602  about an axis generally horizontal and defined by bolts  622 . For specifics on the coupling between the bolts  622  and the attached components, the reader is referred to U.S. Pat. No. 5,899,497 issued on May 4, 1999. In the embodiment shown in FIG. 9, the upper housing assembly  620  also includes a bracket  624  of a predetermined dimension having a plurality of cutouts  626  to receive various gauges. Also extending from the upper housing assembly  620  proximate the lower end  618  is a buttressed flange  628 . Buttressed flange  628  is interconnected to the lower legs  616  of each bracket  612  by a fluid locking mechanism identified by the reference numeral  630 . A more detailed illustration of the fluid locking mechanism  630  is made with respect to FIG.  10 . 
     Fluid locking mechanism  630  includes a housing  632  having at least one piston  634  slidably disposed therein to define at least two chambers  636  and  638 . Extending from the piston  634  is a piston shaft  640  which extends from the housing  632  and terminates in a clevis  642 . The clevis  642  may be pivotally attached to the buttressed flange  628  by one or more bolts  644 (FIG.  9 ). Housing  632  is also similarly pivotally attached to the ends of the legs  616  by bolts  646  extending through the legs  616  and into mounting plates  648  formed on the exterior of the housing  632 . With the fluid locking mechanism  630  in the unlocked state, the upper housing assembly  620  is permitted to tilt or pivot about the coupling point defined by bolt  622 . The pivotal couplings provided by bolts  644  and  646  permit the angular orientation of the fluid locking mechanism  630  to vary as the upper housing assembly  620  is moved about the pivot point. 
     Referring again to FIG. 10, housing  632  is preferably cylindrical and opened at one end  650  to permit the insertion of various components therein. A piston shaft  640  extends through a sealed opening  652  defined in the opposite end  654  of the housing  632 . Concentrically disposed in the interior wall  655  of the housing  632 , and spaced inwardly away from the interior wall  655  of the housing  632  is an inner sleeve  656  which has an inside diameter approximately equal to the outer diameter of the piston  634 . The inner sleeve  656  is retained in position by one or more shoulders at each end of the housing  632  or from the end cap  658  received within the end  650  of the housing  632 . The end cap  658  is sealed in position using C-clips and seals conventional in the art. The interior of the housing  632 , the chambers  636  and  638 , and the volume between the inner sleeve  656  and the interior wall  655  of the housing  632  are filled with the non-Newtonian flow fluid  660 . The non-Newtonian flow fluid  660  in chamber  636  is permitted to flow into chamber  638  through space  662  located at the ends of the inner sleeve  656 , and through the peripheral volume between the inner sleeve  656  and the interior wall  655 . The flow of fluid from one chamber to the other may be controlled in a number of ways. Primarily the rate of fluid exchange is determined by the size of the smallest opening, defined by either the space  662  or the cross-section of the peripheral passage. The locking power of the mechanism is controlled in substantial respect by the intensity of the magnetic field or flux across those small areas. In the instant invention, a coil is provided which generates an electromagnetic field upon the application of a particular current. Alternatively, permanent magnets may be used, the field of which may be neutralized by the application of electromagnetic field. Although the electromagnetic field is described as occurring at one end of the inner sleeve  656 , the electromagnetic force or field may be produced at other areas of the locking mechanism  630  to change the flow state of the non-Newtonian flow fluid  660 . For clarity, the type of fluid used in the fluid locking mechanism is substantially similar to the fluid described above, and available from the Lord Corporation. By varying the magnetic flux, the flow characteristic of the non-Newtonian flow fluid  660  is changed. In one state, the non-Newtonian flow fluid  660  is unable to pass through the small space  662 , essentially trapping the remainder of the non-Newtonian flow fluid  660  within the respective chambers, and fixing the relative position of the piston  634  within the housing  632 . Thus, to change the relative tilt angle of the upper housing assembly  620  with respect to the lower housing assembly  602 , the operator simply removes the electromagnetic field present within the fluid locking mechanism  630 . 
     FIGS. 11 and 12 illustrate another embodiment of the fluid locking mechanism, particularly as it applies to fixing the translation, or telescoping position of two components—in this case, the telescoping steering column. FIG. 11 schematically illustrates the lower housing assembly  602  in relation to the section  606  and the interconnecting flanges  604 . Extending longitudinally through the lower housing assembly  602  is an inner tubular member identified by reference numeral  670  which is configured to translate longitudinally with respect to the lower housing assembly  602 . For the purposes of illustration, inner tubular member  670  may be equivalent to the inner housing assembly or shuttle  608 . Extending concentrically through the inner tubular member  670  may be a telescoping shaft  672  passing through bearing  674  and extending a predetermined distance into the inner tubular member  670 . In a preferred embodiment, the portion of telescoping shaft  672  extending within the inner tubular member  670  is splined longitudinally. Telescopically received over the splined end is a second shaft  676  having a female coupling complimentary in shape to the splined end of the telescoping shaft  672 . Shaft  676  is intended to extend through the opposite end of the inner tubular member  670  and may be supported by a bearing within end  678  or elsewhere along its length. End  678  of the inner tubular member  670  may be also configured to be interconnected to the brackets such as  612  described above by an adapter member not shown received over the end  678 . The attachment member for interconnecting the end  678  of the inner tubular member  670  to the brackets  612  may be of sufficient diameter such that the brackets  612  are located generally parallel and adjacent the exterior of the lower housing assembly  602 . 
     It is contemplated that lower housing assembly  602  may be generally tubular, and substantially closed at one end  678  by an end wall  680 . The opposite end  682  may be closed by a removable end cap  684 . Both the end wall  680  and the removable end cap  684  may have openings or passages defined therein to receive the inner tubular member  670  there through. Conventional seals and bushings may be provided such as  690  and  688  to provide a fluid-tight seal around the inner tubular member  670 . 
     Intermediate on inner tubular member  670  may be an electromagnetic coil or magnet  692  seated in an armature  694  which is retained generally in place by snap rings  696  seated in groves at each end of the armature  694 . In the case of a wire coil mounted on the armature  694 , a hole is provided in the armature  694  to allow the wire leads to extend there through and through the inner tubular member  670  for connection to the circuit. To prevent the armature  694  from rotating around the inner tubular member  670 , a pin may be provided, extending from the inner tubular member  670 , and received in a slot formed in the underside of the armature  694  to fix the rotation of the armature  694  relative to the inner tubular member  670 . A similar arrangement may be used, if desired, to fix the relative rotational position of the inner tubular member  670  with respect to the lower housing assembly  602 . Alternatively, mechanisms exterior of inner tubular member  670  may prevent rotation. For example, it is contemplated that each bracket  612  may have a slotted structure such as suggested by reference numeral  695  (FIG. 9) which rides over and is engaged by a cam such as suggested by reference numeral  697  (FIG.  11 ). 
     Disposed within the interior of the lower housing assembly  602  may be an inner sleeve  698  which has an outside diameter approximately equal to the inside diameter of the lower housing assembly  602  and is positioned between the end wall  680  and the removable end cap  684 . The inner diameter of the inner sleeve  698  may vary, but in no event is it less than the outside diameter of the armature  694  and that of the electromagnetic coil or magnet  692 . In a preferred embodiment, the inside diameter of the inner sleeve  698  is such that a small gap approximately on the order of 1 to 2 millimeters or less is present between the outside diameter of the armature  694  and the inside diameter of the inner sleeve  698 . In this fashion, a narrow passage exists between chamber  700  and chamber  702 . The two chambers and the narrow passage interconnecting the two chambers is filled with the non-Newtonian fluid  704  similar to that described above. 
     When an electromagnetic field exists across the gap between the chambers  700  and  702 , the non-Newtonian fluid  704  within that gap, and to a certain degree in each chamber, changes states from a conventional fluid to a more viscous material which is unable to flow through the gap. The particular state of fluid prevents the exchange of fluid between the respective chambers and thus locks the armature  694 , and the inner tubular member  670  in position with respect to the lower housing assembly  602 . When the electromagnetic field is neutralized, or removed, the non-Newtonian fluid  704  reverts to its natural state, and permitted to flow across the gap from one chamber to the other when inner tubular member  670  is translated. To the extent that shaft  676  also moves with respect to the inner tubular member  670 , the spline ends of shafts  676  and  672  permit the relative telescopic adjustment. 
     In each of the embodiments described above, it is preferred that a nonferrous material be used for the various components which are substantially adjacent or in close proximity to the magnetic/electromagnetic components. The use of nonferrous materials prevents the polarization or magnetization of those components which would result in the continued presence of a magnetic field, thus possibly impacting the function of the locking mechanism. Acceptable materials would include bronze, aluminum, and polymeric materials. 
     According to another embodiment of the instant invention used to alert an operator to a safety condition, a steering column assembly  630  such as shown in FIG. 10 is provided which includes a lower housing assembly  602  and an upper housing assembly  620 , both interconnected in a manner such that the upper housing assembly  620  is movable with respect to the lower housing assembly  602  in a tilting fashion, telescoping fashion, or both as described generally above. More particularly, it is envisioned that the upper housing assembly  620  is pivotally coupled at its lower end  618  to the upper end of the lower housing assembly  602 . Alternatively, the upper housing assembly  620  may be attached to an inner housing assembly or shuttle  608  which is slidably received within the lower housing assembly  602  to permit telescopic movement of the upper housing assembly  620 . To fix the relative tilt position of the upper housing assembly  620  with respect to the lower housing assembly  602  may be a fluid locking mechanism  630  such as available from the Lord Corporation and using the magneto-rheological properties of a fluid within a linear actuator to lock interconnected components described generally above. A separate and independent fluid-locking mechanism such as described in FIGS. 12 and 13 may be provided to control the telescoping action of the column. 
     The fluid locking mechanisms  550  and  630  are interconnected by wire leads ( 554  on FIG.  8  and marked in FIG. 12) to a logic circuit such as a controller  556  (FIG. 8) which controls the amount of current to lock and unlock the mechanisms. Also connected to the controller  556  by wire (copper or optical) leads are sensors  558 ,  560 ,  562 ,  564 ,  566  and  559  such as proximity sensors, accelerometers, transducers, piezoelectric sensors and the like. In the embodiment shown, the sensors  559 ,  561 , and  563  are accelerometers and/or transducers which are mounted to the steering column in at least one orientation, and preferably along orthogonal axes. The sensors are intended to provide dynamic feedback to the controller  556  so the locking force of the mechanism can be adjusted to match the natural frequency of the assembly upon the happening of a predetermined event to alert the operator to a specific condition. Also connected to the controller  556  are additional sensors generally indicated by numerals  565  and  567  which are intended to detect a range of conditions, the occurrence of which triggers the alarm to alert the operator. 
     It is anticipated that the sensors  565  and  567  may be provided to measure certain conditions, such as the proximity of the vehicle to an obstacle, or the operator&#39;s state of awareness. For example, the sensors may be provided to monitor the operator&#39;s eye movement as shown by sensor  565 . Should a low threshold be detected (low eye movement), the controller  556  may assume the operator has fallen asleep or is drowsy and adjust the current to the locking mechanism  552  such that the connection between the two vehicle components  602 ,  620  matches the natural frequency, waking the operator. In addition, the controller  556  may be coupled to distance sensors such as  567  (DIST. SENS.) which monitor the proximity of the vehicle to other objects or reference points along a road which results in a triggering of the “natural frequency” alarm. Alternatively, the device under control may also produce an audible signal when set to the natural frequency. Such audible signals could also be used to alert the operator to the occurrence of a condition. For example, the device may be attached to a diaphragm or transducer or other material which resonates at a particular audible frequency to alert the operator. For visual signals the locking device may be used to control the natural frequency of a piezoelectric transducer such that when the frequency is matched, an electrical current is generated to illuminate an indicator or produce an audible signal. 
     In addition to using the natural frequency of a vehicle component or assembly, such as the steering column to alert the operator, the instant invention can be used in conjunction with a component or assembly to avoid the natural frequency. The fluid locking mechanism  630  and associated circuitry could be implemented in a manner to couple the components such that the natural frequency is avoided, thus producing the smooth and desired operation of the vehicle. The implementation of this assembly may also result in a reduction of the front-end engineering cost associated with avoiding the natural frequency problem associated with certain parts/assemblies. 
     The electrical circuit anticipated to be used to carry out the instant invention can assume a wide array of configurations. Once one of ordinary skill of the art in electrical engineering, once in possession of the goals of the instant invention, could produce a circuit which could receive the different outputs from the various sensors and compare them to predetermined thresholds. This same individual, knowing the natural frequency of the component coupled to the magneto-rheological device, and how to adjust the magneto-rheological device to either avoid or achieve the natural frequency, could produce a circuit wherein the natural frequency is avoided unless certain criterion are indicated by the sensors. 
     Various changes, alternatives and modifications will become apparent to those of ordinary skill in the art following a reading of the foregoing description. For example, although electromagnets have been described, it will appreciate that permanent magnets may be utilized to provide some or all of the magnetic field. The intensity or strength of the magnetic flux through the fluid may be changed by altering the distance of the magnet from the RIP or cylinder. It is further contemplated that the instant invention may be adapted for use in controlling the rotation of a steering wheel shaft, or similar structure using a device described in U.S. Pat. Nos. 5,492,312; 5,711,746; and 5,816,372 issued in the name of the Lord Corporation. With the advent of electrical steering systems, it is also contemplated that these devices could be used to provide adjustable tactile feedback through the steering wheel to provide the operator with a range of steering control settings. In yet another application, the locking mechanism may be operably coupled to a force sensor located in the steering wheel of the vehicle via a computer. The sensor would generate a signal which would be processed by the computer to vary the flux in the locking mechanism during an accident wherein the locking mechanism would accommodate and absorb some of the energy resulting from the impact of the occupant with the steering wheel. Lastly, a different implementation of the locking system would include adjusting the relative position of structures such as seats and structures such as instrument panels and the like. It is intended that all such changes, alternatives and modifications have come within the scope of the foregoing description be considered as part of the present invention. 
     The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.