Abstract:
A re-locatable operator station device designed to be used to control walk-behind or stationary machinery and to be repositioned by an operator while maintaining a constant orientation with respect to the machinery. This means that the X and Y axis of the operating station remains the same as the X and Y axis of the vehicle. Such re-locatable operator station is being suitable for use on machinery such as pallet trucks, long load transporters, aircraft engine handling devices, scissors lifts, and other industrial machinery, especially omni or multi-directional machinery or vehicles, as well as with fixed machines in applications places where the operator cannot or does not remain in a single location or is better served at another location.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS  
       [0001]     None.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates generally to the field of operator controls for remotely controlled vehicles, and more particularly to a controller designed to be used to control walk-behind, stationary, or ride-on machinery such as pallet trucks, long load transporters, aircraft engine handling devices, scissors lifts, especially omni or multi-directional vehicles or machinery and other industrial machinery.  
         [0003]     Walk-behind, remote controlled, and other machines have used various means to convey operator commands to the machine. Some machines have been constructed with either tethered or wireless controls. A tethered control will generally consist of an enclosure to be held by or strapped to an operator. The control enclosure will typically have a “dead man” or enable switch or button, a joy stick or other velocity command input device, mission hardware control input devices such as buttons, toggle switches, one, two, or three axis joy sticks, six-axis force input devices such as a “space ball” or other devices to control embarked machinery and systems, and perhaps an emergency stop button.  
         [0004]     Tethered systems are always at risk of the vehicle running over the tether or fouling it on other obstructions. The tether may become entangled in one of the wheels or other moving component and broken, necessitating the machine to be taken out of service.  
         [0005]     Tethered systems have the disadvantage that the tethers are relatively delicate and can become damaged by personnel stepping on them, or chafed from being dragged on the ground. Strain relief is another issue, and continual flexing can cause the interconnecting wiring to fatigue and break, potentially resulting in loss of control.  
         [0006]     Wireless control systems have also been developed where the operator is equipped with a command input device that is held by the operator while in use. The wireless command input device can also be suspended from a belt or suspenders. Industrial wireless systems can function in most industrial environments, but are not able to function in some military electromagnetic environments, in particular where radars or other high power electromagnetic radiating devices are in use. Wireless systems also emit radio frequency (RF) energy that can interfere with weapons and communication systems in a military environment.  
         [0007]     Both tethered and wireless systems have the disadvantage of not conveying the machine&#39;s motion directly to the operator via tactile feedback. This is most detrimental when making small, precise motions in constricted environments where an error could damage delicate equipment or injure nearby personnel. An operator that has tactile feel for the machine&#39;s motion will be less likely to cause damage in such situations.  
         [0008]     Machines controlled via tethered or wireless links can be turned in a direction wherein the front of the machine differs in orientation from the face of the operator, and in such an orientation the operator may become confused and inadvertently command the machine in a direction different from that desired, causing frustration or accidents. This refers, more specifically, to the X and Y axis of the operating station remaining the same as the X and Y axis of the vehicle. In emergency situations this potential for operator confusion or disorientation relative to the front of the machine and hence the direction of travel can be particularly dangerous, since an operator&#39;s initial instinctive reaction may be different than that needed to avoid a collision or bystander.  
         [0009]     Many industrial and military machines have been equipped with a rigid operator interface. In some cases, as in a commercial powered pallet handler device, the operator interface may take the form of a “T” shaped handle with finger operated paddle controls. The paddle controls may be used to convey velocity commands and or lift and tilt or other commands as appropriate.  
         [0010]     Sometimes such operator interfaces are arranged to rotate with the steered wheels, and in some cases, the operator&#39;s physical input is used as the steering actuation force. For example, the US Navy MHU191 weapons handler dolly is equipped with an extendable handle that is linked to the front wheels. An operator will rotate the handle about the front of the vehicle to the desired direction to turn and then either push or pull on the handle or other part of the payload or dolly to move it in that direction. Centering the MHU191 dolly handle will cause the MHU191 dolly to move in a straight path when pushed. In another example, a electrically powered pallet jack can have a “T” shaped handle that is connected to powered wheels which are further arranged to support one end of the machine. In order to change the machine&#39;s direction of travel, the operator manually rotates the “T” handle about the powered wheels, thereby orienting them into the desired direction.  
         [0011]     The aforementioned arrangements have the disadvantage that the operator&#39;s juxtaposition to the machine is fixed. That is, the operator must be located centrally behind the machine while traveling a straight path, or to the side of the machine facing the inside of the turn while traveling on a curved path. The operator is not able to, for instance, view the side of the machine facing the outside of a turn, or to walk from a vantage point far to one side of the machine while traveling in a straight path.  
         [0012]     Therefore, there exists a need for an operator interface that provides tactile feedback to the operator. There also exists a need for a walk behind machine operator interface that permits the operator to walk from different vantage points while the machine is in motion and under control. There also is a need for an operator interface that provides tactile feedback and that can be relocated all while maintaining a constant rotational geometry about the vertical axis.  
       SUMMARY OF THE INVENTION  
       [0013]     The invention provides a re-locatable or moveable operator station device designed to be used to control walk-behind or stationary machinery and to be able to be repositioned by an operator while maintaining a constant orientation with respect to the front or face of the machinery. This refers to the X and Y axis of the operating station remaining the same as the X and Y axis of the vehicle.  
         [0014]     The re-locatable operator station is suitable for use on machinery such as pallet trucks, long or short load transporters, military munitions handlers, aircraft engine handling devices, scissors lifts, and other industrial machinery, as well as with fixed machines in applications where the operator cannot remain in a single location or is better served by being permitted to relocate without losing orientation with respect to the front or face of the machine. This is especially prevalent with the use of omni or multi-directional vehicles or machinery. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1A  depicts a vehicle equipped with an embodiment of the present invention.  
         [0016]      FIG. 1B  is a detail view of a portion of the vehicle depicted in  FIG. 1A .  
         [0017]      FIG. 2  shows a bird&#39;s eye view of a vehicle equipped with an embodiment of the present invention depicting the range of operator station locations.  
         [0018]      FIGS. 3A and 3B  show a detail of a first embodiment of the invention.  
         [0019]      FIGS. 4A and 4B  show details of a vertical linkage.  
         [0020]      FIG. 5 . shows a detail of an operator interface.  
         [0021]      FIGS. 6A and 6B  show a detail of a second embodiment of the present invention.  
         [0022]      FIGS. 7A and 7B  show a detail of a third embodiment of the present invention.  
         [0023]      FIG. 8  shows an embodiment of the invention used with an aircraft engine handling machine.  
         [0024]      FIG. 9  depicts a scissors lift equipped with an embodiment of the invention.  
         [0025]      FIGS. 10A and 10B  depict a long load transporter equipped with an embodiment of the invention.  
         [0026]      FIG. 11  depicts a long load transporter equipped with an embodiment of the invention negotiating an overhead obstruction.  
         [0027]      FIG. 12  depicts a ride on machine equipped with an embodiment of the invention.  
         [0028]      FIG. 13  depicts a tracked machine equipped with an embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     A re-locatable operator station comprises one or more stages of fixed or extendable length that couple an operator interface to the vehicle being operated. Each of the various stages is connected to the next by a hinged joint that enables a limited range of motion. The hinged joints between each stage exhibit a reluctance to movement, such as provided by friction bearings, such that the stages will remain in a fixed orientation during normal walk behind operation, but the operator is able to relocate or reorient the operator interface when desired by applying force to the interface.  
         [0030]     The operator interface includes controller devices that may be arranged so as to present to an operator all of the man-machine interfaces, which are the devices necessary to enable a human operator to monitor and control all vehicle functions. Such man-machine interfaces may include controller devices such as any suitable means of receiving an operator&#39;s input, including switches, paddles, buttons, touch screens, hand-, finger-, or wrist-actuated single- or multi-axis joy sticks that create command signals in proportion to an operator&#39;s manual displacement or force applied; voice recognition microphones, or other input devices. The man-machine interfaces on the operator interface may also contain machine status indicators or feedback devices that communicate to the operator the machine&#39;s status, such as power source condition, machine status, visible or audible cautions or warnings. These may take the form of gages, digital readouts, liquid crystal displays, light emitting diodes, lamps, cathode ray tube displays, vibration or force-feedback mechanisms included in a controller device (e.g., as a joy stick with force-feedback capability) or other means to convey data or information to the operator.  
         [0031]     The operator interface may be held or positioned by the supporting structure at an appropriate height for the operator. The height may be adjustable within the range of typical operator statures, or within a range of operator positions. The operator interface may be held at a convenient angle to the horizontal that is appropriate to minimize the likelihood of a repetitive motion injury.  
         [0032]     The operator interface supporting structure may also be configured and arranged so that it can be lowered. A linkage may be arranged between the supporting structure and the operator interface such that the operator interface will rotate towards the vertical as it is lowered, thereby preserving the spatial orientation or angular relationship between the operator&#39;s hands and the interface. The ability to temporarily lower the operator interface enables operation of the machine underneath obstructions that would preclude use of a machine with a fixed-height operator&#39;s interface. This mode of operation may be used only temporarily and infrequently, and it is recognized that continued use of the machine with the operator interface lowered near the ground is unlikely in most applications of the present invention.  
         [0033]     Referring to  FIG. 1A and 1B , a wheeled vehicle comprises a chassis  104 , at least three wheels  101  rotateably connected to the chassis and arranged to support the same. Each wheel  101  is connected to a drive train shown in  FIG. 1B  comprising a drive shaft  200 , a support bearing  202 , a motor  204 , a speed reducer  203 , which may be a gear train or a belt and pulley assembly, and electronic controls  205 . Electrical energy to power the vehicle drive and mission hardware is supplied by a suitable source of power  206 , such as a battery, fuel cell, fossil fuel powered electrical generator, hybrid power supply module as disclosed in U.S. patent application Ser. No. 09/827,173, or any combination thereof. If employed on the vehicle, a brake assembly  201  may also be part of the drive train or may be applied to one or more of the wheels directly.  
         [0034]     Mission hardware  103  is supported by the chassis  104  and could include a raiseable payload platform, forklift mechanism, scissors lift, weapons loader, aircraft engine handling system, specialty load handling device, sensor package, fire fighting equipment, or inspection device. The mission hardware  103  may also include the mechanical, hydraulic and/or electrical actuator systems necessary to lift, lower and position a payload platform or positioner.  
         [0035]     The re-locatable operator station  100  comprises three main components: the horizontal linkage assembly  102 , the vertical linkage assembly  107 , and the operator control station  108 . Also included within the re-locatable operator station  100  are electrical cables  109  that electronically couple the operator station  108  to the vehicle  104  and/or to the electronic controls  205  therein. Such electrical cables  109  may be threaded at least partially through the structures that make up the horizontal and vertical linkages  102 ,  107 . The horizontal linkage assembly  102  is connected to one side of the vehicle chassis  104  in a suitable manner such as by being bolted to a flange or bracket as shown. The vertical linkage assembly  107  is connected at or near to the outboard end of the horizontal linkage assembly  102 . The operator control station  108  in turn is connected to the top of the vertical linkage assembly  107 . The re-locatable operator station comprising horizontal linkage assembly  102 , vertical linkage assembly  107 , and operator station  108  is arranged such that an operator can walk along with the vehicle chassis  104  while controlling its drive system and mission hardware  103 . In an alternative embodiment of the present invention, the vertical linkage assembly  107  is connected to the vehicle chassis  104  and the horizontal linkage assembly  102  is connected at one end to the top of the vertical linkage assembly  107  and at the end to the operator control station  108 . References to horizontal herein mean substantially horizontal with respect to a ground surface such as a floor, roadway, pedestal or any surface on which the operator and/or the machine or vehicle may stand. References to vertical linkage assemblies and vertical links herein mean a linkage that is capable of being oriented other than horizontally. However, as explained herein, a vertical linkage assembly may be positioned at any angle with respect to a ground surface ranging from substantially horizontal to vertical (i.e., perpendicular to horizontal). Thus, a vertical linkage assembly may be capable of being positioned substantially horizontally with respect to a ground surface.  
         [0036]     Referring to  FIG. 2 , a vehicle, comprising a chassis  104  supported by wheels  101  and equipped with mission hardware  103  as described in the preceding paragraph, is equipped with the re-locatable operator station  100 . The range in locations  105  from which an operator  106  can position the operator control station  108  and control the vehicle is depicted. The embodiment of this invention shown in  FIG. 2  permits the operator control station  108  to remain in the same orientation with respect to the vehicle chassis  104 , no matter where it is positioned within the permissible range. This feature of the illustrated embodiment may be particularly important when the vehicle  104  being controlled is an omni-directional machine (i.e., the wheels  101  comprise omni-wheels such as disclosed in U.S. Pat. Nos. 3,876,255 or 6,340,065) since this will help to ensure that the operator does not become disoriented.  
         [0037]      FIG. 3A  and  FIG. 3B  show details of the horizontal linkage  102  of the re-locatable operator station  100  presented in  FIG. 1A  and  FIG. 2 . The horizontal linkage  102  is composed of two or more sets of four bar links  21 ,  25 ,  33 ,  36  that form parallelograms when viewed from above as illustrated in  FIG. 2  and  3 B. Bracket  38  is connected to the host vehicle chassis  104  shown in  FIG. 1A , by suitable attachment structure including, for example, welds, bolts, screws, pins, quick disconnect assemblies, clevis connections, or adhesives. The connection between bracket  38  and chassis  104  should have sufficient strength and stiffness to support the rest of the re-locatable operator station  100 , including all forces imparted by the operator while controlling the machine and repositioning the operator interface  108 . An upper pivot  20  and lower pivot  37  protrude vertically from the bracket  38 . Two approximately equal length links  21 ,  36  are rotateably connected to pivots  20  and  37 . More preferably, the two links  21 ,  36  are of equal length. An upper link  21  is connected to pivot  20  and a lower link is connected to the lower pivot  37 . The pivots  20  and  37  may each be equipped with anti-friction elements (not shown) that could take the form of tapered roller bearings, angular contact ball bearings, full complement rod end ball bearings, or sliding contact bearings formed of plastic such as delrin, reinforced plastic such as glass filled nylon, metals such as bronze, or Teflon® coated or impregnated bushings. The anti-friction elements serve to permit easy rotation of both upper  21  and lower  36  links about vertical axes centered on pivots  20  and  37 , respectively. Alternatively, pivots  20  and  37  (as well as some or all pivots described herein) may be equipped with a friction element that is capable of preventing or limiting rotation about the pivot when subjected to a rotational force below a set threshold and permitting rotation about the pivot when subjected to a rotational force at or above that threshold. The friction elements may be adjustable, such as by a thread-actuated clamp that permits adjusting the force applied between two breaking surfaces, so that the rotation-force threshold can be adjusted within some range. Such friction elements may be set to hold the operator station in a fixed orientation until the operator applies sufficient force to the operator station to overcome the friction threshold and thereby reposition the operator station to a new orientation.  
         [0038]     The outboard ends of links  21  and  36  are rotateably connected to an intermediate bracket  23  on vertically oriented pivots  22  and  35 , respectively. Pivots  35  and  22  are separated by a distance D 1 . As described above for pivots  20  and  37 , pivots  22  and  35  may be fitted with anti-friction elements (not shown), such as those listed above, to enable low friction rotation of links  21  and  36  about pivots  22  and  35 . Intermediate bracket  23  is fitted with physical stops  40  and  41  that constrain the total permissible rotation of links  21  and  36  about pivots  22  and  35  to less than approximately 180 degrees. More preferably, the total permissible rotation of links  21  and  36  about pivots  22  and  35  is less than 180 degrees.  
         [0039]     Pivots  35  and  22  are separated by a horizontal distance D 2  equivalent (within reasonable tolerances) to the horizontal distance D 1  separating pivots  20  and  37 . As such, when links  21  and  36  are assembled to brackets  38  and  23  by way of pivots  20 ,  37 ,  22 , and  35 , brackets  38  and  23  are constrained to remain parallel to each other, but permitted to rotate relative to one another within the 180 degree constraint described above.  
         [0040]     The outboard end of intermediate bracket  23  is fitted with two vertically oriented pivots  34 ,  24  mounted below (pivot  34 ) and above (pivot  24 ) the bracket  23 . Two links  25 ,  33  of approximately equivalent length are rotateably connected to pivots  24  and  34 . More preferably, the two links  25 ,  33  are of equal length. Similar to the other pivots described above, pivots  34  and  24  may be fitted with antifriction elements (not shown), such as those listed above. One link  33  is connected to the lower pivot  34  and the other link  25  is connected to the upper pivot  24 . Intermediate bracket  23  is fitted with physical stops  40  and  41  that constrain the rotation of links  25  and  33  to a maximum rotation about their pivots  24  and  34  to less than 180 degrees. More preferably, the maximum rotation of links  25 ,  33  about pivots  24 ,  34  is less than 180 degrees. Pivots  24  and  34  are separated by a distance D 3 .  
         [0041]     An outboard bracket  27  is fitted with two pivots  32 ,  26 , one protruding from the bottom (pivot  32 ) and one from the top (pivot  26 ). The outboard end of link  25  is rotateably connected to the upper pivot  26  and the outboard end of link  33  is rotateably connected to the lower pivot  32 . Alternatively, link  25  could be coupled to lower pivots on brackets  23  and  26 , if link  33  is coupled to upper pivots on brackets  23  and  26 . The horizontal separation distance D 4  between pivots  26  and  32  on the outboard bracket  27  is equal (within reasonable tolerances) to the horizontal separation distance D 3  between pivots  24  and  34  on the intermediate bracket  23 . As such, when links  25  and  33  are assembled to brackets  23  and  27  by way of pivots  24 ,  34 ,  26 , and  32 , brackets  23  and  27  are constrained to remain parallel to each other, but permitted to rotate relative to one another within the less than 180 degree constraint described above.  
         [0042]     When the aforementioned links  21  and  36  are simultaneously connected to appropriate pivots on brackets  38  and  23 , the outboard bracket  27  is constrained to be parallel to the inboard bracket  38 . The inboard bracket  38  is rigidly affixed to the host vehicle chassis  104  (see  FIG. 1 ), therefore the outboard bracket  27  can be relocated relative to the vehicle chassis  104  but is constrained in height, yaw, pitch or roll relative to the chassis  104 .  
         [0043]     The pivots  20  and  37  must be of sufficient strength to support the entire re-locatable operator station  100  system of brackets, linkages, and pivots. Forces that must be resisted include the weight of the links, operator control station, any force applied by the operator, and forces caused by contact with the operating environment. Since the links  21  and  36  are parallel to each other, both shear and moment produced by the aforementioned loads must be resisted by the pivots  20  and  37 . The above described antifriction features (not shown) and incorporated into the pivots  20  and  37  must resist the same weight and moments.  
         [0044]     The two stage linkage mechanism for the re-locatable operator station  100  described above is only one example embodiment of the invention. It will be clear to those skilled in the relevant art that the two stage re-locatable operator station described above can be extended to three or more stages by simply adding more intermediate brackets and links in the manner and configurations described above.  
         [0045]      FIG. 4  shows a detailed depiction of the vertical linkage. The outboard bracket  27  is fitted with two horizontally oriented pivots  6  and  8 . Pivots  6  and  8  have their centerlines parallel to the plane formed by the two vertical pivots  26  and  32 , and are also integral with the outboard bracket  27 . Pivots  6  and  8  are parallel and separated from each other by distance D 5  made up of a horizontal distance component D 6  and a vertical distance component D 7  as shown in  FIG. 4B . Links  5  and  3  are rotateably connected to pivots  6  and  8 . In a preferred embodiment, links  5  and  3  are of equivalent length.  
         [0046]     An operator control station  1  is fitted with pivots  2  and  16  as shown in  FIG. 4A . The centerlines of pivots  2  and  16  are parallel to each other. Pivots  2  and  16  are separated by a distance D 8  that is smaller than the distance D 5  that separates pivots  6  and  8 . Links  5  and  3  are rotateably connected to pivots  2  and  16  and as such form a linkage that enables the operator control station  1  to be rotated about the outboard bracket  27  over a range of positions, from just past vertical, position  17 , to partially lowered, positions  10  and  11 , to fully lowered, position  12 . The arrangements of pivots  6 ,  8 ,  2  and  16  are such that the operator control station  1  rotates in a direction opposite to that of the linkage over the range of motion from positions  17  to  12 . This opposite rotation causes the operator control station  1  to be presented at an ergonomically convenient angle to the operator throughout the range of motion of the vertical linkage.  
         [0047]     In one or more embodiments of the invention, a third linkage, link  4 , is rotateably connected to link  5  and to link  3  with pivots  18  and  7 . In one or more embodiments, link  4  is connected to link  5  at rotateable connection point  18  intermediate between the pivots  6  and  2 . Link  4  may be variable in length, such as concentric tubes of different diameter fitted one inside the other, and fitted with an operator controlled locking mechanism  13 . When the link  4  locking mechanism  13  is engaged, thereby fixing the length of link  4 , rotation of the operator station  1  about pivots  6  and  8  is prevented, thereby fixing its height and angle to the vertical. When the link  4  locking mechanism  13  is released, thereby allowing link  4  to vary in length, the operator control station  1  can be raised or lowered by the application of manual force to raise the operator control station  1  to position  17 , or to lower it to position  12  or anywhere in between. The locking mechanism  13  may be any form of latch, clamp or pin assembly, such as a sleeve-and-set screw assembly as shown in  FIG. 4 .  
         [0048]     In another preferred embodiment, link  5  is fitted with a band or disk brake (not shown). Such a brake would consist of rotating elements rigidly connected to link  5  or link  3  or both link  5  and  3  and static elements rigidly connected to the outboard bracket  13  in the area of the pivot. Alternatively, the static elements could be positioned on the link  5 ,  3  and the rotating elements on the bracket  13 . Such static and rotating elements of a brake assembly are well known to those skilled in the art. In a preferred embodiment, the brake would have a spring loaded braking feature with a manually actuated release. The release would be actuated by the operator when he or she desires to alter the height of the operator control station  1 .  
         [0049]     In another embodiment, link  5  or link  3  is fitted with a rack and pawl mechanism (not shown) that would comprise a sector of a solid round disk centered on pivot  6  or  8  with teeth formed into its periphery. The sector would be rigidly connected to link  5  if centered on pivot  6  and link  3  if centered on pivot  8 , and would rotate with the respective link. A spring loaded pawl is rotateably connected to the outboard bracket  13  that is arranged to engage the teeth in the solid disk. Alternatively, the spring loaded pawl could be connected to the link  5 ,  3  and the sector connected to the bracket  13 . A release mechanism may take the form of a foot or hand actuated lever that will temporarily move the pawl clear of the teeth and enable the operator control station  1  to be repositioned. In this embodiment, the operator control station  1  can be positioned at any one of several discrete heights commensurate with the gear teeth pitch and number.  
         [0050]     In any of the foregoing embodiments, the links  5  and  3  are arranged to rotate about their respective pivots and are rigidly prevented from rotating about any other axis, such as by a cylindrical pivot assembly. As such, forces applied at the operator control  1  in a direction normal to the plane of rotation created by rotating links  3  and  5  about pivots  6  and  8  are transmitted to the outboard bracket  13  with little deflection of the vertical linkage  107 .  
         [0051]     A detailed view of the operator control station  108  is presented in  FIG. 5 . The operator control station  108  comprises an enclosure  29  housing linkages, electronics and wiring not shown. The side of the control station  108  enclosure  29  facing the operator is equipped with appropriate indicator and control devices, such as an energy status indicator  53 , an on/off switch  54 , an emergency stop button  52 , mission hardware controls  55 , and vehicle motion controls  50 ,  51 . Handles  28 ,  30  may be rigidly fixed to the sides of the control station enclosure  29  and arranged to permit simultaneous operation of vehicle motion controls  50 ,  51 .  
         [0052]     An energy status indicator  53  may convey the battery charge level, in the case of a battery-powered machine, or a fuel level, in the case of a fossil fuel-powered machine. In one embodiment, the energy status indicator  53  will have a warning feature to advise the operator that the energy level is below some predetermined threshold.  
         [0053]     The on/off switch  54  is used to switch the machine from off to standby, to fully operational status. The on/off switch  54  may comprise a keyed multi position rotary switch. In another embodiment the on/off switch  54  comprises a rotary switch. In yet another embodiment the on/off switch  54  comprises a push button switch.  
         [0054]     The emergency stop button  52  is arranged to stop the vehicle by disconnecting all power from the drive wheels  101  and mission hardware ( 103  in  FIG. 1 ) and setting all wheel brakes  201 . The emergency stop button  52  may be a mushroom shaped button that is configured to latch in the depressed position after being actuated and requiring that the operator twist the button to release it in order to restore machine function.  
         [0055]     Mission hardware controls  55  may consist of a two-axis joy stick arranged to accept proportional control inputs from the operator. In another embodiment of the invention, the mission hardware controls take the form of two or more joy sticks and several discrete switches.  
         [0056]     In an embodiment, thumb actuated joy sticks  51  and  50  are used to convey velocity and steering commands to the vehicle, respectively. In another embodiment, joy sticks  50  and  51  convey velocity and steering commands to the vehicle, respectively. In still another embodiment, either joy stick can be arranged to accept both velocity and steering commands to permit one handed operation.  
         [0057]     In another embodiment, the vehicle may be an omni-directional machine employing omni-directional wheels such as disclosed in U.S. Pat. Nos. 6,340,065, 3,876,255, and/or 5,374,879. In such an embodiment, vehicle motion controls  50  and  51  consist of thumb actuated joy sticks. Vehicle motion control thumb actuated joy stick  50  is arranged to accept longitudinal and transverse velocity commands from the operator, while vehicle motion control thumb actuated joy stick  51  accepts vehicle yaw rate commands from the operator. Using both the two vehicle motion control thumb actuated joy sticks  50 ,  51  the operator has complete control of the vehicle&#39;s motion. The vehicle motion control thumb actuated joy stick  50  is located in such a manner that the operator can grasp the handle  28  with four fingers of his or her right hand while the thumb rests comfortably on the joy stick  50 . Similarly, joy stick  51  is located in such a manner that the operator can grasp the handle  30  with four fingers of his or her left hand while the thumb rests comfortably on the joy stick  51 . In this way, the operator receives continuous tactile feed back on the vehicle&#39;s orientation and velocity. This arrangement also enables the operator to reposition the re-locatable operator station mechanism  102  by exerting a horizontal force on the handles  30  and  28  while simultaneously maintaining control over the vehicle via the vehicle motion control thumb actuated joy sticks  50  and  51 . Thus, it is possible to seamlessly operate the vehicle while simultaneously altering the position of the operator control station  108  with respect to the vehicle chassis  104 .  
         [0058]     In another embodiment of the invention, the operator inputs yaw and longitudinal velocity commands, which are conveyed to the machine&#39;s central controller (not shown), via thumb operated joy stick  50  and transverse velocity commands via thumb operated joy stick  51 . In this configuration, an operator is able to maneuver the vehicle with only one hand, having control of yaw rate and longitudinal velocity via thumb operated joy stick  50 , and can transit in reverse with just his or her right hand grasping handle  
         [0059]     actuating thumb actuated joy stick  50 , thus enabling the operator to face away from the vehicle and walk forward while the vehicle is operated in reverse. Having one hand firmly grasping the handle  28  will provide continuous tactile feedback to the operator on the machine&#39;s motion.  
         [0060]     Referring to  FIG. 1 , the control station  108  is linked electrically to the vehicle chassis  104  via wiring  109  that is run from the operator control station enclosure  29 , down the vertical linkage assembly  107 , along or inside the horizontal linkage assembly  102 , and into the vehicle chassis interior  104 . Operator commands pass from the control station  108  via the above described wiring  109  to the central controller (not shown) within the vehicle chassis  104 , and electrical power and feedback data from the vehicle central controller (not shown) pass via the above described wiring  109  to the control station  108  to operate displays such as the energy status indicator  53 . In another embodiment, the control station  108  is linked to the vehicle control computer via a wireless link. The wireless link may be any suitable form of wireless communication link comprising a transmitter and receiver means of communicating information and a modem, including well known data links, such as a radio frequency (e.g., two-way radio) link, an infrared link, and/or an ultrasonic link. In such an embodiment the control station  108  is powered by a rechargeable battery (not shown).  
         [0061]     Another embodiment of the horizontal linkage assembly  102  portion of the invention is presented in  FIG. 6A  and  FIG. 6B . This embodiment comprises a set of two four-bar link assemblies that form parallelograms when viewed from above. This embodiment of the re-locatable operator station is connected to the host vehicle  70  with clevis connections  50  and  69  which couple to the horizontal linkage assembly  102 . Clevis  50  and  69  may be connected to the host vehicle  70  using suitable structure such as welds, bolts, screws, or adhesives, or may be integrally cast into the host vehicle  70  structure. The connection between clevis  50  and  69  and the host vehicle chassis  70  has sufficient strength and stiffness to support the rest of the re-locatable operator station  100 , including all forces imparted by the operator while controlling the machine.  
         [0062]     Links  52  and  67  are of approximately equal length and are connected to clevis  50  and  69  with pivots  51  and  68 . Pivots  51  and  68  may each be equipped with anti-friction elements (not shown) that could take the form of tapered roller bearings, angular contact ball bearings, full complement rod end ball bearings, or sliding contact bearings formed of plastic such as delrin, reinforced plastic such as glass filled nylon, metals such as bronze, or Teflon® coated or impregnated bushings. The anti-friction element serves to permit easy rotation of both upper  52  and lower  67  links about vertical axes centered on pivots  51  and  68  respectively.  
         [0063]     The outboard ends of links  52  and  67  are rotateably connected to the intermediate bracket  53  on vertically oriented pivots  54  and  66  respectively. As described above for pivots  51  and  68 , pivots  54  and  66  may be fitted with anti-friction elements (not shown), such as those listed above, to enable low friction rotation of links  52  and  67  about pivots  54  and  66 , respectively circulating.  
         [0064]     The relative positions and configurations of host vehicle  70 , pivots  51  and  68 , and links  52  and  67  is such that the total rotation of links  52  and  67  is constrained to a total of approximately 180 degrees, or plus or minus approximately 90 degrees to either side of the clevis  50  and  69  mounting location.  
         [0065]     Pivots  51  and  68  are separated by a horizontal distance D 9  that is equal (within reasonable tolerances) to the horizontal distance D 10  separating pivots  54  and  66 . As such, when links  52  and  67  are assembled to clevis  50  and  69  and intermediate bracket  53  by way of pivots  51 ,  68 ,  54 , and  66 , intermediate bracket  53  is constrained to remain parallel to the plane in which pivots  51  and  68  lie, but is permitted to rotate relative to one another within the 180 degree constraint described above. Pivots  54 ,  56  may comprise posts extending from bracket  53 , pins that pass through bracket  53  (either rigidly attached to or freely rotating within bracket  53 ), posts extending from one or more of the links  52 ,  56 ,  62 ,  67  into a receiving hole in bracket  53 , or a similar suitable structure.  
         [0066]     Links  56  and  62  are rotateably connected to intermediate bracket  53  pivots  54  and  66  and to the outboard bracket  59  at pivots  57  and  61 . As described above for pivots  51  and  68 , pivots  54  and  66  may be fitted with anti friction elements (not shown) to enable low friction rotation of links  56  and  62  about pivots  54  and  66  respectively.  
         [0067]     The horizontal linkage  102  will include physical stops to prevent motion of the assembly beyond desired ranges. For example, in one embodiment, link  56  is fitted with a physical stop  71  that will prevent clockwise rotation (when viewed from above) of the centerline of link  56  about pivot  54  beyond a line connecting pivots  54  and  66 . Likewise, link  62  is fitted with a physical stop  72  that prevents anticlockwise rotation (when viewed from above) of the centerline of link  62  beyond a line connecting pivots  54  and  66 . The total range of motion of the links  56  and  62  is thereby constrained to a total of approximately 180 degrees, or approximately 90 degrees to either side of the intermediate bracket  53 .  
         [0068]     Intermediate bracket pivots  54  and  66  are separated by a horizontal distance D 10  approximately equal to the horizontal distance D 11  separating outboard bracket pivots  57  and  61 . More preferably, the two horizontal distances are equal. As such, when links  56  and  62  are assembled to intermediate bracket  53  and outboard bracket  59  by way of pivots  54 ,  66 ,  57 , and  61 , outboard bracket  59  is constrained to remain parallel to the plane in which pivots  54  and  66  lie, but is permitted to rotate relative to one another within the aforementioned 180 degree constraint.  
         [0069]     As one can see from the foregoing discussion, outboard bracket  59  is constrained to be parallel to the plane described by pivots  51  and  68 . Clevis  50  and  69  are rigidly affixed to the host vehicle  70  chassis, therefore the outboard bracket  59  can be relocated relative to the vehicle  70  chassis but is constrained in height, yaw, pitch and roll directions relative to the chassis.  
         [0070]     The clevis  50  and  69  and associated pivots  51  and  68  should be of sufficient strength to support the entire re-locatable operator station system of brackets, linkages, and pivots. Forces that must be resisted include the weight of the links, operator control station, any force applied by the operator, and forces caused by contact with the operating environment. Since the links  52  and  67  are parallel to each other, both shear and moment produced by the aforementioned loads are resisted by the pivots  51  and  68 .  
         [0071]      FIG. 7A  and  FIG. 7B  depicts another embodiment of the invention that differs in the way the horizontal linkage assembly  125  connects to the host vehicle  117  and in how the horizontal linkage assembly  125  is supported. In this embodiment, the horizontal linkage assembly  125  couples to and interfaces with the host vehicle  117  via a hinged bracket assembly  126 . The hinged bracket assembly comprises a bracket  116  that is connected to the host vehicle  117  via bolts, welds, adhesives, or other appropriate means (not shown). Bracket  116  is fitted with clevis  114  that engages the inboard bracket  110  by way of round pin  115  and clevis  113 . This arrangement enables the entire horizontal linkage  125  to rotate about a horizontal axis coincident with the centerline of round pin  115 . Links  21  and  36  are rotatably connected to inboard bracket  110  at vertically oriented pivots  111  and  112 .  
         [0072]     The rest of the horizontal linkage assembly  125  is similar to the aforementioned descriptions of the horizontal linkage assembly, with the exception of the outboard bracket  118 . The outboard bracket  118  is fitted with a mounting interface  119  arranged to accept a caster wheel assembly  124 . The caster wheel assembly  124  consists of a vertical bearing  120  that enables the wheel  123  to flag about a vertical axis centered on the bearing  120 . The lower part of the bearing  120  is connected to the wheel  123  by suitable bracketry  121  and axle  122 . As the operator maneuvers the host machine  117 , the caster wheel  124  will automatically orient itself to follow its motion.  
         [0073]     The horizontal linkage assembly  125  is supported and constrained in longitudinal, lateral, and vertical directions at the inboard end by the above described hinged bracket assembly  126 . This hinge assembly  126  also supports and constrains the inboard bracket  110  in yaw and roll. The horizontal linkage assembly  125  is permitted to pitch up or down about pin  115 . The outboard bracket  118  is supported by the caster wheel  124  which rests on the running surface  118 .  
         [0074]     When the host machine  117  is operated over an uneven surface  118 , the operator interface will remain at a constant height over the surface where the caster wheel  124  makes contact. This embodiment enables a vehicle  117  to transition from level surfaces to an incline while the operator interface horizontal linkage assembly  125  is fully extended without binding or dragging on the running surface. This embodiment of the invention also enables the invention to remain at a constant height above a surface  118  when transitioning from an incline to level or declined running surface.  
         [0075]     Now referring to  FIG. 8 , the re-locatable operator station is shown employed on an aircraft jet engine handler. This figure shows a jet engine  150  supported by brackets  151  that interface with parallel rails  152 . The parallel rails  152  are in turn supported by a lifting mechanism  153 . The lifting mechanism is connected to a chassis  154 . Power to lift and lower the engine  150  via the lifting mechanism  153  can be provided manually, by battery powered hydraulics, or by other suitable means. The chassis  154  is depicted as being supported over the running surface by four omni-directional wheels  155 .  
         [0076]     The re-locatable operator station horizontal linkage assembly  117   157  is shown as being mounted to the side of the engine handler chassis  114154 . In another embodiment, the re-locatable operator station horizontal linkage assembly  117   157  is mounted to the front or rear of the chassis  1154  or to a side. The vertical linkage assembly  158  is mounted to the outboard end of the horizontal linkage assembly  157 . The operator control station  159  is in turn mounted on top of the vertical linkage assembly  158 . In this configuration, an operator can maneuver the engine handler laterally to position it underneath an aircraft (not shown) for engine installation or removal. The ability to relocate the operator station enables the operator to get a close-up view of one or another end of the assembly as it is being maneuvered, while receiving intuitive and tactile feedback on the machine&#39;s orientation, longitudinal and transverse velocity, and yaw rate. The operator&#39;s station can be relocated when maneuvering amongst the aircraft&#39;s landing gear, weapons, sensor pods, or fuel tanks. The vertical linkage assembly  158  can be lowered to pass beneath the aircraft.  
         [0077]     Now referring to  FIG. 9 , the re-locatable operator station is shown employed to control an aerial work platform. This embodiment comprises a mobile aerial work platform chassis  80  supported by wheels  81 . The horizontal linkage  82  is connected to the aerial work platform&#39;s chassis  80  by suitable structure such as bolts, welds, adhesives, or other means (not shown). The vertical linkage assembly  85  is connected to the horizontal linkage assembly  82  as described above. The operator control station  83  is mounted atop the vertical linkage assembly  85  as described earlier. In use, an operator (not shown) would be able to move the operator control station  83  to a position directly behind the chassis  80  while maneuvering through a narrow passageway. The operator could then relocate the operator control station  83  to the left of the chassis  80  by simply applying manual force. The operator can then view the work platform  84  from the side, which would be beneficial when positioning the platform near an overhead obstruction. Alternatively, the operator can collapse the horizontal linkage and thereby position the operator control station  83  directly behind the chassis  80  to present a minimum footprint while maneuvering or during storage.  
         [0078]     Now referring to  FIG. 10A and 10B , the re-locatable operator station is employed to control an omni-directional long load transporter. The transporter chassis  91  is supported by four omni-directional wheels  92 , in  FIG. 10B . Each omni-directional wheel  92  is similar to those disclosed in U.S. Pat. Nos. 6,340,065, 3,876,255, and/or 5,374,879. In each case, the omni-directional wheel  92  comprises a frame rotateably connected to the chassis  91 . The frame supports free spinning rollers which contact the running surface. Each omni-directional wheel  92  is driven by machinery (not shown) in such a manner as to enable the entire vehicle to move in any direction desired by and under the operator&#39;s control. The horizontal linkage  93  is connected to the long load transporter chassis  91  by suitable structure, such as bolts, welds, adhesives, or other means (not shown). The vertical linkage assembly  94  is connected to the horizontal linkage assembly  93  as described above. The operator control station  95  is mounted atop the vertical linkage as described above. In this embodiment, an operator can position himself behind and in line with the chassis  91  and long load  90 . When transporting a shorter load, the operator can partially collapse the horizontal linkage assembly  93  such that the overall length is minimized. When negotiating around blind corners, an operator can position the controls to the outside of the turn by simply pushing the operator station  95  to the desired position. The operator can then position himself to view the machine and its payload  90  around the blind corner while simultaneously maneuvering the machine. The operator control station  95  will remain in the same orientation in yaw, and the operator&#39;s intuitive understanding of the relationship between velocity commands and vehicle motion is unchanged. The operator maintains his grip on the operator control and so all machine motion is conveyed to the operator via tactile feedback.  FIG. 10A  illustrates an alternative embodiment of the long load transporter where the wheels  96  are conventional wheels that are steerable.  
         [0079]     Now referring to  FIG. 11 , the above described omni-directional long load transporter, comprising a chassis  91 , omni-directional wheels  92 , and payload  90 , is shown being maneuvered under an overhead obstruction  97 . In this case, the horizontal linkage  93  is arranged to place the operator control station  95  behind and in line with the payload  90 . The vertical linkage assembly  94  has been lowered by the operator to pass beneath the obstruction  97 . One can see from this depiction that the operator control station could similarly be lowered to pass beneath the payload  90  when and if such is necessary.  
         [0080]      FIG. 12  contains an embodiment of the invention used in a ride-on machine. In this embodiment the host machine  140  chassis  142  is supported by one or more wheels  141  and powered by machinery (not shown). The chassis provides a riding platform  147  and supports mission hardware  143 . The mission hardware  143  could take the form of material handling mechanisms such as lift forks, robotic arms, grippers, scissors lift, large roll handling, die or forge manipulator, or spool handling; construction devices such as a front loading shovel, back hoe, steam roller, auger, pile driver, directional drill, hammer drill, penetrometer, or jackhammer; military equipment such as a mine flail, obstacle breeching device, cannon, mortar, or flamethrower; or agricultural equipment such as combine, plough, rake, or tiller. The mission hardware  143  may require that the operator (not shown) be able to alternately view its function from either side of the machine  140 . The horizontal linkage assembly  144  is affixed to the chassis  142 . The vertical linkage assembly  145  is connected to the horizontal linkage  144 . The operator control station  146  is affixed to the top of the vertical linkage assembly  145 .  
         [0081]     In this embodiment, an operator (not shown) can control a ride on machine  140 , such as by standing on a platform  147 , while simultaneously retaining the ability to move from one side of the machine  140  to the other. The ability to move about on platform  147  by repositioning the operator station  146  enables an operator to visually observe the operation of the mission hardware  143  while maintaining control over the machine  140  and mission hardware  143 .  
         [0082]     This embodiment shows only a single stage horizontal linkage assembly  144 . A person skilled in the arts associated with this patent will see that a single stage horizontal linkage assembly will function similarly to the aforementioned two stage linkage assemblies, except that the outboard bracket will be constrained to a semi circular arc centered on the inboard bracket. However, it is envisioned that ride-on vehicle applications may also employ two- and three-stage horizontal linkage assemblies if suitable for the vehicle&#39;s mission.  
         [0083]      FIG. 13  illustrates an embodiment of the invention used to support an operator&#39;s control station for a tracked machine  130 . In this embodiment. the host machine  130  chassis  132  is supported by one or more tracks  131  and powered by machinery (not shown). The chassis further supports mission hardware  133 . Mission hardware  133  could take the form of material handling mechanisms such as lift forks, robotic arms, grippers, scissors lift, large roll handling, die or forge manipulator, or spool handling; construction devices such as a front loading shovel, back hoe, steam roller, auger, pile driver, directional drill, hammer drill, penetrometer, or jackhammer; military equipment such as a mine flail, obstacle breeching device, cannon, mortar, or flamethrower; or agricultural equipment such as a combine, plough, rake, or tiller. The mission hardware  133  may require that the operator (not shown) be able to alternately view its function from either side of the tracked machine  130 . The horizontal linkage assembly  134  is affixed to the chassis  132 . The vertical linkage assembly  135  is connected to the horizontal linkage assembly  134 . The operator control station  136  is affixed to the top of the vertical linkage assembly  135 .  
         [0084]     In this embodiment, an operator (not shown) can control a walk behind tracked machine  130  while simultaneously retaining the ability to move from one side of the machine  130  to the other to visually observe the operation of the mission hardware  133 , all the while maintaining control over the machine  130  and mission hardware  133 .  
         [0085]     The stages and operator interface are configured to enable relocation by the operator at will by simply applying manual force to the operator interface. In operation, the operator will normally walk behind the machine being controlled. The operator will have a clear view of the machine, payload, and any mission hardware, but will be able to view the far side. Without the benefit of the present invention, a machine operator may require a second person to serve as a spotter to assist in guiding the machine through a constricted passageway or in close proximity to other marked machines or fixed obstacles. The present invention enables the operator to rapidly and simply move to other locations around the vehicle while remaining in direct physical contact with the machine. Unique features of the present invention also enable an operator to move about a functioning machine as described above while maintaining an azimuthally similar relationship between the operator interface and the machine&#39;s centerline. This may be an important benefit when controlling a vehicle that is capable of omni-directional motion.  
         [0086]     The various embodiments of the present invention described herein enable an operator to readily and continually reposition the operator&#39;s interface location with respect to the vehicle. This enables walk-behind operation from different vantage points that permit viewing the vehicle and its payload as it is maneuvered. This is of particular use when maneuvering in constrained spaces while handling large objects with protruding features that can be damaged by slight contact with obstacles.  
         [0087]     Another advantage of the present invention is the enabled ability to operate a machine in a walk behind manner with the operator receiving tactile feedback on the machine&#39;s longitudinal, transverse, and rotational motion.  
         [0088]     Another advantage of the present invention is the reduction in risk to the operator of being inadvertently pinned and injured between the operator interface and an obstruction while backing up, since the linkage will retract easily with only slight force.  
         [0089]     Another advantage of the present invention is the ability to raise the operator interface to differing heights to permit operators of different statures to operate a walk behind machine with correct ergonomics.  
         [0090]     Yet another advantage of the present invention is the ability to lower the operator interface to enable a machine, payload, and operator to be driven underneath obstructions, while the interface is arranged to preserve the best possible ergonomics while doing so.  
         [0091]     Still another advantage of the present invention is the ability to collapse the operator interface into a small length, and so reduce the floor space required for storing the machine to a minimum.  
         [0092]     Another advantage of the invention is the ability to extend or reposition the operator interface to accommodate long or otherwise oversized loads that extend beyond the vehicle&#39;s perimeter.  
         [0093]     While various embodiments of the present invention have been described above and in the drawings, it should be understood that they have been presented only as examples, and not as limitations. The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.