Patent Publication Number: US-2021188353-A1

Title: Utility vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation U.S. patent application Ser. No. 16/224,779, filed Dec. 18, 2018, which is a continuation of U.S. patent application Ser. No. 15/168,945, filed May 31, 2016, which claims benefit of U.S. Provisional Patent Application No. 62/168,265, filed May 29, 2015, all of which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure is directed to a utility vehicle, and more particularly, to a utility vehicle capable of off-road travel as well as having a load-carrying capacity. 
     Description of Related Art 
     Utility vehicles (UVs) and similar utility machines (UMs) are available for a variety of industries and usages, but they have some limitations. These machines are non-highway and are generally off-road and therefore subject to a variety of terrain, ambient, environmental and load conditions which cannot be adequately addressed with currently available vehicles. For example, many types of off-road vehicles are targeted for the fun and adventurous experience such as driving on sand dunes or traversing rocks and canyons in a recreational manner. While these recreational vehicles are highly mobile, they generally do not provide significant utility or load-carrying capabilities. Other types of off-road utility vehicles are workhorse-type vehicles that are low-speed, high-utility configured to transport heavy loads for landscaping, or the like, over ground that is not road-quality. 
     Frames and chassis of the UVs/UMs are typically made from metallic or composite structural components, but these generally do not provide buoyancy. Unless a speed/steering compensating control system is used, turning maneuvers can cause tire slippage or spinning, with associated pushing or plowing. 
     SUMMARY 
     Advantages of the present disclosure will become more apparent to those skilled in the art from the following description of the embodiments of the disclosure which have been shown and described by way of illustration. As will be realized, the described methods and apparatus are capable of other and different embodiments, and their details are capable of modification in various respects. 
     According to one aspect of the subject application, a utility vehicle is provided. The utility vehicle includes a frame that includes two opposing lateral sides. The utility vehicle also includes a power source connected to the frame and a plurality of steerable structures rotatably connected to the frame. The utility vehicle further includes a plurality of ground engaging members operatively connected to the plurality of steerable structures. The utility vehicle still further includes an operator seating area, where a steering control and a speed control for controlling the plurality of ground engaging members are located. The utility vehicle also includes a plurality of controllers configured to receive input from the steering control and the speed control. The utility vehicle further includes a plurality of motors connected to the plurality of steerable structures, wherein the motors are configured to drive the plurality of ground engaging members at different speeds and in different directions. At least one of the plurality of controllers is configured to integrate a steering input received by the steering control with a speed input received by the speed control to effect rotation of the plurality of steerable structures and effect rotation of the plurality of ground engaging members. The steering control, speed control, plurality of controllers, plurality of steerable structures, and plurality of motors are configured to work together to control the rotational speed of all of the plurality of ground engaging members based upon a steering angle input to the steering control and based upon which of the opposing lateral sides a particular ground engaging member of the plurality of ground engaging members is connected. 
     According to another aspect of the subject invention, a utility vehicle is provided. The utility vehicle includes a frame that includes two opposing lateral sides. The utility vehicle also includes a power source connected to the frame and a plurality of steerable structures rotatably connected to the frame. The utility vehicle further includes a plurality of ground engaging members operatively connected to the plurality of steerable structures. The utility vehicle still further includes a plurality of braking mechanisms connected to the plurality of steerable structures. The plurality of braking mechanisms are configured to apply a braking force to the plurality of ground engaging members. The utility vehicle still further includes an operator seating area, where a steering control and a speed control for controlling the plurality of ground engaging members are located. The utility vehicle also includes a plurality of controllers configured to receive input from the steering control and the speed control. The utility vehicle further includes a plurality of motors connected to the plurality of steerable structures, wherein the motors are configured to drive the plurality of ground engaging members at different speeds and in different directions. At least one of the plurality of controllers is configured to integrate a steering input received by the steering control with a speed input received by the speed control to effect rotation of the plurality of steerable structures and effect rotation of the plurality of ground engaging members. The steering control, speed control, plurality of controllers, plurality of steerable structures, and plurality of motors are configured to work together to effect Ackermann steering on all of plurality of ground engaging members. Half of the plurality of ground engaging members are located on one of the opposing lateral sides and experience a braking force when on an inner side of a turning operation. 
     According to another aspect of the subject application, a utility vehicle is provided. The utility vehicle includes a frame that includes two opposing lateral sides. The utility vehicle also includes a power source connected to the frame and a plurality of steerable structures rotatably connected to the frame. The utility vehicle further includes a plurality of ground engaging members operatively connected to the plurality of steerable structures. The utility vehicle still further includes an operator seating area, where a steering control and a speed control for controlling the plurality of ground engaging members are located. The utility vehicle also includes a plurality of controllers configured to receive input from the steering control and the speed control. The utility vehicle further includes a plurality of motors connected to the plurality of steerable structures, wherein the motors are configured to drive the plurality of ground engaging members at different speeds and in different directions. At least one of the plurality of controllers is configured to integrate a steering input received by the steering control with a speed input received by the speed control to effect rotation of the plurality of steerable structures and effect rotation of the plurality of ground engaging members. A number of ground contacting members are located on both of the two opposing lateral sides and a track width of the utility vehicle is adjustable. 
     According to another aspect of the subject application, a utility vehicle is provided. The utility vehicle includes a frame that includes high-strength low-alloy sealed tubular members. The utility vehicle also includes a power source connected to the frame and a plurality of steerable structures rotatably connected to the frame. The utility vehicle further includes a plurality of ground engaging members operatively connected to the plurality of steerable structures. The utility vehicle still further includes a plurality of braking mechanisms connected to the plurality of steerable structures. The plurality of braking mechanisms are configured to apply a braking force to the plurality of ground engaging members. The utility vehicle also includes an operator seating area, wherein a steering control and a speed control for controlling the ground engaging members are located within the operator seating area. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       These and other features of the present disclosure, and their advantages, are illustrated specifically in embodiments of the disclosure now to be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: 
         FIG. 1  is a perspective view of an example utility vehicle according to at least one embodiment of the present disclosure showing a track assembly as a ground engaging member; 
         FIG. 2  is a perspective view of the utility vehicle of  FIG. 1  with a number of components removed in order to detail a frame construction; 
         FIG. 3  is a simplified view of an articulating beam axle as used on the utility vehicle of  FIG. 1  showing wheel/tire provisions for the ground engaging member; 
         FIG. 4  is a schematic of an adjustable track width of the articulating beam axle of  FIG. 3 ; 
         FIG. 5A  is a schematic of one example power scheme of the utility vehicle of  FIG. 1  showing a set of motors connected in parallel; 
         FIG. 5B  is a schematic of one example power scheme of the utility vehicle of  FIG. 1  showing a set of motors connected in series; 
         FIG. 6  is a graphical representation of steering wheels of the utility vehicle; 
         FIG. 7  is a graphical representation of the turning radius for the utility vehicle; 
         FIG. 8  is a schematic of the turning radius for the utility vehicle showing an Ackermann geometry; 
         FIG. 9  shows the turning radius for various vehicles; 
         FIG. 10A  is a schematic of Ackermann steering geometry for a two-wheel steer vehicle; and 
         FIG. 10B  is a schematic of Ackermann steering geometry for a four-wheel steer vehicle. 
     
    
    
     It should be noted that all the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments. Accordingly, the drawing(s) and description are to be regarded as illustrative in nature and not as restrictive. 
     DETAILED DESCRIPTION 
     A new design for an amphibious all-wheel drive/all-wheel steering utility vehicle is provided. The utility vehicle will provide off-highway transportation for two 95 th  percentile adult males (or the equivalent) and cargo on a platform which provides amphibious capability, outstanding maneuverability, superb stability and traction using an efficient hybrid-electric or hydrostatic traction drive system. Power can be provided by an efficient and low-emission spark or compression-ignition engines or stored energy devices, including internal combustion engines, hybrid-electric engines, electric engines, and the like. 
     Turning to  FIG. 1 , a utility vehicle  20  includes a frame  24  (best seen in  FIG. 2 ) providing a base upon which individual components of the utility vehicle  20  can be mounted. In one example, the frame  24  can be constructed of tubular members  26  comprising high-strength low-alloy steel (HSLA). HSLA frame members can provide more desirable mechanical properties, increased resistance to corrosion, and lighter weight in cross-section when compared to more common steel compositions such as carbon steel. The tubular members  26  can be sealed in order to increase the buoyancy of the utility vehicle  20 . Tubular members  26  can also provide convenient protected spaces for routing wire harnesses and tubing throughout the utility vehicle  20 . 
     Turning to  FIG. 2 , the frame includes two opposing lateral sides  28 ,  30 . For example, the lateral sides  28 ,  30  can be the left and right sides of the utility vehicle  20 . The utility vehicle  20  also includes an operator seating area  34 , generally shown in  FIG. 2  as a pairing of two seats  36 . It is to be understood that the operator seating area  34  can be on the left or right sides of the vehicle centerline  74  and can be further enclosed with a roof, a floor, doors, instrument panel, etc., though these elements are not shown in  FIG. 2  for the sake of showing the arrangement of the main elements of the utility vehicle  20 . As best seen in the schematic view of  FIG. 5A , the operator seating area  34  further includes a steering control and a speed control for controlling travel speed and direction of the utility vehicle  20 . 
     The utility vehicle  20  includes a power source  38  connected to the frame  24 . Any suitable power source can be used with the utility vehicle  20  including, but not limited to, mechanical power devices such as spark-ignition (gasoline) or compression-ignition (diesel) internal combustion engines or electric power provided by stored energy devices such as batteries, fuel cells, etc. Regardless of the type, the power source  38  provides energy to propel the utility vehicle  20  and supply power to other ancillary systems as needed. 
     Continuing with  FIG. 2 , the utility vehicle  20  includes a plurality of steerable structures  40  rotatably connected to the frame  24 . Each steerable structure  40  has a ground engaging member  44  operatively connected to it, such that when the steerable structure  40  is rotated relative to the frame  24 , the ground engaging member  44  rotates with the steerable structure  40 . In most examples, the steerable structure  40  is configured to rotate about a substantially vertical axis  44 . Only one steerable structure  40  is shown in  FIG. 2 , however, it is to be understood that one steerable structure  40  can be located at each traditional corner of the utility vehicle  20 . 
     The utility vehicle  20  also includes a plurality of ground engaging members  46  that are operatively connected to the plurality of steerable structures  40 , typically one ground engaging member  46  per each steerable structure  40 . As shown in  FIGS. 1 and 2 , one example of a ground engaging member  46  is a track assembly  48 . Any suitable track assembly can be used; one example is described in U.S. patent application Ser. No. 14/724,172. Other examples of ground engaging members include, but are not limited to, pneumatic tires and non-pneumatic tires as shown in  FIG. 3 . In one example, the utility vehicle  20  includes wheel/tires or track assemblies to support and transfer loading of the utility vehicle  20  through suspension elements to the terrain it traverses. 
     In another example, the utility vehicle  20  includes pneumatic wheel/tires providing large terrain contact areas and internal air/nitrogen volumes to create the buoyancy necessary for floatation of the utility vehicle  20 . In yet another example, the utility vehicle  20  includes non-pneumatic wheel/tires providing many of the features of pneumatic wheel/tires but with high axial stiffness, increased terrain contact areas, and “no-flat” performance. 
     In still another example, the utility vehicle  20  includes track assemblies providing increased ground contact area (fore-and-aft) exhibiting lower ground pressure, high axial stiffness, adjustable radial stiffness and spring rates, and no-flat performance. 
     Pneumatic tire(s) of a wheel assembly or non-pneumatic tire(s) of a wheel assembly are used to provide traction drive for the utility vehicle  20  in some configurations. Pneumatic tires provide deflections radially, laterally (axially), and torsionally whereas non-pneumatic typically provide high axial stiffness, whereas tracks have high lateral &amp; torsional stiffness with varying amounts of radial stiffness. The utility vehicle  20  can include both pneumatic and non-pneumatic tires as well as track assemblies as ground engaging members to provide traction between the vehicle and the ground, or any combination thereof. The pneumatic tires provide relatively large terrain contact areas and large internal volumes for air/nitrogen, with the additional benefit of buoyancy. Some current utility vehicles utilize non-pneumatic tires that are designed to match the radial and torsional characteristics of pneumatic tires, but with higher lateral stiffness (this minimizes slip angle during turning and lateral loading) and a larger terrain contact patch. One advantage of replacing the pneumatic and non-pneumatic tires with track assemblies  48  is to eliminate slip angle during turning and lateral loading, which increases the areas of terrain contact (therefore improving traction) and a decrease in ground contact pressure. The weight of the utility vehicle  20  is spread out over a significantly larger area using track assemblies, such that the ground contact pressure can be reduced eight-to-ten-fold when compared to pneumatic or non-pneumatic tire use. Track assemblies, or tracked drive systems, typically resolve performance issues such as limited traction, minimal floatation and terrain deformation that could limit machine utilization with restricted or limited utilization of attachments. These limitations have a direct effect on machine directional and steering control, stability, flexibility, and functionality with attachments connected to the utility vehicle  20 . 
     A variety of suspension schemes can be used to help smooth the ride of the utility vehicle  20 . As shown in  FIG. 3 , suspensions employing an axle comprising an articulating beam  50  are particularly useful in off-road applications for utility vehicles because they offer great strength and load capacity, high lateral stability, good ride comfort, and only tend to raise load height minimally when small changes in the terrain (bumps, dips, etc.) are encountered. Articulating beam axles are hollow assemblies with a pivot point  54 , about which there are portions  56 ,  58  of the articulating beam  50  on each side of the pivot point  54 . While not shown, each end of the articulating beam  50  can incorporate a yoke that accepts a complimentary steerable structure  40 . Pivoting of the articulating beam  50  allows for wheel/tire and tracks movements with bounce (jounce) and rebound forces being controlled by adjustable mechanical or air springs and shock-absorber assemblies  60 . Other examples of suspension equipment can include adjustable mechanical springs (coil, leaf, torsion, and the like) and hydraulic or pneumatic spring devices. In another example, the utility vehicle  20  includes manually or power adjustable suspension elements. 
     Turning to  FIG. 4 , the articulating beam  50  also allows for simple track width changes that accommodate relatively narrow widths and relatively wide widths. Track width can be defined from a centerline  64  of the right side ground engaging member  46  to the centerline  66  of the left side ground engaging member  46 . For illustrative purposes,  FIG. 4  shows ground engaging members  46  at different widths  68 ,  70  between the centerlines  64 ,  66  of the ground engaging members  46  to the centerline  74  of the utility vehicle  20 . For example, dimension  68  (narrow) on the left side can be used for wheels and/or tires and dimension  70  (wide) on the right side can be used for track assemblies. In one example, the articulating beam  50  is a hollow axle that enables a tube-in-a-tube connection with the yoke  76 . In another example, one or both of the articulating beam  50  and the yoke  76  can include a set of holes and/or slots  78  enabling manual changes to the track width using a threaded fastener connection. The hollow axles  50  and tubular frame also help provide buoyancy for the utility vehicle  20  because they are sealed via threaded plugs (not shown). As with the tubular frame members  24 , the articulating beam  50  can comprise HSLA. 
     In another example of the utility vehicle  20  described above, the utility vehicle  20  includes articulating beam axles that transfer the vertical and lateral load reactions of the utility vehicle  20  that occur during normal operations, turning maneuvers, and side hill operations, from the traction motors (described below) through the ground engaging members  46  to the frame. 
     In another example of the utility vehicle  20 , the utility vehicle  20  includes pivot beam axles (essentially ½ of an articulating beam  50  axle split at the pivot point  54 ) creating suspension elements that react to terrain variations independently from one another. 
     Turning to  FIG. 5A , a schematic representation of an example drive system  80  of the utility vehicle  20  is shown. As previously discussed, the operator seating area  34  includes a steering control and a speed control for controlling travel speed and direction of the utility vehicle  20 . In one example, the steering control and speed control can be one input device  84 . The utility vehicle  20  includes a plurality of controllers  86 ,  88 ,  90  configured to receive input from the steering control and the speed control. During operation of the utility vehicle  20 , an operator provides an input (e.g., physical motion of the input device  84  to direct travel speed and direction of the utility vehicle  20 . At least one of the plurality of controllers  86 ,  88 ,  90  is configured to integrate a steering input received by the steering control with a speed input received by the speed control to effect rotation of the plurality of steerable structures  40  and effect rotation of the plurality of ground engaging members  46  (best seen in  FIGS. 1 and 3 ). In the shown example, the steering control and the speed control have been unified into the input device  84 , however, separate controls such as a steering wheel and a “gas pedal” can be provided in other examples. Alternatively, other control devices can be provided including, but not limited to: a pair of steering levers positioned adjacent to the lateral sides of the user, a joystick, or any other steering mechanisms. 
     Continuing with  FIG. 5A , the input device can include a sensor  94  to determine the input provided by the operator and convert a physical motion to an electrical signal. Controller  86  is in electrical communication with the sensor  94  via connection  96 . Controller  86  integrates the steering input and the speed input (now represented as an electrical signal) and determines appropriate rotation angles for the steerable structures  40  and rotation speeds for the ground engaging members  46 . Controller  86  is in electrical communication with controllers  88 ,  90  via connections  98 ,  100  represented by arrows. Controller  88  dictates rotation of the steerable structures  40  and rotation of the plurality of ground engaging members  46  on one of the opposing lateral sides  28  of the utility vehicle  20  (i.e., the left side). Similarly, controller  90  conducts the same operations on the other of the opposing lateral sides  30  (i.e., the right side). 
     The utility vehicle  20  also includes a plurality of motors  104  connected to the plurality of steerable structures  40 . The motors  104  are configured to drive the plurality of ground engaging members  46  at different speeds and in different directions. Any suitable motor can be used, including, but not limited to, electric drive motors, hydraulic drive motors hydrostatic drives, etc. Transfer of power to the ground engaging members  46  is accomplished by individual motors attached to steerable structures  40  connected to the articulating beam axles. The drive motors  104  incorporate hubs  108  with lug-bolts to allow wheel/tires and tracks to be directly attached to the drive motors  104 . Track assembly pivoting allows each track assembly to climb over obstacles and follow terrain contours. Controllers  88 ,  90  are in electrical communication with the motors  104  via connections  110 .  FIG. 5A  shows the plurality of motors  104  connected in parallel, while  FIG. 5B  shows the motors  104  connected in series. 
     In the shown example, the motors  104  can take the place of the steerable structures  40  and rotate about a kingpin  112 . Each kingpin  112  can include a sensor  114  to determine the rotation angle of the motor  104 , and this rotational position information is relayed back to the controller  86  via connection  116 . In one example, only one kingpin  112  includes a sensor  114 , for example, the front left kingpin  112 . 
       FIGS. 5A and 5B  also show electrical generators  118  to convert mechanical energy from the power source  38  into electrical energy to be supplied to the control system of the utility vehicle  20 . In some cases, the power source  38  can be batteries or a fuel cell, in which case the electrical generators  118  can be omitted. 
     As a brief summary of the drive systems shown in  FIGS. 5A and 5B , one example includes an internal combustion engine or hybrid engine as power source  38 ; generator  118 ; an inverter  119 ; controllers  86 ,  88 ,  90 ; electric drive motors as motors  104 ; and braking mechanism  120  (described below). Another example includes an internal combustion engine or hybrid engine as power source  38 ; hydrostatic pump(s)  124 ; controllers  86 ,  88 ,  90 ; hydrostatic motors as motors  104 ; and braking mechanism  120 . Yet another example includes batteries or fuel cells as power source  38 ; controllers  86 ,  88 ,  90 ; electric drive motors as motors  104 ; and braking mechanism  120 . Various combinations of these components and drive systems are also contemplated. 
     In the described examples, the steering control, the speed control, the controllers  86 ,  88 ,  90 , the steerable structures  40 , and the motors  104  are configured to work together to control the rotational speed of all of the ground engaging members  46  based upon a steering angle input to steering control and based upon which of the opposing lateral sides  28 ,  30  a particular ground engaging member  46  is connected. Additionally, in some examples, feedback to the controllers  86 ,  88 ,  90  comes from speed sensors (not shown) which are sometimes integrated into the braking mechanisms  120 , but sometimes they are integrated into the motors  40 . 
     In a more particular example, the steering control, the speed control, the controllers  86 ,  88 ,  90 , the plurality of steerable structures  40 , and the motors  104  are configured to work together to, during a turning operation, reduce the rotational speed of the ground engaging members  46  connected to the inner lateral side of the utility vehicle  20  in order to reduce a turning radius of the utility vehicle  20 . In other words, during a utility vehicle turn, the ground engaging members  46  on the inside of the turn can experience a braking operation from a braking mechanism  120 . Any suitable braking mechanism can be used, including, but not limited to, friction brakes, regenerative brakes, or slowing of a hydrostatic device. 
     In yet another example, the steering control, the speed control, the controllers  86 ,  88 ,  90 , the plurality of steerable structures  40 , and the motors  104  are configured to work together to, during a turning operation, to effect Ackermann steering on all of the ground engaging members  46 . 
     The steering geometry shown in  FIG. 6  results in the inside ground engaging member  46  turning a smaller radius than the outside ground engaging member  46 . This allows the utility vehicle  20  to travel around a curve without scrubbing the tires or track assemblies if the steering linkage is designed to provide “Neutral” or “ 0 ” Ackermann. The steering linkage does not need to produce true Ackermann which is a combination of the steered angle and the tire slip angle produced by the cornering force. Arrows  130  represent the steered angle while arrows  134  represent the direction of travel. Arrow  136  represents a cornering force. The slip angle  138  on the outside ground engaging member  46  (left side) is greater than the slip angle  140  of the inner ground engaging member  46  (right side) and this produces varying degrees of dynamic Ackermann effect. 
     There can be significant de-tracking forces developed on the described track assemblies  48  during turning maneuvers, but the exemplary utility vehicle  20  employs all-wheel-steering so that the steering angles can be minimized to about 70% of that necessary for single-axle steering systems. For the example shown in  FIGS. 6-8 , less than 35 degrees inside and about 18 degrees outside for a 10-foot diameter tire circle (effective radius of 50-inches with 49-inch track width and 66-inch wheelbase), compared to 48 degrees inside and 31 degrees outside for a single steer axle (same track and wheelbase, effective radius of 60-inches). As shown in  FIG. 7 , the typical pivot point of a vehicle is represented by point  144  while the point for a minimum turning radius (0°) is represented by point  146 . 
     Yaw reactions of the track assemblies are resisted by the steerable structures  40 . The steerable structures  40  and linkage on each articulating beam  50  axle provide Ackermann steering geometry. As the utility vehicle  20  is steered, the steerable structures  40  on the inside and outside of each articulating beam  50  axle are controlled via simple unequal parallelogram linkage  148  as shown in  FIG. 8  and the speed of the inside wheel/tires or track motors  104  are reduced to the proper speed for the steer angle (reacting in a manner similar to that for automotive stability/traction control—see included equations below) of the front (or the rear for center-axis AWS) kingpin  112  best seen in  FIGS. 5A and 5B . Examples of the utility vehicle  20  provide a provision to reduce the vehicle turning radius to less than that of the following example by further reduction of the speed of the inside wheel/tire or motors  104 , as dictated by the below equations. This is accomplished by continuing to turn the steering wheel or steering input device in the direction of the turn to create a signal to reduce the speed of the motors  104  on the inside of the turn (essentially dynamic braking). The speed reduction is limited to a pre-established value (above “0” mph) to maintain traction, minimize terrain deformation and to enhance control. 
     In one example, the utility vehicle  20  includes Ackermann steering geometry provided at each beam axle by unequal parallelogram linkage that can be manually or power (electric or hydraulic) activated or controlled via wired or fluid power means. 
     In another example of the utility vehicle  20  described above, the utility vehicle  20  includes no understeer or over-steer due to all-wheel-steering and Ackermann steering geometry, and no spinning or slipping during turns due to accurate motor speed control provided by synchro-steer technology as described in patents such as U.S. Pat. Nos. 7,992,659, 7,914,022, 8,474,841, and related patents, for example. 
     In another example, the utility vehicle  20  includes synchro-steer technology to control the speed of the steered wheel/tires or tracks based on the steer angle of one of the kingpins  112  (best seen in  FIGS. 5A and 5B , and to provide a further speed reduction of the inside wheel/tires or tracks to decrease the utility vehicle  20  turning radius. 
       FIG. 9  shows the utility vehicle  20  providing 8- to 10-foot circle turning radii without the speed restriction of the inside wheel/tires or tracks, and the inside wheel/tire or track speed reduction reduces the circle to 4-feet or less, compared to other vehicles shown. 
     Equations for Ackermann Steering (two-wheel steering) using Synchro-Steer Technology referring to  FIG. 10A : 
         T   Ri =tan(90°−α)* y−o   rear    Equation 1:
 
         T   Ro   =T   Ri   +x    Equation 2:
 
         r   i =SQRT[ y   2 +( T   Ri   +o   rear ) 2 ]− o   front    Equation 3:
 
         r   o =SQRT[ y   2 +( T   Ro   −o   rear ) 2 ]+ o   front    Equation 4:
 
       ω=90°−tan −1 [( T   Ro   −o   front )/ y]   Equation 5:
 
       Axel Ratio= T   Ro   /T   Ri    Equation 6:
 
       α u-turn =90°−tan −1 ( o   rear   /y]   Equation 7:
 
       α zero-turn =90°−tan −1 [(− x/ 2+ o   rear )/ y]   Equation 8:
 
       MPH inside =Outside Wheel Speed/Axle Ratio   Equation 9:
 
       MPH outside =Full FWD −[(Full FWD /2)/(α zero-turn −α slowdown )*(α current −α slowdown )]  Equation 10:
 
       MPH outside =Half FWD −[(Half FWD /2)/(α zero-turn −α slowdown )*(α current −α slowdown )]  Equation 11:
 
       MPH outside =Full REV −[(Full REV /2)/(α zero-turn −α slowdown )*(α current −α slowdown )]  Equation 12:
 
       MPH outside =Half REV −[(Half REV /2)/(α zero-turn −α slowdown )*(α current −α slowdown )]  Equation 13:
 
       MPH front inside =( r   i   /T   Ro )*MPH rear outside    Equation 14:
 
       MPH front outside =( r   o   /T   Ro )*MPH rear outside    Equation 15:
 
     Equations for Ackerman Steering (four-wheel steering) using Synchro-Steer Technology referring to  FIG. 10B : 
       MPH front inside =MPH rear inside =( r   i   /r   o )*MPH front or rear outside    Equation 16:
 
       MPH front outside =MPH rear outside =( r   o   /r   i )*MPH rear or front inside    Equation 17:
 
         r   i   =T   Ri =tan(90°−α)* Y−O   rear    Equation 18:
 
       sin(α)=( Y/ 2)/ r   i    Equation 19:
 
         r   o   =T   Ro   =T   ri   +X=r   i   +X    Equation 20:
 
       sin(ω)=( Y/ 2)/( r   i   +X )=( Y/ 2)/ T   Ro    Equation 21:
 
     Where: X is the track width, Y is the wheelbase, O is the wheel offset, α is the steer angle on the inside ground engaging member(s), ω is the steer angle on the outside ground engaging member(s), r i  is the turn radius on the front inside ground engaging member, r o  is the turn radius on the front inside ground engaging member, T Ri  is the turn radius of the rear inside ground engaging member, T Ro  is the turn radius of the rear outside ground engaging member, MPH inside  is the wheel speed on the inside ground engaging member, and MPH outside  is the wheel speed on the outside ground engaging member. 
     Other benefits derived from the All-Wheel Drive (AWD) and All-Wheel Steering (AWS) features include: minimization of the steer angles required to negotiate turns, thereby reducing the axial loading at the wheel/tires or tracks. AWS allows the front or rear axles to be controlled independently, thereby allowing front wheel or rear wheel steering. AWS allows steering at each kingpin  112  to be individually controlled, thereby enabling “crab-steering” and zero-turn maneuvers. 
     In another example of the utility vehicle  20  described above, the utility vehicle  20  exhibits a highly stable platform due to its relatively large base (wide track and long wheelbase) and AWS. In another example, the utility vehicle  20  includes relatively high traction due to AWD and large contact areas provided by the pneumatic wheel/tires, non-pneumatic wheel/tires, or track assemblies. 
     The utility vehicle  20  can include embodiments that are supported via pneumatic or non-pneumatic tires of a wheel assembly or corresponding track assemblies, and the utility vehicle  20  may or may not integrate axles and suspension elements. Steering control of the proposed utility vehicle can be provided by wheel/tires on front/rear located axles or suspension elements (generally Ackermann geometry driven by transaxles incorporating lockable differentials), by all wheel steering via wheel/tires on all axles or suspension elements (these can incorporate transaxles or individual wheel motors), or by machine articulation (generally driven by transaxles incorporating lockable differentials). 
     Traction drive is provided in numerous configurations of the utility vehicle  20  with mechanical power supplied by spark-ignition or compression-ignition engines or electric power provided by stored energy devices. Variations can include mechanical transmissions, continuously variable transmissions (CVT), hydrostatic pumps, electric drives, and hybrids. 
     The example utility vehicle  20  shown in  FIG. 1  can also include a frame constructed of buoyant tubular members, an occupant protection system (OPS), bench or bucket seating, highly efficient electric generator/alternators, controllers and electric motors powered by stored-energy or hybrid power generation devices (with spark- or compression-ignition engines), service and park brake systems, a steering system that controls the speed and direction of the steerable wheels or tracks based on steer-angle input, and a speed/directional control system (linkage or system module with wire harness), and a suspension system. 
     In another embodiment of the utility vehicle  20  described above, the utility vehicle  20  includes an amphibious capability due to the compartmental structures surrounding the operator and passenger and separately for the hybrid and other power generation devices providing the buoyancy necessary for machine floatation. 
     Example utility vehicle configuration:
     Length
       90-in (end of tracks), wheelbase=76-in   
       Width
       63-in at wheel/track edges (72-in with extensions), track=52-in (61-in with tracks)   
       Height
       64-in (top of OPS)   
       Ground clearance
       10-in @ center of tunnel area   
       Weight (curb)
       1,100 lb (base configuration)   1,900 lb (operator, passenger, cargo)   
       Fuel capacity
       7 gallons (U.S.) gasoline or diesel, 33 lb LPG   
       G.V.W.
       2,200 lb   
       Tow Capacity
       1,500/200 lb   
       Cargo box
       Standard configuration (24-in L×48-in W×10-in H)   350 lb load (maximum)   
       Battery—Starting
       360 CCA type U1   
       Electrical system
       12 VDC with negative ground   
       

     OPS Enclosure 
     
         
         
           
             Includes gull-wing entry/egress doors and designated steps 
             Two seats for 5 th  percentile-95 th  percentile male occupants
           High-back bucket seats for two 215 lb occupants   
         
             Operator Protection System
           OPS complies with SAE J2258 and ANSI B71.9   3-point occupant restraints comply with SAE J2258 and ANSI B71.9   
         
             12 VDC power outlet 
             inside mirror 
             cup-holder 
             Optional full weather cab 
             Optional work lights 
           
         
       
    
     Engine 
     
         
         
           
             SI Engine—55 kW (72 hp) @6200 rpm 
             SI Engine—29.9 kW (40 hp) @3600 rpm 
             CI Engine—42 kW (56 hp) @2600 rpm (DI), 
             Dual element remote located air filtration 
             Single exhaust (with after-treatment)
           EPA P-3 &amp; CARB T-IV Final compliant   
         
             Sound power 80 dbA 
             EMC compliant to Directive 97/24/EC Chapter 8 
           
         
       
    
     Electric or Hydrostatic Traction Drive 
     
         
         Acceleration
       19 mph in 6 sec   
     
         Maximum speed
       45 mph on 0% grade   20 mph on 20% grade   5 mph on 35 degree grade   
     
         Drawbar pull
       1500 lb @5 mph   
     
         Traction drive system electric or hydrostatic
       40-45 kW generation at 430 VDC   20-22 kW generation at 240 VAC   Tandem 16 cc/rev pump   Four 5-6 kW 1-phase 240 VAC motors, 5-lug 4.5″ B.C., +/−0 to 500 RPM   Four 140 cc/rev generator motors, 5-lug 4.5″ B.C. +/−0 to 500 RPM   
     
         Directional control
       Treadle-type with separate foot pedal controls for Forward and Reverse   
     
         Speed control
       Foot pedal controls effective gear ratio of traction drive   SEVCON controllers   
     
         Braking
       Service—regenerative and mechanical friction   Parking—positive locking   
     
       
    
     Track &amp; Suspension 
     
         
         Tracks (5-lug 4.5″ B.C.)
       11 in″ wide   Contact area=11 in×20 in×4=880 in 2      Ground pressure=1900 lb/880 in 2 =2.16 lb/in 2      Construction/material—rubber with steel and polyester cord reinforcement
           Inside Rubber ASTM D2000 2AA 914 (Duro, Shore A: 90±5)   Fabric   Steel Cord   Structural Rubber ASTM 02000 2AA 614 (Duro, Shore A: 60±5)   Fabric   Outside Rubber ASTM 02000 2AA 614 (Duro, Shore A: 65±5)   
           
     
         Track suspension
       Articulating axles front and rear, extension feature adds 12″ width   Adjustable-rate coil-spring-over-shock suspensions/track
           optional adjustable-rate air-springs   
           
     
       
    
     Steering 
     
         
         
           
             All Wheel steering coupled to Synchro-Steer 
             Steering wheel directional control—Left turn (CCW) &amp; Right turn (CW)
           Input to Synchro-Steer to control individual track speed &amp; direction   All Wheel Steer angle for turns up to 5-ft radius   Synchro-Steer integrated for turns to 2-ft radius
 
For 60″ inside radius with 52″ track and 76″ wheelbase
   
         
           
         
         inside steer angle=33.4 deg 
         outside steer angle=17.6 deg 
       
    
     While this disclosure has been written in conjunction with the specific embodiments described above, it is evident that many alternatives, combinations, modifications and variations are apparent to those skilled in the art. Accordingly, the described embodiments of this disclosure, as set forth above are intended to be illustrative only, and not in a limiting sense. Various changes can be made without departing from the spirit and scope of this disclosure. Combinations of the above embodiments and other embodiments will be apparent to those of skill in the art upon studying the above description and are intended to be embraced therein. Therefore, the scope of the present disclosure is defined by the appended claims, and all devices, processes, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.