Patent Publication Number: US-2023163512-A1

Title: Conductive linkage for work machine having multiple degrees of freedom

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/535,235, entitled “Terminal Assembly for Conductor Rod Having Multiple Degrees of Freedom,” filed Nov. 24, 2021, which is expressly incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a conductive rod and connector for conveying electrical power to a moving vehicle. More specifically, the present disclosure relates to a conductive rod with a terminal assembly having multiple degrees of freedom, and to an electrically powered work machine coupled to a roadside power source via the conductive rod and terminal assembly. 
     BACKGROUND 
     Heavy work machines, such as earth-moving vehicles or hauling trucks, require significant power to carry out their functions. The machines themselves can be of substantial weight, and their loads require large amounts of power to move. Diesel engines typically provide that power, but they can have disadvantages. For instance, in some implementations, heavy work machines may need to travel large distances through rugged terrain. At a remote mining site, for example, groups of these machines are often employed to ferry extreme loads along roadways, or haul routes, extending between various locations within the mining site. Supplies of diesel fuel may be far away from such locations or not easily delivered to such locations. In addition, the groups of diesel machines can generate significant pollution. 
     Electrical power has been used to supplement these diesel engines while the work machines move. In some environments, the electrical power is delivered from wires over the haul route to a pantograph on the work machine as the machine travels the haul route, as in a cable car. But overhead wires cannot reliably provide sufficient electrical energy to power a heavy work machine during long movements. Nor can the overhead delivery provide enough current to charge backup batteries for an electric machine at the same time. As a result, electrical power through overhead wires typically supplements, rather than replaces, diesel engines in heavy work machines. In other environments, on the other hand, a power rail based on the ground may provide electrical power to heavy work machines. Maintaining an electrical connection with a power rail while a heavy work machine moves can be challenging, however. In locations such as a mining site, the haul route may be uneven, hilly, and pocked. These variations may lead to irregular movements by the machine or unexpected changes in position by the power rail, causing the machine to disconnect from the rail. Steering deviations for the heavy work machine could also disrupt the connection of the machine with the power rail, detracting from the value of rail-based delivery of electrical power. 
     One approach for providing electrical power to a work machine while traveling on a roadway is described in International Patent App. Pub. No. WO 2020/186296A1 (“the &#39;296 application”). The &#39;296 application describes an electrical delivery system at a mine site where two or more conductors extend along a roadside, a contact assembly maintains electrical connection with the roadside conductors, and an electric current collector carries electrical power from the contacts to a moving vehicle. The electric current collector includes an arm that is retractable to the vehicle and includes one or more rigid mechanical linkages. The linkages, however, are in the form of single-arm or double-arm pantographs that purportedly allow for lateral pivoting movement while maintaining a parallel connection between the vehicle and the contact assembly. The &#39;296 application does not contemplate more diverse movements that may arise between a vehicle and roadside conductors. As a result, the system of the &#39;296 application is not desirable for heavy work machines operating in environments in which the relative positions of the vehicle and the roadside conductors may change in multiple dimensions. 
     Examples of the present disclosure are directed to overcoming deficiencies of such systems. 
     SUMMARY 
     In an aspect of the present disclosure, a conductive linkage for powering a work machine includes a contactor having an interface configured to slidingly engage along a rail surface of at least one power rail along a haul route, a first trailing arm having a first upper end and a first lower end, and a second trailing arm having a second upper end and second lower end. The second trailing arm is substantially parallel to the first trailing arm. The linkage includes a first lower joint positioned between the first lower end and the contactor, where the first lower joint has a first axis of rotation substantially parallel to the interface and a second axis of rotation substantially orthogonal to the first axis of rotation. The first trailing arm is configured to pivot with respect to the rail surface vertically about the first axis of rotation and laterally about the second axis of rotation. The linkage also includes a second lower joint positioned between the second lower end and the contactor, where the second lower joint has the first axis of rotation and a third axis of rotation substantially orthogonal to the first axis of rotation. The second trailing arm is configured to pivot with respect to the rail surface vertically about the first axis of rotation and laterally about the third axis of rotation, while the first trailing arm and the second trailing arm conduct electrical power to the work machine. 
     In another aspect of the present disclosure, a work machine includes an electric engine, traction devices configured to cause movement of the work machine along a haul route when powered by the electric engine, a conductor rod configured to receive electrical energy for the work machine during the movement of the work machine, and a conductive linkage connected to the conductor rod and configured to conduct the electrical energy to the conductive rod from at least one power rail along the haul route. The conductive linkage includes a current collector having an interface configured to movably engage with a surface of at least one power rail along the haul route and trailing arms between the conductor rod and the current collector. The trailing arms are substantially parallel to each other and have upper ends and lower ends. Lower joints respectively attach the lower ends to the current collector and have lower axes of rotation including a first axis of rotation substantially parallel to the interface and at least one other axis of rotation substantially orthogonal to the first axis of rotation. Upper joints respectively attach the upper ends to the conductor rod and have upper axes of rotation substantially parallel to corresponding ones of the lower axes of rotation. The lower joints and the upper joints are configured to enable the trailing arms to move laterally and vertically with respect to the surface of the at least one power rail in response to the movement of the work machine. 
     In yet another aspect of the present disclosure, a method for conducting electrical power to a work machine from at least one power rail includes establishing a connection between an electrically conductive assembly associated with the work machine and a rail surface of the at least one power rail, where the electrically conductive assembly has trailing arms and a current collector. The trailing arms are substantially parallel to each other and have upper ends and lower ends with the lower ends being attached via corresponding lower joints to the current collector. The method includes causing the electrically conductive assembly to move the current collector across the rail surface and conducting the electrical power from the current collector and through the trailing arms. In addition, the method includes enabling one or more of horizontal rotation and vertical rotation of the trailing arms, with respect to the rail surface, about the corresponding lower joints in the current collector, and maintaining the connection during the one or more of the horizontal rotation and the vertical rotation of the trailing arms. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is an isometric view of an electrically powered work machine coupled to a roadside power source via a conductive rod, connector, and trailing arms in accordance with an example of the present disclosure. 
         FIG.  2    is a partial isometric rear view of a conductive rod, first connector, and trailing arms in accordance with an example of the present disclosure. 
         FIG.  3    is longitudinal section of the conductive rod, connector, and trailing arms of  FIG.  2    in accordance with an example of the present disclosure. 
         FIG.  4    is cross section of the conductive rod, connector, and trailing arms of  FIG.  2    in accordance with an example of the present disclosure 
         FIG.  5    is a partial isometric rear view of a conductive rod and second connector in accordance with an example of the present disclosure 
         FIG.  6    is an isometric view of a longitudinal section of the conductive rod and connector of  FIG.  5    in accordance with an example of the present disclosure. 
         FIG.  7    is a partial isometric rear view of a conductive rod and second connector with an insulative cap removed in accordance with an example of the present disclosure. 
         FIG.  8    is a flowchart depicting a method of providing electrical power to a work machine during movement in accordance with an example of the present disclosure. 
         FIG.  9    is a flowchart depicting another method of providing electrical power to a work machine during movement in accordance with an example of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts.  FIG.  1    illustrates an isometric view of a work machine  100  within an XYZ coordinate system as one example suitable for carrying out the principles discussed in the present disclosure. Exemplary work machine  100  travels along a defined path or roadway, also termed haul route  101 , typically from a source to a destination within a worksite. In one implementation as illustrated, work machine  100  is a hauling machine that carries a load within or from a worksite within a mining operation. For instance, work machine  100  may haul excavated ore or other earthen materials from an excavation area along haul route  101  to dump sites and then return to the excavation area. In this arrangement, work machine  100  may be one of many similar machines configured to ferry earthen material in a trolley arrangement. While illustrated as a large mining truck in this instance, work machine  100  may be any machine that carries a load between different locations within a worksite, examples of which include an articulated truck, an off-highway truck, an on-highway dump truck, a wheel tractor scraper, or any other similar machine. Alternatively, work machine  100  may be an off-highway truck, on-highway truck, a dump truck, an articulated truck, a loader, an excavator, a pipe layer, or a motor grader. In other implementations, work machine  100  need not haul a load and may be any movable machine associated with various industrial applications including, but not limited to, mining, agriculture, forestry, construction, and other industrial applications. 
     Referring to  FIG.  1   , and relevant to the present disclosure, an example work machine  100  includes a frame  103  powered by electric engine  102  to cause rotation of traction devices  104 . Traction devices  104  are typically four or more wheels with tires, although tracks or other mechanisms for engagement with the ground along haul route  101  are possible. Electric engine  102  functions to provide mechanical energy to work machine  100  based on an external electrical power source, such as described in further detail below. A primary example of mechanical energy provided by electric engine  102  is propelling traction devices  104  to cause movement of work machine  100  along haul route  101 , but electric engine  102  also includes components sufficient to power other affiliated operations within work machine  100 . For instance, in some implementations, electric engine  102  includes equipment for converting electrical energy to provide pneumatic or hydraulic actions within work machine  100 . While electric engine  102  is configured to operate from an external electrical power source, electric engine  102  typically includes one or more batteries for storing electrical energy for auxiliary or backup operations. 
     In accordance with the principles of the present disclosure, work machine  100  further includes a conductor rod  106  configured to receive electrical power from a power rail  108 . In some examples, power rail  108  includes one or more beams of metal arranged substantially parallel to and a distance above the ground. Support mechanisms hold power rail  108  in place along a distance at the side of a haul route  101  for work machine  100  to traverse. The support mechanisms and power rail  108  may be modular in construction, enabling their disassembly and reassembly at different locations or their repositioning along the existing haul route  101 . Moreover, while shown in  FIG.  1    to the left of work machine  100  (along the Y axis) as work machine  100  travels in the direction of the X axis, power rail  108  may be installed to the right of work machine  100  (along the −Y axis) or in other locations suitable to the particular implementation. In many examples, such as within a mining site, power rail  108  will not be configured continuously at a fixed distance along a side of haul route  101  and at a fixed height above the ground due, at least in part, to the variation of the terrain. Therefore, it is expected that the vertical, horizontal, and angular positions of the surface of power rail  108  in the XYZ planes will vary along haul route  101 . 
     Power rail  108  provides a source of electrical power for work machine  100  as either AC or DC voltage. In some examples, power rail  108  has two or more conductors, each providing voltage and current at a different electrical pole. In one implementation (e.g., an implementation in which the power rail  108  includes three conductors), one conductor provides positive DC voltage, a second conductor provides negative DC voltage, and a third conductor provides a reference voltage of 0 volts, with the two powered conductors providing +1500 VDC and −1500 VDC. These values are exemplary, and other physical and electrical configurations for power rail  108  are available and within the knowledge of those of ordinary skill in the art. 
     Conductor rod  106  enables electrical connection between work machine  100  and power rail  108 , including during movement of work machine  100  along haul route  101 . In the example shown in  FIG.  1   , conductor rod  106  is an elongated arm resembling a rigid pole.  FIG.  1    shows conductor rod  106  positioned along a front side of work machine  100 , with respect to the direction of travel of work machine  100  in the direction of the X axis. In this arrangement, conductor rod  106  is located in  FIG.  1    in the Y-Z plane essentially along the Y axis with a proximal end near a right side of work machine  100  and a distal end at a left side of work machine  100 . Conductor rod  106  may be attached to any convenient location within work machine  100 , such as to frame  103 , in a manner to enable conductor rod  106  to reach and couple to power rail  108 . Shown in  FIG.  1    as extending to a left side of work machine  100  toward power rail  108 , conductor rod  106  may alternatively be arranged to extend to a right side (along the −Y axis) and at any desired angle from work machine  100  such that conductor rod  106  may be coupled to power rail  108  for obtaining electrical power. 
     As embodied in  FIG.  1   , conductor rod  106  includes a cylinder portion  109  mounted to frame  103  of work machine  100 . Cylinder portion  109  has a hollow interior and may be a conductive metal having suitable mechanical strength and resiliency, such as aluminum. Within cylinder portion  109 , an extension  110  is retained. Extension  110  is slidably engaged within cylinder portion  109  of conductor rod  106  such that it may be extended or retracted axially, i.e., along the Y axis in  FIG.  1   , to adjust the reach of conductor rod  106 . Specifically, in a retracted position, extension  110  is caused to slide within cylinder portion  109  of conductor rod  106  such that a length of conductor rod  106  roughly spans the width of work machine  100 . A junction  112  serves as the interface between extension  110  and cylinder portion  109 , which is the main body of conductor rod  106 . When extension  110  is fully retracted or collapsed into cylinder portion  109 , junction  112  essentially becomes the left edge of conductor rod  106 . On the other hand, when extension  110  is extended from cylinder portion  109  of conductor rod  106 , extension  110  may reach from work machine  100  to above or near power rail  108  on the side of haul route  101 . 
     Within, and possibly including cylinder portion  109 , conductor rod  106  has a series of electrical conductors passing longitudinally, i.e. along the Y axis in  FIG.  1   , at least from a base  122  at a proximal end to a tip  124  at a distal end. Typically, the conductors within conductor rod  106  are formed of a metallic material. Moreover, as with cylinder portion  109 , the material for conductors within conductor rod  106  typically have suitable mechanical strength and resiliency to permit their stable extension from work machine  100  to above power rail  108  at the side of haul route  101 . In some examples, the conductors are concentric tubes, or hollow cylinders, of solid metal such as aluminum nested together and sized to provide electrical capacity sufficient for powering work machine  100 . Tubular conductors within extension  110  slidably engage with corresponding tubular conductors in the portion of conductor rod  106  mounted on work machine  100 . This engagement while the tubes slide ensures electrical continuity during extension or retraction of conductor rod  106 . 
     At a distal end of extension  110  at tip  124  within conductor rod  106 , a connector assembly  114  provides an interface to power rail  108  via trailing arms  116  and contactor  118 . The arrangement of connector assembly  114 , trailing arms  116 , and contactor  118  of  FIG.  1   , which are collectively also referred to as a terminal assembly, are described in further detail in  FIGS.  2 - 4   . Power rail  108  is typically arranged along a side of haul route  101 , and work machine  100  traverses haul route  101  substantially in parallel with power rail  108 . Thus, in reference to  FIG.  1   , power rails  108  and a travel path for work machine  100  are substantially in parallel with each other and with the X axis. Contactor  118  is configured to maintain an electrical connection with power rail  108  while sliding along its surface in the direction of the X axis as work machine  100  moves. In some examples, trailing arms  116  are conductors coupled to contactor  118 , each conducting voltage and current at a different electrical pole for respective conductors within conductor rod  106 . In operation, electrical power is accessed from power rail  108  via contactor  118 , which remains in contact during movement of work machine  100 , and the electrical power is conducted through trailing arms  116  into connector assembly  114 . 
     From connector assembly  114 , the electrical power is conveyed at tip  124  through the nested tubular conductors within extension  110  and cylinder portion  109  to head  122  of conductor rod  106  and through a head-end interface  120  to work machine  100 . Head-end interface  120  provides at least an electrical connection between conductor rod  106  and work machine  100  for powering electric engine  102  and otherwise enabling operations within work machine  100 . In some examples, head-end interface  120  may also provide an interface for controls between work machine  100  and conductor rod  106 . In some examples, head-end interface  120  includes passageways to control mechanical operation of conductor rod  106 , such as for pressurized air of a pneumatic control system to extend and retract extension  110 . In other examples, head-end interface  120  includes passageways for signals to communicate with electronic controls. 
     Connector assembly  114  not only provides electrical connection between the conductors within extension  110  of conductor rod  106  and trailing arms  116 , but also accommodates the various changes in relative position between power rail  108  and work machine  100  during travel along haul route  101 . Those changes in relative position can include multiple deviations, such as those occurring laterally (work machine  100  and connector assembly  114  moving in the Y axis relative to contactor  118 ), vertically (work machine  100  and connector assembly  114  moving in the Z axis relative to contactor  118 ), and angularly (work machine  100  and connector assembly  114  moving in the X-Y plane angularly around the Z axis). One or all of these deviations could occur as a driver steers work machine  100  along haul route  101 , work machine  100  responds to an uneven or pocked roadway, or an orientation of power rail  108  varies with respect to work machine  100 .  FIGS.  2 - 4    are discussed collectively below and illustrate details of an example terminal assembly  200  suitable for accommodating multiple deviations in position between work machine  100  and contactor  118 . 
       FIG.  2    is a view from a side of power rail  108  opposite work machine  100  facing generally forward (i.e., along the X axis), which shows a terminal assembly  200  from a back side of extension  110 . As shown in  FIG.  2   , power rail  108  contains three conductors. In one example, two of the conductors provide electrical power at different polarities while the third conductor provides a reference of 0 volts. In other examples, the conductors can provide AC voltage at three different polarities or power rail  108  and conductor rod  106  can contain fewer or more than three conductors. Contactor  118  is electrically coupled to power rail  108  and slides along its surface to maintain an electrical connection. In some implementations, contactor  118  may be latched or slidably interlocked into power rail  108  rather than having a connection on the upper surface of power rail  108 . Ultimately, for purposes of the present disclosure, contactor  118  provides an interface between the respective conductors of power rail  108  and trailing arms  116 . As shown in  FIG.  2   , connector assembly  114  within terminal assembly  200  is integrated into a distal end of extension  110 . A rotational interface  202  of connector assembly  114  exits a bottom portion of extension  110  and culminates in first lug  204 , third lug  206 , and second lug  208 . First lug  204 , third lug  206 , and second lug  208  respectively attach through connector assembly  114  to corresponding conductors within extension  110  and provide a separate conductive path between those conductors and contactor  118 . 
     While  FIG.  2    shows an external view of terminal assembly  200 ,  FIGS.  3  and  4    illustrate different sectional views.  FIG.  3   , which is a longitudinal section of a portion of terminal assembly  200 , reveals an arrangement of nested concentric conductors within extension  110 . In this example, first conductor  302  is positioned at an axial center of extension  110  along the Y axis and is surrounded concentrically by second conductor  304 . Further, third conductor  306  surrounds second conductor  304 . At least second conductor  304  and third conductor  306  are tubes, meaning they are substantially cylindrical and hollow in form having an outer surface and an inner surface surrounding a central longitudinal axis. As shown, first conductor  302 , second conductor  304 , and third conductor  306  are formed of conductive material, typically aluminum, or a similar metal or alloy with high electrical conductivity and mechanical strength. An outer covering or sheath of extension  110  surrounds third conductor  306 . Depending on the implementation, regions between the concentric conductors may be partially or completely filled with insulative material, other substance, or air. First conductor  302 , second conductor  304 , and third conductor  306  provide part of a path for conducting the electrical power from power rail  108  to work machine  100 . 
     Connector assembly  114  includes a series of orthogonal conductors positioned to intersect with first conductor  302 , second conductor  304 , and third conductor  306 , respectively. With respect to first conductor  302 , a first pin  308  extends laterally through extension  110  along an axis A-A ( FIGS.  3  and  4   ), substantially along the Z axis. In some examples, first pin  308  is a longitudinal piece of metal, such as aluminum, resembling a dowel or a pin that may be solid or hollow. First pin  308  is configured to pass through extension  110  transversely or radially with respect to a longitudinal axis of extension  110  and at a length that it substantially traverses the diameter of extension  110 . Second conductor  304  has an opening  309 , and third conductor  306  has an opening  311  that each provides clearance for first pin  308  to pass through extension  110  without contacting those conductors ( FIG.  4   ). First conductor  302  has a passageway  313  for receiving and contacting first pin  308 . Within opening  309 , first pin  308  freely rotates around axis A-A while maintaining an electrical coupling between first pin  308  and first conductor  302 . In some examples, to assist with both the rotation and the coupling, a liquid metal such as Galinstan may be added to the joint within opening  309 . Accordingly, first pin  308  extends substantially perpendicular to first conductor  302 , starting from a rotational interface  202  at an exterior of extension  110  and passing substantially through a diameter of extension  110 . A cap  324  of insulative material such as plastic seals the region surrounding the top of first pin  308 . Separator  312  surrounds and insulates first pin  308  within rotational interface  202 . 
     In the example illustrated in  FIG.  3   , first lug  204  intersects with a lower portion of first pin  308  within rotational interface  202 . In some examples, the intersection is a threaded and tight fit engagement. As illustrated in  FIG.  3   , first lug  204  intersects with first pin  308  substantially at a right angle, such that first lug  204  aligns with an axis B-B that may be parallel to a longitudinal axis of extension  110  (shown as the Y axis in the figures). A first shaft  310  mates with a socket joint within first lug  204  and provides rotational movement within the socket about the axis B-B. While first shaft  310  is shown as being rotatable about axis B-B with a socket of first lug  204 , other mechanisms for permitting movement of first shaft  310  are feasible. For instance, a ball-and-socket joint could achieve similar results. At an opposite end of first shaft  310  from the socket joint, first shaft  310  attaches to first arm  210  through a first hinge  320 . First hinge  320  enables first arm  210  to rotate around an axis D-D extending through first arm  210 , as shown in  FIG.  2   . 
     At its opposite end, first arm  210  connects to a similar configuration within contactor  118 . In some examples, the components within  118  associated with trailing arms  116  have axes of rotation parallel to those within contactor assembly  114 , such as around axes B-B, C-C, D-D, E-E, and F-F, but the additional axes within contactor assembly  114  are not shown on  FIG.  2    for simplicity. Namely, in some examples, contactor  118  includes a first contactor hinge  216  and first contactor lug  218 . Connected with first arm  210 , first contactor hinge  216  provides rotation about an axis parallel to axis D-D. First contactor lug  218  enables rotation about an axis through its center, which in some examples is parallel to axis B-B in  FIG.  3   . Mechanically, first contactor lug  218 , first contactor hinge  216 , first arm  210 , first hinge  320 , first shaft  310 , first lug  204 , and first pin  308  enable flexible and versatile movement through the combined movement of the joints between first conductor  302  and contactor  118 . Electrically, the connections of these components provide a path for the conduction of electrical power from one of the conductors in power rail  108  to first conductor  302  within extension  110 . 
     Similarly, connector assembly  114  in some examples includes another conductive path extending from contactor  118  to second conductor  304 . Referring to  FIG.  4   , second pin  318  is tubular in shape and is situated orthogonally to second conductor  304  and concentrically around axis A-A. Second pin  318  contacts second conductor  304  and may freely rotate about axis A-A, providing electrical conductivity between second conductor  304  and second lug  208 , which is connected at the portion of second conductor  304  within rotational interface  202 . Second lug  208  is positioned angularly to first lug  204 , which in the example illustrated is substantially a right angle. Accordingly, second lug  208  and second shaft  402 , which are coupled through a rotational joint, are aligned along an axis C-C. In some examples, as in  FIG.  2   , axis A-A, axis B-B, and axis C-C are perpendicular to each other. Second lug  208  with second shaft  402  attaches to second arm  214  through a second hinge  404 . Second hinge  404  enables rotation of second arm  214  around an axis E-E, which may be substantially perpendicular to axis D-D. Finally, second arm  214  extends to contactor  118  where it is connected via a second contactor hinge  224  and a second contactor lug  226 . Second contactor hinge  224  is configured to rotate around an axis substantially parallel to axis E-E. Second contactor hinge  224  is connected through a rotational socket to second contactor lug  226 , which is configured to rotate around an axis through its center. In some examples, that rotational axis for second contactor lug  226  is parallel to axis C-C. Electrically, the connections of second contactor lug  226 , second contactor hinge  224 , second arm  214 , second hinge  404 , second lug  208 , and second pin  318  provide a path for the conduction of electrical power from a second conductor in power rail  108  to second conductor  304  within extension  110 . 
     Referring again to  FIG.  3   , a third pin  314  extends laterally through extension  110  and concentrically around axis A-A. In some examples, third pin  314  is tubular in shape and connects with third conductor  306 . As part of rotational interface  202 , third pin  314  freely rotates around axis A-A while maintaining an electrical coupling with third conductor  306 . Accordingly, third pin  314  substantially forms a right angle with third conductor  306  and is in parallel with first pin  308 . Within rotational interface  202 , third pin  314  on one side includes an opening for the passage of first lug  204  and, on an opposite side, is connected to third lug  206 . In the implementation in  FIG.  3   , third lug  206  intersects with third pin  314  substantially at a right angle, such that third lug  206  is aligned with first lug  204  along axis B-B. A third shaft  316  mates with a socket joint within third lug  206  and provides rotational movement within the socket around the axis B-B. As with first lug  204  and first shaft  310 , other mechanisms for enabling rotation of third shaft  316  around axis B-B may be employed besides a socket joint. 
     At an opposite end of third shaft  316  from the socket joint, third shaft  316  attaches to third arm  212  through a third hinge  322 . Third hinge  322  enables third arm  212  to rotate around an axis F-F extending through third arm  212  as shown in  FIG.  2   . Third arm  212  is also attached to contactor  118  at its distal end via a third contactor hinge  220 . Similar to first contactor hinge  216 , third contactor hinge  220  enables rotation of third arm  212  around an axis parallel to axis F-F. Third contactor hinge  220  is connected through a rotational socket to third contactor lug  222 , which enables rotation around an axis through its center. Electrically, the connections of third contactor lug  222 , third contactor hinge  220 , third arm  212 , third hinge  322 , third shaft  316 , third lug  206 , and third pin  314  provide a path for the conduction of electrical power from another of the conductors in power rail  108  to third conductor  306  within extension  110 . 
     Overall, as shown in  FIGS.  2 - 4   , terminal assembly  200  with connector assembly  114  and contactor  118  provide an apparatus configured to have the ability to move in multiple dimensions. Collectively, the various joints within connector assembly  114 , and to some extent also within contactor  118 , provide multiple degrees of freedom for extension  110  to move relative to contactor  118 . As work machine  100  moves forward (in the direction of the X axis), trailing arms  116  and contactor  118  trail behind extension  110 . If the position of extension  110  changes with respect to the position of contactor  118 , connector assembly  114  permits trailing arms  116  to move in several directions and maintain the connection between contactor  118  and power rail  108 . Specifically, to accommodate minor lateral displacement (work machine  100  and connector assembly  114  moving in a direction substantially parallel to the Y axis relative to contactor  118 ), first hinge  320 , second hinge  404 , third hinge  322  in connector assembly  114  and, for some examples first contactor hinge  216 , second contactor hinge  224 , and third contactor hinge  220  in contactor  118 , all permit rotation around axes that allow lateral movement without imparting stress on contactor  118  that might lead to detachment from power rail  108 . For vertical displacement (work machine  100  and connector assembly  114  moving in a direction substantially parallel to the Z axis relative to contactor  118 ), first shaft  310 , second shaft  402 , and third shaft  316  in connector assembly  114  and, for some examples first contactor lug  218 , second contactor lug  226 , and third contactor lug  222  in contactor  118 , all permit rotation around axes that allow vertical movement without imparting stress on contactor  118  that might lead to detachment from power rail  108 . Namely, these axes for vertical displacement are axis B-B and axis E-E. And for angular displacement (work machine  100  and connector assembly  114  moving in the X-Y plane angularly around the Z axis), rotational interface  202  within connector assembly  114  is configured to enable rotation around axis A-A, which together with rotation around others of the joints discussed, permits minor angular movement of extension  110  with respect to power rail  108  without causing detachment of contactor  118  and interruption of the electrical conduction to work machine  100 . 
     While  FIGS.  2 - 4    illustrate a first example of connector assembly  114 ,  FIGS.  5 - 7    depict a second example of a connector assembly  500  including a connection assembly for use with work machine  100 . As with connector assembly  114 , second connector  502  includes structural features for accommodating multiple deviations in position between work machine  100  and contactor  118 .  FIG.  5    is a view from an end of conductor rod  106  facing forward, which shows a back side of extension  110  with respect to a direction of forward travel of work machine  100  (along the X axis). As shown in  FIG.  5   , second connector  502  is positioned at a distal end of extension  110  and includes three terminals: first lug  504 , second lug  506 , and third lug  508 . Each of these terminals provides a connection point for providing electrical conduction through conductor rod  106  to work machine  100 . Second connector  502  is encased by cover  510 , which is an insulative material such as plastic, in the implementation illustrated. In one example, first lug  504  may be connected to a source of +1500 VDC, second lug  506  may be connected to a source of −1500 VDC, and third lug  508  may be connected to a reference voltage such as 0 VDC. Although not shown in the figures, the terminals may be connected to contactor  118  using a version of first arm  210 , second arm  214 , and third arm  212  illustrated in  FIG.  2   . Other types of physical connections between second connector  502  and contactor  118  may be used to achieve electrical conduction and multiple degrees of free movement between extension  110  and contactor  118  and will be within the knowledge of those skilled in the field. 
       FIG.  6    illustrates a longitudinal section of second connector  502  depicted in  FIG.  5   . As shown, a first pin  602  is positioned within second connector  502  in a substantially orthogonal relationship with first conductor  302 . First pin  602  is a conductive material, such as aluminum or copper, and in some embodiments resembles a dowel or pin in shape. At a proximal end, first pin  602  is connected to first conductor  302  to provide electrical conductivity between the parts. At its distal end, first pin  602  is connected to a first socket joint  604 . First socket joint  604  is also made of an electrically conductive material, such as aluminum or copper, and includes an orifice  618  for receiving first pin  602  at one end and a bowl-shaped concavity  620  at an opposite end. Concavity  620  functions as a socket joint and receives ball  605  of first lug  504 . The mating of first socket joint  604  and ball  605  creates a ball-and-socket joint, which permits rotational and pivotal movement of first lug  504 . Specifically, first lug  504  may twist and rotate within a semi-spherical space with respect to a surface  614  of second connector  502  where first lug  504  and first socket joint  604  meet. That is, in some examples, first lug  504  can be moved in a manner that its tip farthest from surface  614  can traverse a hemisphere generally bounded at its equator by second connector  502 . 
     Similarly, a second pin  606  is positioned within second connector  502  in a substantially orthogonal relationship with second conductor  304 . In the example of  FIG.  6   , second pin  606  and first pin  602  are substantially parallel to each other, exiting a bottom region of extension  110 . Second pin  606  is a conductive material and is connected to second socket joint  608 . As with first socket joint  604 , second socket joint  608  is electrically conductive and includes an orifice at one end for receiving second pin  606  at one end and a socket joint at the opposite end. Second lug  506  has an enlarged end in the general shape of a ball that is received in the socket joint of second socket joint  608 . As a result, as with first lug  504  and first socket joint  604 , second lug  506  is free to pivot and rotate within second socket joint  608  within a semi-spherical space with respect to surface  614  of second connector  502  where second lug  506  and second socket joint  608  intersect. 
     As well, third lug  508  is connected to third conductor  306  via a third pin  610  and a third socket joint  612 , as shown in  FIG.  6   . In some implementations, third socket joint  612  is affixed directly to third conductor  306  without the need for third socket joint  612 , as third conductor  306  is close to an outer surface of extension  110 . Third socket joint  612  includes a socket joint for receiving an end of third lug  508  having a general spherical shape with a diameter larger than the width of a shaft on the remainder of third lug  508 . The enlarged spherical shape, joined to the socket cavity within third pin  610 , enables semi-spherical movement of third lug  508  around surface  616  of second connector  502 . In the example illustrated, third lug  508  is parallel to first lug  504  and second lug  506 , while extending in an opposite direction (in the direction of the +Z axis compared with the −Z axis). 
     Referring to the examples of  FIGS.  6  and  7   , first conductor  302 , second conductor  304 , and third conductor  306  have different ending positions or terminations longitudinally within extension  110  to facilitate engagement with first pin  602 , second pin  606 , and third pin  610 .  FIG.  7    provides an isometric view of a version of second connector  502  with a perspective similar to  FIG.  6    with cover  510  removed. For instance, first pin  602  extends the farthest of the conductors (farther along the Y axis), reaching to near the distal end of extension  110 . Second conductor  304  and third conductor  306  end at positions closer to the proximal end of extension  110 . In this way, first pin  602  can pass laterally through second connector  502  without intersecting with either second conductor  304  or third conductor  306 . In the examples of  FIGS.  6  and  7   , third conductor  306  extends farther longitudinally than second conductor  304  such that third pin  610  (and third socket joint  612  if third pin  610  is not used) can pass directly to the outer surface of  512  without intersecting with either first conductor  302  or third conductor  306 . Second conductor  304  includes one or more apertures  702  around its perimeter ( FIG.  7   ), through which second pin  606  may pass to reach the outer surface of second connector  502 . Other arrangements or orderings of the conductors and their termination locations may be selected to comply with a desired implementation and are within the knowledge of those of ordinary skill in the art. 
     Therefore, as with the example in  FIGS.  2 - 4   , the example connector assembly  500  in  FIGS.  5 - 7    provides a structure configured to enable movement of extension  110  in multiple dimensions with respect to a contactor  118  and power rails  108 . Collectively, the ball-and-socket joints within each of first socket joint  604 , second socket joint  608 , and third socket joint  612  provide multiple degrees of freedom for the affiliated first lug  504 , second lug  506 , and third lug  508  to move relative to contactor  118  where they may be attached. Equivalent connections at contactor  118  (not shown) or connections on contactor  118  such as depicted for the first example in  FIG.  2    can coordinate with connector  502  to increase these degrees of freedom. For instance, if the position of work machine  100  changes in a lateral direction with respect to contactor  118 , for example, the ball-and-socket joints permit corresponding lateral movement at least for first lug  504 , second lug  506 , and third lug  508  to accommodate the change. Similarly, if extension  110  becomes displaced vertically with respect to contactor  118 , first lug  504 , second lug  506 , and third lug  508  can pivot upwardly or downwardly to accommodate the change and shield contactor  118  from forces that might otherwise detach contactor  118  from power rail  108 . And if extension  110  were to move angularly with respect to contactor  118 , the ball-and-socket joints permit the movement in a semi-spherical space for each of first lug  504 , second lug  506 , and third lug  508  such that the movement can be accommodated without forcing equivalent movement by contactor  118  on power rail  108 . The attachment mechanism chosen between second connector  502  and contactor  118  can impact the range of motion available for extension  110  and is subject to routine experimentation to those of ordinary skill in the field. Accordingly, connector assembly  500  of  FIGS.  5 - 7    can improve continued attachment of contactor  118  with power rails  108  as work machine  100  travels along haul route  101 , even as extension  110  moves laterally, vertically, or angularly with respect to power rails  108 , ensuring that work machine  100  remains attached to a supply of electrical power from power rails  108 . 
     Turning from the structure of terminal assembly  200 , connector assembly  114 , and connector assembly  500  as illustrated in  FIG.  1 - 7    to a method involving these structures,  FIG.  8    is a flowchart of a representative method for powering a work machine from a power rail along a side of a haul route. Generally embodied as  800  in  FIG.  8   , the method begins with steps  802  and  804  of extending a rod of concentrically arranged tubular conductors from a work machine and providing a connection assembly at a tip of the rod away from the work machine. As discussed in detail above, work machine  100 , such as a hauling truck at a mining site, can include conduction rod  106  with a plurality of conductive tubes, typically made of an aluminum alloy, arranged concentrically around a longitudinal axis. Near a tip  124  of conduction rod  106  distal from work machine  100 , connection assembly  114  is integrated into conduction rod  106 , as reflected in  FIG.  1   . 
     Further, in a step  806 , trailing arms are provided that are movably connected at one end to the connection assembly and at another end to a contactor. As implemented in the example of  FIG.  1   , contactor  118  is a structure that enables mechanical and electrical coupling with metal rails, such as power rails  108 , arranged along a side of a haul route  101 . Trailing arms  116  follow at an angle behind conductor rod  106  as work machine  100  travels on haul route  101  and provide a bridge between connection assembly  114  and contactor  118 . A step  808  in method  800  entails enabling a first rotation of the trailing arms at the connection assembly around a first axis substantially parallel to the trailing arms. As embodied in  FIG.  2   , a first rotation about a first axis may include a rotation of connection assembly  114  around axis A-A. A further step  810  includes enabling a second rotation of the trailing arms at the connection assembly and at the contactor about a second axis substantially perpendicular to the trailing arms.  FIG.  3    illustrates for one example that connection assembly  114  may include components to enable the rotation of trailing arms  116  around an axis B-B or axis C-C that are substantially perpendicular to axis A-A.  FIG.  8    further indicates to enable a third rotation of the trailing arms at the connection assembly and at the contactor about a third axis substantially perpendicular to the first axis and the second axis (step  812 ).  FIGS.  2  and  3    illustrate that hinge  320  and hinge  322  can provide additional rotation about axes D-D and E-E. 
     In further steps of method  800 , a connection is established between the contactor and a power rail arranged substantially in parallel with a haul route of a work machine (step  814 ), and electrical power is delivered from the power rail to the work machine (step  816 ). The connection between contactor  118  and power rails  108 , as shown in  FIG.  1   , provides access for work machine  100  to electrical power present on power rails  108 . Finally, step  818  of method  800  includes maintaining the connection during movement of the rod through one or more of the first rotation, the second rotation, and the third rotation of the trailing arms. Movement of work machine  100  along haul route  101  can lead to angular, vertical, or lateral motion of extension  110  relative to contactor  118 . In any of these dimensions, one or more of the axes of rotation within terminal assembly  200  permits trailing arms  116  to move as well and to compensate for the relative motion. Accordingly, terminal assembly  200  can absorb forces arising from the movement of extension  116  and avoid those forces being imparted on contactor  118 , which results in the contactor  118  maintaining its connection to power rails  108  and delivering electrical power to extension  116  while work machine  100  travels along haul route  101 . 
     Similar method steps may be employed with respect to connection assembly  500 . Embodied as  900  in the flowchart of  FIG.  9   , a representative method for powering a work machine from a power rail along a side of a haul route can begin with steps  902  and  904 , which are the same as steps  802  and  804  discussed above. A next step  906  entails providing trailing arms movably connected at one end to pins of the connection assembly and at another end to a contactor. As detailed above, connection assembly  500  includes pins  504 ,  506 , and  508  that may be connected to trailing arms, whether trailing arms  116  or a similar implementation, to contactor  118 . Contactor  118  may have similar pins within its structure for connection at to the trailing arms. Subsequent steps for method  900  entail enabling a first rotation of a first pin about semi-spherical space with respect to the connection assembly (step  908 ), enabling a second rotation of a second pin about a semi-spherical space with respect to the connection assembly (step  910 ), and enabling a third rotation of a third pin about a semi-spherical space with respect to the connection assembly (step  912 ). As illustrated in  FIGS.  5 - 7   , in some examples, pins  504 ,  506 , and  508  are secured to connector  502  through socket joints, such as  604 ,  608 , and  612 . In these ball-and-socket configurations, pins  504 ,  506 , and  508  are free to rotate around a semi-spherical space in response to angular or rotational forces applied against them. 
     In further steps of method  900 , a connection is established between the contactor and a power rail arranged substantially in parallel with a haul route of a work machine (step  914 ), and electrical power is delivered from the power rail to the work machine (step  916 ). The connection between contactor  118  and power rails  108 , as shown in  FIG.  1   , provides access for work machine  100  to electrical power present on power rails  108 . Finally, step  918  of method  900  includes maintaining the connection during movement of the rod through one or more of the first rotation, the second rotation, and the third rotation of the trailing arms. Movement of work machine  100  along haul route  101  can lead to angular, vertical, or lateral motion of extension  110  relative to contactor  118 . In any of these dimensions, the ball-and-socket arrangements for pins  504 ,  506 , and  508  permit trailing arms connected to those pins to move in reaction to forces applied by extension  110 . Accordingly, connector assembly  500  can help absorb forces arising from the movement of extension  110  and avoid those forces being imparted on contactor  118 , which results in contactor  118  maintaining its connection to power rails  108  and delivering electrical power to extension  116  while work machine  100  travels along haul route  101 . 
     Those of ordinary skill in the field will also appreciate that the principles of this disclosure are not limited to the specific examples discussed or illustrated in the figures. For example, while connector assembly  114  and second connector  502  have been discussed in the context of attachment to contactor  118  on the distal end of conductor rod  106 , other uses for them are feasible. Each could be implemented on the proximal end of conductor rod  106  for making mechanical and electrical connection at work machine  100 . Moreover, while the present disclosure address conductor rod  106  and terminal assembly  200  having three conductors, implementations have more or fewer conductors are contemplated. In addition, the principles disclosed are not limited to implementation on a work machine. Any moving vehicle deriving electrical power from a ground-based conductor rail could benefit from the examples and techniques disclosed and claimed. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure provides a system for a moving machine having a conductor rod configured to convey multiple poles of electrical energy from an energized rail to the moving machine, where the conductor rod has tubular conductors successively arranged concentrically around a longitudinal axis. A terminal assembly positioned on the conductor rod proximate the energized rail includes conductive extensions successively arranged concentrically around a terminal axis transverse to the longitudinal axis of the conductor rod. Individual ones of the conductive extensions rotationally branch from respective ones of the tubular conductors and extend to an exterior of the conductor rod. Metal pins positioned transversely to the terminal axis can also rotate and are electrically connected to corresponding ones of the conductive extensions. Conductive arms connected through respective hinge joints to the rotatable pins are also connected to a contactor that slides on the energized rail. As a result, the terminal assembly enables multiple degrees of freedom for the conductor rod to move relative to the contactor, avoiding detachment of the contactor from the energized rail as the machine moves. 
     As noted above with respect to  FIGS.  1 - 7   , an example conductor rod and terminal assembly generally includes a conductor rod  106  with an extension  110  that is extendable or retractable from a work machine  100 . Conductor rod  106  and extension  110  include concentrically arranged metal tubes, each configured to conduct a different pole of electrical power to work machine  100 . A distal end of extension  110  has a connector assembly  114  that receives electrical power from a power rail  108 . Specifically, a rotational interface  202  protrudes from a lateral side of extension  110  and contains concentrically arranged conductive pins, each of which rotationally connects with a corresponding conductor in extension  110 . The pins are respectively connected with lugs that enable rotation around an axis orthogonal to the pins. Arms are coupled to the lugs via hinges that provide further axes of rotation. Finally, the arms are pivotally and rotationally coupled to a contactor  118  that slides along power rail  108  as work machine  100  moves. 
     In the examples of the present disclosure, the terminal assembly  200  and the connector assembly  114  enable movement of extension  110  with multiple degrees of freedom with respect to contactor  118 . If irregularities in haul route  101  or in steering cause work machine  100  to veer laterally with respect to contactor  118 , the hinged connections on connector assembly  114  and contactor  118  enable trailing arms  116  to move in a way to accommodate the changing relative positions. Similarly, vertical changes to extension  110  can be accommodated through the rotational features of various lugs within connector assembly  114  and contactor  118 . As well, angular displacement of extension  110  relative to contactor  118  can be absorbed with, in part, the rotational features of rotational interface  202 . On balance, terminal assembly  200  can provide multiple degrees of freedom for extension  110  to move relative to contactor  118 , such that forces on contactor  118  that may otherwise cause detachment from power rail  108  are avoided, ensuring continued supply of electrical power to work machine  100  during movement along haul route  101 . 
     Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations or their equivalents. As used herein, the word “or” refers to any possible permutation of a set of items. For example, the phrase “A, B, or C” refers to at least one of A, B, C, or any combination thereof, such as any of: A; B; C; A and B; A and C; B and C; A, B, and C; or multiple of any item such as A and A; B, B, and C; A, A, B, C, and C; etc. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.