Abstract:
A control system includes at least one lever configured to receive an operator input, a bellcrank coupled to the at least one lever and configured to rotate when the operator input exceeds a threshold, a support structure of the bellcrank which movably holds the bellcrank, and at least one magnet which forms a magnetic field which forms a positive detent between the bellcrank and the support structure of the bellcrank.

Description:
BACKGROUND 
       [0001]    Detents are present on aircraft for pilot assistance. For ease of use, most aircraft controls have detents about a neutral position. So-called return features are typically provided such that, in the absence of input, the control is restored or returned to the neutral position. 
         [0002]    Conventional detents include spring capsules with an adjustable preloaded spring that provides resistance to movement from the neutral position. Another conventional detent includes a cam and follower system, which is also usually adjustable with a spring having a known force or spring constant that must be overcome to displace the control from the neutral position. Both of these detents are costly and time consuming to design and manufacture. Moreover, given the presence of the controls on an aircraft, additional features must be included in case of jamming. 
       BRIEF SUMMARY 
       [0003]    An embodiment is directed to a method of installing a detent comprising: deploying a pair of magnets in a control system of an aircraft, wherein the magnets are configured based on a breakout force needed to overcome a magnetic detent of the control system. 
         [0004]    In some embodiments, deploying the magnets comprises mounting the magnets at a specified location of the control system. 
         [0005]    In some embodiments, deploying the magnets comprises installing the magnets internal to a pedal or stick control module. 
         [0006]    In some embodiments, the aircraft comprises a helicopter, and wherein the control system is associated with at least one of: collective controls, cyclic controls, and yaw controls. 
         [0007]    In some embodiments, the magnets are permanent magnets. 
         [0008]    In some embodiments, the method further comprises receiving feedback regarding the magnetic detent, and adjusting at least one parameter associated with the magnetic detent based on the feedback. 
         [0009]    In some embodiments, the adjusting of the at least one parameter comprises at least one of selecting a second pair of magnets to replace or supplement the deployed magnets, and modifying a distance between the deployed magnets. 
         [0010]    An embodiment is directed to a control system comprising: at least one lever configured to receive an operator input, a bellcrank coupled to the at least one lever and configured to rotate when the operator input exceeds a threshold, a support structure of the bellcrank which movably holds the bellcrank, and at least one magnet which forms a magnetic field which forms a positive detent between the bellcrank and the support structure of the bellcrank. 
         [0011]    In some embodiments, the at least one magnet which forms the magnetic field comprises a first magnet attached in the bellcrank and a second magnet attached to the support structure of the bellcrank. 
         [0012]    In some embodiments, the at least one magnet is selected to require a breakout force to be provided by a pilot of an aircraft via the operator input in an amount that exceeds the threshold for the bellcrank to rotate. 
         [0013]    In some embodiments, the at least one magnet is installed internal to a pedal or stick control module of an aircraft. 
         [0014]    In some embodiments, the control system is associated with at least one of: collective controls, cyclic controls, yaw controls, or combinations thereof. 
         [0015]    In some embodiments, the bellcrank and support structure are designed with non-magnetic aluminum. 
         [0016]    In some embodiments, the control system further comprises a linkage coupled to the at least one lever and to the bellcrank. 
         [0017]    In some embodiments, the at least one magnet comprises a neodynium magnet. 
         [0018]    An embodiment is directed to a helicopter comprising a control system, such as one or more of the control systems described herein. 
         [0019]    An embodiment is directed to a vehicle comprising a control system, such as one or more of the control systems described herein. 
         [0020]    Additional embodiments are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
           [0022]      FIG. 1  is a general perspective side view of an exemplary aircraft; 
           [0023]      FIG. 2  is a block diagram of an exemplary control system; 
           [0024]      FIG. 3  illustrates an exemplary magnetic detent; 
           [0025]      FIG. 4  illustrates a flow chart of an exemplary method; 
           [0026]      FIGS. 5A-5B  illustrate an exemplary design application; 
           [0027]      FIGS. 6A-6B  illustrate an exemplary design application; and 
           [0028]      FIGS. 7A-7B  illustrate an exemplary installation for a collective channel. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection. 
         [0030]    Exemplary embodiments of apparatuses, systems, and methods are described regarding the design and use of a detent, such as a magnetic positive detent. The detent may be used in connection with an aircraft. For example, the detent may be associated with a rotorcraft (e.g., helicopter) pilot input. The strength of the detent may be based on a strength of a selected magnet and a distance between magnets. 
         [0031]    Referring now to  FIG. 1 , a general perspective view of a helicopter  10  is shown. The helicopter  10  includes a main rotor assembly  12  and tail rotor assembly  14 . Although a particular helicopter configuration is illustrated and described in the disclosed embodiment, other configurations and/or machines (e.g., other aircraft configurations) may be used in connection with this disclosure such as coaxial helicopters, helicopters with pusher propellers, or fixed wing aircraft. 
         [0032]    Turning to  FIG. 2 , a control system  200  in accordance with one or more embodiments is shown. The system  200  may include levers  208 . The levers  208  may be used to enable an operator (e.g., a pilot) to apply an input force. For example, the operator may push down on the levers  208  in the input direction shown in  FIG. 2 . Of course, one skilled in the art would appreciate that the operator could also pull up on the levers  208 , such that the input direction would point upwards in such an instance. While described in the context of a human pilot, it is understood that aspects could be used in automated pilot control systems or optionally piloted control systems. Further, while shown with dual levers  208 , it is understood that the control system  200  can have a single lever or more than two levers in other aspects. 
         [0033]    Based on the downward applied input to the levers  208  shown in  FIG. 2 , a bellcrank  216  may be caused to rotate in an output direction as shown. The bellcrank  216  may rotate based on a linkage  224  between the levers  208  and the bellcrank  216 . While shown as having opposite rotational directions, it is understood that the control system  200  could have the output direction be in the same rotational direction as the linkage  224  in other aspects. 
         [0034]    In order to keep the bellcrank  216  from rotating in the absence of an applied input to the levers  208 , a detent may be used. An example of such a detent is shown in  FIG. 3 . The detent may correspond to two magnets  310 . A first of the magnets  310  may be staked in, or coupled to, the bellcrank  216 . A second of the magnets  310  may be staked in, or coupled to, a support structure  322  for the bellcrank  216 . The first and second magnets  310  may be oriented to attract one another, thereby creating a positive detent. In some embodiments, one or both of the first and second magnets  310  may include a permanent magnet. The magnets  310  may be neodymium magnets. 
         [0035]    While shown with a simplified linkage  224  between the levers  208  and the bellcrank  216 , it is understood that additional linkages could be used to transmit force and that the detent could be disposed in these additional linkages in other aspects. While shown with a pair of magnets, in other aspects, only a single magnet  310  in conjunction with a magnetizable material may be used. By way of example, where one of the magnets  310  is attached to the bell crank  216  and the support structure  322  is made of a magnetizable material such as steel, the requisite magnetic force between the bell crank  216  and support structure  322  is created. 
         [0036]    The strength of the magnets  310  and the distance between the magnets  310  may be selected to control the force needed to be applied at the levers  208  to break or overcome the detent. Typically, the mechanical components of the system  200  are held to tight tolerances, such that the distance between the first and second magnets  310  is also well-controlled. As such, the force needed to be applied at the lever  208  to break or overcome the detent would be repeatable. 
         [0037]    Turning now to  FIG. 4 , a flow chart of an exemplary method  400  is shown. The method  400  may be executed in connection with one or more systems, components, or devices, such as those described herein. The method  400  may be used to provide a magnetic detent for a control system of an aircraft. 
         [0038]    In block  402 , a desired breakout force needed to overcome a detent may be selected. The breakout force may be selected based on a specification or requirement associated with a given control system. 
         [0039]    In block  404 , magnets may be selected. The selection of the magnets may be based on the breakout force selected in block  402 . The selection of the magnets may be based on a mounting location for the magnets, which may be a function of the control system. 
         [0040]    In block  406 , the magnets may be deployed. For example, as part of block  406 , the magnets may be mounted at a specified location of the control system. 
         [0041]    In block  408 , feedback may be obtained from an operator of the control system regarding the magnetic detent. If the feedback indicates a lack of satisfaction with the detent, one or more parameters associated with the detent may be adjusted. For example, different magnets may be selected to replace or supplement the current/existing magnets, or a distance between the magnets may be modified. 
         [0042]    The method  400  is illustrative. In some embodiments, one or more of the blocks or operations (or a portion thereof) may be optional. In some embodiments, one or more additional blocks or operations not shown may be included. In some embodiments, the blocks or operations may execute in an order or sequence that is different from what is shown in  FIG. 4 . 
         [0043]    In some embodiments, a magnet installed in a bellcrank may be designed to rotate, e.g., +/−10 degrees. As described above, one or more magnets may be installed as part of the bellcrank and/or as part of a fixed support. In some embodiments, magnets may be initially inline, with a 0.020 inch gap. A detent force of approximately 5 pounds may be provided. 
         [0044]    Referring to  FIGS. 5A-5B , an application example in accordance with one or more embodiments is shown. In  FIG. 5A , a first magnet  504  coupled to a fixed support and a second magnet  512  coupled to a rotating bellcrank are shown in a first position. The magnets  504  and  512  may each generally reside at a location or distance from a center of the bellcrank corresponding to a radius ‘r’ of a circle. In some embodiments, the radius ‘r’ may be equal to 1 inch. The magnets  504  and  512  might not be rotated or displaced relative to one another in  FIG. 5A . 
         [0045]    In  FIG. 5B , the magnet  512  is shown as having been rotated at an angle ‘φ’ relative to the positioning of the magnet  512  in  FIG. 5A . The displacement ‘d’ of the magnet  512  may be calculated as: d=2*r*sin(φ/2). Thus, if ‘φ’ equals 10 degrees and ‘r’ equals 1 inch, ‘d’ may be equal to 0.174 inches. The detent can be set to where the magnetic force maintains the magnets  512 ,  504  in alignment or returns them to alignment as shown in  FIG. 5A  when within a given displacement d, but is insufficient to force the magnets  512 ,  504  back into alignment when outside of the displacement d. 
         [0046]    Referring to  FIGS. 6A-6B , an application example in accordance with one or more embodiments is shown. The application of  FIGS. 6A-6B  may be analogous to the embodiment of  FIGS. 5A-5B , but may include a small offset or gap between magnets. Specifically, in  FIG. 6A , a first magnet  604  that may be coupled to a fixed support and a second magnet  612  that may be coupled to a rotating bellcrank are shown in a first position. The magnets  604  and  612  may be offset from one another by a distance ‘x’. In some embodiments, ‘x’ may be equal to 0.020 inches. 
         [0047]    In  FIG. 6B , the magnet  612  may have been moved relative to the positioning of the magnet  612  in  FIG. 6A . Specifically, the magnet  612  may be moved by a distance ‘d’ in a direction that is substantially perpendicular to the direction ‘x’. Accordingly, a total distance ‘z’ between the magnets  604  and  612  may be approximated as a hypotenuse of right triangle: z=sqrt(x̂2+d̂2). Thus, if ‘x’ equals 0.020 inches and ‘d’ equals 0.174 inches, then ‘z’ may equal 0.175 inches. For a small offset or gap ‘x’ and small angle of rotation ‘φ’, ‘z’ may approximately be equal to ‘d’. 
         [0048]    In some embodiments, a magnetic force of cylinders may be solved numerically to relate, e.g., magnetic force to distance. Relative to a theoretical calculation, the actual force at a given distance in practice may be less due to an interaction of magnetic field lines away from an axis of action. In some embodiments, an attraction force at full travel may be preferred to aid a return to a center or neutral position. 
         [0049]    Referring to  FIGS. 7A-7B , an application example in accordance with one or more embodiments is shown. 
         [0050]    In  FIG. 7A , a first magnet  704  that may be coupled to, or staked in, a fixed support or support bracket and a second magnet  712  that may be coupled to, or staked in, a rotating stick assembly  720  are shown. The stick assembly  720  may correspond to a pilot collective stick assembly. The portion of  FIG. 7A  denoted by dashed circle  728  is shown in greater detail in  FIG. 7B . 
         [0051]    In  FIG. 7B , the magnets  704  and  712  are shown as having an offset or gap of ‘x’, which may be equal to 0.020 inches. 
         [0052]    In some embodiments, magnets may be used to provide a detent with no moving parts. Therefore, such a detent is not susceptible to jamming. The use of the magnets as a detent provides for a simplistic design and dramatically reduces engineering and maintenance costs. The magnets may allow the detent to function in a number of directions (e.g., rotational directions). Machined bellcranks and supports are typically designed with non-magnetic materials (e.g., non-magnetic aluminum). As such, the bellcranks and supports will not impact the performance of the magnetic detent. 
         [0053]    Use of magnets as part of a detent reduces costs associated with design, fabrication, deployment and maintenance relative to conventional detents. One merely has to specify a pair of magnets and a mounting location as part of the design process. Since the magnets may be staked into existing components, the magnets add very little weight and little to no volume to an existing system. If during operator evaluation the detent is deemed inadequate, it would be possible to specify two new magnets and replace them without having to undergo a major redesign process. 
         [0054]    In some embodiments, such as in connection with legacy mechanical systems, a magnetic detent may be used to provide a cheap alternative to match more expensive aircraft solutions. On more current fly-by-wire aircraft, the magnetic detent would further eliminate lower reliability mechanical parts from a control system. The magnetic detents may be installed internally to a pedal or stick control modules. 
         [0055]    Aspects of the disclosure may be used in connection with one or more control systems, such as one or more control systems associated with an aircraft. For example, in the context of a helicopter, a detent may be used in connection with collective controls, cyclic controls, or yaw controls. Additionally, while described in the context of aircraft, it is understood that aspects could be used in other forms of control systems, such as those for industrial machinery, or vehicles such as locomotives, cars, trucks, boats, or ships. 
         [0056]    As described herein, in some embodiments various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses, systems, or devices. For example, in some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations. 
         [0057]    Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional.