Abstract:
A self-centering hand-operated controller and control system including a self-centering hand-operated controller for operating a machine requiring at least one directional control input.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The instant invention is directed toward a control system and a hand-operated controller for a machine driven by at least one directional control input. 
         [0002]    As a non-exclusive example of such a machine,  FIG. 1  illustrates an aerial platform  10  (also known as a “cherry picker”) as an articulated crane  12  provided on a vehicle or truck  11  for positioning the crane  12  into the vicinity of the workspace where overhead work is to be performed. A terminal end of the crane  12  is provided with a mobile operator station  14 . 
         [0003]    The joints of the crane  12  are moved by a hydraulic system, as known in the art, wherein high-pressure liquid (a hydraulic fluid having non-compressible qualities, such as oil) is transmitted throughout the crane  12  from a reservoir  2  to hydraulic actuators  4  (e.g., hydraulic cylinders and motors) via hydraulic lines or hoses  6  by means of a pump  1 . The movement of the crane is controlled by control valves which regulate pressure and flow of the fluid in the hydraulic lines  6 . 
         [0004]    Cranes such as the aerial platform  10  in  FIG. 1  are typically provided with two sets of control valves. The first set of control valves are ground-based control valves  3  at the base of the crane  12  for articulation of the crane  12  from the ground. The second set of control valves are implemented as remote control valves  5  located in the operator station  14  for controlling articulation of the crane  12  remotely from the top of the crane  12 . The remote control valves  5  are particularly convenient, as it allows the worker in the operator station  14  to control his position as he or she performs his or her work. 
         [0005]    The controller for actuating the remote control valves  5  is typically embodied as a control assembly, diagrammatically illustrated in  FIG. 2 , and may include a hand-operated grip control  15 . In the prior art, the remote control valves  5  would comprise control valves similar to the ground-based control valves  3 , comprising a plurality of valves  18 , 19  located in and mobile with the operator station  14 . The grip control may comprise a handle  16  that articulates as many as four valves  18  or more. The four valves  18  direct fluid pressure through the hydraulic hoses and tubes from the reservoir  2  to the hydraulic actuators  4  to accomplish movement of the various parts of the crane  12 . In addition, the grip control may include a safety trigger  17  articulating a safety valve  19 . The safety valve  19  typically would operates such that if the trigger  17  of the grip control  15  is not pressed, no fluid is allowed to the other cylinders  18  downstream so that no movement of the crane  12  takes place. 
         [0006]    As embodied in the prior art, the grip control  15  enables precision movement of each of the different joints of the crane  12  with a single hand, leaving the worker&#39;s other hand free for other purposes. However, as known in the art, it is necessary to provide hydraulic hoses and tubes, in addition to those connecting to the hydraulic actuators  4 , all the way up the crane to the second control valves  5  of the operator station  14  for each hydraulic actuator  4  to be controlled. These hydraulic hoses terminate in the valves  18 , one for each hose for each actuator  4  to be controlled. 
         [0007]    This design, however, has several disadvantages. The additional hydraulic hoses required to be run up the crane  12  to the control assembly  5  add weight, expense, and complexity to the crane, as well as requiring that pressurized fluid be maintained at the mobile operator site  14 . The control assembly  5  further requires complex mechanics to facilitate precise changes to the fluid pressure in the hoses in response to the movements of the grip control  15 , mechanics that also exist in the ground-based control valves  3  at the base of the crane  12 . 
         [0008]    There is therefore a need for a control system embodying the advantages of the grip control  15  for precise, one-handed operation of all the hydraulic operations of the crane  12  while reducing complexity, weight, and cost. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to solving the problems described above. The present invention comprises a hand-grip control configured for a plurality of different articulated movements, including a spring-loaded trigger for activating and deactivating the control, the control configured to actuate sensors responsive to each of the articulated movements. 
         [0010]    According to a first aspect of the invention, the hand-grip control of the invention is a self-centering hand-operated control device for remotely controlling a hydraulic machine having at least three movable positioning elements, comprising an elongated handle with a coupling portion at one end and a gripping portion extending from the coupling portion along a longitudinal axis, the gripping portion being configured to be gripped by an operator&#39;s hand; a control assembly with a first end rotatably coupled to the coupling portion of the elongated handle such that the elongated handle is rotatable about the longitudinal axis, the control assembly extending along a first axis perpendicular to the longitudinal axis from the first end to a second end configured to be mounted to a surface, the control assembly including a plurality of sensors each configured to generate signals responsive to an operative movement of the elongated handle about any of the longitudinal axis, the first axis, and a second axis orthogonal to the longitudinal and first axes, and the control assembly also including centering mechanisms configured to resiliently maintain the elongated handle and the control assembly in a neutral position respective to the longitudinal axis, the first axis, and the second axis in the absence of an operative force upon the elongated handle. 
         [0011]    According to a second aspect of the invention, there is provided a self-centering hand-operated control system for remotely controlling a hydraulic machine having at least three movable positioning elements, comprising a hand-operated control device as described above, a control interface configured to receive the generated signals from the control device and pilot a hydraulic valve device configured to operate hydraulic motors for positioning the movable positioning elements; and a transmission interface for transmitting the generated signals from the control device to the control interface. 
         [0012]    In one embodiment of the invention, one or more of the first, second, and third sensors are potentiometers operable in response to the first, second, and third movements, respectively 
         [0013]    In another embodiment of the invention, one or more of the first, second, and third sensors are each non-contacting rotary sensors using a Hall effect to measure relative angular displacement. 
         [0014]    In yet another embodiment of the invention, the first, second, and third sensors are each optical devices configured to measure relative angular displacement. 
         [0015]    In yet another embodiment of the invention, the elongated handle comprises a trigger lever extending along the longitudinal length of the elongated handle and configured to rotate about the longitudinal axis with the rotation of the elongated handle, the trigger lever configured to generate a trigger signal responsive to an operative squeezing of the trigger lever by the operator&#39;s hand. 
         [0016]    In a further embodiment of the invention, the control assembly further comprises a parallelogram mechanism pivotally movable by a horizontal displacement along a horizontal direction of the elongated handle, the parallelogram mechanism including a fourth electronic sensor configured to generate a signal responsive to the horizontal displacement. 
         [0017]    In a yet still another embodiment of the invention, the control interface is further configured to override the first, second, and third signals received respectively from the first, second, and third electronic sensors upon receiving the trigger signal. 
         [0018]    In a yet further embodiment of the invention, each of the centering mechanisms are configured to limit an angular displacement to a maximum angular displacement. 
         [0019]    In yet another further embodiment of the invention, each centering mechanism comprises first and second commonly pivoted spring-arms each having a middle portion, a distal end, a proximal end opposite the distal end, and a lateral extension, each of the proximal end, the distal end, and the lateral extension extending from the middle portion, the first and second spring-arms configured to rotate with respect to each other about a common axis through the respective middle portions, the middle portions of the spring-arms having openings for receiving a pivot shaft, the distal ends of the spring-arms being connected to each other by a tension device configured to urge the distal ends toward each other, and the lateral extensions of the spring-arms having stop portions configured to limit a rotational motion of said spring-arms about the common axis to the maximum angular displacement. 
         [0020]    In yet another still further embodiment of the invention, the stop portions of each spring-arm is configured to abut against a corresponding abutment portion of the opposite spring-arm. 
         [0021]    In still yet another further amendment of the invention, the elongated handle is coupled to a first section of the control assembly, the first second including the plurality of sensors and the centering mechanisms, the first section is pivotably mounted to a second section of the control assembly, the second section including the parallelogram mechanism, the first section configured to pivot about the first axis relative to the second section, a first of the plurality of sensors being configured to indicate an operative force to pivot the first section about the second section, the elongated handle comprises a first pivot shaft extending along the longitudinal axis, the first pivot shaft configured to rotate with a first operative motion about the longitudinal axis and further configured to engage with a second of the plurality of sensors located at an end of the first pivot shaft, an outer peripheral surface around a circumference of the first pivot shaft at an end of the first pivot shaft having a cavity extending into the surface of the first pivot shaft, the end of the first pivot shaft extending through an opening in a first leaf spring housing, the first leaf spring housing including a first leaf spring having an first engagement portion in engagement with the outer peripheral surface of the first pivot shaft and configured to reversibly enter the first cavity of the first pivot shaft to prevent a rotation of the first pivot shaft about the longitudinal axis where a torque applied to the first pivot shaft is less than a first predetermined value greater than zero, and one of the arms of the parallelogram mechanism is connected to a second pivot shaft configured to rotate responsive to a horizontal displacement of the horizontal body, the second pivot shaft configured to engage with the displacement sensor, an outer peripheral surface around a circumference of the second pivot shaft at an end of the second pivot shaft having a cavity extending into the surface of the second pivot shaft, the end of the second pivot shaft extending through an opening in a second leaf spring housing, the second leaf spring housing including a second leaf spring having a second engagement portion in engagement with the outer peripheral surface of the second pivot shaft and configured to reversibly enter the second cavity of the first pivot shaft to prevent a rotation of the second pivot shaft about an axis through a center of the second pivot shaft where a torque applied about axis through a center of the second pivot shaft is less than a predetermined value greater than zero. 
         [0022]    These and other embodiments and advantages of the present invention may become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  diagrammatically illustrates an exemplary embodiment of a truck-based aerial platform including a crane and a mobile operator station with an exemplary control system in the prior art. 
           [0024]      FIG. 2  diagrammatically illustrates an exemplary embodiment of a hand-grip control as known in the art for actuating the position of the aerial platform of  FIG. 1 . 
           [0025]      FIG. 3  diagrammatically illustrates an exemplary embodiment of a truck-based aerial platform including a crane and a mobile operator station with a control system in accordance with the invention. 
           [0026]      FIG. 4  provides a perspective view of a hand-operated control device in accordance with the invention. 
           [0027]      FIG. 5  provides a detail of  FIG. 3  illustrating a spring-arm centering assembly in accordance with the invention. 
           [0028]      FIG. 6  provides a diagrammatic top view of the spring-arm centering assembly in accordance with the invention. 
           [0029]      FIG. 7  provides an exploded view of the spring-arm centering assembly in accordance with the invention. 
           [0030]      FIG. 8  provides a perspective view of a leaf spring centering assembly in accordance with the invention. 
           [0031]      FIG. 9  provides an exploded view of an elongated handle of the of the control device, including the spring-arm assembly and the leaf spring assembly associated with the handle for centering the handle. 
           [0032]      FIGS. 10   a  and  10   b  illustrate a detail of the elongated handle from a rear of the control device and a detail from a front exterior of the elongated handle, respectively, the elongated handle being in a neutral position. 
           [0033]      FIGS. 11   a  and  11   b  illustrate the detail of the rear and a front exterior, respectively corresponding to  FIGS. 10   a  and  10   b,  wherein the elongated handle is in a biased position. 
           [0034]      FIG. 12  is an exploded view of a base portion of the control assembly, including the spring-arm assembly and the leaf spring assembly associated with the handle for centering the base portion. 
           [0035]      FIG. 13  is a similar view of  FIG. 12  from another perspective. 
           [0036]      FIGS. 14   a  and  14   b  provide opposing side views of the assembly of  FIGS. 12 and 13  in a neutral position. 
           [0037]      FIGS. 15   a  and  15   b  correspond to  FIGS. 14   a  and  14   b  wherein the assembly of  FIGS. 12 and 13  are in a biased position. 
           [0038]      FIG. 16  is an exploded view of an assembly of another part of the grip controller. 
           [0039]      FIGS. 17   a  and  17   b  show top and bottom views, respectively, of the assembly of  FIG. 16  in a neutral position. 
           [0040]      FIGS. 18   a  and  18   b  correspond to  FIGS. 17   a  and  17   b  wherein the assembly of  FIG. 16  are in a biased position. 
           [0041]      FIG. 19  is an exploded view of the parallelogram assembly of the grip controller. 
           [0042]      FIGS. 20   a  and  20   b  show opposing side views of the parallelogram assembly of  FIG. 19 . 
           [0043]      FIGS. 21   a  and  21   b  correspond to  FIGS. 20   a  and  20   b  wherein the parallelogram assembly of  FIG. 19  are in a biased position. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0044]      FIG. 3  shows an exemplary machine  10  controlled by directional inputs that is improved by the invention. The exemplary machine  10  includes a crane  12  positioned on a vehicle or truck  11 . The truck  11  is used for positioning the crane  12  into the vicinity of the workspace where overhead work is to be performed. 
         [0045]    In  FIG. 3 , the crane  12  is hydraulically actuated. Hydraulic motors or actuators  4  are located on the crane  12  as known in the art for elevating and positioning the crane  12 . 
         [0046]    In accordance with the invention, a grip controller  21  in the operator station  14  remotely controls the hydraulic actuators  4  from the position of the operator station  14 , thereby enabling the operator to precisely position the operator station  14  to where overhead work is to be performed. The grip controller  21  is connected via a transmission interface  50  to a control interface  54  configured to receive signals from the grip controller  21 . The transmission interface  50  connecting the grip controller  21  and the control interface  54  may be electric lines (e.g., electric cabling), optical lines (e.g., fiber-optic cabling) or other means of signal transport. 
         [0047]    In an embodiment of the invention, the control interface  54  includes a computer device having at least a CPU, a random-access memory, a first signal interface for receiving and translating signals from the grip controller  21  into data readable by the CPU, a second signal interface for transmitting signals to the control valves  3 , and a non-volatile storage memory storing a program for configured to cause the CPU to translate signals received from the grip controller  21  into corresponding signals to the control valves  3  so that operation of the grip controller  21  will cause the hydraulic actuators  4  of the crane  12  to move in a known, predictable, and reliable manner. 
         [0048]    One embodiment of the inventive grip controller  21  is shown in  FIG. 4 . The grip controller  21  includes an elongated handle  22  configured to be gripped by an operator&#39;s hand, one end rotatably connected to an upper housing  80  of a control assembly  28  along a longitudinal axis A L . 
         [0049]    The elongated handle  22  is connected to a sensor  34   c  configured to generate a signal corresponding to a rotational movement R 3  and/or angular position of the handle  22 , caused by an operative twisting motion of the handle  22  about the longitudinal axis A L . The grip controller is further configured to enable and sense rotational motions R 1  and R 2  about respective axes A 1  and A 2 , as will be described later. 
         [0050]    The upper housing  80  is mounted upon a parallelogram mechanism  90 . The parallelogram mechanism  90  includes two arms configured to extend in substantially a direction of a first axis A 1  perpendicular to the longitudinal axis A L . The parallelogram mechanism  90  is mounted on a base such that the parallelogram mechanism  90  does not rotate about the first axis A 1 , and the upper housing  80  is rotatably mounted on the parallelogram mechanism so that it can rotate about the first axis A 1  responsive to an operative side-to-side motion of the handle  22 . 
         [0051]    The upper housing  80  also includes a pivot mechanism so that the upper housing  80  may pivot about a second axis A 2  in response to an operative up or down motion of the handle  22 . 
         [0052]    The handle  22  also includes in an embodiment of the invention a squeeze trigger  24  extending along a longitudinal length of the elongated handle  22 . The squeeze trigger  24  rotates about the longitudinal axis A L  with the rotation of the elongated handle  22 , and the squeeze trigger  24  is connected to a switch (not shown) configured to generate a trigger signal responsive to an operative squeezing of the squeeze trigger  24  by the operator gripping the handle  22 . This squeeze trigger  24  is intended as a safety mechanism, and sends a signal to the control interface  54  to immediately override any other control input and stop all motion of the crane  12 . 
         [0053]    The upper housing  80  of the control assembly  28 , as shown in  FIG. 4  and further detailed in  FIGS. 9-18 , is configured for movement about the longitudinal, first, and second axes A L , A 1 , A 2  in response to three operative rotational movements R 3 , R 1 , R 2  about the respective axes. Each rotational movement generates a corresponding signal from one of three sensors  34   a,    34   b,    34   c.  In addition, the parallelogram mechanism  90  control assembly  28  allows a fourth movement in a horizontal direction H responsive to an operative horizontal displacement D H  of the handle  22  and the upper housing  80 . The horizontal displacement D H  is measured by a displacement sensor  34   d.    
         [0054]    Signals from each of the sensors  34   a,    34   b,    34   c  and  34   d  are transmitted to the control interface  54  in order to control the movements of the hydraulic actuators  4 . As a result, the operative movements of the grip controller  21  operate the crane  12 . 
         [0055]    It is most important that a neutral position of the grip controller  21  be established between the grip controller  21  and the control interface  54 . The neutral position is a position of the grip controller  21  when no operative force is applied by an operator, whereupon to the corresponding signals from the sensors  34   a,    34   b,    34   c  and  34   d  causes the control interface  54  to maintain the crane  12  in a still position. 
         [0056]    Accordingly, the embodiment of the invention includes mechanisms to maintain the grip controller  21  in the neutral position, such that each of the sensors  34   a,    34   b,    34   c  and  34   d  are maintained in corresponding neutral positions. In the embodiment, each of the movements R 3 , R 1 , R 2 , D H  are regulated by a centering mechanism incorporating a spring-arm mechanism  100  and a leaf spring assembly  200 . 
         [0057]    In  FIGS. 5-7 , a spring-arm mechanism  100  is shown. A first pivot arm  110  and a second pivot arm  120  are assembled together to pivot about a common axis through a middle of each pivot arm. Each pivot arm also has a distal end  112 ,  122 , each provided with holes  114 ,  124  wherein a spring  130  is attached. Each pivot arm is yet further provided with a lateral extension  116 ,  126  extending in a direction substantially parallel to an axis from the pivot arms to the distal ends  112 ,  122 , the lateral extensions  116 ,  126  each having protrusions that will stop a rotational motion of the pivot arms at a predetermined rotational displacement. The maximum rotational displacement corresponds to a length of the lateral extensions  116 ,  126 . The pivot arms in  FIG. 5-7  are secured together upon a common shaft by a washer  140  and a nut  142 , and a rotational motion of the pivot arms  110 ,  120  with respect to each other may be facilitated by an intermediate washer  141  provided between the pivot arms  110 ,  120 . 
         [0058]    The spring-arm mechanism  100  is actuated by lateral tabs  146 ,  148  which are provided on the grip controller  21  for each of the movements R 3 , R 1 , R 2 , D H . In an operative motion of the grip controller about one of the operative axes, one the lateral tabs  146 ,  148  will move with the operative motion while the other of the lateral tabs  146 ,  148  will remain in place. As shown in  FIG. 5 , both lateral tabs  146 ,  148  are in the neutral position wherein the tabs are above and below each other. The lateral tabs  146 ,  148  are above and below each other such that the spring-arms  110 ,  120  are closest to each other and the spring  130  is in a state of least tension. 
         [0059]    The neutral position is further maintained by a leaf spring assembly  200  as shown in  FIG. 8 . In the embodiment, each of the movements R 3 , R 1 , R 2 , D H  rotates a corresponding shaft  210 , an outer peripheral surface of each shaft having a cavity  216  extending into the surface of the shaft. The shaft  210  is mounted through a leaf spring housing  201  which includes slots  202  for receiving and securing a leaf spring  220 . The leaf spring  220  extends in a longitudinal direction with a V-shaped bend extending transversely to the longitudinal direction of the leaf spring  220 , the V-shaped bend configured to fit within the cavity  216  on the circumferential periphery of the shaft. 
         [0060]    In the embodiment, a key  212  is presented by the shaft to interface with a rotatable part of a sensor. 
         [0061]    When in the neutral position, the leaf spring  220  is urged into the cavity  216  of the shaft via residual tension in the spring. The V-shaped bend maintains the shaft in the neutral position until an operative torque is applied to turn the shaft within the leaf spring housing  201  is forceful enough to overcome the tension in the spring and cause the V-shaped bend to exit the cavity  216 . The tension of the leaf spring  220  will then maintain the V-shaped bend of the leaf spring  220  in contact with the circumferential surface of the shaft until the cavity  216  of the shaft is again brought into contact with the V-shaped bend. 
         [0062]    The centering mechanism operates as follows. The shaft  210  is urged by the spring-arms  110 ,  120  such that the leaf spring  220  is brought into proximity of the cavity  216 . In an embodiment of the invention, spring-arms  110   a - d,    120   a - d  are provided at each of the sensors  34   a,    34   b,    34   c  and  34   d  urge the grip controller  21  into neutral positions corresponding to each of the movements R 3 , R 1 , R 2 , D H , whereupon corresponding leaf spring assemblies  200   a,    200   b,    200   c,    200   d  hold the grip controller in the neutral positions until a sufficient operative force is applied. The grip controller  21  in thus maintained in the neutral position with a high reliability. 
         [0063]    By way of example,  FIGS. 9-21  illustrate an embodiment of the invention incorporating the spring-arm mechanisms  100  and the leaf spring assembly  200  for the respective movements of the grip controller  21 . 
         [0064]      FIG. 9  shows an exploded view of an assembly of the handle  22  as it connects with the upper housing  80  of the grip controller  21 . One end of the handle  22  comprises a coupling portion  56  fixedly connected to the handle so that a lateral tab  146   c  rotates with a rotation of the handle  22 . The coupling portion  56  attaches to a first end of shaft  52 . The shaft  52  passes through an upper rotatable part  64 , and a second end of the shaft  52  has a cavity  216   c  configured to cooperate with the V-shaped bend of a leaf spring  220   c.  The shaft extends through leaf spring housing  201   c  to engage with leaf spring  220   c  and further to connect with sensor  34   c.  A spring-arm mechanism, comprising pivot arms  110   c  and  120   c  connected by spring  130   c,  is provided between the upper rotatable part  64  and the coupling portion  56 , the lateral tab  146   c  fitting in between the pivot arms  110   c,    120   c.    
         [0065]      FIGS. 10   a  and  10   b  show a rear view and a frontal view, respectively, of the upper housing  80  of the control assembly wherein the handle  22  is in the neutral position.  FIGS. 11   a  and  11   b  show respective bottom and top views of the upper housing  80  wherein the handle  22  is in a biased position. In  FIGS. 10   b  and  11   b,  the sensor  34   c  is not shown to reveal the leaf spring housing  201   c,  leaf spring  220   c,  and cavity  216   c.    
         [0066]    In  FIGS. 9 ,  10   a - b,  and  11   a - b,  lateral tab  146   c  is fixed to coupling portion  56  to move with the coupling portion  56 . Lateral tab  148   c  is fixed to the upper rotatable part  64 . 
         [0067]    In  FIGS. 11   a  and  11   b,  an operative movement R 3  of the grip controller  21  about the axis A L  causes the lateral tab  146   c  to force the spring-arm  120   c  away from the spring-arm  110   c  that is held in place by lateral tab  148   c,  increasing the tension in spring  130   c  and forcing the V-shaped bend of the leaf spring  220   c  from the cavity  216   c.  When the operative force is released, the tension in the spring  130   c  urges the spring-arms  110   c  and  120   c  together, bringing the lateral tabs  146   c,    148   c  together and the handle  22  into the neutral position, whereupon the V-shaped bend of the leaf spring  220   c  enters the cavity  216   c.    
         [0068]    The other movements R 1 , R 2 , D H  of the grip controller  21  are regulated in a similar manner. 
         [0069]    For example,  FIGS. 12 and 13  illustrate two perspective exploded views of the assembly of the grip controller  21  rotatable about the second axis A 2 . A shaft  62  extends through the upper housing  80 , comprising the upper rotatable part  64  mounted upon an intermediate pivot part  65 . A first end of the shaft  62  engages with the spring-arms  110   b,    120   b.  The first lateral tab  146   b,  fixed to the upper rotatable part  64 , is configured to move with the second movement R 2  of the grip controller  21 , while the second lateral tab  148   b  is fixed to the intermediate pivot part  65 . Each of the lateral tabs  146   b,    148   b  are fitted between the spring-arms  110   b,    120   b.  The other end of the shaft  62  extends through the leaf spring housing  201   b  to engage with the sensor  34   b.    
         [0070]      FIGS. 14   a  and  14   b  show opposite side views of the assembly of  FIGS. 12 and 13  that pivots about the axis A 2 , wherein the grip controller  21  is in the neutral position. The first and second lateral tabs  146   b,    148   b  are aligned between the spring arms  110   b,    120   b.    
         [0071]      FIGS. 15   a  and  15   b  show opposite side views corresponding to  FIGS. 14   a  and  14   b,  wherein the grip controller  21  is in a biased position. An operative movement R 2  of the grip controller  21  about the axis A 2  causes the lateral tab  148   b  to force the spring-arm  120   b  away from the spring-arm  110   a  that is held in place by lateral tab  146   b,  increasing the tension in spring  130   b  and forcing the V-shaped bend of the leaf spring  220   b  from the cavity  216   b.  When the operative force is released, the tension in the spring  130   b  urges the spring-arms  110   b  and  120   b  together, bringing the lateral tabs  146   b,    148   b  together and the handle  22  into the neutral position as shown in  FIGS. 14   a  and  14   b,  whereupon the V-shaped bend of the leaf spring  220   b  enters the cavity  216   b.    
         [0072]      FIG. 16  shows an exploded view of an assembly of the grip controller  21  rotatable about the first axis A 1 . The intermediate pivot part  65  is fixedly connected to a base part  68  of the upper housing  80 . The base part  68  is rotatably attached to a lateral pivoting part  67 , the latter which will be further described later. A shaft  66  with a cavity  216   a  extends through each of the intermediate pivot part  65 , the base part  68 , and the lateral pivoting part  67 . The top end of the shaft  66  fits with the sensor  34   a.    
         [0073]    The base part  68  incorporates a leaf spring housing  201   a  configured to receive a leaf spring  220   a.  The base part  68  also provides a first lateral tab  146   a  configured to fit between spring arms  110   a,    120   a.  Spring arms  110   a,    120   a  are provided between the base part  68  and the lateral pivoting part  67 . 
         [0074]    The lateral pivoting part  67  provides a second lateral tab  148   a,  also configured to fit between spring arms  110   a,    120   a.  The shaft  66  is secured to the lateral pivoting part  67  with a washer  140   a  and a nut  142   a.    
         [0075]      FIGS. 17   a  and  17   b  show respective top and bottom views of the assembly of  FIG. 16  when in a neutral position. In the top view  FIG. 17   a  the sensor  34   a  is excluded so that the shaft  66 , cavity  216   a,  and leaf spring  220   a  are shown. In the bottom view  FIG. 17   b,  the lateral pivoting part  67  is illustrated with dotted lines to better illustrate the spring arms  110   a,    120   a  behind the lateral pivoting part  67 . 
         [0076]      FIGS. 18   a  and  18   b  correspond to  FIGS. 17   a  and  17   b  except that the assembly of  FIG. 16  is shown in a biased position. An operative movement R 1  of the grip controller  21  about the axis A 1  causes the lateral tab  148   a  to force the spring-arm  120   a  away from the spring-arm  110   a  that is held in place by lateral tab  146   a,  increasing the tension in spring  130   a  and forcing the V-shaped bend of the leaf spring  220   a  from the cavity  216   a.  When the operative force is released, the tension in the spring  130   a  urges the spring-arms  110   a  and  120   a  together, bringing the lateral tabs  146   a,    148   a  together and the handle  22  into the neutral position as shown in  FIGS. 17   a  and  17   b,  whereupon the V-shaped bend of the leaf spring  220   a  enters the cavity  216   a.    
         [0077]      FIG. 19  shows an exploded view of an assembly of the parallelogram mechanism  90 . The lateral pivoting part  67  is mounted upon two arms  91   a - b,  which in turn are each pivotably mounted to positions on a base  96 . One of the arms  91   a  is mounted to the lateral pivoting part  67  by way of a first shaft  72 , and the other arm  91   b  is mounted to the lateral pivoting part by way of a second shaft  91 . The second shaft  91  is secured by way of a washer  94  and a nut  95 . 
         [0078]    The first shaft  72  extends entirely through the lateral pivoting part  67 . One end of the first shaft  72  extends through a leaf spring housing  201   d  to connect with a sensor  34   d.  The other end of the first shaft  72  extends through spring arms  110   d,    120   d.  The spring arms  110   d,    120   d  are secured by way of a washer  140   d  and a nut  142   d.  First lateral tab  146   d  is provided on the first arm  91   a  for movement with a movement of the first arm  91   a.  Second lateral tab  148   d  is provided on the lateral pivoting part  67 . 
         [0079]      FIGS. 20   a  and  20   b  illustrate opposite side views of the parallelogram mechanism  90  of  FIG. 19 .  FIG. 20   a  faces the spring arms  110   d,    120   d,  and  FIG. 14   b  faces the leaf spring housing  201   d.  The first shaft  72  includes cavity  216   d  configured to fit with the V-shaped bend of leaf spring  220   d.  The spring arms  110   d,    120   d  enclose lateral tabs  146   d,    148   d.  As shown in  FIGS. 20   a  and  20   b,  the parallelogram mechanism  90  is in the neutral position. 
         [0080]      FIGS. 21   a  and  21   b  correspond respectively with  FIGS. 20   a  and  20   b  except that the parallelogram mechanism  90  is in a biased position. The first lateral tab  146   d  is configured to move with the first arm  91   a  in accordance with a movement D H  of the grip controller  21 . With said movement, the lateral tab  146   d  forces the spring-arm  120   d  away from the spring-arm  110   d,  increasing the tension in spring  130   d  and forcing the V-shaped bend of the leaf spring  220   d  from the cavity  216   d.  When the operative force in the horizontal direction D H  is released, the tension in the spring  130   d  urges the spring-arms  110   d  and  120   d  together, bringing the handle  22   d  into the neutral position shown in  FIGS. 20   a  and  20   b  whereupon the V-shaped bend of the leaf spring  220   d  enters the cavity  216   d.    
         [0081]    In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to one skilled in the art that these specific details are not required in order to practice the present invention. The invention as described herein may comprise one, several, all, or any of the embodiments provided above in any combination. The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto.