Abstract:
The low-bush berry harvester that has a plurality of interspaced berry-picking units movable along a closed-loop berry-picking path. The closed-loop berry picking path is non-circular, but rather designed with a relatively straight lower portion configured and adapted to be level with the ground during use. Hence, the berry-picking units are slidable against the ground in the straight lower portion of the berry-picking path to pick berries, and are pivotable in an upper portion of the berry-picking path to drop picked berries for collection.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of U.S. provisional application No. 60/908,486, entitled “Low-Bush Berry Harvester”, filed Mar. 28, 2007 by applicant, the contents of which are hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    The present specification generally relates to a harvester particularly adapted to harvesting low-bush berries such as low-bush blueberries, for example. 
       BACKGROUND 
       [0003]    During many past decades, the wild blueberry has been hand harvested with a metal rake similar to the cranberry scoop. Because harvesting the blueberry fruit constitutes one of the major expenses in producing the crop, there has been manifested interest in the last decade of reducing these costs by mechanical harvesting. 
         [0004]    One known mechanical blueberry harvester uses steel teeth combs on a rotating head. The frame is carried by a tractor. When the frame rotates, the combs rotationally travel in a circular motion. The combs progressing in the lower portion of the circle move in the rear direction, opposite the displacement of the tractor. While the harvester is displaced in a forward longitudinal direction of displacement over a blueberry field, the berry-picking combs successively engage blueberry bushes and pick the blueberries therefrom. The blueberries are eventually discharged onto a lateral, longitudinal conveyor, which takes them to the rear of the tractor, where they are discharged into baskets. 
         [0005]    Although this type of blueberry harvester has been found satisfactory to a certain degree, there remains room for improvements. 
       SUMMARY 
       [0006]    In accordance with one aspect, there is provided A low-bush berry harvester which has berry-picking units which are successively and cyclically slid against, or adjacent to, the ground, along a predetermined distance, in a substantially horizontal lower portion of a berry picking path, where they engage the low-bush berry bushes. Henceforth, the berry-picking path is non-circular, but has a substantially linear portion at a lower portion thereof along which the berry-picking units are slid against or near the ground. In one embodiment, the berry-picking units are carried by two laterally opposite chains which are wrapped around respective non-circular chain guides and driven by sprockets. Sliding the berry-picking units against, or adjacent to, the ground in the substantially horizontal lower portion of the berry-picking path can yield a better berry-picking efficiency than what was previously achieved by rotating berry-picking combs in a circular motion around a horizontal axis. 
         [0007]    In accordance with one aspect, there is provided a method for harvesting berries with a low-bush berry harvester that has a plurality of elongated berry-picking units, the method comprising: while moving the harvester in a longitudinal direction over the ground, simultaneously
       carrying the elongated berry-picking units cyclically around a non-cylindrical closed-loop berry-picking path having a relatively straight lower portion during which the berry-picking units are slid against the ground, thereby picking and collecting berries, and an upper portion,   maintaining the berry-picking units spaced apart from one another along the berry-picking path, and   rotating the berry-picking units around an axis lengthwise thereto, thereby dropping the collected berries, when the berry-picking units are being carried in the upper portion of the picking path.       
 
         [0011]    In accordance with another aspect, there is provided a low-bush berry harvesting system comprising a frame movable in a longitudinal direction, the frame having two transversally spaced-apart guiding sub-systems each carrying a respective closed driving loop, a plurality of elongated berry-picking units extending transversally between the two closed driving loops and each rotatably mounted to the closed driving loops at each opposite end thereof for rotation about a transversal axis, each berry-picking units having a corresponding comb for picking berries, the closed driving loops generally describing a closed-loop berry-picking path along which they can carry the rotation axes of the berry-picking units, the berry-picking path having a lower, relatively straight and horizontal portion, the berry-picking units being spaced apart from one another along the berry picking path, and a rotating sub-systems configured and adapted for rotating the berry-picking combs around the respective rotation axes thereof as they are being carried along the berry-picking path by the closed driving loops such that, during use of the system, the combs of the berry-picking comb units are maintained in a forward-facing, generally horizontal orientation along the relatively straight and horizontal portion of the berry-picking path to pick berries, and are at least partially rotated in an upper portion of the berry-picking path to empty the picked berries. 
         [0012]    In accordance with another aspect, there is provided a low-bush berry harvester that has a plurality of elongated berry-picking units interspaced and movable along a closed-loop berry-picking path, characterized in that the berry-picking path is non-circular and has a relatively straight lower portion in which the berry-picking units are slidable against the ground to pick berries, and in that the berry-picking units are partially rotated around a lengthwisely oriented axis, in an upper portion of the berry-picking path, to drop picked berries for collection. 
         [0013]    In accordance with another aspect, there is provided a low-bush berry harvester that has a plurality of interspaced berry-picking units cyclically carried along a closed-loop berry-picking path and each effecting one complete 360° rotation around a transversal axis thereof during each cycle, characterized in that the berry-picking units are pivotable along the transversal axis independently of their being carried along the berry-picking path, slidable against the ground to pick berries in a lower portion of the berry-picking path, and in that the rotation of the receptacles is concentrated in an upper portion of the berry-picking path, where picked berries are dropped from the receptacles and collected. 
         [0014]    In accordance with another aspect, there is provided a low-bush berry harvesting system comprising a frame movable in a longitudinal direction, the frame having two transversally spaced-apart chain guides each associated with respective sprockets, each chain guide and associated sprockets carrying a respective guide chain, a plurality of elongated berry-picking units extending transversally between the two chains and each rotatably mounted to the guide chains at each opposite end thereof for rotation about a transversal axis, the berry-picking units each having a comb portion for picking berries and a receptacle portion for supporting the picked berries during picking, the guide chains generally describing a closed-loop berry-picking path along which the rotation axes of the berry-picking units are carried, the berry-picking units being spaced apart from one another along the berry picking path, and rotation guides fixed to the frame configured and adapted to rotate the berry-picking combs by abutment thereagainst during use of the device as they are being carried along the berry-picking path by the guide chains, wherein, during use of the device, combs of the berry-picking units are maintained in a forward-facing generally horizontal orientation along a generally linear distance in a lower portion of the berry-picking path to pick berries and are partially rotated to empty the picked berries in an upper portion of the berry-picking path. 
         [0015]    In accordance with another aspect, there is provided A low-bush berry harvester for displacement in a longitudinal orientation, the harvester comprising a plurality of transversally-extending elongated berry-picking units rotatably mounted to two transversally opposite closed driving loops in an equally interspaced manner along the driving loops, the driving loops being guidingly mounted on a frame, each berry-picking unit having two opposite transversal ends bearing a respective rotational connection to a corresponding driving loop, a berry-picking portion longitudinally opposite a receptacle portion, a transversally-extending center of gravity axis offset from the rotational connections toward the receptacle portion, and a cam member transversally extending from one of the transversal ends along a cam axis offset from the rotational connections toward the receptacle portion, and a transversally-extending berry-receiving element positioned between the driving loops, the driving loops being capable of cyclically moving the receptacles along a closed berry-picking path having a lower portion where the receptacles are slid against the ground with the berry-picking portion facing a forward direction to collect low-bush berries, a front portion where the berry-picking units are successively raised from the ground while the cam member abuttingly slides along a first cam surface provided on the frame and which maintains the berry-picking portion generally oriented toward the front by limiting the pivoting of the receptacles under the action of gravity, an upper portion where the berry-picking units are carried into abutment against a second cam surface provided on the frame which pivots the receptacles to discharge collected berries onto the transversally-extending berry-receiving element and where the center of gravity axis is pivoted over and around the rotational connection, and a rear portion where the berry-picking units are lowered to the ground while the cam member abuttingly slides along a third cam surface provided on the frame and which maintains the berry-picker portion oriented toward the front by limiting the pivoting of the receptacles under the action of gravity prior to the receptacles landing against the ground. 
         [0016]    The harvester can be embodied as a unit for use carried by a vehicle such as a tractor, in the front or on the side thereof, and can be embodied as part of a specialized berry-picking vehicle. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0017]    Further features and advantages will become apparent from the following detailed description, taken in combination with the appended figures, in which: 
           [0018]      FIG. 1  is a schematic side elevation view of an example of an improved low-bush berry harvester in use, carried by a vehicle; 
           [0019]      FIG. 2  is a front perspective view of the blueberry harvester of  FIG. 1  with two berry-picking units removed; 
           [0020]      FIG. 3  is a perspective view showing one of the berry-picking units in greater detail; 
           [0021]      FIG. 4  is a perspective view showing a side plate of the blueberry harvester of  FIG. 1  without the berry-picking units; 
           [0022]      FIG. 5  is a view similar to  FIG. 4  with showing the position of the berry-picking units; 
           [0023]      FIG. 6  is a front elevation view, fragmented, showing the connection between a berry-picking unit and a side plate; and 
           [0024]      FIGS. 7A to 7D  are side elevation views showing successive positions of the berry-picking units along the berry-picking path. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows an example of a harvester  10 . In this example, the harvester  10  is specifically adapted for harvesting blueberries, and is provided as a unit carried by a tractor  12 . The tractor is moving in a longitudinal orientation  14  and carries the blueberry harvester  10  over blueberry bushes  16 . In this example, the blueberry harvester  10  is carried by a fork  20  of the tractor  12 . When picking wild blueberry bushes, it is preferable that the tractor  12  have flat tracks  22  instead of wheels, to reduce potential damage to the blueberry bushes  16  as the tractor  12  is displaced on them. The blueberry harvester  10  includes four berry-picking units  24 ,  25 ,  26 ,  27 , rotatably mounted between two closed driving loops defining a berry-picking path  32 . Henceforth, there are two main subsystems included in the harvester: two-spaced apart guiding subsystems which receive, carry, and guide the driving loops, and thereby determine the shape of the closed berry-picking path  32 ; and a rotation subsystem which controls the attitude of the berry-picking units  24 ,  25 ,  26 ,  27  as they travel along the berry-picking path  32  by controlling the rotation of the berry-picking units  24 ,  25 ,  26 ,  27  along their transversal rotation axes which are displaced along the berry-picking path  32 . In the illustrated embodiment, the driving loops are driven in a counter-clockwise orientation  30  to carry the berry-picking units  24 ,  25 ,  26 ,  27  along the berry-picking path  32 , thereby carrying the berry-picking units  24 ,  25 ,  26 ,  27  in a forward-facing direction as they are slid against the ground. In operation, picked blueberries  34  are dropped onto a transversal conveyor  36  where they are transversally carried and dropped onto a longitudinal conveyor  38 . The longitudinal conveyor  38  carries the picked berries to the rear of the vehicle  12  where they are placed into baskets  40 . 
         [0026]      FIG. 2  shows the blueberry harvester  10  in greater detail. In this example, the harvester  10  has a frame  42  with two opposite side plates  44 ,  46 . It will be noted that, in  FIG. 2 , two of the four berry-picking units have been removed to increase clarity. The two remaining berry-picking units  24 ,  27  are illustrated. In this example, the driving loops used to drive the berry-picking units  24 ,  27  are loop chains  28 ,  29 . The berry-picking units  24 ,  27  are rotatably mounted to the loop chains  28 ,  29  so as to be both rotatable around a transversal rotation axis  89  coinciding with the axis of a rotational connection  94  to the loop chain  28 , and displaceable to be carried along the berry-picking path  32  by the loop chains  28 ,  29 . The loop chains  28 ,  29  are mounted to the frame  42  via a guiding subsystem  18  which defines the shape of the path along which the rotation axes  89  of the berry-picking units  24 ,  27  are carried. In this embodiment, the guiding susbsystem  18  includes a plurality of chain guides and sprockets, the details of which will be described further below. A transversal conveyor  36  extends transversally between and through the two opposite side plates  44 ,  46 . Each berry-picking unit  24 ,  27  is similar. 
         [0027]    As best viewed in  FIG. 3 , the berry-picking unit  24  has a body  31  having a front berry-picking portion  48  having a berry-picking comb  49 , and a rear receptacle portion  50  generally shaped as an L and having a front flange  51  connected to the comb  49  and a rear flange  52  substantially perpendicular to the front flange  51 . A respective side member  33 ,  35  is provided on each side of the body  31 . The berry-picking unit  24  has two rotatable chain links  90 ,  71 , one at each opposite end thereof. Each chain link  90 ,  71  is affixed to an extension which is journaled in the respective side member  33 ,  35  of the berry-picking unit  24 , thereby providing respective rotational connections  94 ,  95  between the berry-picking unit  24  and the loop chains  29 ,  28  ( FIG. 2 ). The chain links  90 ,  71  are assembled to the loop chains  28 ,  29 , thereby providing means by which the berry-picking unit can be carried by the loop chains  28 ,  29 , whereas the rotational connections  94 ,  95  allow the berry-picking unit  24  to be rotated around a transversal rotation axis  89  independently of the direction in which it is carried by the loop chains  28 ,  29 . The center of gravity  45  of the berry-picking unit  24 , or more particularly the transversal axis  93  coinciding with the center of gravity of the berry-picking unit  24 , is offset from the transversal rotation axis  89  toward the rear. The rear end, or receptacle portion  50  of the berry-picking unit  24 , thereby tends to fall downwardly under the action of gravity when the berry-picking unit  24  is held at its rotational connections  94 ,  95 . As it will be discussed in greater detail below, this falling tendency of the berry-picking unit  24  is controlled and harnessed using camming surfaces associated with the frame  42  of the harvesting system, to maintain the combs  49  forwardly aligned along a given distance in the lower portion of the berry-picking path  32 , and to concentrate the rotation of the berry-picking units in an upper portion of the path  32 , over the transversal conveyor  36 , where it can empty the receptacle portions  50  from picked blueberries onto the transversal conveyor  36 . Toward the rear of the berry-picking unit  24 , two cam pins  75 ,  76  extend transversally therefrom along a cam axis  77 , the use of which will be described further below. The berry-picking units  24 ,  25 ,  26 ,  27  being essentially identical to one another, only one is described in detail. 
         [0028]      FIG. 4  shows the arrangement of the right side plate  46  in further detail. The two opposite side plates  44 ,  46  are essentially mirror images of one another and therefore only the right side plate  46  will be described in detail. The loop chain  29  is mounted around a plurality of chain guides  55 ,  56 ,  57  and sprockets  58 ,  59 ,  60 ,  61  which together form a guiding subsystem  19  defining the path of the loop chain  29 , and thereby a traveling path of the rotation axis  89  of the berry-picking unit  24 . The position of the chain links  71 ,  72 ,  73 ,  74  corresponding to the rotational connection  95  of each one of the berry-picking units  24 ,  25 ,  26 ,  27  is shown. In this example, there is absence of a chain guide in the lower portion  62  of the loop chain  29 , this affords the berry-picking units  24 ,  25 ,  26 ,  27  a certain vertical degree of freedom to adapt to bumps and other irregularities as they are slid against the ground. This feature is particularly useful for picking wild blueberries which are often on uneven terrain. In this embodiment, one of the sprockets is a drive sprocket  58  and the others are idle sprockets  59 ,  60 ,  61 . 
         [0029]    Referring back to  FIG. 2 , a drive motor  97  is geared with the drive sprocket  58  by means of a chain  98 . In this embodiment, the drive motor  97  is mounted to a drive shaft  54  which transversally extends across the two side plates  44 ,  46  of the harvester  10 . On the left side (not shown), the drive shaft  54  is also similarly geared with the corresponding drive sprocket by means of a chain, and both loop chains  28 ,  29  are thereby driven simultaneously. 
         [0030]    Referring to  FIG. 4 , a berry-picking unit rotation subsystem  53  is used to guide the rotation of the berry-picking units  24 ,  25 ,  26 ,  27  ( FIG. 2 ) as they are carried by the loop chain  29  along the berry-picking path  32 . In this embodiment, the rotation subsystem  53  includes: a front pin guide  63  having a first camming surface  64 ; an upper pin guide  65  provided in two parts, having a corresponding two-part camming surface  66  with a discontinuity  67  where it intersects the path of the loop chain  29  to allow passage of the rotational connection  95  of the berry-picking units  24 ,  25 ,  26 ,  27 ; and a rear pin guide  68  having a corresponding camming surface  69 , all of which are fixedly mounted to the side plate  46 . The camming surfaces  64 ,  66 ,  69  are engaged by the transversally extending cam pin  76 , and thereby control the attitude, or rotation, of the berry-picking receptacles. In this embodiment, a berry-picking unit body cam  70  is also used. The body cam  70  comes into abutment against a side member  35  of the body  31  of the berry-picking unit  24  to move the cam pin  75  ( FIG. 3 ) across the gap  67  in the upper pin guide  65 , against the falling tendency caused by gravity. The body cam  70  also forms part of the rotation subsystem and is mounted on the side plate  46 . 
         [0031]      FIG. 5  schematically illustrates the position of the berry-picking units  24 ,  25 ,  26 ,  27 , along the loop chain  29  which coincides with the berry-picking path  32 . The berry-picking units  24 ,  25 ,  26 ,  27  have a center of gravity  45  which is offset from the rotational connection  95  of the chain links  71 ,  72 ,  73 ,  74 . In this case, the center of gravity  45  is offset toward the rear, or receptacle portion  50 , of the berry-picking units  24 ,  25 ,  26 ,  27 . Therefore, when no external force is applied to the berry-picking units  24 ,  25 ,  26 ,  27 , the receptacle portion  50  tends to pivot about the rotation axis  71 ,  72 ,  73 ,  74  toward the ground due to the action of gravity. The cam pin  76  extends transversally at the rear portion  50 , and this pivoting tendency can be controlled with the pin guide camming surfaces  64 ,  66 ,  69  which provide support to the cam pin  76  during corresponding portions of the berry-picking path  32 . 
         [0032]    As can be understood more clearly from  FIG. 6 , there are thus three levels of interaction between the components on the side plate  44  and each berry-picking unit ( 24 ). A first level of interaction is between the berry-picking unit  24  and the loop chain  28 . The chain link  90  which forms part of the rotational connection  94  of the berry-picking unit  24  is shown assembled to the loop chain  28 . It is the loop chain  28  which carries the berry-picking unit  24  along the berry-picking path while the berry-picking unit  24  is free to rotate about the rotation axis  89 . The loop chain  28  is confined on the chain guides and sprockets within a first depth  78 . On the berry-picking unit  24 , only the chain link  90  extends into the first depth. 
         [0033]    A second level of interaction is between the berry-picking units and the pin guides  63 ,  65 ,  68  (only the upper pin guide  65  is shown in  FIG. 5 ). The pin guides  63 ,  65 ,  68  each have a camming surface  64 ,  66 ,  69  which extend inwardly from the side plate  46  and loop chain  28 , between the first depth  78  and a second depth  79 . In use, the camming surface  66  abuts against the cam pin  75  which extends transversally from the rear of the body  30  of the berry-picking unit  24  into the second depth  79 . The camming, or sliding abutment of the cam pin  75  against the camming surface  66  can exert a rotating force on the berry-picking unit  24  around the rotation axis  89 , which counteracts the rotating force which can result from gravity acting on the center of gravity of the unit  24 , thereby serving to control and harness the falling rotation tendency of the berry-picking unit  24 . 
         [0034]    A third level of interaction used in the present embodiment is between the unit body guide  70  which extends past the side plate  46 , the loop chain  28 , and the pin guides  63 ,  65 ,  68 , to a third depth  80 . The body  30  of the berry-picking unit extends into the third depth  80 . The body guide  70  can thus engage the body  30  of the berry-picking unit  24  directly. 
         [0035]    Henceforth, the berry-picking unit  24  is rotatably mounted loop chain  28  at the chain link  71 . The chain  28  is confined within at a first depth  78 . The cam pin  76  extends transversally from a transversal end  81  of the receptacle  24 . The cam pin  76  is shorter than the chain pin  71  and does not extend beyond the first depth  78 . The pin guide  65  extends from the side plate  46  up to a second depth  79  sufficient for it to abut against, and to slidingly receive, the cam pin  76 . The unit body cam  70  projects to a third depth  80  which is sufficient to engage the body  31 , or more particularly to a side member  33 , of the berry-picking unit  24  at one end  81  thereof. 
         [0036]      FIGS. 7A to 7D  schematically depict the harvester in operation by showing several successive positions of the berry-picking units  24 ,  25 ,  26 ,  27  being carried by the loop chain  28  in an equally interspaced fashion from one another. The berry-picking units  24 ,  25 ,  26 ,  27  are slid against the ground as they are pulled by the loop chain  28  in a lower portion  62  of the berry-picking path. When they reach a front portion of the lower portion  62  of the berry-picking path  32 , the cam pin  76  engages the camming surface  64  and the berry-picking unit  24  is raised by the loop chain  29  while the rear portion  50  of the berry-picking unit  24  is kept from pivoting by the cam pin  76  which abuts the camming surface  64 . When carried around to the front sprocket  61  ( FIG. 7B ), the rear portion  50  of the receptacle  26  tends to pivot downwardly but in this example, the center of gravity  45  is positioned in a manner that this is not sufficient for the berries to fall out from the receptacle portion  50 . As the chain link  71 , which connects the berry-picking unit  24 , is moved along an upper portion  81  of the berry-picking path  32 , the cam pin  76  engages the camming surface  66  of the upper pin guide  65 , which forces the receptacle  24  to partially rotate sufficiently to empty the berries onto the transversal conveyor  36 . The camming surface  66  then continues to pivot the berry-picking unit  26  up to a point where the center of gravity  45  of the receptacle  27  is toppled over the chain link  71  and toward the rear of the harvester, and then gravity continues the pivoting movement and the guide pin  76  engages the camming surface of the rear pin guide  68  (transition between  FIGS. 7A and 7B ). The rear pin guide  68  limits the pivoting of the receptacle  26  to position the receptacle in a proper angle, or attitude, for it to be correctly aligned when it is lowered to the ground ( FIGS. 7B to 7D ). It will be understood that the cam pin  76  transversally projects or extends a certain distance sufficient for it to engage the pin guides  63 ,  65 ,  68 , but not too much, to avoid interference with the chain loop  29 . The pivoting passage of the berry-picking unit  25  across the discontinuity  67  in the upper pin guide  65  (transition between  FIGS. 7B and 7C ) is assured in this case by the body cam  70  which abuts against the body  30  of the berry-picking unit  25 . The discontinuity  67  is present in the upper pin guide  65  to allow the chain link  72  and its rotational connection to pass through the upper pin guide  65  (transition between  FIGS. 7A and 7B ). Each berry-picking unit  24 ,  25 ,  26 ,  27  is thus slid against the ground a predetermined distance before being raised therefrom. 
         [0037]    For illustrative purposes, in the illustrated example of the blueberry harvester, the height of the harvester is of about 40 inches and the width is of about 50 inches, and the distance during which the receptacles are slid against the ground is of about 18 inches. Also as can be seen, the distance between the successive receptacles  24 ,  27  along the chain  29  is such that when one receptacle  24  begins to be raised by the chain  29 , a successive receptacle  27  is placed in position and ready to receive oncoming berry bushes (see  FIG. 7A ). 
         [0038]    In the illustrated embodiment, a comb brush  88  is used to free the berry picking comb  49  from remaining leaves or twigs which could have been picked up from the blueberry bushes as the berry-picking unit  24  passes across it. In this example, the brush  88  acts on the comb  49  while the receptacle  24  is upside down. In this embodiment, the brush  88  is rotatable and geared to the drive shaft  54 , though a non-rotary brush can alternately be used. The brush may be omitted in certain embodiments. 
         [0039]    As it can be seen therefore, in comparison to the prior art discussed above, in the improved blueberry harvester, the berry-picking combs do a 360° rotation for each cycle, but in this case, the berry-picking units are rotatably mounted to a driving loop which allows to slide the receptacles and the berry-picking units against the ground in a lower portion of the berry-picking path and to concentrate most of the 360° rotation of the berry-picking units in an upper portion of the berry-picking path, where blueberries can be emptied from the berry-picking units. 
         [0040]    In this example, the drive motor  97  can be a variable speed motor. In use, when the harvester  10  is being carried by a tractor  12 , as shown in  FIG. 1 , the tractor operator can thus vary the speed of tractor in the longitudinal direction  14 , and can also vary the speed at which the berry-picking units  24 .  25 ,  26 ,  27  travel along the berry picking path  32 . The speed at which the berry-picking unit  24  is slid against the ground is the sum of the speed of the tractor  12 , and the speed imparted to the berry-picking unit  24  along the berry picking path  32  by the driving loops  28 . Depending on the density of blueberries on the field, the speed of the tractor can thus be adjusted while maintaining the speed at which the berry-picking unit  24  is slid against the ground by adjusting the speed of the variable speed drive motor  84  of the driving loops  28 . Typically, the travelling speed of the loop chains  28  is adjusted first, and the speed of the carrying vehicle is then adjusted. 
         [0041]    The tractor  12  which is used to carry the harvester  10  can advantageously have an operator cabin configured and adapted to allow the operator to have visual access to the berry-picking unit  24  being slid against the ground in the lower portion of the berry-picking path. He can thus visually witness the rate at which the berry-picking unit  24  is being filled by blueberries and adjust the speed of the tractor and of the drive motor accordingly. For instance, if the field has a low density of blueberries, the operator can slow down or even stop the drive motor  97  of the berry-picking units, and increase the vehicle speed to enhance berry-picking efficiency. The same berry-picking unit  24  can thus be slid against the ground until it is satisfyingly filled with berries, which can advantageously minimize the amount of manipulation of the berries, instead of successively using two or more only partly filled berry-picking units. When the berry field has a high concentration of berries, the operator can lower the speed of the vehicle, and increase the speed of the berry-picking units  24 ,  25 ,  26 ,  27  along the berry-picking path  32  until the berry-picking units are each successively filled with a satisfactory amount of berries, and not too many berries, which could result in spillage of berries. 
         [0042]    In the example illustrated, the blueberry harvester  10  is particularly adapted to be carried by a vehicle such as a tractor, as illustrated in  FIG. 1 . However, it will be understood that in alternate embodiments, the harvester can be made a size allowing it to be manually displaced and mounted on wheels, similarly to a snow-blower, for example. Alternately, the drive loops can be geared to the rotation of the wheels and the drive motor can be omitted. The harvester can also be made part of a vehicle in alternate embodiments. 
         [0043]    Using the transversal conveyor allows to continuously remove the blueberries which are dropped thereon. However, in alternate embodiments, it can be suitable to omit the transversal conveyor and to position a blueberry container at a similar location instead. 
         [0044]    In alternate embodiments, the rotation subsystem described above can be replaced with alternate means to control the rotation of the berry-picking units. For example, the in an alternate embodiment, the berry-picking units can have integrated motors to drive the rotation at predetermined locations on the berry-picking path. 
         [0045]    In the illustrated example, the driving loops which carry the berry-picking units are loop chains, which advantageously present low-elasticity and sturdiness advantageous in this application. However it will be understood that the drive loop can alternately be a toothed belt or another equivalent. Concerning the guiding subsystem which is used to guide the loop chains in the above-described embodiment, it will be understood that different shapes and configurations of guides and/or sprockets can be used in alternate embodiments. A different guiding subsystem can be used to adapt to a different driving loop, for example. The particular shape of the berry-picking path can also vary in alternate embodiments. 
         [0046]    The berry harvester  10  illustrated is particularly well suited for picking low bush blueberries, however it will be understood that it can be adapted to pick other types of low bush berries, such as cranberries for example. In the example given above, a cam pin acts as a cam member of the berry-picking unit which engages camming surfaces of the pin guides. This configuration can be modified and equivalents to a cam pin can be used. 
         [0047]    In the example given above, four berry-picking units are used and equally interspaced along the chain guides. Equally interspacing along the chain guide is not an absolute requirement, there can be some range of tolerance in the relative interspacings. Also, more or less than four berry-picking units can be used. Using four berry-picking units in the configuration illustrated allows the berry-picking units to be sufficiently interspaced to be free from interference with one another during the various rotation stages of the berry-picking path, and to be sufficiently close to one another for a subsequent berry-picking unit to be readied against the ground as a previous berry-picking unit is beginning to be raised. 
         [0048]    Concerning the berry-picking units themselves, in alternate embodiments, the relative positions of the rotation axis, center of gravity axis, and cam pin axis can vary. 
         [0049]    As can be seen therefore, the examples described above and illustrated are intended to be exemplary only. The scope of the invention(s) is intended to be determined solely by the appended claims.