Patent Publication Number: US-6340278-B1

Title: Granule transfer apparatus and granule spreading method

Description:
TECHNICAL FIELD 
     The present invention relates to an improvement of a granule transfer apparatus and a granule spreading method, used to transport and place fresh concrete for dams, building structures, etc., transport and spread mortar, or transport and spread earth and sand for reclamation. 
     BACKGROUND ART 
     A transfer apparatus for fresh concrete or the like, which comprises a tower mast, a stage, a boom body formed of two or more boom components, etc., is a generally known apparatus described in an international application (WO96/16242) that is subjected to international publication, for example. 
     Referring now to FIG. 17, there will be described an outline of this conventional concrete transfer apparatus. 
     A tower mast TM contains therein a vessel-shaped carrier CV for pulling up fresh concrete F (concrete not hardened) from a concrete plant or the like onto an elevator body portion EL through the space under the tower mast TM. The vessel-shaped carrier CV is pulled up by means of a lift winch  171  with the aid of a wire rope  170 . The lift winch  171  is fixed to a stage body portion  172  that constitutes the elevator body portion EL. 
     Supported on the stage body portion  172  is a boom body portion, which is formed of a first boom component C′ and a second boom component C″. 
     The fresh concrete, pulled up to the upper part of the tower mast TM by means of the vessel-shaped carrier CV, is fed onto a conveyor for fresh concrete transportation (belt conveyor G′), which is provided on the first boom component C′ on the stage body portion  172 , via fresh concrete delivery means  173  and  173 ′. 
     The proximal end of the second boom component C″ is connected to the distal end of the first boom component C′, and these boom components C′ and C″ are arranged continuous with each other, in front and in rear, on a straight line. The first boom component C′ is provided with pulleys  174  and  175  on its opposite ends, individually, and the first belt conveyor G′ is stretched between the pulleys  174  and  175 . The first belt conveyor G′ is driven by a belt conveyor drive motor  176  that is placed on the first boom component C′. The second boom component C″ is provided with pulleys  177  and  178  on its opposite ends, individually, and a second belt conveyor G″ is stretched between the pulleys  177  and  178 . The second belt conveyor G″ is driven by a belt conveyor drive motor  179  that is placed on the second boom component C″. 
     The fresh concrete F, which is fed onto the first belt conveyor G′ via the fresh concrete delivery means  173  and  173 ′, is transported away from the stage body portion  172  by the first belt conveyor G′ and delivered onto the second belt conveyor G″. The fresh concrete on the second belt conveyor G″ is further transported away from the first belt conveyor G′ and dropped onto the ground through the distal end of the second belt conveyor G″. 
     An upper lift frame  180  is fixed to the stage body portion  172 , while a lower lift frame  182  is fixed to a mast frame  181  of the tower mast TM. A hydraulic cylinder  183  is interposed between the upper and lower lift frames  180  and  182  so that the upper lift frame  180  or the stage body portion  172  can be lifted or lowered with respect to the lower lift frame  182  or the tower mast TM. 
     The first boom component C′ can be turned on a substantially horizontal plane with respect to the stage body portion  172  by means of a boom turning device  184 . Further, the drawn-up length of the second boom component C″ from the first boom component C′ is adjustable so that the overall transportation length that combines the first and second belt conveyors G′ and G″ can be changed. Accordingly, the point on which the fresh concrete drops through the distal end of the second belt conveyor G″ is settled depending on the angle of turn of the first boom component C′ (and second boom component C″) with respect to the stage body portion  72  and the drawn-up length of the second boom component C″ from the first boom component C′. 
     If the drawn-up length of the second boom component C″ from the first boom component C′ is reduced, however, the position of the distal end of the second belt conveyor G″, from which the fresh concrete drops, gets nearer to the tower mast TM, but, it never gets beyond the position of the distal end of the first boom component C′ as it approaches the tower mast TM. Thus, the fresh concrete cannot be dropped on any region near the tower mast TM by only making a combination of the first and second boom components C′ and C″ turnable on a substantially horizontal plane with respect to the stage body portion  172  and making the substantial length of the combination of the first and second boom components C′ and C″ changeable. 
     To solve this problem, a tripper device H is provided on the first boom component C′ so as to be movable with respect to the first boom component C′. The tripper device H enables the fresh concrete, delivered thereto by means of the first belt conveyor G′ on the first boom component C′, to be taken out sideways and dropped on the way. If the tripper device H is situated on the distal end of the first boom component C′, the fresh concrete delivered thereto by means of the first belt conveyor G′ is fed onto the second belt conveyor G″ on the second boom component C″ without being taken out sideways. Accordingly, the point on which the fresh concrete drops from the tripper device H is settled depending on the angle of turn of the first boom component C′ with respect to the stage body portion  172  and the position of the tripper device H on the first boom component C′. 
     Thus, the conventional fresh concrete transfer apparatus shown in FIG. 17 has the following problems. 
     (1) Since the first and second boom components C′ and C″ turn on the horizontal plane with respect to the stage body portion  172  in a manner such that they are arranged continuous with each other, in front and in rear, on a straight line. It is necessary, therefore, to secure a wide area around the tower mast TM that is free from obstacles. 
     (2) The fresh concrete can be dropped in zigzags onto the ground by gradually moving in the distal end of the second boom component C″ in the dropping position or the tripper device H on the first boom component C′ in a certain direction while alternatingly turning the stage body portion  172  itself that is fitted with the first and second boom components C′ and C″. However, the heavyweight structure that includes the first and second boom components C′ and C″ and the stage body portion  172  has a great inertial mass, so that there is a problem on response when its movement is controlled for fine operation, in particular. 
     (3) Further, the structure in which the second boom component C″ is connected to the distal end of the first boom component C′ in a straight line requires the structure of the second boom component C″ to be designed for lighter weight. Accordingly, the second boom component C″ or the junction between the first and second boom components C′ and C″ is liable to suffer a problem in rigidity. 
     In order to solve this problem, the boom on the distal end side (second boom component C″) may be suspended from the tower mast TM in a manner such that one and the other ends of a suspension rope are fixed to the boom on the distal end side and the upper part of the tower mast TM, respectively. Since the boom components are contractible as mentioned before, however, the length of the suspension rope cannot be fixed. It is necessary, therefore, to change the length of the suspension rope as the boom is extended or contracted or give up attaching the suspension rope itself. Inevitably, the former arrangement requires use of a winch or other equipment that entails a complicated construction. If the attachment of the suspension rope is given up, on the other hand, the problem on rigidity cannot be solved. 
     (4) Further, the connected boom components are restricted in number by the aforesaid structural problem. Practically, the number of connectable boom components is limited to two (first and second boom components C′ and C″) , as shown in FIG.  17 . In the case where the combined boom in its minimum-length state is not very short and if the transfer apparatus is located in a narrow space, the mobility of the apparatus is restricted substantially. 
     (4) In the case where the combined boom body is supported on the tower mast that is built on the ground, moreover, the fresh concrete or the like can be spread and placed only in the region around the tower mast. 
     DISCLOSURE OF THE INVENTION 
     The object of the present invention is to provide a granule transfer apparatus and a granule spreading method utilizing the granule transfer apparatus, which eliminate the aforementioned drawbacks of the prior art, and in which granule can be spread around a boom body supporting portion, such as a tower mast, without use of a tripper device, the granule can be spread without shifting the location of the boom body supporting portion such as the tower mast even in case there are any obstacles between a target position for spreading operation and the boom body supporting portion such as the tower mast, weaving operation can be smoothly effected in various directions, the rigidity of a boom component on the distal end side and its junction can be secured satisfactorily, and a boom body can be designed so that its minimum-state length is shorter than that for the conventional apparatus. 
     Further, the boom body supporting portion is attached to a traveling body, such as a vehicle or vessel, so that a granule spreading region can be selected freely. 
     In order to achieve the above object, a granule transfer apparatus according to the present invention is a granule transfer apparatus that comprises a boom body formed of two or more connected boom components each including transfer means for transferring granule, a boom body supporting portion for rotatably mounting a stage having the boom body, stage turning means for turning the stage relatively to the boom body supporting portion, and granule delivery means provided on the stage and serving to deliver the granule to the transfer means of the boom component situated nearest to the stage. The granule transfer apparatus further comprises a pivotal portion located between the two connected boom components and serving to connect the basal part of the next boom component to the distal end portion of the boom component on the stage side, boom turning means for turning the next boom component with respect to the stage-side boom component, and junction granule delivery means for delivering the granule from the transfer means of the stage-side boom component to the transfer means of the next boom component. 
     In an aspect of a granule spreading method according to the present invention using one such granule transfer apparatus, an operational movement program to order the position of the boom body end and a rectilinear or arcuate movement between positions is previously taught, and the controller is caused to drive the transfer means to move the boom body end along a movement path given by the taught program and spread the granule while throwing out the granule through the boom body end, in accordance with the taught program. 
     In another aspect of the granule spreading method, the control means is previously caused to set and store a movement pattern for the boom body end, a granule spreading region is set as an input in the control means to move the boom body end into the granule spreading region, and the transfer means is then driven to move the boom body end in the set granule spreading region, thereby automatically spreading the granule, in accordance with the set movement pattern, while the granule is being thrown out through the boom body end. 
     According to the granule transfer apparatus of the present invention and the granule spreading method using this granule transfer apparatus, fixed-position rotation of the stage and turning motion of each boom component are combined so that the granule can be spread all over the peripheral region of the boom component supporting portion (tower mast and traveling body), so that boom components need not be provided with a tripper device thereon. Thus, the construction of the granule transfer apparatus is simplified, so that the general manufacturing cost is reduced. As the weight is reduced, moreover, the rigidity and strength of the boom body are improved relatively. 
     Moreover, the angle of turn of the stage and the angle of turn of each boom component can be adjusted without changing the target spreading position for the granule. If there are any obstacles between the boom body supporting portion, such as the tower mast, and the target spreading position, therefore, the granule spreading operation can be carried out without making any large-scale rearrangement, such as relocation of the boom body supporting portion such as the tower mast. 
     Further, tamping operation based on weaving can be carried out with only the boom component in the leading position rocked bit by bit. Therefore, the tamping operation can be effected more quickly and smoothly than in the case of the conventional apparatus in which the weaving operation is performed by continuously extending and contracting the continuous boom body on a straight line or by alternatingly turning the stage bit by bit. Since the granule can be automatically spread over the set granule spreading region in accordance with the taught pattern, the tamping operation can be carried out easily. Furthermore, the granule can be automatically spread along a taught granule spreading path. 
     Since the substantial lengths of the boom components are subject to no change, moreover, the strength of each boom component and its pivotal portion can be secured with use of a very simple structure including a suspension rope, mast, etc., and the rigidity of the whole boom body can be improved. Furthermore, the rigidity can be secured without increasing the weight or complicating the construction. If the same rigidity of the boom body as in the conventional case is required ultimately, therefore, the boom body can be dividedly composed of more boom components and can be designed so that its minimum-state length is shorter than that for the conventional apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a plan view of a granule transfer apparatus according to a first embodiment of the present invention; 
     FIG. 1B is a side view of the granule transfer apparatus shown in FIG. 1A; 
     FIG. 2A is a side view (partially in section) showing the way boom components of the granule transfer apparatus of FIGS. 1A and 1B are pivotally mounted and an arrangement of granule transfer means of each boom component; 
     FIG. 2B is a front view of the granule transfer apparatus shown in FIG. 2A; 
     FIG. 3 is a view (partially in section) of the granule transfer apparatus of FIGS. 1A and 1B, showing the engagement between a tower mast, stage, and stage base and taken from above the top side of the stage; 
     FIG. 4 is a sectional view of the granule transfer apparatus of FIGS. 1A and 1B, showing the engagement between the tower mast, stage, and stage base and taken along the center plane of the tower mast; 
     FIG. 5 is view showing a portion taken in the direction of arrow B of FIG. 3; 
     FIG. 6 is view showing a portion taken in the direction of arrow C of FIG. 3; 
     FIG. 7 is view showing a portion taken in the direction of arrow D of FIG. 3; 
     FIG. 8 is a side view of a granule transfer apparatus according to a second embodiment of the present invention; 
     FIG. 9 is a plan view of the granule transfer apparatus of FIG. 8; 
     FIG. 10 is a block diagram of a controller used in common in the first and second embodiments of the present invention; 
     FIG. 11 is a flowchart showing manual processing the controller of FIG. 10 executes; 
     FIG. 12 is a flowchart showing semiautomatic processing the controller of FIG. 10 executes; 
     FIG. 13 is a flowchart showing automatic processing the controller of FIG. 10 executes; 
     FIG. 14A is a flowchart showing processing of a pattern A executed in the automatic processing of FIG. 13; 
     FIG. 14B is a flowchart showing processing of a pattern B executed in the automatic processing of FIG. 13; 
     FIG. 15A is a flowchart showing processing of a pattern E executed in the automatic processing of FIG. 13; 
     FIG. 15B is a flowchart showing processing of a pattern E executed in the automatic processing of FIG. 13; 
     FIG. 16 is a diagram for illustrating the individual patterns handled in the automatic processing of FIG. 13; and 
     FIG. 17 is a side view of a prior art granule transfer apparatus. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     (Granule transfer apparatus according to first embodiment) 
     A granule transfer apparatus according to a first embodiment of the present invention will be described with reference to FIG. 1A (plan view) and FIG. 1B (side view). 
     A granule transfer apparatus  1  generally comprises a tower mast  2  (that constitutes a boom body supporting portion), a stage  3 , and a boom body  4 . The tower mast  2  is formed of a prism-shaped steel-frame structure, and has therein granule transfer means, i.e., a bucket elevator, for heaving up fresh concrete, mortar, or earth and sand (those substances to be transported will hereinafter be referred to generically as “granule”) from a concrete plant or the like onto the stage  3 . 
     Transportation buckets  5  and  6 , which constitute the bucket elevator, are vertically driven by winches  9  and  10  with the aid of wires  7  and  8 , respectively, and reciprocate between the basal part of the tower mast  2  and the stage  3 , thereby lifting the granule, delivered from a cart (not shown) in the concrete plant at the basal part of the tower mast  2 , to the height of the stage  3 . 
     The transportation buckets  5  and  6 , which has been moved to the stage  3 , discharge the granule into chutes  11  and  12 , whereupon the granule is delivered to granule transfer means of a first boom component  15 , i.e., a belt conveyor  16  (FIG.  2 B), which is situated nearest to the stage  3 , through a screw feeder  13  with a hopper, for use as granule delivery means, and a pressure-feed path  14 . 
     Numeral  17  denotes a counterweight, and  18  denotes a truss structure for maintaining the rigidity of the first boom component  15 . The stage  3 , which is mounted on a stage base  19 , can be finely adjusted in vertical position by extending or contracting a plurality of hydraulic cylinders  20  attached to a supporter  21  that is fixed to the tower mast  2 . Numeral  100  denotes a controller for controlling the granule transfer apparatus. 
     The above-described apparatus is constructed in the same manner as conventional granule transfer apparatuses (e.g., fresh concrete transfer apparatus disclosed in Japanese Patent Application KOKAI No. 8-209937 mentioned before). 
     Referring now to FIGS. 3 to  7 , there will be described a turning mechanism for the stage  3 . 
     FIG. 3 is a plan view (partially perspective) taken from above the top side of the stage  3  and schematically showing the engagement between the tower mast  2 , stage  3 , and stage base  19 . FIG. 4 is a sectional view taken along the center plane of the tower mast  2  and schematically showing the engagement between the tower mast  2 , stage  3 , and stage base  19 . 
     The stage base  19  is bored with a rectangular hole in its central portion, having a shape and size such that the prism-shaped tower mast  2  can be freely passed through it. The stage base  19  is mounted on the tower mast  2  so as to be vertically movable and nonrotatable. Besides, the stage base  19  is supported on the supporter  21  by means of the hydraulic cylinders  20  that are arranged side by side on the supporter  21  (see FIG.  1 B). 
     The stage base  19  has a generally disk-shaped external shape, and a large-diameter portion  22  and a small-diameter portion  23  are arranged on its outer peripheral portion, as shown in FIG. 4. A channel-shaped peripheral groove is formed on the outer periphery of the large-diameter portion  22 , opening outward in the radial direction thereof. An outer peripheral gear is formed on the outside of the large-diameter portion  22  by driving a large number of pins  24  into the peripheral groove so that the pins are arranged at given pitches in the vertical direction on a concentric circle (see FIG.  3 ). 
     A rail  25  is fixed to the top surface of the stage base  19  by means of a large number of clips  26  so as to form a circumferential track (see FIG.  3 ). The rail  25  bears thereon the load of the stage  3  that is rotatably placed on the stage base  19 . 
     Further, a through hole  27  having a diameter a little longer than the diagonal line of a plane section of the tower mast  2  is bored through the central portion of the stage  3  (see FIG.  3 ). The stage  3  is placed on the stage base  19  for fixed-position rotation with respect to the tower mast  2  and the stage base  19 . 
     More specifically, as shown in FIG. 3, four casters  28  are arranged at regular pitches of 90° on the circumference of a circle on the undersurface of the stage  3 , along the circumferential track of the rail  25  on the stage base  19 . The stage  3  is placed on the rail  25  by means of the four casters  28 . 
     Referring now to FIG. 6 taken in the direction of arrow C of FIG. 3, there will be described the engagement between the casters  28  fixed to the stage  3  and the rail  25  fixed on the stage base  19 . 
     As shown in FIG. 6, each caster  28  is composed of two rollers  29 , a roller receiving member  30  holding the rollers for rotation, and a stay  31  for fixing the roller receiving member  30  to the undersurface of the stage  3 . In order to secure the grounding performance of the two rollers  29  on the rail  25 , the roller receiving member  30  is mounted on the stay  31  by means of a pin  32  so that it can rock in some measure. In order to avoid unnecessary friction with the rail  25 , moreover, the two rollers  29  are rotatably mounted on the roller receiving member  30  in a manner such that the center line of its axis of rotation is in line with a normal to the track of the rail  25 , as shown in FIG.  3 . The stay  31  is fixed to the undersurface of the stage  3  by welding or other means. 
     While the stage  3  is placed on the stage base  19  for fixed-position rotation by means of the casters  28  and the rail  25 , in this arrangement, the casters  28  should further be prevented from running off the rail  25  inward or outward. 
     In the present embodiment, as shown in FIG. 3, therefore, four track regulating rollers  33 , which externally touch the small-diameter portion  23  of the stage base  19 , are rotatably arranged at regular pitches of 90° on the circumference of a circle on the undersurface of the stage  3 , whereby horizontal dislocation of the stage  3  on the stage base  19  or derailment of the casters  28  can be prevented. 
     Referring now to FIG. 7 taken in the direction of arrow D of FIG. 3, there will be described the way the track regulating rollers  33  are mounted on the stage  3  and the engagement between the track regulating rollers  33  and the small-diameter portion  23 . 
     As shown in FIG. 7, a prism-shaped stay  34  extends downward from the undersurface of the stage  3 . A second stay  35  extends horizontally from the lower end portion of the stay  34  toward the small-diameter portion  23  of the stage base  19 . The aforesaid track regulating roller  33  is rotatably supported on the distal end portion of the second stay  35 . The track regulating roller  33  is in sliding contact with the small-diameter portion  23  of the stage base  19 . As shown in FIG. 3, the four track regulating roller  33  are arranged so as to hold the small-diameter portion  23  of the stage base  19  between them from outside in the diametrical direction, each two opposite ones forming a pair. Accordingly, the horizontal position of the stage  3  relative to the stage base  19  is regulated completely, so that the casters  28  can never be disengaged from the rail  25  on the stage base  19  even when the stage  3  makes a fixed-position rotation. 
     The stage  3  and the various means arranged on the stage  3  are designed so that the center of gravity of the whole structure is situated in the center of the stage  3  by means of the counterweight  17 . Basically, therefore, the balance and safety of the stage  3  can be secured by only placing the stage  3  for fixed-position rotation on the stage base  19  and preventing positional deviation in the horizontal direction. In order to cope with abnormal vibrations attributable to natural disasters and the like, according to the present embodiment, however, a substantially L-shaped third stay  36  is further fixed to the lower end of the aforesaid stay  34 , as shown in FIG.  7 . Thus, the stage base  19  is held between the roller  29  of each caster  28  and the top surface of the distal end portion of the third stay  36 , whereby the stage  3  is prevented from fluctuating. There is a certain gap between the undersurface of the stage base  19  and the top surface of the distal end portion of the third stay  36 , so that the distal end portion of the third stay  36  can never come into contact with the undersurface of the stage base  19  as the stage  3  makes an ordinary fixed-position rotation. 
     As shown in FIG. 3, means for the fixed-position rotation of the stage  3  on the tower mast  2  and the stage base  19  is composed of a servomotor  37  and a speed reducer  38  fixed on the stage  3 , a pinion  40  fixed to the distal end of an output shaft  39  of the speed reducer  38 , etc. 
     Mounted on the output shaft of the servomotor  37  is a detector (not shown), such as a pulse coder, for detecting the rotational speed and rotational position of the servomotor  37 , thereby detecting the turn position of the stage  3  that is driven by the servomotor  37 . This detector may alternatively be mounted on the output shaft  39  of the speed reducer. 
     FIG. 5 shows the principal part of a portion corresponding to arrow B of FIG.  3 . As shown in FIG. 5, the output shaft  39  of the speed reducer  38  projects from the back surface of the stage  3 . The pinion  40  that is fixed to the distal end portion of the output shaft  39  is in mesh with the pins  24  (i.e., modules of the outer peripheral gear formed on the large-diameter portion  22  of the stage base  19 ) driven in the large-diameter portion  22  of the stage base  19 . 
     Thus, the stage  3  can be turned around the tower mast  2  and the stage base  19  by driving the servomotor  37  to rotate the pinion  40  through the medium of the speed reducer  38  and the output shaft  39 . 
     Referring now to FIGS. 1A,  1 B and  3 , there will be described the construction of the boom body  4  that is attached to the stage  3 . 
     As shown in FIGS. 1A and 1B, the boom body  4  according to the present embodiment is a three-stage boom that is composed of the first boom component  15 , which is situated nearest to the stage  3 , a second boom component  41  continuous with the distal end of the first boom component  15 , and a third boom component  42  continuous with the distal end of the second boom component  41 . 
     As shown in FIGS. 1B and 3, the first boom component  15 , which is situated nearest to the stage  3 , is attached to one side of the stage  3  by means of a pin  43 , and is supported diagonally from above by means of the aforesaid truss structure  18  that is set up on the stage  3 , whereby its rigidity is maintained. 
     The following is a description of the details of the construction of a pivotal portion between “a stage-side boom component” and “the next boom component” continuous with the former boom component and the construction of the belt conveyor that constitutes the independent granule transfer means for each boom component, taking the case of the relation between the first boom component  15  on the stage side and the next or second boom component  41 . 
     In the relation between the second and third boom components  41  and  42 , the second boom component  41  is the stage-side boom component, and the third boom component  42  is the next boom component remoter from the stage (and at the same time, the boom component in the leading position). The pivotal portion between the second and third boom components  41  and  42  and the belt conveyor for each boom component are constructed in the same manner as in the case of the relation between the first and second boom components  15  and  41 . 
     FIGS. 2A and 2B are perspective views showing the way the first and second boom components  15  and  41  are pivotally mounted and the constructions of belt conveyors  16  and  44  that constitute the granule transfer means for the first and second boom components  15  and  41 . FIG. 2A is a side view showing these components, and FIG. 2B is a front view. 
     As shown in FIG. 2A, an inner ring  46  of an external-tooth turntable bearing  45  is fixed to the undersurface of the distal end portion of the first boom component  15 , which is the stage-side boom component, by means of a stay  47 , while an outer ring  48  of the external-tooth turntable bearing  45  is fixed to the top surface of the proximal portion of the second boom component  41 , which is the next boom component, by means of a stay  49 . 
     As is generally known, the external-tooth turntable bearing  45  is composed of the inner and outer rings  46  and  48  and rollers  50  interposed between the inner and outer rings  46  and  48 . The inner and outer rings  46  and  48  are constructed so as to be relatively rotatable and immovable in the thrust direction. The inner ring  46 , which is formed of an annular body, is formed with a hole  51 . An external gear module  52  is formed on the outer peripheral portion of the outer ring  48  throughout the circumference. Thus, the second boom component  41 , which is the next boom component that is continuous with the stage-side boom component (that is, the first boom component  15 ), is rotatably mounted on the first boom component  15  by means of the external-tooth turntable bearing  45 , and the external-tooth turntable bearing  45  constitutes the pivotal portion between the first and second boom components  15  and  41 . 
     Further, a turning mechanism for turning the next or second boom component  41  with respect to the first boom component  15  on the stage side comprises a module  52  formed on the outer peripheral portion of the outer ring  48  of the external-tooth turntable bearing  45 , a motor (e.g., servomotor)  53  fixed to the distal end of the first boom component  15  and controllable in position and speed, and a pinion  54  fixed to the distal end of the motor shaft of the motor  53  and in mesh with the module  52 . 
     In short, the second boom component  41 , which is fixed to the outer ring  48 , is turned with respect to the first boom component  15  by driving the motor  53  to rotate the pinion  54 , thereby rotating the outer ring  48  around the inner ring  4  of the external-tooth turntable bearing  45 . 
     Mounted on the motor shaft of the motor  53 , moreover, is a detector (not shown), such as a pulse coder, for detecting the rotational speed and rotational position of the motor  53 . This detector can detect the turning speed and turning position of the second boom component  41  that is turned with respect to the first boom component  15 . 
     Further, a hopper  55 , which is fixed to the distal end portion of the first boom component  15 , extends downward through a through hole  51  in the central portion of the inner ring  46  of the external-tooth turntable bearing  45 , and constitutes granule delivery means at the junction between the first and second boom components  15  and  41 . 
     The belt conveyor  16  on the side of the first boom component  15  is driven by a motor  56  fixed on the first boom component  15  with the aid of a chain  57 , receives the granule discharged from the pressure-feed path  14  (see FIG. 1B) on the side of the stage  3 , transports it in the horizontal direction, and discharges it into the hopper  55  that constitutes the granule delivery means at the junction. Further, the granule dropped through the hopper  55  is received by he belt conveyor  44  on the side of the second boom component  41 , and is transported in the same manner as in the case of the belt conveyor  16 . 
     As shown in FIG. 2B, rollers  58  that support the top side of the belt conveyors  16  and  44  are divided in three in the width direction of the belt conveyors  16  and  44 , and the belt conveyors  16  and  44  are bent to project downward by means of the load of the granule so that the granule can be prevented from dropping out. As shown in FIG. 2B, each of rollers  59  for regulating the respective tracks of the belt conveyors  16  and  44  is in the form of a simple cylinder. 
     As mentioned before, the pivotal portion between the second and third boom components  41  and  42  and the individual belt conveyors are constructed in the same manner as in the case of the relation between the first and second boom components  15  and  41 , so that a detailed description of the arrangement of those components is omitted. In FIG. 1B, numerals are only used roughly to indicate the location of components including an external-tooth turntable bearing  60  that constitutes the pivotal portion between the second and third boom components  41  and  42 , a hopper  65  that constitutes granule delivery means at the junction between the second and third boom components  41  and  42 , a motor  61  (e.g., servomotor with position and speed detectors), of which the position and speed can be controlled, for rotating the third boom component  42  with respect to the second boom component  41 , a motor  62  for driving the belt conveyor  44  of the second boom component  41 , a belt conveyor  63  for use as granule transfer means of the third boom component  42 , a motor  64  as a drive source for the conveyor  63 , and a hopper  66  for dropping the granule from the distal end of the third boom component  42 . 
     The third boom component  42  is a boom component that is situated at the leading end and is preceded by no other boom component which is to rock. Accordingly, the third boom component  42  is not provided with any motor for rocking motion. 
     Further, a mast  69  is set up on the top surface of the distal end portion of the first boom component  15  on the stage side so as to be coaxial with the central axis of the external-tooth turntable bearing  45  that constitutes the pivotal portion between the first and second boom components  15  and  41 . First ends of suspension ropes  67  and  68 , such as wires or chains, are fastened to the mast  69 . The respective other ends of the suspension ropes  67  and  68  are fastened to the distal end portion and central portion of the second boom component  41 . Thus, in the relation between the first and second boom components  15  and  41 , the second boom component  41  is diagonally supported from above by means of the suspension ropes  67  and  68  so that its rigidity is maintained. At the same time, an excessive bending moment can be prevented from being generated in the rotating portion of the external-tooth turntable bearing  45 . 
     If the second boom component  41  is short or rigid enough, however, the suspension ropes  67  and  68  are not indispensable. 
     In the conventional apparatus, as mentioned before, the overall length of the boom body is changed by extending or contracting the next boom component, which is continuous with the stage-side boom component, with respect to this boom component. In the apparatus according to the present invention, however, the overall length of the boom body  4  is changed by turning the next or second boom component  41  with respect to the first boom component  15  on the stage side. Even if the second boom component  41  is turned with respect to the first boom component  15  in order to change the overall length of the boom body  4 , therefore, the distance from the distal end of the mast  69  to the distal end portion of the second boom component  41  and the distance from the distal end of the mast  69  to the central portion of the second boom component  41  cannot be changed. It is unnecessary, therefore, to adjust the lengths of the suspension ropes  67  and  68  in turning the second boom component  41  with respect to the first boom component  15 . 
     Accordingly, the suspension ropes  67  and  68  can be easily disposed without using any winch or the like for adjusting the lengths of the suspension ropes  67  and  68 , and the rigidity of the next or second boom component  41  and the strength of the external-tooth turntable bearing  45  that constitutes pivotal portion can be ensured. 
     In the present embodiment, the span of the third boom component  42  at the leading end is short, so that a mast need not be provided on the distal end of the second boom component  41  to support the third boom component  42 . In the case where the span of the third boom component  42  is long, however, the mast may be provided on the distal end of second boom component  41  with the same arrangement as aforesaid so that suspension ropes can be fastened to the mast to support the third boom component  42 . 
     In the present embodiment, moreover, the third boom component  42  at the leading end has a short span and small mass, so that it is suited for the case where the third boom component  42  is subjected to weaving for plane spreading such that it is continuously reversibly turned or rocked. 
     The following is a description of an outline of granule spreading operation by means of the granule transfer apparatus  1  according to the first embodiment. 
     First, adjustment of a distance r from the origin of a coordinate system based on the tower mast  2 , among position adjustments for the hopper  66  for spreading the granule, is achieved by adjusting the angle of turn of the second boom component  41  with respect to the first boom component  15  and the angle of turn of the third boom component  42  with respect to the second boom component  41 . 
     Let it be suppose that the substantial lengths of the first, second, and third boom components  15 ,  41  and  42  are L 1 , L 2  and L 3 , respectively, as shown in FIG.  1 B. If the second and third boom components  41  and  42  are turned for about ±180° with respect to the first boom component  15  in a manner such that the angle of turn of the third boom component  42  with respect to the second boom component  41  is kept at 0° where L 1 =60 m, L 2 =40 m, and L 3 =12 m are given (i.e., with the second and third boom components  41  and  42  arranged substantially in a straight line to obtain an overall length of L 2 +L 3 =52 m), as shown in FIG. 1A, the hopper  66  at the distal end portion of the third boom component  42  (in a granule spreading position) approaches the basal part of the tower mast  2 , so that the granule can be spread at the basal part of the tower mast  2 . 
     Thus, the straight distance r from the axis of the tower mast  2  to the hopper  66  can be freely adjusted within a range given by [L 1 −(L 2 +L 3 )]&lt;r≦[L 1 +L 2 +L 3 ] by regulating the angle of turn of the second boom component  41  with respect to the first boom component  15  and the angle of turn of the third boom component  42  to the second boom component  41 . 
     According to the present embodiment, therefore, the granule can be spread at the basal part of the tower mast  2  (r≈L 1 −(L 2 + 13 )) and spread in either a position (r≈L 1 +L 2 + 13 )) remote from the tower mast  2  or any intermediate position. Accordingly, it is unnecessary to use the tripper device for taking out the granule directly from the belt conveyor of the first boom component that is situated nearest to the stage and spreading it, which is essential to the conventional apparatus in which the overall length of the boom body is adjusted by extending or contracting the next boom component continuous with the stage-side boom component, with respect to this boom component. 
     In the case where the distance from the tower mast  2  to a target position for spreading is relatively short, that is, if the straight distance r from the axis of the tower mast  2  to the hopper  66  is shorter than the aforesaid [L 1 +L 2 +L 3 ], the position of the hopper  66  can be determined in accordance with the combination of (1) a turn angle θ of the stage  3 , (2) an angle θ′ between the first and second boom components  15  and  41 , and (3) an angle θ″ between the second and third boom components  41  and  42 . 
     The angles θ, θ′ and θ″ for the determination of the distance r may be combined in many ways. If the attitudes of the first, second, and third boom components  15 ,  41  and  42  based on a specific combination of the angles θ, θ′ and θ″ result in interference with an obstacle, therefore, another combination of the angles θ, θ′ and θ″ can be selected such that the interference with the obstacle can be avoided. Thus, the granule can be dropped into the target position r. 
     While the boom body  4  according to the first embodiment is composed of three boom components, the rigidity of the boom components and the pivotal portions can be ensured by means of the simple construction that is formed of the suspension ropes and the mast to which the ropes are anchored. If necessary, therefore, the boom body  4  can be composed of four boom components. 
     In order to enable the granule to be spread in a desired position through the distal end of the boom body  4  (i.e., from the hopper at the distal end of the leading boom component), however, the boom body may only be provided with at least two pivotal portions for turning the boom components so that it enjoys the degree of freedom of 2. 
     Thus, according to the first embodiment shown in FIGS. 1A and 1B, the granule can be dropped in the desired target position if the boom body  4  is composed of only the first and second boom components  15  and  41  without the use of the third boom component  42  so that the granule is bound to be discharged through the distal end portion of the second boom component  41 . In this case, the distal end of the boom body  4  (hence the distal end of the second boom component  41 ) can be situated in any desired position within a plane region in which the boom body  4  is movable by controlling the turn angle θ of the stage  3  that supports the boom body  4  and the angle θ′ between the first and second boom components  15  and  41 . 
     (Granule transfer apparatus according to second embodiment) 
     The following is a description of a second embodiment of the present invention, which is composed of a boom body having the degree of freedom of 2 and in which a boom body supporting portion is attached to a vehicle. 
     FIG. 8 is a side view showing the second embodiment, and FIG. 9 is a plan view. In this second embodiment, a caterpillar tractor  71  having a caterpillar on each side is provided with a boom body supporting portion  72 . A stage  73  is rotatably provided on the boom body supporting portion  72  in the same manner as in the first embodiment. The stage  73  is turned with respect to the boom body supporting portion  72  by means of a servomotor  74 . Mounted on the rotating shaft of the servomotor  74  is a detector (not shown), such as a pulse coder, for detecting the rotational speed and rotational position of the motor  74 . Since a turning mechanism for the stage  73  is constructed in the same manner as the one according to the first embodiment, a detailed description of its construction is omitted. 
     A pair of boom body mounting members  75  are fixed on the stage  73 , and a shaft is stretched between the pair of boom body mounting members  75  so as to extend parallel to the top surface of the stage  73 . The basal part of a first boom component  83  of a boom body  76  is rotatably mounted on the shaft. 
     As shown in FIG. 8, the distal end portion of the first boom component  76  is bent at an angle of about 20° to the other portion. One end of a pendant rope  77  is attached to the distal end portion of the first boom component  83 , while a movable pulley is mounted on the other end of the pendant rope  77 . An undulating rope  78  is stretched between the movable pulley and a fixed pulley mounted on a frame  79  that is set up on the stage  73 . The undulating rope  78  is wound up or off by means of a boom undulating winch  80 , whereby the tilt angle of the first boom component  83  can be adjusted. 
     A counterweight  82  is fixed on that side of the stage  73  which is remoter from the boom body  76 , and a controller  100  for controlling the granule transfer apparatus is placed on the stage  73 . 
     As in the first embodiment, the first boom component  83  is provided with a belt conveyor  85  that extends substantially covering the overall length of the first boom component  83 . A hopper  84  for delivering the granule to the belt conveyor  85  is located near a pivotal portion between the first boom component  83  and the stage. A motor  86  for driving the belt conveyor  85  is provided on the distal end portion of the first boom component  83 , and a hopper as granule delivery means for delivering the granule to a belt conveyor of a second boom component  90  is provided on the leading end portion. 
     Further, a pivotal portion, similar to the one according to the first embodiment shown in FIG. 2, and a turning mechanism  89  for turning the second boom component are arranged between the first and second boom components  83  and  90 . Numeral  88  denotes a servomotor for driving the turning mechanism  89 . A detector (not shown), such as a pulse coder, for detecting the rotational speed and rotational position is mounted on the motor shaft of the servomotor  88 . Since the turning mechanism  89  and the like are substantially the same as the examples shown in FIG. 2, a detailed description of those elements is omitted. 
     The second boom component  90  is provided with a belt conveyor  91 , which transports the granule delivered from the belt conveyor  85  of the first boom component  83  toward the distal end of the boom component  90 . The belt conveyor  91  is driven by a motor  92  that is mounted on the distal end portion of the second boom component  90 . Mounted on the distal end of the second boom component  90 , moreover, is a hopper  93  that throws out the granule, transported thereto by means of belt conveyor  91 , onto the ground. 
     According to the second embodiment, the boom component  76  is mounted on the caterpillar tractor  71 , so that the caterpillar tractor  71  can be moved to be situated in a required position. If the place where the caterpillar tractor  71  is located is inclined, in this case, the boom undulating winch  80  is actuated to adjust the tilt angle of the first boom component  83  so that the distal end of the second boom component  90  can move on the same horizontal plane. 
     Since the distal end portion of the first boom component  83  is bent, moreover, the angle of turn of the second boom component  90  is about ±150°, as shown in FIG.  9 . The angle of turn of the first boom component, i.e., the angle of turn of the stage, can be adjusted to ±180° or more. According to this second embodiment, the angle is adjusted to ±185°. 
     If the boom body supporting portion  72  is made as tall as a tower mast, as in the case of the first embodiment, the distal end portion of the first boom component  83  need not be bent in the manner shown in FIG.  8 . If the boom body supporting portion  72  is made taller, however, its stability worsens. In order to lower the center of gravity, according to the second embodiment, therefore, the boom body supporting portion  72  is limited in height, the first boom component  83  is inclined with its distal end portion bent, and the second boom component  90  is supported on the distal end of the bent portion to secure the height of a granule discharge section at the distal end of the boom body  76 , as shown in FIG.  8 . 
     Although the caterpillar tractor  71  having caterpillars is used as a traveling body according to the second embodiment, it may be replaced with a wheeled vehicle. In this case, the vehicle used may be one that is provided with an out-trigger for securing the stability of operation. Further, the traveling body may be a self-propelled vehicle having an engine or the like or a traction vehicle without an engine. If the traveling body is intended for reclamation, then it will be a vessel. 
     (Controller used in granule transfer apparatus according to first and second embodiments) 
     The following is a description of the controller  100  used for the operation of the granule transfer apparatuses according to the first and second embodiments. In the first embodiment, however, there are three boom components that constitute the boom with the degree of freedom of 3, so that three servomotors are used to turn each boom. However, the controller  100  shown in FIG. 10 is applicable to the case where the third boom component  42  is removed so that the boom has the degree of freedom of 2. 
     In the description to follow, the turning mechanism for turning the stage  3  or  73  (first boom component  15  or  83 ) is referred to as a first axis, and the servomotor  37  or  74  for driving the first axis as a first servomotor M 1 , for ease of explanation. Further, the turning mechanism for turning the second boom component  41  or  90  is referred to as a second axis, and the servomotor  53  or  88  for driving the second axis as a second servomotor M 2 . 
     The controller  100  includes a processor  101  for generally controlling the granule transfer apparatus. The processor  101  is bus-connected with a ROM  102 , RAM  103 , interfaces  104 ,  108 ,  109  and  110 , communication interface  105 , and servo circuits  106  and  107 . 
     The ROM  102  is loaded with system programs for the processor  101 , and the RAM  103  is utilized for temporary storage of data during the execution of processing. Further, the RAM  103  is provided partially with a nonvolatile memory, and operation pattern programs for automatic operation (mentioned later) are set and stored in the nonvolatile memory. The interface  104  is connected to various actuators and sensors of the granule transfer apparatus, and receives operation commands for the various actuators and signals from the sensors. In the case where the controller  100  is used in the granule transfer apparatus of the first embodiment, the interface  104  is connected to the motors  56  and  62  for driving the belt conveyor, motors for driving the transportation buckets, a drive source for the hydraulic cylinders  20  for finely adjusting the height of the stage  3 , etc. In the case where the controller  100  is used in the granule transfer apparatus of the second embodiment, moreover, the interface  104  is connected to the motors  86  and  92  for driving the belt conveyor, boom undulating winch  80 , etc. 
     The communication interface  105  is connected to a personal computer  116  for monitoring various set values and the present position of the distal end of the boom body  3  or  76 . In the first embodiment, the controller  100  is situated on the stage  3  over the tower mast  2 , and the personal computer  116  is located on the ground. Accordingly, the personal computer  116  and the communication interface  105  are connected by means of a cable, and the personal computer  116  and the communication interface  105  are provided with a serial/parallel converter for converting parallel signals into serial signals and converting serial signals into parallel signals, whereby serial communication is carried out. 
     The servo circuits  106  and  107  are digital servo circuits that are composed of a digital signal processor (DSP), ROM, RAM, etc., and carry out position loop control, speed loop control, and current loop control. More specifically, the servo circuit  106  drivingly controls the first servomotor M 1  ( 37  or  74 ) that drives the first axis (or drives the stage  3  or  73 ). It obtains a position deviation in accordance with a move command delivered from the processor  101  and a position feedback signal from a detector  114  such as a pulse coder, obtains a speed command by multiplying the position deviation by a position loop gain, obtains a speed deviation in accordance with the speed command and a speed feedback signal fed back from the detector  114 , and effects proportional-plus-integral control or the like in accordance with the speed deviation, thereby obtaining a torque command. Further, the servo circuit  106  detects the torque command and the driving current of the first servomotor M 1  to effect current loop control processing, obtains current commands for individual phases, and drives a servo amplifier  112 , which is composed of a transistor-inverter or the like, thereby drivingly controlling the first servomotor M 1  ( 37  or  74 ). 
     Moreover, a feedback signal for the position of the first servomotor M 1 , detected by the detector  114 , is applied to the interface  108 . Based on a feedback signal for this position, the processor  101  can obtain the rotational position of the servomotor M 1 , thereby detecting the turn position of the stage  3  or  73  (first boom component  15  or  83 ). 
     The servo circuit  107  is a circuit that controls a serve amplifier  113  to drive the second servomotor M 2  ( 53  or  88 ) for driving the second axis (mechanism for turning the second boom component  41  or  90 ). The interface  109  is an interface that receives a position feedback from a detector  115  for detecting the rotational position and speed of the second servomotor M 2 . Since these elements  107 ,  113 ,  115  and  109  operate substantially in the same manner as the elements  106 ,  117 ,  114  and  108  for drivingly controlling the first servomotor M 1 , a description of their operations is omitted. 
     The processor  101  can detect the rotational position of the stage  3  or  73  or the first boom component  15  or  83  and the rotational position of the second boom component  41  or  90  in accordance with position feedback signals for the first and second servomotors M 1  and M 2  delivered from the detector  114  or  115  to the interface  108  or  109 . Therefore, the processor  101  can obtain the distal end position of the boom body  3  or  76  or granule release position, in an XY orthogonal coordinate system set by coordinate transformation, from the rotational positions, and transmit the obtained value to the personal computer  116  and a control panel  117  (mentioned later) and display it. 
     In the case where the first embodiment is provided with the third boom component  42 , which is driven by means of a servomotor, another set of elements including the aforesaid servo circuit, amplifier, inverter, detector must be added. 
     The interface  110  is connected to the control panel  117  by means of a cable. The interface  110  and the control panel  117  are provided with a converter for converting parallel signals into serial signals and converting serial signals into parallel signals, whereby serial communication is carried out between the interface  110  and the control panel  117 . If the controller  100  is situated on the stage  3  over the tower mast  1  so that operation is performed on the ground, as in the case of the first embodiment, the communication path may be replaced with a cable for radio operation. In this case, the interface  110  and the control panel  117  have to be provided with a transmitter and a receiver. 
     The control panel  117  is provided with a display  118  composed of a CRT or liquid crystal, which displays various set values, present position (position of the boom body end in the set XY orthogonal coordinate system and rotational angle of each boom component), operation mode, set boom body end movement region (set granule spreading region), etc. 
     In FIG. 10, symbol L 1  designates a first boom manual lever for turning the stage  3  or  73  or the first boom component  15  or  83  in accordance with a manual command. L 2  designates a second boom manual lever for turning the second boom component  41  or  90 . The first and second boom manual levers L 1  and L 2  are constructed so that they can be moved to the left or right from a center position. If the first boom manual lever L 1  is moved to the right, a command is generated to turn the first boom component  15  or  83  in the clockwise direction (+direction) of FIG. 1A or  9  around the boom body supporting portion  2  or  72 . If the lever L 1  is moved to the left, on the other hand, a command is generated to turn the first boom component in the counterclockwise direction (−direction). Three different speeds can be ordered for either direction, and the individual speeds are separately set in advance. The second boom manual lever L 2  is operated in like manner. Thus, commands are generated to turn the second boom component  41  or  90  in the clock and counterclockwise directions at speeds ordered by the lever L 2 . 
     Further, operating levers Lx and Ly are semiautomatic operating levers that are used to move the boom body end straight and parallel to the X- or Y-axis in the set XY orthogonal coordinate system. The origin for the angles of turn of the first and second boom components are located on an intermediate point in turnable range, and the first boom component  15  or  83  can rotate for angles of ±185° around the origin. On the other hand, the second boom component  41  or  90  can rotate for about ±150° around the origin. 
     When the first and second boom components are positioned individually on the origin, the axis of the first boom component  15  or  83  and the axis of the second boom component  41  or  90  are aligned with each other, as shown in FIGS. 1A and 9. This axis position is regarded as a Y-axis position in the XY orthogonal coordinate system, and the X-axis is set in the direction perpendicular to the Y-axis. Thus, in this XY orthogonal coordinate, system, the center of rotation of the first boom component  15  or  83  (stage  3  or  73 ) is regarded as the origin, the axial direction of the boom body with the rotational positions of the first and second boom components at 0° is received as the Y-axis direction, and the direction perpendicular to the Y-axis is regarded as the X-axis direction. In FIGS. 1A and 9, the direction in which the boom body end is situated is set as the positive Y-axis direction, and the rightward direction perpendicular to the Y-axis direction is set as the positive X-axis direction. 
     If the X-axis direction semiautomatic lever Lx is moved to the right (or in the +direction) in FIG. 10 with respect to the orthogonal coordinate system set in this manner, a move command is generated to move the boom body end parallel to the X-axis in the positive direction. If the lever Lx is moved to the left (or in the −direction), on the other hand, a move command is generated to move the boom body end parallel to the X-axis in the negative direction. If the Y-axis direction semiautomatic lever Ly is moved upward (or in the +direction) in FIG. 10, a command is generated to move the boom body end parallel to the Y-axis in the positive direction. If the lever Lx is moved downward (or in the −direction), on the other hand, a command is generated to move the boom body end parallel to the Y-axis in the negative direction. 
     Numerals  120 ,  121  and  122  denote mode switches. The first and second boom manual levers L 1  and L 2  are allowed to be operated only when the manual mode switch  120  is turned on. When the semiautomatic mode switch  121  is turned on, the boom body end is allowed to move straight as the semiautomatic levers Lx and Ly are operated. When the automatic mode switch  122  is turned on, moreover, operation based on set programs (pattern operation) can be started. 
     Numeral  119  denotes numeric keys for setting various commands and data, which include key switches for delivering power-on and -off commands and commands to the boom undulating winch  80 , motors  53 ,  64 ,  86  and  92  for driving the belt conveyor, and various actuators. 
     Numerals  123  and  124  denote switches for setting regions for granule spreading, such as fresh concrete placing (mentioned later), and numeral  125  denotes a key switch for ordering the pitch direction of pattern operation for automatic operation, which will be described later. 
     (Operation of granule transfer apparatus) 
     Referring now to the flowchart of FIG. 11, there will be described the operation of the granule transfer apparatus according to the first or second embodiment having the degree of freedom of 2, carried out in a manual mode by the processor  101  of the controller  100 . 
     When the manual mode switch  120  is turned on, the processor  101  determines whether or not any of the manual levers L 1  and L 2  have been operated (Steps a 1  and a 2 ). If not determined that any of the manual levers have been operated, no movement commands are delivered to the servo circuits  106  and  107 , and a stop state is maintained (Step a 13 ). 
     If the first boom manual lever L 1  is operated, then whether the lever is moved in the positive or negative direction is determined, and the stage of the operating position, in terms of the first, second or third, is detected (Steps a 2 , a 3  and a 5 ). If the operating direction of the lever L 1  is positive, a move command to rotate the first boom component (stage) in the positive direction (clockwise direction) at a set speed corresponding to the operation stage number is delivered to the servo circuit  106  (Step a 4 ). The processor  101  gives move commands to the servo circuits  106  and  107  with every predetermined distribution period. In this case, movements for the distribution period, corresponding to the ordered direction (positive direction), are delivered to the servo circuit  106 . 
     If the operating direction of the lever L 1  is negative, a move command is outputted to rotate the first boom component (stage) in the negative direction (counterclockwise direction) at the set speed corresponding to the operation stage number (Step a 6 ). In consequence, the first boom component (stage) turns in the set speed in the ordered direction at the command speed. 
     If the second boom manual lever L 2  is operated (Step a 7 ), the operating direction and the operation stage are read (Steps a 8 , a 9  and a 11 ), and a move command for movement in the operating direction at the set speed corresponding to the operation stage number is delivered to the servo circuit  107  (Steps a 10  and a 12 ). Thereupon, the second boom component turns in the ordered direction at the command speed. 
     When the manual levers L 1  and L 2  are returned to their respective neutral positions, the delivery of the move command is stopped (Step a 13 ), and the boom components cease to turn. 
     The operations by means of the manual levers L 1  and L 2  include individually turning the boom components in response to manual commands, and are applied to the case where the boom components are individually turned to spread the granule or programs are taught in automatic operation. In the first and second embodiments, in particular, the operations are used in setting the boom body end movement region (granule spreading region). 
     Referring now to the flowchart of FIG. 12, there will be described processing the processor  101  executes when the semiautomatic mode switch  121  is turned on to establish a semiautomatic mode. 
     Before the execution of operation in the semiautomatic mode, the moving speed of the boom body end and an override value are first set in advance by means of the key switches  119 . The moving speed is set to be one used in normal automatic operation. The override value determines the actual speed of the boom body end position and is set as a percentage of the set speed. The percentage of the set speed is used as the moving speed. If the override value is set at 60%, for example, the moving speed command for the boom body end position is 60% of the set speed command. By changing this override value, therefore, the speed command to be used actually can be adjusted to any desired value without changing the set speed. 
     When the semiautomatic mode is selected, the processor  101  reads the set speed and the override value (Step b 1 ), determines whether or not the semiautomatic levers Lx and Ly for the X- and Y-axis directions are operated (Steps b 2  and b 8 ). If neither of the levers Lx and Ly are operated, the boom is kept in the stop state without the distribution of the move commands (Step b 14 ). 
     If it is concluded that the X-direction semiautomatic lever Lx is operated while the processes of Steps b 1 , b 3 , b 8  and b 14  are being repeatedly executed (Step b 2 ), the operating direction of the lever Lx is read (Step b 3 ). If the operating direction is positive, the move command speed is obtained in accordance with the set speed and the override value read in Step b 1 , and the movement within the distribution period time for the move command corresponding to the move command speed is obtained and settled as the move command for the positive X-axis direction. Further, the respective rotational angles of the individual axes (individual boom components) corresponding to the movement in the aforesaid distribution period are obtained by a transformation matrix for transformation from the orthogonal coordinate system into the respective rotational angles of the individual axes (angles of turn of the first and second boom components), and movements corresponding to the individual rotational angles are delivered to the servo circuits  106  and  107  (Steps b 4  and b 5 ). 
     Thereupon, the servo circuits  106  and  107  carry out feedback control for the position, speed, and current, thereby driving the servomotors M 1  and M 2  to move the boom body end in the positive direction parallel to the X-axis, as mentioned before. 
     If it is concluded in Step b 3  that the operating direction of the semiautomatic lever Lx is the negative, move commands are delivered to the servo circuits  106  and  107  so that the boom body end moves in the negative direction to the X-axis in the same manner as aforesaid (Steps b 6  and b 7 ). 
     If it is concluded that the Y-direction semiautomatic lever Ly is operated (Step b 8 ), on the other hand, the direction of the move command is read from the operating direction of the lever Ly (Step b 9 ), the movements in the command direction for the distribution period based on the moving speed command obtained according to the set speed and the override value is obtained, the movements are converted into the angles of turn of the individual axes, and the movements corresponding to these angles of turn are delivered to the servo circuits  106  and  107 , whereupon the boom body end is moved straight and parallel to the Y-axis in the commanded direction (Steps b 10 , b 11 , b 12  and b 13 ). 
     In the semiautomatic mode, as described above, the boom body end can be moved parallel to the X- or Y-axis in the XY orthogonal cooperate system in the positive or negative direction by operating the semiautomatic lever Lx or Ly. Thus, the semiautomatic operation can be utilized in rectilinearly spreading the granule parallel to the X- or Y-axis or in moving the boom body end to an instruction position to set the boom body end movement region (granule spreading region) in an automatic mode, which will be described later. 
     Referring now to flowcharts of FIGS. 13 to  15 , there will be described processing the processor  101  executes in the automatic operation mode. 
     In the first and second embodiments, the automatic operation is carried out in accordance with set patterns. The set patterns will be described first. 
     The granule spreading operation, such as fresh concrete placing, consists mainly of spreading on flat surfaces. As shown in FIG. 16, therefore, eight patterns are first supposed to be able to be set for the spreading region (boom body end movement region) and the path of movement of the boom body end in the spreading region. First, eight patterns A to H are set and stored in the following manner, depending on (1) the direction, in terms of the X- or Y-axis direction, in which the boom body end reciprocates, (2) the movement pitch direction, in terms of positive or negative direction, for the reversal of course with respect to the axis perpendicular to the moving direction, and (3) the direction for the first movement at the start of the automatic operation. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                 DIRECTION OF 
                 DIRECTION AT 
                 PITCH 
               
               
                 PATTERN 
                 RECIPROCATION 
                 MOVE START 
                 DIRECTION 
               
               
                   
               
             
            
               
                 A: 
                 X-axis 
                 X+ 
                 Y+ 
               
               
                 B: 
                 X-axis 
                 X+ 
                 Y− 
               
               
                 C: 
                 X-axis 
                 X− 
                 Y+ 
               
               
                 D: 
                 X-axis 
                 X− 
                 Y− 
               
               
                 E: 
                 Y-axis 
                 Y+ 
                 X+ 
               
               
                 F: 
                 Y-axis 
                 Y+ 
                 X− 
               
               
                 G: 
                 Y-axis 
                 Y− 
                 X+ 
               
               
                 H  
                 Y-axis 
                 Y− 
                 X− 
               
               
                   
               
            
           
         
       
     
     In the embodiment shown in FIG. 13, the direction of reciprocation is settled by previously setting a flag D. In the case where the flag D is set at “0”, the moving direction is adjusted to the X-axis direction. If the flag is set at “1”, the moving direction is adjusted to the Y-axis direction. The moving direction at the start of the automatic operation is ordered according to the operating direction of the X- or Y-axis semiautomatic lever Lx or Ly. The pitch direction is selected by means of the reversible switch  125 . 
     Further, the moving direction for rectilinear movement is set in accordance with the set speed and the override value (moving speed =set speed×override value). Furthermore, a pitch value and a spreading region  130  (see FIG. 16) are set. The setup of the spreading region (boom body end movement region)  130  is effected by moving the boom body end by the aforementioned manual, or semiautomatic operation and giving instructions for two points on a diagonal line of the target spreading region. Thus, XY coordinate positions (respective rotational angles of the first and second boom components) are taught and stored by depressing the spreading start position instruction switch  123  after positioning the boom body end in a spreading start position. 
     Then, the XY coordinate positions (respective rotational angles of the first and second boom components) are taught and stored by positioning the boom body end in a position diagonal to the spreading start position in the rectangular target spreading region and depressing the spreading end key switch  124 . If the XY coordinate position for the taught spreading start position and a spreading end position are (Xs, Ys) and (Xe, Ye), respectively, the spreading region  130  is set as a rectangular region having an X-axis value between Xs and Xe and a Y-axis value between Ys and Ye. 
     The processor  101  of the controller  100  starts the processing of FIG. 13 if the automatic mode switch  122  is turned on after the spreading region  130 , set speed override value, pitch value, direction of reciprocation (flag D indicative of the X- or Y-direction), and reversible switch  125  for settling the pitch direction are set in the manner described above and the boom body end position is situated in the spreading region  130  manually or semiautomatically (normally, situated at the spreading start position). 
     First, the set speed and the override value are read (Step c 1 ), and whether or not the flag D for storing the set direction of reciprocation is “0” is determined (Step c 2 ). If the flag D is “0”, whether or not the X-direction semiautomatic lever Lx (this lever Lx serves as a lever for adjusting the moving direction at the start of the automatic operation to the X-axis direction) is operated is then determined (Step c 3 ). If the flag D is “1”, on the other hand, whether or not the Y-direction semiautomatic lever Ly (this lever Ly serves as a lever for adjusting the moving direction at the start of the automatic operation to the Y-axis direction) is operated is determined (Step c 11 ). If neither of the levers Lx and Ly is operated, the delivery of the move command is stopped so that the movement of the boom components is stopped (Step c 19 ). 
     The motors for driving the belt conveyor and bucket are then actuated, it is ascertained that dropping of the granule from the boom body end is started, and the direction of reciprocation is adjusted to the X-axis direction (flag D=0). If an operator moves the X-direction semiautomatic lever Lx in, for example, the positive direction in this case (Step c 4 ), the processor  101  concludes that “the moving direction for the start of the automatic operation is the positive X-direction” (If the semiautomatic lever for the direction different from the set direction of reciprocation is operated, it is ignored. If the Y-direction semiautomatic lever Ly is operated with the flag D=0, for example, it is ignored.) Further, reversal setting by means of the reversible switch  125  (switch for settling the pitch direction, positive or negative) is determined (Step c 5 ). If the lever Lx is operated in the positive (+) direction, and if the reversible switch is set in the positive (+) direction, then the processor  101  starts processing the pattern A. 
     Referring now to the flowchart of FIG. 14A, there will be described the processing of the pattern A executed by the processor  101 . 
     First, the movements for the distribution period corresponding to the moving speed that is settled depending on the set speed and the override value are obtained, these movements are added to the present X coordinate position of the boom body end, and the XY coordinate position of the boom body end moving in the present distribution period, on the orthogonal cooperate system, is obtained (Step d 1 ). Then, whether or not this position is a pitch position is determined. At this point of time, the decision implies a move command in the positive X-axis direction, so that the pitch position takes a maximum value on the X-axis of the spreading region  130 . Accordingly, it is determined by whether or not this maximum X-axis value is reached by a position ordered in the present distribution period (Step d 2 ). 
     If this pitch position is not reached, the respective rotational angles of the individual axes corresponding to the XY coordinate position for the boom body end moving in the present distribution period are obtained by the transformation matrix for transformation from the XY coordinate system into the rotational angles, movements corresponding to the rotational angles are delivered to the rotation servo circuits  105  and  107 , and the XY coordinate value is updated (Step d 3 ), whereupon the program returns to Step d 1 . As mentioned before, the servo circuits  105  and  107  carry out feedback control operations for the position, speed, and current, thereby driving the servomotors M 1  and M 2  to move the boom body end in the positive direction parallel to the X-axis. 
     Thereafter, the processes of Steps d 1  to d 3  are executed repeatedly, whereby the boom body end is moved in the positive X-axis direction at a moving speed based on the set speed and the override value. If it is concluded that a maximum X-coordinate value of the spreading region  130  is reached or exceeded by the X-axis coordinate value of the boom body end position to be moved with every distribution period (Step d 2 ), whether or not the spreading end position is reached is determined (Step d 4 ). Since the pitch direction for the pattern A is the positive Y-axis direction, this decision depends on whether or not a maximum Y-coordinate value of the spreading region  130  is exceeded by a value obtained by adding the pitch value to the Y-axis coordinate value of the present position. If the maximum value is exceeded, it implies that spreading into the spreading region  130  is finished, so that the automatic operation terminates. If the maximum value is not exceeded, on the other hand, pitch operation is carried out. Thus, movements for the distribution period during which the boom body end moves in the positive Y-axis direction at the moving speed are obtained and added to the Y-axis coordinate value of the present position, so that a target position is obtained, then the respective rotational angles of the individual axes are obtained from this position, and movements of the servomotors M 1  and M 2  for the rotational angles are obtained and outputted (Step d 5 ). A move command for moving by a set pitch value is outputted, and whether or not the boom body end is moved by the pitch value is determined (Step d 6 ). If this is not done, the processes of Steps d 5  and d 6  are executed repeatedly. 
     When the boom body end is thus moved for the set pitch value, the coordinate position in the orthogonal cooperate system of the boom body end moving in the distribution period for the movement in the negative direction at the aforesaid moving speed is obtained (Step d 7 ), and whether or not this position is the pitch position is determined (Step d 8 ). Since this decision implies a movement in the negative X-axis direction, it depends on the determination as to whether or not a minimum X-axis coordinate position of the spreading region  130  is exceeded by the X-axis coordinate position of the position to be moved. The pitch position is not reached yet if the minimum X-axis coordinate position of the spreading region  130  is exceeded by the X-axis coordinate position of the position to be moved. Therefore, the respective rotational angles of the individual axes corresponding to the XY coordinate position for the boom body end moving in the present distribution period are obtained by the transformation matrix for transformation from the XY coordinate system into the rotational angles, movements corresponding to the rotational angles are delivered to the rotation servo circuits  105  and  107 , and the XY coordinate value is updated (Step d 9 ), whereupon the program returns to Step d 7 . Thereafter, the processes of Steps d 7  to d 9  are executed repeatedly. 
     If it is concluded in Step d 8  that the minimum X-axis coordinate position of the spreading region  130  is not exceeded by the X-axis coordinate position to be moved and that a pitch switching position is reached, the program proceeds to Step d 10 , whereupon whether or not the spreading end position is reached is determined. This decision is the same process as the one in Step d 4 . The set pitch value is added to the present Y-axis coordinate value, and whether or not the maximum Y-axis coordinate value of the spreading region  130  is exceeded by the resulting value is determined. If the maximum value is exceeded, the automatic spreading operation is finished. If the maximum value is not exceeded, on the other hand, a move command for moving by the set pitch value in the positive Y-axis direction as in Steps d 5  and d 6  is outputted (Steps d 11  and d 12 ). When this pitch operation is completed, the program returns to Step d 1 , whereupon the aforementioned process of Step d 1  and the subsequent processes are executed. 
     Returning to FIG. 13, processing of the pattern B is started if it is concluded in the process of Step c 5  that the reversible switch  125  is set at “reverse (−)”. More specifically, the processing of the pattern B is started when the flag D is set at “0” so that the direction of reciprocation is the X-axis direction and if the positive X-axis direction and the negative Y-axis direction are ordered as the first moving direction and the pitch direction, respectively. 
     FIG. 14B is a flowchart for the processing of the pattern B executed by the processor  101  of the controller  100 . The pattern B differs from the aforesaid pattern A only in that the pitch direction is reverse (negative Y-axis direction). Thus, the flowcharts are different in the following points. While the pitch direction for Steps d 5  and d 11  for the pattern A is the positive Y-axis direction, that for Steps e 5  and e 11  is the negative Y-axis direction. In Steps e 4  and e 10 , moreover, the spreading end position is detected depending on whether or not a value obtained by subtracting the set pitch value from the present Y-axis coordinate position is not greater than a minimum Y-axis value of the spreading region  130  is determined, and the automatic spreading operation is finished if the obtained value is not greater. Since the other processes are executed in the same manner, a detailed description of those processes is omitted. 
     Further, the processor  101  starts processing the pattern C if flag D=0 is given so that the X-direction semiautomatic lever Lx is operated in the negative direction with the reversible switch  125  set at “forward (+)” (Steps c 2 , c 3 , c 4  and c 8 ), as shown in FIG.  13 . 
     The processing of the pattern C (not shown) differs from the processing of the pattern A in that the direction for the start of the first movement for the pattern C is the negative X-axis direction, while that for the pattern A is the positive X-axis direction. Thus, the processing of the pattern C differs from the processing of the pattern A only in the following points. In FIG. 14A, the “positive X-axis direction” is replaced with the “negative X-axis direction” in the process of Step d 1 , and the “negative X-axis direction” is replaced with the “positive X-axis direction” in the process of Step d 7 . While the detection of the pitch position in Step d 2  depends on whether or not the minimum X-axis coordinate position of the spreading region  130  is not exceeded by the X-axis coordinate position to be moved, the detection of the pitch position in Step d 8  depends on whether or not the value of the X-axis coordinate position to be moved is not smaller than the maximum value of the X-axis coordinate position of the spreading region  130 . 
     If it is concluded in Step c 8  of FIG. 13 that the reversible switch  125  is set at “reverse (−)”, the processor  101  carries out processing of the pattern D. The processing of the pattern D (not shown) differs from the processing of the pattern B shown in FIG. 14B in that the direction for the start of the first movement for the pattern D is the negative X-axis direction, while that for the pattern B is the positive X-axis direction. Thus, the processing of the pattern D differs from the processing of the pattern B only in the following points. In FIG. 14B, the “positive X-axis direction” is replaced with the “negative X-axis direction” in the process of Step e 1 , and the “negative X-axis direction” is replaced with the “positive X-axis direction” in the process of Step e 7 . While the detection of the pitch position in Step e 2  depends on whether or not the minimum X-axis coordinate position of the spreading region  130  is not exceeded by the X-axis coordinate position to be moved, the detection of the pitch position in Step e 8  depends on whether or not the value of the X-axis coordinate position to be moved is not smaller than the maximum value of the X-axis coordinate position of the spreading region  130 . 
     Returning to FIG. 13, processing of the pattern E is started (Step c 14 ) when the flag D is set at “1” (Step c 2 ), the Y-axis semiautomatic lever Ly is operated (Step c 11 ), its operating direction is positive direction (Step c 12 ), and the reversible switch  125  is set at “forward (+)” (Step c 13 ). FIG. 15A is a flowchart showing the processing of the pattern E. The pattern E and the pattern A are different in the reciprocal relation between the X- and Y-axes. For the pattern E, the direction of reciprocation is the Y-axis direction, and the pitch direction is the positive X-axis direction. Thus, the detection of the pitch position in Step f 2  depends on whether or not the value of the Y-axis coordinate position to be moved is not smaller than the maximum Y-axis value of the spreading region  130 , while the detection in Step f 8  depends on whether or not the value of the Y-axis coordinate position to be moved is not greater than the minimum Y-axis value of the spreading region  130 . Further, it is concluded in Steps f 4  and f 10  that the automatic spreading is finished if the maximum X-axis value of the spreading region  130  is exceeded by a value obtained by adding the pitch value to the present X-axis coordinate position. Since the processing of the pattern E differs from the processing of the pattern A only in the points described above, it is only illustrated in the flowchart of FIG. 15A, and a detailed description of the processing is omitted. 
     If it is concluded that the reversible switch  125  is set at “reverse (−)” in Step c 13  of FIG. 13, the processor  101  starts processing the pattern F (Step c 15 ). The processing of the pattern F is the processing shown in FIG.  15 B. As seen from the comparison between FIGS. 15A and 15B, the processing of the pattern F differs from the processing of the pattern E only in the following points. In the processes of Steps g 5  and g 11 , the pitch direction is the negative X-axis direction. Besides, the detection of the termination of automatic spreading in Steps g 4  and g 10  depends on whether or not a value obtained by subtracting the set pitch value from the present X-axis coordinate value is not greater than the minimum X-axis value of the spreading region  130 . 
     The processor  101  carries out processing of the pattern G (Step c 17 ) when the flag D is set at “1”, the Y-axis semiautomatic lever Ly is operated in the negative direction, and the reversible switch  125  is set at “forward (+)” (Steps c 3 , c 11 , c 12  and c 16 ). If the reversible switch  125  is set at “reverse (−)”, on the other hand, the processor  101  carries out processing of the pattern H. 
     Flowcharts for the processing of the patterns G and H are omitted. The pattern G differs from the pattern E in that the first direction of reciprocation is the negative Y-axis direction. The processing of the pattern G can be effected by only reversing the moving directions in Steps f 1  and f 7  in the processing of the pattern E shown in FIG.  15 A. In a step corresponding to Step f 2 , moreover, the detection of the pitch position depends on whether or not the value of the Y-axis coordinate position to be moved is not greater than the value of the minimum Y-axis coordinate position of the spreading region  130 . In a step corresponding to Step f 8 , the detection of the pitch position depends on whether or not the value of the Y-axis coordinate position to be moved is not smaller than the value of the maximum Y-axis coordinate position of the spreading region  130 . 
     Further, the processing of the pattern H differs from the processing of the pattern F shown in FIG. 15B in that the first moving direction is reversed to be the negative Y-axis direction. Thus, the processing of the pattern H can be effected by reversing the moving directions in Steps g 1  and g 7  in the processing of FIG.  15 B. In a step corresponding to Step g 2 , moreover, the detection of the pitch position depends on whether or not the value of the Y-axis coordinate position to be moved is not greater than the value of the minimum Y-axis coordinate position of the spreading region  130 . In a step corresponding to Step g 8 , the detection of the pitch position depends on whether or not the value of the Y-axis coordinate position to be moved is not smaller than the value of the maximum Y-axis coordinate position of the spreading region  130 . 
     According to the present embodiment, as described above, the automatic spreading operation can be executed by selecting any one operation pattern out of the eight patterns. In executing an automatic spreading operation, some spreading patterns for spreading granule in a rectangular plane region are set in advance and any one is selected from among these patterns. Then the granule such as fresh concrete is spread over the plane region with the selected pattern up to the predetermined height. 
     In the case where an optional path of movement (granule dropping position path) is provided for the boom body end in spreading the granule on a desired shape, however, this path is taught to the granule transfer apparatus so that the boom body end can be moved along the instruction path to drop the granule in playback operation. 
     In this case, the control panel  117  is provided with instruction buttons, and the boom body end is situated on the starting point of the path by the aforementioned manual or semiautomatic operation. The respective rotational positions of the boom components, that is, the respective rotational positions of the servomotors M 1  and M 2 , are taught and stored by depressing the instruction buttons. The boom body end is moved to the next position, and the respective rotational positions of the servomotors M 1  and M 2  for the reached position are taught in like manner by depressing the instruction buttons. A command for linear interpolation between the two points is inputted and stored. Thereafter, the subsequent points are successively taught and stored, and commands for linear interpolation between those points are taught. The boom body end can be moved along a circular arc between two points by teaching the starting and ending points of the circular arc and an intermediate point between them and teaching circular arc interpolation for the circular arc that passes through those three points. Thus, the points on the path are taught in succession, whether the line for the interpolation between the points is a straight line or a circular arc is ordered, and the path and operation programs are taught. 
     Then, the boom body end is moved along the instruction path at the set speed by giving a playback command, and the granule dropped from the boom body end is spread.