Patent Publication Number: US-2022219953-A1

Title: Controller, boom device, and crane vehicle

Description:
TECHNICAL FIELD 
     The present invention relates to a controller that controls a boom device including a boom and a winch, a boom device, and a crane vehicle mounted with the boom device. 
     BACKGROUND 
     A crane vehicle is generally mounted with a boom device (see Japanese Patent Laid-Open No. 7-172775). The boom device disclosed in Japanese Patent Laid-Open No. 7-172775 includes a telescopic boom, a boom drive unit, a winch having a wire drum around which a wire is wound, a winch drive unit, a load hook provided at a tip of the wire, and a hook fixing ring. The boom is supported by a swivel base such that the boom can be raised and lowered. The boom drive unit extends and retracts and raises and lowers the boom. The wire is pulled out from the wire drum and wound around a distal end of the boom, and the load hook is provided at an end of the wire. The winch drive unit drives the winch to wind the wire around the wire drum or to unwind the wire from the wire drum. The hook fixing ring is provided on the swivel base, and the load hook is hung on and fixed to the hook fixing ring during crane travelling (non-working time). 
     The boom device disclosed in Japanese Patent Laid-Open No. 7-172775 includes a control device that controls the boom drive unit and the winch drive unit in order to perform a safe boom storage operation at the end of work and a safe boom unfolding operation at the start of work. The control device controls the drive of the winch drive unit in the boom storage operation. Specifically, in the storage operation, an operator first retracts and raises the boom, and hangs the load hook on the hook fixing ring. Next, the operator operates a boom drive device to lower the boom. The control device winds up the wire while automatically controlling the winch drive unit according to the lowering of the boom so that the wire does not loosen. 
     The control device controls the drive of the winch based on a wire length S detected by a sensor for detecting a length of the wire and a derrick angle θ of the boom detected by a derrick angle sensor such that the wire length S and the derrick angle θ have an ideal correspondence D (the wire is not excessively loosened or stretched). The ideal correspondence D is obtained by experiments or simulation using an actual machine, and is stored in a storage unit in advance. 
     The ideal correspondence D varies depending on geometry constituted by a length of the boom in a retracted state, a position of the distal end around which the wire is wound, a derrick fulcrum position, a position of the hook fixing ring, and the like. In this case, the ideal correspondence D, which is unique to each type of boom devices, needs to be determined, and the control device needs to be designed for various boom devices. 
     Therefore, an object of the present invention is to provide a controller that can automatically store or raise a boom and can be commonly used for various boom devices. 
     SUMMARY OF THE DISCLOSURE 
     (1) A controller according to the present invention is used for a boom device including a base, a boom supported by the base and capable of being raised and lowered between a lowered position and a raised position, a winch having a wire wound around a wire drum and wound around a distal end of the boom, a load hook provided at a tip of the wire, a first drive source configured to raise and lower the boom, a second drive source configured to drive the winch and to unwind the wire from the wire drum or wind the wire around the wire drum, an engaging member provided on the base and to which the load hook suspended from the distal end of the boom at the raised position is engaged in a detachable manner, a derrick angle sensor configured to detect a derrick angle of the boom, and a length sensor configured to detect an unwinding length of the wire from the distal end of the boom. The controller according to the present invention includes a memory configured to store specified values corresponding to a length of the boom and a position of the engaging member with respect to a derrick fulcrum of the boom. The controller according to the present invention calculates a displacement distance from the distal end of the boom to the engaging member based on the derrick angle of the boom detected by the derrick angle sensor and the specified values read out from the memory, and executes an automatic boom drive process of driving the winch while raising or lowering the boom between the lowered position and the raised position in a state where the load hook is engaged with the engaging member such that the displacement distance is a distance corresponding to the length detected by the length sensor, or a wire speed which is an unwinding speed or a winding speed of the wire is calculated based on the calculated displacement distance, and the calculated wire seed is a speed corresponding to a detected wire speed calculated based on a detected value of the length sensor. 
     By executing the automatic boom drive process, the controller can automatically perform a boom raising operation or a boom storage operation. Therefore, work of the operator is facilitated in the boom raising operation or the boom storage operation. Further, the controller calculates the displacement distance from the distal end of the boom to the engaging member, and drives the winch while raising and lowering the boom such that the calculated displacement distance is the distance corresponding to the length detected by the length sensor, or the wire speed calculated based on the calculated displacement distance is the speed corresponding to the detected wire speed calculated based on the detected value of the length sensor. Therefore, the controller can prevent the wire from being loosened, and can also prevent breakage and the like in the boom device. Furthermore, since the controller calculates the displacement distance from the distal end of the boom to the engaging member based on the specified values stored in the memory corresponding to the length of the boom and the position of the engaging member with respect to the derrick fulcrum of the boom, the specified values read out from the memory change depending on a type of the boom device, and the controller can be commonly used with various boom devices. 
     (2) The first drive source may be a telescopic cylinder. The controller according to the present invention keeps an extension and retraction speed of the cylinder constant in the automatic boom drive process. 
     Since the controller raises and lowers the boom while keeping the extension and retraction speed of the cylinder constant, a target for controlling the drive according to the displacement distance may be limited to the second drive source. Accordingly, the controller can easily control the boom device. Further, since the cylinder is extended and retracted at a constant speed, a derrick speed of the boom visible to the operator does not fluctuate little by little, which gives the operator a sense of security. 
     (3) The controller according to the present invention may keep an angular velocity of the boom that is raised and lowered constant in the automatic boom drive process. 
     Since the controller raises and lowers the boom while keeping the raising and lowering angular velocity of the boom constant, the target for controlling the drive according to the displacement distance may be limited to the second drive source. Accordingly, the controller can easily control the boom device. Further, since the angular velocity of the boom is constant, the operator can be given a sense of security as compared with the case where the angular velocity of the boom fluctuates little by little according to the displacement distance. 
     (4) The controller according to the present invention may keep a rotation speed of the winch constant in the automatic boom drive process. 
     Since the controller keeps the rotation speed of the winch constant, the target for controlling the drive according to the displacement distance may be limited to the first drive source. Accordingly, the controller can easily control the boom device. 
     (5) The boom device may further include a tension sensor configured to detect tension applied to the wire. The memory stores in advance a threshold for determining an allowable range of a difference between the displacement distance and the unwinding length of the wire detected by the length sensor. In the automatic boom drive process, the controller drives the winch while raising and lowering the boom between the lowered position and the raised position such that the difference between the displacement distance and the length detected by the length sensor is equal to or less than the threshold. The controller corrects the threshold according to a magnitude of the tension detected by the tension sensor. 
     For example, when the tension detected by the tension sensor is too large, the threshold is corrected so that the tension becomes small. When the tension detected by the tension sensor is too small, the threshold is corrected so that the threshold becomes large. 
     (6) The controller according to the present invention may further execute a determination process of determining whether the difference between the displacement distance and the unwinding length of the wire is within a safe value range, and may further execute a drive stop process of stopping the drive of the first drive source and the second drive source upon determining that the difference between the displacement distance and the unwinding length is not within the safe value range. 
     The controller stops the drive of the first drive source and the second drive source upon determining that the difference between the displacement distance and the unwinding length is not within the safe value range. That is, when a problem occurs in winding of the wire by the winch, raising and lowering of the boom and rotation of the winch are stopped. Accordingly, it is possible to prevent the boom device and the wire from being hindered. 
     (7) The specified values may be the length of the boom and a separation distance between the derrick fulcrum of the boom and the engaging member. 
     (8) The specified values may be the length of the boom, a first separation distance in a horizontal direction between the derrick fulcrum of the boom and the engaging member, and a second separation distance in a vertical direction between the derrick fulcrum of the boom and the engaging member. 
     (9) The memory may store a class that generates a function for calculating the displacement distance based on the derrick angle and the unwinding length of the wire. The controller according to the present invention generates the function based on the class by using the specified values read out from the memory. 
     The controller uses a class to generate a function. Therefore, the controller can easily generate a function corresponding to the type of the boom device. 
     (10) The present invention can also be regarded as a boom device provided with the above-mentioned controller. 
     (11) The present invention can also be regarded as a crane vehicle including a boom device provided with the above-mentioned controller and a traveling body mounted with the boom device. 
     According to the present invention, it is possible to provide a controller that can automatically store or raise a boom and can be commonly used for various boom devices. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a crane vehicle  10  according to the present embodiment, showing a state where a boom  32  is at a storage position. 
         FIG. 2  is a diagram showing the crane vehicle  10  in a state where a boom  42  is at a raised position. 
         FIG. 3  is a functional block diagram of the crane vehicle  10 . 
         FIG. 4  is a flowchart of a boom raising process. 
         FIG. 5  is a flowchart of a boom storage process. 
         FIG. 6  is an explanatory diagram illustrating a displacement distance X(θ). 
         FIG. 7  is another explanatory diagram illustrating the displacement distance X(θ). 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings as appropriate. Needless to say, the present embodiment is merely one aspect of the present invention, and the embodiments may be changed without changing the gist of the present invention. 
       FIG. 1  is a schematic diagram showing a crane vehicle  10  according to the present embodiment. The crane vehicle  10  mainly includes a traveling body  11 , a boom device  12  mounted on the traveling body  11 , and a cabin  13 . 
     The traveling body  11  includes a vehicle body  20 , axles  21 , an engine  22  ( FIG. 4 ), and a battery  23  ( FIG. 4 ). 
     The vehicle body  20  rotatably supports the axles  21 . Wheels are attached to both ends of the axles  21 . The engine  22  rotates and drives the axles  21 . The engine  22  charges the battery  23 . 
     The engine  22  drives an oil hydraulic pump (not shown) included in an oil hydraulic supply device  24  described later. The oil hydraulic pump discharges operating oil at a predetermined pressure and drives a swivel motor  25 , a derrick cylinder  36 , a telescopic cylinder  37 , and an oil hydraulic motor  38  that are shown in  FIG. 4  and other actuators (hereinafter, also referred to as the swivel motor  25  and the like). 
     The vehicle body  20  is mounted with the oil hydraulic supply device  24  shown in  FIG. 4 . The oil hydraulic supply device  24  includes a solenoid valve and the like. The solenoid valve is opened and closed by a drive signal input from a controller  50  ( FIG. 4 ) described later. The swivel motor  25  and the like are driven by opening and closing the solenoid valve. That is, the controller  50  controls the drive of the swivel motor  25  and the like by outputting a drive signal for opening and closing the solenoid valve. In the present embodiment, an example in which the swivel motor  25  and the like are oil hydraulic actuators is described, and all or a part of the swivel motor  25  and the like may be an electric actuator or the like. 
     As shown in  FIG. 1 , the cabin  13  is mounted on a swivel base  31  of the boom device  12 . The cabin  13  includes a driving device  14  ( FIG. 3 ) configured to drive the crane vehicle  10 , and a manipulating device  15  ( FIG. 3 ) configured to manipulate the boom device  12 . That is, the crane vehicle  10  is a rough terrain crane, and driving of the crane vehicle  10  and manipulating of the boom device  12  are performed in one cabin  13 . However, the crane vehicle  10  may be an all-terrain crane including two cabins, that is, a cabin including the driving device  14  and a cabin including the manipulating device  15 . 
     The manipulating device  15  includes an operation lever, an operation button, and the like for operating the boom device  12 . The manipulating device  15  outputs an operation signal indicating a direction and an amount of operation of the operation lever and an operation signal indicating whether the operation button is operated. The operation signal output by the manipulating device  15  is input to the controller  50  ( FIG. 3 ). 
     The cabin  13  includes a control box (not shown). The control box includes a control board. The control board is mounted with a microcomputer, a resistor, a capacitor, a diode, and various ICs, and constitutes the controller  50  and a power supply circuit  17  shown in  FIG. 3 . 
     As shown in  FIG. 1 , the boom device  12  includes the swivel base  31  rotatably supported by the vehicle body  20  and a boom  32  supported by the swivel base  31 . The boom  32  includes a proximal boom  33 , one or more intermediate booms  34 , and a distal boom  35 . The proximal boom  33 , the intermediate boom  34 , and the distal boom  35  are arranged in a nested manner, and the boom  32  is telescopic. The proximal boom  33  is supported by the swivel base  31  such that the proximal boom  33  can be raised and lowered. That is, the boom  32  can be raised and lowered and is telescopic. The swivel base  31  corresponds to the “base” in the claims of the present invention. 
     The boom  32  is extended and retracted from a retracted state shown in  FIG. 1  to an extended state (not shown). The boom  32  is raised and lowered from a lowered position shown in  FIG. 1  to a raised position shown in  FIG. 2 . The crane vehicle  10  travels in a storage state where the boom  32  is in the retracted state and at the lowered position. 
     As shown in  FIG. 3 , the boom device  12  further includes the swivel motor  25 , the derrick cylinder  36  configured to raise and lower the boom  32 , and the telescopic cylinder  37  configured to extend and retract the boom  32 . 
     The swivel motor  25  is provided on the vehicle body  20 . The swivel motor  25  is rotated by being supplied with the operating oil from the oil hydraulic supply device  24  so as to swivel the swivel base  31 . 
     The derrick cylinder  36  is provided on the swivel base  31 . The telescopic cylinder  37  is provided on the boom  32 . The derrick cylinder  36  and the telescopic cylinder  37  are extended and retracted by being supplied with the operating oil from the oil hydraulic supply device  24 . The derrick cylinder  36  that is extended and retracted raises and lowers the boom  32 . The telescopic cylinder  37  that is extended and retracted extends and retracts the boom  32 . A swivel joint (not shown) is provided between the vehicle body  20  and the swivel base  31 . The oil hydraulic supply device  24  provided on the vehicle body  20  supplies the operating oil to the derrick cylinder  36  and the telescopic cylinder  37  via the swivel joint. The derrick cylinder  36  corresponds to the “first drive source” and the “cylinder” in the claims of the present invention. 
     The boom device  12  further includes the oil hydraulic motor  38 , a winch  39 , a load hook  40 , and an engaging member  41 . The oil hydraulic motor  38  is rotated by being supplied with the operating oil from the oil hydraulic supply device  24  via the swivel joint. A rotation speed of the oil hydraulic motor  38  is controlled by the controller  50 . The rotating oil hydraulic motor  38  rotates a wire drum  29  of the winch  39 . The rotating wire drum  29  winds up a wire  42  or unwinds the wire  42 . The oil hydraulic motor  38  corresponds to the “second drive source” in the claims of the present invention. 
     The wire  42  is connected to the load hook  40 . The load hook  40  is suspended by the wire  42  from a distal end of the boom  32 . The load hook  40  rises and falls as the winch  39  rotates. 
     The engaging member  41  is a member that engages with the load hook  40  to fix the load hook  40 . The engaging member  41  is fixed to the swivel base  31 . The engaging member  41  is located right below the distal end of the boom  32  at the raised position and in the retracted state. The engaging member  41  fixes the load hook  40  such that the load hook  40  does not move while the crane vehicle  10  is traveling. 
     The boom  32  further includes a length sensor  26  configured to detect an unwinding length of the wire  42 , and a derrick angle sensor  27  configured to detect a derrick angle of the boom  32 . A tension sensor  28  shown in  FIG. 3  will be described in a modified example. 
     The length sensor  26  and the derrick angle sensor  27  are used for a boom raising process and a boom storage process which will be described later. 
     The length sensor  26  is, for example, a rotary encoder configured to detect an amount of rotation of the winch  39 . The length sensor  26  outputs a pulse signal whose voltage value changes according to rotation of the winch  39 . The length sensor  26  is connected to the controller  50  by a signal line such as a cable. The controller  50  calculates the unwinding length of the wire  42  based on the number of pulses input from the length sensor  26 . However, any kind of sensor may be used for the length sensor  26  as long as the sensor can detect the unwinding length of the wire  42 . 
     Existing optical or magnetic sensors that output a voltage value corresponding to the derrick angle of the boom  32  and rotary encoders are used as the derrick angle sensor  27 . The derrick angle sensor  27  is connected to the controller  50  by a signal line such as a cable. The controller  50  calculates the derrick angle of the boom  32  based on a signal voltage output by the derrick angle sensor  27 . For example, the controller  50  calculates the derrick angle of the boom  32  with reference to a position of the boom  32  at a storage position. In the following, the derrick angle of the boom  32  calculated by the controller  50  is also referred to as a “detected derrick angle”. 
     The power supply circuit  17  is a circuit configured to generate electric power to be supplied to the controller  50  and the like. The power supply circuit  17  is, for example, a DC-DC converter. The power supply circuit  17  converts a DC voltage supplied from the battery  23  into a DC voltage having a predetermined stable voltage value and outputs the DC voltage. 
     The controller  50  includes a central processing unit  51  (CPU) and a memory  52 . The memory  52  includes, for example, a ROM, a RAM, an EEPROM and the like. 
     The memory  52  stores an operating system  53  (OS), a control program  54  for controlling the drive of the boom device  12 , specified values, a first threshold, a second threshold, and a safe value. The OS  53  and the control program  54  are executed by the CPU  51  in a pseudo-parallel manner by a multi-task process. 
     The specified values refer to “L”, “D”, and “φ” shown in  FIG. 6 . “L” is the length of the boom  32  from a proximal end to the distal end. The proximal end of the boom  32  is a position of the derrick fulcrum P of the boom  32 . The distal end of the boom is, for example, a mounting position of a member around which the wire  42  is wound. “D” is a distance from the derrick fulcrum P of the boom  32  to the load hook  40 . “φ” is a depression angle of the load hook  40  with respect to the derrick fulcrum P of the boom  32 . The specified values are stored in the memory  52  in advance according to the type of the boom device  12 . “D” corresponds to the “separation distance” in the claims of the present invention. 
     The first threshold, the second threshold, and the safe value are used for a determination process in the boom raising process and the boom storage process which will be described later. Details will be described later. The first threshold and the second threshold correspond to the “threshold” in the claims of the present invention. 
     The CPU  51 , the memory  52 , the above-mentioned length sensor  26 , the derrick angle sensor  27 , and the like are connected to a communication bus (not shown). The control program  54  executed by the CPU  51  reads a function, the first threshold, and the second threshold from the memory  52  through the communication bus, receives a detected signal output from the length sensor  26  and the derrick angle sensor  27 , and writes and stores information and data in the memory  52 . 
     The control program  54  has a class. That is, the class is stored in the memory  52 . The class creates an instance (object). Specifically, the class generates a function X(θ) as an instance by being given the specified values stored in the memory  52 . The function X(θ) is a calculation formula for calculating a displacement distance X(θ) {θ: detected derrick angle}, which is a distance from the distal end of the boom  32  to the load hook  40 , using the detected derrick angle θ of the boom  32 . The control program  54  feedback-controls the drive of the boom device  12  such that a difference between the displacement distance X(θ) and an unwinding length S of the wire  42  detected by the sensor  26  is equal to or larger than the first threshold and less than the second threshold. Details will be described later. The method for generating the function X(θ) is not limited to those using a class. Other methods may be used as long as the method can generate the function X(θ) based on the specified values. 
     The control program  54  is a program for executing the boom raising process of automatically raising the boom  32  stored in the storage state ( FIG. 1 ) to the raised position ( FIG. 2 ) and the boom storage process of automatically lowering the boom  32  at the raised position to the storage state to storage the boom  32 . The boom raising process is an example of an automatic boom drive process. The boom storage process is an example of the automatic boom drive process. 
     More specifically, after the crane vehicle  10  arrives at a work site, an operator makes the control program  54  execute the boom raising process. That is, the boom raising process is a process executed for the crane vehicle  10  to start a work at the work site. 
     The operator makes the control program  54  execute the boom storage process so that the crane vehicle  10  travels away from the work site. That is, the boom storage process is a process executed for the crane vehicle  10  to complete the work at the work site. 
     The boom raising process is a process in which the control program  54  automatically performs a raising operation of the boom  32 , which has been manually performed by the operator using the manipulating device  15 . The boom storage process is a process in which the control program  54  automatically performs a storage operation of the boom  32 , which has been manually performed by the operator using the manipulating device  15 . Hereinafter, the boom raising process and the boom storage process will be described in detail with reference to  FIGS. 4 and 5 . An execution order of steps executed by the control program  54  in the boom raising process and the boom storage process may be changed as long as the execution order does not change the gist of the present invention. 
     After the crane vehicle  10  arrives at the work site, the operator uses the manipulating device  15  to perform an operation instructing execution of the boom raising process. As shown in  FIG. 1 , when the crane vehicle  10  arrives at the work site, the boom  32  is retracted and lowered down, and the load hook  40  is fixed to the engaging member  41 . The boom raising process is executed with the load hook  40  fixed to the engaging member  41  such that the load hook  40  does not move in the boom raising process. 
     The control program  54  starts to execute the boom raising process shown in  FIG. 4  in response to input of an operation signal instructing the execution of the boom raising process from the manipulating device  15 . First, the control program  54  extends the derrick cylinder  36  at a constant speed (S 11 ). Alternatively, the control program  54  extends the derrick cylinder  36  such that the boom  32  is raised at a constant angular velocity (dθ/dt=constant). More specifically, the control is more complicated if the control program  54  has two drive systems to be subjected to feedback control. The control program  54  extends the derrick cylinder  36  at a constant speed or a constant angular velocity for ease of control. The boom  32  is gradually raised as the derrick cylinder  36  is extended at a constant speed or a constant angular velocity. 
     Next, the control program  54  rotationally drives the winch  39  at an initial rotation speed V 1  (S 12 ). The direction of rotation of the winch  39  is a direction to which the wire  42  is unwound. That is, the wire  42  is gradually unwound while the boom  32  is gradually raised. 
     Next, the control program  54  reads the specified values L, D, and φ from the memory  52 , and uses the read specified values and the class stored in the memory  52  to generate the function X(θ) that is an instance (S 13 ). Then, the control program  54  differentiates the generated function X(θ) with respect to a time t, and calculates a time change of the function X (θ), that is, a unwinding speed V(t) of the wire  42 . The differentiation of the function X(θ) may be performed by a differentiating circuit using an operational amplifier. 
       FIG. 6  shows d(X(θ))/dt obtained by differentiating the function X(θ) with respect to the time t. “de/dt” in the figure is a time change of the derrick angle θ of the boom  32 , that is, the angular velocity of the boom  32 . When the control program  54  raises the boom  32  at a constant angular velocity, “de/dt” in the figure is a constant. The constant “de/dt” is stored in the memory  52  in advance. Further, when the control program  54  extends the derrick cylinder  36  at a constant speed, “de/dt” is stored in the memory  52  in advance or calculated by the control program  54 . The control program  54  calculates the unwinding speed V(t) of the wire  42  by using the calculated “de/dt” or “de/dt” stored in the memory  52 . 
     Next, the control program  54  calculates an unwinding speed dS/dt of the wire  42  based on the detected signal input from the length sensor  26  (S 15 ). For example, the control program  54  acquires the detected signals output by the length sensor  26  per unit time, and calculates a differential in the lengths of the wire  42  indicated by the acquired detected signals. The differential is the length of the wire  42  per unit time, that is, the unwinding speed dS/dt of the wire  42 . The control program  53  calculates the actual unwinding speed dS/dt of the wire  42  by calculating the above-mentioned differential. 
     Then, the control program  54  calculates a difference Z=“V(t)−dS/dt” between the unwinding speed V(t) of the wire  42  calculated as a calculated value and the actual unwinding speed dS/dt of the wire  42 , and determines whether the calculated Z is less than the first threshold (S 16 ). That is, in step S 16 , whether the unwinding speed of the wire  42  is too high is determined. 
     If the control program  54  determines that Z is less than the first threshold (S 16 : Yes), that is, it determines that the unwinding speed of the wire  42  is too high, the control program  54  reduces a rotation speed of the winch  39  (S 17 ). Specifically, the control program  54  reduces the rotation speed of the oil hydraulic motor  38  from the initial value V 1  according to the magnitude of the value of Z. In contrast, if the control program  54  determines that Z is equal to or larger than the first threshold (S 16 : No), the control program  54  skips the process of step S 17 . 
     Next, the control program  54  determines whether the value of Z is equal to or larger than the second threshold (S 18 ). That is, in step S 18 , whether the unwinding speed of the wire  42  is too low is determined. 
     If the control program  54  determines that the value of Z is equal to or larger than the second threshold (S 18 : Yes), that is, it determines that the unwinding speed of the wire  42  is too low, the control program  54  increases the rotation speed of the winch  39  (S 19 ). Specifically, the control program  54  increases the rotation speed of the oil hydraulic motor  38  from the initial value V 1  according to the magnitude of the value of Z. In contrast, if the control program  54  determines that the value of Z is less than the second threshold (S 18 : No), the control program  54  skips the process of step S 19 . 
     The first threshold and the second threshold are set to values such that a tension T applied to the wire  42  is less than a predetermined value and the wire  42  does not loosen in the process in which the wire  42  is gradually unwound while the boom  32  is gradually raised. That is, the control program  54  feedback-controls the derrick cylinder  36  and the oil hydraulic motor  38  such that the tension T applied to the wire  42  is less than the predetermined value and the wire  42  does not loosen. 
     Next, the control program  54  determines whether an absolute value of Z is less than the safe value stored in the memory  52  (S 20 ). The safe value is a value larger than the first threshold and the second threshold. That is, in step S 20 , it is determined in the winch  39  whether a problem has occurred in the unwinding of the wire  42  or whether a problem has occurred in the rotation of the winch  39 . The process of step S 20  corresponds to the “determination process” in the claims of the present invention. 
     If the control program  54  determines that the absolute value of Z is equal to or larger than the safe value stored in the memory  52  (S 20 : No), the control program  54  stops driving the derrick cylinder  36  and the oil hydraulic motor  38  (S 21 ). That is, the control program  54  stops the boom  32  and the winch  39 . Then, the control program  54  executes a notification process (S 22 ). For example, the control program  54  makes a speaker output a warning sound, or makes a monitor provided in the manipulating device  15  display a warning screen. The process of step S 21  corresponds to the “drive stop process” in the claims of the present invention. 
     Next, the control program  54  determines whether the detected derrick angle θ is equal to or larger than α (S 23 ). α is a value of θ when the boom  32  is at the raised position, and is stored in the memory  52  in advance. That is, in step S 23 , it is determined whether the boom  32  has arrived at the raised position. The control program  54  repeatedly executes the processes from step S 16  to step S 20  until the boom  32  arrives at the raised position and the detected derrick angle θ has reached α (S 23 : No). 
     If the control program  54  determines that the boom  32  has arrived at the raised position and the detected derrick angle θ has reached α (S 23 : Yes), the control program  54  stops the drive of the derrick cylinder  36  and the oil hydraulic motor  38  (S 24 ), and ends the boom raising process. 
     Next, the boom storage process will be described with reference to  FIG. 5 . The same process as the boom raising process is given the same step number as the step number associated with the boom raising process, and the description thereof is omitted. 
     When the operator finishes the work of the crane vehicle  10 , the operator first uses the manipulating device  15  to make the boom  32  in the retracted state and make the boom  32  at the raised position as shown in  FIG. 2 . Then, the operator engages the load hook  40  with the engaging member  41  to fix the load hook  40  with the engaging member  41 . After that, the operator uses the manipulating device  15  to perform an operation instructing the execution of the boom storage process. 
     The control program  54  starts to execute the boom storage process shown in  FIG. 5  in response to input of an operation signal instructing the execution of the boom storage process from the manipulating device  15 . First, the control program  54  retracts the derrick cylinder  36  at a constant speed (S 31 ). As the derrick cylinder  36  is retracted at a constant speed, the boom  32  is gradually lowered. 
     Next, the control program  54  rotationally drives the winch  39  at an initial rotation speed V 2  (S 32 ). The direction of rotation of the winch  38  is a direction to which the wire  42  is wound up. That is, the wire  42  is gradually wound up while the boom  32  is gradually lowered. The initial rotation speed V 2  may be the same as the initial rotation speed V 1  or different from the initial rotation speed V 1 . 
     Next, the control program  54  executes processes from steps S 13  to S 22  in the same manner as the boom raising process. That is, the control program  54  performs feedback control to gradually lower the boom  32  and to gradually wind up the wire  42  in a manner such that the tension T applied to the wire  42  is less than a predetermined value and the wire  42  does not loosen. 
     Next, the control program  54  determines whether the detected derrick angle θ is equal to or less than β (S 33 ). β is a value of 0 when the boom  32  is at the lowered position, and is stored in the memory  52  in advance. β is, for example, “0”. That is, in step S 33 , it is determined whether the boom  32  has arrived at the lowered position. The control program  54  repeatedly executes the processes from steps S 16  to S 20  until the boom  32  arrives at the lowered position and the detected derrick angle θ reaches β (S 33 : No). 
     If the control program  54  determines that the boom  32  has arrived at the lowered position and the detected derrick angle θ has reached β (S 33 : Yes), the control program  54  stops the drive of the derrick cylinder  36  and the oil hydraulic motor  38  (S 24 ), and ends the boom storage process. 
     Operation and Effect of Embodiment 
     In the present embodiment, the control program  54  executes the boom raising process and the boom storage process, so that the raising operation of the boom  32  and the storage operation of the boom  32  can be automatically performed. Therefore, the work of the operator is facilitated in the raising operation of the boom  32  and the storage operation of the boom  32 , and it is possible to prevent “irregular winding” in the winch  39 , and further, it is possible to prevent the boom device  12  from being damaged. More specifically, the operator must operate two operating targets, the boom  32  and the winch  39  when manually performing the raising operation of the boom  32  and the storage operation of the boom  32 . That is, the operator operates the winch  39  while the raising and lowering the boom  32  and monitoring a tension state of the wire  42 . The operation requires the mastery skill of the operator. If the operator makes a mistake in the operation, excessive tension acts on the wire  42 , which may damage the engaging member  41  and the winch  39 . Further, if the operator makes a mistake in the operation, the wire  42  may loosen, causing the “irregular winding” in the winch  39 . In the present embodiment, the control program  54  executes the boom raising process and the boom storage process, so that the work of the operator is facilitated, and it is possible to prevent the “irregular winding” from occurring in the winch  39 , and further, it is possible to prevent the boom device  12  from being damaged. 
     The control program  54  generates the function X(θ) using the specified values stored in the memory  52 , and calculates the displacement distance X(θ) {θ: detected derrick angle} from the distal end of the boom  32  to the engaging member  41  using the generated function (θ). Then, the control program  54  performs feedback control using the calculated displacement distance X(θ). Therefore, since the specified values read out from the memory  52  are changed depending on the type of the boom device  12 , the controller  50  can be commonly used with various boom devices  12 . Accordingly, the controller  50  with high versatility can be realized. 
     In the present embodiment, since the control program  54  extends and retracts the derrick cylinder  36  at a constant speed (S 11  and S 31 ), the target of feedback control may be limited to the oil hydraulic motor  38  of the winch  39 . Accordingly, the control program  54  can easily control the boom device  12 . Further, in the boom  32  which is visible to the operator, if a derrick speed fluctuates little by little, the operator may be anxious. In the present embodiment, since the derrick cylinder  36  is extended and retracted at a constant speed, the derrick speed of the boom  32  does not fluctuate little by little, which gives the operator a sense of security. 
     In the present embodiment, the control program  54  stops the boom  32  and the winch  39  upon determining that the absolute value of the difference between the displacement distance X(θ) and the unwinding length S of the wire  42  is equal to or larger than the safe value. Therefore, it is possible to prevent the boom device  12  from failing or the wire  42  from being damaged. 
     In the present embodiment, the control program  54  generates the function X(θ) using the specified values L, D, and φ read out from the memory  52 , and the class, and calculates the displacement distance X(θ) {θ: detected derrick angle} using the generated function X(θ). Therefore, in step S 14 , the displacement distance X(θ) can be calculated without reading the specified values L, D, and φ from the memory  52 . Therefore, the number of times of reading the specified values L, D, and φ from the memory  52  can be reduced. Accordingly, the speed of processes from steps S 14  to S 19  is increased. Since the speed of the processes is increased, the feedback control can be performed in a period shorter than the case when the specified values L, D, and φ are sequentially read out from the memory  52  to calculate the displacement distance X(θ). Accordingly, it is possible to further prevent the “irregular winding” from occurring in the winch  39 , and further prevent the boom device  12  from being damaged. 
     [Modification] 
     In the present modification, an example in which the tension T applied to the wire  42  is detected and the first threshold and the second threshold are corrected based on the detected tension T will be described. 
     The boom device  12  further includes the tension sensor  28  as shown in  FIG. 3 . The tension sensor  28  is a sensor configured to output a detected signal of the voltage value corresponding to the tension T applied to the wire  42 . The tension sensor  28  is, for example, a load cell. 
     The tension sensor  28  is connected to the controller  50  by a signal line such as a cable. The detected signal output by the tension sensor  28  is input to the controller  50 . The controller  50  determines the tension T applied to the wire  42  by the detected signal input from the tension sensor  28 . Then, the controller  50  corrects or re-determines the first threshold and the second threshold stored in the memory  52  based on the determined tension T. Specifically, the memory  52  stores in advance a correction formula for correcting the first threshold and the second threshold from the tension T, or a correspondence table in which the tension T is associated with the first threshold and the tension T is associated with the second threshold. The controller  50  corrects or re-determines the first threshold and the second threshold by using the determined tension T and the above-mentioned correction formula, or by using the determined tension T and the above-mentioned correspondence table. Re-determination of the first threshold and the second threshold is also included in the correction of the first threshold and the second threshold. 
     For example, when the tension T detected by the tension sensor  28  is larger than a first determination value stored in the memory  52 , the second threshold is corrected or re-determined so that the second threshold becomes small. The tension T applied to the wire  42  decreases when the second threshold becomes small. Further, when the tension T detected by the tension sensor  28  is smaller than a second determination value stored in the memory  52  and the wire  42  is not sufficiently stretched, the first threshold is corrected or re-determined so that the first threshold becomes large. The wire  42  is stretched with an appropriate tension T when the first threshold becomes large. 
     The controller  50  executes the determination processes of step S 16  and step S 18  by using the corrected or re-determined first threshold and second threshold. Other processes are the same as those of the embodiment. 
     [Operation and Effect of Modification] 
     In the present modification, the magnitude of the tension T applied to the wire  42  can be controlled more appropriately by correcting the first threshold and the second threshold by the tension of the wire  42  detected by the tension sensor  28 . 
     [Other Modifications] 
     In the above-mentioned embodiment, an example in which the specified values are “L”, “D”, and “φ” has been described. However, the specified values are not limited to “L”, “D”, and “φ”. The specified values may be “L”, “φ”, “a”, and “b” as shown in  FIG. 7 . The specified value “D” can be replaced with the specified values “a” and “b”. Specifically, “D” can be replaced with “a” and “b” as “D squared”=“a squared”+“b squared”. “a” corresponds to the “first separation distance” in the claims of the present invention. “b” corresponds to the “second separation distance” in the claims of the present invention. 
     In the above-mentioned embodiment and modifications, an example in which “φ” is included in the specified values has been described. However, “φ” can be excluded from the specified values with the derrick angle θ used as an elevation angle from the engaging member  42 . That is, “T” is excluded from the specified values with θ+φ used as a new θ. 
     In the above-mentioned embodiment, an example in which the derrick cylinder  36  is extended and retracted at a constant speed in steps S 11  and S 31  has been described. However, the drive of the derrick cylinder  36  may be controlled such that the boom  32  is raised and lowered at a constant speed. 
     In the above-mentioned embodiment, an example in which the derrick cylinder  36  is extended and retracted at a constant speed and the oil hydraulic motor  38  of the winch  39  is feedback-controlled has been described. However, the winch  39  may be rotated at a constant rotation speed, and the derrick cylinder  36  of the boom  32  may be feedback-controlled. 
     In the above-mentioned embodiment, an example in which the drive of the winch  39  is feedback-controlled such that the difference Z between the unwinding speed of the wire  42  and the actual unwinding speed of the wire  42  detected by the length sensor  26  is within a range indicated by the second threshold has been described. However, the drive of the winch  39  may be feedback-controlled such that the difference between the unwinding length of the wire  42  and the actual unwinding length of the wire  42  detected by the length sensor  26  is within the threshold range. Also in this case, it is possible to prevent the “irregular winding” from occurring in the winch  39 , and further prevent the boom device  12  from being damaged.