Transport system

Abstract

Provided is a transport system that lowers a suspension implement to an appropriate height and can thereby keep a robot device from being overloaded.　A transport system 10 comprises a hoist 2, a suspension implement 4 that is to suspend a workpiece Wo, a robot device 3 that moves the suspension implement 4, and a crane 1 that causes the hoist 2 to track. The hoist 2 comprises a drive motor 26 that causes a winding part 25 that performs raising and lowering to rotate and a motor control unit 20c that controls the torque of the drive motor 26 on the basis of the load torque applied to the winding part 25 and has a first torque control mode in which the torque of the drive motor 26 is controlled to balance a prescribed reference torque and a load obtained by subtracting the upward holding force of the robot device 3 from the weight of the suspension implement 4 and a second torque control mode in which the drive motor 26 is controlled to a lower torque than in the first torque control mode. The motor control unit 20c selects the second torque control mode when the suspension implement 4 is lowered toward the workpiece Wo.

Description

Transport System

[0001] The present invention relates to a transport system.

[0002] Patent Document 1 discloses a transport system that transports a workpiece by using a hanging device and a robot device in cooperation with each other. The hanging device includes a support mechanism, a lifting unit, and a hanging jig. Since the load of the hanging jig is greater than the load that the robot device can transport, the transport system reduces the load on the robot device by having the hanging device bear the large load of the workpiece and the load of the hanging jig.

[0003] Furthermore, in order to prevent the weight of the hanging jig and / or workpiece from being applied to the robot device, a mechanism that allows relative movement in the vertical direction is provided at the joint between the hanging jig and the workpiece.

[0004] JP 2014-128860 A

[0005] If a mechanism that allows relative movement in the vertical direction is provided at the joint between the robot device and the hanging jig or workpiece, the hanging device becomes complicated, which is a factor in increasing costs.

[0006] Furthermore, when a magnet is attached to the hanging jig, for example, and the magnet is lowered by a lifting unit to pick up the workpiece, the hanging device cannot grasp the height of the workpiece, making it difficult to set the amount of descent of the hanging jig to an appropriate value.

[0007] This can result in the hanging device descending too far, placing the weight of the hanging jig on the robot device, or insufficient descending causing a gap between the hanging jig and the workpiece, which can result in an impact load chucking the workpiece when picking it, potentially overloading the robot device.

[0008] Furthermore, when the hanging jig with the workpiece picked up is lowered to the placement surface, if the lowering distance is too great, the chain connecting the hanging jig to the bottom end may bend, which may result in an overload on the robot device. Also, if the lowering distance is insufficient and there is a gap between the workpiece and the placement surface when the workpiece is separated from the hanging jig, an impact load may be applied to the workpiece, which may result in damage.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a conveying system that can prevent an overload from being placed on a robot device by lowering a hoisting tool to an appropriate height without providing a mechanism that can move relatively in the vertical direction at the joint between the robot device and the hoisting jig or workpiece.

[0010] A transport system according to one aspect of the present invention includes a hoisting machine that lifts and lowers a hanging body to raise and lower a workpiece, a hoisting device that is connected to the lower end of the hanging body by a connecting member and suspends the workpiece, a robot device that is connected to the hoisting device and moves the hoisting device, and a crane that moves the hoisting machine to follow the movement of the hoisting device by the robot device so that the hoisting machine is positioned directly above the hoisting device, and the hoisting machine is disposed on a hoisting machine body and includes a winding unit that lifts and lowers the hanging body, a drive motor that generates a driving force to rotate the winding unit, a load calculation unit that calculates a load torque applied to the winding unit, and a load calculation unit. and a motor control unit that controls the torque of the drive motor in a torque control mode that performs torque control based on load torque, the torque control modes including a first torque control mode that controls the torque of the drive motor so that a predetermined reference torque is balanced with a load obtained by subtracting the upward holding force of the robot device from the weight of the lifting device, and a second torque control mode that controls the torque of the drive motor so that the torque is smaller by a predetermined value than the torque in the first torque control mode, and the motor control unit selects the second torque control mode when lowering the lifting device toward the workpiece.

[0011] A transport system according to one aspect of the present invention is a transport system including a hoist that lifts and lowers a hanging body to lift and lower a workpiece, a hoisting device that is connected to the lower end of the hanging body by a connecting member and suspends the workpiece, a robot device that is connected to the hoisting device or the workpiece and moves the hoisting device or the workpiece, and a crane that moves the hoisting device to follow and position itself directly above the hoisting device or the workpiece as the robot device moves the hoisting device or the workpiece, and the hoisting device is disposed on the hoisting device body and includes a winding unit that lifts and lowers the hanging body, a drive motor that generates a driving force to rotate the winding unit, and a load torque calculation unit that calculates the load torque applied to the winding unit. The robot includes a load calculation unit and a motor control unit that controls the torque of the drive motor in a torque control mode that performs torque control based on load torque. The torque control modes include a first torque control mode that controls the torque of the drive motor so that a predetermined reference torque is balanced with a load obtained by subtracting the upward holding force of the robot device from the sum of the weights of the hoisting device and the workpiece, and a second torque control mode that controls the torque of the drive motor so that the torque is smaller by a predetermined value than the torque in the first torque control mode. The motor control unit selects the second torque control mode when the hoisting device suspending the workpiece is lowered toward the release position.

[0012] A conveying system according to one aspect of the present invention comprises a hoist that raises and lowers a hanging body to raise and lower the workpiece, a hoisting device connected to the lower end of the hanging body by a connecting member and suspending the workpiece, a robot device connected to the hoisting device and moving the workpiece, and a crane that moves the hoisting machine to follow and position itself directly above the hoisting device as the robot device moves the hoisting device, the hoisting machine being disposed on the hoisting machine body and comprising a winding unit that hoists and lowers the hanging body, a drive motor that generates a driving force to rotate the winding unit, a load calculation unit that calculates the load torque applied to the winding unit, and a motor control unit that controls the torque of the drive motor in a torque control mode in which torque control is performed based on the load torque, the torque control mode controlling the drive motor based on a predetermined reference torque and load torque, the reference torque being set based on the load torque applied to the winding unit and the torque applied to the robot device.

[0013] According to the present invention, it is possible to provide a conveying system that can prevent the robot device from being overloaded by lowering the lifting tool to an appropriate height without providing a mechanism that can move relatively in the vertical direction at the joint between the robot device and the hanging jig or workpiece.

[0014] FIG. 1 is a configuration diagram showing the configuration of a conveying system according to a first embodiment. FIG. 2 is a configuration diagram showing the control configuration of a hoist. FIG. 3 is a configuration diagram showing the control configuration of a conveying system according to the first embodiment. FIG. 4 is a flowchart showing setting of a set load in float mode of the hoist. FIG. 5 is an operation table showing the operation of each component of the conveying system according to the first embodiment. FIG. 6 is a schematic diagram showing the state of each component of the conveying system according to the first embodiment when picking. FIG. 7 is a schematic diagram showing the state of each component of the conveying system according to the first embodiment when picking. FIG. 8 is a schematic diagram showing the state of each component of the conveying system according to the first embodiment when dropping. FIG. 9 is a schematic diagram showing the state of each component of the conveying system according to the first embodiment when dropping. FIG. 10 is an operation table showing the operation of each component of the conveying system according to a second embodiment. FIG. 11 is an operation table showing the operation of each component of the conveying system according to a third embodiment.

[0015] First Embodiment A transport system 10 according to a first embodiment will be described below with reference to the drawings.

[0016] [Transport System] [Structure] First, the structure of the transport system 10 will be described with reference to FIGS. 1, 2 and 3. FIG.

[0017] As shown in FIG. 1 , the transport system 10 includes a crane 1 , a hoisting machine 2 , a robot device 3 , a lifting device 4 , and a transport control unit 5 .

[0018] (Crane) The crane 1 has traveling rails 11 and lateral travel rails 12. The traveling rails 11 are two rail members that are, for example, suspended from a ceiling or the like. The lateral travel rails 12 are rail members that are, for example, suspended near both ends of the two traveling rails 11 via trolleys (not shown), and are movable along the longitudinal direction of the traveling rails 11.

[0019] The crane 1 is a horizontal movement device that follows the horizontal movement of the lifting device 4 by the robot device 3 and moves the hoisting machine main body 22 horizontally so that the hoisting machine main body 22 is always positioned almost directly above the hoisting device 4.

[0020] (Hoist) The hoist 2 can be raised and lowered with the hoisting device 4, which will be described later, suspended from it. Furthermore, the lateral travel rails 12 are freely movable along the traveling rails 11, and the hoisting device 2 is also freely movable along the lateral travel rails 12, so that the hoisting device 2 can move freely in the horizontal direction. Therefore, even if the hoisting device 4, which will be described later, is moved horizontally by the robot device 3, the hoisting device 2 can follow the movement and always be positioned above the hoisting device 4.

[0021] (Lifting Device) The lifting device 4 has a connecting member 41 fixed via a shackle 43 or the like to the lower hook 21 at the lower end of the load chain Cl serving as a hanging body, and a suction part 42 disposed below the connecting member 41 and capable of suctioning a workpiece Wo (not shown). The suction part 42 has a rotation shaft 44 extending horizontally and is fixed to the lower end of the connecting member 41 in a state where it can rotate about the rotation shaft 44.

[0022] Robot device 3 is a human-collaborative robot that is composed of leg 31, three joints 32, 33, and 34, and three arms 35, 36, and 37, with hand 37a of arm 37 at the tip connected to connecting member 41 of sling 4. Robot device 3 moves sling 4 to a desired position by operating joints 32, 33, and 34 and arms 35, 36, and 37.

[0023] (Robot Device) The robot device 3 has a leg 31, a first joint 32, a second joint 33, a third joint 34, a first arm 35, a second arm 36, and a third arm 37. As shown in Fig. 3 , the leg 31 has a first motor 31a, the first joint 32 has a second motor 32a, the second joint 33 has a third motor 33a, the third joint 34 has a fourth motor 34a, the first arm 35 has a fifth motor 35a, and the second arm 36 has a sixth motor 36a.

[0024] 1 , the leg 31 is erected upward from an installation surface such as a floor, and rotatably supports the first joint 32. The leg 31 houses a first motor 31 a therein, and by driving the first motor 31 a, the first joint 32 in contact with the leg 31 can be rotated about an axis perpendicular to the installation surface (hereinafter referred to as the “V axis”).

[0025] The first joint 32 is provided on the upper end side of the leg 31, and the first arm 35 is rotatably attached to the first joint 32. The first joint 32 has a second motor 32a. The second motor 32a rotates the first arm 35 around an axis parallel to the installation surface (hereinafter referred to as the "H axis"). Therefore, the first arm 35 can rotate around the V axis by the leg 31, and can also rotate around the H axis by the first joint 32.

[0026] The second joint 33 is rotatably attached to the tip end of the first arm 35, and the second arm 36 is rotatably attached to the second joint 33. The second joint 33 has a third motor 33a. The third motor 33a rotates the second arm 36 around the H-axis. Therefore, the second arm 36 can rotate around the V-axis by the leg 31, and can also rotate around the H-axis using the second joint 33 as the center.

[0027] The third joint 34 is rotatably attached to the tip end of the second arm 36, and the third arm 37 is rotatably attached to it. The third joint 34 has a fourth motor 34a. The fourth motor 34a rotates the third arm 37 about the H-axis, always maintaining the third arm 37 at the same angle so that it extends vertically. The third arm 37 has a hand 37a, and detachably holds the connecting member 41 of the sling 4 by a magnetic or air-based actuator (not shown).

[0028] 3, the torque sensors 31b to 36b are incorporated into the output sections of the motors 31a to 36a of the robot device 3, and transmit the torques applied to the motors 31a to 36a of the robot device 3 to the robot control unit 30. Note that the torque sensors 31b to 36b may be replaced by external force sensors such as strain gauges that are provided on the side surfaces of the joints 32 to 34 and the arms 35 and 36.

[0029] To ensure the safety of the system, when an unexpected external force is applied to the robot device 3, the torque sensors 31b to 36b detect the external force and immediately stop the robot device 3. When the robot device 3 detects the external force, a notification to that effect is sent to the transport control unit 5, which immediately stops the operation of the crane 1 and hoist 2.

[0030] The load applied to the tip of the hand unit 37a of the robot device 3 can be calculated by utilizing the detection values ​​of the torque sensors 31b to 36b incorporated in the robot device 3 and calculating the resultant force of the detection values. In other words, the load applied to the tip of the hand unit 37a can be calculated by utilizing the safety function originally provided in the robot device 3, as described above.

[0031] (Transport Control Unit) The transport control unit 5 (FIG. 3) receives an operation command from a worker and controls the transport of the workpiece Wo by transmitting a signal to the hoisting machine 2 and the robot device 3. The detailed control content of the transport control unit 5 will be described later.

[0032] (Control Configuration of Hoist) As shown in FIG. 2 , the hoist 2 includes a hoist body 22, an upper hook 23, a chain bucket 24 that holds the wound-up load chain Cl, and a lower hook 21.

[0033] The chain bucket 24 stores and holds the load chain Cl on the unloaded side that has been wound around the load sheave 25 as a winding section.

[0034] The lower hook 21 is connected to the lower end of the load side of the load chain Cl and is an attachment device that engages with the lifting tool 4, which can attach and detach a workpiece Wo (not shown) to be lifted by the hoist 2.

[0035] The hoisting machine main body 22 can be suspended from a predetermined location such as a ceiling via an upper hook 23. The hoisting machine main body 22 includes, inside a housing, a drive motor 26, a speed reduction mechanism 27, a brake mechanism 28, a load sheave 25 that winds up the load chain Cl, a load sensor 22a, a driver 29, and a hoisting machine control unit 20.

[0036] The drive motor 26 is a motor that provides driving force to drive the load sheave 25. The drive motor 26 is a servo motor equipped with an encoder 26a that can output position information for detecting the payout length of the load chain Cl, and is preferably an AC servo motor. Note that the AC servo motor is preferably a synchronous motor, but the drive motor 26 may also be a combination of an induction motor and an encoder that are drive-controlled by an inverter control device.

[0037] The speed reduction mechanism 27 reduces the speed of the rotation of the drive motor 26 and transmits it to the load sheave 25. The brake mechanism 28 uses electromagnetic force to release the braking force when the drive motor 26 is operating, and generates braking force to hold the hoisting tool 4 that has adsorbed the workpiece Wo when the drive motor 26 is not operating.

[0038] The load sheave 25 rotates to wind up and lower the load chain Cl. The load sheave 25 has a plurality of chain pockets (not shown) along its outer periphery into which the metal rings of the load chain Cl fit.

[0039] The load sensor 22a measures the load applied to the upper hook 23. The load sensor 22a measures and detects the total load of the load on the hoist main body 22, the load on the load chain Cl, and the load on the workpiece Wo. The hoist control unit 20 calculates the tension of the load chain C1, which is the load applied to the load sheave 25 via the load chain Cl, by subtracting the main body weight, etc. from the total load measured and detected using the load sensor 22a.

[0040] The load sensor 22a is attached, for example, to a mounting shaft for mounting the upper hook 23 to the hoisting machine body 22. In this embodiment, the load sensor 22a is a load cell equipped with a strain gauge.

[0041] In addition to the above, the load sensor 22a may be located between the upper hook 23 and the crane trolley, between the lower hook 21 and the connecting member 41, or between the end of the load chain Cl and the lower hook 21, etc.

[0042] The driver 29 adjusts the power supplied from a power source such as an external or built-in battery (not shown) to an appropriate level based on the current value of the drive motor 26, the output value of the encoder 26a, a command value for motor drive control given from the hoist control unit 20, and the like, and gives the adjusted power to the drive motor 26, thereby rotating the drive motor 26. Since the drive motor 26 is a servo motor, the driver 29 is a servo driver.

[0043] The driver 29 has at least a torque control mode and controls the drive motor 26 based on commands from the hoist control unit 20 .

[0044] The hoist control unit 20 calculates the load torque applied to the drive motor 26 via the load sheave 25 from the load detected by the load sensor 22a, and provides command values ​​for position, speed, torque, etc. to the driver 29. The hoist control unit 20 is a computer including, for example, a CPU (Central Processing Unit), memory 20a (RAM (Random Access Memory), ROM (Read Only Memory), internal storage, external storage device, etc.), and an input / output interface. The memory 20a stores a control program and various parameters for operation in torque control mode.

[0045] The hoist control unit 20 also has a load calculation unit 20b and a float calculation unit 20c as a motor control unit. The load calculation unit 20b and the float calculation unit 20c are functionally realized by reading the above-mentioned control program and various parameters from the memory 20a and performing calculations with the CPU.

[0046] The load calculation unit 20b calculates the load torque applied to the drive motor 26 from the load chain Cl via the load sheave 25 based on the load detected by the load sensor 22a.

[0047] The float calculation unit 20c calculates a torque command value Tm when the operating mode is float mode. The torque command value Tm is calculated based on a reference load and a measured load, and is output to the driver 29. The reference load is set as a set load Wl0 at the start of float mode, and the measured load Wl is calculated by the load calculation unit 20b as needed.

[0048] [Control Configuration of Transport System] Next, the control configuration of the transport system 10 will be described with reference to Fig. 3. Fig. 3 is a configuration diagram showing the control configuration of the transport system 10 according to this embodiment.

[0049] The conveying system 10 includes, as control units, a conveying control unit 5, a hoisting machine control unit 20, and a robot control unit 30.

[0050] The hoisting machine control unit 20 has already been described above, but the transport control unit 5 and the robot control unit 30 are computers or integrated circuits that include, for example, a CPU (Central Processing Unit), memory (RAM (Random Access Memory), ROM (Read Only Memory), internal storage, external storage device, etc.), input / output interfaces, etc. The operator switch 51 is a switch that is provided on a transport work panel arranged near the transport system 10 and is operated by an operator.

[0051] The transfer control unit 5 performs overall control of the transfer system 10. The transfer control unit 5 transmits signals related to control commands to the hoist control unit 20 and the robot control unit 30.

[0052] As described above, the hoisting machine control unit 20 sends a torque command to the driver 29 to operate the drive motor 26 based on commands sent from the conveying control unit 5, signals indicating the status of the robot control unit 30, and information such as the load sent from the load sensor 22a, thereby hoisting up and down the hoisting device 4 suspended from the hoisting machine 2.

[0053] Based on the control signal sent from the transport control unit 5, the robot control unit 30 sends a control signal to the drivers 30a to 30d of each part having the motors 31a to 34a so that the motors 31a to 34a can be controlled in a coordinated manner so that the robot device 3 moves as desired.

[0054] The operator switch 51 is a switch operated by an operator to transmit a control signal to the transport control unit 5, which indicates that the transport system 10 is to be activated or stopped.

[0055] [Control of Hoist] Next, an explanation will be given of the operation mode performed by the hoist control unit 20 when the workpiece Wo is transported by the transport system 10. Fig. 4 is a flowchart showing the setting of the set load Wl0 in the float mode of the hoist 2. The hoist control unit 20 of the hoist 2 calculates the torque command value Tm based on the set load and operates in the float mode.

[0056] In step S1, the hoist control unit 20 determines whether the hoist 2, which moves along the rails of the crane 1, is located above the suction position of the workpiece Wo based on a signal from the transport control unit 5. If the hoist 2 is not located above the suction position, the process proceeds to step S2, and if it is located above the suction position, the process proceeds to step S3.

[0057] As will be described later, when the workpiece Wo is transported by the transport system 10, the hoist 2 is set to the float mode or the descending float mode as torque control. The difference between the float mode and the descending float mode will be described with reference to the control flow in FIG.

[0058] In the following, when processing proceeds to step S2, it is referred to as "normal float mode," and when processing proceeds to step S3, it is referred to as "descent float mode." Normal float mode is an operating mode in which the workpiece Wo is wound up and wound down depending on whether or not an external force is applied, and the workpiece Wo is maintained in a suspended state unless an external force is applied. Descending float mode is an operating mode in which the workpiece Wo slowly descends without the application of an external force. Hereinafter, unless otherwise specified, the term "float mode" is a general term that includes both "normal float mode" and "descent float mode."

[0059] In step S2, the hoist control unit 20 sets the set load W10 based on the following (Equation 1): This step is executed in the normal float mode.

[0060] Set load Wl0 = Measured load Wl (Equation 1-1) The measured load Wl is the load value measured by the load sensor 22a minus the weight of the main body, etc., and is the load that attempts to rotate the load sheave 25 in the lowering direction, and is calculated by the load calculation unit 20b in the hoisting machine control unit 20.

[0061] Furthermore, when the robot device 3 is attached to the hoisting tool 4 or the workpiece Wo in a state where it cannot move relative to the robot device 3, the load value measured by the load sensor 22a may differ from the accurate weight of the hoisting tool 4 and / or the workpiece Wo because part of the weight of the hoisting tool 4 or the workpiece Wo may be added to the robot device 3. Here, the robot device 3 is set to a tracking control mode.

[0062] Therefore, in order to set the weight of the lifting device 4 and / or the workpiece Wo more accurately, the set load Wl0 may be calculated based on the above (Equation 1-1) taking into account the support load applied to the robot device 3, and on the basis of the following: Set load Wl0 = Measured load Wl + Robot device support load W2 (Equation 1-2).

[0063] Here, the robot device support load W2 is the measured value of the load applied to the load holding portion of the robot device 3's hoisting device 4 or the workpiece Wo, or a load that has been set in advance to control the robot device 3 so that the load holding portion of the robot device 3 holds the hoisting device 4 or the workpiece Wo at a predetermined support load.

[0064] In this embodiment, when the hoisting device 4 is moved horizontally, held, or lowered toward the workpiece Wo, the weight of the hoisting device 4 is known in advance and is stored in memory 20a, and the weight of the hoisting device 4 can be used as the measured load Wl.

[0065] The set load WlO is a reference load used in float mode control, and is calculated and stored in memory 20a as a measured load Wl when the float mode is started. Instead of the set load WlO stored in memory 20a, a reference torque TmO calculated by the following equation (3) may be stored.

[0066] In step S3, the hoist control unit 20 sets the set load W10 based on the following (Equation 2): This step is executed in the descending float mode.

[0067] Set load Wl0 = Measured load Wl - Pressing load α (Equation 2) The pressing load α is set so that the set load Wl0 that is balanced in float mode is intentionally made small to make the torque of drive motor 26 necessary to support the suspending device 4 insufficient, thereby lowering the suspending device 4. For example, the pressing load α is set to about 1 kg when the weight of the suspending device 4 is 20 kg, and is stored in advance in memory 20 a.

[0068] Note that the pressure load α is not limited to the above value, and may be any other value as long as it causes the suspender 4 to descend appropriately. From the above, the set load W10 will differ depending on whether step S2 or step S3 is performed. Therefore, the values ​​calculated by the following equations will also differ depending on whether step S2 or step S3 is performed.

[0069] Here, we will explain the float mode executed by the hoist control unit 20. In the float mode, the torque command value Tm is calculated by the following (Equation 3), (Equation 4), and (Equation 5) based on the set load Wl0 and the operating force Ws described above.

[0070] Tm0=(1 / i)×r×Wl0 (Equation 3) Th=(1 / i)×r×Ws (Equation 4) Tm=Tm0+Kl×Th (Equation 5) Note that i is the reduction ratio of speed reduction mechanism 27, r is the operating radius of load sheave 25, and Kl is the gain. In this embodiment, the worker does not operate the hoisting device 4, and therefore the operating force Ws is a force applied from the robot device 3. When an external force is applied from the robot device 3 in the vertical direction of the hoisting device 4, the external force is calculated as the operating force Ws.

[0071] That is, the hoist control unit 20 calculates the reference torque Tm0, which is the torque of the drive motor 26 corresponding to the set load Wl0, using (Equation 3).

[0072] Next, the increase / decrease motor torque Th corresponding to the operating force Ws is calculated using (Equation 4). The operating force Ws is calculated using the following (Equation 6).

[0073] Ws = Wl0 - Wl (Equation 6) Note that, although the increase / decrease motor torque Th is calculated from the operating force Ws, it may also be calculated from the load torque Tl corresponding to the measured load Wl. The measured load Wl calculated based on the load information output by the load sensor 22a can be converted into the load torque Tl applied to the load sheave 25 by the following (Equation 7).

[0074] Tl = (1 / i) x r x Wl (Equation 7) In other words, the hoisting machine control unit 20 performs torque control based on the reference torque Tm0 stored in the memory 20a and the load torque Tl measured and calculated in real time by the load sensor 22a.

[0075] Then, the torque command value Tm to be output to the drive motor 26 is calculated using (Equation 5) and is sent to the driver 29 .

[0076] Therefore, in both the normal float mode and the descending float mode, torque control is performed based on the reference torque Tm0 corresponding to the set load WlO set in step 2, step 3, and step 5 described later, and the increasing / decreasing motor torque Th corresponding to the operating force Ws calculated from the difference between the set load WlO and the measured load Wl that varies due to external forces. In other words, in the two float modes, different torque controls are performed based on the reference torque Tm0 calculated from the set load WlO and the load torque Tl calculated from the varying measured load Wl.

[0077] In step S4, the hoist control unit 20 determines whether or not the hoisting device 4 has completed suction of the workpiece Wo. If suction has been completed, the process proceeds to step S5, and if suction has not been completed, the process returns to step S1.

[0078] In step S5, the hoisting machine control unit 20 sets the set load Wl0 based on the following (Equation 8): This step is executed in the normal float mode when the hoisting device 4 has adsorbed the workpiece Wo.

[0079] Set load Wl0=hanging tool weight+workpiece weight (Equation 8) Note that, since the hanging tool weight and the workpiece weight are known, (Equation 8) is calculated using the hanging tool weight and the workpiece weight stored in advance in memory 20a.

[0080] The hoist control unit 20 notifies the transport control unit 5 that the setting of the set load Wl0 in step S5 has been completed. Upon receiving this notification, the robot control unit 30 determines that the hoisting tool 4 holding the workpiece Wo can now be transported, and starts the transport.

[0081] [Operation of the Transport System] (When Picking) Next, the operation of the transport system 10 will be described with reference to Figures 5 to 7. Figure 5 is an operation table showing the operation of each component of the transport system 10. Figures 6 and 7 are schematic diagrams showing the state of each component when the transport system 10 is picking.

[0082] 5 shows, from the left, the work step, the operating state of the transport system 10, the operating mode of the hoist 2, the set load W10 of the hoist 2, and the control state of the robot device 3. In FIG. 5, the above states are arranged in chronological order from the top, and the steps are shown switching at the timing of changes.

[0083] In step S11, the transport system 10 sets the hoisting machine 2 to normal float mode, the set load Wl0 of the hoisting machine 2 to the hoisting tool load (FIG. 4; S2), and the robot device 3 to position control. The transport system 10 moves the hoisting tool 4 of the hoisting machine 2 to above the suction position of the workpiece Wo. The hoisting machine 2 is freely movable horizontally by the traveling rails 11 and the traverse rails 12, and drives the motors 31a to 36a of the robot device 3 to move the hoisting tool 4 to the desired position via the connecting member 41.

[0084] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0085] In step S12, when the hoisting device 4 moves to directly above the suction position of the workpiece Wo, the conveying system 10 sets the hoisting machine 2 to descending float mode, the set load Wl0 of the hoisting machine 2 to [hoisting device load - pressing load α] (Figure 4; S3), and the robot device 3 to tracking control.

[0086] The term "profile control" used in this specification refers to a control method in which the robot device 3 is operated by feedback control, with the goal of maintaining a constant value for the force it receives from the hoisting device 4 at a certain position. Furthermore, during profile control, the force with which the robot device 3 holds the load of the hoisting device 4 can be made substantially zero.

[0087] As a result, as shown in Figure 7, the hoisting machine control unit 20 lowers the hoisting device 4 to the suction position of the workpiece Wo. At this time, the set load Wl0 of the hoisting machine 2 is [hoisting device load - pressing load α], which is set to be lighter than the actual weight of the hoisting device 4, so the hoisting device 4 is lowered by lowering the load chain Cl with a constant insufficient torque of the drive motor 26. In addition, because the robot is set to profile control, it follows the descent of the hoisting device 4 downward without resisting it.

[0088] In step S13, when the conveyance system 10 determines using the load sensor 22a or the like that the hoisting tool 4 has come into contact with the workpiece Wo, as shown in Fig. 7, the conveyance system 10 uses the lifting magnet to attract the workpiece Wo. Note that the contact between the hoisting tool 4 and the workpiece Wo may be determined by calculating the load acting on the hand unit 37a from the detection value detected by the torque sensors 31b to 36b incorporated in the robot device 3, instead of the load sensor 22a.

[0089] When the hoisting device 4 is lowered and descended, if the robot device 3 is in position control and the operation mode of the hoisting machine 2 is in normal float mode, or if the robot device 3 is in profile control and the hoisting machine 2 is in position control, a deviation in the control position in the height direction during position control may cause the hoisting device 4 to be lowered too much, even after it abuts the workpiece Wo, causing deflection in the load chain Cl. Furthermore, if the height is controlled so that the hoisting device 4 is in a position above where it abuts the workpiece Wo, a gap may form between the hoisting device 4 and the workpiece Wo.

[0090] In this step S13, the robot device 3 or the hoisting machine 2 is not position-controlled, and the set load Wl0 of the hoisting machine 2 is set in step S12 to be lighter than the set load Wl0 corresponding to the actual weight of the lifting device 4. As a result, the torque of the drive motor 26 becomes smaller than in normal float mode, and the lifting device 4 descends slowly due to gravity until it is reliably landed on the workpiece Wo (Figure 7).

[0091] The tracking control of the robot device 3 in steps S12 and S13 can be set as appropriate, such as three-axis tracking control or tracking control in only the Z-axis direction. However, when suctioning the workpiece Wo, three-axis tracking control can mitigate the impact on the robot.

[0092] In step S14, the transport system 10 sets the hoisting machine 2 to normal float mode, the set load W10 of the hoisting machine 2 to [work load + hoisting tool load] (FIG. 4; S5), and the robot device 3 to position control.

[0093] As a result, the conveying system 10 conveys the hoisting tool 4 suspending the workpiece Wo to the release position of the workpiece Wo. The workpiece Wo and the hoisting tool 4 are moved up and down by the robot device 3 or the hoisting machine 2, and are moved horizontally by the robot device 3.

[0094] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0095] (Dropping) In steps S11 to S14 above, the operation of lowering the hoisting tool 4, suctioning the workpiece Wo to the hoisting tool 4, and transporting it toward the release position has been described. In subsequent steps S15 to S18, the operation of transporting the workpiece Wo above the release position and then releasing it at the release position (dropping) will be described.

[0096] When picking, the hoisting tool 4 is lowered to adsorb the workpiece Wo, but when dropping, the hoisting tool 4, which already has the workpiece Wo adsorbed, is lowered to release the workpiece Wo. The difference between picking and dropping is whether the workpiece Wo is adsorbed to the hoisting tool 4 that is being lowered. As shown in Figure 5, only the set load W10 of the hoisting machine 2 differs between picking and dropping, and the other operations are the same.

[0097] The operation of the transport system 10 when dropped will be described with reference to Figures 5, 8 and 9. Figures 8 and 9 are schematic diagrams showing the state of each component of the transport system 10 when dropped.

[0098] In step S15, the transport system 10 sets the hoisting machine 2 to normal float mode, the set load Wl0 of the hoisting machine 2 to [work load + hoisting tool load] ( FIG. 4 ; S5), and the robot device 3 to position control. The transport system 10 moves the hoisting tool 4 of the hoisting machine 2 to above the release position of the workpiece Wo. As in the case of picking, the hoisting machine 2 can move freely in the horizontal direction using the traveling rails 11 and the lateral rails 12, and drives each motor of the robot device 3 to move the hoisting tool 4 to the desired position via the connecting member 41.

[0099] Furthermore, with the robot device set to profile control, the set load W10 may be set to [work load + hoisting tool load + robot device support load] using a value calculated from the load detected by the load sensor 22a and torque sensors 31b to 36b to determine the load acting on the hand unit 37a. This allows the load to be set accurately even when the work load and hoisting tool load are unknown.

[0100] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0101] In step S16, when the hoisting device 4 moves to above the release position of the workpiece Wo, the conveying system 10 sets the hoisting machine 2 to descending float mode, the set load Wl0 of the hoisting machine 2 to [workpiece load + hoisting device load - pressing load α] (Figure 4; S3), and the robot device 3 to tracking control.

[0102] As a result, as shown in Figure 8, the transport system 10 uses the hoist 2 to lower the workpiece Wo to the release position. At this time, the set load Wl0 of the hoist 2 is [workpiece load + hoisting tool load - pressing load α], which is set to be lighter than the actual weight of the workpiece Wo and the hoist 4, so the workpiece Wo and the hoist 4 are lowered by the lowering of the load chain Cl with a constant insufficient torque of the drive motor 26. In addition, because the robot device 3 is set to profile control, it follows the descent of the workpiece Wo and the hoist 4 downward without resisting it.

[0103] In step S17, when the transport system 10 determines that the workpiece Wo has come into contact with the work surface by the robot device 3 or the hoist 2, as shown in Figure 9, it releases the suction part 42 and releases the workpiece Wo.

[0104] When the workpiece Wo is lowered and descended, if the robot device 3 is in position control and the operation mode of the hoisting machine 2 is in normal float mode, or if the robot device 3 is in profile control and the hoisting machine 2 is in position control, a deviation in the control position in the height direction during position control may cause the workpiece Wo to be lowered too much, even after it abuts the work surface, causing deflection in the load chain Cl. Also, if the height is controlled to a position higher than where the workpiece Wo abuts the work surface, a gap may occur between the workpiece Wo and the work surface.

[0105] In this step S17, the robot device 3 or the hoist 2 is not position-controlled, and the set load WlO of the hoist 2 is set in step S16 to be lighter than the set load WlO corresponding to the actual weight of the workpiece Wo and the lifting device 4. As a result, the torque of the drive motor 26 is smaller than in the normal float mode, and the workpiece Wo can be slowly and reliably placed on the work surface by gravity (Figure 9).

[0106] As in the case of picking, the tracking control of the robot device 3 in steps S16 and S17 can be set as appropriate, such as three-axis tracking control or tracking control in only the Z-axis direction. However, when releasing the workpiece Wo, three-axis tracking control can mitigate the impact on the robot.

[0107] In step S18, the transport system 10 sets the hoisting machine 2 to the normal float mode, the set load of the hoisting machine 2 to the lifting tool load (FIG. 4; S2), and the robot device 3 to position control.

[0108] As a result, the conveying system 10 conveys the hoisting tool 4 that is not suspending the workpiece Wo to the suction position of the next workpiece Wo. The vertical movement of the workpiece Wo and the hoisting tool 4 is mainly performed by the hoisting machine 2, and the horizontal movement is performed by the robot device 3.

[0109] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0110] Second Embodiment Next, a second embodiment will be described.

[0111] The transfer system 120 of this embodiment has the same basic configuration as that of the first embodiment, but the control content is different. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0112] [Operation of the Transport System] (When Picking) Next, the operation of the transport system 120 will be described with reference to Fig. 6, Fig. 7, and Fig. 10. Fig. 10 is an operation table showing the operation of each component of the transport system 120 in the second embodiment.

[0113] In step S21, the transport system 120 sets the hoisting machine 2 to normal float mode, the set load Wl0 of the hoisting machine 2 to the hoisting tool load (FIG. 4; S2), and the robot device 3 to position control. The transport system 120 moves the hoisting tool 4 of the hoisting machine 2 to above the suction position of the workpiece Wo. The hoisting machine 2 is freely movable in the horizontal direction by the traveling rails 11 and the lateral travel rails 12, and drives each motor of the robot device 3 to move the hoisting tool 4 to the desired position via the connecting member 41.

[0114] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0115] In step S22, when the lifting tool 4 moves above the suction position of the workpiece Wo, the transport system 120 torque-controls the robot device 3 downward with a load α while leaving the operation mode and set load WlO of the hoisting machine 2 unchanged (FIG. 4; S2). In other words, the robot device 3 applies a holding force of −α.

[0116] As a result, as shown in Fig. 6, the transport system 120 lowers the hoisting machine 2 to the suction position of the workpiece Wo. At this time, the set load Wl0 of the hoisting machine 2 is the hoisting tool load, and if left as is, it would be stopped in the vertical direction, but the robot device 3 torque controls the hoisting tool 4 downward with a load α. Therefore, the hoisting machine 2 hoists the hoisting tool 4 downward as the hoisting tool 4 receives a downward external force by the amount of the load α.

[0117] The load α that the robot device 3 pushes downward is set to a light load that is sufficiently light compared to the load of the hoisting device 4, such as 1 kg when the hoisting device 4 weighs 20 kg, but any other load value may be used as long as it is a value that can ensure that the hoisting device 4 is securely attached to the workpiece Wo while preventing damage to the workpiece Wo.

[0118] In step S23, the conveyance system 120 determines, using the load sensor 22a and the like, that the hoisting tool 4 has come into contact with the workpiece Wo, as shown in FIG. 7, and then uses the suction unit 42 to suction the workpiece Wo. Note that the contact between the hoisting tool 4 and the workpiece Wo may be detected by the robot device 3 instead of the load sensor. In particular, in the second embodiment, the robot device 3 controls the torque of the hoisting tool 4 downward, and therefore detecting the reaction force caused by the hoisting tool 4 coming into contact with the workpiece Wo makes it possible to more reliably determine whether the hoisting tool 4 has landed on the workpiece Wo.

[0119] As a result, when the hoisting tool 4 is lowered and descended, after the hoisting tool 4 comes into contact with the workpiece Wo, the robot device 3 cannot lower the hoisting tool 4 any further, so that excessive lowering that causes deflection in the load chain Cl can be prevented, and a gap can be prevented from occurring between the hoisting tool 4 and the workpiece Wo.

[0120] In step S24, the transport system 120 maintains the hoisting machine 2 in normal float mode, sets the set load W10 of the hoisting machine 2 to [work load + lifting tool load] (FIG. 4; S5), and sets the robot device 3 to position control.

[0121] As a result, the transport system 120 transports the hoisting tool 4 suspending the workpiece Wo to the release position. The vertical movement of the workpiece Wo and the hoisting tool 4 is mainly performed by the hoisting machine 2, and the horizontal movement is performed by the robot device 3.

[0122] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0123] (Dropping) In steps S21 to S24 above, the operation of lowering the hoisting tool 4, suctioning the workpiece Wo to the hoisting tool 4, and transporting it toward the release position has been described. In the following steps S25 to S28, the operation of transporting the workpiece Wo above the release position and then releasing it at the release position will be described.

[0124] When picking, the hoisting tool 4 is lowered to adsorb the workpiece Wo, but when dropping, the hoisting tool 4, which already has the workpiece Wo adsorbed, is lowered to release the workpiece Wo. The difference between picking and dropping is whether the workpiece Wo is adsorbed to the hoisting tool 4 that is being lowered. As shown in Figure 10, only the set load W10 of the hoisting machine 2 differs between picking and dropping, and the other operations are the same.

[0125] The operation of the transport system 120 during dropping will be described with reference to FIGS.

[0126] In step S25, the transport system 120 sets the hoisting machine 2 to normal float mode, the set load Wl0 of the hoisting machine 2 to [work load + hoisting tool load] ( FIG. 4 ; S5), and the robot device 3 to position control. The transport system 120 moves the hoisting tool 4 of the hoisting machine 2 to above the release position of the workpiece Wo. As in the case of picking, the hoisting machine 2 can move freely in the horizontal direction using the traveling rails 11 and the lateral rails 12, and drives each motor of the robot device 3 to move the hoisting tool 4 to the desired position via the connecting member 41.

[0127] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0128] In step S26, when the hoisting device 4 moves to above the release position of the workpiece Wo, the transport system 120 sets the hoisting machine 2 in normal float mode, maintains the set load Wl0 of the hoisting machine 2 at [workpiece load + hoisting device load] (FIG. 4; S3), and sets the robot device 3 to downward torque control with a load α. In other words, the robot device 3 applies a holding force of −α.

[0129] As a result, the transport system 120 lowers the workpiece Wo to the release position, as shown in Figure 8. At this time, the set load Wl0 of the hoisting machine 2 is [workpiece load + hoisting tool load], and if left as is, it would be stopped in the vertical direction, but the robot device 3 torque controls the hoisting tool 4 downward with a load α. Therefore, the hoisting machine 2 hoists the hoisting tool 4 downward as the hoisting tool 4 receives a downward external force by the amount of load α.

[0130] The load α that the robot device 3 pushes downward is set to a light load, for example, 1 kg, which is sufficiently light compared to the load of the hoisting device 4 when the workpiece Wo weighs 100 kg and the hoisting device 4 weighs 20 kg, but any other load value may be used as long as it is a value that can securely place the workpiece Wo on the work surface while preventing damage to the workpiece Wo.

[0131] In step S27, when the transport system 120 determines that the workpiece Wo has contacted the work surface using the robot device 3, as shown in Fig. 9, it releases the lifting magnet to release the workpiece Wo. In particular, in the second embodiment, the robot device 3 controls the torque of the hoisting tool 4 downward, so that it is possible to more reliably determine whether the hoisting tool 4 has landed on the workpiece Wo by detecting the reaction force caused by the hoisting tool 4 contacting the workpiece Wo.

[0132] As a result, when the workpiece Wo is lowered and lowered, the robot device 3 cannot lower the lifting device 4 any further after the workpiece Wo comes into contact with the work surface, which prevents the load chain Cl from being lowered too much and causing sagging, and also prevents a gap from being created between the workpiece Wo and the work surface.

[0133] In step S28, the transport system 120 maintains the hoisting machine 2 in normal float mode, sets the set load W10 of the hoisting machine 2 to the lifting tool load (FIG. 4; S2), and sets the robot device 3 to position control.

[0134] As a result, the transport system 120 transports the hoisting tool 4 that is not suspending the workpiece Wo to the suction position of the next workpiece Wo. The vertical movement of the workpiece Wo and the hoisting tool 4 is mainly performed by the hoisting machine 2, and the horizontal movement is performed by the robot device 3.

[0135] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0136] Third Embodiment Next, a third embodiment will be described.

[0137] The transfer system 130 of this embodiment has the same basic configuration as that of the first embodiment, but the control content is different. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0138] [Operation of the Transport System] (When Picking) Next, the operation of the transport system 130 will be described with reference to Fig. 6, Fig. 7, and Fig. 11. Fig. 11 is an operation table showing the operation of each component of the transport system 130 in the third embodiment.

[0139] In step S31, the transport system 130 sets the hoisting machine 2 to normal float mode, the set load W10 of the hoisting machine 2 to [hoisting tool load - α] (FIG. 4; S3), and the robot device 3 to position control. At this time, the robot device 3 is controlled so that a supporting force of α is applied.

[0140] The set load Wl0 of the hoisting machine 2 is set by measuring the load of the hoisting device 4 with a load sensor of the hoisting machine 2. The load of the hoisting device 4 is measured in a state in which the robot device 3 applies a force in a direction to lift the hoisting device 4 upward by a predetermined load α. As a result, the load of the hoisting device 4 is detected as being lighter by the load α than the actual load, and the detected value becomes the set load Wl0 of the hoisting machine 2.

[0141] In addition to being set based on the detected value, the set load Wl0 may also be set based on the known weight of the lifting device 4, for example by torque controlling the robot device 3, and the load calculated from the control value that provides a predetermined holding force may be set as the set load Wl0.

[0142] The transport system 130 moves the hoisting device 4 of the hoisting machine 2 to above the suction position of the workpiece Wo. The hoisting machine 2 is freely movable in the horizontal direction by the running rails 11 and the lateral rails 12, and drives each motor of the robot device 3 to move the hoisting device 4 to the desired position via the connecting member 41.

[0143] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0144] In step S32, when the lifting device 4 moves to above the suction position of the workpiece Wo, the transport system 130 maintains the operating mode of the hoisting machine 2, the set load W10 (FIG. 4; S3), and the control state of the robot device 3 as they are.

[0145] 6, the transport system 130 lowers the hoisting machine 2 to the suction position of the workpiece Wo. At this time, the set load Wl0 of the hoisting machine 2 is [hoisting tool load - α], and the hoisting tool 4 is lowered in a state in which the robot device 3 constantly applies a force in a direction lifting the hoisting tool 4 upward by the load α.

[0146] In step S33, when the conveying system 130 detects that the load α supported by the robot device 3 has become zero, it determines that the lifting device 4 has landed in close contact with the workpiece Wo, and switches the robot device 3 to tracking control.

[0147] If the robot device 3 is to be controlled in position control mode at this time, it is preferable to set the target position below the workpiece Wo to ensure that the hoisting tool 4 is in close contact with the workpiece Wo. Furthermore, if the load α supported by the robot device 3 does not become zero even after the target position has been reached, the target position may be reset further downward. When the robot device 3 operates in position control and the hoisting tool 4 lands on the workpiece Wo, the robot device 3 may be switched to profile control and the hoisting tool 2 may be landed in the descending float mode to avoid impact at the time of landing.

[0148] By controlling in the above manner, when the hoisting device 4 is lowered and descended, after the hoisting device 4 comes into contact with the workpiece Wo, the robot device 3 cannot lower the hoisting device 4 any further, thereby preventing excessive lowering that causes deflection in the load chain Cl, and also preventing insufficient lowering that causes a gap to form between the hoisting device 4 and the workpiece Wo.

[0149] In step S34, the transport system 130 maintains the hoisting machine 2 in normal float mode, sets the set load W10 of the hoisting machine 2 to [work load + lifting tool load - α], and sets the robot device 3 to position control.

[0150] As a result, the transport system 130 transports the hoisting tool 4 suspending the workpiece Wo to the release position. The vertical movement of the workpiece Wo and the hoisting tool 4 is mainly performed by the hoisting machine 2, and the horizontal movement is performed by the robot device 3. Even in this state, the robot device 3 is always applying an upward force of the load α to the hoisting tool 4.

[0151] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0152] (Dropping) In steps S31 to S34 above, the operation of lowering the hoisting tool 4, suctioning the workpiece Wo to the hoisting tool 4, and transporting it toward the release position has been described. In subsequent steps S35 to S38, the operation of transporting the workpiece Wo above the release position and then releasing it at the release position will be described.

[0153] When picking, the hoisting tool 4 is lowered to adsorb the workpiece Wo, but when dropping, the hoisting tool 4, which already has the workpiece Wo adsorbed, is lowered to release the workpiece Wo. The difference between picking and dropping is whether the workpiece Wo is adsorbed to the hoisting tool 4 that is being lowered. As shown in Figure 11, only the set load W10 of the hoisting machine 2 differs between picking and dropping, and the other operations are the same.

[0154] The operation of the transport system 130 during dropping will be described with reference to FIGS.

[0155] In step S35, the transport system 130 sets the hoisting machine 2 to normal float mode, the set load Wl0 of the hoisting machine 2 to [work load + hoisting tool load - α], and the robot device 3 to position control. The transport system 130 moves the hoisting tool 4 of the hoisting machine 2 to above the release position of the workpiece Wo. As in the case of picking, the hoisting machine 2 can move freely in the horizontal direction using the traveling rails 11 and the lateral rails 12, and drives each motor of the robot device 3 to move the hoisting tool 4 to the desired position via the connecting member 41.

[0156] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0157] In step S36, when the lifting device 4 moves to above the release position of the workpiece Wo, the conveying system 130 maintains the hoisting machine 2 in normal float mode, the set load Wl0 of the hoisting machine 2 at [workpiece load + lifting device load - α], and the robot device 3 in position control.

[0158] As a result, the transport system 130 lowers the workpiece Wo to the release position, as shown in Figure 8. At this time, the set load Wl0 of the hoisting machine 2 is [workpiece load + hoisting tool load - α], which is set to be lighter than the actual weight of the hoisting tool 4. In other words, the load α is always supported by the robot device 3. Because the robot device 3 is position-controlled, when the robot device 3 descends, the workpiece Wo and the hoisting tool 4 follow and descend.

[0159] The load α that the robot device 3 always supports is set to a light load, for example, 1 kg when the workpiece Wo is 100 kg and the hoisting device 4 is 20 kg, which is sufficiently light compared to the load of the hoisting device 4, but other load values ​​may be used as long as they are sufficient to prevent damage to the workpiece Wo while ensuring that the workpiece Wo is securely placed on the work surface.

[0160] In step S37, the transport system 130 switches the robot device 3 to profile control. When it detects that the load α supported by the robot device 3 has become zero, it determines that the workpiece Wo has landed on the work surface.

[0161] If the robot device 3 is to be controlled in position control mode at this time, it is preferable to set the target position below the work surface to ensure that the workpiece Wo lands on the ground. Also, if the load α supported by the robot device 3 does not become zero even after the target position has been reached, the target position may be reset further downward. When the robot device 3 operates in position control and the workpiece Wo lands on the work surface, the robot device 3 may be switched to profile control and the hoist 2 may be used in a descending float mode to land the workpiece Wo on the ground to avoid impact at the time of landing.

[0162] By controlling in the above manner, when the workpiece Wo is lowered and descended, after the workpiece Wo comes into contact with the work surface, the robot device 3 cannot lower the workpiece Wo any further, thereby preventing the load chain Cl from being lowered too much and causing sagging, and also preventing a gap from being created between the lifting device 4 and the workpiece Wo due to insufficient lowering.

[0163] In addition, in step S38, the transport system 130 maintains the hoisting machine 2 in normal float mode, sets the set load W10 of the hoisting machine 2 to [hoisting tool load - α], and sets the robot device 3 to position control.

[0164] As a result, the transport system 130 transports the hoisting tool 4 that is not suspending a workpiece Wo to the suction position for the next workpiece Wo. The vertical movement of the workpiece Wo and the hoisting tool 4 is mainly performed by the hoisting machine 2, and the horizontal movement is performed by the robot device 3. Even in this state, the robot device 3 is always applying an upward force of the load α to the hoisting tool 4.

[0165] At this time, the robot device 3 moves the hand unit 37a to the coordinates determined by the position control. Since the hoisting machine 2 is normally set to the float mode, it follows the up and down movement of the robot device 3 and performs hoisting and lowering so as to minimize the load on the robot device 3.

[0166] [Modification] In the above embodiment, the robot device 3 is fixed to the work ground, but it may be mounted on the crane 1 or a cart that can move horizontally on the floor surface.

[0167] In each of the above embodiments, when setting the set load Wl0 of the hoisting machine 2, load measurement of the lifting device 4 and the workpiece Wo is omitted as they are known, but if they are not known, the set load Wl0 can be set based on the value obtained by performing load measurement.

[0168] Furthermore, in the first embodiment described above, when the lifting device 4 is adsorbed to the workpiece Wo, it remains in the descending float mode, but if it is anticipated that the load may collapse, the float mode may be stopped before the adsorption operation is performed.

[0169] In addition, in the above embodiment, the robot device 3 is configured with three joints 32, 33, and 34 and three arms 35, 36, and 37, but this is not limited to the above, and the numbers of the joints 32, 33, and 34 and the arms 35, 36, and 37 may be set appropriately depending on the usage environment.

[0170] In addition, in the above embodiment, a winding mechanism consisting of the load chain Cl as a hanging body and the load sheave 25 is used, but a winding mechanism consisting of a rope or belt and a winding drum (not shown) may also be used. In this case, the wound rope or belt is held by the winding drum, so the chain bucket 24 is not required.

[0171] Furthermore, in the above embodiment, the load sensor 22a is a load cell equipped with a strain gauge, but a crane scale or the like may also be used as long as it has the accuracy and responsiveness that can be used for torque control.

[0172] Furthermore, the drive motor 26 in the above embodiment may be a combination of an induction motor, an encoder, and a vector control type inverter control device, or may have some other configuration, as long as it is capable of at least torque control.

[0173] Furthermore, in the above embodiment, the pressure load α is set to approximately 1 kg when the weight of the sling 4 is 20 kg, but the pressure load α is not limited to the above value and may be any other value as long as it is a load that causes the sling 4 to descend appropriately.

[0174] In addition, in the above embodiment, the suction portion 42 is provided to adsorb the workpiece Wo using the lifting device 4, but the suction portion 42 may be any material that can reliably adsorb the workpiece Wo, such as a lifting magnet or a vacuum pad.

[0175] Furthermore, in the above embodiment, the pressing load α is set to approximately 1 kg when the weight of the hoisting tool 4 is 20 kg and the weight of the workpiece Wo is 100 kg, but if the weight of the workpiece Wo is lighter than the weight of the hoisting tool, such as when the weight of the hoisting tool 4 is 100 kg and the weight of the workpiece Wo is 10 kg, the pressing load α may be set to, for example, 10 kg, the weight of the workpiece Wo. As a result, when the workpiece Wo is released, the hoisting tool 4 does not rise or fall even in float mode without changing the set load of the hoisting machine 2, and can be maintained at a predetermined height without placing a load on the robot device 3.

[0176] Furthermore, in the above embodiment, the pressure load α is always set to a constant value when the hoist 4 and workpiece Wo are lowered. However, if the workpiece Wo is large and needs to be placed at an angle, for example, the workpiece Wo must be further lowered after one end of the workpiece Wo has landed on the floor. Therefore, the pressure load α may be gradually changed after one end of the workpiece Wo has landed on the floor. For example, the pressure load α may be set to 20 kg from the start of descent until one end of the workpiece Wo has landed on the floor, and may be decreased by 1 kg per second from the end of the workpiece Wo having landed on the floor until the entire workpiece Wo has landed on the floor. This reduces the risk of impact on the workpiece Wo, even when placing a large workpiece Wo at an angle.

[0177] Furthermore, in the above embodiment, this is performed during lowering, but the pressing load α can be set in the upward direction by making the drive motor torque greater than the torque applied by the hoisting machine 2. This makes it possible to prevent the load chain Cl from being deflected due to excessive winding during winding, for example, even when fitting work from below is performed using the robot device 3.

[0178] [Supplementary Explanation of the Embodiments] The above-described embodiments each show a preferred specific example of the present invention. The numerical values, components, arrangement positions of the components, order of connection, etc. shown in the above-described embodiments are merely examples and are not intended to limit the present invention. Furthermore, the drawings are not necessarily strict illustrations.

[0179] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0180] The above-described series of processes can be executed by hardware or software. When the series of processes are executed by software, the programs constituting the software are installed from a program recording medium into a computer incorporated in dedicated hardware, or into, for example, a general-purpose computer that can execute various functions by installing various programs.

[0181] The program executed by the computer may be a program that processes in chronological order according to the order described in this specification, or may be a program that processes in parallel or at the required timing, such as when called.

[0182] [Additional Notes] The contents of the above-described embodiments can be understood, for example, as follows.

[0183] (1) The pick transport system 10 includes a hoist 2 that lifts and lowers a hanging body Cl to lift and lower a workpiece Wo, a hoisting device 4 that is connected to the lower end of the hanging body Cl by a connecting member 41 and suspends the workpiece Wo, a robot device 3 that is connected to the hoisting device 4 and moves the hoisting device 4, and a crane 1 that moves the hoist 2 to follow and position itself directly above the hoisting device 4 as the robot device 3 moves the hoisting device 4. The hoist 2 is disposed on the hoisting device body and includes a load sheave 25 that lifts and lowers the hanging body Cl, a drive motor 26 that generates a driving force to rotate the load sheave 25, and a load torque calculator 27 that calculates the load torque applied to the load sheave 25. and a float calculation unit 20c that controls the torque of the drive motor 26 in a torque control mode that performs torque control based on the load torque. The torque control modes include a first torque control mode that controls the torque of the drive motor 26 so that a predetermined reference torque is balanced with a load obtained by subtracting the upward holding force of the robot device 3 from the weight of the hoisting device 4, and a second torque control mode that controls the torque of the drive motor 26 so that the torque is smaller by a predetermined value than the torque in the first torque control mode. The float calculation unit 20c selects the second torque control mode when lowering the hoisting device 4 toward the workpiece Wo.

[0184] As a result, when the float calculation unit 20c lowers the hoisting tool 4 toward the workpiece Wo, the second torque control mode is selected, and the torque of the drive motor 26 becomes smaller than the torque that balances with the predetermined reference torque. Therefore, even in the float mode, the hoisting tool 4 is lowered without applying an external force or by applying an external force downward.

[0185] Therefore, when the hoisting tool 4 descends and lands on the workpiece Wo, no gap is created between the hoisting tool 4 and the workpiece Wo, allowing for more reliable landing. Furthermore, because the hoisting machine 2 is in float mode, the descent of the hoisting tool 4 can be stopped immediately once the hoisting tool 4 lands on the workpiece Wo, preventing deflection of the hanging body Cl suspending the hoisting tool 4. Therefore, by lowering the hoisting tool 4 to an appropriate height, it is possible to prevent overload on the robot device 3.

[0186] (2) Control (Pick) When the lifting device 4 is lowered toward the workpiece Wo, the robot device 3 moves to follow the lifting device 4 using tracking control, and the float calculation unit 20c may control the torque of the drive motor 26 so that it is smaller than the load torque due to the weight of the lifting device 4.

[0187] As a result, the drive motor 26 of the hoisting machine 2 is controlled based on a torque smaller than the load torque due to the actual weight of the hoisting tool 4, and the robot device 3 follows the hoisting tool 4 by tracking control, so that the hoisting tool 4 gradually descends. Therefore, when the hoisting tool 4 contacts the workpiece Wo, it does so with a certain degree of momentum, so that the hoisting tool 4 can be more reliably landed on the floor without creating a gap between the hoisting tool 4 and the workpiece Wo.

[0188] (3) Robot Push (Pick) When the robot device 3 lowers the hoisting tool 4 toward the workpiece Wo, the robot device 3 may press the hoisting tool 4 downward.

[0189] As a result, while the hoisting machine 2 is suspending the hoisting tool 4 in float mode, the robot device 3 transports the hoisting tool 4 downward, so the robot device 3 can detect when the hoisting tool 4 has landed on the workpiece Wo. This allows the hoisting tool 4 to land on the workpiece Wo more reliably without creating a gap.

[0190] (4) Robot Lifting (Picking) When the lifting tool 4 is lowered toward the workpiece Wo, the reference torque may be set in advance in a state where the robot device 3 applies an upward holding force to the lifting tool 4 .

[0191] As a result, when measuring the load of the hoisting device 4 to set the set load Wl0 of the hoisting machine 2, the load of the hoisting device 4 is underestimated by the amount of upward holding force applied to the hoisting device 4 by the robot device 3, and the set load Wl0 is set based on that load.

[0192] Therefore, the hoisting machine 2 controls the drive torque of the drive motor 26 based on a load lighter than the actual load of the hoisting tool 4, and by using copy control over the robot device 3, the torque to support the hoisting tool 4 to prevent it from descending becomes insufficient, causing the hoisting tool 4 to gradually descend. In this state, the hoisting tool 4 abuts against the workpiece Wo with a certain amount of momentum, preventing any gap between the hoisting tool 4 and the workpiece Wo and allowing it to land more reliably.

[0193] (5) The drop transport system 10 includes a hoisting machine 2 that raises and lowers the hanging body Cl to raise and lower the workpiece Wo, a hoisting device 4 connected to the lower end of the hanging body Cl by a connecting member 41 and suspending the workpiece Wo, a robot device 3 connected to the hoisting device 4 or the workpiece Wo and moving the hoisting device 4 or the workpiece Wo, and a crane 1 that moves the hoisting machine 2 to follow the movement of the hoisting device 4 or the workpiece Wo by the robot device 3 so as to be positioned directly above the hoisting device 4 or the workpiece Wo, and the hoisting machine 2 is disposed on the hoisting machine body and includes a load sheave 25 that raises and lowers the hanging body Cl, a drive motor 26 that generates a driving force to rotate the load sheave 25, and a load torque applied to the load sheave 25. The robot device 3 is equipped with a load calculation unit 20b that calculates the torque of the drive motor 26, and a float calculation unit 20c that controls the torque of the drive motor 26 in a torque control mode that performs torque control based on the load torque. The torque control modes include a first torque control mode that controls the torque of the drive motor 26 so that a predetermined reference torque is balanced with the load obtained by subtracting the upward holding force of the robot device 3 from the sum of the weights of the hoisting device 4 and the workpiece Wo, and a second torque control mode that controls the torque of the drive motor 26 so that the torque is smaller by a predetermined value than the torque in the first torque control mode. The float calculation unit 20c selects the second torque control mode when the hoisting device 4 suspending the workpiece Wo is lowered toward the release position.

[0194] As a result, when the float calculation unit 20c lowers the hoisting tool 4 suspending the workpiece Wo toward the release position, the second torque control mode is selected and the torque of the drive motor 26 becomes smaller than the torque that balances the predetermined reference torque. Therefore, even in float mode, the hoisting tool 4 suspending the workpiece Wo is lowered without applying an external force or by applying an external force downward.

[0195] Therefore, when the hoisting tool 4 suspending the workpiece Wo descends and lands at the release position, no gap is created between the workpiece Wo and the work surface, allowing the workpiece Wo to land more reliably. Furthermore, because the hoisting machine 2 is in float mode, the descent of the hoisting tool 4 can be stopped immediately once the workpiece Wo lands on the work surface, preventing deflection of the hanging body Cl suspending the hoisting tool 4. Therefore, by lowering the hoisting tool 4 suspending the workpiece to an appropriate height, it is possible to prevent overloading of the robot device 3.

[0196] (6) Control (Drop) When the hoisting device 4 suspending the workpiece Wo is lowered toward the release position, the robot device 3 moves to follow the hoisting device 4 using tracking control, and the float calculation unit 20c may control the torque of the drive motor 26 so that it is smaller than the load torque due to the sum of the weights of the workpiece Wo and the hoisting device 4.

[0197] As a result, the drive motor 26 of the hoisting machine 2 is controlled based on a torque smaller than the load torque due to the actual weight of the workpiece Wo and the hoisting tool 4, and the robot device 3 follows the hoisting tool 4 by tracking control, so that the workpiece Wo and the hoisting tool 4 gradually descend. Therefore, when the hoisting tool 4 suspending the workpiece Wo abuts the release position, it does so with a certain degree of momentum, so that no gap is created between the hoisting tool 4 suspending the workpiece Wo and the work ground, and the hoisting tool 4 can be more reliably landed.

[0198] (7) Robot Push (Drop) When the robot device 3 lowers the hoisting tool 4 suspending the workpiece Wo toward the release position, the robot device 3 may press the hoisting tool 4 suspending the workpiece Wo downward.

[0199] As a result, while the hoist 2 is suspending the workpiece Wo and the hoisting tool 4 in float mode, the robot device 3 transports the workpiece Wo and the hoisting tool 4 downward, so the robot device 3 can detect when the workpiece Wo and the hoisting tool 4 have landed on the work surface. This allows the workpiece Wo to be more reliably landed on the work surface without any gaps.

[0200] (8) Robot lifting (dropping) When the hoisting device 4 suspending the workpiece Wo is lowered toward the release position, the reference torque may be set in advance in a state where an upward holding force is applied by the robot device 3 to the hoisting device 4 suspending the workpiece Wo.

[0201] As a result, when measuring the load of the workpiece Wo and the lifting device 4 to set the set load Wl0 of the hoisting machine 2, the load of the workpiece Wo and the lifting device 4 is underestimated by the amount of upward holding force applied to the workpiece Wo and the lifting device 4 by the robot device 3, and the set load Wl0 is set based on this load.

[0202] Therefore, the hoist 2 controls the drive torque of the drive motor 26 based on a load lighter than the actual load of the workpiece Wo and the hoisting tool 4, and by using profile control for the robot device 3, the torque to support the workpiece Wo and the hoisting tool 4 to prevent them from descending becomes insufficient, causing the workpiece Wo and the hoisting tool 4 to gradually descend. In this state, the workpiece Wo comes into contact with the work surface with a certain amount of momentum, preventing any gaps from forming between the workpiece Wo and the work surface and allowing it to land more reliably.

[0203] (9) Reference Torque Setting Method The transport system 10 includes a hoisting machine 2 that lifts and lowers a hanging body Cl to lift and lower a workpiece Wo, a hoisting tool 4 that is connected to the lower end of the hanging body Cl by a connecting member 41 and suspends the workpiece Wo, a robot device 3 that is connected to the hoisting tool 4 and moves the workpiece Wo, and a crane 1 that moves the hoisting machine 2 to follow the movement of the hoisting tool 4 by the robot device 3 so that the hoisting machine 2 is positioned directly above the hoisting tool 4, and the hoisting machine 2 is disposed on the hoisting machine main body and is connected to a load sheave that lifts and lowers the hanging body Cl. 25, a drive motor 26 that generates a driving force to rotate the load sheave 25, a load calculation unit 20b that calculates the load torque applied to the load sheave 25, and a float calculation unit 20c that controls the torque of the drive motor 26 in a torque control mode that performs torque control based on the load torque, and the torque control mode controls the torque of the drive motor 26 based on a predetermined reference torque and load torque, and the reference torque is set based on the load torque applied to the load sheave 25 and the torque applied to the robot device 3.

[0204] As a result, even if the weights of the hoisting device 4 and the workpiece Wo are unknown and cannot be set in advance, the weights of the hoisting device 4 and the workpiece Wo can be accurately calculated by measuring the set load Wl0 for the float mode of the hoisting machine 2 using the measured values ​​of the load sensor 22a and torque sensors 31b to 36b of the hoisting machine 2. Therefore, the hoisting device 4 or the workpiece Wo suspended from the hoisting device 4 can be lowered to an appropriate height with greater precision, and an overload on the robot device 3 can be prevented.

[0205] (10) Reference Torque (When Robot Intervenes) The robot device 3 may be controlled so that a predetermined torque is applied in advance, and the reference torque may be set based on the sum of the load torque applied to the load sheave 25 and the predetermined torque.

[0206] As a result, the weight of the lifting device 4 and the workpiece Wo can be accurately calculated using the load sensor 22a of the hoisting machine 2 and the known control value of the robot device 3, without measuring the load on the robot device 3. Therefore, since the process of measuring the load on the robot device 3 is not required, the picking operation and dropping operation can be performed more quickly.

[0207] (11) Reference Torque Setting Timing The reference torque may be set while the robot device 3 is in the profiling control mode.

[0208] This makes it possible to minimize the load on the robot device 3 when measuring the weight of the hoisting tool 4 and the workpiece Wo.

[0209] REFERENCE SIGNS LIST 1 Crane 2 Hoisting machine 3 Robot device 4 Lifting tool 10 Transport system 20b Load calculation unit 20c Float calculation unit (motor control unit) 22 Hoisting machine body 25 Load sheave (winding unit) 26 Drive motor 41 Connecting member 120 Transport system 130 Transport system Cl Load chain (hanging body) Wo Work

Claims

1. A transport system comprising: a hoisting machine that lifts and lowers a hanging body to raise and lower a workpiece; a hoisting device that is connected to the lower end of the hanging body by a connecting member and suspends the workpiece; a robot device that is connected to the hoisting device and moves the hoisting device; and a crane that moves the hoisting machine to follow and position itself directly above the hoisting device as the robot device moves the hoisting device, wherein the hoisting machine comprises: a winding unit that is disposed on a hoisting machine body and that hoists and lowers the hanging body; a drive motor that generates a drive force to rotate the winding unit; a load calculation unit that calculates a load torque applied to the winding unit; and a motor control unit that controls the torque of the drive motor in a torque control mode that controls torque based on the load torque, wherein the torque control mode comprises: a first torque control mode that controls the torque of the drive motor so that a predetermined reference torque is balanced with a load obtained by subtracting the upward holding force of the robot device from the weight of the hoisting device; a second torque control mode that controls the torque of the drive motor so that the torque is smaller than the torque in the first torque control mode by a predetermined value, wherein the motor control unit selects the second torque control mode when lowering the lifting tool toward the workpiece.

2. A conveying system as described in claim 1, characterized in that when the hoisting device is lowered toward the workpiece, the robot device moves to follow the hoisting device using tracking control, and the motor control unit controls the torque of the drive motor so that it is smaller than the load torque due to the weight of the hoisting device.

3. A conveying system according to claim 1, characterized in that the robot device presses the hoisting tool downward when lowering the hoisting tool toward the workpiece.

4. A conveying system as described in claim 1, characterized in that when the lifting device is lowered toward the workpiece, the reference torque is preset in a state in which the robot device applies an upward holding force to the lifting device.

5. A transport system comprising: a hoisting machine that raises and lowers a hanging body to raise and lower a workpiece; a hoisting device that is connected to the lower end of the hanging body by a connecting member and suspends the workpiece; a robot device that is connected to the hoisting device or the workpiece and moves the hoisting device or the workpiece; and a crane that moves the hoisting machine to follow and position itself directly above the hoisting device or the workpiece as the robot device moves the hoisting device or the workpiece, wherein the hoisting machine comprises: a winding unit that is disposed on a hoisting machine body and that hoists and lowers the hanging body; a drive motor that generates a drive force to rotate the winding unit; a load calculation unit that calculates the load torque applied to the winding unit; and a motor control unit that controls the torque of the drive motor in a torque control mode that controls torque based on the load torque, wherein the torque control mode is a first torque control mode that controls the torque of the drive motor so that a predetermined reference torque is balanced with a load obtained by subtracting the upward holding force of the robot device from the sum of the weights of the hoisting device and the workpiece; and a second torque control mode that controls the torque of the drive motor so that the torque is smaller by a predetermined value than the torque in the first torque control mode, wherein the motor control unit selects the second torque control mode when the hoisting device suspending the workpiece is lowered toward a release position.

6. A conveying system as described in claim 5, characterized in that when the hoisting device suspending the workpiece is lowered toward a release position, the robot device moves to follow the hoisting device using tracking control, and the motor control unit controls the torque of the drive motor so that it is smaller than the load torque due to the sum of the weights of the workpiece and the hoisting device.

7. A conveying system according to claim 5, characterized in that the robot device presses the hoisting tool suspending the workpiece downward when lowering the hoisting tool suspending the workpiece toward a release position.

8. A conveying system as described in claim 5, characterized in that when the hoisting device suspending the workpiece is lowered toward a release position, the reference torque is preset in a state in which an upward holding force is applied by the robot device to the hoisting device suspending the workpiece.

9. A transport system comprising: a hoist that raises and lowers a workpiece by hoisting up and down a hanging body; a hoisting device connected to the lower end of the hanging body by a connecting member and suspending the workpiece; a robot device connected to the hoisting device and moving the workpiece; and a crane that moves the hoisting machine to follow and position itself directly above the hoisting device as the robot device moves the hoisting device, wherein the hoisting machine comprises: a winding unit that is disposed on a hoisting machine body and hoists up and down the hanging body; a drive motor that generates a drive force to rotate the winding unit; a load calculation unit that calculates a load torque applied to the winding unit; and a motor control unit that controls the torque of the drive motor in a torque control mode that controls torque based on the load torque; wherein the torque control mode controls the torque of the drive motor based on a predetermined reference torque and the load torque, and the reference torque is set based on the load torque applied to the winding unit and the torque applied to the robot device.

10. A conveying system according to claim 9, characterized in that the robot device is controlled so that a predetermined torque is applied in advance, and the reference torque is set based on the sum of the load torque applied to the winding portion and the predetermined torque.

11. A transport system according to claim 9, wherein the reference torque is set when the robot device is in a tracking control mode.

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