Controller, actuator unit and robot

Abstract

To provide a technology capable of suppressing fluctuation of a rotation suppression degree of a driven device due to a transmission when a drive actuator is in an operation stop state.SOLUTION: A controller comprises an operation control unit 70 that controls the operation of a drive actuator 14 that comprises: a prime mover 22; a transmission 24 that changes the speed of rotation input from the prime mover 22 and outputs it to the driven device 12; and a speed change actuator 26 that can change an actual speed change ratio of the transmission 24. When the operation of the drive actuator 14 is to be stopped, the operation control unit 70 performs speed change ratio change control to change the actual speed change ratio to a preset set speed change ratio, by the speed change actuator 26.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a control device used for a drive actuator.

Background Art

[0002] Patent Document 1 discloses a drive actuator including a prime mover and a transmission that changes the rotation input from the prime mover and outputs it to a driven device. In the transmission of Patent Document 1, the gear ratio, which is the ratio of the rotational speed of the output shaft to the rotational speed of the input shaft, is a fixed ratio.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a transmission with a variable gear ratio is used, the gear ratio can vary in various ways during the operation of the drive actuator. Also, when the drive actuator is in an operation stop state where the operation is stopped, the degree to which the rotation of the driven device is suppressed by the transmission varies depending on the gear ratio of the transmission. For this reason, every time the operation of the drive actuator is stopped, there is a problem that the degree of rotation suppression of the driven device by the transmission fluctuates according to the gear ratio used immediately before the operation is stopped.

[0005] Therefore, one object of the present disclosure is to provide a technique capable of suppressing fluctuations in the degree of rotation suppression of a driven device by a transmission when the drive actuator is in an operation stop state.

Means for Solving the Problems

[0006] The control device of the present disclosure includes a prime mover, a transmission that changes the rotation input from the prime mover and outputs it to a driven device, and a shift actuator that can change the actual gear ratio of the transmission, and includes an operation control unit that controls the operation of the drive actuator. When the operation control unit attempts to stop the operation of the drive actuator, the shift actuator performs a gear ratio change control to change the actual gear ratio to a preset set gear ratio.

Advantages of the Invention

[0007] According to the present disclosure, when the drive actuator is in an operation stop state, fluctuations in the degree of rotation suppression of the driven device by the transmission can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the drive actuator of the present disclosure will be described. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, for the sake of convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the direction of the reference numerals.

[0010] (First Embodiment) Refer to FIG. 1. The actuator unit 10 is used to drive the driven device 12. The driven device 12 is, for example, a ball screw device used in a conveying device, a positioning device, or the like. The driven device 12 includes a rotation drive unit 12a that is rotationally driven by the actuator unit 10. The rotation drive unit 12a is, for example, a screw shaft used in a ball screw device. The specific example of the driven device 12 is not particularly limited, and it may be a part of industrial machinery (machine tools, construction machinery, etc.), robots (industrial robots, service robots, etc.), transportation equipment (conveyors, vehicles, etc.).

[0011] The actuator unit 10 includes a drive actuator 14 that drives the driven device 12, and a control device 16 that controls the operation of the drive actuator 14. The drive actuator 14 and the control device 16 operate using electric power supplied from an external main power source 18 or auxiliary power source 20. The main power source 18 is, for example, a commercial power source. The auxiliary power source 20 is, for example, an uninterruptible power supply (UPS), an output holding time extension module, or the like.

[0012] The drive actuator 14 includes a prime mover 22, a transmission 24 that changes the rotation input from the prime mover 22 and outputs it to the driven device 12, and a transmission actuator 26 that can change the transmission ratio of the transmission 24. Hereinafter, when referring to the rotation of the driven device 12 and the prime mover 22, it shall refer to the rotation of the entire rotating object in the object of reference. For example, when referring to the rotation of the driven device 12, it refers to the rotation of the entire object (such as the rotation drive unit 12a) rotating in the driven device 12, and when referring to the rotation of the prime mover 22, it refers to the rotation of the entire object (such as the prime mover shaft) rotating in the prime mover 22.

[0013] The prime mover 22 can rotate a prime mover shaft (not shown) by the torque generated inside itself, and then output the rotation from the prime mover shaft to the transmission 24. The prime mover 22 of the present embodiment is a motor (electric motor) that rotates the prime mover shaft using electrical energy. The motor can rotate the prime mover shaft by the torque generated by the cooperation of the stator and the rotor. A specific example of the prime mover 22 is not particularly limited, and for example, an engine that rotates the prime mover shaft using thermal energy may be used.

[0014] The transmission actuator 26 can change the transmission ratio of the transmission 24 by inputting power to the transmission 24. The transmission actuator 26 of the present embodiment is a linear actuator, and inputs power along the axial direction of the transmission 24 to the transmission 24. The specific type of the transmission actuator 26 is not particularly limited as long as it can change the transmission ratio of the transmission 24, and a rotary actuator or the like may be used.

[0015] Refer to FIG. 2. The transmission 24 includes an input shaft 40 to which rotation is input from the prime mover 22, a transmission mechanism 42 that transmits the rotation input to the input shaft 40 after changing the speed to an output shaft 44, an output shaft 44 that outputs the rotation transmitted from the transmission mechanism 42 to the driven device, and a transmission ratio changing mechanism 46 that changes the transmission ratio of the transmission mechanism 42.

[0016] The transmission 24 of this embodiment can continuously (steplessly) change the actual transmission ratio, which is the actual gear ratio, using the gear ratio change mechanism 46 by means of the shift actuator 26. The gear ratio here means the ratio of the output rotation speed, which is the rotation speed of the output shaft 44, to the input rotation speed, which is the rotation speed of the input shaft 40 (= output rotation speed / input rotation speed). The transmission 24 of this embodiment is an infinitely variable transmission (IVT), and is configured such that the variable range of the actual gear ratio includes zero (= 1 / ∞). Here, an example of such a transmission 24 will be described, but the specific example is not particularly limited. For example, the transmission 24 may be a toroidal continuously variable transmission or the like. Also, the transmission 24 may not include zero in the variable range. In this case, the continuously variable transmission may be, for example, a belt-type continuously variable transmission, a chain-type continuously variable transmission, or the like. Further, the transmission 24 may be a transmission capable of changing the gear ratio stepwise instead of a continuously variable transmission capable of continuously changing the gear ratio.

[0017] The input shaft 40 includes an input member 40a to which rotation is input from the prime mover 22, a shaft 40b connected to the input member 40a, and a sleeve 40c fixed to the shaft 40b. The specific structure of the input shaft 40 is not particularly limited as long as it can transmit rotation from the prime mover 22 to the transmission mechanism 42. The input shaft 40 here shows an example constituted by a plurality of members, but it may be constituted by a single member, and the number of its members is not particularly limited either.

[0018] The transmission mechanism 42 includes an input orbital gear 50 provided rotatably integrally with the input shaft 40, a first support orbital gear 52 rotatably supported by the input shaft 40, a second support orbital gear 56 provided movably in the axial direction within the casing 54 of the transmission 24, an output orbital gear 58 provided rotatably integrally with the output shaft 44, and a plurality of planetary rolling elements 60 that roll on the respective orbital gears 50, 52, 56, 58. The plurality of planetary rolling elements 60 are pressed against the output orbital gear 58 by a pressing force applied from the second support orbital gear 56 by a pressing force applying mechanism (not shown).

[0019] When the input orbital gear 50 rotates, the planetary rolling elements 60 revolve around the rotation axis L40 (revolution axis) of the input shaft 40 while rotating around their own rotation axis L60. When the planetary rolling elements 60 revolve, the output orbital gear 58 rotates around the rotation axis L40 following them. At this time, ideally, the output orbital gear 58 rotates at an output rotation speed obtained by multiplying the input rotation speed of the input shaft 40 by the speed ratio. This speed ratio is determined according to the inclination angle of the rotation axis L60 with respect to the rotation axis L40, and is changed by the speed ratio change mechanism 46.

[0020] The output shaft 44 includes an output orbital gear 58 and an output member 44a that is connected to the output orbital gear 58 for integral rotation and outputs rotation to the driven device 12. The specific structure of the output shaft 44 is not particularly limited as long as it can transmit rotation from the speed change mechanism 42 to the driven device 12. Here, the output shaft 44 shows an example constituted by a plurality of members, but it may be constituted by a single member, and the number of its members is not particularly limited either.

[0021] The speed ratio change mechanism 46 of the present embodiment can change the speed ratio by changing the position of the input orbital gear 50. The speed ratio change mechanism 46 includes a shaft 46a that can move axially by the power output from the speed change actuator 26, and a ring member 46b that can move axially integrally with the shaft 40b. The ring member 46b rotatably supports the input shaft 40 via a bearing 46c, and can move axially integrally with the input shaft 40 by a retaining ring or the like. The specific example of the speed ratio change mechanism 46 is not particularly limited, and various similar mechanisms adopted in the speed change machine 24 may be adopted.

[0022] When axial power is input from the transmission actuator 26 to the shaft 46a, the input shaft 40 (including the input orbital gear 50 and the first support orbital gear 52) moves axially integrally with the ring member 46b. When the input orbital gear 50 and the first support orbital gear 52 move axially with respect to the second support orbital gear 56 and the output orbital gear 58, the inclination angle of the rotation axis L60 of the rotation axis L40 of the planetary rolling element 60 is changed, and the transmission ratio is changed according to the inclination angle. This transmission ratio becomes zero (= 1 / ∞) when the rotation axis L60 is parallel to the rotation axis L40, and continuously increases as the inclination angle of the rotation axis L60 with respect to the rotation axis L40 increases. That is, the actual transmission ratio can be changed steplessly (continuously), and is configured to include zero in its variable range.

[0023] Returning to FIG. 1. The control device 16 is composed of a combination of hardware elements and software elements, or only hardware elements. As the hardware elements, for example, a processor, a ROM (Read Only Memory), and a RAM (Random Access Memory) are used. As the software elements, for example, programs such as an operating system and an application are used. The part used for controlling the prime mover 22 and the part used for controlling the transmission actuator 26 may be realized by a common hardware element or software element, or may be realized by separate hardware elements or software elements. The control device 16 is attached to the drive actuator 14 and can be handled integrally with the drive actuator 14.

[0024] The control device 16 includes an operation control unit 70 that controls the operation of the drive actuator 14, a setting unit 72 that variably sets a set transmission ratio (described later) used for the control by the operation control unit 70, and a storage unit 74 that stores data used for the control by the operation control unit 70. The operation control unit 70 can change the torque generated by the prime mover 22 by controlling the operation of the prime mover 22. The operation control unit 70 can change the transmission ratio of the transmission 24 by controlling the operation of the transmission actuator 26.

[0025] When the operation control unit 70 satisfies a predetermined operation stop condition (described later), it performs operation stop control to stop the operation of the drive actuator 14 by controlling the drive actuator 14. This operation stop control will be performed when attempting to stop the operation of the drive actuator 14. Here, "stopping the operation of the drive actuator 14" means stopping the operation of each power transmission element of the drive actuator 14. The power transmission elements here refer to the elements used for transmitting the torque (power) generated by the prime mover 22 to the driven device 12, such as the prime mover shaft of the prime mover 22, the input shaft 40 of the transmission 24, the transmission mechanism 42, the output shaft 44, and the like.

[0026] This operation stop control may be performed, for example, by the prime mover 22 generating a braking torque for braking each power transmission element of the drive actuator 14. In this case, when using an electric motor capable of generating a regenerative brake as the prime mover 22, regenerative energy may be generated while generating a braking torque by the prime mover 22. In addition to this, when the drive actuator 14 is equipped with a braking device, this operation stop control may be performed by the braking device generating a braking torque. In addition to this, this operation stop control may be performed by waiting until the operation of each power transmission element of the drive actuator 14 naturally stops without generating a braking torque by the prime mover 22 or the braking device.

[0027] When the operation control unit 70 attempts to stop the operation of the drive actuator 14 by this operation stop control, in the shift actuator 26, it performs shift ratio change control to change the actual shift ratio of the transmission 24 to a preset shift ratio. In this shift ratio change control, the operation control unit 70 changes the actual shift ratio to the preset shift ratio set by the setting unit 72. At this time, the operation control unit 70 reads out the preset shift ratio stored in the storage unit 74 by the setting unit 72, and changes the actual shift ratio to the read preset shift ratio.

[0028] During this gear ratio change control, the operation control unit 70 changes the actual gear ratio of the transmission 24 during the operation of the transmission 24, specifically, during the operation of at least the input shaft 40 of the transmission 24 and the transmission mechanism 42. After the change of the actual gear ratio of the transmission 24 by the gear ratio change control is completed, the operation of each power transmission element of the drive actuator 14 stops by the operation stop control. This is because the actual gear ratio of the transmission 24 cannot be smoothly changed by the transmission actuator 26 unless the input shaft 40 of the transmission 24 and the transmission mechanism 42 are operating. Thus, in order to perform the gear ratio change control while the transmission 24 is operating, the gear ratio change control may be performed while a rotation detector (not shown) detects that the input shaft 40 of the transmission 24 or the prime mover 22 is rotating.

[0029] When the operation of each power transmission element of the drive actuator 14 stops, that is, when the operation of the drive actuator 14 stops, the operation control unit 70 completes the operation stop control. The fact that the operation of the drive actuator 14 has stopped may be grasped by detecting the rotation stop of each power transmission element of the drive actuator 14 by a rotation detector (not shown). When the drive actuator 14 enters the operation stop state, the operation control unit 70 may stop the power supply to each electromechanical device (such as the prime mover 22 and the transmission actuator 26) used for the drive actuator 14. As a result, each electromechanical device enters a non-energized state where it is not energized.

[0030] When explaining the set transmission ratio set by the setting unit 72, the underlying concept will be explained. When the actual transmission ratio of the transmission 24 is zero or a value very close to zero, it enters a locked state (self-locking state) where the rotation of the output side (output shaft 44) of the transmission 24 is locked together with the driven device 12. This locked state means a state where it is difficult to rotate the transmission 24 from the output side, that is, a state where it is difficult to rotate the driven device 12 (the rotation drive unit 12a of the driven device 12). At this time, the input side (input shaft 40) of the transmission 24 can be rotated, but since the actual transmission ratio is very small, the output side of the transmission 24 can hardly or scarcely be rotated. In contrast, when the actual transmission ratio of the transmission 24 is set away from zero, a rotation-allowed state is established where the rotation of the output side of the transmission 24 is allowed together with the driven device 12.

[0031] The setting unit 72 variably sets the set transmission ratio used for the transmission ratio change control described above. The set transmission ratio will be set as a variable value that can be changed. When the setting unit 72 sets the set transmission ratio, it stores the set set transmission ratio in the storage unit 74. The setting unit 72 can set either the lock transmission ratio predetermined in advance as the transmission ratio of the transmission 24 for locking the rotation of the driven device 12 or the rotation-allowed transmission ratio predetermined in advance as the transmission ratio for allowing the rotation of the driven device 12 as the set transmission ratio. This lock transmission ratio refers to what is predetermined in advance as the transmission ratio for bringing the above-described locked state by locking the rotation of the driven device 12. Also, the rotation-allowed transmission ratio here refers to what is predetermined in advance as the transmission ratio for bringing the above-described rotation-allowed state by allowing the rotation of the driven device 12. For example, the lock transmission ratio is determined within a transmission ratio range from zero (= 1 / ∞) to 1 / thousands, and the rotation-allowed transmission ratio is determined within a transmission ratio range from 1 / 200 to 1 / dozens. Each of the transmission ratio ranges cited here is merely an example, and it may be set within other transmission ratio ranges.

[0032] The setting unit 72 may set a set gear ratio according to a command from a user or an external controller. Here, the external controller refers to, for example, a host controller that comprehensively controls the operations of a plurality of drive actuators 14. When setting the set gear ratio according to a designation from the user, the drive actuator 14 may include a first operation unit that outputs, as a command from the user, the designated gear ratio designated by the user through the user's operation to the control device 16. In this case, the setting unit 72 may set the designated gear ratio output from the first operation unit as the set gear ratio. The first operation unit is constituted by, for example, an information processing terminal such as a touch panel in addition to a switch provided on a control panel.

[0033] The setting unit 72 may continuously or stepwise change the set gear ratio within a rotation allowable gear ratio range predetermined as a gear ratio range for allowing the rotation of the driven device 12 described above. The setting unit 72 of the present embodiment can set the set gear ratio to the locked gear ratio and can set the set gear ratio to any one of a plurality of rotation allowable gear ratios. This rotation allowable gear ratio range may be, for example, the gear ratio range of 1 / 200 to 1 / several tens described above.

[0034] When the locked gear ratio is set as the set gear ratio by the setting unit 72, the operation control unit 70 changes the actual gear ratio of the transmission 24 to the locked gear ratio in the gear ratio change control. Thereby, when the drive actuator 14 is in the operation stop state, the rotation of the driven device 12 can be in a locked state where the rotation is locked. In this case, the operation control unit 70 may change the actual gear ratio of the transmission 24 from the locked gear ratio to the rotation allowable gear ratio by the transmission actuator 26 before starting the drive of the driven device 12 after starting the operation of the drive actuator 14.

[0035] When the rotation allowable gear ratio is set as the set gear ratio by the setting unit 72, the operation control unit 70 changes the actual gear ratio of the transmission 24 to the rotation allowable gear ratio in the gear ratio change control. Thereby, when the drive actuator 14 is in the operation stop state, the rotation of the driven device 12 can be in a rotation allowable state where the rotation is allowed.

[0036] The effects of the above control device 16 will be described. When the operation control unit 70 of the control device 16 attempts to stop the operation of the drive actuator 14, it performs a gear ratio change control to change the actual gear ratio of the transmission 24 to the set gear ratio by the shift actuator 26. Therefore, regardless of the actual gear ratio used immediately before stopping the operation of the drive actuator 14, the actual gear ratio when the drive actuator 14 is in the operation stop state can be set to the set gear ratio. For this reason, when the drive actuator 14 is in the operation stop state, fluctuations in the degree of rotation suppression of the driven device 12 by the transmission 24 can be suppressed.

[0037] Suppose a case where, when the drive actuator 14 is in the operation stop state, the power transmission element of the drive actuator 14 is braked by a non-excitation operation type brake in order to lock the rotation of the driven device 12. In this case, in order to release the braking by the non-excitation operation type brake, it is necessary to constantly supply power to the non-excitation operation type brake, resulting in problems such as an increase in energy consumption and heat generation. In this regard, the operation control unit 70 of the present embodiment can change the actual gear ratio of the transmission 24 to the lock gear ratio by the gear ratio change control. Therefore, when the drive actuator 14 is in the operation stop state, by changing the actual gear ratio of the transmission 24 to the lock gear ratio in advance by the gear ratio change control, the rotation of the driven device 12 can be locked by the transmission 24. Also, in order to release the lock by the transmission 24, it is only necessary to change the actual gear ratio of the transmission 24 by the shift actuator 26, and it is not necessary to constantly supply power as in the case of using a non-excitation operation type brake. Therefore, while advantageously solving the problem of an increase in energy consumption and heat generation, the rotation of the driven device 12 can be locked when in the operation stop state.

[0038] The control device 16 includes a setting unit 72 that variably sets a set gear ratio. Therefore, by changing the set gear ratio set by the setting unit 72, it becomes possible to adjust the degree of rotation suppression of the driven device 12 by the transmission 24 when the drive actuator 14 is in the operation stop state. Thereby, by adjusting the actual degree of rotation suppression according to the required degree of rotation suppression of the driven device 12, the flexibility of the operation of the drive actuator 14 can be enhanced.

[0039] The setting unit 72 can selectively set either a lock gear ratio for locking the rotation of the driven device 12 or a rotation allowable gear ratio for allowing the rotation as the set gear ratio. Therefore, by setting either the lock gear ratio or the rotation allowable gear ratio as the set gear ratio, when the drive actuator 14 is in the operation stop state, either a locked state or a rotation allowable state can be selected as the state of the driven device 12. Thereby, the flexibility of the operation of the drive actuator 14 can be further enhanced.

[0040] Conceivably, there is also a means of realizing it by changing the hardware in order to be able to select either a locked state or a rotation allowable state as the state of the driven device 12. Here, the change of the hardware means switching the presence or absence of the incorporation of the electromagnetic brake with respect to the drive actuator 14. In this regard, according to the present embodiment, there is an advantage that either a locked state or a rotation allowable state can be selected as the state of the driven device 12 only by changing the set gear ratio without accompanying a change in the hardware.

[0041] The setting unit 72 can change the set gear ratio stepwise or continuously within a rotation allowable gear ratio range that is predetermined as a gear ratio range in which the rotation of the driven device 12 is allowed. Thereby, when the drive actuator 14 is in the operation stop state, while allowing the rotation of the driven device 12, it becomes possible to adjust the degree of rotation suppression of the driven device by the transmission 24. As a result, the flexibility of the operation of the drive actuator can be further enhanced.

[0042] Next, the above-described operation stop conditions will be explained. The operation stop conditions are, for example, (1) receiving an operation stop command from the user or an external controller, (2) an abnormality occurring in the main power supply 18, etc.

[0043] When receiving an operation stop command from the user in (1), the drive actuator 14 may be provided with a second operation unit for outputting an operation stop command to the control device 16 according to the user's operation. This second operation unit may be constituted by, for example, an information processing terminal such as a touch panel in addition to a switch provided on the control panel. This switch may be a power switch for switching the presence or absence of power supply to the drive actuator 14. In this case, the second operation unit may output an operation stop command to the control device 16 by an off operation for stopping the power supply. When the condition in (1) is satisfied, when performing the above-described operation stop control and gear ratio change control, the operation control unit 70 may operate each electromechanical device (prime mover 22, transmission actuator 26, etc.) used for the drive actuator 14 using the power supplied from the main power supply 18. In addition to this, alternatively, the operation control unit 70 may operate each electromechanical device using the power supplied from the auxiliary power supply 20.

[0044] Explanation will be given for (2). An abnormality detector 80 for detecting an abnormality of the main power supply 18 is provided outside the drive actuator 14. When the abnormality detector 80 detects an abnormality of the main power supply 18, it outputs an abnormality detection signal indicating that fact to the control device 16. The abnormality here refers to an abnormality related to the power supply from the main power supply 18 to the drive actuator 14, such as a power failure of the main power supply 18, an abnormal voltage drop of the power supplied from the main power supply 18, an abnormal voltage rise, etc. The abnormality detector 80 may detect an abnormality of the main power supply 18 using various detection methods including known methods. For example, when the voltage value of the power supplied from the main power supply 18 becomes equal to or higher than a predetermined allowable value, it may be detected that there is an abnormality of the main power supply 18 due to an abnormal voltage rise.

[0045] When the operation control unit 70 of the control device 16 does not acquire an abnormality detection signal from the abnormality detector 80, that is, when there is no abnormality in the main power supply 18, it operates the drive actuator 14 using the power supplied from the main power supply 18. At this time, the drive actuator 14 is operated by operating each electromechanical device (prime mover 22, transmission actuator 26, etc.) used for the drive actuator 14 using the power supplied from the main power supply 18. On the other hand, when the operation control unit 70 acquires an abnormality detection signal output from the abnormality detector 80 during the operation of the drive actuator 14, it performs the above-described operation stop control and gear ratio change control using the power supplied from the auxiliary power supply 20. At this time, the operation stop control and the like are performed by operating each electromechanical device using the power supplied from the auxiliary power supply 20. When an abnormality detection signal is acquired during the operation of the drive actuator 14, the power supply used for the drive actuator 14 is switched from the main power supply 18 to the auxiliary power supply 20. Thereby, even when an abnormality occurs in the main power supply 18, after the gear ratio change control is performed using the power supplied from the auxiliary power supply 20 by the operation control unit 70 of the control device 16, the drive actuator 14 can shift to the operation stop state.

[0046] Next, the characteristics of the transmission actuator 26 will be described. Refer to FIG. 3. The transmission actuator 26 includes a power source 26a that generates power, a transmission mechanism 26b that transmits the power generated by the power source 26a, and an output unit 26c that outputs the power transmitted from the transmission mechanism 26b to the transmission 24. The actual gear ratio of the transmission 24 is changed by the gear ratio change mechanism 46 when the power output from the output unit 26c is input to the gear ratio change mechanism 46 of the transmission 24.

[0047] The power source 26a of this embodiment is a motor that generates rotational power. The transmission mechanism 26b of this embodiment is a feed screw mechanism, and includes a screw shaft 26d that is rotated by the power source 26a, and a ball nut 26e that is linearly movable as the screw shaft 26d rotates. A spiral first screw groove (not shown) is formed on the outer peripheral surface of the screw shaft 26d, a spiral second screw groove (not shown) is formed on the inner peripheral surface of the ball nut 26e, and balls are arranged in the spiral space surrounded by the first and second screw grooves. The output portion 26c of this embodiment is a moving body that is linearly movable integrally with the ball nut 26e of the transmission mechanism 26b.

[0048] The transmission mechanism 26b has a self-locking function that allows power to be transmitted from the input side (power source 26a) to the output side (output portion 26c) and restricts power transmission from the output side to the input side. In order to achieve this, in the feed screw mechanism constituted by the transmission mechanism 26b, when the power source 26a generates rotational power, the rotational power is converted into the linear power of the ball nut 26e by the rotation of the screw shaft 26d accompanied by the rolling of the balls, and the converted linear power is transmitted to the output portion 26c. Thereby, power transmission from the input side to the output side is allowed. On the other hand, when linear power is transmitted from the output portion 26c to the ball nut 26e, the movement of the screw shaft 26d due to the linear power is restricted by the contact between the screw grooves of the ball nut 26e and the screw shaft 26d and the balls in the spiral space, and the transmission of the linear power to the power source 26a is restricted. Thereby, power transmission from the output side to the input side is restricted by the self-locking function. This self-locking function is also realized when the shift actuator 26 is in a non-energized state where no power is supplied.

[0049] When changing the actual gear ratio of the transmission 24 by this self-locking function, the power generated by consuming electric power by the power source 26a can be transmitted from the input side to the output side, thereby changing the actual gear ratio. Further, during the operation of the drive actuator 14, a force to change the actual gear ratio of the transmission 24 may act, and in this case, power may be transmitted from the output side to the input side to the transmission actuator 26. In this case, the transmission of power from the output side to the input side is restricted by the self-locking function of the transmission actuator, so that the actual gear ratio of the transmission 24 can be maintained without supplying power to the transmission actuator 26. Therefore, compared with the case where power supply to the transmission actuator 26 is always required to maintain the actual gear ratio of the transmission 24, the energy consumption and the calorific value of the transmission actuator 26 can be reduced, and the energy saving property can be improved.

[0050] The specific configuration for realizing the transmission mechanism 26b having the self-locking function is not particularly limited. For example, a combination of a worm and a worm wheel known to have such a self-locking function may be used. Further, the transmission actuator 26 may not include the transmission mechanism 26b having the self-locking function. In this case, the transmission actuator 26 may be configured using, for example, an electromagnetic solenoid or the like without using a feed screw mechanism.

[0051] (Second Embodiment) Next, another usage example of the actuator unit will be described. Refer to FIG. 4. Here, an example in which the actuator unit is used for the robot 90 is shown. The robot 90 of the present embodiment is a collaborative robot for working in cooperation with a human, but its specific example is not particularly limited, and it may be various industrial robots or service robots.

[0052] The robot 90 of this embodiment is a multi-joint robot with six joints. The number of joints is not particularly limited and may be any of two to five, or seven or more. The robot 90 includes a plurality of joint portions 92A to 92F and a plurality of robot members 94A to 94G that are serially connected by the plurality of joint portions 92A to 92F. The robot member 94A on the most proximal side in the robot 90 serves as a base member, and the robot members 94B to 94G on the more distal side thereof serve as arm members. An attachment 96 such as a gripper is detachably mounted on the most distal robot member 94G (arm member).

[0053] The robot 90 includes actuator units 10A to 10F incorporated in the respective joint portions 92A to 92F and driving the joint portions 92A to 92F. Here, "driving the joint portion" means rotating (changing the relative position) the distal arm member with respect to the proximal arm member connected by the joint portions 92A to 92F. In this case, the driven device 12 described above becomes the distal arm member connected by the joint portions 92A to 92F. In this embodiment, there are a first joint portion 92A, a second joint portion 92B, ··· a sixth joint portion 92F, and first actuator units 10A, second actuator units 10B ··· sixth actuator units 10F incorporated therein. Here, the first joint portion 92A and the sixth joint portion 92F on the most proximal side and the most distal side are rotatable around a vertical axis, and the other joint portions 92B to 92E are rotatable around a horizontal axis.

[0054] Each of the actuator units 10A to 10F has the same configuration as the actuator unit of the first embodiment. The setting units 72 of the control devices 16 of each of the actuator units 10A to 10F can set the set reduction ratio independently of each other. For example, the control device 16 of the first actuator unit 10A can set the lock reduction ratio as the set reduction ratio, and the control device 16 of the second actuator unit 10B can set the rotation allowable reduction ratio as the set reduction ratio.

[0055] Accordingly, when each of the actuator units 10A to 10F used in the robot 90 is in the operation stop state, by changing the set reduction ratio set for each of the actuator units 10A to 10F used for the respective joint portions 92A to 92F, the degree of rotation suppression for each of the joint portions 92A to 92F can be changed. Therefore, the flexibility of the operation of the robot 90 can be enhanced as compared with the case where the degree of rotation suppression is the same for all of the joint portions 92A to 92F. For example, consider a case where only the actuator units 10A and 10F used for the joint portions 92A and 92F that can rotate around the vertical axis are set to the locked reduction ratio, and the actuator units 10B to 10E used for the other joint portions 92B to 92E are set to the rotation-permitted reduction ratio. In this case, while avoiding the situation where the joint portions 92A and 92F of the robot 90 rotate around the vertical axis, position adjustment at the other joint portions 92B to 92E can be allowed. Also, when the actuator units 10 used for the joint portions 92B to 92E that can rotate around the horizontal axis of the robot 90 are set to the locked reduction ratio, there is also an advantage that sagging due to rotation by its own weight around the horizontal axis can be suppressed.

[0056] Note that the collaborative robot is used in a wide range of applications in various industries such as food, logistics, and the food service industry, as compared with the industrial robot mainly for simple operations in the manufacturing industry. For this reason, it often works near people, and the requirement for operation flexibility is higher than that of the industrial robot used for simple operations. When used in such a collaborative robot, it is advantageous in that the operation flexibility can be enhanced as described above.

[0057] A modified form of the above embodiment will be described. The setting unit 72 of the control device 16 does not necessarily have to be able to variably set the set gear ratio. In this case, the set gear ratio will be set as a fixed value that cannot be changed. So far, the setting unit 72 has been described with an example in which, when variably setting the set gear ratio, either the lock gear ratio or the rotation allowable gear ratio can be set as the set gear ratio. In addition to this, the setting unit 72 may not be configured to set the lock gear ratio as the set gear ratio when variably setting the set gear ratio, and may be able to set the set gear ratio stepwise or continuously only within the rotation allowable gear ratio range.

[0058] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be interpreted limitedly to the content of the embodiments. Many design changes such as changes, additions, deletions, etc. of components are possible for the content of the embodiments. In the above-described embodiments, regarding the content for which such design changes are possible, the notation "embodiment" is added and emphasized. However, design changes are also allowed for the content without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached. Also, any substitution of any of the components and expressions of the present disclosure between a method, an apparatus, a system, etc. is also valid as an aspect of the present disclosure.

Explanation of Reference Numerals

[0059] 10... Actuator unit, 10A... First actuator unit, 10B... Second actuator unit, 12... Driven device, 14... Driving actuator, 16... Control device, 18... Main power supply, 20... Auxiliary power supply, 22... Prime mover, 24... Transmission, 26... Shift actuator, 70... Operation control unit, 72... Setting unit, 90... Robot, 92A... First joint part, 92B... Second joint part.

Claims

1. An operation control unit for controlling the operation of a drive actuator, the drive actuator including a prime mover, a transmission that changes the rotation input from the prime mover and outputs the rotation to a driven device, and a transmission actuator that can change the actual transmission ratio of the transmission. When the operation control unit attempts to stop the operation of the drive actuator, the control device performs a transmission ratio change control for changing the actual transmission ratio to a preset set transmission ratio by the transmission actuator.

2. The operation control unit changes the actual transmission ratio to a lock transmission ratio that is set as the set transmission ratio and is preset as a transmission ratio for locking the rotation of the driven device in the transmission ratio change control. The control device according to claim 1.

3. The control device according to claim 1, further including a setting unit for variably setting the set transmission ratio.

4. The setting unit can set either a lock transmission ratio preset as a transmission ratio for locking the rotation of the driven device or a rotation allowable transmission ratio preset as a transmission ratio for allowing the rotation of the driven device as the set transmission ratio. The control device according to claim 3.

5. The setting unit can change the set transmission ratio stepwise or continuously within a rotation allowable transmission ratio range preset as a transmission ratio range for allowing the rotation of the driven device. The control device according to claim 3.

6. When an abnormality occurs in the main power supply that supplies power to the drive actuator, the operation control unit performs the transmission ratio change control using the power supplied from the auxiliary power supply. The control device according to claim 1.

7. A drive actuator according to any one of claims 1 to 6, An actuator unit including a control device according to any one of claims 1 to 6.

8. The transmission actuator has a self-lock function that allows power transmission from the input side to the output side and restricts power transmission from the output side to the input side. The actuator unit according to claim 7.

9. A first joint portion, A first actuator unit that is the actuator unit according to claim 7 incorporated in the first joint portion, A second joint portion, A robot including a second actuator unit that is the actuator unit according to claim 7 incorporated in the second joint portion. The control devices of the first actuator unit and the second actuator unit are robots that can set the set gear ratio independently of each other.

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