Control device, actuator unit, and robot

Abstract

This control device comprises an operation control unit 70 for controlling an operation of a drive actuator 14 including a prime mover 22, a transmission 24 that changes the speed of rotation input from the prime mover 22 and outputs the rotation to a driven device 12, and a speed change actuator 26 capable of changing an actual speed ratio of the transmission 24. When the operation of the drive actuator 14 is to be stopped, the operation control unit 70 performs speed ratio change control for changing the actual speed ratio to a preset speed ratio by the speed change actuator 26.

Description

Control device, actuator unit and robot

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

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

[0003] Japanese Patent Application Laid-Open No. 2020-205742

[0004] When a transmission with a variable gear ratio is used, the gear ratio can change in various ways while the drive actuator is operating. Furthermore, when the drive actuator is stopped, the degree to which the transmission suppresses the rotation of the driven device varies depending on the gear ratio of the transmission. Therefore, there is a problem that each time the drive actuator is stopped, the degree to which the transmission suppresses the rotation of the driven device fluctuates depending on the gear ratio used immediately before the drive actuator was stopped.

[0005] Therefore, one object of the present disclosure is to provide a technology that can suppress fluctuations in the degree to which the rotation of the driven device is suppressed by the transmission when the drive actuator is in a stopped state.

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

[0007] According to the present disclosure, when the drive actuator is in a stopped state, fluctuations in the degree to which the transmission suppresses the rotation of the driven device can be suppressed.

[0008] It is a block diagram of the actuator unit of the first embodiment. It is a side cross-sectional view of the transmission of the first embodiment. It is a schematic diagram of the gear change actuator of the first embodiment. It is a schematic diagram showing an example of use of the actuator unit of the second embodiment.

[0009] Hereinafter, an embodiment for implementing the drive actuator of the present disclosure will be described. The same or equivalent elements will be given the same reference numerals, and duplicate explanations will be omitted. In each drawing, for the sake of convenience, components will be omitted, enlarged, or reduced as appropriate. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] (First embodiment) Refer to Fig. 1 . An actuator unit 10 is used to drive a 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 rotational drive unit 12a that is rotationally driven by the actuator unit 10. The rotational drive unit 12a is, for example, a screw shaft used in the ball screw device. Specific examples of the driven device 12 are not particularly limited, and may be part of an industrial machine (machine tool, construction machine, etc.), a robot (industrial robot, service robot, etc.), transportation equipment (conveyor, vehicle, etc.), or the like.

[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 power supplied from an external main power supply 18 or auxiliary power supply 20. The main power supply 18 is, for example, a commercial power supply. The auxiliary power supply 20 is, for example, an uninterruptible power system (UPS), an output hold time extension module, etc.

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

[0013] The prime mover 22 is capable of rotating a drive shaft (not shown) using torque generated therein and outputting the rotation from the drive shaft to the transmission 24. The prime mover 22 in this embodiment is a motor (electric motor) that rotates the drive shaft using electrical energy. The motor can rotate the drive shaft using torque generated by the cooperation of a stator and a rotor. There are no particular limitations on the specific example of the prime mover 22, and it may be, for example, an engine that rotates the drive shaft using thermal energy.

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

[0015] Referring to Figure 2, the transmission 24 includes an input shaft 40 to which rotation is input from the prime mover 22, a speed change mechanism 42 that changes the speed of the rotation input to the input shaft 40 and then transmits it to an output shaft 44, the output shaft 44 that outputs the rotation transmitted from the speed change mechanism 42 to a driven device, and a speed ratio change mechanism 46 that changes the speed ratio of the speed change mechanism 42.

[0016] The transmission 24 of this embodiment is capable of continuously (steplessly) changing the actual gear ratio, which is the actual gear ratio, using the gear ratio changing mechanism 46 via the gear actuator 26. The gear ratio here refers to the ratio of the output rotational speed, which is the rotational speed of the output shaft 44, to the input rotational speed, which is the rotational speed of the input shaft 40 (= output rotational speed / input rotational speed). The transmission 24 of this embodiment is an infinitely variable transmission (IVT) with an infinitely variable gear ratio, and is configured so that the variable range of the actual gear ratio includes zero (= 1 / ∞). While an example of such a transmission 24 will be described here, the specific example is not particularly limited. For example, the transmission 24 may be a toroidal continuously variable transmission or the like. Furthermore, the variable range of the transmission 24 may not include zero. 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. Furthermore, the transmission 24 may be a transmission that can change the gear ratio in steps, instead of a continuously variable transmission that can change the gear ratio continuously.

[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. Here, the input shaft 40 is shown as being made up of multiple members, but it may also be made up of a single member, and the number of members is not particularly limited.

[0018] The transmission mechanism 42 includes an input bearing ring 50 provided on the input shaft 40 so as to be rotatable therewith, a first support bearing ring 52 rotatably supported on the input shaft 40, a second support bearing ring 56 provided axially movably within a casing 54 of the transmission 24, an output bearing ring 58 provided on the output shaft 44 so as to be rotatable therewith, and a plurality of planetary rolling elements 60 that roll on the bearing rings 50, 52, 56, 58. The plurality of planetary rolling elements 60 are pressed against the output bearing ring 58 by a pressing force applied from the second support bearing ring 56 by a pressing force applying mechanism (not shown).

[0019] When the input bearing ring 50 rotates, the planetary rolling elements 60 rotate about the rotation axis L60 while revolving around the rotation axis L40 (revolution axis) of the input shaft 40. As the planetary rolling elements 60 revolve, the output bearing ring 58 rotates about the rotation axis L40 in response. Ideally, the output bearing ring 58 rotates at an output rotation speed obtained by multiplying the input rotation speed of the input shaft 40 by the gear ratio. This gear 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 gear ratio change mechanism 46.

[0020] The output shaft 44 includes an output bearing ring 58 and an output member 44a that is connected to the output bearing ring 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 is shown as being made up of multiple members, but it may also be made up of a single member, and the number of members is not particularly limited.

[0021] The gear ratio change mechanism 46 of this embodiment is able to change the gear ratio by changing the position of the input bearing ring 50. The gear ratio change mechanism 46 includes a shaft 46a that is movable in the axial direction by power output from the gear change actuator 26, and a ring member 46b that is movable in the axial direction integrally with the shaft 40b. The ring member 46b rotatably supports the input shaft 40 via a bearing 46c, and is able to move in the axial direction integrally with the input shaft 40 by a snap ring or the like. There are no particular limitations on the specific example of the gear ratio change mechanism 46, and various mechanisms similar to those employed in the transmission 24 may be employed.

[0022] When axial power is input from the speed change actuator 26 to the shaft 46a, the input shaft 40 (including the input race 50 and the first support race 52) moves axially together with the ring member 46b. The axial movement of the input race 50 and the first support race 52 relative to the second support race 56 and the output race 58 changes the inclination angle of the rotation axis L60 of the planetary rolling elements 60 relative to the rotation axis L40, changing the gear ratio according to that inclination angle. This gear ratio is 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 relative to the rotation axis L40 increases. In other words, the actual gear ratio can be changed continuously (steplessly), and the variable range is configured to include zero.

[0023] Returning to FIG. 1 , the control device 16 is configured by a combination of hardware and software elements, or by hardware elements only. Examples of hardware elements include a processor, a read-only memory (ROM), and a random access memory (RAM). Examples of software elements include an operating system, an application program, and other programs. The portion used to control the prime mover 22 and the portion used to control the speed change actuator 26 may be realized by common hardware or software elements, or may be realized by separate hardware or software elements. The control device 16 is attached to the drive actuator 14 and can be handled as an integrated unit 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 gear ratio (described later) used for control by the operation control unit 70, and a storage unit 74 that stores data used for control by the operation control unit 70. The operation control unit 70 controls the operation of the prime mover 22, thereby changing the torque generated by the prime mover 22. The operation control unit 70 controls the operation of the gear change actuator 26, thereby changing the gear ratio of the transmission 24.

[0025] When a predetermined operation stop condition (described later) is satisfied, the operation control unit 70 performs operation stop control to stop the operation of the drive actuator 14 by controlling the drive actuator 14. This operation stop control is performed when it is desired 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. Here, the power transmission elements refer to elements used to transmit the torque (power) generated by the prime mover 22 to the driven device 12, such as the drive shaft of the prime mover 22, the input shaft 40, the speed change mechanism 42, and the output shaft 44 of the transmission 24.

[0026] This operation stop control may be performed, for example, by causing the prime mover 22 to generate a braking torque for braking each power transmission element of the drive actuator 14. In this case, if an electric motor capable of generating regenerative braking is used as the prime mover 22, the prime mover 22 may generate regenerative energy while generating a braking torque. Alternatively, if the drive actuator 14 is equipped with a brake device, this operation stop control may be performed by causing the brake device to generate a braking torque. Alternatively, 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 brake device.

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

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

[0029] The operation control unit 70 completes the operation stop control when the operation of each power transmission element of the drive actuator 14 has stopped, that is, when the operation of the drive actuator 14 has stopped. The stop of operation of the drive actuator 14 may be detected by detecting the stop of rotation of each power transmission element of the drive actuator 14 using a rotation detector (not shown). When the drive actuator 14 enters an operation stop state, the operation control unit 70 may stop the supply of power to each electric machine (prime mover 22, speed change actuator 26, etc.) used in the drive actuator 14. This causes each electric machine to enter a non-energized state.

[0030] Before explaining the set speed ratio set by the setting unit 72, the underlying concept will be explained. When the actual speed ratio of the transmission 24 is set to zero or a value very close to zero, the transmission 24 enters a locked state (self-locked state) in which rotation of the output side (output shaft 44) of the transmission 24 together with the driven device 12 is locked. This locked state refers to a state in which it is difficult to rotate the transmission 24 from the output side, that is, a state in which it is difficult to rotate the driven device 12 (the rotational drive unit 12a of the driven device 12). In this state, the input side (input shaft 40) of the transmission 24 can be rotated, but because the actual speed ratio is very small, the output side of the transmission 24 cannot be rotated at all or very little. In contrast, when the actual speed ratio of the transmission 24 is set away from zero, a rotation-permitted state is entered in which rotation of the output side of the transmission 24 together with the driven device 12 is permitted.

[0031] The setting unit 72 variably sets the set gear ratio used in the gear ratio change control described above. The set gear ratio is set as a changeable variable value. After setting the set gear ratio, the setting unit 72 stores the set gear ratio in the memory unit 74. The setting unit 72 can set, as the set gear ratio, either a lock gear ratio that is predetermined as a gear ratio of the transmission 24 for locking the rotation of the driven device 12, or a rotation allowable gear ratio that is predetermined as a gear ratio for allowing the rotation of the driven device 12. The lock gear ratio is a gear ratio that is predetermined as a gear ratio for locking the rotation of the driven device 12 to achieve the locked state described above. The rotation allowable gear ratio here is a gear ratio that is predetermined as a gear ratio for allowing the rotation of the driven device 12 to achieve the rotation allowable state described above. For example, the lock gear ratio is set within a gear ratio range of zero (= 1 / ∞) to 1 / thousands, and the allowable rotation gear ratio is set within a gear ratio range of 1 / 200 to 1 / tens. The gear ratio ranges given here are merely examples, and other gear ratio ranges may also be set.

[0032] The setting unit 72 may set the set gear ratio in accordance with a command from a user or an external controller. The external controller here refers to, for example, a host controller that comprehensively controls the operations of the multiple drive actuators 14. When setting the set gear ratio in accordance with a user's command, the drive actuator 14 may include a first operation unit that outputs the specified gear ratio specified by the user through a user operation to the control device 16 as a user command. In this case, the setting unit 72 may set the specified gear ratio output from the first operation unit as the set gear ratio. The first operation unit may be, for example, configured by a switch or the like provided on a control panel, or an information processing terminal such as a touch panel.

[0033] The setting unit 72 may be able to change the set gear ratio continuously or stepwise within a predetermined rotation allowable gear ratio range that is a gear ratio range for allowing rotation of the driven device 12. The setting unit 72 of this embodiment can set the set gear ratio to the locked gear ratio, or can set the set gear ratio to one of a plurality of rotation allowable gear ratios. This rotation allowable gear ratio range may be, for example, the aforementioned gear ratio range of 1 / 200 to 1 / tens.

[0034] When the setting unit 72 sets the lock speed ratio as the set speed ratio, the operation control unit 70 changes the actual speed ratio of the transmission 24 to the lock speed ratio in the speed ratio change control. This allows the drive actuator 14 to enter a locked state in which rotation of the driven device 12 is locked when the drive actuator 14 is in an operation stop state. In this case, the operation control unit 70 can change the actual speed ratio of the transmission 24 from the lock speed ratio to the rotation allowable speed ratio by the speed change actuator 26 after starting operation of the drive actuator 14 and before starting driving of the driven device 12.

[0035] When the setting unit 72 sets the rotation allowable speed ratio as the set speed ratio, the operation control unit 70 changes the actual speed ratio of the transmission 24 to the rotation allowable speed ratio in the speed ratio change control. As a result, when the driving actuator 14 is in an operation stop state, the driven device 12 can be brought into a rotation allowable state in which rotation is allowed.

[0036] The effects of the control device 16 described above will now be explained. When the operation of the drive actuator 14 is to be stopped, the operation control section 70 of the control device 16 performs gear ratio change control, which changes the actual gear ratio of the transmission 24 to the set gear ratio using the speed change actuator 26. Therefore, the actual gear ratio when the drive actuator 14 is in the stopped state can be set to the set gear ratio, regardless of the actual gear ratio used immediately before the operation of the drive actuator 14 was stopped. Therefore, when the drive actuator 14 is in the stopped state, fluctuations in the degree to which the transmission 24 suppresses the rotation of the driven device 12 can be suppressed.

[0037] Consider a case in which, when the drive actuator 14 is in a stopped state, the power transmission element of the drive actuator 14 is braked by a non-excitation actuated brake to lock the rotation of the driven device 12. In this case, a constant supply of power to the non-excitation actuated brake is required to release the braking applied by the non-excitation actuated brake, resulting in problems such as increased energy consumption and heat generation. In this regard, the operation control unit 70 of this embodiment can change the actual gear ratio of the transmission 24 to a locked gear ratio by using gear ratio change control. Therefore, when the drive actuator 14 is in a stopped state, the actual gear ratio of the transmission 24 can be changed to the locked gear ratio in advance by using gear ratio change control, thereby allowing the transmission 24 to lock the rotation of the driven device 12. Furthermore, to release the lock by the transmission 24, it is only necessary to change the actual gear ratio of the transmission 24 by the gear change actuator 26, and a constant supply of power is not required, as is the case when a non-excitation actuated brake is used. Therefore, it is possible to advantageously solve the problems of increased energy consumption and heat generation, while locking the rotation of the driven device 12 when the device is in an operation-stopped state.

[0038] The control device 16 includes a setting unit 72 that variably sets the set speed ratio. Therefore, by changing the set speed ratio set by the setting unit 72, it becomes possible to adjust the degree to which the transmission 24 restrains rotation of the driven device 12 when the drive actuator 14 is in an operation-stopped state. This allows the actual degree of rotation restraint to be adjusted according to the required degree of rotation restraint of the driven device 12, thereby increasing the flexibility of operation of the drive actuator 14.

[0039] The setting unit 72 can selectively set, as the set gear ratio, either a lock gear ratio for locking the rotation of the driven device 12 or a rotation allowable gear ratio for allowing the rotation. 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 an operation stop state, it is possible to select either a locked state or a rotation allowable state as the state of the driven device 12. This can further increase the flexibility of operation of the drive actuator 14.

[0040] It is conceivable that the state of the driven device 12 can be selected between the locked state and the rotation permitted state by modifying the hardware. Here, modifying the hardware means switching between incorporating an electromagnetic brake into the drive actuator 14. In this regard, this embodiment has the advantage that the state of the driven device 12 can be selected between the locked state and the rotation permitted state simply by changing the set speed ratio without modifying the hardware.

[0041] The setting unit 72 can change the set gear ratio in a stepwise or continuous manner within a predetermined rotation allowable gear ratio range as a gear ratio range within which rotation of the driven device 12 is allowable. This makes it possible to adjust the degree to which the transmission 24 suppresses rotation of the driven device while allowing rotation of the driven device 12 when the drive actuator 14 is in an operation-stopped state. This further increases the flexibility of operation of the drive actuator.

[0042] Next, the above-mentioned operation stop conditions will be described. The operation stop conditions include, for example, (1) receiving an operation stop command from a user or an external controller, and (2) occurrence of an abnormality in the main power supply 18.

[0043] When receiving the operation stop command from the user in (1), the drive actuator 14 may include a second operation unit for outputting the operation stop command to the control device 16 in accordance with the user's operation. This second operation unit may be configured, for example, as a switch provided on a control panel or an information processing terminal such as a touch panel. This switch may be a power switch that switches on and off the supply of power to the drive actuator 14. In this case, the second operation unit may output the operation stop command to the control device 16 by an OFF operation to stop the power supply. When the condition in (1) is satisfied, the operation control unit 70 may operate each electric machine (prime mover 22, speed change actuator 26, etc.) used in the drive actuator 14 using power supplied from the main power supply 18 to perform the above-mentioned operation stop control and gear ratio change control. Alternatively, the operation control unit 70 may operate each electric machine using power supplied from the auxiliary power supply 20.

[0044] (2) will be explained. An abnormality detector 80 is provided outside the drive actuator 14 to detect an abnormality in the main power supply 18. When the abnormality detector 80 detects an abnormality in the main power supply 18, it outputs an abnormality detection signal indicating the abnormality 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 outage of the main power supply 18, an abnormal voltage drop or abnormal voltage rise of the power supplied from the main power supply 18, etc. The abnormality detector 80 may detect an abnormality in the main power supply 18 using various detection methods, including publicly known methods. For example, if the voltage value of the power supplied from the main power supply 18 exceeds a predetermined allowable value, it may detect that an abnormality in the main power supply 18 has occurred due to an abnormal voltage rise.

[0045] When the operation control unit 70 of the control device 16 does not receive an abnormality detection signal from the abnormality detector 80, that is, when no abnormality has occurred in the main power supply 18, it operates the drive actuator 14 using power supplied from the main power supply 18. At this time, the drive actuator 14 is operated by operating each electric machine (prime mover 22, variable speed actuator 26, etc.) used in the drive actuator 14 using power supplied from the main power supply 18. On the other hand, when the operation control unit 70 receives an abnormality detection signal output from the abnormality detector 80 while the drive actuator 14 is in operation, it performs the above-mentioned operation stop control and gear ratio change control using power supplied from the auxiliary power supply 20. At this time, the operation stop control, etc. is performed by operating each electric machine using power supplied from the auxiliary power supply 20. When an abnormality detection signal is received while the drive actuator 14 is in operation, the power source used for the drive actuator 14 is switched from the main power supply 18 to the auxiliary power supply 20. This means that even if an abnormality occurs in the main power supply 18, the operation control unit 70 of the control device 16 can perform gear ratio change control using power supplied from the auxiliary power supply 20, and then the drive actuator 14 can transition to a stopped state.

[0046] Next, the characteristics of the transmission actuator 26 will be described. Refer to Figure 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 a gear ratio change mechanism 46 of the transmission 24 when the power output from the output unit 26c is input to the gear ratio change mechanism 46.

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

[0048] The transmission mechanism 26b has a self-locking function that allows power transmission from the input side (power source 26a) to the output side (output section 26c) and limits power transmission from the output side to the input side. To achieve this, the feed screw mechanism constituting the transmission mechanism 26b converts rotational power generated by the power source 26a into linear power of the ball nut 26e by rotating the screw shaft 26d accompanied by ball rolling, and transmits the converted linear power to the output section 26c. This allows power transmission from the input side to the output side. On the other hand, when linear power is transmitted from the output section 26c to the ball nut 26e, contact between the balls in the helical space and the thread grooves of the ball nut 26e and the screw shaft 26d restricts the movement of the linear power caused by the linear power, thereby limiting the transmission of the linear power to the power source 26a. This self-locking function limits power transmission from the output side to the input side. This self-locking function is also realized when the speed change actuator 26 is in a non-energized state where no power is supplied to the speed change actuator 26.

[0049] This self-locking function allows power generated by consuming electric power from the power source 26a to be transmitted from the input side to the output side when the actual gear ratio of the transmission 24 is to be changed, thereby changing the actual gear ratio. Furthermore, when the drive actuator 14 is in operation, a force that attempts to change the actual gear ratio of the transmission 24 may act, causing power to be transmitted from the output side to the input side of the gear change actuator 26. In this case, the self-locking function of the gear change actuator limits the transmission of power from the output side to the input side, allowing the actual gear ratio of the transmission 24 to be maintained even when electric power is not being supplied to the gear change actuator 26. Therefore, compared to a case in which electric power must always be supplied to the gear change actuator 26 to maintain the actual gear ratio of the transmission 24, the amount of energy consumed and the amount of heat generated by the gear change actuator 26 can be reduced, resulting in improved energy savings.

[0050] The specific configuration for realizing the self-locking transmission mechanism 26b is not particularly limited. For example, a combination of a worm and a worm wheel, which are known to have such a self-locking function, may be used. Furthermore, the speed change actuator 26 does not necessarily have to include the self-locking transmission mechanism 26b. In this case, the speed change actuator 26 may be configured using an electromagnetic solenoid or the like, instead of a feed screw mechanism, for example.

[0051] (Second embodiment) Next, another example of use of the actuator unit will be described. Refer to FIG. 4. Here, an example is shown in which the actuator unit is used in a robot 90. The robot 90 in this embodiment is a collaborative robot that works in collaboration with humans, but the specific example is not particularly limited, and 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 multiple joints 92A-92F and multiple robot members 94A-94G connected in series by the multiple joints 92A-92F. The robot member 94A closest to the base end of the robot 90 serves as the base member, and the robot members 94B-94G closer to the tip end serve as arm members. An attachment 96 such as a gripper is detachably mounted on the robot member 94G (arm member) closest to the tip end.

[0053] The robot 90 includes actuator units 10A-10F incorporated into the respective joints 92A-92F to drive the joints 92A-92F. Here, "driving a joint" refers to rotating (changing the relative position of) a distal arm member relative to a proximal arm member connected by the joints 92A-92F. In this case, the driven device 12 described above is the distal arm member connected by the joints 92A-92F. In this embodiment, there are a first joint 92A, a second joint 92B, ..., a sixth joint 92F, and a first actuator unit 10A, a second actuator unit 10B, ..., a sixth actuator unit 10F incorporated therein. Here, the proximal and distal first joints 92A and 92F and the sixth joint 92F are rotatable around vertical axes, while the remaining joints 92B-92E are rotatable around horizontal axes.

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

[0055] As a result, when each of the actuator units 10A-10F used in the robot 90 is in a stopped state, the degree of rotation suppression for each of the joints 92A-92F can be changed by changing the set gear ratio set for each of the actuator units 10A-10F used in each of the joints 92A-92F. This increases the operational flexibility of the robot 90 compared to when the same degree of rotation suppression is set for all of the joints 92A-92F. For example, consider a case where only the actuator units 10A and 10F used in the joints 92A and 92F, which can rotate around a vertical axis, are set to a locked gear ratio, while the actuator units 10B-10E used in the other joints 92B-92E are set to a rotation-permitting gear ratio. In this case, rotation of the joints 92A and 92F of the robot 90 around the vertical axis can be avoided while allowing position adjustments for the other joints 92B-92E. In addition, when the actuator unit 10 used in the joints 92B to 92E that can rotate around the horizontal axis of the robot 90 is set to a locked gear ratio, there is also the advantage that sagging caused by rotation around the horizontal axis due to its own weight can be suppressed.

[0056] In addition, compared to industrial robots, which are primarily used for simple tasks in manufacturing, collaborative robots are used for a wide range of applications in various industries, such as food, logistics, and restaurant services. For this reason, they often work in close proximity to people, and there is a greater demand for operational flexibility than industrial robots used for simple tasks. When used in such collaborative robots, they have the advantage of being able to increase operational flexibility, as mentioned above.

[0057] A modification of the above embodiment will now be described. The setting unit 72 of the control device 16 does not have to be able to variably set the set gear ratio. In this case, the set gear ratio is set as an unchangeable fixed value. Up to this point, an example has been described in which the setting unit 72 is able to set either the locked gear ratio or the rotation allowable gear ratio as the set gear ratio when variably setting the set gear ratio. Alternatively, the setting unit 72 may not be configured to be able to set the locked gear ratio as the set gear ratio when variably setting the set gear ratio, but may be able to set the set gear ratio stepwise or continuously only within the rotation allowable gear ratio range.

[0058] The above-described embodiments and variations are merely examples. The abstract technical concepts should not be interpreted as being limited to the content of the embodiments. Many design modifications, such as changes, additions, and deletions of components, are possible within the content of the embodiments. In the above-described embodiments, the term "embodiment" is used to emphasize content that allows such design modifications. However, design modifications are also permitted even within content without such notation. Hatching on cross sections in the drawings does not limit the material of the hatched object. Furthermore, any of the components and expressions of the present disclosure may be mutually substituted between methods, devices, systems, etc., as aspects of the present disclosure.

[0059] The present disclosure relates to a control device for use in a drive actuator.

[0060] 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...variable speed actuator, 70...movement control unit, 72...setting unit, 90...robot, 92A...first joint unit, 92B...second joint unit.

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 it to a driven device, and a transmission actuator capable of changing the actual transmission ratio of the transmission. When the operation control unit attempts to stop the operation of the drive actuator, the transmission actuator performs a transmission ratio change control to change the actual transmission ratio to a preset set transmission ratio. A control device.

2. The control device according to claim 1, wherein in the transmission ratio change control, 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.

3. The control device according to claim 1 or 2, further comprising 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 control device according to claim 3 or 4, wherein 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.

6. The control device according to any one of claims 1 to 5, wherein 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.

7. An actuator unit including the drive actuator according to any one of claims 1 to 6 and the control device according to any one of claims 1 to 6.

8. The actuator unit according to claim 7, wherein 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.

9. A robot comprising: a first joint portion; a first actuator unit which is the actuator unit according to claim 7 or 8 incorporated in the first joint portion; a second joint portion; and a second actuator unit which is the actuator unit according to claim 7 or 8 incorporated in the second joint portion, wherein the control devices of the first actuator unit and the second actuator unit can set the set transmission ratio independently of each other.

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