Control device, actuator unit and robot

Abstract

A control device includes an action control unit (70) for controlling the action of a drive actuator (14), the drive actuator (14) comprising: a prime mover (22); a gearbox (24) for changing the speed of rotation input from the prime mover (22) and outputting it to a driven device (12); and a speed change actuator (26) capable of changing the actual gear ratio of the gearbox (24). When the action control unit (70) wants to stop the drive actuator (14) from running, it performs a speed ratio change control, that is, changes the actual gear ratio to a preset gear ratio through the speed change actuator (26).

Description

Technical Field

[0001] This invention relates to a control device for driving actuators. Background Technology

[0002] Patent Document 1 discloses a drive actuator comprising a prime mover and a gearbox, wherein the gearbox outputs a variable speed input from the prime mover to the driven device. In the gearbox of Patent Document 1, the ratio of the rotational speed of the output shaft to the rotational speed of the input shaft, i.e., the gear ratio, is a fixed ratio.

[0003] Previous technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2020-205742 Summary of the Invention

[0004] The technical problem to be solved by the invention When using a variable-ratio transmission, the gear ratio may change during the operation of the actuator. Furthermore, when the actuator is in a stopped state, the degree to which the transmission suppresses the rotation of the driven device varies depending on the transmission's gear ratio. Therefore, the following problem exists: each time the actuator stops operating, the degree to which the transmission suppresses the rotation of the driven device changes due to the gear ratio used just before the stop.

[0005] Therefore, one of the objectives of this invention is to provide a technique that can suppress changes in the degree of rotational suppression of the driven device by the transmission when the drive actuator is in a stopped state.

[0006] means for solving technical problems The control device of the present invention includes an action control unit for controlling the action of a drive actuator. The drive actuator includes: a prime mover; a gearbox that outputs rotational input from the prime mover to a driven device after speed change; and a gearbox actuator capable of changing the actual gear ratio of the gearbox. When it is desired to stop the drive actuator, the action control unit performs gear ratio change control, that is, changes the actual gear ratio to a preset gear ratio via the gearbox actuator.

[0007] Invention Effects According to the present invention, when the drive actuator is in a stopped state, it is possible to suppress changes in the degree of rotational suppression of the driven device by the transmission. Attached Figure Description

[0008] Figure 1 This is a block diagram of the actuator unit in the first embodiment.

[0009] Figure 2 This is a side sectional view of the transmission according to the first embodiment.

[0010] Figure 3 This is a schematic diagram of the variable speed actuator according to the first embodiment.

[0011] Figure 4 This is a schematic diagram illustrating an example of the use of the actuator unit according to the second embodiment. Detailed Implementation

[0012] The following describes embodiments of the drive actuator used to implement the present invention. Identical or equivalent elements are labeled with the same reference numerals, and repeated descriptions are omitted. In the figures, for ease of explanation, constituent elements are appropriately omitted, enlarged, or reduced. The figures are viewed according to the orientation of the reference numerals.

[0013] (First Implementation Method) Reference Figure 1 The actuator unit 10 drives the driven device 12. The driven device 12 is, for example, a ball screw device used in conveying devices, positioning devices, etc. The driven device 12 includes a rotary drive unit 12a that is rotated by the actuator unit 10. The rotary 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 also be a component of industrial machinery (machine tools, construction machinery, etc.), robots (industrial robots, service robots, etc.), conveying equipment (conveyors, vehicles, etc.).

[0014] 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 supply (UPS), an output hold-up time extension module, etc.

[0015] The drive actuator 14 includes: a prime mover 22; a gearbox 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 gearbox 24. Hereinafter, when referring to the rotation of the driven device 12 and the prime mover 22, it refers to the rotation of the entire object rotating within the mentioned object. For example, when referring to the rotation of the driven device 12, it refers to the rotation of the entire object rotating within the driven device 12 (such as the rotation drive unit 12a), and when referring to the rotation of the prime mover 22, it refers to the rotation of the entire object rotating within the prime mover 22 (such as the drive shaft).

[0016] The prime mover 22 can rotate the prime shaft (not shown) using the torque generated within it, and output the rotational speed from the prime shaft to the transmission 24. In this embodiment, the prime mover 22 is a motor (electric motor) that uses electrical energy to drive the prime shaft. The motor can drive the prime shaft to rotate using the torque generated by the cooperation of the stator and rotor. Specific examples of the prime mover 22 are not particularly limited; for example, it could be an engine that uses heat energy to drive the prime shaft.

[0017] The transmission actuator 26 can change the gear ratio of the transmission 24 by inputting power to the transmission 24. In this embodiment, the transmission actuator 26 is a linear actuator that inputs power along the axial direction of the transmission 24 to the transmission 24. The specific type of transmission actuator 26 is not particularly limited as long as it can change the gear ratio of the transmission 24; it can also be a rotary actuator or the like.

[0018] refer to Figure 2 The transmission 24 includes: an input shaft 40 for receiving rotation from the prime mover 22; a transmission mechanism 42 for changing the speed of the rotation input to the input shaft 40 and transmitting it to an output shaft 44; an output shaft 44 for outputting the rotation transmitted from the transmission mechanism 42 to a driven device; and a gear ratio changing mechanism 46 for changing the gear ratio of the transmission mechanism 42.

[0019] The transmission 24 of this embodiment can drive the gear ratio changing mechanism 46 via the gear actuator 26 to continuously change the actual gear ratio (i.e., the actual gear ratio). Here, the gear ratio refers to the ratio of the rotational speed of the output shaft 44 (output speed) to the rotational speed of the input shaft 40 (input speed) (=output speed / input speed). The transmission 24 of this embodiment is an infinitely variable transmission (IVT), configured to include zero (=1 / ∞) within the variable range of the actual gear ratio. Here, one example of such a transmission 24 is described, but the specific example is not particularly limited. For example, the transmission 24 could also be a toroidal type VVT. Alternatively, the transmission 24 could not include zero within the variable range. In this case, the VVT ​​could be, for example, a belt-type VVT, a chain-type VVT, etc. Furthermore, instead of a continuously variable transmission capable of changing the gear ratio continuously, a transmission capable of changing the gear ratio in steps could be used instead of the transmission 24.

[0020] The input shaft 40 includes: an input component 40a for inputting rotation from the prime mover 22; a shaft 40b connected to the input component 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 shown here is an example composed of multiple components, but it can also be composed of a single component, and the number of components is not particularly limited.

[0021] The transmission mechanism 42 includes: an input raceway 50 configured to rotate integrally with the input shaft 40; a first support raceway 52 rotatably supported on the input shaft 40; a second support raceway 56 configured to move axially within the housing 54 of the transmission 24; an output raceway 58 configured to rotate integrally with the output shaft 44; and a plurality of planetary rolling elements 60 rolling on each of the raceways 50, 52, 56, and 58. The plurality of planetary rolling elements 60 are pressed onto the output raceway 58 by means of a pressing force (not shown) applied by the second support raceway 56.

[0022] If the input raceway 50 rotates, the planetary rolling elements 60 rotate around their own axis L60 and simultaneously revolve around the axis of rotation L40 (revolution axis) of the input shaft 40. If the planetary rolling elements 60 revolve, the output raceway 58 rotates synchronously around the axis of rotation L40. Ideally, the output raceway 58 rotates at the output speed obtained by multiplying the input speed of the input shaft 40 by the gear ratio. This gear ratio is determined by the tilt angle of the axis of rotation L60 relative to the axis of rotation L40 and is changed by the gear ratio changing mechanism 46.

[0023] The output shaft 44 includes an output raceway ring 58 and an output component 44a, which is integrally rotated with the output raceway ring 58 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 transmission mechanism 42 to the driven device 12. The example shown here of the output shaft 44 is composed of multiple components, but it can also be composed of a single component, and the number of components is not particularly limited.

[0024] The gear ratio changing mechanism 46 of this embodiment can change the gear ratio by changing the position of the input raceway ring 50. The gear ratio changing mechanism 46 includes: a shaft 46a, which can move axially by power output from the gear shift actuator 26; and an annular member 46b, which can move axially integrally with the shaft 40b. The annular member 46b supports the input shaft 40 rotatably via a bearing 46c, and can move axially integrally with the input shaft 40 via a retaining ring or the like. Specific examples of the gear ratio changing mechanism 46 are not particularly limited, and various mechanisms similar to those used in the transmission 24 can be employed.

[0025] If axial power is input from the transmission actuator 26 to the shaft 46a, the input shaft 40 (including the input raceway 50 and the first support raceway 52) will move axially as a unit along with the annular component 46b. The input raceway 50 and the first support raceway 52 move axially relative to the second support raceway 56 and the output raceway 58, thereby changing the tilt angle of the planetary rolling element 60's rotation axis L60 relative to the rotation axis L40, and changing the gear ratio to a value corresponding to this tilt angle. When the rotation axis L60 is parallel to the rotation axis L40, the gear ratio is zero (=1 / ∞); as the tilt angle of the rotation axis L60 relative to the rotation axis L40 increases, the gear ratio continuously increases. That is, it is configured to be able to change the actual gear ratio steplessly (continuously), and this variable range includes zero.

[0026] Return to Figure 1 The control device 16 is composed of a combination of hardware and software elements, or only hardware elements. Hardware elements include, for example, a processor, ROM (Read Only Memory), and RAM (Random Access Memory). Software elements include, for example, an operating system, application programs, etc. The parts controlling the prime mover 22 and the parts controlling the speed changer 26 can be implemented using common hardware or software elements, or they can be implemented using independent hardware or software elements. The control device 16 is mounted on the drive actuator 14 and can operate integratedly with the drive actuator 14.

[0027] The control device 16 includes: a motion control unit 70 for controlling the operation of the drive actuator 14; a setting unit 72 for variably setting the gear ratio (described later) used by the motion control unit 70 when performing control; and a storage unit 74 for storing data required by the motion control unit 70 when performing control. The motion control unit 70 can change the torque output by controlling the operation of the prime mover 22. The motion control unit 70 can change the gear ratio of the transmission 24 by controlling the operation of the transmission actuator 26.

[0028] When the preset operation stop conditions (described later) are met, the motion control unit 70 executes operation stop control, stopping the drive actuator 14 by controlling it to stop operation. This operation stop control is performed when it is necessary to stop the drive actuator 14. Here, "stopping the drive actuator 14" means stopping the operation of each power transmission component of the drive actuator 14. Here, the power transmission components refer to the components used to transmit the torque (power) generated by the prime mover 22 to the driven device 12, including the prime mover 22's drive shaft, the transmission 24's input shaft 40, the transmission mechanism 42, the output shaft 44, etc.

[0029] This operation stop control can be implemented, for example, by generating braking torque from the prime mover 22 to brake each power transmission component of the drive actuator 14. In this case, if an electric motor capable of generating regenerative braking is selected as the prime mover 22, regenerative energy can be generated simultaneously with the braking torque generated by the prime mover 22. Furthermore, if the drive actuator 14 is equipped with a braking device, the operation stop control can also be performed by generating braking torque from the braking device. Alternatively, the operation stop control can also be performed without relying on the prime mover 22 or the braking device to generate braking torque, by waiting for each power transmission component of the drive actuator 14 to stop naturally.

[0030] When the operation stop control is required to stop the drive actuator 14, the motion control unit 70 performs gear ratio change control in the transmission actuator 26 to change the actual gear ratio of the transmission 24 to a preset gear ratio. In this gear ratio change control, the motion control unit 70 changes the actual gear ratio to the preset gear ratio set by the setting unit 72. At this time, the motion control unit 70 reads the preset gear ratio stored in the storage unit 74 by the setting unit 72 and changes the actual gear ratio to the read preset gear ratio.

[0031] In this gear ratio change control, the motion control unit 70 changes the actual gear ratio of the transmission 24 during its operation, specifically, at least during the operation of the input shaft 40 and the transmission mechanism 42 of the transmission 24. After completing the change of the actual gear ratio of the transmission 24 based on the gear ratio change control, the operation of each power transmission component of the drive actuator 14 is stopped 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 if the input shaft 40 and the transmission mechanism 42 of the transmission 24 are not in operation. Thus, when performing gear ratio change control during the operation of the transmission 24, the gear ratio change control can be performed as long as the rotation detector (not shown) detects that the input shaft 40 of the transmission 24 or the prime mover 22 is rotating.

[0032] When the power transmission components of the drive actuator 14 stop operating, that is, when the drive actuator 14 stops operating, the motion control unit 70 completes the operation stop control. The stoppage of the power transmission components of the drive actuator 14 can be detected by a rotation detector (not shown) to determine that the drive actuator 14 has stopped operating. When the drive actuator 14 stops operating, the motion control unit 70 can stop supplying power to the electrical equipment (prime mover 22, speed changer 26, etc.) used in the drive actuator 14. As a result, each electrical device enters a non-powered state.

[0033] Before explaining the gear ratio set by the setting unit 72, the underlying concept will be explained. When the actual gear ratio of the transmission 24 is set to 0 or a value infinitely close to 0, the output side (output shaft 44) of the transmission 24, along with the driven device 12, enters a locked state (self-locking state) where rotation is restricted. This locked state means that it is difficult to rotate the transmission 24 from the output side, that is, it is difficult to rotate the driven device 12 (the rotation drive unit 12a of the driven device 12). At this time, although the input side (input shaft 40) of the transmission 24 can be rotated, the output side of the transmission 24 cannot be rotated at all or can hardly be rotated because the actual gear ratio is very small. In contrast, if the actual gear ratio of the transmission 24 is set to a value far from 0, the output side of the transmission 24, along with the driven device 12, will be in a rotation-allowed state where rotation is permitted.

[0034] The setting unit 72 variably sets the gear ratio used for the gear ratio change control described above. The gear ratio is set to a variable value that can be changed. When setting the gear ratio, the setting unit 72 stores the set gear ratio value in the storage unit 74. As the gear ratio, the setting unit 72 can set either one of the following two gear ratios: a locking gear ratio predetermined as a gear ratio of the transmission 24 used to lock the rotation of the driven device 12, and a rotation-allowing gear ratio predetermined as a gear ratio used to allow the driven device 12 to rotate. The locking gear ratio refers to the gear ratio that, by locking the rotation of the driven device 12, achieves the above-mentioned locked state, and is predetermined. Similarly, the rotation-allowing gear ratio refers to the gear ratio that, by allowing the driven device 12 to rotate, achieves the above-mentioned rotation-allowing state, and is predetermined. For example, the locking gear ratio is set within the range of zero (=1 / ∞) to several thousandths of a gear ratio, while the rotational allowable gear ratio is set within the range of 1 / 200 to several tens of a gear ratio. The gear ratio ranges listed here are only examples, and other gear ratio ranges can also be set.

[0035] The setting unit 72 can set the gear ratio according to instructions from a user or an external controller. Here, the external controller refers, for example, a host controller that centrally controls the operations of multiple drive actuators 14. When setting the gear ratio according to user specifications, the drive actuator 14 may also have a first operation unit that outputs the specified gear ratio as a user instruction to the control device 16 through user operation. In this case, the setting unit 72 simply sets the specified gear ratio output from the first operation unit to the set gear ratio. The first operation unit may be, for example, a switch or similar component mounted on a control panel, or an information processing terminal such as a touch panel.

[0036] Within the predetermined range of allowable rotational gear ratios, which is the range of gear ratios used to allow the driven device 12 to rotate as described above, the setting unit 72 can continuously or incrementally change the set gear ratio. In this embodiment, the setting unit 72 can set the set gear ratio to a locked gear ratio, or it can set the set gear ratio to any one of a plurality of allowable rotational gear ratios. This range of allowable rotational gear ratios can, for example, be a range from 1 / 200 to a fraction of a gear ratio as described above.

[0037] When the setting unit 72 sets the locked gear ratio to the set gear ratio, the motion control unit 70 changes the actual gear ratio of the transmission 24 to the locked gear ratio in the gear ratio change control. Therefore, when the drive actuator 14 is in a stopped state, it can achieve a locked state where the rotation of the driven device 12 is locked. In this case, the motion control unit 70 can change the actual gear ratio of the transmission 24 from the locked gear ratio to the rotationally permissible gear ratio via the gear shift actuator 26 after the drive actuator 14 starts running and before the drive of the driven device 12 begins.

[0038] When the rotational allowable gear ratio is set to the set gear ratio by the setting unit 72, the motion control unit 70 changes the actual gear ratio of the transmission 24 to the rotational allowable gear ratio in the gear ratio change control. As a result, when the drive actuator 14 is in the running stop state, it can be in a rotational allowable state that allows the driven device 12 to rotate.

[0039] The effects of the control device 16 described above will be explained. When the operation control unit 70 of the control device 16 intends to stop the drive actuator 14, it performs gear ratio change control via the gear shift actuator 26 to change the actual gear ratio of the transmission 24 to a set gear ratio. Therefore, regardless of the actual gear ratio used just before the drive actuator 14 stops operating, the actual gear ratio when the drive actuator 14 is in a stopped state can be set to the set gear ratio. Thus, when the drive actuator 14 is in a stopped state, changes in the degree of rotational suppression of the driven device 12 by the transmission 24 can be suppressed.

[0040] Assuming that when the drive actuator 14 is in a stopped state, in order to lock the rotation of the driven device 12, consider using a non-excited actuation type brake to brake the power transmission component of the drive actuator 14. In this case, there is a problem: to release the non-excited actuation type brake, it is necessary to continuously supply power to the non-excited actuation type brake, which will lead to increased energy consumption and heat generation. Regarding this, the motion control unit 70 of this embodiment can change the actual gear ratio of the transmission 24 to the locked gear ratio through gear ratio change control. Therefore, when the drive actuator 14 is in a stopped state, the actual gear ratio of the transmission 24 is changed to the locked gear ratio in advance through gear ratio change control, thereby locking the rotation of the driven device 12 through the transmission 24. Furthermore, if it is necessary to release the lock of the transmission 24, it is only necessary to change the actual gear ratio of the transmission 24 through the transmission actuator 26, without the need for continuous power supply as in the case of using a non-excited actuation type brake. Therefore, it can effectively solve problems such as increased energy consumption and heat generation, and can lock the rotation of the driven device 12 when the operation is stopped.

[0041] The control device 16 includes a setting unit 72 that can variably set the set gear ratio. Therefore, by changing the set gear ratio set by the setting unit 72, the degree of suppression of rotation of the driven device 12 by the transmission 24 when the drive actuator 14 is in a stopped state can be adjusted. Thus, the actual degree of rotation suppression can be adjusted according to the required degree of rotation suppression of the driven device 12, thereby improving the operational flexibility of the drive actuator 14.

[0042] The setting unit 72, acting as a setting gear ratio, can selectively set either a locking gear ratio for locking the rotation of the driven device 12 or a rotation-allowing gear ratio for allowing that rotation. Therefore, by setting either the locking gear ratio or the rotation-allowing gear ratio as the setting gear ratio, when the drive actuator 14 is in a stopped state, either the locked state or the rotation-allowing state can be selected as the state of the driven device 12. This further improves the operational flexibility of the drive actuator 14.

[0043] Assuming that, in order to select either the locked state or the rotation-allowed state as the state of the driven device 12, a solution through hardware modification can also be considered. Here, hardware modification refers to whether the electromagnetic brake is assembled into the drive actuator 14, thereby achieving function switching. In this regard, this embodiment has the following advantages: without modifying the hardware, only changing the set gear ratio, it is possible to select either the locked state or the rotation-allowed state as the state of the driven device 12.

[0044] The setting unit 72 can change the set gear ratio in stages or continuously within a predetermined range of allowable gear ratios that allow rotation of the driven device 12. Therefore, when the drive actuator 14 is in a stopped state, it is possible to allow rotation of the driven device 12 while adjusting the degree of rotational suppression of the driven device by the transmission 24. Furthermore, this further improves the operational flexibility of the drive actuator.

[0045] Next, the above-mentioned conditions for stopping operation will be explained. The conditions for stopping operation are, for example, (1) receiving a stop operation command from the user or external controller; (2) an abnormality occurs in the main power supply 18, etc.

[0046] When a stop command is received from the user in (1), the drive actuator 14 may have a second operation unit for outputting the stop command to the control device 16 according to the user's operation. This second operation unit may consist, for example, a switch on the control panel or an information processing terminal such as a touch panel. The switch may be a power switch that toggles whether power is supplied to the drive actuator 14. In this case, the second operation unit may also output the stop command to the control device 16 by performing a shut-off operation to stop the power supply. When the conditions in (1) are met, the motion control unit 70 may also use power supplied from the main power supply 18 to operate the various electrical devices (prime mover 22, speed change actuator 26, etc.) used by the drive actuator 14 when performing the aforementioned stop control and gear ratio change control. Alternatively, the motion control unit 70 may also use power supplied from the auxiliary power supply 20 to operate the various electrical devices.

[0047] (2) will be explained. An anomaly detector 80 for detecting anomalies in the main power supply 18 is provided outside the drive actuator 14. When the anomaly detector 80 detects an anomaly in the main power supply 18, it outputs an anomaly detection signal indicating the situation to the control device 16. Here, anomaly refers to an anomaly 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 decrease in the voltage of the power supplied from the main power supply 18, or an abnormal increase in the voltage. The anomaly detector 80 can use various detection methods, including known methods, to detect an anomaly in the main power supply 18. For example, it can detect an anomaly in the main power supply 18 caused by an abnormal increase in voltage when the voltage value of the power supplied from the main power supply 18 is above a predetermined allowable value.

[0048] If the motion control unit 70 of the control device 16 does not receive an abnormality detection signal from the abnormality detector 80, that is, when the main power supply 18 is not abnormal, the drive actuator 14 is driven by the power supplied from the main power supply 18. At this time, the various electrical devices (prime mover 22, speed change actuator 26, etc.) mounted in the drive actuator 14 are operated by using the power supplied from the main power supply 18, thereby realizing the operation of the drive actuator 14. Conversely, if the motion control unit 70 receives an abnormality detection signal output from the abnormality detector 80 during the operation of the drive actuator 14, the aforementioned operation stop control and speed ratio change control are executed by using the power supplied from the auxiliary power supply 20. At this time, the various electrical devices are driven by using the power supplied from the auxiliary power supply 20, thereby executing operation stop control, etc. If an abnormality detection signal is received during the operation of the drive actuator 14, the power supply used in the drive actuator 14 is switched from the main power supply 18 to the auxiliary power supply 20. Therefore, even if the main power supply 18 malfunctions, the operation control unit 70 of the control device 16 can still use the power supplied from the auxiliary power supply 20 to perform gear ratio change control, so that the drive actuator 14 switches to the running stop state.

[0049] Next, the features of the speed change actuator 26 will be described. (See reference) 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 the gear ratio changing mechanism 46 through which the power output from the output unit 26c is input to the gear ratio changing mechanism 46 of the transmission 24.

[0050] In this embodiment, the power source 26a is a motor that generates rotational power. The transmission mechanism 26b of this embodiment employs a lead screw mechanism, which includes: a lead screw shaft 26d driven to rotate by the power source 26a, and a ball nut 26e capable of linearly moving with the rotation of the lead screw shaft 26d. A helical first threaded groove (not shown) is formed on the outer circumferential surface of the lead screw shaft 26d, and a helical second threaded groove (not shown) is formed on the inner circumferential surface of the ball nut 26e. The balls are disposed in the helical space surrounded by the first and second threaded grooves. In this embodiment, the output section 26c is a moving body capable of linearly moving integrally with the ball nut 26e of the transmission mechanism 26b.

[0051] The transmission mechanism 26b has a self-locking function: it allows power to be transmitted from the input side (power source 26a) to the output side (output section 26c), while restricting the transmission of power from the output side to the input side. To achieve this, when the power source 26a generates rotational power, the feed screw mechanism composed of the transmission mechanism 26b converts this rotational power into linear power for the ball nut 26e through the rotation of the screw shaft 26d accompanying the rolling of the balls, and transmits the converted linear power to the output section 26c. Thus, power can be transmitted from the input side to the output side. Conversely, when the linear power is transmitted from the output section 26c to the ball nut 26e, the contact between the ball nut 26e and the threaded groove of the screw shaft 26d with the balls in the helical space restricts the movement of the screw shaft 26d caused by this linear power, and restricts the transmission of this linear power to the power source 26a. Thus, the self-locking function restricts the transmission of power from the output side to the input side. This self-locking function can also be achieved when the variable speed actuator 26 is in a non-powered state without being supplied with power.

[0052] This self-locking function allows the transmission 24 to change its actual gear ratio when a change is needed. Power generated by the power source 26a, which consumes electricity, can be transmitted from the input side to the output side, thus changing the actual gear ratio. Furthermore, during the operation of the drive actuator 14, a force is generated that attempts to change the actual gear ratio of the transmission 24. This force could potentially transmit power from the output side to the input side of the transmission actuator 26. In this case, the self-locking function of the transmission actuator restricts the transmission of power from the output side to the input side, thereby maintaining the actual gear ratio of the transmission 24 even when no power is supplied to the transmission actuator 26. Therefore, compared to continuously supplying power to the transmission actuator 26 to maintain the actual gear ratio of the transmission 24, the energy consumption and heat generation of the transmission actuator 26 can be reduced, thereby improving energy efficiency.

[0053] The specific structure of the transmission mechanism 26b that enables the self-locking function is not particularly limited. For example, a combination of a worm gear and a worm wheel, which is known to have this self-locking function, can be used. Furthermore, the speed change actuator 26 may not have a transmission mechanism 26b with a self-locking function. In this case, the speed change actuator 26 may be constructed using an electromagnetic solenoid or the like, for example, instead of a feed screw mechanism.

[0054] (Second Embodiment) Next, refer to Figure 4 Another application example of the actuator unit will be described. Here, an example of the actuator unit being used in robot 90 is shown. The robot 90 in this embodiment is a collaborative robot capable of working in conjunction with humans, but its specific example is not particularly limited and can be various industrial robots or service robots.

[0055] The robot 90 of this embodiment is a multi-joint robot with 6 joints. This number of joints is not particularly limited and can be any number from 2 to 5, or 7 or more. The robot 90 includes multiple joints 92A to 92F and multiple robot parts 94A to 94G connected in series by the multiple joints 92A to 92F. In the robot 90, the robot part 94A at the base end becomes a base part, and the robot parts 94B to 94G further forward become arm parts. A gripper or other attachment 96 is detachably mounted on the robot part 94G (arm part) at the foremost end.

[0056] The robot 90 includes actuator units 10A to 10F assembled at each joint 92A to 92F and driving the joints 92A to 92F. Here, "driving the joint" means rotating (changing the relative position) the front-end arm member relative to the base-end arm member connected by joints 92A to 92F. In this case, the driven device 12 becomes the front-end arm member connected by joints 92A to 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 assembled at these joints. Here, the base-end first joint 92A and the front-end sixth joint 92F can rotate about a vertical axis, while the other joints 92B to 92E can rotate about a horizontal axis.

[0057] Each actuator unit 10A to 10F has the same structure as the actuator unit in the first embodiment. The setting section 72 of the control device 16 of each actuator unit 10A to 10F can independently set the setting gear ratio. For example, the control device 16 of the first actuator unit 10A can set the locking gear ratio to the setting gear ratio, and the control device 16 of the second actuator unit 10B can set the rotational allowable gear ratio to the setting gear ratio.

[0058] Therefore, when the actuator units 10A to 10F used by the robot 90 are in a stopped state, the rotational suppression degree of each joint 92A to 92F can be changed by altering the set gear ratio of each actuator unit 10A to 10F corresponding to each joint 92A to 92F. Thus, compared to using the same rotational suppression degree for all joints 92A to 92F, the operational flexibility of the robot 90 can be improved. For example, consider the following situation: only the actuator units 10A and 10F used in joints 92A and 92F, which can rotate around the vertical axis, are set to locked gear ratios, while the actuator units 10B to 10E used in the remaining joints 92B to 92E are set to rotationally permissible gear ratios. In this case, it is possible to prevent the joints 92A and 92F of the robot 90 from rotating around the vertical axis while allowing position adjustments using other joints 92B to 92E. Furthermore, if the actuator unit 10 used in the joints 92B to 92E of the robot 90, which are capable of rotating around the horizontal axis, is set to a locked gear ratio, it also has the advantage of being able to suppress the sagging of the joint caused by its own weight rotating around the horizontal axis.

[0059] Furthermore, compared to industrial robots primarily used for simple tasks in manufacturing, collaborative robots are widely used in various industries such as food, logistics, and catering. Therefore, they often operate closer to humans and require greater operational flexibility compared to industrial robots used for simple tasks. As mentioned above, the increased operational flexibility is an advantage when using collaborative robots.

[0060] The variations of the above embodiments will be described. The setting unit 72 of the control device 16 can also set the setting gear ratio invariably. In this case, the setting gear ratio is set to a fixed value that cannot be changed. Thus far, an example has been described where the setting unit 72 can set either the locking gear ratio or the rotational allowable gear ratio as the setting gear ratio when the setting gear ratio is variable. Furthermore, when the setting unit 72 sets the setting gear ratio variable, it may not set the locking gear ratio as the setting gear ratio, but can set the setting gear ratio in stages or continuously only within the rotational allowable gear ratio range.

[0061] The above embodiments and variations are examples. The abstracted technical concepts should not be interpreted as being limited to the contents of the embodiments. The contents of the embodiments can undergo many design changes, such as alterations, additions, and deletions of constituent elements. In the above embodiments, the description "embodiment" is used to emphasize that such design changes are permitted. However, even without this description, design changes are still permitted. The shaded lines on the cross-sections of the drawings do not limit the material of the objects marked with shaded lines. Furthermore, any solution obtained by substituting any of the constituent elements and descriptions of the present invention among methods, apparatuses, systems, etc., is valid as an embodiment of the present invention.

[0062] Industrial availability This invention relates to a control device for driving actuators.

[0063] Symbol Explanation 10-Actuator unit, 10A-First actuator unit, 10B-Second actuator unit, 12-Driven device, 14-Drive actuator, 16-Control device, 18-Main power supply, 20-Auxiliary power supply, 22-Prime mover, 24-Gearbox, 26-Speed-changing actuator, 70-Motion control unit, 72-Setting unit, 90-Robot, 92A-First joint, 92B-Second joint.

Claims

1. A control device comprising an action control unit that controls the action of a drive actuator, the drive actuator comprising: a prime mover; a gearbox that outputs rotational input from the prime mover to a driven device after speed change; and a speed-changing actuator capable of changing the actual gear ratio of the gearbox. When the motion control unit wants to stop the drive actuator, it performs gear ratio change control: by changing the actual gear ratio to a preset gear ratio through the gear actuator.

2. The control device according to claim 1, wherein, When the motion control unit performs the gear ratio change control, it changes the actual gear ratio to the locked gear ratio; the locked gear ratio is a gear ratio that is set as the set gear ratio and is predetermined in order to lock the rotation of the driven device.

3. The control device according to claim 1 or 2, wherein, The control device includes a setting unit that can variably set the set gear ratio.

4. The control device according to claim 3, wherein, The setting unit can set either a locking gear ratio predetermined for locking the rotation of the driven device, or a rotation-allowing gear ratio predetermined for allowing the rotation of the driven device, as the setting gear ratio.

5. The control device according to claim 3 or 4, wherein, The setting unit can change the set gear ratio in stages or continuously within the rotational allowable gear ratio range, which is predetermined as a gear 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 anomaly occurs in the main power supply that supplies power to the drive actuator, the motion control unit uses power supplied from the auxiliary power supply to perform the gear ratio change control.

7. An actuator unit comprising: 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 variable speed actuator has a self-locking function, which allows power to be transmitted from the input side to the output side and restricts power from being transmitted from the output side to the input side.

9. A robot that possesses: First joint; The first actuator unit is the actuator unit as described in claim 7 or 8, and the first actuator unit is assembled on the first joint. Second joint; and The second actuator unit, which is the actuator unit according to claim 7 or 8, is assembled on the second joint, wherein... The control devices assembled in the first actuator unit and the second actuator unit are capable of independently setting their respective set speed ratios.

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