JP2019047649A - Driving device and robot - Google Patents

Abstract

To provide a small-scaled lightweight driving device capable of obtaining large gripping force and of high-speed and high-accuracy driving of a holding part.SOLUTION: A driving device 1 comprises: a vibration type actuator 2; a motor shaft part 3a rotated by the vibration type actuator 2; an output shaft part 3b outputting rotational driving force generated by the motor shaft part 3a to outside; and a first power transmission system and a second power transmission system transmitting the rotational driving force generated by the motor shaft part 3a to the output shaft part 3b. The route for transmitting the rotational driving force generated by the motor shaft part 3a to the output shaft part 3b is switched between the first power transmission system and the second power transmission system in accordance with the torque generated by the rotative direction of the motor shaft part 3a and the vibration type actuator 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drive device of a hand device constituting an industrial robot or the like, and a robot including the drive device.

  As one of end effectors of industrial robots and the like, a hand device is used which holds a gripping target such as a part with a plurality of finger portions. Here, some hand devices perform a relatively simple movement in which two or three fingers slide to grip and hold an object to be gripped, such that an articulating finger wraps the object to be gripped A variety of structures are known up to what is gripped. In recent years, multifunctionalization of the hand device has been advanced, and for example, a device capable of reliably gripping a soft gripping object or a gripping object having a complicated shape has appeared. In addition, there has also appeared a device capable of grasping an object to be grasped having different sizes and weights dexterously without replacing a portion in contact with the object to be grasped in the hand device.

  With the multi-functionalization of such a hand device, more and more finger drive and wrist joints of the hand device are equipped with a larger number of drive devices than ever before. However, if the number of driving devices increases and the mass of the hand device increases, the operation performance of the industrial robot equipped with the hand device will deteriorate. Therefore, a driving device for driving the hand device is required to be small in size and light in weight and capable of generating a large torque.

  As an example, Patent Document 1 proposes a finger joint mechanism that realizes high torque and small drive system by combining a motor and a plurality of small wave gear reducers. Specifically, in the finger joint mechanism described in Patent Document 1, by using two small wave gear reducers, the installation space is increased as compared with the case where one large reducer is used. Increases the rate of increase in torque capacity to the rate. Further, Patent Document 1 describes that the use of a wave gear reducer having a small number of components as a reducer facilitates downsizing as compared with the case where other types of reducers are used.

Patent No. 4737695 gazette

  While the hand device is required to have a large gripping force, it is desirable to increase the operating speed to reduce the process time. That is, a mechanism capable of switching between low speed high torque drive and high speed low torque drive is required. However, although the finger joint mechanism described in Patent Document 1 is suitable for low-speed high-torque driving, it is not suitable for high-speed low-torque driving.

  As a configuration capable of switching between low-speed high-torque driving and high-speed low-torque driving, a new gear train having a relatively small reduction ratio may be provided in parallel to switch the gear train. However, such a configuration requires a brake device to obtain holding power at the time of drive stop, and also needs to arrange a new gear train so as to avoid a large-size wave gear reducer. Problems, and it is not easy to miniaturize the entire hand device.

  In addition, the hand device needs to have the ability to grip the object to be grasped after the grasping portion comes into contact with the object to be grasped with high accuracy. For example, in the case of gripping a ring-shaped part with a three-fingered grip from the outer peripheral side toward the center from the outer peripheral side, the ring-shaped part slides when time lag occurs at the moment each grip unit contacts the ring-shaped part It may be tilted and gripped with the center of gravity shifted. In this case, an error may occur due to an inability to perform alignment in a post-stage assembly operation, which may lower productivity. And, in the power transmission system via the reduction gear as described in Patent Document 1 mentioned above, it is said that the positional accuracy at the time when the contact of the grip portion with the object to be gripped is started is easily deteriorated due to the occurrence of backlash. There's a problem.

  Furthermore, in a gripping mechanism using a reduction gear having a large reduction ratio, since the moment of inertia is large, an error due to the inertial force is likely to occur in the gripping force when contact of the gripping portion with the gripping object starts. Management is difficult. In addition, there is also a problem that an error in torque control of the motor for driving the grip portion is amplified by the reduction ratio.

  An object of the present invention is to provide a small and lightweight drive device capable of obtaining a large gripping force and capable of high-speed drive and high-precision drive of a grip portion.

  The drive device according to the present invention includes a vibration type actuator, a motor shaft that rotates by driving the vibration type actuator, an output shaft that outputs the rotational driving force of the motor shaft to the outside, and the motor shaft. A first power transmission system and a second power transmission system for transmitting a rotational drive force to the output shaft, and the motor shaft according to the rotational direction of the motor shaft and the torque generated by the vibration-type actuator It is characterized in that a path through which the rotational driving force of the unit is transmitted to the output shaft unit is switched between the first power transmission system and the second power transmission system.

  According to the present invention, it is possible to realize a small and lightweight drive device capable of obtaining a large gripping force and capable of high-speed drive and high-precision drive of the grip portion.

It is a perspective view showing a schematic structure of a drive concerning an embodiment of the present invention. It is a top view of the drive device of FIG. It is a figure explaining the operation | movement pattern of the holding part of the drive device of FIG. It is a perspective view which shows schematic structure of a finger unit provided with the drive device of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. FIG. 1 is a perspective view showing a schematic configuration of a drive device 1 according to an embodiment of the present invention. FIG. 2 is a plan view of the drive device 1. The driving device 1 includes a vibration type actuator 2, a motor shaft 3a, an output shaft 3b, a drive shaft 4a, a driven shaft 4b, a torque limiter 5, a meshing clutch 6, a one-way clutch 7, a first gear 8 and a second gear. A gear 9 is provided.

  The motor shaft 3 a and the output shaft 3 b are coaxially disposed via the torque limiter 5. The drive shaft 4a and the driven shaft 4b are coaxially arranged, and the motor shaft 3a and the output shaft 3b, and the drive shaft 4a and the driven shaft 4b are arranged substantially parallel to each other. . The motor shaft portion 3 a penetrates the vibration type actuator 2 and is rotated by driving the vibration type actuator 2. The output shaft 3b outputs the rotation of the motor shaft 3a to the outside.

  The vibration type actuator 2 rotates a driven body and a vibrating body relative to each other by frictionally driving the driven body in contact with the vibrating body by exciting high frequency vibration to the vibrating body, and generates the generated rotational driving force. Is a type of rotary motor that takes out to the outside through the motor shaft 3a. Generally, the vibration-type actuator 2 is characterized in that the torque in the low speed region is large and the torque density is high (the torque per unit volume is large) as compared with the electromagnetic motor. In the present embodiment, as the vibration type actuator 2, for example, one having a cylindrical shape having an outer diameter of φ 15 and an axial length of 20 mm is preferable which can give a torque of 0.1 N · m or more. Used for Since the torque of the brushless DC motor of the same size is about 0.005 N · m, in terms of torque density, the configuration using the vibration type actuator 2 is more than the configuration using the brushless DC motor There is an advantage.

  The torque limiter 5 transmits the driving force by mechanical friction obtained by applying a spring force, and cuts off the driving force by friction slip when the torque exceeds a predetermined magnitude. In the torque range gripped by static friction, there is no problem even if it is considered that the rotation is transmitted without slipping, and the rotation of the motor shaft 3a is directly transmitted to the output shaft 3b. Ru.

  The output path of the rotational drive force of the vibration-type actuator 2 has two paths of a first power transmission system and a second power transmission system. The first power transmission system is a path that is directly output from the output shaft 3b via the torque limiter 5 from the motor shaft 3a. The second power transmission system is a path output through the motor shaft 3a, the first gear 8, the drive shaft 4a, the meshing clutch 6, the driven shaft 4b, the one-way clutch 7, the second gear 9, and the output shaft 3b. It is. The output shaft portion 3b is a portion common to the first power transmission system and the second power transmission system, and the grip portion (not shown) of the hand device is attached to the output shaft portion 3b.

  The first gear 8 has a first small gear portion 8a attached to the motor shaft portion 3a and a first large gear portion 8b attached to the drive shaft portion 4a. The second gear 9 has a second large gear portion 9a attached to the output shaft portion 3b and a second small gear portion 9b attached to the one-way clutch 7 disposed on the driven shaft portion 4b. The first small gear portion 8a and the first large gear portion 8b mesh with each other, and the second small gear portion 9b and the second large gear portion 9a mesh with each other, with the first gear 8 and the second gear 9 interposed therebetween. Thus, it is possible to transmit the driving force between the first power transmission system and the second power transmission system.

  The meshing clutch 6 is a clutch that couples the drive shaft 4a and the driven shaft 4b by mechanical meshing. In the present embodiment, as shown in FIG. 1, a jaw clutch is used in which the moving member 6a and the fixing member 6b are engaged with each other. In the meshing clutch 6, when the drive shaft 4a rotates in the direction of arrow CCW (counterclockwise) in FIG. 1 when the fixed member 6b is stopped or substantially stopped, the moving member 6a moves to the fixed member 6b side. The sliding member 6 a and the fixing member 6 b are engaged with each other. When the drive shaft 4a rotates in the direction of the arrow CW (clockwise) in FIG. 1, the moving member 6a slides toward the first large gear portion 8b, and the engagement with the fixing member 6b is released.

  The one-way clutch 7 transmits the driving force in one direction between the inner ring and the outer ring coaxially arranged, and even if the inner ring and the outer ring are rotating in the same direction, the angular velocity difference between them is Switch between connection and release. The inner ring of the one-way clutch 7 is integrated with the driven shaft 4b, and the outer ring of the one-way clutch 7 is integrated with the second small gear 9b. The connection and release of the one-way clutch 7 is determined according to the magnitude and the positive / negative of the angular velocity difference between the inner ring (follower shaft 4b) and the outer ring (second small gear portion 9b).

  Next, an operation pattern of the grip unit by the drive device 1 will be described. FIG. 3 is a diagram summarizing the operation of each part for each operation pattern of the gripping part. “Closed” of the movement pattern A refers to a movement that closes until the gripping portion contacts the gripping object to grip the gripping object. The “gripping” of the movement pattern B refers to an operation in which the movement pattern A for closing the holding portion is finished, and the torque for holding the object to be held is increased to hold the object to be held. The “open” of the movement pattern C refers to an opening movement for releasing the object to be held held by the holding unit. Note that “CW” and “CCW” in FIG. 3 correspond to the arrows CW and CCW shown in FIG. 1, respectively. That is, the clockwise rotation direction when the torque limiter 5 is viewed from the vibration type actuator 2 in FIG. 1 is CW, and the counterclockwise rotation direction is CCW.

  The operation patterns A to C of the grip portion are realized by a combination of the above-described connection / release states of the torque limiter 5, the meshing clutch 6 and the one-way clutch 7. That is, the connection / release of the torque limiter 5 according to the magnitude of the frictional force, the connection / release of the one-way clutch according to the magnitude and the positive / negative of the angular velocity difference, and the connection / release of the meshing clutch according to the rotational direction By switching, operation patterns A to C can be realized.

  First, the operation pattern A will be described. In the present embodiment, in order to perform the operation of closing the grip portion, the vibration type actuator 2 is driven so that the motor shaft portion 3a is rotated in the CW direction. In the operation pattern A, the rotational drive force generated by the vibration type actuator 2 is directly output from the output shaft 3b through the first power transmission system (motor shaft 3a and torque limiter 5), and the second power transmission system is idle. Do. More specifically, at the time of execution of the operation pattern A, the grip portion is not in contact with the grip target object, and no grip force is generated in the grip portion. Therefore, in the torque limiter 5, the motor shaft portion 3a is output by static friction force It is in a state of being connected to the shaft 3b. As a result, the rotation of the motor shaft 3a is directly transmitted to the output shaft 3b.

  When the motor shaft portion 3a rotates in the CW direction, the first small gear portion 8a of the first gear 8 attached to the motor shaft portion 3a rotates in the CW direction, and the first large gear meshes with the first small gear portion 8a. The gear portion 8 b is decelerated in rotational speed and rotates in the CCW direction. In the meshing clutch 6, as described above, the movable member 6a slides toward the fixed member 6b by rotation in the CCW direction and engages with the fixed member 6b, whereby the drive shaft 4a, the driven shaft 4b and the one-way clutch The inner ring of 7 rotates integrally in the CCW direction. Here, the second large gear portion 9a of the second gear 9 rotates in the CW direction together with the output shaft portion 3b, and the second small gear portion 9b meshing with the second large gear portion 9a is accelerated to CCW. Rotate in the direction. Therefore, in the one-way clutch 7, both the inner ring and the outer ring rotate in the CCW direction. At this time, the angular velocity of the outer ring of the one-way clutch 7 integrated with the second small gear portion 9 b is larger than the angular velocity of the inner ring of the one-way clutch 7. Therefore, in the one-way clutch 7, the outer ring rotates in the CCW direction relative to the inner ring (referred to as "outside CCW" in FIG. 3), and the second power transmission system slips.

  Subsequently, the operation pattern B will be described. In the operation pattern B, the rotational driving force generated by the vibration type actuator 2 is not output to the output shaft portion 3b through the first power transmission system due to the torque limiter 5 slipping, and torque amplification is performed through the second power transmission system. And then output from the output shaft 3b. Specifically, the vibration type actuator 2 is driven so that the motor shaft portion 3a rotates in the CW direction, and the operation pattern A is executed, whereby the grip portion grips the grip target object (the grip portion is a grip target object And the output shaft 3b can not rotate any more. Thus, the rotation of the output shaft portion 3b is suppressed, and the output torque of the vibration-type actuator 2 starts to increase. When the output torque of the vibration-type actuator 2 exceeds the limit of the torque limiter 5, no more torque is transmitted, and the torque limiter 5 slips.

  On the other hand, the first large gear portion 8b meshing with the first small gear portion 8a attached to the motor shaft portion 3a has a low rotational speed, but its torque is amplified and rotates in the CCW direction. Further, since the meshing clutch 6 is maintained in the engaged state between the moving member 6a and the fixed member 6b by the rotation in the CCW direction following the operation pattern A, the drive shaft 4a, the driven shaft 4b and the one-way clutch The inner ring of 7 rotates integrally in the CCW direction. At this time, due to the idling of the torque limiter 5, the rotational driving force via the second gear 9 is not transmitted to the outer ring of the one-way clutch 7. Therefore, the outer ring of the one-way clutch 7 rotates relative to the inner ring in the CW direction (referred to as "outside CW" in FIG. 3), and the one-way clutch 7 is switched to the connected state. The outer ring rotates in the CCW direction. When the outer ring of the one-way clutch 7 rotates in the CCW direction, the second small gear portion 9b integral with the outer ring rotates in the CCW direction, and the second large gear portion engaged with the second small gear portion 9b. 9a rotates in the CW direction, that is, in the same direction as the rotation direction of the motor shaft 3a. Strictly speaking, a very small distance (angle) of rotation occurs between the release of the torque limiter 5 and the release of the one-way clutch 7 after the release of the torque limiter 5, and then the second power transmission system The torque transmission to the output shaft 3b is started. The torque generated by the vibration-type actuator 2 is determined by each of the first small gear portion 8 a and the first large gear portion 8 b in the first gear 8 and the second small gear portion 9 b and the second large gear portion 9 a of the second gear 9. It is amplified by the reduction ratio determined by the gear ratio, transmitted to the output shaft 3b, and becomes the gripping force of the gripping portion.

  Subsequently, the operation pattern C will be described. In the operation pattern C, the rotational driving force generated by the vibration type actuator 2 is directly output from the output shaft 3b through the first power transmission system (through the motor shaft 3a and the torque limiter 5), and the second power transmission system Idle. More specifically, in the present embodiment, in order to perform the opening operation of the grip portion, the vibration-type actuator 2 is driven such that the motor shaft portion 3a rotates in the CCW direction. At this time, since the grip portion moves away from the object to be gripped, no torque is applied to the torque limiter 5, and the torque limiter 5 is in the connected state. That is, in the torque limiter 5, the motor shaft 3a is connected to the output shaft 3b by static friction, and the rotation of the motor shaft 3a is directly transmitted to the output shaft 3b and the output shaft 3b is Rotate in CCW direction.

  As a result, the second large gear portion 9a of the second gear 9 rotates in the CCW direction together with the output shaft portion 3b, and the second small gear portion 9b meshing with the second large gear portion 9a is accelerated in the CW direction. Rotate. Thus, in the one-way clutch 7, the outer ring rotates in the CW direction relative to the inner ring (referred to as "outside CW" in FIG. 3), which is in a connected state. However, when the motor shaft portion 3a rotates in the CCW direction, the first small gear portion 8a of the first gear 8 attached to the motor shaft portion 3a rotates in the CCW direction and meshes with the first small gear portion 8a. The large gear portion 8b rotates in the CW direction. As described above, in the meshing clutch 6, the movable member 6a is separated from the fixed member 6b and is released by the rotation in the CW direction, so that the second power transmission system slips.

  Next, space saving of the drive device 1 will be described. The vibration type actuator 2 can take out an output (rotational driving force) from both ends of the motor shaft 3a. Therefore, in the driving device 1, the first small gear portion 8a is provided at a position opposite to the output shaft portion 3b with respect to the vibration type actuator 2 in the motor shaft portion 3a, and the first small gear portion 8a is By meshing with the gear portion 8b, an output is taken out to the second power transmission system. As a result, since the meshing clutch 6 and the one-way clutch 7 can be arranged side by side with the vibration-type actuator 2, the axial length of the entire drive device 1 can be shortened.

  The arrangement of the meshing clutch 6 and the one-way clutch 7 with respect to the vibration type actuator 2 is made possible by using the vibration type actuator 2 with high torque density, and the reason will be described below. As described above, for example, as the vibration-type actuator 2, one having an outer diameter of φ15 and an axial length of 20 mm and capable of generating a torque of 0.1 N · m or more is suitably used. . Assuming that the numbers of teeth of the first small gear portion 8a and the first large gear portion 8b are 25 and 60, and the numbers of teeth of the second large gear portion 9a and the second small gear portion 9b are 65 and 20, respectively. The reduction ratio is 7.8, and a torque of 0.78 N · m or more can be extracted from the output shaft portion 3b in calculation. For example, when the driving device 1 is disposed in each gripping portion of each finger in a three-fingered hand apparatus, a gripping force (torque) of 2 N · m or more can be obtained, and thus the driving device 1 drives the gripping portions It can be determined that the power source can be used sufficiently. Therefore, it is not necessary to use a reduction gear having a relatively large size such as a wave gear reduction gear having a high reduction ratio or a planetary gear reduction gear, and a compact configuration can be realized.

  Further, inside the vibration type actuator 2, a vibrator and a driven body (not shown) are in constant contact with a constant pressing force, and this pressing force is a relative position between the vibrating body and the driven body. To create a holding force to hold the Therefore, regardless of which path of the first power transmission system and the second power transmission system the output of the vibration actuator 2 is transmitted before the driving stop of the vibration actuator 2, the vibration actuator 2 after the stop When no current is supplied, the holding force suppresses the rotation of the motor shaft 3a. That is, the holding force generated inside the vibration-type actuator 2 resists the external force and the gravity applied to the drive device 1 and suppresses the rotation of each component constituting the drive device 1. Therefore, in the drive device 1, there is no need to separately provide a brake or the like for maintaining the output shaft portion 3 b in a stationary state, and therefore, downsizing and weight reduction are possible.

  Next, a finger unit of a hand device will be described as a specific example of a robot using the drive device 1. FIG. 4 is a perspective view showing a schematic configuration of the finger unit 20. As shown in FIG. The hand device (not shown) includes, for example, a plurality of (e.g., three) finger units 20, and the three finger units 20 grip a gripping target. The finger unit 20 has a fixing portion 25, a finger portion 22 and a gripping portion 24. A finger joint is provided between the fixed portion 25 and the finger portion 22. A finger joint is provided between the finger portion 22 and the grip portion 24. The grip joint is provided between the finger portion 22 and the grip portion 24. Is provided.

  The fixing portion 25 is a part of the main body corresponding to the palm of the hand device or a portion integrally mounted on the main body. A finger drive unit 27 a is installed in the fixed unit 25, and a grip unit drive unit 27 b is installed in the finger unit 22. The finger drive unit 27a and the grip unit drive unit 27b are respectively equivalent to the drive unit 1 shown in FIG. The finger rotation shaft 21 is the output shaft 3b of the finger drive device 27a. That is, in the finger joint, the output shaft 3b of the finger driving device 27a is inserted into the hole provided in the connecting portion 26 of the finger 22 and functions as the finger rotation shaft 21, and the finger driving device 27a The generated driving force is directly transmitted to the finger portion 22. On the other hand, in the gripping joint, the output shaft portion 3b of the gripping portion drive device 27b is connected to the gripping portion rotation shaft 23 disposed substantially orthogonal to the output shaft portion 3b via a bevel gear (not shown) The rotation of the output shaft 3b is converted to the rotation of the grip rotation shaft 23 via a bevel gear.

  In an assembly process of a predetermined product by a hand device at a production site, it is important that the hand device grips a gripping target (part) with high accuracy. The operation of grasping the object to be grasped here corresponds to the operation pattern A (closed) described with reference to FIG. The operation pattern A includes a preparation phase in which the gripping unit 24 is moved quickly to the start position of the gripping operation, and an approaching phase in which the gripping unit 24 is brought close to and comes into contact with the gripping object while performing precise position control of the gripping unit 24 Can be divided into In the preparation phase, the shape and the position of the object to be grasped are detected by predetermined sensing means, and the grasping portion 24 is moved quickly (at high speed) to the start point of the grasping operation based on the detection result. At this time, both the finger drive unit 27a and the grip unit drive unit 27b are driven, but both are drive in a no-load state where no gripping force is generated. Therefore, the rotational drive force of the vibration-type actuator 2 of each of the finger drive 27a and the grip drive 27b is output from the output shaft 3b through the first power transmission system. Thus, the finger 22 is rotated at high speed around the finger rotation axis 21 and the grip 24 is rotated at high speed around the grip rotation axis 23 to move the grip 24 to the start point of the gripping operation. Can.

  In the approach phase, the gripper 24 moved to the start point in the preparation phase is moved toward the object to be grasped at a slower speed than the preparation phase. At this time, the plurality of gripping portions 24 must be brought close to the same gripping object simultaneously, and contact with the gripping object must be started almost simultaneously. Therefore, the driving of the grip driving device 27b via the bevel gear that may cause backlash is stopped, and only the finger driving device 27a capable of direct driving is driven. As a result, the gripping portions 24 can be moved while being controlled with higher precision than in the preparation phase, and contact with the gripping objects of the plurality of gripping portions 24 can be started substantially simultaneously. As a result, the gripping operation of the object to be grasped can be completed without causing a disadvantage such as displacement of the center of gravity of the object to be grasped.

  After completion of the operation pattern A, an operation to increase the gripping force of the gripping portion 24 is started. The operation for increasing the gripping force here corresponds to the operation pattern B (gripping) described with reference to FIG. The movement pattern B starts from the time when a holding force is generated by the holding unit 24 contacting the holding object in the movement pattern A. If the drive system has a reduction gear with a high reduction ratio, and the moment of inertia of the entire drive system is large, an error in the gripping force due to the inertia occurs at the initial stage of contact between the object to be gripped and the gripping portion It will be easier. On the other hand, in the hand device constituted by the finger unit 20, since the finger 22 is directly driven around the finger rotation shaft 21 by the drive of the finger drive 27a, the moment of inertia of the entire drive system is reduced. This makes it possible to reduce the gripping force error at the initial stage of contact. And when controlling the grasping power of a plurality of finger units 20, the error of the initial stage of contact becomes small, and it is possible to grasp the grasped object with good balance, and the control of the grasping power thereafter is easy and highly accurate It can be carried out.

  The increase of the gripping force is performed by switching the output from the vibration type actuator 2 of each of the finger drive 27a and the grip drive 27b from the first power transmission system to the second power transmission system. The driving device 1 (the finger portion driving device 27a and the gripping portion driving device 27b) includes the transmission system having a relatively small reduction ratio because the vibration type actuator 2 with high torque density is used. Therefore, even if the torque error is amplified by the reduction ratio by the torque control method inherent to the vibration-type actuator 2, it does not become a large error, and hence the gripping force can be controlled with high accuracy. In addition, according to the magnitude | size of the holding | grip force calculated | required, you may perform increase of a holding | grip force by driving only any one of the finger part drive 27a and the holding part drive 27b.

  The hand device is generally driven to move the object to be gripped to another location, but if the gripping force between the hand device is sufficient, the finger drive device 27a and the gripper drive may be used. The power supply to each vibration type actuator 2 of the device 27b may be stopped. That is, in the hand apparatus including the finger unit 20, a driving method can be used which maintains the gripping object by the holding force of the vibration type actuator 2 of each of the finger driving device 27a and the gripping unit driving device 27b. . This allows the finger joint and the grip joint to be fixed by the holding force of the vibration type actuator 2 even if power supply to the vibration type actuator 2 is stopped, so that the gripping object can be maintained It is from.

  A state in which a large torque is output through the second power transmission system by the operation pattern B (gripping) immediately before stopping the power supply to the vibration type actuator 2 of each of the finger driving device 27a and the gripping unit driving device 27b. It has become. Therefore, even if the power supply to the vibration-type actuator 2 is stopped, the grasped object is maintained in the grasped state with a constant grasping force. In this way, when the driving method for stopping the power supply to the vibration-type actuator 2 and maintaining the gripped object is adopted, the power supply to the vibration-type actuator 2 is performed only when the finger unit 20 is opened and closed and when the gripping force is adjusted. Power saving can be achieved because it is sufficient.

  After the object to be grasped held by the finger unit 20 is moved to a predetermined position by driving the main body of the hand apparatus, etc., the operation of the operation pattern C (open) in FIG. 3 at the predetermined position of the movement destination As a result, the gripping object is released. After the object to be gripped and the finger unit 20 are not in contact with each other, power supply to the vibration type actuator 2 of each of the finger drive 27a and the grip drive 27b is stopped, and the holding force of the vibration type actuator 2 is The finger unit 20 can be maintained stationary by utilizing it. At that time, the finger unit 20 can be kept stationary by the holding force whose upper limit is the allowable maximum torque of the torque limiter 5.

  Thus, in the hand apparatus using the finger unit 20, the holding force of the vibration type actuator 2 of each of the finger drive unit 27a and the holding unit drive unit 27b can be used for the holding force generated by the finger unit 20. . At that time, a driving method for obtaining necessary gripping force while supplying power to the vibration type actuator 2 and a driving method using the holding power generated inside the vibration type actuator 2 by stopping the power supply to the vibration type actuator 2 And can be used selectively. Then, in the state where the finger unit 20 grips the object to be gripped, each indirect part of the finger unit 20 can be fixed with a large holding force, so even if an impact is applied to the finger unit 20 by the action of external force or the like. , It is difficult to drop the gripped object. On the other hand, when the finger unit 20 does not grip the object to be gripped, the indirect part of the finger unit 20 can be fixed with a small holding force, so that even if an external force acts, the finger unit moves in the direction to release the external force 20 slips. As a result, it is possible to suppress the failure of the hand device and to minimize the damage to the worker or the like when the worker or the like is in the vicinity of the hand device.

  As described above, since the drive device 1 according to the present embodiment uses the vibration-type actuator 2 having a high torque density, a large torque can be obtained without using a reduction gear having a large reduction ratio with a large size. As a result, it is possible to make the first power transmission system for performing an operation with priority given to the drive speed compact and the second power transmission system that outputs a large torque using a simple speed reduction system. Further, by using the non-energized holding force of the vibration-type actuator 2, it is not necessary to provide a brake or the like, thereby making it possible to reduce the size and weight.

  Furthermore, since the first power transmission system of the drive device 1 is directly connected from the motor shaft portion 3a to the output shaft portion 3b of the vibration type actuator 2, the operation of the members attached to the output shaft portion 3b is made with high accuracy Can be controlled. Therefore, in the hand device configured using the finger unit 20 using the drive device 1, the movements of the plurality of finger units 20 are controlled with high accuracy, and the gripping portion 24 is brought into contact with the gripping object substantially simultaneously and gripped It will be possible to As a result, it is possible to suppress the occurrence of a defect due to the timing at which the gripping unit 24 starts the contact with the gripping target being shifted. Further, by bringing the gripping portion 24 into contact with the object to be grasped through the first power transmission system, the gripping force error due to the inertia force generated at the start of gripping can be reduced, so that the first power transmission system to the second power transmission system The amplification of the torque error due to the reduction ratio can be minimized.

  Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various embodiments within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of the present invention, and it is also possible to combine each embodiment suitably. For example, another component having the same function can be used for each of the torque limiter 5, the one-way clutch 7 and the meshing clutch 6 that constitute the drive device 1. Also, although the finger unit 20 shown in FIG. 4 has a configuration in which two drive devices 1 are mounted, the finger unit is configured by mounting one or three or more drive devices 1. It is also possible. The driving device 1 is also suitably used to rotationally drive an arm in a joint or the like to which the arm is connected in an articulated robot.

Reference Signs List 1 drive device 2 vibration type actuator 3a motor shaft 3b output shaft 4a drive shaft 4b driven shaft 5 torque limiter 6 meshing clutch 7 one-way clutch 8 first gear 9 second gear 20 finger unit 22 finger 24 grip 27a finger drive 27b grip drive

Claims (8)

Vibration type actuator,
A motor shaft that rotates by driving the vibration-type actuator;
An output shaft unit for outputting the rotational driving force of the motor shaft unit to the outside;
A first power transmission system and a second power transmission system for transmitting the rotational drive force of the motor shaft to the output shaft;
The path through which the rotational drive force of the motor shaft is transmitted to the output shaft according to the rotational direction of the motor shaft and the torque generated by the vibration-type actuator is the first power transmission system and the second power transmission And a drive device characterized by switching between systems. The first power transmission system is a path for directly transmitting the rotation of the motor shaft to the output shaft,
2. The drive device according to claim 1, wherein the second power transmission system is a path for reducing the rotational speed of the motor shaft and increasing torque to transmit the torque to the output shaft. The first power transmission system is configured by connecting the motor shaft to the output shaft via a torque limiter,
The torque limiter directly transmits the rotation of the motor shaft to the output shaft regardless of the rotational direction of the motor shaft when the torque generated by the vibration-type actuator is small by a predetermined amount. And idle when the torque generated by the vibration-type actuator is equal to or greater than the predetermined magnitude,
The path according to claim 2, wherein a path through which the rotation of the motor shaft is transmitted to the output shaft is switched from the first power transmission system to the second power transmission system by causing the torque limiter to idle. Drive device.   The second power transmission system is characterized in that the motor shaft portion is connected to the output shaft portion via a first gear, a meshing clutch, a one-way clutch and a second gear. The drive device according to claim 3.   When the rotation of the motor shaft portion is directly transmitted to the output shaft portion via the torque limiter, the engagement of the meshing clutch is disengaged by disengagement of the meshing clutch, or the rotation of the second gear is caused. The drive unit according to claim 4, wherein the one-way clutch slips in accordance with. The first gear has a first small gear portion attached to the motor shaft portion, and a first large gear portion meshing with the first small gear portion and having a larger number of teeth than the first small gear portion. ,
The second gear has a second large gear portion attached to the output shaft portion, and a second small gear portion meshing with the second large gear portion and having a smaller number of teeth than the second large gear portion. ,
The drive device according to claim 4 or 5, wherein when the torque limiter is idled, the meshing clutch and the one-way clutch are in a connected state. The meshing clutch has a moving member and a fixed member, and switches between a connected state and a released state of the moving member and the fixed member according to the rotation direction of the first large gear portion.
The one-way clutch has an inner ring coaxially connected to the fixed member and an outer ring coaxially connected to the second small gear portion, and the angular velocity difference between the inner ring and the outer ring is determined depending on the magnitude and positive or negative The driving apparatus according to claim 6, wherein the connection state and the release state are switched. A robot comprising the drive device according to any one of claims 1 to 7.

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