JP6963310B2 - Actuator and actuator operation control method - Google Patents

Description

The present invention relates to an actuator and a method of controlling the operation of the actuator.

Conventionally, actuators for use in manipulators and robots have been developed.
Such actuators are required to have characteristics of high speed, high torque, small size, light weight, and high back drivability.
Here, an actuator using a speed reducer is known in order to realize small size, light weight, and high torque, but the use of the speed reducer significantly deteriorates the back drivability of the actuator.
Therefore, a series elastic actuator in which mechanical parts such as a spring, a damper, and a clutch are connected to an output shaft of a geared motor has been proposed (see, for example, Non-Patent Document 1).
This series elastic actuator aims to realize energy saving and high back drivability.
Further, an actuator in which a clutch is connected (see, for example, Non-Patent Document 2), an actuator using both a spring and a clutch (see, for example, Non-Patent Document 3), and the like have also been proposed.

G. Pratt and M. Williamson, "Series elastic actuators," in Proc. 1995 IEEE / RSJ Int. Conf. Intelligent Robots and Systems, vol. 1, August. 1995, pp. 399-406. N. Lauzier and C.I. Gosselin, “Series clutch actuators for safe physical human-robot intervention,” in Proc. 2011 IEEE Int. Conf. Robotics and Automation, May 20111, pp. 5401-5406. D. F. B. Haeufle, M. et al. D. Taylor, S.A. Schmitt, and H. Gayer, "A cluched parallel elastic actuator Concept: Towers energy effective power legs in prosthetics and robotics," in Proc. 4th IEEE RAS EMBS Int. Conf. Biomedical Robotics and Biomechatronics, 2012, Jun. 2012, pp. 1614-1619.

However, in the conventional techniques including the techniques described in Non-Patent Documents 1 to 3, springs and clutches are connected mainly for recovery of back drivability deteriorated by a speed reducer and energy saving. .. On the other hand, by providing the speed reducer, not only the back drivability is lowered, but also the maximum rotation speed of the actuator is lowered at the same time.
Therefore, it has been difficult to realize high-speed operation with a conventional actuator equipped with a speed reducer.

An object of the present invention is to realize a higher speed operation in an actuator including a speed reducer.

In order to solve the above problems, the actuator according to one aspect of the present invention is
A force / torque source that has a first deceleration mechanism and generates a driving force for an output unit that performs output operation.
A transmission control mechanism installed in a transmission path of the driving force generated by the force / torque source and controlling the transmission of the driving force to the output unit.
In the driving force transmission path, one end is connected to the position on the force / torque source side with respect to the point where the transmission control mechanism controls the transmission of the driving force to the output unit, and the position on the output unit side. With the first elastic member whose other end is connected to
It is characterized by having.

According to the present invention, it is possible to realize a higher speed operation in an actuator including a speed reducer.

It is a block diagram which shows the basic principle of this invention. It is a figure which shows the board diagram of the back drivability. It is a block diagram which shows the functional structure of the actuator of this invention. It is an external view which shows the apparatus configuration example of the actuator which concerns on 1st Embodiment. It is a figure which shows the result of having performed the evaluation experiment with the actuator of FIG. 4 and the geared motor alone about the movement of the output shaft of a clutch with respect to the input of an elastic force by an elastic member. It is a figure which shows the result of having performed the evaluation experiment with the actuator of FIG. 4 and the geared motor alone about the movement of the output shaft of a clutch with respect to the input of an elastic force by an elastic member. It is a figure which shows the result of having performed the evaluation experiment with the actuator of FIG. 4 and the geared motor alone about the movement of the output shaft of a clutch with respect to the input of an elastic force by an elastic member. It is an external view which shows the apparatus configuration example of the actuator which concerns on 2nd Embodiment. It is a block diagram which shows the structure which further includes a reduction gear on the output shaft of the actuator which has the structure of FIG. It is a block diagram which shows the structure which further includes the elastic member connected to the input shaft and output shaft of a clutch in the actuator which has the structure of FIG. It is a schematic diagram which shows the movement of the output shaft of a clutch when the engaging force of a clutch is changed when the actuator stops a normal operation (rotational drive of an output shaft by a geared motor). It is a schematic diagram which shows the movement of the output shaft of a clutch when the engaging force of a clutch is changed when the actuator stops a normal operation (rotational drive of an output shaft by a geared motor). It is a block diagram which shows the configuration example at the time of performing the linear motion operation as the output of an actuator. It is a schematic diagram which shows the configuration example in the case of constructing a parallel mechanism having a multi-degree of freedom by an actuator. It is a schematic diagram which shows the configuration example in the case of constructing a parallel mechanism having a multi-degree of freedom by an actuator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the basic principle applied to the actuator and the actuator motion control method according to the present invention will be described.

[Basic principle]
FIG. 1 is a block diagram showing the basic principle of the present invention.
As shown in FIG. 1, the actuator 1 according to the present invention includes a geared motor 10, a clutch 20, and an elastic member 30.

In the geared motor 10, the housing 10a is fixed to the support portion B, and a driving force for rotating the output shaft 10b is generated. Further, the geared motor 10 has a built-in speed reducer that changes the rotation speed and the rotation torque, and the output of the geared motor 10 is transmitted to the output shaft 10b via the speed reducer.

The clutch 20 uses the output shaft 10b of the geared motor 10 as the input shaft 20a, and changes the engagement state between the input shaft 20a and the output shaft 20b. Specifically, the clutch 20 is composed of a power transmission device such as an electromagnetic clutch, a powder clutch, a functional fluid clutch, and a piezo clutch, and controls the fastening force between the input shaft 20a and the output shaft 20b. In the following description, it is assumed that the clutch 20 is composed of an electromagnetic clutch.

The elastic member 30 is composed of a member that generates an elastic force such as a coil spring (tension spring), a torque spring, a compression spring, and a constant load spring, and one end of the elastic member 30 is connected to the housing 10a side of the geared motor 10. The other end is connected to the output shaft 20b side of the clutch 20. Here, the housing 10a side of the geared motor 10 is a portion integrally fixed with the housing 10a including the support portion B and the like. Further, the output shaft 20b side of the clutch 20 is a portion that is on the terminal side of the fastening force control point of the clutch 20 and rotates together with the output shaft 20b in the transmission path of the driving force generated by the geared motor 10. .. In the following description, it is assumed that the elastic member 30 is composed of a coil spring.

With such a configuration, the actuator 1 according to the present invention operates as follows.
That is, when the geared motor 10 rotates the output shaft 10b while the clutch 20 connects (fixes) the input shaft 20a and the output shaft 20b, the output shaft 10b (input shaft 20a) and the output shaft 20b become one. Rotate.
At this time, since the geared motor 10 is provided with a speed reducer, it can be driven with high torque.

Further, since one end of the elastic member 30 is connected to the housing 10a side of the geared motor 10 and the other end is connected to the output shaft 20b side of the clutch 20, as the geared motor 10 rotates, the output shaft 10b is rotated. The elastic member 30 generates an elastic force in a direction that hinders its rotation, and accumulates elastic energy corresponding to the rotational torque of the geared motor 10.
Then, when the engaging force of the clutch 20 is set to zero and the connection between the input shaft 20a and the output shaft 20b is released according to the preset control conditions, the clutch 20 is accumulated in the elastic member 30 on the output shaft 20b. The elastic energy gives a force to rotate in the direction opposite to the rotation direction of the geared motor 10.

Therefore, when the clutch 20 is released, the output shaft 20b can be rotated at high speed in the direction opposite to the rotation direction by the geared motor 10.
Further, in the actuator 1, when the output shaft 20b of the clutch 20 is rotated by the geared motor 10 and an external force is applied due to contact with an object or the like, the clutch 20 is released and the driving force to the output shaft 20b is released. The transmission can be released, and the elastic member 30 can apply an auxiliary force for rotating the output shaft 20b of the clutch 20 in the direction in which an external force is applied.
Therefore, when the clutch 20 is released, the output shaft 20b can be rotated at high speed in a direction corresponding to an external force, and the back drivability of the actuator 1 can be improved.
As described above, according to the present invention, it is possible to realize a higher speed operation in the actuator provided with the speed reducer.

[Analysis of physical characteristics]
Next, the physical characteristics required for the actuator 1 will be described.
By providing a deceleration mechanism, a compact and high-output actuation mechanism is realized. At this time, if the geared motor 10 is regarded as one inertial system and the efficiency in the gear is 1, the equation of motion is expressed by the equation (1).

^{_{J g · d 2 θ g =}} G r · K t · I m + τ ext -D g · dθ g -τ g fric (1)
However, d is a differential operator and
J _g = _Gr ² · J _m (2)
D _g = _Gr ² · D _m (3)
^{_{τ g fric = G r · τ}} m fric (4)
θ _g = 1 / _Gr · θ _m (5)
Is.

_{Here, J, θ, G r,} K t, I, τ, D, g, m, ext, fric is served represents inertia, angles, gear ratio, torque constant, current, torque, viscosity constant, the geared motor It represents a character, a subscript representing a single motor, a subscript representing an external force, and a subscript representing friction. Further, the maximum rotation speed ω ^max and the maximum acceleration α ^{max of the} motor are expressed as equations (6) and (7), respectively.

ω _g ^max = 1 / _Gr · ω _m ^max (6)
^{_{α g max = 1 / G r}} · α m max = (G r · K t · I m max + τ ext -τ g fric) / J g (7)

Further, the transfer function G ^back from the external force τ ^ext to the displacement θ _g indicates the back drivability of the system and is expressed by Eq. (8).
G _g ^back = θ _g / τ ^ext = 1 / (J _g · s ² + D _g · s) (8)
The higher the gain of the transfer function representing back drivability, the higher the back drivability. Actually, ^{considering the influence of the static friction τfric} , the equivalent back drivability gain is smaller than that in the equation (8).

From the above, the larger the gear ratio, the lower the back drivability, the maximum acceleration and the maximum rotation speed.
The actuator 1 according to the present invention has a configuration in which the clutch 20 and the elastic member 30 are connected as shown in FIG. 1 in order to recover the back drivability, the maximum acceleration, and the maximum rotation speed lowered by the speed reducer.
That is, the clutch 20 is connected to the output shaft 10b of the geared motor 10, the connection between the input shaft 20a and the output shaft 20b of the clutch 20 is controlled, the equivalent inertia and the amount of friction are reduced, and then the elasticity is as described above. By converting the elastic energy stored in the member 30 into kinetic energy, the actuator 1 according to the present invention realizes high-speed motion.

The actuator 1 according to the present invention has two operation modes depending on whether the clutch 20 is engaged or disconnected.
(1) Connected state In the connected state, the actuator 1 is a system in which the inertia of the geared motor 10 and the inertia of the clutch 20 operate integrally, and is a system that receives an elastic force from the elastic member 30 as a resistance. The equations of motion in the actuator 1 in the mode corresponding to the connected state are expressed as equations (9) and (10).
^{_{(J g + J c) d}} 2 θ c = G r · K t · I m + τ ext -D g · dθ c -K · θ c -τ g fric (9)
d ² θ _g = d ² θ _c (10)
However, K is the spring constant of the elastic member 30, and the subscript c is a subscript representing the clutch 20.

(2) Unconnected state In the unconnected state, the output of the geared motor 10 is cut off, so that the system operates only by an external force and torque by the elastic member 30. The equations of motion in the actuator 1 in the mode corresponding to the unconnected state are expressed by equations (11) and (12).
J _c · d ² θ _c = τ ^ext −K · θ _c (11)
^{_{J g · d 2 θ g =}} G r · K t · I m + τ ext -D g · dθ g -τ g fric (12)
However, here, the friction of the clutch 20 is regarded as zero.

_{Here, the back drivability G on} ^back and G _off ^back in the connected state and the unconnected state are represented by the equations (13) and (14) from the equations (9) and (11), respectively.
G _on ^back = 1 / ((J _g + J _c ) · s ² + D _g · s + K) (13)
G _off ^back = 1 / (J _c · s ² + K) (14)
Note that s is a Laplace operator.
Generally, the inertia _Jc of the clutch 20 and the friction torque of the clutch 20 are _{sufficiently small as compared with the equivalent inertia J g} and the friction torque of the geared motor 10 having a high gear ratio.

FIG. 2 is a diagram showing a Bode diagram of back drivability.
In FIG. 2, the back drivability of the geared motor 10 alone (dashed line), the back drivability of the actuator 1 to which the present invention is applied (broken line), and the unconnected state of the actuator 1 to which the present invention is applied. The back drivability (solid line) is shown respectively.
As shown in FIG. 2, when the back drivability of the actuator 1 to which the present invention is applied in the connected state and the back drivability of the geared motor 10 alone are compared, they show almost the same performance in the high frequency region.

On the other hand, it can be seen that the back drivability of the actuator 1 to which the present invention is applied in the unconnected state is higher than the back drivability of the geared motor 10 alone in the high frequency region.
This is because the influence of inertia and the influence of friction torque are small in the system of the clutch 20 alone (unconnected state).
As described above, the actuator 1 to which the present invention is applied can switch between a compact, lightweight, high torque system having the characteristics of the geared motor 10 and a system having high back drivability by switching the operation mode.

[Specification of operating conditions]
When the actuator 1 having the above-mentioned physical characteristics operates at the maximum acceleration or the maximum rotation speed of the geared motor 10, the output torque from the geared motor 10 is accumulated in the elastic member 30, and the operation modes are connected. To switch to the unconnected state (that is, release the clutch 20). As a result, high-speed operation is realized by converting the elastic energy of the elastic member 30 into kinetic energy.
At this time, the operation mode is coupled state, when the torque applied to the elastic member 30 and tau _on, the elastic energy E _k to be stored in the elastic member 30, represented by the formula (15).
E _k = (1/2) ・ K ・ (τ _on / K) ² = (1/2) ・ τ _on ² / K (15)

Since this elastic energy is converted into kinetic energy, the equation (16) holds for _{the maximum speed ω c} ^{max when the clutch 20 is released from the energy conservation law.}
E _k = (1/2) ・ J _c・ ω _c ^max2 (16)
Therefore, the maximum speed ω _c ^max when the clutch 20 is released is expressed by the equation (17).
ω _c ^max = τ _on / (J _c · K) ^1/2 (17)
_{Therefore, by selecting the elastic member 30 so that ω c} ^max > ω _g ^max with respect to the maximum speed ω _g ^max of the geared motor 10 and determining the torque input from the geared motor 10, the geared motor 10 alone It is possible to realize faster movement than that.
That is, by properly using the unconnected state and the connected state in the actuator 1 to which the present invention is applied, higher back drivability and higher speed motion can be realized.

[Functional configuration]
When the actuator is configured by the above-mentioned basic principle, it can be realized as various types of devices having the following functional configurations.
FIG. 3 is a block diagram showing a functional configuration of the actuator 1 of the present invention.
As shown in FIG. 3, the actuator 1 includes a support portion 110, a force / torque source 120, a transmission mechanism 130, a connection / non-connection mechanism 140 (transmission control mechanism), an output shaft 150, and an elastic mechanism 160. , A drive circuit 170, a computer 180, and a power source 190.

Of these, the support portion 110 corresponds to the support portion B in FIG. 1, the force / torque source 120 corresponds to the motor portion of the geared motor 10 in FIG. 1, and the transmission mechanism 130 corresponds to the speed reducer of the geared motor 10 in FIG. It corresponds to. Further, the connecting / non-connecting mechanism 140 corresponds to the clutch 20 in FIG. 1, and the elastic mechanism 160 corresponds to the elastic member 30 in FIG.

The support portion 110 supports the main body of the force / torque source 120, and is composed of, for example, a fixed base or a pedestal on which the actuator 1 is installed. The support portion 110 does not necessarily have to be fixed to the ground, and when the actuator 1 is configured as a movable device, the main body of the actuator 1 can be the support portion 110 or the like.

The force / torque source 120 has a main body fixed to the support portion 110, and generates a driving force for rotating the output shaft 150 under the control of the driving circuit 170.
The transmission mechanism 130 includes a gear mechanism and outputs the rotation output by the force / torque source 120 at different speeds.

The connection / non-connection mechanism 140 transmits the rotation input from the transmission mechanism 130 to the output side by changing the state in which the input side and the output side are connected or not connected according to the control of the drive circuit 170. Switch whether to do or not.
The output shaft 150 is a member that outputs the rotation input from the connecting / disconnecting mechanism 140. One end of the elastic mechanism 160 is connected to the output shaft 150. Further, the specific form of the output shaft 150 can be variously configured according to the mounting purpose of the actuator 1, and can be configured to include, for example, a disk-shaped member, an arm-shaped member, a drill-shaped member, or the like. ..

The elastic mechanism 160 includes an elastic member having one end connected to the output shaft 150 and the other end connected to the support portion 110, and the elastic energy is generated by a relative position change when the output shaft 150 is rotationally driven with respect to the support portion 110. When the output shaft 150 is released from being fixed to the support portion 110, the stored elastic energy causes the output shaft 150 to rotate in the direction opposite to the direction in which the output shaft 150 is rotationally driven.

The drive circuit 170 controls the force / torque source 120 and the coupling / disconnection mechanism 140 according to the control rules in the computer 180. That is, the drive circuit 170 outputs the electric power supplied from the power source 190 to the force / torque source 120, and also outputs a drive signal for controlling the rotation speed and torque of the force / torque source 120. Further, the drive circuit 170 outputs the electric power supplied from the power source 190 to the connected / unconnected mechanism 140, and in the connected / unconnected mechanism 140, the input side and the output side are connected or connected. Outputs a drive signal to change the state in which it is not.

The computer 180 controls the entire actuator 1 according to a predetermined control rule by executing a control program or the like according to the mounting purpose of the actuator 1.
The power source 190 is composed of a battery, a commercial power source, or the like, and supplies electric power for the actuator 1 to operate.
In addition to such a functional configuration, the actuator 1 can be provided with various additional functions.
For example, the rotating shaft (output shaft) of the force / torque source 120, the input shaft and output shaft of the connecting / non-connecting mechanism 140, the output shaft 150, and the like may be appropriately provided with sensors for detecting these rotation angles and torques. It is possible.
Hereinafter, a specific embodiment of the actuator 1 having the above-mentioned functional configuration will be described.

[First Embodiment]
[composition]
FIG. 4 is an external view showing an example of a device configuration of the actuator 1.
As shown in FIG. 4, the actuator 1 includes a geared motor 10, a clutch 20, and a plurality of elastic members 30.

In FIG. 4, the configurations of the geared motor 10, the clutch 20, and each elastic member 30 are the same as those described in FIG.
Further, in the present embodiment, the housing 10a of the geared motor 10 is fixed to the plate-shaped first support portion B1, and the output shaft 10b of the geared motor 10 is connected to the clutch 20.

The clutch 20 is installed on the plate-shaped second support portion B2, and the output shaft 10b and the input shaft 20a connected from the geared motor 10 are configured as an integral member. The first support portion B1 and the second support portion B2 are configured as an integral member.
Further, the output shaft 20b of the clutch 20 can be switched between a connected state and a non-connected state with the input shaft 20a, and the tip thereof is formed in a disk shape. One end of each of the plurality of elastic members 30 is connected to the disk-shaped portion forming the tip of the output shaft 20b.
In the present embodiment, the elastic member 30 is composed of two coil springs 31 and 32, and one end of each of the two coil springs 31 and 32 sandwiches the center in a disk-shaped portion forming the tip of the output shaft 20b. It is connected to the symmetrical positions x1 and x2.

Further, the other ends of the two coil springs 31 and 32 constituting the elastic member 30 are connected to the plate-shaped third support portion B3. The third support portion B3 is configured as a member integrated with the first support portion B1 and the second support portion B2. Further, the third support portion B3 is installed so that the disk surface of the disk-shaped portion constituting the tip of the output shaft 20b is parallel to the disk surface. In the present embodiment, the distance between the third support portion B3 and the disk-shaped portion constituting the tip of the output shaft 20b is about the same as the natural length of the coil springs 31 and 32 constituting the elastic member 30. There is. Further, when the rotation position of the output shaft 20b is the reference position (rotation angle 0 degree), the positions x1 and x2 of the disk surface to which one ends of the coil springs 31 and 32 are connected and the other ends are connected. The positions y1 and y2 of the plate surface of the third support portion B3 are set to face each other. Therefore, when the output shaft 20b of the clutch 20 is rotationally driven, the coil springs 31 and 32 constituting the elastic member 30 are respectively extended from their natural lengths, and elastic energy is accumulated according to the degree of extension. ..

[motion]
Next, the operation will be described.
When the actuator 1 of the device configuration example shown in FIG. 4 operates, the rotation position of the output shaft 20b of the clutch 20 is adjusted to the reference position (rotation angle 0 degrees) in the initial state.
Then, when the actuator 1 performs a normal operation (rotational drive of the output shaft 20b by the geared motor 10), the clutch 20 is brought into the engaged state.
When the geared motor 10 rotates the output shaft 20b of the clutch 20 from the initial state, the coil springs 31 and 32 constituting the elastic member 30 are respectively extended from their natural lengths. At this time, the length at which the coil springs 31 and 32 extend is determined according to the rotational torque output by the geared motor 10.

Here, it is assumed that the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor) in response to an external force being applied to the clutch 20 in a direction opposite to the rotation direction of the geared motor 10. .. The application of an external force can be detected, for example, as an input of disturbance, and can be determined from the relationship between the drive current of the geared motor 10 and the rotation angle of the output shaft 10b, or a rotary encoder on the output shaft 20b of the clutch 20. It can be detected by providing a position sensor, a torque sensor, or the like.
Then, the clutch 20 is switched to the unconnected state, and the transmission of the driving force from the geared motor 10 to the output shaft 20b is released. As a result, the output shaft 20b of the clutch 20 is in a state in which the elastic force (restoring force to the natural length) from the coil springs 31 and 32 constituting the elastic member 30 acts.

That is, an auxiliary force for rotating the output shaft 20b of the clutch 20 in the direction opposite to the rotation direction of the geared motor 10 is applied.
As a result, when the clutch 20 is released, the output shaft 20b can be rotated at high speed in the direction opposite to the rotation direction of the geared motor 10, and the back drivability of the actuator 1 can be improved.
That is, it is possible to realize a higher speed operation in the actuator 1 provided with the speed reducer.

[effect]
5A to 5C are diagrams showing the results of an evaluation experiment on the movement of the output shaft 20b of the clutch 20 with respect to the input of the elastic force by the elastic member with the actuator 1 of FIG. 4 and the geared motor 10 alone.
Note that FIG. 5 (A) is a diagram showing an angular response value, FIG. 5 (B) is a diagram showing an angular velocity response value, and FIG. 5 (C) is an output as a moving distance (rotation angle of the output shaft 20b of the clutch 20). It is a figure which shows the relationship with the maximum rotation speed.
In FIGS. 5A to 5C, the actuator 1 performs a normal operation (rotational drive of the output shaft 20b by the geared motor 10) before 0 [s], and in 0 [s] to about 0.4 [s]. The rotational drive is stopped, and the elastic member 30 holds the energy stored in the elastic member 30. After that, the clutch 20 is released at about 0.4 [s].

As shown in FIGS. 5A and 5B, when the output shaft 20b is rotationally driven (held at a predetermined angle) within the maximum operating range of the geared motor 10, the input of the driving force to the output shaft 20b is stopped. Then, in the case of the geared motor 10 alone, it is affected by the decrease in the rotational speed due to the speed reducer. Therefore, within the range of the maximum rotation speed (positive direction and negative direction) of the geared motor 10, the output shaft 20b is rotated in the direction opposite to the rotation direction of the geared motor 10. Therefore, it takes about 0.4 [s] for the output shaft 20b to return to the reference position (rotation angle 0 degrees), and the speed at which the output shaft 20b rotates in the direction opposite to the rotation direction by the geared motor 10 is low. It has become.

On the other hand, in the actuator 1 of the present invention, the clutch 20 is switched to the unconnected state, and the elastic energy stored in the elastic member 30 causes the output shaft 20b to rotate in the direction opposite to the rotation direction of the geared motor 10. Assist in that. Therefore, the output shaft 20b is rotated in the direction opposite to the rotation direction of the geared motor 10 beyond the maximum rotational speed of the geared motor 10. Therefore, the output shaft 20b immediately returns to the reference position (rotation angle 0 degrees), and the speed at which the output shaft 20b rotates in the direction opposite to the rotation direction by the geared motor 10 is higher.

As shown in FIG. 5C, in the actuator 1 of the present invention, the greater the angle at which the geared motor 10 rotationally drives the output shaft 20b, the greater the elastic energy stored in the elastic member 30, so that the clutch 20 is engaged. When opened, the speed at which the output shaft 20b rotates (maximum rotation speed) becomes higher.
On the other hand, in the geared motor 10 alone, the rotation speed of the output shaft 20b is limited to the range of the maximum rotation speed of the geared motor 10.
That is, the larger the angle at which the geared motor 10 rotationally drives the output shaft 20b, the more remarkable the effect of the actuator 1 in the present invention will be.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
[composition]
FIG. 6 is an external view showing an example of device configuration of the actuator 1 according to the second embodiment.
In the device configuration example shown in FIG. 6, flange portions having substantially the same diameter are formed in a part of the housing 10a of the geared motor 10 and the output shaft 20b of the clutch 20, and an elastic member 30 is formed between these flange portions. A plurality of coil springs are connected.
Hereinafter, a specific description will be given.

The housing 10a of the geared motor 10 is fixed to a support portion B (not shown), and the output shaft 10b of the geared motor 10 is connected to the clutch 20. Further, the housing 10a of the geared motor 10 includes a flange portion 11a having a circular outer edge having a radius larger than that of the other portion in a part in the axial direction. The diameter of the flange portion 11a is larger than the diameter of the housing of the clutch 20, and the flange surface of the flange portion 11a faces the flange portion 21b of the output shaft 20b of the clutch 20, which will be described later.

The clutch 20 is fixed to the housing 10a of the geared motor 10, and the output shaft 10b and the input shaft 20a connected from the geared motor 10 are configured as an integral member.
Further, the output shaft 20b of the clutch 20 can be switched between a connected state and a non-connected state with the input shaft 20a, and a flange portion 21b having a circular outer edge having a radius expanded in a part in the axial direction as compared with the other part. It has. The flange surface of the flange portion 21b faces the flange surface of the flange portion 11a provided in the housing 10a of the geared motor 10.

The elastic member 30 is composed of a plurality of coil springs 30-1 to 30-n (n is an integer of 2 or more). One end of each of the coil springs 30-1 to 30-n is connected to the flange surface of the flange portion 11a, and the other end of each of the coil springs 30-1 to 30-n is connected to the flange surface of the flange portion 21b. Has been done. Here, the opposing flange surfaces of the flange portions 11a and 21b are installed so as to be parallel to each other. In the present embodiment, the distance between the flange surfaces of the flange portions 11a and 21b facing each other is about the same as the natural length of the coil springs 30-1 to 30-n constituting the elastic member 30. Further, when the rotation position of the output shaft 20b is the reference position (rotation angle 0 degree), the positions X1 to the flange surface of the flange portion 11a to which one end of the coil springs 30-1 to 30-n is connected. Xn and the positions Y1 to Yn of the flange surface of the flange portion 21b to which the other end is connected are set to face each other. Therefore, when the output shaft 20b of the clutch 20 is rotationally driven, the coil springs 30-1 to 30-n constituting the elastic member 30 are each extended from their natural lengths, and elastic energy corresponding to the degree of extension is accumulated. The Rukoto.

[motion]
Next, the operation will be described.
When the actuator 1 of the device configuration example shown in FIG. 6 operates, the rotation position of the output shaft 20b of the clutch 20 is set as the reference position in the initial state.
Then, when the actuator 1 performs a normal operation (rotational drive of the output shaft 20b by the geared motor 10), the clutch 20 is brought into the engaged state.
When the geared motor 10 rotates the output shaft 20b of the clutch 20 from the initial state, the coil springs 30-1 to 30-n constituting the elastic member 30 are respectively extended from their natural lengths. At this time, the length at which the coil springs 30-1 to 30-n extend is determined according to the rotational torque output by the geared motor 10.

Here, it is assumed that the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor) in response to an external force being applied to the clutch 20 in a direction opposite to the rotation direction of the geared motor 10. .. As described above, the application of an external force can be determined from the relationship between the drive current of the geared motor 10 and the rotation angle of the output shaft 10b, or the output shaft 20b of the clutch 20 is provided with a position sensor such as a rotary encoder or a torque sensor. It can be detected by such things.
Then, the clutch 20 is switched to the unconnected state, and the transmission of the driving force from the geared motor 10 to the output shaft 20b is released. As a result, the output shaft 20b of the clutch 20 is in a state in which the elastic force (restoring force to the natural length) from the coil springs 30-1 to 30-n constituting the elastic member 30 acts.

That is, an auxiliary force for rotating the output shaft 20b of the clutch 20 in the direction opposite to the rotation direction of the geared motor 10 is applied.
As a result, when the clutch 20 is released, the output shaft 20b can be rotated at high speed in the direction opposite to the rotation direction of the geared motor 10, and the back drivability of the actuator 1 can be improved.

That is, it is possible to realize a higher speed operation in the actuator 1 provided with the speed reducer.
Further, since the actuator 1 in the present embodiment has a configuration in which the coil springs 30-1 to 30-n constituting the elastic member 30 are arranged around the clutch 20, the entire actuator 1 can be miniaturized.

[Modification 1]
In the above-described embodiment, the output shaft 20b of the actuator 1 is provided with a speed reducer, so that the torque can be further increased.
FIG. 7 is a block diagram showing a configuration in which a speed reducer 40 is further provided on the output shaft 20b of the actuator 1 having the configuration of FIG.
As shown in FIG. 7, the output shaft 20b is provided with the speed reducer 40, and the other end of the elastic member 30 can be connected to the output shaft of the speed reducer 40.
In this case, if the gear ratio of the reduction gear 40 is large, the back drivability is lowered when an external force is input. Therefore, the gear ratio of the reduction gear 40 is smaller, and the gear ratio of the reduction gear of the geared motor 10 is high. It is desirable to make it larger.
With such a configuration, the output torque of the actuator 1 can be further increased. Further, with such a configuration, it is possible to further adjust the rotation speed output by the geared motor 10.

[Modification 2]
In the above-described embodiment, an elastic member 30A having one end connected to the input shaft 20a of the clutch 20 and the other end connected to the output shaft 20b of the clutch 20 can be provided.
FIG. 8 is a block diagram showing a configuration in which the actuator 1 having the configuration of FIG. 1 further includes an elastic member 30A connected to the input shaft 20a and the output shaft 20b of the clutch 20.
As shown in FIG. 8, since the elastic member 30A is connected to the input shaft 20a and the output shaft 20b of the clutch 20, when the clutch 20 is in the connected state, the input of the clutch 20 is not expanded or compressed. It rotates together with the shaft 20a and the output shaft 20b.
When the clutch 20 is disconnected, the elastic energy stored in the elastic member 30 causes the output shaft 20b to rotate with respect to the input shaft 20a of the clutch 20. At this time, the elastic member 30A generates an elastic force in a direction that prevents the elastic member 30 from rotating the output shaft 20b.
With such a configuration, the equilibrium point of the output shaft 20b when the clutch 20 is in the unconnected state can be changed.

[Modification 3]
In the above-described embodiment, the clutch 20 switches the input shaft 20a and the output shaft 20b between the connected state and the unconnected state, but the engaging force of the clutch 20 can be adjusted.
For example, in the case of an electromagnetic clutch, the fastening force can be adjusted to a continuous value from the open state to the fixed state by adjusting the drive current amount.
By adjusting the engaging force of the clutch 20 in this way, when the actuator 1 stops the normal operation (rotational drive of the output shaft 20b by the geared motor 10), the direction is opposite to the rotational direction by the geared motor 10. The speed at which the output shaft 20b rotates can be adjusted.
9A and 9B are schematics showing the movement of the output shaft 20b of the clutch 20 when the fastening force of the clutch 20 is changed when the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor). It is a figure.
9A is a diagram showing an angular response value, and FIG. 9B is a diagram showing an angular velocity response value.
As shown in FIGS. 9A and 9B, when the engaging force of the clutch 20 is changed, the movement of the output shaft 20b when the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor) is small. It is possible to adjust to various angular velocities, from a characteristic that responds at an angular velocity (characteristic Q1 in FIG. 9B) to a characteristic that responds at a large angular velocity (characteristic Q5 in FIG. 9B). As a result, the response value of the speed is adjusted to various speeds from the characteristic that the output shaft 20b rotates at the lowest speed (characteristic P1 in FIG. 9A) to the characteristic that the output shaft 20b rotates at a high speed (characteristic P5 in FIG. 9A). It becomes possible.

[Modification example 4]
In the above-described embodiment, the case where the rotation operation is performed as the output of the actuator 1 has been described as an example, but the present invention is not limited to this. For example, the present invention can be applied even when a linear motion operation is performed as an output of the actuator 1.
FIG. 10 is a block diagram showing a configuration example in which a linear motion operation is performed as an output of the actuator 1.
As shown in FIG. 10, the actuator 1 includes a geared motor 10, an elastic member 30, a ball screw 50, a bearing 60, a ball nut 70, a connecting / disconnecting mechanism 80, and an output unit 90. There is.
The actuator 1 shown in FIG. 10 constitutes a linear motion mechanism using a ball screw 50.
That is, in the geared motor 10, the housing 10a is fixed to the support portion B, and the output shaft 10b is a ball screw 50.
The ball screw 50 is rotatably supported by a bearing 60, and a thread groove is formed on the surface of the ball screw 50.
Further, a ball nut 70 having a thread groove corresponding to the thread groove of the ball screw 50 is inserted into the ball screw 50, and between the thread groove of the ball screw 50 and the thread groove of the ball nut 70. A ball bearing is installed. The movement of the ball nut 70 in the rotation direction is restricted so that the ball nut 70 does not rotate integrally with the rotation of the ball screw 50.
Therefore, when the ball screw 50, which is the output shaft 10b of the geared motor 10, rotates, the ball nut 70 moves linearly in the axial direction of the ball screw 50.

An output unit 90 is installed on the ball nut 70 via a connecting / non-connecting mechanism 80, and the other end of the elastic member 30 is connected to the output unit 90. One end of the elastic member 30 is connected to the support portion B.
That is, when the ball nut 70 linearly moves in the axial direction of the ball screw 50 in the direction away from the geared motor 10, the elastic member 30 extends and elastic energy is accumulated according to the moving distance.
The connecting / non-connecting mechanism 80 locks the ball nut 70 and the output unit 90, and the ball nut 70 and the output unit 90 move in a linear motion (connected state), and the ball nut 70 and the output unit 90. The lock with the ball nut 70 is released, and the output unit 90 switches to a state (disconnected state) in which the output unit 90 moves (slides or the like) in the direction of linear motion with respect to the ball nut 70.
In such a configuration, when the output unit 90 locked to the ball nut 70 linearly moves in the axial direction of the ball screw 50 in the direction away from the geared motor 10, the elastic member 30 extends according to the moving distance. And elastic energy is accumulated.
Then, when the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor) in response to an external force being applied to the output unit 90 due to contact with an object or the like, the coupling / non-connection mechanism 80 is used. The lock of the output unit 90 to the ball nut 70 can be released so that the output unit 90 can move in the direction of linear motion with respect to the ball nut 70. At this time, the elastic energy stored in the elastic member 30 can be used to apply an auxiliary force for moving in the direction approaching the geared motor 10.
Therefore, when the lock on the ball nut 70 is released by the connecting / disconnecting mechanism 80, the output unit 90 can be moved at high speed in the direction approaching the geared motor 10, and the back drivability of the actuator 1 is improved. Can be done.
That is, according to this modification, it is possible to realize a higher speed operation in the actuator provided with the speed reducer.

[Modification 5]
In the above-described embodiment, the actuator 1 can realize a system having a large number of degrees of freedom.
At this time, it is advantageous to use a parallel mechanism in order to prevent the mass from concentrating on the tip portion of the output.
11A and 11B are schematic views showing a configuration example when a parallel mechanism having multiple degrees of freedom is configured by the actuator 1.
FIG. 11A is a diagram showing a configuration example of a system (3 motors / 3 arm system) including three arms operated by one actuator 1.
In the case of the configuration example shown in FIG. 11A, a system with three degrees of freedom that can move in the directions of three axes orthogonal to each other is realized.
FIG. 11B is a diagram showing a configuration example of a system (6 motors / 6 arm system) including 6 arms operated by one actuator 1.
In the case of the configuration example shown in FIG. 11B, a system with 6 degrees of freedom that can move in the directions of three axes orthogonal to each other and can rotate around each axis is realized.
In addition to the configurations shown in FIGS. 11A and 11B, the present invention based on the above principle can be applied to a mechanism in which various gears and various motors are combined.
With these configurations, it is possible to realize a system with multiple degrees of freedom while avoiding the concentration of mass on the tip of the output. Further, also in these systems, it is possible to store elastic energy in the elastic member as the motor is driven, and to cancel the transmission of the output of the motor in response to an external force or the like.
As a result, when the actuator 1 stops the normal operation (rotational drive of the output shaft by the geared motor), the elastic energy can apply a force to operate the actuator 1 in the direction opposite to the operation by the motor. Back drivability can be improved.
That is, according to this modification, it is possible to realize a higher speed operation in the actuator provided with the speed reducer.

In the above-described embodiment, the position where both ends of the elastic member 30 are connected can be variously changed according to the specific form of the actuator 1.
For example, in the configuration of the first embodiment shown in FIG. 4, one ends of the two coil springs 31 and 32 are symmetrical positions x1 and x2 with the center in the disk-shaped portion forming the tip of the output shaft 20b. It is assumed that it is connected to, but it is not limited to this. That is, the coil springs 31 and 32 can be connected to positions different from the center in the disk-shaped portion constituting the tip of the output shaft 20b, or can be connected to positions other than symmetrical positions with the center in between. Is. Further, in this case, the length and elastic modulus of the coil springs 31 and 32 can also be selected according to the connection position.

Further, the actuator 1 according to the present invention can be applied to a system that performs an operation by a driving force and an operation by an external force in a direction opposite to the operation.
For example, the actuator 1 according to the present invention can be installed as a device that generates a driving force for a leg in a humanoid robot. In this case, the actuator 1 drives a shaft that swings the leg back and forth with respect to the hip joint. When the leg swings at high speed (running, jumping, etc.), the leg moves forward from the reference position and moves backward from the reference position, with the vertical lower part of the hip joint as the reference position for the rotation position. The operation of the legs is performed by the geared motor 10. On the other hand, when the leg swinging forward or backward is pulled back to the reference position, the clutch 20 is disengaged, and the elastic energy of the elastic member 30 is used to realize a high-speed movement.
This makes it possible to swing the legs at a rotation speed that exceeds the maximum rotation speed of the geared motor 10.
With such a configuration, the elastic energy can be accumulated in the elastic member 30 by the operation of absorbing the impact from the ground at the moment when the leg touches the ground.

Further, the actuator 1 according to the present invention can be installed as a device that generates a tightening force of a clamp holder of a machine tool. For example, in a decoding machine that performs lathe processing and milling processing, such a clamp holder is installed so that the tools can be automatically replaced.
Specifically, when the tool is held by the clamp holder, the clamp holder is driven by the geared motor 10. When the tool is replaced in the clamp holder, the clutch 20 is disengaged to assist the operation of releasing the holding of the tool by the clamp holder by the elastic energy stored in the elastic member 30.
As a result, the clamp holder can be miniaturized and the operation of the clamp holder can be speeded up.

In addition, the actuator 1 according to the present invention can be applied to an industrial manipulator or a mobile manipulator. By downsizing these manipulators, it is possible to reduce the output of the motor, so that energy saving and space saving of the device can be realized.
Further, the actuator 1 according to the present invention includes a rehabilitation robot (a robot that assists the rehabilitation of a patient), a wearable robot (a robot that assists the movement of a wearing human), and a prosthetic hand / leg robot (a part of a lost body). It can be applied to alternative robots) and the like. Since these robots require a contact operation with a human, high safety is desired, that is, high back drivability is required. On the other hand, by using the actuator 1 according to the present invention, it is possible to realize high back drivability while achieving miniaturization (wearable).

The above embodiment shows an example to which the present invention is applied, and does not limit the technical scope of the present invention. That is, the present invention can be modified in various ways such as omission and substitution without departing from the gist of the present invention, and various embodiments other than the above-described embodiment can be taken. Various embodiments and modifications thereof that can be taken by the present invention are included in the scope of the invention described in the claims and the equivalent range thereof.

1 actuator, 10 geared motor, 10a housing, 10b, 20b, 150 output shaft, 11a, 21b flange, 20 clutch, 20a input shaft, 30,30A elastic member, 31,32,30-1 to 30-n coil Spring, 40 speed reducer, 50 ball screw, 60 bearing, 70 ball nut, 90 output part, B, 110 support part, 120 force / torque source, 130 transmission mechanism, 80, 140 connected / unconnected mechanism, 160 elastic mechanism, 170 drive circuit, 180 computer, 190 power source

Claims (8)

A force / torque source that has a first deceleration mechanism and generates a driving force for an output unit that performs output operation.
A transmission control mechanism installed in the transmission path of the driving force generated by the force / torque source and controlling the transmission of the driving force to the output unit via a gear.
In the driving force transmission path, one end is connected to the position on the force / torque source side with respect to the point where the transmission control mechanism controls the transmission of the driving force to the output unit, and the position on the output unit side. A first elastic member whose other end is connected to and stores elastic energy by the output of the force / torque source.
With
The transmission control mechanism transmits the driving force of the force / torque source through the gear in the operation in one direction and the reverse direction of the output unit, and inputs the external force in the opposite direction to the output unit. If it is, to suppress the transmission of the driving force through said gear to said output section,
The output unit, when the transmission of the driving force through said gear to said output portion is suppressed by the transmission control mechanism, by the elastic energy stored in the first elastic member to the opposite direction An actuator characterized by having back drivability to operate. The actuator according to claim 1, wherein the output unit operates with back drivability equal to or higher than the maximum operating speed of the force / torque source by the elastic energy stored in the first elastic member. One end of the first elastic member is connected to a housing of the force / torque source or a portion to which the housing is fixed, and the other end is connected to a portion that performs an output operation integrally with the output portion. The actuator according to claim 1 or 2, wherein the actuator is provided. The force / torque source housing has a flange portion and has a flange portion.
The output portion has a facing portion facing the flange surface of the flange portion.
The first elastic member according to any one of claims 1 to 3, wherein one end is connected to the flange surface of the flange portion and the other end is connected to the facing portion. Actuator. The force / torque source, the transmission control mechanism, and the output unit are connected in series.
The actuator according to claim 4, wherein a plurality of the first elastic members are installed around the transmission control mechanism in a portion sandwiched between the flange portion and the facing portion. The actuator according to any one of claims 1 to 5, further comprising a second deceleration mechanism between the transmission control mechanism and the output unit. Any of claims 1 to 6, further comprising a second elastic member having one end connected to the input portion side of the transmission control mechanism and the other end connected to the output portion side of the transmission control mechanism. The actuator according to item 1. A force / torque source that has a deceleration mechanism and generates a driving force for an output unit that performs an output operation, and the output unit of the driving force that is installed in a transmission path of the driving force generated by the force / torque source. It is an operation control method of an actuator including a transmission control mechanism for controlling transmission to and from a gear.
By the action of the force / torque source driving the output unit, elastic energy is accumulated in the elastic member, and the elastic energy is accumulated.
The transmission control mechanism transmits the driving force of the force / torque source through the gear in the operation in one direction and the reverse direction of the output unit, and inputs the external force in the opposite direction to the output unit. When this is done, the transmission of the driving force to the output unit via the gear is suppressed.
When the transmission control mechanism suppresses the transmission of the driving force to the output unit via the gear, the output unit operates in the opposite direction by the elastic energy stored in the elastic member. A method of controlling the operation of an actuator, which is characterized by having drivability.

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