JPH0661714B2 - Robot hand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a robot hand, rough control of large movements is performed by a shape memory actuator made of a shape memory alloy that returns to a previously stored shape when heated above a predetermined temperature, The delicate control of small movements that cannot be performed by the shape memory actuator is operated by a piezoelectric actuator composed of a piezoelectric element that deforms in a certain direction when a predetermined voltage is applied, so that coarse control and fine adjustment can be performed with a simple and small actuator. It becomes possible to perform it quickly and accurately.

[Industrial application field]

The present invention relates to a robot hand that controls an actuator according to a command from a control unit and grasps, conveys, and releases an object, and particularly a robot that uses a small actuator to perform rough control and fine adjustment quickly and accurately. For hand.

A compact, lightweight, multi-degree-of-freedom actuator that excels in power-to-weight ratio like human muscles and is highly flexible when aiming for intelligent or autonomous robots that are expected to be labor-saving devices in all industries. Development is desired.

[Problems to be solved by conventional technology and invention]

FIG. 3 is a configuration diagram illustrating a conventional example of a robot hand,
FIG. 4 is a diagram for explaining a conventional example using a shape memory alloy, and FIG. 5 is a diagram for explaining a conventional example using a piezoelectric element.

FIG. 3 shows various types of conventional robot hands, and FIG. 3 (A) is an example composed of a gear 32 and a rack 31 for converting its force in the arrow direction, FIG. 3 (B). Is an example in which the force of the motor 43 is converted in the direction of the arrow by the worm gear 41 and the worm wheel 42. FIG. 3C shows that the force of the motor 51 with gear is converted in the direction of the arrow by the feed screw mechanism 52. Examples of the above configurations are shown below.

In any case, the embodiment of FIG.
Energy is transmitted to the controls 5 to 5 by a conversion function using mechanical parts such as the gear 32, the worm wheel 42, and the feed screw mechanism 52. Therefore, there is a limit to downsizing of the robot hand, and it is difficult to finely adjust the grasping force when grasping an object.

As one of these solutions, an example in which the actuator 61 is implemented by using a shape memory alloy (hereinafter referred to as SMA) is shown in FIG.

The SMA has undergone shape memory processing in advance, and at any temperature below a certain temperature (this is called the reverse transformation start temperature), the specified temperature (this is called the reverse transformation end temperature)
It has the property of returning to its original memorized form when heated above.

In addition, there are three types of SMA, one-way type, two-way type (reversible type), and omnidirectional type, depending on the presence or absence of re-deformation and the difference in its deformation behavior. Especially, it is used for robot hands. Is currently limited to one-way types.

In the case of the one-way type, since it is not possible to reversibly reciprocate between the prescribed shapes by only heating and cooling, it is used that the recovery force during heating of the SMA exceeds the force required for cooling deformation by several times or more. Then, the auxiliary spring 62 or the like is used in combination as a biasing force for re-deformation.

In the example shown in FIG. 4, the coil-shaped shape memory alloys 61 arranged on the left and right are made to correspond to the two auxiliary springs 62 arranged at the central portion so as to correspond to the respective coil-shaped shape memory alloys 61 on the left and right. The hatched portion at the tip of the leaf spring 63 represents the grasped object.

In the case of the control of this actuator 61, the heating operation can be performed quickly by energizing it, etc., but the cooling deformation operation can be performed quickly even if the auxiliary spring 62 is not used for forced cooling. I can't. Moreover, forced cooling makes it difficult to realize miniaturization.

Moreover, since temperature control is performed, it is not suitable for delicate control. On the other hand, as shown in FIG. 5, when the actuator 71 is formed by using the bending force and the extension force when the piezoelectric element is energized, it is suitable for delicate control, but like the actuator 61 using the SMA. There are various problems such as difficulty in obtaining a large displacement.

[Means for solving problems]

FIG. 1 shows a diagram for explaining an embodiment of the present invention. The robot hand 1 of this embodiment is an actuator 11 using SMA.
And the actuator 12 using a piezoelectric element are combined to form the robot hand 1.

In this embodiment, the auxiliary spring 13 is provided as a bias force when the actuator 11 using the SMA is cooled and deformed, and the sensor 14 is provided for detection when grasping an object.

[Action]

Rough control of large movement is performed with an actuator using SMA that returns to a memorized shape when heated above a predetermined temperature, and delicate control of small movement that cannot be performed by the actuator using SMA is applied in a certain direction when a predetermined voltage is applied. By configuring the actuator using a piezoelectric element made of a deformable piezoelectric element, a small actuator can be used to roughly adjust large movements and finely adjust small movements quickly and accurately. It will be possible.

With this configuration, it is also possible to use the SMA extension and contraction to move the object in the horizontal direction toward the drawing without moving the robot body while slightly grasping the object to be grasped. Becomes

〔Example〕

The gist of the present invention will be specifically described below with reference to the embodiments shown in FIGS.

FIG. 2 shows a diagram for explaining another embodiment of the present invention. still,
The same reference numerals denote the same objects throughout the drawings.

This embodiment shown in FIG. 1 is an actuator using SMA.
This is a case where 11 is combined with an actuator 12 of a bimorph-type piezoelectric element that adjusts the gripping force by the deflection of the piezoelectric element generated when electricity is applied.

On the other hand, FIG. 2 shows an actuator 21 using an SMA, and a laminate for adjusting the gripping force of the tip portion of the hand by expanding the expansion of the piezoelectric element generated when energized with a leaf spring 24 to some extent. Type piezoelectric actuator 22
This is the case when and are combined. In this embodiment as well, the sensor 25 for detecting when an object is grasped is added to the leaf spring 24.

Both the first actuators 11 and 21 of the embodiment shown in FIG. 1 and the embodiment shown in FIG. 2 use SMA deformed into a coil shape, and a large movement is performed by the expansion of this SAM. Once the sensors 14 and 25 detect gripping of the object, the control unit (not shown) controls the SMA so as to maintain this state.

On the other hand, delicate control of small movements that cannot be performed by SMA is performed by the second actuators 12 and 22 using piezoelectric elements. For example, when gripping a fragile object, the first actuators 11 and 21 are operated until lightly gripped, and then the second actuators 12 and 22 are made to finely adjust the gripping force.

In the above case, since control is performed by combining two actuators, special forced cooling is not required when the SMA is cooled and deformed, so that the size can be further reduced.

In addition, the first actuators 11 and 21 using SMA can have a large opening and closing width, and the second actuators 12 and 22 using piezoelectric elements can finely adjust the gripping force.

〔The invention's effect〕

According to the present invention as described above, it is possible to quickly control the opening and closing of the robot hand and realize a robot hand that can be adjusted from a large opening and closing to a delicate gripping force in a more compact size and move the robot body. There is an effect that it is possible to move to a certain extent while holding a grasped object delicately without doing so.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining an embodiment of the present invention, FIG. 2 is a diagram for explaining another embodiment of the present invention, and FIG. 3 is a conventional example of a robot hand. FIG. 4 is a configuration diagram, FIG. 4 is a diagram illustrating a conventional example using a shape memory alloy, and FIG. 5 is a diagram illustrating a conventional example using a piezoelectric element. In the figure, 1 to 7 are robot hands, 11,21,61 are SMAs, 12,22,71 are piezoelectric elements, 13,23,62 are auxiliary springs, 14,25 are sensors, and 24,63,72 are plates. A spring, 31 is a rack, 32 is a gear, 41 is a worm gear, 42 is a worm wheel, 43 is a motor, 51 is a motor with a gear box, and 52 is a feed screw mechanism.

Claims (1)

[Claims] 1. A robot hand for controlling an actuator according to a command from a control unit to grasp, transport, and release an object.
(1) A piezoelectric type comprising a shape memory actuator (11) made of a shape memory alloy that returns to a previously stored shape when heated to a predetermined temperature or higher, and a piezoelectric element that deforms in a certain direction when a predetermined voltage is applied. An actuator (12) is provided, the shape memory actuator (11) and the piezoelectric actuator (12) are combined, and the robot hand (1)
The coarse control of the large movement of the shape memory actuator (1
A robot hand, characterized in that in 1), fine control of small movements is performed by the piezoelectric actuator (12).