JPS6279990A - Robot hand - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a robot hand used in robots 1 to 1 for performing various tasks. The present invention relates to a robot hand that is capable of gripping an object according to the object, and that reduces the amount of force exerted on the object.

(Prior art) When a robot assembles, adjusts, inspects, etc. parts and equipment, the work of gripping the parts and marking the assembly number, and gripping and turning the knobs is done by so-called hands. In such cases, the robot arm can be moved to the assembly or knob position for one of the many objects to be worked on, and the hand can be positioned and taught. When assembling the hand, the position and gripping position of the knob are determined.

However, these positions are dependent on tolerances in the device design, and in relatively large devices, there can be large positional deviations on the order of millimeters between the hand position when the robot is played back and the taught position. If the parts are assembled or the knob is gripped in such a state, an excessive reaction force will be applied to the parts and the knob, and there is a risk that they will be damaged.

In order to correct such a positional deviation, a positional deviation detection means is required, but it is expensive and can only be used under certain special conditions.

For this reason, it is inexpensive and practical to apply a hand with a so-called alignment mechanism that absorbs positional deviation by imitating the reaction force when a component or knob is gripped by the hand.

RCC (ReIl) is a hand with such an alignment mechanism.
A hand called a "lote Center Compliance" hand has been developed. This is configured, for example, as shown in FIG. That is, a gripper 4 is attached to a main body 2 attached to a robot arm 1 via a support 3 made of an elastic member such as rubber, and this gripper 4 grips an insertion part 5. When the tip of the gripper hits the entrance of the hole 7 of the inserted component 6, the gripper 4 moves horizontally due to the reaction force applied to the inserted component 5, and rotates around the remote center 8 near the tip of the inserted component 5. , so that the insertion part 5 is inserted following the hole 7.

[Problem that the invention seeks to solve]

However, since the above-mentioned hand uses a material such as rubber for the support 3, it deteriorates severely over time and has a problem in terms of reliability. Further, when it is desired to transmit a large torque, since the torsional rigidity of the support body 3 is small, a large torsion occurs between the gripper 4 and the main body 2, or the gripper body 2 is damaged. Furthermore, when the hand is used in a horizontal direction, such as when inserting a component into the horizontal hole 7, the gripper 4 tilts due to its own weight, making the work difficult.

[Means for solving problems]

The present invention provides a robot hand that has a degree of freedom in a predetermined plane direction and a degree of freedom to rotate around an axis perpendicular to the plane, in which a gripping mechanism is provided via a compliance mechanism to provide flexibility in the plane direction. is attached to the robot arm, and the compliance mechanism is arranged between an intermediate plate arranged between the robot arm and the gripping mechanism and along the plane, and a compliance mechanism arranged between the intermediate plate and the arm, and a compliance mechanism arranged between the intermediate plate and the arm along the plane a first linear guide mechanism that restricts relative movement only in one parallel axis direction;
A first elastic mechanism is disposed between the intermediate plate and the gripping mechanism, and is arranged between the intermediate plate and the gripping mechanism to bias the intermediate plate to a neutral point in one axis direction allowed by the first linear guide mechanism. a second linear guide mechanism that restricts relative movement only in one axis direction that is parallel to the plane and intersects with the one axis direction allowed by the first linear guide mechanism;
It is characterized by comprising a second elastic mechanism that urges the gripping mechanism to be located at a neutral point in one axis direction allowed by the second linear guide mechanism.

In this case, one axial direction allowed by the first linear guide mechanism and one axial direction allowed by the second linear guide mechanism are made perpendicular to each other, and the spring rigidities of the first elastic mechanism and the second elastic mechanism are It is desirable that the ratio be equal to the ratio of the sum of the weights of the parts of each elastic mechanism that can be displaced in the relevant displacement direction when the arm is used as a fixed point.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 to 3 show the structure of the embodiment.

This robot hand has a degree of freedom in the X-Y plane direction and
The degree of freedom for rotation around two axes perpendicular to the Y plane is shown in the figure. In the figure, 11 is the arm of the robot;
2 is a holder for attaching the hand to the arm portion 11 of the robot; 13 is a first linear guide mechanism; 13a is a sliding body of the first linear guide mechanism 13; 13b is a guide rail for guiding the sliding body 13a; a first spring member (first elastic mechanism); 15 is an intermediate plate; 16 is a central spring support bin;
17 is a second linear guide mechanism, 17a is a sliding body of the second linear guide mechanism 17, 17b is a guide rail that guides the sliding body 17a, 18 is a second spring member (second elastic mechanism), 1
9 is a spring support bottle, 20 is a fixing member, 21 is a gripping mechanism,
21a is a gripping claw, and 22 is an object to be gripped.

In this embodiment, the first. This shows a case where the second linear guide mechanisms 13° 17 are arranged in directions orthogonal to each other, and the holder 12 attached to the tip of the robot arm 11 has the first
A sliding body 13a of the linear guide mechanism is fixed with a screw. The sliding body 13a moves linearly on the guide rail 13b in the longitudinal direction (X direction) of the guide rail 13b, and other movements are restricted. This guide rail 13b is fixed to the intermediate plate 15, and the intermediate plate 1
5, and two spring support pins 19 that are fixed to the holder 12.
Between them are two first spring members 14.14 of the same characteristics.
are attached so as to apply the same tensile force to each other.

Therefore, the intermediate plate 15 has a structure in which it can be elastically displaced relative to the holder 12 only in the longitudinal direction (X direction) of the guide rail 13b.

On the other hand, the sliding body 17a and the guide rail 17b of the second linear guide mechanism 17 are arranged in the direction (Y direction) perpendicular to the movement direction of the first linear guide mechanism 13, and are
It is fixed to the intermediate plate 15 and the fixing member 20. In addition, 18.2 of the second spring members are connected to the first spring member 1.
4, the central spring support pin 16 fixed to the intermediate plate 15 and the two spring support pins 19 fixed to the fixing member 20 are installed so as to apply the same tensile force to each other ( ).

The fixing member 20 includes a gripping mechanism 2 that grips an object 23 to be gripped.
1 is fixed, the gripping mechanism 21 has a structure in which it can be elastically displaced only in the longitudinal direction (Y direction) of the guide rail 17b of the second linear guide mechanism 17 relative to the intermediate plate 15. .

Above, mainly the intermediate plate 15, the first plate. Second linear guide mechanism 13.17, g51. Second spring member 1/1,1
8. A compliance mechanism is constituted by the support bins 16 and 19.

With such a structure, the gripping claws 21 of the gripping mechanism 21
When the gripped object 23 is gripped in a situation where a certain positional deviation exists, the gripping mechanism 21 moves the intermediate plate 15
, the intermediate plate 15 is displaced in the Y direction by the Y direction component of this positional deviation, and the intermediate plate 15 is displaced in the X direction by the X direction component of the positional deviation, and as a result, the gripping mechanism The holder portion 12 is subjected to the positional shift phase stress displacement in both the X and Y directions, and moves to follow the grasped object 23. Here, if all four spring members have the same rigidity, the compliance in any direction on the X-Y plane can be made the same.

In addition, the rotational torque around the gripping axis (Z direction) is received by the first and second linear guide g1 lateral 13.17, and the rigidity of these linear guide mechanisms against movement in directions other than the linear direction can be increased. A fairly large torque can be applied to the object 23. Similarly, X@11. The structure is strong against moments around either Y-axis, so even when gripping in a horizontal direction with the Z-axis horizontal,
The gripping claws 21a can be kept horizontal without being affected by the weight of the gripping mechanism 21. Here, the X axis, YJII
Needless to say, the angle does not necessarily have to be at right angles, and the above effect can be obtained as long as it is within an appropriate range (for example, 10'' to 90 degrees).

Next, an explanation will be given of the operation when the hand is applied to the robot 1 of the present invention for gripping in the horizontal direction.

FIG. 4 is an explanatory diagram of the operation of the mechanical model of the embodiment of the present invention shown in FIGS.
The direction is the same as in Figure 2.

In coordinates 101 and 102, 101 represents the horizontal direction and 102 represents the vertical direction. kl is the stiffness of the first spring member 14, kl
represents the rigidity of the second spring member, and θ represents the rotation angle of the gripping mechanism 21. W2 is the sum of ff1ffl of the grip 'a structure 21, the fixing member 20, the two guide rails 17b of the second linear guide mechanism 17, and the two spring support pins 19, that is, the second is the sum of all the members that can be displaced in the displacement direction (Y direction) related to the spring member 18. Wl is the two sliding bodies 17 of the second linear guide mechanism 17;
a1 intermediate plate 15, central spring support bin 16, and two guide rails 13b1 and 2 of the first linear guide mechanism 13
represents the sum of ff1ffi of the second spring members in one day.

Therefore, Wl+W2 is the first
The sum of the weights δ1 of all members that can be displaced in the displacement direction (Y direction) related to the spring member 14 is shown.

In FIG. 4, the horizontal and vertical components of the displacement of the gripping center O of the gripping mechanism 21 are U+, respectively.

Assuming U2, it is expressed by the following formula.

...(1) Furthermore, the compliance C(θ) when a force is applied to the gripping claw 21a in the direction of the coordinate axis 101 is C(θ) = 1
/2(k, sin 2θ+ 2CO82θ)...(
2) It is expressed as

From formula (1), the first spring member 14 and the second spring member 1
The stiffness ratio of 8 to k+/2= (Wl +W2)/
By choosing W+, U+ = O, U regardless of θ
2 = -Wl/2kHz, and the gripping center O of the gripping mechanism 21 is always -W+ in the vertical direction from the center position of the holder 12.
It can be set at a position displaced by /2 kHz.

Therefore, even in the case of horizontal gripping, if the position of the gripping claw 21a of the gripping mechanism 21 is taught with respect to the object to be gripped 22 as in a normal robot device, regardless of the rotation angle of the gripping mechanism 21. Positioning can be performed with good reproducibility.

However, in this case, the compliance C(θ) is the gripping machine M4
It changes depending on the rotation angle of 21. However, as a result of various prototypes of the present invention, the ratio of (Wl +W2)/W1 was 1.
1 to 1.2, and it has been confirmed that there is no negative impact on the actual assembly or rotation of the knob.

Of course, in the case of gripping only in the vertical direction, the spring rigidities of the first J3 and second spring members 14 and 18 may be set equal to + and kl.

In addition, in the above embodiment, the first. The second linear guide mechanism 13.17 can be selected from various types such as a sliding type, a rolling type, and other structures. Further, the number of points to be used is also arbitrary. Further, the first and second spring members 14 and 17 are not limited to coil springs as in this embodiment, but are used between the holder 12 and the intermediate plate 15 and between the intermediate plate 15 and the fixed plate 20. Various structures can be considered, such as a structure in which a leaf spring is installed between them.

(Effects of the Invention) As explained above, since the robot hand of the present invention is configured to be able to freely displace elastically within a plane perpendicular to the gripping axis, a slight reaction force applied to the gripping claw can cause The gripping claws or the assembled parts gripped by the gripping claws are displaced.Therefore, even if there is a slight positional deviation between the assembled parts and the assembly, it can be easily assembled, and the gripped parts such as knobs can be easily assembled. It is possible to grasp and manipulate objects without applying excessive force.

In addition, the linear guide mechanism is structured to resolve misalignment into displacements in the direction of the two wheels that intersect with each other, so it is robust against translational forces other than those in the direction of the two wheels, and is capable of transmitting large torque. It is also possible to keep the hand horizontal and make highly accurate positioning.

Therefore, if the robot hand of the present invention is used especially for assembling parts that are often gripped in the horizontal direction or for adjusting and inspecting equipment,
These operations can be automated with high reliability without damaging the gripped object, and have the advantage of increasing efficiency and saving labor.

[Brief explanation of drawings]

1 is a side sectional view of an embodiment of the present invention, ``FIGS. 2 and 3 are sectional views taken along the line II--II in FIG.
(2) A sectional view taken in the direction of arrows, FIG. 4 is an explanatory diagram showing a dynamic model of the operation of the present invention, and FIG. 5 is an explanatory diagram showing the configuration of a conventional example. 11...Robot arm part, 12...
・Holder, 13...First linear guide mechanism, 13
a...Sliding body, 13b...Guide rail, 14...First spring member (first elastic mechanism)
, 15... Intermediate plate, 16... Central spring support pin, 17... Second linear guide mechanism, 18... Second spring member ( second elastic mechanism)
, 19... Spring support bin, 20... Fixing plate, 21... Grasping mechanism, 22... Grasping object.

Claims (2)

[Claims] (1) In a robot hand that is attached to the tip of a robot arm and has a degree of freedom in a predetermined plane direction and a degree of freedom to rotate around an axis perpendicular to the plane, to provide flexibility in the plane direction. a gripping mechanism is attached to the arm via a compliance mechanism;
The compliance mechanism includes an intermediate plate disposed between the arm and the gripping mechanism and along the plane, and is disposed between the intermediate plate and the arm, and is capable of relative movement of the intermediate plate and arm only in one axis direction parallel to the plane. a first linear guide mechanism that regulates the movement of the intermediate plate, a first elastic mechanism that urges the intermediate plate to be positioned at a neutral point in one axis direction allowed by the first linear guide mechanism, and a second linear movement disposed in between, which restricts relative movement of the gripping mechanism and the intermediate plate only in one axis direction that is parallel to the plane and intersects with the one axis direction allowed by the first linear movement guide mechanism; A robot hand comprising a guide mechanism and a second elastic mechanism that urges the gripping mechanism to be positioned at a neutral point in one axis direction allowed by the second linear guide mechanism. (2) The one-axis direction allowed by the first linear guide mechanism and the one-axis direction allowed by the second linear guide mechanism are orthogonal to each other, and the springs of the first elastic mechanism and the second elastic mechanism 2. The robot hand according to claim 1, wherein the rigidity ratio is equal to the ratio of the sum of weights of parts movable in the relevant displacement direction of each elastic mechanism when the arm is a fixed point.