JPS6134932B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a robot hand, and more particularly to a structure of a hand intended for performing a fitting operation.

Conventionally, as a hand for performing mating,
The structure shown in FIG. 1, which is generally called a compliance mechanism, is known.
This is provided on a plate 4 attached to the tip of an arm 5, with three piano wires 3 intersecting at one point on their extension lines, and a wire parallel to the plate 4 at the other end. A movable plate 2 is provided. Now, install the rod 1 on the movable plate 2 so that its tip is aligned with the intersection of the extended line of the piano wire 3, and insert the rod 1 into the chamfered hole 6. . At this time, when the tip of the rod 1 comes into contact with the chamfered portion of the hole 6, a component force in the direction of arrow 8 is applied to the tip of the rod 1 as a reaction force of the force applied to the arm 5 in the direction of arrow 7. At this time, the movable plate 2 moves in the direction of arrow 8 while remaining parallel to the plate 4, and as a result, the rod 1 moves in the direction where its center line coincides with the hole 6 while remaining parallel to the hole 6. inserted into. In this way, the conventional mechanism called a compliance mechanism can achieve fitting with a simple structure, but it has the following drawbacks.

(1) It is necessary to match the intersection of the tip of the rod and the piano wire, and it is necessary to change the position of the intersection of the piano wire depending on the length of the rod.

(2) In order to generate a component force in the direction of arrow 8 from the force in the direction of arrow 7, it is necessary to greatly chamfer the hole 6.

(3) Since the rod has low rigidity in the direction of insertion, auxiliary support means are required when strong forces are applied in this direction.

The present invention aims to eliminate these drawbacks and achieve smooth fitting.One embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In the figure, the purpose of the robot hand according to the present invention is to fit a rod 10 into a workpiece 9 having a hole 9a. The rod 10 is chucked by a chuck 11 which opens and closes around a shaft 12. This chuck 11 is held by a chuck drive section 13 and is opened and closed by it. This chuck drive section 13 includes
Two elastic leaf springs 15 are fixed to each other by a presser plate 14 and screws 19 so as to be parallel to each other. Furthermore, at the other end of the leaf spring 15,
An intermediate plate 20 is fixed by a holding plate 18 and screws 19. Further, the intermediate plate 20
Two other parallel leaf springs 21 are fixed to the two parallel leaf springs 15 in a direction perpendicular to the two parallel leaf springs 15 . A hand base 22 is fixed to the other two parallel leaf springs 21.
2 is fixed to the arm 23 with a screw 24.

Holes 17 and 17a are provided in the leaf spring 15 and the leaf spring 21 in order to generate two minimum cross-sectional portions A in each of the leaf springs 15 and 21 in the direction in which they are connected as shown. Furthermore, strain gauges 16 and 16a are provided to detect the amount of strain in this minimum cross-sectional portion A. The opposite leaf springs of the leaf springs 15 and 21 have
Strain gauges 16b and 16c are provided at similar positions. The strain gauges are connected to form the well-known bridge circuit shown in FIG.
A constant input voltage is applied between the terminals 25, and an output signal corresponding to the amount of strain of the strain gauge is obtained between the terminals 26. Two bridge circuits are provided, one circuit corresponding to the two leaf springs 15 and the other circuit corresponding to the other two parallel leaf springs 21.

Here, the two parallel leaf springs 15 and the strain gauge provided thereon are provided to exhibit their effect when a force in the direction of the arrow 29 is applied to the rod 10. Two parallel leaf springs 21
The strain gauge provided thereon is provided so as to exhibit its effect when a force in the direction of arrow 28 is applied to the rod 10. Needless to say,
When forces act in both directions of arrows 28 and 29, both act.

Next, referring to FIG. 5, the operation and control method will be described using an example in which a force in the direction of arrow 27 is applied to the rod 10.

In the figure, when the arm is lowered in the direction of arrow 30 and the edge of the rod 10 comes into contact with the chamfered part of the hole 9a, a component force is generated in the direction of arrow 27, and the rod 10, and therefore the chuck 11, are forced to move in the same direction. Force is added. Due to this force, the two leaf springs 15 are deformed into an S-shape with the minimum cross-sectional portion as the bending center, with the two leaf springs 15 having similar shapes. At this time, due to the principle of parallel links, the intermediate plate 20 and the chuck drive section 13 move while maintaining their initial parallel state.
At this time, a compressive force acts on the strain gauges 16 and 16b, and a tensile force acts on the strain gauges 16a and 16c. As a result, a current proportional to the amount of strain flows between the terminals 26 in the bridge circuit shown in FIG.

By detecting this current value, the rod 10
is located on the right side with respect to the hole 9a, and while holding the arm 23 downward in the direction of the arrow 30,
When moving to the left in the direction of arrow 29, the rod 10
While maintaining a state parallel to the hole 9a, the center line thereof moves in a direction that coincides with the hole 9a, and fitting is performed. Here, the operation of detecting the amount of strain and moving the arm, and the operation of slightly moving the parallel spring itself to the left and right are combined, and the fitting is performed extremely smoothly.

Since the operations are similar when a force in the direction of arrow 28 is applied to the rod 10 and when forces in both directions of arrows 28 and 29 are applied simultaneously, the explanation will be omitted.

By performing the fitting using the robot hand having such a structure, the following effects can be obtained.

(1) If there is a large misalignment between the center positions of the rod and the hole to be mated, use a strain gauge to determine the direction of the misalignment, and move the arm in the direction that corrects the misalignment to minimize the misalignment. If they become loose, the center alignment is performed by the position correction function of the parallel leaf springs themselves, so that the fitting can be performed extremely smoothly.

(2) Since each of the parallel leaf springs has two minimal cross-sectional parts, even when the height of the leaf spring is reduced, it can easily be deformed into an S-shape, and the strain gauge described above can generate a large output. As soon as the signal is obtained,
The position of the leaf spring itself can also be easily corrected.

(3) Since the amount of center position deviation in the orthogonal direction can be detected as an independent signal,
The arm can be moved in each direction to adjust its position, allowing for smooth fitting.

(4) Parallel springs generally have low rigidity in the direction perpendicular to the spring and high rigidity in the direction parallel to the spring, so when a large force is applied in the insertion direction of the rod, such as during press-fitting can also be handled without the need for special aids.

As described above, according to the present invention, since two pairs of parallel leaf springs whose movable directions are perpendicular to each other are used,
The relative posture of the rod with respect to the arm is always kept constant, and there is no need to control the rod's posture, and only the movement perpendicular to the rod's insertion direction needs to be controlled, making it possible to correct positional deviations. can be done easily and quickly.

Furthermore, due to the characteristics of the parallel leaf springs, they have high rigidity in the rod insertion direction, and even when receiving a strong force in the rod insertion direction, no special auxiliary means are required and the structure is simple.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional example called a compliance mechanism, Fig. 2 is a front view showing the structure of a robot hand according to an embodiment of the present invention, Fig. 3 is a side view of the same, and Fig. 4 is a parallel view of the robot hand. Diagram 5 showing how to connect the strain gauge attached to the spring part
The figure is a diagram illustrating the operating principle of a robot hand according to an embodiment of the present invention. 11...chuck, 15, 21...parallel spring,
20...Intermediate, 23...Arm, 16,16
a, 16b, 16c...Strain gauge.

Claims (1)

[Scope of Claims] 1. A chuck portion for gripping an article, a pair of leaf springs arranged in parallel with one end fixed to the chuck portion, and an intermediate member fixing the other end of the pair of leaf springs. , a pair of leaf springs arranged in parallel with one end fixed so as to be movable in a direction perpendicular to the movable direction of the pair of leaf springs; an arm fixing the other end of the pair of leaf springs; A robot hand comprising: a strain gauge that detects the amount of strain in a leaf spring; and a control means that controls movement of the arm so that the amount of strain detected by the strain gauge is reduced. 2. The robot hand according to claim 1, wherein each leaf spring is provided with a minimum cross-section portion.