JPH0319783A - Workpiece holding mechanism - Google Patents

Abstract

PURPOSE:To form a driving source, which drives fingers, in a relatively small size with a weight of a workpiece supported on the upper surface of the finger by placing a flanged part on the finger at the time of moving by an arm part in a condition that a lower portion of the flanged part is held by the finger. CONSTITUTION:Since fingers 6, 6 in a hand part 3 hold the lower of a flanged part 11 in an workpiece 9, its flanged part 11 is placed on the fingers 6, 6, and weight of the workpiece 9 is supported not by clamping force of the fingers 6, 6 but by their upper surfaces. Accordingly, the clamping force of the fingers 6, 6 is required only to a degree, in which the workpiece 9 is not displaced while an arm part 1 is in motion, and a driving source, which drives the fingers 6, 6, can be relatively small.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a work holding mechanism in a so-called robot.

(b) Conventional technology When a workpiece is gripped and transported by the fingers of the hand section attached to the arm section, the fingers are moved horizontally from side to side, and the workpiece is gripped between the fingers from left and right. I can think of 戊. However, in such a structure, the workpiece is gripped between the fingers from the left and right, so in order to securely grip the workpiece, a sufficiently large gripping force must be applied to the fingers. The drive source must be sufficiently large. However, if the motor that drives the fingers is made larger, the entire arm portion becomes larger and its weight increases, resulting in a problem that the payload of the workpiece holding mechanism becomes smaller.

Additionally, when a hand attached to an arm is used to grab a workpiece and transfer it onto a table, etc., conventionally the height position of the table is taught to the control unit that controls the arm in advance. The method is important. however,
In the peeling method, it is necessary to accurately measure the height of the platform in advance, which is troublesome. Furthermore, in the case of a type in which the arm is mounted on a moving trolley, changes in the tire diameter of the moving trolley can be avoided. There is a possibility that the positional relationship in the height direction may be shifted due to such reasons, making it impossible to perform reliable gripping and placing operations.

(c) Problems to be Solved by the Invention The present invention provides a workpiece holding mechanism that is small and lightweight, and can perform gripping and placement operations reliably.

(2) Means for Solving the Problems The first feature of the workpiece holding mechanism of the present invention is that it includes a workpiece having a flange, a hand portion having fingers for holding the lower portion of the flange of the workpiece, and a hand portion for holding the workpiece. The present invention is characterized in that when the arm section is moved by the arm section 9 and the lower part of the flange is held by the fingers, the flange section -12 is placed on the fingers.

Further, the second structure includes a hand section that holds a workpiece, a weight sensor attached to the hand section that detects the weight of the workpiece, an arm section that moves the hand, and an arm section that receives information from the weight sensor. The controller includes a control unit that controls the operation of the hand section and the arm section, and when the workpiece is placed on the table, the control section detects that the workpiece is placed on the table due to a decrease in the weight of the workpiece as detected by the weight sensor. It is characterized by making a judgment.

(e) Effect According to the first precept, the fingers of the hand hold the lower part of the flange of the workpiece, so the flange of the workpiece rests on the second finger of the finger.
The weight of the workpiece is supported by the fingers and not by their gripping force.

According to the second precept, when placing the workpiece on the table, it is determined that the workpiece is placed on the top of the table due to a decrease in the amount of the workpiece M as detected by the weight sensor.

(f) Example 1 to 5 show the first and second structures 3 of the present invention. 4 An example of the present invention is shown below.

FIG. 1 is a schematic diagram of a robot device in which the invention is implemented.

Here, 1 is an arm part, 3 is a hand part provided at the tip of arm part 1, 4 is a weight sensor, and 2 is a control that receives a signal from this weight sensor 4 and controls the operation of arm part 1 and hand part 3. This is a Luli control circuit as a part.

FIG. 2 is a perspective view showing the hand section 3. FIG. The hand section 3 is constructed by attaching two fingers 6, 6 that are opened and closed by a drive section (not shown, such as a moke) to a support body 5 to which an auxiliary finger 7 is fixed. Also, two fingers 6,6
A total of three weight sensors 4, 4, 4 are attached to two surfaces of each of the auxiliary fingers 7 and 7. These weight sensors 4, 4.4 are made of, for example, strain gauges or pressure-sensitive conductive rubber, and when the finger 6.6 is held horizontally, the three weight sensors 4, 4.4 are at the same height. It is installed so that

FIG. 3 is a side view showing a state in which the workpiece 9 is gripped by the hand section 3, and FIG. 4 is a front view thereof. Work 9 is
The cylindrical part is composed of a cylindrical part]O and a flange part 11 provided on the periphery of the upper end of the cylindrical part, and depending on the case, another material is placed on the upper surface of the flange part and is conveyed together with the workpiece 9.

The hand portion 3 grips the workpiece 9 by holding the cylindrical portion 10 below the collar portion 1 of the workpiece 9 with the two fingers 6, 6. At this time, the workpiece 9 is lifted with the collar part 11 placed on two surfaces of the fingers 6, 6 and the auxiliary finger 7, and the weight of the workpiece 9, that is, the weight of the workpiece 9, is
, 6 and the two surfaces of the auxiliary finger 7, the weight sensors 4, 4 .
Supported through 4. In this state, the fingers 6, 6 are lightly holding the cylindrical portion 10 to the extent that the work 9 does not shift. At this time, the weight of the workpiece 9 can be measured by the sum of the outputs of the three weight sensors 4, 4.4.

FIG. 5 is a flowchart showing the operation of placing the work on the table, and the operation will be explained below using this flowchart.

First, the workpiece 9 is gripped by the hand portion 3 and positioned above the positioning point. Next, in step (2), the arm portion 1 starts lowering. In step (2), the control circuit 2 obtains signals from the weight sensors 4, 4.4, detects the weight of the workpiece 9, and determines whether the child IYi is larger than a predetermined threshold value.

If the f-direction is greater than the threshold f1k, it is determined that the workpiece 9 is not yet on the platform, and the process is performed.
repeat. If the detected force becomes smaller than the threshold value, it is determined that the workpiece 9 is on the second floor of the table at that point, and the lowering of the arm portion 1 is stopped in step (3). After that, open the fingers 6.6 to release the workpiece 9, and then
is pulled out from below the flange 11 of the work 9.

At this time, as is clear from the operating principle, the fingers 6, 6 must not grip the workpiece 9 too strongly. The gripping force of the fingers 6, 6 is such that the workpiece 9 does not shift when the arm part 1 moves I1 = is the cylindrical part 10
It is good to have enough force to slide on the surface.

According to this structure, the fingers 6, 6 of the hand section 3 touch the workpiece 9.
In order to hold the lower part of the flange 11 of the workpiece 9, the flange 11 of the workpiece 9 rests on the finger 6.6, and the weight of the workpiece 9 is not caused by the gripping force of the fingers 6, 6, but by the upper surface of the finger 6.6. Supported.

Therefore, the gripping force of the fingers 6, 6 may be such that the workpiece 9 does not shift while the arm section 1 is moving, and the drive source for driving the fingers 6, 6 may be relatively small. In addition, according to this precept, when placing the workpiece 9 on an old surface, the weight sensors 4 and 4 are
, 4, it is determined that the workpiece 9 is on the second part of the platform, so there is no need to take the trouble of accurately measuring the height of the platform in advance, and furthermore, the arm part 1 can be mounted on the movable cart. Even when used as a mobile cart, the positional relationship in the height direction will not shift due to changes in the tire diameter of the mobile cart. Therefore, the arm portion 1 and the hand portion 3 can be made smaller and lighter, and the gripping and placing operations can be performed reliably.

FIGS. 6 to 13 show other embodiments of the first structure of the present invention. Incidentally, here, the same reference numeral 7 8 is given to the same or corresponding parts as in the previously described embodiment.

6 and 7 show the work 9, FIG. 6 is a perspective view,
FIG. 7 is a sectional view. The workpiece 9 is composed of a cylindrical part 0 and a flange 1 provided at the periphery of the second end of the cylindrical part.

FIG. 8 is a perspective view of the hand portion 3 viewed from below. Here, 5 is a support body, which is provided with two fingers 6, 6 that are opened and closed by a motor 2 serving as a drive unit. 13,]
/I is a light projecting means and a light receiving means provided on the lower surface of each of the fingers 6, 6, and these constitute a position sensor that detects the position of the workpiece 9 as viewed from the hand section 3. 15.1
A microswitch 5 is provided on the inner surface of the fingers 6, 6 and serves as a contact sensor that detects contact between the fingers 6, 6 when the work 9 is held between them. Note that the hand portion 3 in this embodiment is not provided with the auxiliary finger 7 and the weight sensor 4 that were provided in the previous embodiment.

The gripping operation of the workpiece 9 by the hand section 3 will be described in detail below with reference to FIGS. 9 to 13.

When attempting to grasp the workpiece 9 placed on the second side of the table 16, first, the fingers 6.6 are below the flange 11 of the workpiece 9,
Moreover, the arm portion 1 is controlled so as to be located above the upper surface 17 of the table 16. Then, with the fingers 6 and 6 spread, the hand section 3 is directed toward the workpiece 9, and the hand section 3 is moved toward the workpiece 9 as it is. (FIG. 9) During the movement, light is emitted from the light projecting means 13 toward the light receiving means 14 to activate the position sensor. and,
When the cylindrical part 10 of the workpiece 9 blocks the light and the light receiving stage 14 no longer receives the light from the light emitting stage 13, it is determined that the hand part 3 is in a position where it can grip the workpiece 9, and the arm Stop part 1. (FIG. 10) At that position, the motor 12 is driven to close the fingers 6, 6, and the cylindrical portion 10 of the workpiece 9 is gripped by the fingers 6.6. (
(Figs. 11 and 12) At this time, as described in the previous embodiment, the gripping force of the fingers 6.6 is such that when the workpiece 9 is fixed, the movement of the arm portion 1 causes the fingers 6, 6 to move around the cylinder. Part】O
Therefore, even if the arm part 1 is raised in this state, the fingers 6, 6 will slip on the cylindrical part 10 of the workpiece 9, and the workpiece 9 will not be lifted immediately. Then, the hand part 3 is raised and the fingers 6, 6 are attached to the flange part 1 of the workpiece 9.
The workpiece 9 is lifted only after the collar portion 11 comes into contact with the lower surface of the finger 1 and the collar portion 11 is placed on the upper surface of the fingers 6, 6. (Fig. 13) Also in this embodiment, the fingers 6, 6 of the hand section 3 are connected to the workpiece 9.
In order to hold the lower part of the flange 11 of the workpiece 9, the flange 11 of the workpiece 9 rests on the fingers 6, 6, and the weight of the workpiece 9 is not dependent on the gripping force of the fingers 6, 6. supported by surfaces. Therefore, the gripping force of the finger 6.6 is the movement r4 of the arm
It is sufficient that the workpiece 9 does not shift, and the drive source for driving the fingers 6, 6 may be relatively small. Therefore, the arm portion 1 and the hand portion 3 are small and lightweight, and can perform gripping and placement operations reliably.

(G) Effects of the Invention According to the first principle of the present invention, the weight of the workpiece is supported by the two surfaces of the fingers, not by the gripping force of the fingers, so the driving source for driving the fingers is relatively small. It can be something. In addition, according to the second structure, when placing the workpiece on the table, it is determined that the workpiece is on the top of the table based on the detection result of the weight sensor, so the height of the table can be accurately determined in advance. Furthermore, even if the arm is mounted on a movable trolley, the positional height in the height direction will not shift due to changes in the tire diameter of the movable trolley.

Therefore, it is possible to provide a work holding mechanism that is small and light 111 and that can perform gripping and placement operations reliably.

[Brief explanation of the drawing]

1 to 5 show embodiments of the first and second structures of the present invention, FIG. 1 is a schematic diagram of a robot device in which the invention is implemented, FIG. 2 is a perspective view of the hand section, and FIG. 3 is a side view showing the state in which the workpiece is gripped, and FIG. 4 is a front view 11 showing the state in which the workpiece is gripped.] FIG. 2 and FIG. 5 are flowcharts showing the operation of placing the workpiece on the table. 6 to 13 show other embodiments of the first structure of the present invention, FIG. 6 is a perspective view showing the workpiece, FIG. 7 is a sectional view showing the workpiece, and FIG. 8 is a hand section. 9, 12, and 13 are side views showing the state in which the workpiece is held together, and FIGS. 10 and 11 are top views showing the state in which the workpiece is held in place. . 1... Arm part, 2... Control circuit (control part), 3...
- Hand portion, 4... Weight sensor, 6... Finger, 9... Workpiece, 11... Collar section.

Claims (2)

[Claims] (1) Consisting of a workpiece having a flange, a hand portion having fingers for holding the lower portion of the flange of the workpiece, and an arm portion for moving the hand, the lower portion of the flange is held by the fingers. When moving by the arm part in the above condition,
A work holding mechanism characterized in that the collar portion is placed on the finger. (2) a hand section that holds a work; a weight sensor attached to the hand section that detects the weight of the work; an arm section that moves the hand; and a hand section that takes in information from the weight sensor; The control unit includes a control unit that controls the operation of the arm unit, and when the workpiece is placed on the table, it is determined that the workpiece has been placed on the table based on a decrease in the weight of the workpiece as detected by the weight sensor. Work holding mechanism.