JPS6130878B2 - - Google Patents

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a support device that supports a second member via an elastic body supported by a first member, and particularly relates to a support device that supports a second member via an elastic body supported by a first member. This relates to the structure of an elastic body.

(2) Background of the technology In recent years, industrial robots have been introduced on factory assembly lines to automate the manufacturing of various products. When such industrial robots are used to perform fitting fitting work in which parts are inserted into holes, it is necessary to accurately align the fitting parts with each other in the fitting work where fitting tolerances are in the micron level. If it is not done properly, the insertion work will not be carried out smoothly and there is a risk of damage to the member. Therefore, there is a need for a robot that can easily control positioning in order to smoothly accomplish highly accurate fitting work.

(3) Problems with the prior art The fitting robots used in the past have a hand at the tip of the arm that grasps the component to be inserted, and by horizontal movement of the arm, the arm positions the component over the hole to be inserted, and then the arm vertical movement of the hole causes the member to fit into the hole. In conventional robots, the hand is rigidly fixed to the tip of the arm, and if the positions of the members to be fitted are even slightly misaligned, insertion becomes difficult and the members may be damaged. Therefore, a highly accurate control mechanism is required to control the positioning of the arm, making the robot expensive.

(4) Purpose of the Invention The present invention has been made in view of the drawbacks of the prior art described above, and provides a support device that can easily and reliably accomplish fitting work without requiring high-precision control for fitting positioning. The purpose is to provide.

(5) Structure of the Invention This object is a support device that supports a second member via an elastic body supported by a first member, wherein one end of the elastic body is connected to the first member. a pair of first parallel leaf springs that are connected, a pair of second parallel leaf springs that have one end connected to the second member, and the other end of the first parallel leaf spring that is connected;
and a connecting member to which the other end of the second parallel plate spring is connected to be perpendicular to the displacement direction of the first parallel plate spring, the first member or the second member, and the elastic body. a cross shape that is provided at the connection portion of and is displaced in a direction perpendicular to the direction of inclination of the second member with respect to the first member and the direction in which the first parallel leaf spring and the second parallel leaf spring are displaced; This is achieved by providing a support device characterized in that it comprises a leaf spring.

(6) Embodiments of the Invention FIG. 1 is a perspective view of an example of an elastic body (hereinafter referred to as mechanical compliance mechanism) of a support device according to the present invention. This compliance mechanism is a parallel spring assembly 3, and is composed of two sets of parallel leaf springs 1 and 2 that are movable in the X direction and the Y direction, which are orthogonal to each other. Each of the parallel leaf springs 1 and 2 is composed of two parallel leaf springs facing each other. For example, when a force is applied in the Y direction, the parallel leaf spring 2 is displaced as shown by the dotted line in the figure.

An example of a robot 4 using such a parallel leaf spring composition 3 is shown in FIG. A parallel leaf spring assembly 3 is fixed to the tip of the arm 5, and a hand 6 is attached to the lower end thereof. The arm 5 can be rotated forward and backward as shown by the arrow E, and can be extended and contracted as shown by the arrow F, and the hand 6 grasps the round bar 7 at a predetermined position above the hole 9 of the member 8 into which it is to be inserted. move it to the position
Next, the round bar 7 is inserted into the hole 9 by vertical displacement of the arm 5 in the direction of arrow G. A chamfer 10 consisting of a tapered surface is provided at the entrance periphery of the hole 9. If the alignment between the round bar 7 and the hole 9 is misaligned within the range of the chamfer 10 (FIG. 3), when the arm 5 is lowered, the round bar 7 will come into contact with the tapered surface of the chamfer 10. When the arm 5 is further lowered, a force in the H direction is applied to the round bar 7, and the parallel spring assembly 3 responds accordingly.
Forces are applied in the horizontal direction in the X direction and the Y direction depending on the position of the deviated position. Therefore, the parallel spring assembly 3 is displaced in the X direction and the Y direction (FIG. 4), and the round bar 7 slides on the tapered surface of the chamfer 10 and fits into the hole 9.

Positioning control of the arm 5 according to the amount of displacement of the parallel spring assembly 3 will be described below. A strain gauge 11 is attached to each leaf spring of the parallel spring assembly 3 (fifth
figure). When a force is applied to a parallel spring and the spring is deformed, the moment distribution is maximum at the ends of each leaf spring and minimum at the center, so the strain gauge 11 should be attached at the top or bottom end of each leaf spring. desirable.
In FIG. 5, strain gauges are attached to four locations on the top, bottom, left and right of each leaf spring. As shown in FIG. 6, a total of eight strain gauges may be attached at four locations on the upper, lower, left and right sides of the surface of each leaf spring, and at four locations on the back surface thereof.
11a to 11h indicate surface strain gauges; 11
a' to 11h' respectively indicate strain gauges on the back side thereof. Strain gauges on the front and back surfaces of the facing leaf springs at corresponding positions (for example, 11a and 11e' or 11f and 1
1b' etc.) measure the same amount of strain. Such a strain gauge measures the amount of strain in each leaf spring and detects the component forces in the X and Y directions that are applied to the parallel spring assembly.Since these component forces correspond to the amount of displacement of each parallel spring, the strain The amount of displacement of the parallel spring assembly in the X direction and the Y direction can be determined by the gauge. Examples of circuits for obtaining an output according to resistance changes of strain gauges are shown in FIGS. 7 to 9. Figure 7 shows a bridge circuit using four strain gauges, and Figures 8 and 9 show a bridge circuit using four strain gauges.
The figures show bridge circuits using 8 and 16 strain gauges, respectively. The greater the number of strain gauges, the more resistance changes are cumulatively added, and the influence of temperature differences depending on location is reduced, which improves the reliability of measurement. FIG. 10 is a perspective view of an example in which a parallel spring assembly 3 equipped with a strain gauge is applied to a robot 4 having a drive mechanism for driving an arm 5 in the X direction, Y direction, and Z direction.
FIG. 1 is a circuit diagram of X and Y direction drive control via strain gauges. When the arm 5 is moved to a predetermined position according to a preset position signal of the arm 5 and the fitting work is performed by the robot 4, if the parallel spring assembly 3 is displaced in the X direction and the Y direction due to misalignment of the fitting position. Signals a and b corresponding to this amount of displacement are obtained via the aforementioned bridge circuit. The displacement signals a and b of the parallel spring assembly are amplified by amplifiers 40 and 41 for increasing the gain, and then sent via the switching circuit 13 (at this time, the switch of the switching circuit 13 is set to the dotted line position) to the mounting position of the strain gauge, The signals are corrected by a compensation circuit 14 that corrects signal errors due to temperature and the like, and are further input to an X-direction drive control circuit 16 and a Y-direction drive control circuit 17 via a current amplifier 15, respectively. Each drive control circuit 1 in the X direction and Y direction
6 and 17 drive the X-direction drive device 18 and the Y-direction drive device 19 in a direction that makes the displacement amount of the parallel spring assembly 3 in the X direction and Y direction zero, and the arm 5 is moved to the displacement amount of the parallel spring assembly. Feedback control is performed accordingly. The arm 5 is positioned based on the displacement signal of the parallel spring assembly when a new round bar is transferred by the arm 5, and the arm position based on the preset position signal is corrected according to the displacement amount, that is, the positional deviation. Feedback control may be performed as shown in FIG. When moving the arm based on the initial setting signal, the central control unit (CPU) 12 sends predetermined position signals e and f in the X and Y directions, and this and the arm's position in the X and Y directions are transmitted. A drive control circuit 16 in the X and Y directions via a compensation circuit 14 and a current amplifier 15 compares the current position signals c and d from a detector (not shown) that detects the current position and sets the difference to zero. 17 for each drive device 1
8 and 19 to move the arm 5 to a predetermined position. At this time, the switch in the switching circuit 13 is connected to the solid line position by the switching control control line 42. If the position of the round bar and the hole deviates greatly beyond the range of chamfering, the CPU 12 determines this based on the current position signals c and d, and sets the switching circuit 13 to the solid line side via the control line 42 to the first position. The arm may be driven based on the setting signal. In this way, the arm is moved using rough positioning control to align the round bar and hole within the chamfering range, and then the round bar and hole are accurately aligned based on the amount of displacement of the parallel spring assembly. The position of the arm can be feedback-controlled so that the

Another example of a mechanical compliance mechanism is shown in the twelfth example.
As shown in the figure. A cross spring 20 consisting of a cross-shaped plate spring is integrally formed on the lower surface of a parallel spring assembly 22 consisting of an X-direction parallel spring 1 and a Y-direction parallel spring 2. 21 is a connecting rod for connecting the hands. The connecting rod 21 can be tilted in all directions with respect to the vertical axis (longitudinal axis) of the parallel spring assembly by the action of the cross spring 20, and can be tilted in the Z-axis direction (vertical direction).
It can also be displaced. When performing fitting work using such a compliance mechanism, the 13th
As shown in the figure, when the axis 60 of the robot's arm 5 is deviated from the axis 50 of the hole 9 and is inclined, when the arm 5 is lowered, the hand 6 first
The round rod 7 held by the hole 9 comes into contact with the tapered surface of the chamfer 10 of the hole 9. When the arm 5 is further lowered, the parallel spring assembly 22 is deformed (FIG. 14), the axis 60 of the arm 5 and the axis 70 of the hand 6 are displaced parallel to each other, and the round bar 7 is lowered along the chamfer 10. do. Arm 5
The round bar 7 is inserted into the hole 9 to a position corresponding to the clearance between the round bar 7 and the hole 9 while the axis 60 of the hand 6 and the axis 70 of the hand 6 are in a parallel state (FIG. 15). When the arm 5 is further lowered, the shaft 70 of the hand 6 is inclined with respect to the shaft 60 of the arm 5 due to the action of the cross spring 20 (see FIG. 12) on the lower surface of the parallel spring assembly 22, and the round bar 7 is moved into the hole 9. is inserted into the shaft 7 of the hand 6.
0 is oriented in a direction that gradually coincides with the axis 50 of the hole 9, and the fit between the round bar 7 and the hole 9 is achieved (16th
figure).

FIG. 17 shows an example of attaching a strain gauge to detect the displacement amount of the inclination angle of the hand with respect to the arm based on the deformation of the cross spring 20. The cross spring is provided mainly for the purpose of absorbing and correcting the relative inclination between the axis of the insert and the axis of the hole into which it is inserted, thereby preventing strain during the insertion operation. Therefore, by installing a force detector (or displacement detector) such as a strain gauge at the part of the cross spring that deforms when mating, and measuring the amount of deformation, it is possible to determine the tilt (angle) of the shaft between the objects when mating. deviation)
In addition to knowing the extent of the inclination, it is also possible to reduce the relative inclination angle between the shafts to almost 0 by providing a mechanism to correct the inclination on the robot side or the object to be fitted and feeding back the detector signal. It is possible to maintain a smooth mating operation. When a bending moment is applied to a cross spring, the maximum stress occurs at the center of the cross spring, so it is desirable to attach a strain gauge close to the center in order to measure shaft displacement with high sensitivity. Furthermore, in order to compensate for the temperature and improve the S/N ratio, strain gauges 23a to 23h are placed on the front and back of each of the four pieces A, B, C, and D of the cross spring as shown in Figure 17.
and 23a' to 23h' can be attached to form a bridge circuit as shown in FIG. A
In order to obtain an output corresponding to the moment Ma of the piece, strain gauges 23c and 23 are used as R ₁ , R ₂ , R ₃ , and R ₄ .
c', 23d, and 23d', and in order to obtain outputs corresponding to the moments M _b , M _c , and M _d of the B piece, C piece, and D piece, R ₁ , R ₂ , R ₃ , and R ₄ are used, respectively. Strain gauges 23a, 23a', 23b, 23 attached to each piece as
b' (B piece): 23g, 23g', 23h, 23
h' (C piece); and 23e, 23e', 23f, 2
3f' (D piece) should be connected.

By performing simple calculations using the outputs of the four detectors of the cross spring and the outputs of each detector of the parallel spring assembly, the X, Y, and Z values at the tip of the hand can be determined.
The force in the direction and the moment about the X and Y axes can be calculated. As shown in Fig. 19, the moments of each piece of the cross spring are M _a , M _b , M
If _c and M _d are the moments detected by the parallel springs in the X and Y directions, M _e and M _f , the following equation holds approximately.

_{M a} =M _X + _{aF Z + lF Y M b} =M _{Y −aF Z −lF X M c = M Y,} where F _X , F _Y , F _Z are the forces in the X, Y, and Z directions applied to the tip of the robot hand: M _X , M _Y are the moments in the X and Y directions applied to the tip of the robot hand: l
is the distance between the center of the cross spring and the tip of the hand; n, m is the distance between the center of the parallel spring acting in the X and Y directions and the detector; a is the distance between the center of the cross spring and the detector. The direction of each moment is shown in FIG.
_{If we transform the above equation , M _ _ _} M _f /m F _Z =M _a - M _c /2a or M _d - M _b /2a, and all the forces and moments in each direction at the tip of the hand can be calculated using the output of the detector.

By providing a mechanism for correcting inclination on the robot side or the fitted object side, the M of the above calculation result can be reduced.
By feeding back _X and M _Y to each tilting motion of the robot, the fitting operation can be performed while the tilting is maintained at approximately zero. For example, as shown in FIG. 10, when a robot having degrees of freedom in two orthogonal axes, an X-direction joint 30a and a Y-direction joint 31a, performs a fitting operation at the tip of the arm 5, a signal of _M If a signal of _M The relative inclination can be corrected by rotation by the directional drive device 31. Of course, it is also possible to correct two axes at the same time. A block diagram of the control system in this case is shown in FIG. Each piece A, B of the cross spring 20,
The signals from the strain gauges attached to C and D are sent to amplifier 2.
4, the arithmetic circuit 25 outputs signals corresponding to _M.sub.X and _M.sub.Y. The signals corresponding _{to M}
0, 31 (Fig. 20) and each joint 30a, 3
Correct the tilt by rotating 1a. At this time, X
Rotation of the joints 30a, 31a in the Y-direction and the Y-direction causes displacement in parallel to the tip of the arm, but this can be corrected by output feedback from the strain gauges attached to each of the parallel springs.

Another example of mounting the cross spring 20 is shown in FIGS. 22 to 24. A rotating shaft 32 is provided at the end of each leaf spring constituting the cross of the cross spring 20 in the same direction as its longitudinal direction, and is attached to the wall surface of the parallel spring assembly 22 via a bearing 33. With this configuration, the deformation of each piece of the cross spring will not affect another leaf spring in the orthogonal direction and cause twisting, and the strain gauge of each piece will not be affected by another leaf spring in the orthogonal direction. The component force applied to each piece can be detected independently without the need for any other force, which improves the reliability of the measurement of M _X and M _Y .

(7) Effects of the Invention As explained above, in the present invention, a mechanical compliance mechanism is provided at the joint between the arm and hand of the robot to enable displacement such as positional and angular deviation of the hand relative to the arm. Therefore, when performing fitting work, even if the fitting positioning control is rough, smooth fitting work can be achieved, damage to parts due to misalignment can be prevented, and there is no need for a highly accurate and expensive positioning control mechanism. do not. The support device according to the present invention includes two sets of parallel leaf spring assemblies made up of leaf springs parallel to each other so as to be displaced in the X and Y directions perpendicular to each other, and further provided in the Z direction and the Z direction perpendicular to the X and Y directions. Since it is equipped with a cross-shaped leaf spring that can tilt in the X and Y axis directions, it is possible to absorb five force vectors independently, and when used as a robot, there is no unnecessary rocking motion. The mating work can be performed without any problems.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a parallel spring assembly according to the present invention;
FIG. 2 is a perspective view of the robot according to the present invention, FIGS. 3 and 4 are explanatory diagrams sequentially showing the fitting operation by the robot according to the present invention, and FIG. 5 is a parallel spring assembly according to the present invention. Figure 6 is a perspective view of another example of strain gauge attachment, and Figures 7, 8, and 9 each show a bridge circuit for obtaining strain gauge output. A circuit diagram showing another example, FIG. 10 is a perspective view of the robot according to the present invention, FIG. 11 is a control circuit diagram of the robot in FIG. 10, and FIG. 12 is a diagram of another example of the compliance mechanism according to the present invention. A perspective view, FIGS. 13 to 16 are explanatory diagrams sequentially showing fitting work by a robot using the compliance mechanism shown in FIG. 12, and FIG. 17 shows an example of pasting a strain gauge on a cross spring. A perspective view, FIG. 18 is a block circuit diagram for obtaining strain gauge output, FIG. 19 is an explanatory diagram showing the state of moment applied to the compliance mechanism according to the present invention, and FIG. 20 is another diagram of the robot according to the present invention. 21 is a control circuit diagram of the robot shown in FIG. 20, FIG. 22 is a perspective view showing an example of mounting the cross spring according to the present invention, and FIGS. 23 and 24 are respectively shown in FIG. 22. FIG. 3 is a plan view and a side view of a cross spring. 1, 2...Parallel spring, 3...Parallel spring assembly, 4
...Robot, 5...Arm, 6...Hand, 1
1, 23...Strain gauge, 20...Cross spring.

Claims (1)

[Claims] 1. A second member via an elastic body supported by a first member.
A support device for supporting members, wherein the elastic body includes a pair of first parallel plate springs having one end connected to the first member, and a pair of first parallel leaf springs having one end connected to the second member. The second parallel leaf spring is connected to the other end of the first parallel leaf spring, and the other end of the second parallel leaf spring is connected to be perpendicular to the displacement direction of the first parallel leaf spring. a connecting member provided at a connecting portion between the first member or the second member and the elastic body, the connecting member is provided at a connecting portion between the first member or the second member and the elastic body, and
A support device comprising: a parallel leaf spring; and a cross-shaped leaf spring that is displaced in a direction perpendicular to a direction in which the second parallel leaf spring is displaced. 2. The support device according to claim 1, wherein the cross-shaped leaf spring is configured such that each leaf spring constituting the cross is rotatably supported around an axis parallel to its longitudinal direction. 3 A pair of first members comprising a first member and a second member supported by the first member via an elastic body, the elastic body having one end connected to the first member. a pair of second parallel leaf springs, one end of which is connected to the second member, the other end of the first parallel leaf spring is connected to the second parallel leaf spring; a connecting member whose other end is connected perpendicular to the displacement direction of the first parallel plate spring; and a connecting member provided at a connecting portion between the first member or the second member and the elastic body; the direction of inclination of the second member with respect to the first member, and the direction of inclination of the second member with respect to the first member
A support device comprising at least a parallel leaf spring and a cross-shaped leaf spring that is displaced in a direction perpendicular to a direction in which the second parallel leaf spring is displaced, wherein the first parallel leaf spring, the second parallel leaf spring A displacement detecting means for detecting displacement of each of the parallel leaf spring and the cross-shaped leaf spring, and a control means for controlling the position of the first member based on a detection signal of the displacement detecting means. A support device characterized by: 4. The support device according to claim 3, wherein the displacement detection means is a strain gauge attached to each of the leaf springs. 5. The cross-shaped leaf spring according to claim 3 or 4, wherein each of the leaf springs constituting the cross is rotatably supported around an axis parallel to the longitudinal direction of the leaf spring. Support device.