JPH06102314B2 - Articulated robot - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an articulated robot, and more particularly to a mechanism capable of reducing power required for operation by eliminating an influence of its own weight in bending operation of the arm.

[Prior art]

FIGS. 1 (A) and 1 (B) respectively show an example of a mechanism for canceling its own weight in a conventional articulated robot. That is, FIG. 1 (A) uses a tension coil spring, and FIG. 1 (B) uses a torsion coil spring, which are designed to eliminate the influence of their own weight by the spring force of these springs. .

Therefore, in FIG. 1 (A), the robot arm 1 is rotatably held by the rotary shaft 2, and the tension coil spring 4 is stretched between the arm 1 and the base body 3 to rotate the arm 1. As a result, the spring force of the spring 4 increases and the weight of the arm 1 is canceled.

Further, in FIG. 1 (B), the torsion coil spring 5 is attached to the rotating shaft 2
Is wound around and the both ends thereof are hooked on the arm 1 and the base body 3, thereby utilizing the spring force generated by the torsion of the spring 5.

However, when the tension coil spring 4 is applied to the articulated robot configured as described above, the spring force of the spring 4 temporarily increases the weight of the arm 1 until the arm 1 is rotated 90 degrees from the vertical position. Although it cancels, the action of the spring force of the spring 4 depends on the position at which the spring 4 is locked.
It is not possible to accurately cancel the self-weight of each arm, and for example, as shown in FIG. 2, the peaks of the torque curves T1 and T2 of the spring force and arm self-weight generated with the rotation angle of the arm 1 are deviated. ,
The efficiency of cancellation is totally reduced.

Further, when the torsion coil spring 5 is applied, assuming that the spring force of the spring 5 and its own weight are matched at a turning angle of 90 degrees as shown by a curve T3 in FIG. Not only does it decrease, but at a turning angle of 90 degrees or more, no canceling effect is obtained, and in any case, it does not contribute much to the reduction of the power required for the operation of the robot.

〔Purpose〕

The object of the present invention is to eliminate the above-mentioned drawbacks, to obtain the effect of canceling the influence of the self weight of the arm over a wide range of the rotation angle, and to secure an effective cancellation amount according to the rotation angle. To provide a multi-joint robot.

〔Example〕

FIG. 3 shows a basic basic structure applied to the present invention, in which 11 is an arm which is rotated by a shaft 12, and a tension coil spring is provided between an end 11A of the arm 11 and the base body 3. 14 are stretched. When the robot arm 11 configured as described above is rotated, the spring 14 extends, and a pullback torque of the arm 11 due to the spring force is generated according to the rotation angle θ °.

So now, the distance from the center of the rotating shaft 12 to the end 11A,
That is, the torque lever length is R and the spring 14 mounting length is P.
Letting S be the free length and k be the spring constant, the torque T can be expressed by the following equation.

Here, FIG. 4 shows a state in which the torque T changes in accordance with the turning angle θ °, and thus the maximum torque can be generated at a position exceeding the turning angle 90 ° by α °, for example.

The present invention applies such a structure. That is, since the torque due to the weight of the arm 11 forms a sine curve as shown by T2 in FIG. 2, it is possible to apply the structure shown in FIG. It is desirable that the difference between the load and the torque due to the weight of the arm be reduced even more in a portable manner.

Therefore, based on the basic structure shown in FIG. 3, the configuration is made as shown in FIG. Where 21 is an arm and 23 is an arm 21
Is a rotary plate which is formed integrally with the base end part of and is formed in a circular shape concentric with the rotary shaft 22. In this rotating plate 23 functioning as the torque lever of the present invention, circular arc grooves 24 and 25 symmetrical with respect to the center line 21A of the arm 21 are bored as engaging grooves of the present invention,
Roller pins 26 and 27, which are free-rolling connection engaging members of the present invention, are held in these grooves 24 and 25, and tension coil springs 28A and 28B are provided between the pins 26 and 27 and the base body 3. Hang up.

Note that α ° is pinned to the lower ends 24A and 25A of the grooves 24 and 25.
The angle formed by the radius including the pin axis and the center line 21A of the arm 21 when 26 and 27 are respectively positioned, and β ° is when the pins 26 and 27 are positioned at the lower ends 24B and 25B of the groove, respectively. It is the angle formed by the radius including the pin axis and the arm center line 21A.

Therefore, in setting the angles α and β here, the angle α is set to the angle α which is delayed from 90 degrees of the maximum torque generation shown in FIG. 4, and the angle β is set to the maximum of the robot arm 21. Adjust to the rotation angle up to the vicinity of torque generation.

Next, the gravity canceling operation in the articulated robot thus configured will be described.

Now, assuming that the arm 21 is rotated clockwise as shown by an arrow in FIG. 5, the spring force increases due to the extension of the spring 28A, and its torque is changed as shown by a curve T4 in FIG. Thus, the maximum torque position can be matched with the maximum torque position of the torque curve T2 due to the weight of the arm 21.

At the same time, the spring 28B contracts until the arm 21 rotates by α ° and the pin 27 reaches the original center line 21A, and the torque becomes zero at this position. Then, after that, since the pin 27 rolls along the circular arc groove 25, the spring 27 remains in the state of being aligned with the original center line 21A, and the torque is shown by the curve T5 in FIG. It remains zero as shown in.

Then, when the arm 21 is rotated by β °, the pin 27 is moved to the end 25B
The spring 28B is then stretched and thus the torque is also increased from zero as shown by curve T5.

Thus, when the arm 21 is rotated clockwise, the torque curve due to the resultant force of the two springs 28A and 28B becomes like T6, and it is possible to approach the torque curve T1 due to the weight of the arm 21. It is possible to enhance the gravity canceling effect over the entire rotation angle.

In the above description, the tension coil springs 14, 28A and 2
Although we have not described the detailed characteristics of 8B, the spring 14 and 28A and 28B are made of non-linear springs or air springs made of a shape memory alloy, or a combination of a plurality of springs. It goes without saying that it is possible to increase

Furthermore, in the example of FIG. 5, the shapes of the grooves 24 and 25 are changed to the rotary plate.
Although the arc shape is concentric with 23, the shape of the grooves 24 and 25 is not limited to this, and it is possible to perform more effective gravity cancellation by setting an appropriate curved shape. Of course.

〔effect〕

According to the articulated robot of the present invention, the base end portion of the working arm is rotatably supported with respect to the rotating shaft, and the torque arm is projected to the opposite side of the working arm with the rotating shaft interposed therebetween. A pair of arcuate engagement grooves are formed in the torque arm symmetrically with respect to an axis passing through the rotation axis, and a pair of coupling engagement members are slidably engaged with the pair of engagement grooves, Both ends of the pair of spring members are connected symmetrically with respect to the axis to the pair of coupling engagement members and the base body holding the rotating shaft, and a pullback torque opposite to the rotating direction of the working arm is generated. As a result, the influence of the weight of the arm can be properly erased according to the rotation angle of the arm, and when the operation is taught,
The arm is easy to move and requires less power, and further, it is possible to prevent the arm from descending due to its own weight when the power source is cut off.

[Brief description of drawings]

FIGS. 1 (A) and 1 (B) are model diagrams respectively showing an example of a mechanism for canceling the influence of the weight of the arm in a conventional articulated robot, and FIG. 2 is a torque obtained by a spring of the canceling mechanism. And a characteristic curve diagram showing the characteristics of the torque with respect to the turning angle due to the weight of the arm, FIG. 3 is a principle explanatory diagram of the basic structure applied to the present invention, and FIG. 4 is the structure of FIG. FIG. 5 is a characteristic curve diagram of the torque of the spring with respect to the turning angle, FIG. 5 is a model diagram showing an example of the configuration of the multi-joint robot of the present invention, and FIG. 6 is a torque due to the weight of the spring and arm of the multi-joint robot of the present invention. It is a characteristic curve figure with respect to the rotation angle of. 1 ... arm, 2,12,22 ... rotating shaft, 3 ... base, 4 ... tensile coil spring, 5 ... torsion coil spring, 11,21 ... arm, 11A ... end, 14, 28A, 28B …… tension coil spring, 21A …… center line, 23 …… turning plate, 24, 25 …… groove, 24A, 24B, 25A, 25B …… end, 26, 27 …… pin.

Claims (1)

[Claims] 1. A working arm having a base end pivotally supported about a rotation shaft, and a torque arm projecting to the opposite side of the work arm with the rotation shaft interposed therebetween. A pair of arcuate engagement grooves formed in the torque arm symmetrically with respect to an axis passing through the rotation axis, and a pair of coupling engagement members slidably engaged with the pair of engagement grooves, respectively. And a pair of spring members whose both ends are connected symmetrically with respect to the axis line to the pair of coupling engagement members and the base body that holds the rotating shaft, respectively. .