JPH0653353B2 - Robot arm with brake - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention uses an air bag type pneumatic actuator that expands and deforms by the supply of a pressurized fluid to generate a contracting force in the axial direction. The present invention relates to a robot arm with a brake.

(Prior Art) There are various types of actuators for robot arms. In comparison with other actuators, pneumatic actuators are more resistant to overload, generate less heat, and pose less danger to the human body, and thus their use has been greatly desired in recent years. However, many conventional pneumatic actuators are of the so-called air cylinder type, and the cylinder piston assembly is usually made of iron, and the weight of the operating section tends to be excessive relative to the operating force. there were.

On the other hand, an air bag type is also known. In this case, since the axial contracting force based on the bulging diameter by applying the control pressure of the air bag is used as the operating force, the air bag itself is lightweight and the sliding part is It is not included and the advantages such as the influence of frictional force and the fear of air leakage are recognized.

As such an air bag type pneumatic actuator, for example, one shown in FIG. 6 is conventionally known as described in Japanese Patent Publication No. 52-40378. This pneumatic actuator
In consideration of air impermeability and flexibility, the tubular body 1 made of, for example, rubber or a rubber-like elastic material is made to reach a so-called static angle (54 ° 44 ′) when the tubular body 1 is filled with the internal pressure to have the maximum expansion. The knitted braided structure 2 is covered, the closing members 3 are inserted into the openings at both ends, and the caulking cap 4 is used to seal and join the tubular body 1. A fitting 6 communicating with the inner cavity 5 of the tubular body 1 on at least one side is attached to one of the closing members 3.

The operation is performed by connecting an operating pressure source (not shown), for example, an air compressor, to the fitting 6 by a pipe line including a three-way valve, and applying a control pressure in the internal cavity 5 of the tubular body 1 to thereby form the braided structure 2 The expansion of the braid angle, that is, the expansion of the tubular body 1 and the contraction force in the axial direction resulting from the expansion, that is, the distance between the connecting pin holes of the closing member 3, are reduced by the panda graph motion.

On the other hand, by releasing the control pressure, the air in the internal cavity is diffused into the atmosphere through the three-way valve, and the tubular body 1 restores and expands as the braid angle θ of the braided structure 2 decreases. Nor.

Therefore, such a pneumatic actuator
For example, a wire is wound around a pulley rotatably attached to the end of the frame, both ends of the wire are connected to one end of the pneumatic actuator, and the other end of the pneumatic actuator is pinned to an appropriate fixing member. Obviously, the coupling can impart a rotational movement to the pulley.

(Problems to be Solved by the Invention) However, such a pneumatic actuator has a problem that the position controllability is particularly poor due to the occurrence of minute vibrations due to the elasticity of the actuator itself.

For example, even if the pulley or the member to which the pneumatic actuator is attached is to be held in the same position in the state where the desired rotational displacement is applied to the pulley by the pneumatic actuator, the pulley or the attachment may be The member may also vibrate slightly.

Further, if the pressurized fluid in the pneumatic actuator is discharged for some reason, the drive device will no longer be constrained, and there will be a problem that the device will move in a lateral direction.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the robot arm with a brake of the present invention, one end of each of a pair of arm driving means is attached to a swing frame member, and the other ends thereof are attached. Are connected to each other via a rotating member provided on the swing frame member, and at least one of the two arm driving means is provided with an elastic tubular body and a braided structure, and is contracted in the axial direction by supplying a pressurized fluid. A pneumatic actuator configured to generate a force is provided with a brake means for suppressing the rotational movement of the rotary member, and the brake means rotates the friction element that abuts the rotary member and the friction element. Spring means for urging in the direction of abutting the moving member,
The friction element is configured to be displaced by a method of separating from the rotating member, and an elastic contractor having the same configuration as the pneumatic actuator.

Further, another robot arm has a brake arm for controlling the rotational movement of the rotary member, in particular, a lever arm pivotally supporting an intermediate portion, and one end of each lever arm is connected to each end portion of the lever arm. Spring means having the other end fixed, and
The elastic actuator has a structure similar to that of the pneumatic actuator, and a friction element that is brought into contact with a brake drum provided integrally with the rotating member by the rotating movement of the lever arm. .

(Operation) Next, the operation of the robot arm with a brake having the above-described configuration will be described.

Now, a pressurized fluid, specifically compressed air, is supplied to the pneumatic actuator to generate a contracting force in the axial direction thereof, thereby imparting a rotating motion to the rotating member. When the rotary member has performed the desired rotary motion, the supply of compressed air to the pneumatic actuator is stopped, and the stretched state of the pneumatic actuator is maintained. At this time, if the braking means is actuated to suppress the movement of the rotating member, the rotating member will not vibrate slightly due to the minute vibration caused by the elasticity of the pneumatic actuator itself as in the conventional case. That is, by providing the braking means on the robot arm which is driven by the pneumatic actuator and has a relatively large compliance (here, "displacement / external force") with respect to the rotating member,
The compliance of the robot arm can be changed.

Further, when the robot arm is moved to the next operation position, the pressure inside the pneumatic actuator is reduced by supplying compressed air to the pneumatic actuator in advance with the braking means fully actuated. By eliminating the time delay for ascending and opening the braking means when the predetermined pressure is reached, the responsiveness is improved and the robot arm moves quickly.

Further, here, an elastic contraction body having the same structure as a pneumatic actuator for driving an arm is used for the operation of the braking means, and the braking means is opened when compressed air is supplied to the elastic contraction body. As a result, if the pneumatic actuator for driving and the elastic contractor cannot operate due to a power failure or other reasons,
The braking means can be activated automatically by the action of the spring means.

Moreover, in this robot arm, the compliance of the robot arm can be appropriately changed by selecting the supply internal pressure of the pneumatic actuator, and the braking force exerted on the rotating member by the braking means can be controlled by the elastic contractor. The adjustment can also change the compliance of the robot arm.

That is, when the braking means is fully activated,
Regardless of whether the internal pressure supplied to the pneumatic actuator is high or low, the rotating member is locked by the braking means, and the robot arm has high rigidity, while the braking force of the braking means on the rotating member is increased. By adjusting, the restraining force of the robot arm,
As a result, the compliance can be changed. For example, for a robot arm having high compliance, a braking force low enough to suppress microvibration of the pneumatic actuator can be used.
By braking the position of the robot arm, the position of the soft robot arm can be controlled with high accuracy without causing microvibration, which is why
It is possible to handle fragile eggs, cups, etc. Conversely, for robot arms with low compliance, the micro-vibration of the pneumatic actuator is suppressed and it acts on the robot arm relatively. By increasing the braking force to the extent that even small external forces can be counteracted, the robot arm is allowed to escape from impacts and other large external forces that act on the robot arm, and both the robot and work are sufficiently protected. In addition, it is possible to perform work requiring driving propulsive force such as screw tightening.

(Example) A robot arm with a brake according to the present invention will be described in detail below with reference to the drawings.

The same reference numerals as those in FIG. 6 denote the same components.

FIG. 1 is a diagram schematically showing the device of the present invention.

Here, a rotating member, for example, a pulley 11 is rotatably supported by the swing frame member 10, and a brake drum 13 is fixed to a shaft 12 that is integral with the pulley 11, so that the pulley 11 and the brake drum 13 are attached. If possible, it is possible to rotate with. A connecting member, for example, a wire 14 is wound around the pulley 11, and both ends of the wire 14 are connected to the eye of the closing member 3 by one ends of the two pneumatic actuators 8. The other end of each pneumatic actuator 8 is pin-connected to the fixing member 9 of the swing frame member 10 via the closing member 3. Therefore, fitting 6 to one pneumatic actuator
The compressed air is supplied via the pneumatic actuator and the compressed air is discharged from the other pneumatic actuator to rotate the pulley 11. Therefore, the shaft 12 rotates about its own axis, and the frame member 10 also rotates about the axis of the shaft 12. With this structure, a robot arm driven by supplying / discharging compressed air to / from an air bag type pneumatic actuator is obtained.

Further, here, a friction element, for example, a brake shoe 15 is arranged so as to face the outer peripheral surface of the brake drum 13. The brake shoe 15 is biased so as to be separated from the brake drum 13 when it is not operated, and is pressed by the brake cam 16 to contact the brake drum 13 when it is operated.

The brake cam 16 is eccentrically attached to a shaft that rotates together with the lever arm 17. The lever arm 17
An elastic contraction body 18 having the same structure as the pneumatic actuator 8 is attached to one end of, and a tension spring 19 is attached to the other end. Therefore, as shown in FIG. 1 (a), when compressed air is supplied to the elastic contraction body 18 through the fitting 6, the elastic contraction body 18 is expanded and deformed to generate a contraction force in the axial direction.
As a result, the lever arm 17 rotates about its own axis in the direction indicated by the arrow A in the figure against the contracting force of the tension spring 19, and the brake cam 16 is eccentrically attached to the axis of the lever arm 17. Is separated from the brake shoe 15.

The operation of the braking means thus configured will be described below. When the robot arm makes a desired motion to reach a predetermined position by supplying / discharging the pressurized fluid to / from each pneumatic actuator 8, those pneumatic actuators 8 are left as they are and compressed air is compressed from the elastic contracting body 18. Is discharged. As a result, the contraction force of the tension spring 19 overcomes the contraction force of the pneumatic actuator to rotate the lever arm 17 in the direction opposite to the arrow A. Therefore, the brake cam attached to the shaft of the lever arm 17
The brake shoe 1 rotates eccentrically around the axis of the arm 17.
5, the brake shoe 15 is pressed against the brake drum 13. As a result, the brake drum 13
As a result of suppressing the rotation of the pulley 12, the rotation of the pulley shaft 12 to which the drum 13 is fixed is also suppressed.
1 no longer makes rotational movements. This situation is shown in Figure 1.
Shown in (b). Therefore, the pneumatic actuator 8
Even if vibration occurs due to the elasticity inherent in the, the movement of the pulley is suppressed, so that the swing frame member 10 is also held in a fixed position.

By the way, in this case, by adjusting the discharge amount of the compressed air from the elastic contraction body 18, the brake shoes 15 are balanced under the balance between the contraction force of the elastic contraction body 18 and the tensile force of the tension spring 19. Of the pressing force on the brake drum 13,
As a result, the braking force can be controlled appropriately,
This makes it possible to select the compliance of the robot arm as required.

It should be noted that the advantage of arranging the braking means to take the operating position by discharging the compressed air from the elastic contraction body 18 is that when the elastic contraction body 18 is damaged, the pneumatic actuator 8 and the elastic actuator 8 are elastically broken due to a power failure or the like. When the pressure is discharged from the contracting body 18, the tension spring 19
Turns lever arm 17 in the opposite direction of arrow A,
Abut the brake shoe 15 on the brake drum 13,
Finally, deactivate the robot arm. However, the invention is not limited to this, and the brake shoe 15 may be configured to abut against the brake drum 13 by supplying a pressurized fluid to the elastic contraction body 18 that constitutes the braking means.

FIG. 2 shows an example of a case in which the robot arm with a brake schematically shown in FIG. 1 is housed in a casing. For simplification, the pneumatic actuator 8 for driving the robot arm, the frame member 10, the pulley 11, and the wire 14 are omitted.

In the embodiment shown in FIG. 2, a displacement gauge 21, for example, a rotary encoder is provided so as to engage with the shaft 12 of a pulley (not shown), and the displacement gauge 21 can detect the rotational displacement of the pulley. Is configured. Reference numeral 20 is a casing containing a robot arm with a brake. Its operation is no different from that shown in FIG.

FIG. 3 shows a braking means having another structure. Fig. 3
In (a), an inclined step portion 21 is formed on the shaft 12 of the pulley 11, and the brake shoe 15 is arranged on this step portion so as to be able to abut. The brake shoe 15 has a tension spring 19 at one end.
And the other end is engaged with the elastic contracting body 18 for driving the brake. In addition, the tension spring 19 and the elastic contraction body 18
Each one end is pin-connected to an immovable member such as the casing 20. Reference numeral 22 denotes a bearing that supports the shaft 12 of the pulley 11. Since the pressurized fluid is not supplied to the elastic contraction body 18 when the pulley is operated, the brake shoe 15 as a friction element is separated from the inclined step portion 21 by the tension spring 19 and allows the rotation of the pulley. On the other hand, when the arm is held at a desired position, a pressurized fluid is supplied to the elastic contraction body 18 to generate a contraction force. If the contracting force is larger than the contracting force of the tension spring 19, the brake shoe 15 is displaced downward in FIG. 3 (a) against the spring force, abuts against the inclined step portion 21, and inhibits the rotation of the shaft 12. . Therefore, here, the brake shoe 15 indirectly contacts the pulley 11 via the shaft 12, and the pulley 11 is held at a predetermined position. If the elastic contraction body 18 and the tension spring 19 are arranged so as to be replaced with each other, the braking means can be set to the non-actuated position when the pressurized fluid is supplied, as in the embodiment shown in FIG. it can.

The embodiment shown in FIG. 3 (b) uses a first lever arm 17a and a second lever arm 17b whose one ends are rotatably interconnected to each other, and is attached to the first lever arm 17a as a friction element. Brake shoe 15 to pulley 11
It prevents the pulley from rotating by colliding with. Therefore, the other end of the first lever arm is pin-connected to a stationary member such as the casing 20, and the other end of the second lever arm 17b is connected to the elastic contracting body 18 for driving the lever arm.
The other end of the elastic contraction body 18 is pin-connected to a stationary member such as the casing 20. Further, a tension spring 19 is provided in order to apply a force opposed to the operation of the elastic contraction body 18 to the lever arm.

When the pulley 11 is in operation, no pressurized fluid is supplied to the elastic contractor 18, so that the tension spring 19 causes the elastic contractor 18 to move.
In (b), the first lever arm 17a is rotated counterclockwise and positioned. Therefore, the brake shoe 15 fixed to the first lever arm 17a is separated from the pulley 11 and allows the pulley to rotate. On the other hand, when a pressurized fluid is supplied to the elastic contractor 18, the second lever arm 17b rotates about the fulcrum 23 against the tension spring 19, and the first lever arm 17a moves to the position shown in FIG. Push upwards at. Therefore, the brake shoe 15 attached to the first lever arm 17a abuts on the pulley 11 to prevent the pulley from rotating and maintain the pulley 11 at a predetermined position.

In addition to the above, as the braking means, it is also possible to use electricity or hydraulic pressure, but considering the problems of explosion proof, weight, piping, cost, and leakage of hydraulic oil, as in the above-mentioned embodiment, It is advantageous to use braking means driven by an elastic contractor having a similar construction to the pneumatic actuator 8.

The embodiment shown in FIG. 4 is a robot arm for fastening bolts which is connected to two L-shaped robot arms 29 and 30 with a brake similar to that shown in FIG. The motor 25 is fixed to the fixed member side of the arm 30 via the bracket 24. This motor 2
A box-shaped wrench is attached to the output shaft of 5, and the head of the bolt 27 is fitted therein. 28 is a wrench 2
6 is a feeding device for feeding 6 forward and is operated by rotation of the motor 25.

The arms 29 and 30 are appropriately rotated to position the bolt 27 at a desired position. Next, the motor 25 is operated and the bolt 27
To conclude.

FIG. 5 shows another embodiment of the present invention in which one of the pair of arm driving means is a spring 31. The spring 31 is similar to the embodiment shown in FIG. 1 except that one end of the spring 31 is fixed to a stationary member such as the casing 20 of the arm.

(Effects of the Invention) As described in detail above, the device of the present invention has a peculiar problem caused by the elasticity of an air bag type pneumatic actuator, that is, a peculiar problem that compliance is large and microvibration easily occurs. The problem was solved by providing the brake means, and the applicable range of the robot arm using the pneumatic actuator as a driving device was expanded.

More specifically, when a relatively large compliance is required, the braking means is utilized by taking advantage of the characteristic of the pneumatic actuator capable of appropriately changing the compliance by adjusting the pressure of the pressurized fluid. Allows the robot arm to have a sufficiently soft spring characteristic by applying the minimum necessary braking force, while on the other hand, for tasks requiring low compliance such as screw tightening, the pneumatic actuator is By increasing the supply internal pressure and increasing the braking force of the braking means to the extent that a relatively small external force can be suppressed, it is possible to sufficiently generate the drive propulsion force necessary for screw tightening work, etc. With respect to the action of a large external force, let it escape It is possible to sufficiently protect the respective body and the workpiece.

Also, for the operation of the braking means, an elastic contractor having the same structure as the pneumatic actuator is used,
When the pressurized fluid is supplied, the braking means is in the inactive position, so when the equipment that supplies the pressurized fluid to each pneumatic actuator and elastic contractor does not operate due to a power outage, etc. When the elastic contractor is damaged, the braking means can be immediately actuated to prevent an unexpected movement of the robot arm.

Before further moving the robot arm to the next operating position, the brake means is brought into its fully operating state to lock the robot arm, and compressed air is supplied to the pneumatic actuator for driving the arm. By releasing the brake after increasing the pressure, the robot arm can be moved quickly without the time delay due to the pressure increase.

[Brief description of drawings]

1 (a) and 1 (b) are views schematically showing the device of the present invention, and FIG.
The figure shows a part of an arm incorporating the device shown in FIG. 1, and FIGS. 3 (a) and 3 (b) show other braking means applicable to the device shown in FIG. FIG. 4 is a perspective view showing the external appearance of a bolt fastening robot incorporating the device shown in FIG. 1, FIG. 5 is a view schematically showing another embodiment of the present invention, and FIG. FIG. 3 is a partial partial cross-sectional view showing a known pneumatic actuator. 1 ... Tubular body 2 ... Braided structure 3 ... Closing member 4 ... Caulking cap 5 ... Internal cavity 6 ... Fitting 8 ... Pneumatic actuator 9 ... Fixing member 10 ... Oscillating frame member 11 …… Pulley 12 …… (Pulley) axis 13 …… Brake drum 14 …… Wire 15 …… Brake shoe 16 …… Brake cam 17 …… Lever arm 18 …… Elastic contraction body 19 …… Tension spring 20 …… Casing 21 ... Inclined step 22 ... Bearing 23 ... Support 24 ... Bracket 25 ... Motor 26 ... Wrench 27 ... Bolt 28 ... Feeding device 29, 30 ... Arm 31 ... Spring

Claims (2)

[Claims] 1. A pair of two arm driving means are attached at one end thereof to a swing frame member, and the other ends thereof are interconnected via a turning member provided at the swing frame member, and at the same time, When at least one of the arm driving means is constituted by a pneumatic actuator having an elastic tubular body and a braided structure and generating a contracting force in the axial direction by supplying a pressurized fluid, the rotational movement of the rotating member And a spring element for urging the friction element in contact with the rotating member in a direction to bring the friction element into contact with the rotating member; Against the spring force of the means, to displace from the rotating member,
A robot arm with a brake, which is composed of an elastic contractor having the same structure as the pneumatic actuator. 2. A pair of two arm driving means are attached at one end to a rocking frame member, and the other ends thereof are interconnected via a turning member provided on the rocking frame member. When at least one of the arm driving means is constituted by a pneumatic actuator having an elastic tubular body and a braided structure and generating a contracting force in the axial direction by supplying a pressurized fluid, the rotational movement of the rotating member And a spring means having one end connected to each end of the lever arm and the other end fixed, and a lever arm having a middle portion pivotally supported. Of an elastic contractor having the same structure as a matic actuator, and a brake drive integrally provided on the rotating member by the rotating movement of the lever arm. Robot arm with brake consisting of a friction element that comes into contact with the arm.