JPH0346275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an industrial robot equipped with a pneumatic actuator that applies an upward balancing moment to a robot arm.

(Prior Art) By urging the robot arm upward with the pneumatic actuator as described above,
The applicant has already proposed a balance device configured to apply a balance moment that opposes the gravitational moment to the robot arm, but this conventional balance device The air pressure supplied to the actuator can be changed in two stages, and two types of balance moment, large and small, can be used properly in response to the gravitational moment that continuously changes due to the swinging of the robot arm. Ta.

(Problem to be Solved by the Invention) However, simply switching the balance moment between two stages in this way does not always maintain the robot arm in a perfect equilibrium state. Therefore, for example, according to what is described in Japanese Patent Publication No. 58-47315 and Utility Model Publication No. 57-39192, etc., the balance moment is approximately parallel to the gravitational moment that changes in response to the swinging of the robot arm. Automatic pressure adjustment means is provided for continuously changing the pneumatic pressure supplied to a pneumatically actuated actuator that applies an upward balance moment to the robot arm in conjunction with the swinging of the robot arm so that the robot arm has an upward balance moment. However, no consideration has been given to how to specifically implement the automatic pressure adjustment means.

That is, the automatic pressure adjustment means continuously detects the swing angle of the robot arm, and uses a microcomputer or the like to calculate the optimal pressure to be supplied to the actuator from the detected robot arm angle. Generally, a method is considered in which the set pressure of the pressure regulating valve is automatically adjusted based on the result of this calculation, but such a method inevitably increases the cost significantly, making it difficult to use pneumatically operated robots, which are characterized by low cost. This results in the loss of benefits.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention provides a pneumatically actuated actuator that applies an upward balance moment to the robot arm as described above. The air pressure supplied to the yuator is continuously adjusted in conjunction with the swinging of the robot arm so that the balance moment is approximately balanced with the gravitational moment that changes in response to the swinging of the robot arm. In a robot equipped with an automatic pressure adjustment means that changes the pressure to
The automatic pressure adjustment means is comprised of a pressure adjustment valve, a cam attached to the swinging center of one of the robot arms and a member that pivotally supports the robot arm, and a cam attached to the other of the robot arms and a member that pivotally supports the robot arm. The present invention proposes a robot equipped with a pneumatically operated balance device comprising a pressure regulating spring of a pressure regulating valve and a cam follower for regulating the pressing force.

(Embodiment) Next, a preferred embodiment of the present invention will be described. First, an outline of a pneumatically operated robot will be explained based on FIGS. 1 to 3.

In FIGS. 1 and 2, 1 is a base, 2 is a rotary table rotatably supported on the base 1 so as to be rotatable around a vertical axis 3, and 4 is the rotary table 2 and an intermediate member. 5 is a longitudinal swinging arm that connects the intermediate member 5 and the tip member 7, and 6 is a vertical swinging arm that connects the intermediate member 5 and the tip member 7.

The longitudinal swinging arm 4 is made up of a pair of front and rear parallel swinging links 8a and 8b, and is used to move the intermediate member 5 in the longitudinal direction relative to the rotary table 2 while maintaining a constant posture. The vertically swinging arm 6 is made up of a pair of upper and lower directional swinging links 9a and 9b, and is configured to move the tip member 7 in the vertical direction relative to the intermediate member 5 while keeping its posture constant. Although not shown, the robot hand is attached to the tip member 7 via a suitable actuator. Reference numeral 10 denotes a pneumatic actuator that rotates the rotary table 2 within a predetermined range with respect to the base 1, and is attached to the base 1. Reference numeral 11 denotes a pneumatically actuated actuator for driving a front and rear swinging arm attached to the rotary table 2, which swings the link 8a within a predetermined range via a drive shaft 12 on the rotary table 2 side. Reference numeral 13 denotes a pneumatic actuator for driving a vertically swinging arm attached to the intermediate member 5, which swings the link 9b within a predetermined range via a drive shaft 14 on the intermediate member 5 side. Further, 15 is a pneumatically actuated actuator for a balancer that acts on the vertically swinging arm 6, and is connected to an intermediate member on the side opposite to the side where the pneumatically actuated actuator 13 for driving the vertically swinging arm is located. It is attached to 5,
The link 9b of the vertically swinging arm 6 is connected to the drive shaft 14.
is biased upward through the 16 is a pulse encoder that is linked to the rotation of the rotary table 2. A pulse encoder 17 is linked to the swinging of the longitudinal swinging arm 4, and is linked to the link drive shaft 12. A pulse encoder 18 is linked to the swinging of the vertical swinging arm 6, and is linked to the link drive shaft 14.

According to the above-mentioned pneumatically operated robot, the actuators 10, 11, and 13 are pneumatically operated to rotate the rotary table 2 with respect to the base 1 and to swing the longitudinal swing arm 4 with respect to the rotary table 2 in the front and rear directions. , and intermediate member 5
By causing the tip member 7 to perform a predetermined movement consisting of a combination of vertical swinging of the vertically swinging arm 6 relative to the robot hand, the workpiece to be held by the tip member 7 via an appropriate robot hand can be set in advance. It is possible to move the robot along the specified motion trajectory and automatically perform the desired work. On the other hand, the balancer pneumatic actuator 15 is supplied with pressurized air whose pressure is adjusted to correspond to the gravitational moment acting on the vertically swinging arm 6, so that the balancer's pneumatic actuator 15 is supplied with pressure air whose pressure is adjusted to correspond to the gravitational moment acting on the vertically swinging arm 6. Grant.

Next, based on FIG.
The control system of Nos. 3 and 15 will be explained. In the figure, 1
9, 20 are electromagnetic switching valves, 21, 22 are pressure regulating valves, 23 are reverse valves, 24, 25 are variable throttle valves,
26 to 28 are silencers. According to this pneumatic control system, the pneumatic pressure regulated by the pressure regulating valve 21 is supplied to the balancer pneumatic actuator 15 at a pressure regulated by the pressure regulating valve 22. An upward balance moment is applied to the swing arm 6. At this time, the pressure regulating valve 2
2, the pressure is continuously and automatically adjusted in conjunction with the swinging of the vertical swinging arm 6, as will be described later.

On the other hand, by turning on only the upper moving side electromagnetic switching valve 20 of the electromagnetic switching valves 19 and 20 (state in which air pressure is supplied to the actuator 13), the pressure is adjusted to a constant pressure by the pressure regulating valve 21. The air pressure is supplied to the normal rotation drive side port of the actuator 13 via the electromagnetic switching valve 20, the actuator 13 rotates in the normal rotation direction, and the vertical swing arm 6 moves upward. become. Exhaust gas from the actuator 13 is discharged from a muffler 26 via an electromagnetic switching valve 19 and a throttle valve 24. When only the lower solenoid switching valve 19 is turned on instead of the electromagnetic switching valve 20, the pressure regulating valve 21
Air pressure adjusted to a constant pressure is supplied to the reverse drive side port of the actuator 13 via the electromagnetic switching valve 19, and the actuator 13 rotates in the reverse direction and the vertical swing arm 6 When the actuator 13 moves downward, the exhaust gas from the actuator 13 is discharged from the silencer 27 via the electromagnetic switching valve 20 and the throttle valve 25.

When the vertical swinging arm 6 that moves upward or downward reaches the target stop position as described above, both the electromagnetic switching valves 19 and 20 are turned on and the same pressure of air is applied to both ports of the actuator 13. When the vertically swinging arm 6 is positioned at the target stop position, a brake means (not shown) that locks the vertically swinging arm 6 against the intermediate member 5 so that it cannot swing is actuated. The swing arm 6 is fixed at the set position.

Other actuators, namely, the pneumatically actuated actuator 10 for driving the rotary table and the pneumatically actuated actuator 11 for driving the front and rear swinging arms, are also pneumatically operated by the same control system as the actuator 13. After being driven and reaching the target position, the rotary table 2 and the back-and-forth swing arm 4 are fixed by the brake means as described above.

Next, the main parts of the embodiment of the present invention will be explained based on FIGS. 4 to 6.

As shown in FIG. 4, the upward balance moment M _B required to bring the vertically swinging arm 6 into a completely balanced state is proportional to the sine of the relative displacement angle θ of the arm 6 with respect to the horizontal plane. Of course, the balance moment M _B is the vertical load W acting on the vertically swinging arm 6 (the weight of the workpiece and the weight of the arm, etc.)
Fig. 4B shows the change in the balance moment _M when the maximum weight of the workpiece is set as a solid line, and the balance moment M when the workpiece weight is zero (only the weight of the arm, etc.). The change in _B is shown by the dashed line.

FIGS. 5 and 6 show specific means for obtaining the balance moment M _B as described above, and show a third means for adjusting the pressure of the air pressure supplied to the balancer pneumatic actuator 15. The pressure regulating valve 22 shown in the figure is attached to a pair of cams 29 and 30 on the link drive shaft 14 of the vertically swinging arm 6.
It is designed to be automatically controlled by

That is, the main pressure regulating valve 32 acts on the main air pressure supply path 31 that supplies air pressure to the actuator 15.
is pressurized by a compression spring 34 whose pressurizing force is adjusted by a first cam follower 33 that can move forward and backward, and air pressure supplied from a sub-air pressure supply path 35, and the sub-air pressure supply path 35 Sub-pressure regulating valve 3 that acts on
6 is pressurized by a compression spring 38 whose pressing force is adjusted by a movable second cam follower 37 and by auxiliary air pressure at a constant pressure supplied from an auxiliary air pressure supply path 39. The first cam follower 33 is configured to respond to the cam 29, and the second cam follower 37 is configured to respond to the cam 30.

The air pressure supplied to the auxiliary air pressure supply path 35 is manually adjusted by a pressure adjustment means (not shown) in accordance with the weight of the work being handled, and the main air pressure supply path 31 has a constant pressure. air pressure is supplied. Furthermore, when the vertical swing arm 6 is in a horizontal state, that is, when the necessary balance moment M _B is at its maximum, the cams 29 and 30 are moved by the springs 34 and 3 via the cam followers 33 and 37, as shown in FIG.
The cam 29,
30 is attached to the link drive shaft 14.

According to the above configuration, when the vertically swinging arm 6 is in a horizontal state, the pressing force of the springs 34 and 38 on the main pressure regulating valve 32 and the sub-pressure regulating valve 36 becomes maximum, and the main pressure regulating valve is supplied from the sub-air pressure supply path 35. The pressurizing air pressure is maximized. Therefore, the sum of the pressing forces acting on the main pressure regulating valve 32 is maximum, that is, the main pneumatic supply path 3
The set pressure of the main pressure regulating valve 32 for 1 becomes maximum, and the maximum pressure is supplied to the pneumatic actuator 15 for the balancer, and the vertical swing arm 6
The upward balancing moment M _B given to is the maximum.

When the vertical swinging arm 6 is caused to swing up and down, the cams 29 and 30 rotate accordingly.
The amount by which these cams press the springs 34, 38 via the cam followers 33, 37 is reduced.
Therefore, the pressing force on the main pressure regulating valve 32 and the sub pressure regulating valve 36 decreases, and the set pressure of the main pressure regulating valve 32 with respect to the main air pressure supply path 31 decreases, so that the air pressure supplied to the balancer pneumatic actuator 15 decreases. pressure decreases, and the upward balance moment M _B applied to the vertically swinging arm 6 decreases.

On the other hand, as a result of adjusting the air pressure supplied to the sub-air pressure supply path 35 in proportion to the weight of the work being handled, as the weight of the work increases, the pressing force against the main pressure regulating valve 32 increases, and the setting of this main pressure regulating valve 32 increases. Pressure increases. Therefore, the pressure of the air pressure supplied to the balancer pneumatic actuator 15 increases, and the upward balance moment M _B applied to the vertical swing arm 6 increases.

The upward balance moment M _B imparted to the vertically swinging arm 6 as described above is shown in Fig. 4B.
As shown in , the relative displacement angle θ of the vertically swinging arm 6 with respect to the horizontal plane changes in a sine curve shape in proportion to the sine, and the vertically swinging arm 6 has a size that is perfectly balanced against the gravitational moment no matter what angle it is at. The cams 29 and 30 are formed so that the air pressure to be supplied to the main pneumatic pressure supply path 31 and the auxiliary pneumatic pressure supply path 39 is set so that the pneumatic pressure to be supplied to the auxiliary pneumatic pressure supply path 35 is set according to the weight of the workpiece. Adjust accordingly.

That is, the air pressure supplied from the main air pressure supply path 31 to the balancer pneumatic actuator 15,
The air pressure is divided into a constant air pressure corresponding to the weight of the arm, etc., and a variable air pressure that corresponds to the weight of the workpiece, which changes in the range of 0 to maximum. In order to adjust it in proportion to the sine of the angle θ, the pressing force of the spring 34 against the main pressure regulating valve 32 is adjusted by the cam 29 and the cam follower 33, and the latter variable air pressure is adjusted to the relative displacement angle of the vertical swing arm 6 with respect to the horizontal plane. In order to adjust it in proportion to the sine of θ, the auxiliary air pressure supply path 35
The main pressure regulating valve pressurizing air pressure supplied from the cam 30
The set pressure is adjusted by a sub-pressure regulating valve 36 whose set pressure is adjusted by a cam follower 37.

As described above, the air pressure supplied to the pneumatic actuator that applies an upward balance moment to the robot arm is approximately balanced with the gravitational moment that changes in response to the swing of the robot arm. By providing automatic pressure adjustment means that continuously changes the pressure in conjunction with the swinging of the robot arm so that the robot arm always maintains equilibrium with the gravitational moment regardless of its swing angle. At the very least, it is possible to perform the desired motion with a small driving force, thereby greatly improving motion control. According to the configuration of the present invention, the following unique effects are expected. I can do it.

(Operations and Effects of the Invention) That is, according to the configuration of the present invention, the automatic pressure adjustment means is connected to one of the pressure adjustment valve, the robot arm, and a member that pivotally supports the robot arm. The cam is constructed of a cam attached to the swinging center of the valve, and a cam follower attached to the other side for adjusting the pressing force of the pressure regulating spring in the pressure regulating valve. As long as the shape of the robot arm is designed, it can be continuously adjusted according to the angle of the robot arm, in the same way as when a robot arm angle detection means and a microcomputer are mounted on the robot and the pressure regulating valve is automatically controlled electrically. The air pressure supplied to the actuator can be automatically adjusted as expected, and compared to the case where the pressure regulating valve is automatically controlled electrically as described above, the number of parts is extremely small and the structure is simple. It is very simple, can be implemented very cheaply, and is easy to maintain.

[Brief explanation of drawings]

Figure 1 is a side view, Figure 2 is a rear view with the lower part of the base omitted, Figure 3 is an explanatory diagram showing the pneumatic control system of the vertically swinging arm, and Figure 4 is an illustration of the vertically swinging arm. Figure 5 explaining the accompanying change in balance moment.
The figure is a vertical side view of the automatic pressure adjustment means, and FIG. 6 is a dynamic vertical front view. 1...Base, 2...Rotating table, 4...Back and forth swinging arm, 5...Intermediate member, 6...Vertical swinging arm,
7... Tip member, 10, 11, 13... Pneumatically actuated actuator, link drive shaft for vertically swinging arm, 15... Pneumatically actuated actuator for balancer, 19, 20... Electromagnetic switching valve, 21,2
2...Pressure regulating valve, 29, 30...Cam, 31...
...Main air pressure supply path, 32...Main pressure regulating valve, 33, 37
...Cam follower, 34, 38...Compression spring, 35...Sub-air pressure supply path, 36...Sub-pressure regulating valve, 39...Auxiliary air-pressure supply valve.

Claims (1)

[Claims] 1. A pneumatic actuator that applies an upward balance moment to the robot arm is provided, and the air pressure supplied to the actuator is controlled so that the balance moment is a gravitational moment that changes in response to the swinging of the robot arm. In a robot provided with an automatic pressure adjustment means that continuously changes pressure in conjunction with the swinging of the robot arm so that the pressure is approximately balanced in size, the automatic pressure adjustment means includes a pressure adjustment valve, a pressure adjustment valve, and a pressure adjustment valve. Among the robot arm and the member that pivotally supports the robot arm, a cam attached to the swinging center of one of the robot arms and a pressing force adjustment of a pressure regulating spring attached to the other pressure regulating valve. A robot with a pneumatically actuated balance device consisting of a cam follower.