JPS639954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a robot hand using a motor as a drive source, and more particularly to a robot hand capable of monitoring falling workpieces during the workpiece handling process.

[Background of the invention]

A robot hand is known in which a pulse motor or a servo motor is used as the drive source of the robot hand, and the gripping stroke can be selected from the outside. In addition, a sensor detects the reaction force applied to the chuck,
A device that detects whether or not the chuck is holding an object is also disclosed in JP-A-58-132484. However, in the conventionally proposed sensor using this type of sensor, the sensor is either emitting a signal because the chuck is holding the object it is trying to hold, or it is emitting a signal because the chuck is constantly touching an obstacle. I couldn't tell the difference.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a robot hand with a grip sensor that can determine whether the chuck is holding an object or simply touching an obstacle.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized by: a motor whose rotation angle can be controlled; a feed screw driven by the motor; a moving piece that moves on the feed screw; a chuck supported via a spring that is on the moving piece and has a preload; a movement sensor attached to a part of the chuck; a moving dock attached to a part of the moving piece; drive end signal inventing means for outputting a drive end signal at a position where the motor is rotated to a position where the planned object can be completely grasped; It is provided with a logic circuit that performs a logical operation on the signal that is output when the device is operated.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Figures 1a and b are examples of a hand in which the rotation axis of the pulse motor and the guide rod of the chuck are arranged in parallel, and Figures 2a, b, and c are examples of a hand in which the rotation axis of the pulse motor and the guide rod are arranged orthogonally. This is an example of a set hand.

In FIG. 1, the housing of the hand, 2 is a motor fixedly installed in the housing 1, for example, a pulse motor, and 3 is attached to the shaft 4 of the pulse motor 2, and is tensioned by a geared drive side pulley. The driven pulley 6 is rotated via the timing belt 5. A feed screw 7 rotates together with the driven pulley 6, and has a reverse screw thread that sandwiches the driven pulley 6. 8A, 8
B is a pair of moving pieces screwed into the reverse screws in the shape of a nut and moves along the guide rod 9, and when the moving pieces 8A and 8B are moved by the feed screw 7, the moving pieces 8A and 8B are rotated. I'm trying not to. 10A and 10B are springs, and 11 is a chuck for gripping objects, which is attached between the snap springs 12A and 12B of the movable pieces 8A and 8B against the springs 10A and 10B, and the other end is slidably fitted into the guide rod 9. There is. Also, 13
is a movable dog fixed to the movable pieces 8A, 8B, and is operated by a movable sensor (photoelectric switch) 14, which will be described later, moving against the springs 10A, 10B. 14 is a movement sensor attached to a part of the chuck 11B, 15a is a fixed sensor attached to the housing 1, which generates an output signal such as when the hand is open, and 15b is a fixed sensor attached to the housing 1, which generates an output signal when the hand is closed. Generates an output signal such as at the end. FIG. 4 is a diagram showing the characteristics of the hand, and the first quadrant is that when the chuck 11 grasps the workpiece, the movable pieces 8A and 8B move against the springs 10A and 10B to the center of the feed screw 7. The second quadrant is a diagram showing the relationship between the amount of spring push and the gripping force of the hand (spring reaction force) when
When the closed end of the chuck 11 is CL and the open end is OL, the point where the chuck 11 contacts the workpiece is the workpiece touch point OT, and when the most closed end CL is on the side of the driven pulley 6, the open end OL is the moving piece 8A. ,8B
The characteristic diagram in FIG. 4 shows the movement of one chuck 11 when the chuck 11 is moved to the outermost position.

Now, when the hand is open, the normal position of the chuck 11 is always between the open end OL and the workpiece touch point OT. To grasp the workpiece W, the chuck 11 first moves from the open end OL side toward the inside, that is, toward the workpiece touch point OT side. Check 1
The moving mechanism of No. 1 consists of screwing moving pieces 8A and 8B into a feed screw 7 with left and right reverse threads.
This is done by rotating the driven pulley 3 of the pulse motor 2 via the timing belt 5 with the driven pulley 6 fixed at the center of the motor. Thus, the chuck 11 comes into contact with the side surface of the workpiece at the workpiece touch point OT. Then, when the chuck 11 is further closed, the spring 10 is applied to the chuck 11.
The pressing force of A and 10B is added as a reaction, and the spring pushing amount PL becomes, for example, 1 as shown in Fig. 4.
If [mm] is used, it is the gripping force for the workpiece W.
GL is about 6 [Kg] or more, motor torque is about 3.5 [Kg-]
cm]. That is, the chuck 11 is the workpiece W.
If further gripping force is applied while in contact with the
The position of 1 is fixed depending on the dimensions of the workpiece W, but the movable pieces 8A and 8B move when the feed screw 7 is in a rotating state, so the springs 10A and 10B are compressed, and the spring pushing amount PL is selected. Therefore, the gripping force can be selected. Also, check 11
The support in the moving direction is provided by a two-point support mechanism as shown in FIG. One point is the one that slides on the movable pieces 8A, 8B against the springs 10A, 10B, and the back of the chuck 11 is the snap spring 12.
At the time when the chuck 11 is prevented from coming off by A and 12B, the spring reaction force GL has already been applied to the chuck 11.
However, as shown in FIG. 4, for example, the weight is slightly less than 5 kg. Second, the other end of the chuck 11 is slidably inserted into the guide rod 9, which helps the chuck 11 to move in parallel and improves its mechanical strength. The movement sensor 14 is fixedly attached to the chuck sliding portion on the guide roller 9, and the movement dog 13 for operating the movement sensor 14 is connected to the movement pieces 8A, 8B.
Since it is fixedly attached to one end, when the chuck 11 grips the workpiece W and the movable pieces 8A and 8B continue to move, the movement sensor 1
4 and the movable dog 13 gradually approach each other, and at a certain point, the movable dog 13 activates the movement sensor 14 and generates a gripping confirmation signal indicating that it is gripping the workpiece W with a predetermined gripping force, that is, tightening the workpiece more. Output a signal. This tightening signal is generated when the spring pushing amount PL reaches a certain value. Since the gripping force naturally needs to be selected depending on the weight and material of the workpiece, this is done by comparing the number of pulses generated by the pulse motor to the most ideal gripping force suitable for the weight and material of the workpiece.

In the case of the robot hand of this embodiment, one of the workpiece grip completion signals is a grip confirmation signal from the movement sensor 14, and the other is a drive end signal generated by a drive end signal generating means built in the pulse transmitter 21. It is acceptable to have an AND condition for two signals. The AND condition is calculated using the built-in logic circuit in the PC20. Therefore, if a gripping confirmation signal is issued during workpiece handling but a drive end signal is not issued, the AND condition will not hold, and the chuck 11 will determine that it is not holding a workpiece yet, and the chuck will not be able to handle anything other than the workpiece. It is determined that the robot has come into contact with an object, and a stop signal is automatically transmitted to the robot.

Also, the characteristics of the first quadrant in Fig. 4 are the spring 1
It differs depending on the design conditions of 0A and 10B,
Similarly, the motor torque in the characteristics of the second quadrant naturally changes depending on the motor characteristics.

FIG. 2 shows another embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals. In particular, Figures 1 and 2 are
Although there is no difference in terms of the characteristics shown in the figure, there is a difference in the motor torque transmission mechanism. That is, in Fig. 1, the motor shaft and the feed screw 7 of the chuck 11 are arranged in parallel, and the rotational torque is transmitted between them by a timing belt, whereas in Fig. 2, the feed screw 7 of the chuck 11 is directly connected to the motor shaft. Feed screw 71
The two guide rods 9 guide the chuck 11.
1 and 92, the movable piece 81 screwed into the feed screw 71 is moved up and down by the rotation of the motor. The workpiece retightening mechanism is shown in Figures 2b and 2c. 16 is a moving rod attached to the moving piece 81 by a pin 17, 18 is a fixed rod attached to the side surface of the sliding part of the guide rods 91, 92 of the chuck 11 by a pin 19, and the spring 10A (or 10B) is It is mounted under pressure between the movable rod 16 and the fixed rod 18. When the chuck 11 grips the workpiece, the feed screw 7
1 and move the moving piece 81 upward in the case shown. When the chuck 11 comes into contact with the workpiece,
Further movement of the chuck 11 is no longer possible. However, since the motor 2 continues to be driven, the moving piece 81 moves. The amount of movement of the moving piece 81 is determined by the amount of movement of the moving piece 81.
8 and the moving rod 16. Thus, when the drive of the motor 2 is stopped, the gripping force of the chuck 11 on the workpiece is provided by the compression force of the spring. Of course, although not shown, the amount of movement of the movable rod 16 is detected by a sensor as a retightening signal.

Further, FIG. 3 shows an example of a control system for the present robot hand. First, when a workpiece W is given, the gripping force is naturally determined depending on the size, material, and weight of the gripping section, so a BCD output signal is transmitted from the program controller 20 to the pulse generator. The pulse transmitter that receives the BCD signal converts the signal into a serial number of pulses, and the driver 2
The pulse motor 2 is driven by the drive signal from the driver 22. When the motor is driven and the chuck 11 grips the workpiece W, and a predetermined gripping force is applied, a sense up signal from the movement sensor 14 is fed back to the program controller 20, and at the same time, a drive end signal is sent from the pulse generator 21 to the program controller 20. The same is given. In this way, the program controller 20 considers that the gripping is completed based on the AND condition of the sense up signal and the pulse end signal, and moves on to the next step operation. The hand opening completion signal is sent with only the pulse end signal, and the program controller moves to the next step operation.

〔Effect of the invention〕

As described above, according to the present invention, a chuck is opened and closed using a motor whose rotation amount can be controlled from the outside as a drive source, and even when the chuck touches a workpiece, the spring is still activated by driving the motor. The compression force of the spring applies the gripping force of the hand, and at the time when the compression force is generated in the spring, the sensor is activated to signal tightening. Therefore, the opening/closing amount of the chuck can be adjusted according to the dimensions of the workpiece and the workpiece. Since it can be selectively opened and closed arbitrarily and at high speed to match the surrounding conditions of the tower mounting section, high-density mounting of assembled parts is possible. Additionally, during workpiece handling, a sensor signal that detects spring compression is continuously output, so if the workpiece is dropped midway through, the sensor signal is cut off and the robot operation is stopped. It can also be used as a fail-safe operation. Furthermore, since the spring push amount can be varied by the pulse number selection function of the pulse motor, the weight of the workpiece,
It has excellent effects such as being able to reliably grip the workpiece with any gripping force depending on the material.

[Brief explanation of the drawing]

Fig. 1 is a mechanical diagram showing an embodiment of the present invention, Fig. 1a is a cutaway front view, and Fig. 1b is a
FIG. 2 is a mechanical diagram showing another embodiment of the present invention, FIG. 2 a is an overall front view, FIG. 2 b and FIG. Figure c is a side view and plan view of the tightening mechanism shown in Figure 2a, Figure 3 is a system diagram showing an embodiment of the robot hand control system, and Figure 4 is an example of the tightening mechanism. FIG. 1: Housing, 2: Pulse motor, 3: Drive pulley, 5: Timing belt, 6: Driven pulley, 7: Feed screw, 8A, 8B: Moving piece,
9: Guide rod, 10A, 10B: Spring, 11: Chuck, 13: Moving dog, 14:
moving sensor, 15: fixed sensor, 16: moving rod,
18: Fixed rod.

Claims (1)

[Claims] 1. A motor whose rotation angle can be controlled, a feed screw driven by the motor, a moving piece that moves on the feed screw, and a spring on the moving piece that is supported via a preloaded spring. The chuck, the movement sensor attached to a part of the chuck, and the movement dog attached to a part of the moving piece move the motor to a position where the chuck can completely grasp the planned workpiece. a drive end signal generating means for outputting a drive end signal at the rotated position; and a logical operation of the signal of the drive end signal generating means and a signal issued when the movement sensor is operated by the movable dog. A robot hand characterized by having a logic circuit.