JPH04256596A - Safety device for robot - Google Patents

Abstract

PURPOSE:To obtain a robot safety device capable of actuating a lock mechanism with the abnormality excepting the cut of the chain for moving an arm vertically being detected as well, also the lock mechanism is not actuated by mistake with the effect of an acceleration even in case of the adjustable speed of the vertical motion of the arm being increased, in a horizontal articulated robot. CONSTITUTION:A rack 12 is fitted to the vertical axis 13 of a horizontal articulated robot, a pinion 9 engaged with the rack 12 on the arm 8 of the robot, a gear 10 and sensor 11 which are coaxial with the pinion 9 and rotated integrally are provided, the measurement of the rotation of the gear 10 is executed by counting the tooth number with the crest of the gear 10 being detected by the sensor 11, the consistency of the count value thereof and the count value of the output of the encoder 15 combined with the vertical axis 13 of the robot is decided, and the lock mechanism of the robot is actuated when the consistency is lost.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a horizontal articulated robot.

0002

2. Description of the Related Art A conventional robot safety device of this type has a structure as shown in FIG.

In FIG. 4, 1 is a chain, 2 is a T-block to which the chain 1 is connected, and 3 is a sawtooth that is engaged by a ratchet 5 (described later) to lock an arm 8 (described later) when the chain 1 is cut. 4 is a spring stretched by the T block 2; 5 is a ratchet;
6 is a spring pulling the ratchet 5, 7 is a fulcrum of the ratchet 5, and 8 is an arm of the robot.

In this configuration, the ratchet 5 is pulled in the B direction by the spring 6, and the T block 2 is pulled in the A direction by the tension of the chain 1. If chain 1 breaks, T-block 2 will spring 4
, the T block 2 pushes the ratchet 5, and the ratchet 5 is pulled toward the fulcrum 7 fixed to the arm 8.
It rotates around , engages with the serrated member 3, and is locked to prevent the arm 8 from falling.

[0005]

However, with such a structure, only chain breakage can be detected as an abnormality. Further, when the acceleration and deceleration of the vertical movement of the arm is increased, there is a problem that the locking mechanism may malfunction due to the influence of the acceleration.

[0006] The present invention also provides a robot safety device that detects abnormal operations other than when the chain breaks, and that does not detect incorrect abnormal operations due to the influence of acceleration even when the acceleration and deceleration of arm movement is large. purpose.

[0007]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a rack is attached to the vertical axis of a horizontal articulated robot, a pinion that meshes with the rack is attached to the arm of the robot, and a pinion that is coaxial with the pinion is attached to the arm of the robot. A gear that rotates as one unit and a sensor are installed, and the rotation of the gear is detected by detecting the mountain of the gear with the sensor and counting the number of teeth. It is configured to determine consistency with the output count value.

[0008]

[Operation] According to the above means, the sensor detects the rotation of the pinion provided on the arm of the robot that meshes with the rack provided on the vertical axis of the horizontal articulated robot, and the gear that is coaxial with the pinion and rotates integrally with the pinion. detects, counts the output of that sensor, monitors the consistency of the count value with the count value of the output of the encoder attached to the robot's vertical axis, and controls the vertical arm movement if consistency is lost. determines that an abnormality has occurred and detects the abnormality. By activating the locking mechanism based on this abnormality detection, it is possible to prevent the horizontal arm from falling. Further, according to this means, since a mechanism that is affected by the acceleration of the arm is not used, the safety mechanism does not malfunction depending on the magnitude of acceleration or deceleration of the arm.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the attachment of an arm to the vertical axis of a horizontal articulated robot, where 8 is an arm, 9 is a pinion,
10 is a gear that rotates coaxially and integrally with the pinion 9; 11 is a sensor that detects the rotation of the gear 10; 12 is a rack that is attached to a vertical shaft and meshes with the pinion 9;
13 is the vertical axis of the horizontal articulated robot. Of the above parts, the pinion 9, gear 10, and sensor 11 are all attached to the arm 8.

In the above configuration, as the arm 8 moves up and down, the pinion 9 meshing with the rack 12 and the gear 10 coaxially integrated with the pinion 9 rotate, and the gear 1
A sensor 11 detects a mountain of 0, and a control device (not shown) counts it.

FIG. 2 is an overall view of the horizontal articulated robot. In FIG. 2, 14 is a motor for vertically driving the arm 8;
15 is an encoder for detecting the rotation of the motor 14; 16;
is a chain that transmits the power of the motor 14.

In the above configuration, when the arm 8 moves up and down normally, it follows the change in the count value of the output of the encoder 15 connected to the motor 14.
The count value of the output of the sensor 11 also changes and maintains a certain consistency. On the other hand, if an abnormality occurs in the operation of the arm 8, for example, the chain 16 may break, or the motor 1 may
If a slip occurs on the axis No. 4, the consistency between the count value of the output of the encoder 15 and the count value of the output of the sensor 11 will be lost. This loss of consistency is determined to be an abnormal occurrence, and the arm 8 is locked by a locking device (not shown) to stop the robot.

FIG. 3 shows the determination procedure. In Figure 3,
The sensor 11 detects the rotation of the gear 10 (step a),
The encoder 15 detects the rotation of the motor 14 (step b), and compares the output of the sensor 11 with the output of the encoder 15 to determine consistency between the two (step c). If an abnormality is detected, the output of the arm 8 is Lock operation (step d
)I do.

The pinion 9 may be a rubber roller, a pulley, etc. as long as it transmits rotation correctly.

Further, as the locking mechanism, there are a method of forcibly pressing a ratchet against a serrated member as shown in the conventional example, and a method of clamping a vertical shaft rail with brake pieces.

[0017]

[Effects of the Invention] The present invention improves the accuracy of the arm by ensuring consistency between the output signal of the encoder, that is, the output signal from the drive source, and the count value of the sensor output that detects the rotation of the gear that rotates with the vertical movement of the arm. Since abnormal operation is determined, it becomes possible to detect abnormalities in the arm due to causes other than chain breakage. In addition, in the conventional example, there was a risk that the locking mechanism would malfunction due to the influence of acceleration due to acceleration and deceleration of the arm, but since it does not use springs etc. that are affected by acceleration, the safety device cannot be operated due to acceleration or deceleration of the arm. There will be no malfunctions.

[Brief explanation of the drawing]

FIG. 1 is an enlarged front view of essential parts of an embodiment of the present invention for abnormality detection attached to a horizontal articulated robot.

[Figure 2]
Overall perspective view of horizontal articulated robot

[Fig. 3] Flowchart showing the procedure of abnormality determination according to the present invention

[Figure 4] Cross-sectional front view of main parts showing a conventional safety device for a horizontal articulated robot

[Explanation of symbols]

8 Arm 9 pinion 10 Gear 11 Sensor 12 Rack 15 Encoder

Claims (1)

[Claims] Claim 1: In a horizontal articulated robot, a rack is attached to the vertical axis, a pinion meshes with the rack on the arm of the robot, a gear that rotates coaxially and integrally with the pinion, and rotation of the gear is detected. A sensor, an encoder on the vertical drive part of the arm, means for determining consistency between the number of teeth of the gear detected and counted by the sensor and the output pulse of the encoder, and means for locking the arm by the output of this determining means. Equipped with robot safety equipment.