JP3465253B2 - Robot direct teaching device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct teaching device for teaching a working point to an industrial robot or the like, and more particularly to a teaching device having improved safety.

[0002]

2. Description of the Related Art As a conventional teaching method for an industrial robot, a command value of a position of a robot tip and a posture of a wrist are calculated from a signal generated from a force detector when an operator operates a manual operation section of the force detector. A method of driving each drive device based on the command value to guide the position of the tip of the robot and the posture of the wrist, and storing the guidance information in a storage device to directly teach it (for example, JP-A-56-85106). There is).

[0003]

However, for example, when the operator guides the teaching tool with an excessive force due to a fall or the like during teaching, or when the teaching tool is brought into contact with a work or another obstacle, Since an excessive force is applied to the force detector, there is a risk that the robot will move with an excessive generated torque as a result. Also, if the operator is pinched between the arms of the robot or between the arm and the workpiece while guiding the teaching tool, it is very difficult for the operator to escape from the pinched state because the robot generates force in the pinching direction. Is. Further, when the operator judges that it is dangerous during the direct teaching, there is no means for urgently stopping the operation of the robot, which is dangerous for the operator. The present invention has been made in view of the circumstances as described above, and even when an excessive operating force of the operator is applied to the force detector or when the operator is sandwiched between the arms or between the arm and the work, it is unnecessary. It is an object of the present invention to provide a direct teaching device that allows an operator to safely teach by limiting the torque generated by the motor and using a simple teaching device.

[0004]

To achieve the above object, according to the solution to ## in the teaching device of the present invention as shown in Figure 1, the force detector 21 is fixed to the detector operator piece
A teaching tool 20 including a work tool 22 or a dedicated handle 23 for gripping and guiding with a hand, and a motion model calculation unit 24 that is a means for calculating a position or speed command based on the force detector information and a motion model. And a flexible servo system 25 composed of a means for calculating a generated torque of a motor based on the position or speed command and a means for limiting the generated torque to an operable range of the arm, and a position / speed or direction command It has means 29 for storing information.

[0005]

With the teaching device configured as described above, a mechanism is provided for limiting the torque generated by the motor when the operator holds and guides the teaching tool and the simple teaching device to directly teach the working point. Since the torque generated by the drive part is limited to the minimum amount necessary for the arm itself to operate, the robot will generate excessive torque even if the operator's excessive force is applied to the force detector. Eliminates the risk of exercising. Further, even if the operator is caught between the arms or between the arm and the work, the operator can easily escape without being caught with an excessive force, and the teaching work can be performed safely. In addition, although the robot may not operate according to the command information and the command information may deviate from the detector information by limiting the torque generated by the motor, the storage of the detector information may cause the robot to play back during playback. Can actually move to the work point taught by the operator.

[0006]

EXAMPLES Examples of the present invention will be described below. First, a simple teaching device used as an auxiliary for the direct teaching of the present invention will be described with reference to FIG. The simple teaching device 40 has the size of a palm and can be operated by an operator with one hand to operate each switch (the other hand of the operator must be held with one hand to hold a teaching tool described later). Servo power supply holding switch 41,
The emergency stop button 42, the input switch 43, the stored information edit key 44, and a status indicator 45 are also provided. The operator 11 can turn on the servo power by holding the servo power holding switch 41 with a constant force. Further, when the operator 11 judges that it is dangerous during the direct teaching work, the operation of the robot can be stopped by releasing the servo power source holding switch 41 or pressing the emergency stop button 42. The input switch 43 is
It is a switch that takes in the position of the robot at that time only when it is pressed, and this input switch 43 is pressed every time the teaching at each teaching point is completed. The stored information edit key 44 is used for editing such as addition, change and deletion of stored information. This makes it possible to replace teaching points. The status display lamp 45 is a lamp that displays that teaching is in progress.

FIG. 2 is a block diagram of a control system showing an embodiment of the present invention. As a control method, an inductive force of the teaching tool 22 gripped by the operator is detected by the force detector 22, and a motion model calculation unit 24 based on this force detector information and a motion model based on virtual inertia and viscosity is used for the orthogonal coordinate system. Position command is calculated. This position command is inversely transformed into the joint coordinate system to obtain the joint angle command for each joint. The torque generated by the motor in the flexible servo system 25 is calculated based on the joint angle command and the joint angle and joint velocity detected by the joint angle detector 32 provided in each drive portion or each joint portion of the robot. Here, the torque limiter 26 is connected to the robot 12
Set the minimum torque limit value required to operate the arm. By inputting the generated torque to the torque limiter 26, the generated torque is suppressed within a safe range.
Here, for example, when the operator applies an excessive operating force to the teaching tool 20, the generated torque is limited to the minimum torque required to operate the arm of the robot 12. Furthermore, the torque generated after this torque limitation is
Friction compensation is performed based on the angle of each joint, the distance from the center of gravity of each arm to the center of each joint, and the gravity compensation torque acting on each arm calculated in the gravity compensator 30 from the mass of each arm, and the joint velocity of each joint. The compensation torque of the friction acting on the driving portion of each joint calculated in the device 31 is added. The robot 12 is driven by the generated torque after this addition. The operator guides the robot 12 to the work point on the work target 14, and the input switch 4 provided on the simple teaching device 40.
By pressing 3, the joint angle command is stored in the information storage unit 29. During playback, position control is performed based on the stored joint angle command.

FIG. 3 shows another embodiment, which is an example in which the joint angle detection value detected by the joint angle detector 32 is stored in the information storage unit 29 and played back instead of the joint angle command. This feature is that the torque is limited and the generated torque of the motor becomes insufficient, so that the robot 12 does not operate according to the command information and the command information and the detector output information deviate from each other. If command information is stored in the information storage unit 29 (FIG. 2) in this state, the robot 12 will move to a position deviated from the actual teaching point during playback. Therefore, by providing the information storage unit 29 (FIG. 3) for the detector information, the robot can move to the work point when the input switch is actually pressed during playback. Whether to store the command information (FIG. 2) or the detector information (FIG. 3) may be selected on a case-by-case basis. Therefore, a selection switch for selecting which one to select may be added on the simple teaching device 40.

4 and 5 show an embodiment of the welding operation of the direct teaching method for a robot according to the present invention. The operator 11 attaches and fixes the teaching tool 20 to the wrist portion of the robot 12 or the like, and then holds the servo power holding switch 41 on the simple teaching device 40 to turn on the servo power. The operator 11 grasps the dedicated handle 23 fixed to the force detector 21 as shown in FIG. 4 and guides it in an arbitrary direction, or the working tool 22 fixed to the force detector 21 as shown in FIG. The welding torch is held and the robot 12 is guided in an arbitrary direction to teach the work point on the work target 14. The information from the force detector 21, the command from the simple teaching device 40, and the information from the joint angle detector 32 attached to each drive shaft of the robot 12 are fetched by the robot controller 13 and processed there. , Robot 1
Issue a command to drive 2.

[0011]

As described above, according to the industrial robot direct teaching apparatus of the present invention, the torque generated by the drive portion is limited to the minimum necessary for the arm itself to operate, Even if the operator's excessive force is applied to the force detector, there is no danger of the robot moving with excessive torque.In addition, even if the operator is caught between the arms or between the arm and the workpiece, it will not be necessary. Without being caught, it can be easily escaped by human power, and teaching work can be performed safely. In addition, by having the servo power supply holding switch in the simple teaching device that the operator holds separately from the teaching tool, it is possible to arbitrarily stop the operation of the robot according to the operator's judgment.

[Brief description of drawings]

FIG. 1 is a block diagram showing the concept of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram showing an embodiment of the present invention.

FIG. 4 is a perspective view of a welding operation showing an embodiment of the present invention.

FIG. 5 is a perspective view of a welding operation showing another embodiment of the present invention.

FIG. 6 is a front view of a simple teaching device showing an embodiment of the present invention.

[Explanation of symbols]

11 ... Operator 12 ... Robot 13 ... Controller 14 ... Work object 20 ... Teaching tool 21 ... Force detector 22 ... Working tool 23 ... Dedicated handle 24 ... Kinematic model calculation unit 25 ... Flexible servo system 26 ... Torque limiter 29 ... Information storage device 30 ... Gravity compensator 31 ... Friction compensator 32 ... Joint angle detector 40 ... Simple teaching device 41 ... Servo power supply holder 42 ... Emergency stop button 43 ... Input switch 44 ... Memory information edit key 45 ... Status indicator light

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B25J 9/22 B25J 13/00 G05B 19/42

Claims (3)

(57) [Claims] 1. A direct teaching device for a robot, a force detector and a teaching tool fixed to the force detector for allowing an operator to hold and guide with one hand, or a teaching tool comprising a dedicated handle, and the force detector. Means for calculating a position or speed command based on the device information and a motion model, means for calculating a torque generated by a motor for driving the robot based on the position or speed command, and angles of joints of the robot
And the distance from the center of gravity of each arm to the center of each joint and
Compensation torque of gravity acting on each arm from the mass of the arm
Acts on the driving part of each joint from the joint velocity of each joint
A direct teaching device for a robot, comprising: means for limiting the generated torque within a range in which the arm can operate by compensating for a friction compensation torque . 2. Separately from the teaching tool, at least
Servo power that can turn on / off the power to drive the bot
A switch and a robot taught using the teaching tool
It has an input switch for inputting information about the position of
A simple teaching device operated with one hand is provided.
The direct teaching device for a robot according to claim 1. 3. Based on the force detector information and a motion model
Either store the calculated position as teaching data, or actually
The position when teaching by moving the robot is used as teaching data.
It has a special switch that can be stored in memory or selected.
Direct teaching device for a robot according to claim 1 or 2
Place