Data processing: generic control systems or specific application – Specific application – apparatus or process – Robot control
Reexamination Certificate
1998-03-16
2001-04-03
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Robot control
C700S063000, C700S258000, C318S568130
Reexamination Certificate
active
06212443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a teaching apparatus for teaching data with reference to a working point to such as an industrial robot, more particularly to a teaching apparatus which is improved in safety.
2. Discussion of the Background
As a conventional zeaching method for teaching data of a working point to an industrial robot, there is a direct teaching method, as disclosed in J.P.A. Gazette 85106/1981, in which a force sensor is provide as a teaching tool in a manual operation part of the industrial robot, each driving unit for driving an industrial robot is controlled according to directives showing positional data of a tip and attitude data of a wrist of the robot which are indicated by signals generated by the force sensor at the time when an operator operates the manual operation part to lead the position of the tip and the attitude of the wrist of the robot, and thus the data (lead data) controlling each driving unit are stored in a memory.
Further, in a method disclosed in J.P.A. Gazette 71086/1983, teaching tool
221
having a built-in force sensor is attached to the tip of robot
211
as shown in
FIG. 1
, and force control is performed corresponding to the force or the moment which is applied to teaching tool
221
, when operator
214
directly manipulates teaching tool
221
, and thus the position or the speed of the robot is controlled for leading a working tool of the robot. When performing teaching, operator
214
instructs the start and termination of teaching by manipulating many switches provided in teaching tool
221
.
Different from the direct teaching method as above, there is an indirect teaching method as shown in
FIG. 2
, in which operator
214
manipulates teaching manipulator
220
provided with manipulation switches for teaching the motion of the robot to lead robot
211
.
Conventional examples shown in FIG.
1
and
FIG. 2
each shows the same example in which cylindrical tube
213
is welded on a flat plate.
Among the conventional examples shown above, the method disclosed in J.P.A. Gazette 85106/1981 has a risk such that, if the operator stumbles during teaching and leads the teaching tool with excessive foe or makes the teaching tool contact the work or other obstruction, excess force is applied to a force detector and then abrupt motion of the robot is caused due to the excessive torque thus generated.
Or, in case the operator is caught between the arms of the robot or between the arm and the work while he is leading a teaching tool and the robot is generating power in the direction of applying force to the operator standing therebetween, it is hard for the operator to escape from this state.
Further, even when the operator detects danger during direct teaching, he will be unable to avoid the danger because he has no means at hand to suddenly stop the motion of the robot.
Still further, when the output from the force detector varies due to a temperature drift or external force is applied to the force detector, a teaching handle is not in a fixed position and there is a danger that a robot may move contrary to the operator's intention. Also when a working tool makes contact during direct teaching operation with the work or other obstruction, there is a danger that the robot may continue to move deforming the working tool. Moreover, when the operator performs the teaching of a narrow portion of the work, the teaching handle on the working tool becomes an obstrution, thereby causing a danger that the operator's arm may be grasped by the work, and further that the robot may be locked at the time of emergency stop, and in the worst case, the operator may be held in a constrained state being unable to escape therefrom.
With the robot shown in
FIG. 1
, since the operator performs teaching while manipulating many switches on the teaching tool for leading the robot, the physical/mental fatigue of the operator becomes very large. Further, when one teaching tool is commonly used among a plurality of robots, it becomes necessary to lay the wiring from the teaching tool to respective robot controllers directly thereby requiring a large cost.
Also as for the robot shown in
FIG. 2
, since the operator leads the robot per each axis or leads in the XYZ direction on the robot coordinate system or on the tool coordinate system through manipulation switches on a teaching manipulator, it is hard to intuitively lead the position or the attitude of the robot or the tool relative to the work, and the large physical/mental fatigue of the operator as well as the prolonged teaching time are required, causing a disadvantage to the person concerned.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above circumstances. A first object of the present invention is to provide a direct teaching apparatus which can control the motor generation torque within an allowable limit and enables an operator to perform teaching in safety by using a simple teaching apparatus, even if the excessive manipulation force is applied by the operator to a force detector or even if the operator is caught between arms of the robot or between the arm and the work.
Further, a second object of the present invention is to provide an apparatus for teaching a robot which can remarkably reduce the physical/mental fatigue of the operator by decreasing the number of switches on a teaching tool thereby enabling the operator to use both the direct and indirect teaching methods, the teaching apparatus being concurrently made simple with the reduced wiring.
Still further, a third object of the present invention is to provide a direct teaching apparatus which allows the operator to perform the teaching operation in safety even if there is a temperature drift in the force detector or attachment omission of a teaching handle, even if a working tool makes contact with the work or the teaching is made with reference to a narrow portion of the work or even if an emergency stop takes place.
The apparatus for teaching a robot according to the present invention comprises a force detector, a teaching tool composed of a working tool or an handle which is fixed to said force detector and held by the operator for leading the robot, a motion model operation part which serves as a means for computing a position or a speed directive based on data of said force detector and a motion model, a flexible servo system composed of means for computing motor generation torque based on said position data or said speed directive and means for controlling said generation torque, and means for storing directive data with reference to the position, speed or direction.
When the operator performs direct teaching of a working point according to the teaching apparatus structured as above by holding and leading the teaching tool and the simple teaching apparatus, the torque generated by a driving unit is controlled to a minimum amount required for the motion of the arm itself because the apparatus has a function for controlling the motor generation torque, and hence, for example, even if excessive force by the operator is applied to the force detector, there is no danger that the robot may move under the excessive generation torque. Further, even if the operator is caught between the arms of the robot or between the arm and the work, the force holding the operator is not excessively large so that the operator can easily escape by his own force, and accordingly the operator can perform the teaching operation in safety. Also, when the motor generation torque is controlled, sometimes the robot may move without corresponding to the directive data thereby producing a difference between the directive data and the detector data; however, since the apparatus comprises storage means based on the detector data, the robot can move in a playback operation to the working point actually indicated by the operator.
A apparatus for teaching a robot according to another aspect of the present invention comprises a force detector, a teaching tool composed of a ha
Inoue Yasuyuki
Morita Hirotaka
Nagata Hideo
Tanaka Youichi
Bahta Kidest
Grant William
Kabushiki Kaisha Yaskawa Denki
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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