JPS63260779A - Direct teaching control system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] This invention is a direct teaching control method for a robot that has a force sensor that detects the force applied to the hand, and teaches the robot by moving the hand in the direction of the force applied to the hand. If the stooge enters the range of the singularity when doing so, Locus I! ! In order to solve the problem of the robot's hand moving rapidly due to the excessive velocity signal near the singularity that occurs when the robot moves near the singularity, we have set the robot's hand movement control in advance when the robot's hand enters the vicinity of the singularity. By performing predetermined control, for example, controlling the robot to stop, it is possible to directly teach the robot by holding its hand without causing sudden movement in the vicinity of the singular point.

[Industrial application field]

The present invention provides direct teaching control configured to prevent rapid movement by stopping the movement of the hand when the hand enters the range of the singularity in a robot having a singularity, such as an articulated robot. It is related to the method.

[Problems to be solved by conventional technology and invention] Conventionally,
Teaching play bank type robots are used in many industrial robots. In this case, so-called direct teaching, in which the operator holds the robot's hands and teaches while moving the robot, teaches the teaching points easily, but in order to turn off the power to the robot's actuators, the operator has to move the heavy robot. However, it was not easy to use, and it placed an excessive burden on the user. For this reason, a force sensor is installed to detect the force applied to the robot's hand, and when the operator applies (or pulls) a small amount of force to this sensor, the force sensor detects the direction of the applied force. However, there is a method that allows the robot to move in the direction of this detected force. This method is for an orthogonal robot, and the robot only needs to be moved by applying signals in the X, Y, and Z directions detected and output by force sensors to the corresponding actuators.

However, when this method is applied to an articulated robot, the velocity signal becomes excessive (infinite) near the singular point that occurs during coordinate transformation, which is unique to an articulated robot. There is a problem in that the operator with the hands is forced to move suddenly.

This rapid movement of the hand will be explained in detail using FIGS. 7 and 8, taking the scalaropont as an example.

FIG. 7 is viewed from directly above, with 21 representing the first arm, 22 representing the second arm, and θ1 and θ2 representing their respective rotation angles. Note that the rotations around two axes and the Z axis, which a normal SCARA robot has, are omitted. Here, the singular point occurs when the first arm 21 and the second arm 22 are in a straight line, that is, when θ2=0. To be more specific, the velocity signal vector intersection detected and generated by the force sensor is a rectangular coordinate system, and the equation for converting this into the angular velocity vector θ of the joint is expressed by the following equation.

θ=J-1・X・・・・・・・・・・・・・・・(1) Here, J-1 is the inverse matrix of the Jacobian matrix determined by the structure of the robot. Represented as shown.

Therefore, as is clear from the equation for J-1 shown in Fig. 8, each element of J-1 becomes infinite near the singular point θ*-0', and excessive angular velocity vectors are generated. Sisters,
There is a problem in that the robot's hands are moved rapidly, giving the operator a sense of unease.

In addition, in recent years, robot control using high-speed digital signal processors has been proposed, but the word length that can be processed by these processors is finite, and this causes accuracy degradation (digit loss due to fixed-point arithmetic). Not necessarily θ2=0
There is a problem in that the same situation as a singularity is created not only at ° but also in the vicinity.

Therefore, an object of the present invention is to prevent these operators from unintentionally putting the robot's hands near the singularity point, generating excessive speed, and causing a sense of anxiety.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention includes a force sensor 4 that detects the direction of the force applied by the teacher when the teacher holds the hand of the articulated robot and moves it for teaching, and A robot controller 1 that moves the hand based on the direction of force, and when the hand moved by this robot controller 1 enters the range of a predetermined singularity, the control of the movement of the hand is switched to the predetermined control. That's what I do.

FIG. 1 shows a basic configuration diagram of the present invention, and FIG. 2 shows a conceptual diagram of the present invention. In the figure, a robot controller 1 moves an arm 3 in the direction of a force detected by a force sensor 4.

The encoder 2 detects the angle of the arm 30.

The arm 3 is rotatably attached,
This is equivalent to the arm of an articulated robot such as Surakarobosoto. Arm 3-1 represents a first arm, and arm 3-2 represents a second arm.

The force sensor 4 detects the force applied (or pulled) to the tip of the arm 3 by the instructor.

The servo L-1 controls a motor (not shown) to move the arm in the direction of the force detected by the force sensor 4.

[action] Next, the operation will be explained using FIGS. 1 and 2.

In FIG. 2, the diagonally shaded range is the range preset as the vicinity of the singular point. When the tip of the arm (second arm) 3-2 rotatably connected to the arm (first arm) 3-1 is pushed (pulled) by the operator, this force is detected by the force sensor 4. The hand is moved as shown by the dotted arrow in the figure by the servo 1-1. At this time, if it is determined based on the angle signal detected by the encoder 2 that the robot controller 1 has entered the shaded range, the robot controller 1 stops the movement of the hand, for example. Then, when the object moves outside the diagonally shaded area, it is moved again.

As described above, when the hand of an articulated robot enters the vicinity of a predetermined singularity point, the hand movement is stopped, and when a force directed outside the vicinity of the singularity is detected, the hand moves again. By controlling the robot to do so, it is possible to prevent the robot's hands from making sudden movements when they enter the vicinity of the singularity.

〔Example〕

Next, the configuration and operation of one embodiment of the present invention will be explained in detail using FIGS. 3 and 4.

In FIG. 3, the robot controller 1 is a control device using a digital signal processor or the like that performs processing at a high speed sampling time.

The encoder 2 detects the angle of the arm 3.

The force sensor 4 is a six-axis sensor or the like that detects forces in the X, Y, and Z axis directions and moments around each axis that are applied (or pulled) to the tip of the arm 3.

The force signal processing unit 5 calibrates the signal detected by the force sensor 4 when the operator holds and moves the robot's hand, and converts the coordinates to the direction of the force applied to the robot's hand. Corresponding speed signal
It is something that causes.

J-'6 multiplies the velocity signal X by the inverse Jacobian matrix J-1, converts it into the angular velocity of the joint, etc., and inputs it to the function generator 7.

Function occurs! S7 generates, for example, a trapezoidal speed signal for driving the arm 3 based on the input angular velocities of the joints, supplies it to the servo 1-1, and controls the speed of the arm 3 by driving a motor (not shown). It is something.

Through the above procedure, the robot's hand moves in the direction in which the operator pushes (pulls) the robot's hand.

Next, a detailed description will be given of the operation in which the robot's hand enters the diagonally shaded region, that is, the vicinity of the singular point explained using FIG. 2, and the movement of the hand is stopped.

The current position calculation unit 8 in FIG. 3 calculates the current position X expressed in a rectangular coordinate system based on the rotation angle e of the arm 3 detected by the encoder 2.

The comparison unit 9 compares the current position 1)1FX calculated by the current position calculation unit 8 with the set singularity range (X a)10
That is, it is determined by comparing whether or not it is within the shaded range in FIG. If it is determined that the current position X is not within the set singularity range 10, the command signal is not notified to the force signal processing unit 5, so direct teaching is executed. On the other hand, if it is determined that the current position '6 to stop the movement of arm 3.

The operation of the present invention will be explained in detail using FIG.

In FIG. 4, ■ indicates a state in which the joint angle is read from the sensor. This is encoder 2 connected to arm 3.
This means reading the joint angles θ1 and θ2.

■ in the figure indicates a state of conversion to orthogonal coordinates. This means that the current position calculation unit 8 in FIG. 3 calculates the current orthogonal coordinate value ix based on the joint angles θ1 and θ2 input via the encoder 2) and the servo 1-1.

In the figure, ■ indicates a state in which a comparison is made to see if the value is within the set value. This means that the comparator 9 in FIG. 3 compares and determines whether the current orthogonal coordinate position X calculated at 3 in the figure is within the set singularity range 10. In the case of YES, the area is located within the shaded area in FIG. 2, so the steps below (■) in the figure are executed. N.

In this case, since the robot is located outside the shaded area in FIG. 2, the operator teaches the robot by pushing or pulling the hand, and repeatedly executes steps (1) and (2) in the figure.

■ in the figure indicates a state in which the robot stops moving.

This is indicated by ■ in the figure, and it was found that it was located within the shaded area in FIG. 2, so the comparator 9 in FIG. -16 to stop the movement of the arm 3.

In the figure, ■ indicates a state in which it is determined whether or not the hand is being pushed (or pulled). This means determining whether a force is applied (or pulled) to the force sensor 4 or not.

In the case of YES, perform ■ in the figure. In the case of NO, repeat the process ■ in the figure.

In the figure, ■ indicates a state in which it is determined whether or not the movement is outside the range. This means that it is determined whether or not the direction in which the hand moves when the force sensor 4 is pushed (or pulled) is outside the shaded area in FIG. YE
In the case of S, move the robot's hand again at ■ in the figure.

In the case of No, step 3 in the figure is repeatedly executed and the force sensor 4 is stopped and stands by until the force sensor 4 is pushed (or pulled) outside the shaded area in FIG.

As described above, when the robot's hand enters the shaded area (near the singularity) in Figure 2, the movement of the hand is stopped and force is applied to the force sensor 4 in the direction outside the vicinity of the singularity. By moving the hand again, the hand is prevented from moving at excessive speed near the singularity.

FIG. 5 shows a configuration diagram of another main part embodiment.
The sword body name processing unit 5 is replaced with the configuration shown in the figure, and the robot hand is shown in the diagonal line (near the singularity) in Figure 2.
If the user enters the room, the movement of the hand is controlled to return to the original direction based on the notification from the comparison unit 9. This allows the operator who is teaching the robot's hands to
When the hand receives a force that moves in the opposite direction, it becomes possible to know that it has entered the vicinity of the singularity, and to teach in a manner to avoid this area. The configuration and operation will be explained below.

In FIG. 5, when the robot's hand is outside the vicinity of the singularity, the velocity vector calculation unit 5-2 generates the velocity X based on the direction and magnitude of the force F notified from the force sensor 4,
is notified to J-'6 as the speed X via the switch 5-6. This allows the instructor to push the robot's hand (
The hand is controlled to be moved in the direction (pulling). On the other hand, when the robot's hand enters the vicinity of the singularity, the switch 5-6 is switched to the right side based on a command signal from the comparator 9. Then, for example, the high velocity sampled immediately before entering the vicinity of the singularity stored in the storage register 5-3 is read out by the reading unit 5-4, and the velocity whose sign is inverted by the sign inverting unit 5-5 is read out by the reading unit 5-4. - alternation is notified to J-+6 as high speed via the switch 5-6. As a result, if the object enters the vicinity of the singularity, it will be returned to the direction immediately before entering.

FIG. 6 shows a configuration diagram of another main part embodiment.
The sword body name processing unit 5, J-'6, and function generator 7 are replaced with the configuration shown in the figure, and when the robot's hand enters the diagonal line (near the singularity) in Figure 2. Based on the notification from the comparison unit 9, only the angle θ2 of a predetermined arm, for example, the second arm 3-2 in FIG. As a result, the operator who is teaching the robot's hand will be able to know that the hand is receiving a force that moves in almost the opposite direction and has entered the vicinity of the singularity, and will be able to teach the robot in a manner that avoids this area. Note that since only the second arm 3-2 is rotated to avoid entering the vicinity of the singularity, there is no need to perform processing using an inverse Jacobian matrix in this embodiment.The configuration and operation are described below. explain.

In FIG. 6, when the hand of the robot is outside the vicinity of the singularity, the velocity vector calculation unit 1)-1 generates the velocity large based on the direction and magnitude of the force F notified from the force sensor 4. J-'6 as a major, and furthermore, this J-16
The angular velocity .theta. converted by .theta. is notified to the function generator 7 via the switch 1)-4. This controls the robot's hand to move in the direction in which the teacher pushes (pulls) the robot's hand. On the other hand, when the hand of the robot enters into the vicinity of the singularity, the switch 1)-4 is switched to the right side based on the command signal from the comparator 9. and,
For example, the second arm angle θ2 sampled immediately before entering the vicinity of the singular point stored in the storage register 1)-2 is read out from the storage register 1)-2 and notified of the angular velocity generating unit 1)-. 3 generates an angular velocity δ2 in the direction outside the vicinity of this singularity, and notifies it to the function generator 7 via the switch 1)-4. At this time, a signal of zero angular velocity is notified to the function generator 7 for the angular velocity θ of other arms, etc. As a result, when the hand of the robot enters the vicinity of the singularity, the second arm rotates and is returned to the outside of the vicinity of the singularity.

In addition, since this embodiment uses a digital signal processor for processing, it is configured so that all processing can be executed within a sampling time of 1 ms. Also, if the robot's hand enters the vicinity of the singularity by a maximum Q of 1 mm (the shaded area in Figure 2), it will stop, return to its original direction, or move only the second arm out of the vicinity of the singularity. This allows the operator to move the hand quickly, without making the operator feel uneasy about the sudden movement of the hand. Also, if you want to move the robot's hand beyond the range near the singularity to the other side, you can use the second
The first arm 3-1 and the second arm 3-2 in the figure may be bent and moved to avoid the vicinity of the singular point.

〔Effect of the invention〕

As explained above, according to the present invention, when the hand of the robot enters the vicinity of a singular point, the movement of the hand is controlled by a predetermined control, for example, to stop. Even a robot with a singularity, such as an articulated robot, can be taught directly without causing sudden movements of the robot's hands.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a diagram of the principle configuration of this embodiment, Fig. 2 is a conceptual explanatory diagram of the present invention, Fig. 3 is a diagram of the configuration of one embodiment of the present invention, and Fig. 4 is a diagram of the configuration of an embodiment of the present invention. FIG. 5 and FIG. 6 are flowcharts for explaining the operation, FIG. 5 and FIG. 6 are configuration diagrams of other main parts of the present invention, FIG. 7 is a diagram for explaining the operation of the conventional system, and FIG. 8 is an example of the J bow value. In the figure, 1 is a robot controller, 1-1 Hasabo,
2 is an encoder, 3 is an arm, 4 is a force sensor, 5-2.
1)-1 is a speed vector calculation unit, 5-3.1)-2 is a tα register, 5-4 is a readout unit, 5-5 is a sign inversion unit, 5-6.1)-4 is a switch, 1)-3 represents an angular velocity generation section.

Claims (4)

[Claims] (1) In the direct teaching control method of a robot that has a force sensor that detects the force applied to the hand, a force sensor that detects the direction of the force applied when the teacher moves the robot's hand while trying to teach by holding the robot's hand (4) and a robot controller (1) that moves the hand based on the direction of the force detected by the force sensor (4), and a robot controller (1) that moves the hand within a predetermined singularity range. 1. A direct teaching control system characterized by being configured to switch hand movement control to a predetermined control when an intrusion occurs. (2) A direct teaching control system characterized in that switching to the predetermined control described in claim (1) is switched to stop control. (3) A direct teaching control system, characterized in that switching to the predetermined control described in claim (1) is switched to control movement in a direction outside the range of the singular point. (4) A direct teaching control system, characterized in that the switching to the predetermined control described in claim (1) is switched to control movement in the original direction outside the range of the singular point.