JPH0768481A - Method for teaching data to robot and robot device - Google Patents

Abstract

PURPOSE:To extremely reduce the possibility to cause personal and physical accidents by realize the positional teaching by using a non-contact displacement sensor in the condition where the tip of a robot arm is appropriately apart from the teaching point. CONSTITUTION:When the command to measure the position is given from a teaching console 38, the CPU 31 reads the laser sensor detecting signal to indicate the position of the spot beam, i.e., the distance from the reference position of measurement of a laser sensor 4 to the teaching point through an interface 37, and stores the signal in a nonvolatile memory 33 or a RAM memory 34. The information as the results of measurement by the laser sensor 4 is not sufficient as the teaching data, and it is converted into the data on the base coordinate system to be set at the position fixed on the robot working space to facilitate its use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for teaching data to a robot used for automating various operations in factories and other facilities, and more particularly to an optical device such as a laser sensor. TECHNICAL FIELD The present invention relates to a method for teaching a robot position data relating to an object or the like by using a displacement measurement means or other non-contact displacement measurement means, and an apparatus for performing the method.

The technical idea of the present invention is to apply to the entire robot system in which it is necessary to take in position data of an object, a specific point on a coordinate system, etc. in a robot work space into a robot controller and utilize the position data for internal processing. It is applicable to.

[0003]

2. Description of the Related Art When performing various works using a system including a robot, it is necessary to perform teaching for causing the robot to perform an intended operation. In order to reduce the operator's burden required for this teaching, so-called off-line teaching is used.

In this off-line teaching method, accurate data on a work object such as a work and a work environment are prepared in advance, and in the case where the work content is simple and the required robot position accuracy is not so high. It is known to be highly effective.

However, it is often difficult to completely determine the robot position based only on the data prepared during offline teaching, and in some cases it is difficult to align all required data offline. is there. Therefore, a method is often used in which the operator teaches the final position data while actually moving the robot at the work site, including the case where the offline teaching has been executed.

The teaching work by this method is usually performed by the following procedure. That is, a pointed pin-shaped member is fixed to the end effector attached to the tip of the robot arm, and the pointed pin-shaped member is operated as a teaching point by the operator's robot arm operation. Alternatively, a specific point or the like on the work is brought into contact with or close to the point of contact, and the position of each teaching point in the robot work space is calculated based on the position and orientation of each part (arm, etc.) of the robot in the contact or approach state. A method is adopted in which the teaching point data is taken into the robot system and thereafter prepared for a playback operation by a playback method or in other situations where internal processing of teaching position data is required. When such a method is adopted, it is necessary to acquire the positional relationship between the hose plate and the tip of the tip pin member in advance. In some cases, a positional relationship may be obtained by teaching a fixed point a plurality of times from different directions.

[0007]

However, when the above-mentioned touching method or quasi-touching method is adopted when acquiring the necessary position data, the following (1) to
The problem as described in (3) has occurred.

(1) Since it is necessary to bring the robot arm extremely close to the teaching point at the time of obtaining position data, a collision / scratch accident occurs between the robot arm or the end effector and the surrounding object, or soft touching fails. There is a risk of causing an accident such as damage to the pointed pin member or the work.

(2) In many cases, the operator approaches the tip of the pointed member and the teaching point so that they are close to each other or close to the point of coincidence while the operator approaches the tip of the robot arm and visually confirms the safety. There is a big problem in measures.

(3) Further, in such a teaching point touching / approaching method which often relies on visual observation, it is difficult to exactly match the tip of the pointed member with the teaching point, and some error is inevitably generated. thing.

The present invention is intended to provide a robot position data teaching method and apparatus capable of avoiding the problems of the prior art.

[0012]

According to the present invention, a step of fixedly supporting a non-contact type displacement sensing means such as an optical displacement sensor device at the tip of an arm of a robot body, and at least one non-contact type displacement sensing means. Of the teaching point, the step of executing the sensing of the teaching point by the non-contact displacement sensing means, and the teaching point of the teaching point based on the sensing result and the robot position data at the sensing time point. The above problem is solved by providing a method of teaching data to a robot, including a step of acquiring position data.

Further, according to the present invention, as a robot apparatus (robot system) having the ability to carry out the above method, a robot body, at least a robot controller for controlling the robot, and an arm tip portion of the robot body are fixedly supported. Disclosed is a robot apparatus having non-contact type displacement sensing means, and means for acquiring position data of the taught point based on a teaching point sensing result by the non-contact type displacement sensing means and robot position data at the time of the sensing. is there.

Further, according to the present invention, as a non-contact type displacement sensing means incorporated in the robot apparatus, a laser light source element, an optical system for making the output light of the laser light source element incident on an object to be inspected, and a position detecting type. Position data in a more desirable form by specifying a laser sensor device including a laser sensor means having a photodetector and an optical system for making the position detection type photodetector incident the reflected light from the object to be inspected. A robot device capable of executing teaching is proposed.

[0015]

In the method and apparatus according to the present invention, a non-contact displacement sensor is used in place of the conventional touching or quasi-touching member such as a pin, so that the tip of the robot arm can be moved at an appropriate distance from the teaching point. The position data of the teaching point is acquired by performing the sensing in the separated state. Further, at that time, it is not necessary for the operator to approach the robot arm.

Therefore, the possibility of occurrence of an interference accident or a personal injury between the robot arm or a member supported by the arm tip portion and a peripheral object is significantly reduced.

The non-contact type displacement sensing means used in the present invention is usually of a type capable of measuring the distance from the sensing means to the point to be detected, but it is a two-dimensional position displacement on a known plane. In a special case where it is sufficient to perform the above-mentioned sensing, a sensor using a single CCD camera may be used.

A typical non-contact displacement sensing means used in the present invention is an optical displacement sensor (see an embodiment described later). Currently, its operating principle is
Since a wide variety of non-contact type displacement sensors are available in terms of measurement range, measurement accuracy, price, etc., in general, if you choose any one that suits your purpose of use, you can use it. good.

Non-contact sensors other than optical sensors such as a laser displacement sensor and a camera sensor using one or more CCD cameras may be capacitance type, eddy current type or ultrasonic type displacement sensors. There are sensors, etc. For example, a capacitance sensor can measure the distance to a metal or dielectric object, and an eddy current sensor can measure the distance to a metal object. Although the distance from the object is a little small, about several mm, it has the feature that it can perform precision measurement with a resolution of several μm.

Also, the ultrasonic displacement sensor is a few 10c.
It is possible to remotely measure from a position distant from several m to several m, and a resolution of several hundred μm is easily available. For example, when the object is a transparent object for which it is difficult to apply an optical sensor, it may be advantageous to use this ultrasonic sensor.

In some cases, a plurality of or a plurality of types of sensors may be used in combination according to the sensing system of the teaching point.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the overall configuration of a robot system for carrying out the position data teaching method of the present invention. Referring to the figure, the entire system includes a robot body 1, a robot controller 3, a laser sensor 4 and a laser sensor controller 5. An end effector 2 is mounted on the tip of an arm 7 of the robot body 1, and a laser sensor 4 is fixedly supported on the tip of the end effector 2.

The robot controller 3 itself has a basically known structure, and is a memory comprising a central processing unit (hereinafter referred to as CPU) 31 and a ROM connected to the CPU 31 via a bus 39. 32, a non-volatile memory 33, a memory 34 including a RAM, an axis control unit 35 that controls a servo circuit 36 that drives each servo motor of the robot body 1, an interface 37, commands necessary for controlling the robot system, various data, and the like. It comprises a teaching operation panel 38 for inputting.

The ROM memory 32 stores various programs necessary for the CPU 31 to control the robot body and the robot controller 3 itself, and the nonvolatile memory 33 stores teaching program data of the robot. The RAM memory 34 is used as a temporary data storage means when performing teaching position calculation and the like.

Further, the interface 37 sends a control signal to the laser sensor controller 5 which controls the laser sensor 4 and processes the output signal thereof, and receives the detection signal after the signal processing, and other devices as required. It is also configured to perform the function of an input / output device for (for example, an offline program creating device).

A schematic configuration of the laser sensor 4 and the laser sensor controller 5 as the non-contact type displacement sensing means employed in this embodiment will be described with reference to FIG.

Semiconductor laser (laser diode; LD)
The light from 41 is collimated by a collimator lens 42 provided as needed, the diameter of the beam 11 is narrowed by the projection lens 43, and projected as spot light Sd on the object 6 to be inspected. . This projection spot light image is passed through a condenser lens 45 to a position detection type photodetector (hereinafter referred to as PSD).
Say ) 46 as a detection spot image on the detection surface. When the position of the test object W is displaced along the optical axis of the incident light (P → P ′), the detection spot image also moves on the PSD (Q → Q ′).

The PSD 46 having a position detecting function generates two current outputs I1 and I2 according to the incident position of the spot light, and I12 = (I1−I2) / (I1 + I
2) represents the incident position on the PSD. Therefore, the current outputs I1 and I2 are converted into voltages V1 and V2 by the current-voltage conversion circuit 53 in the laser sensor controller 5, and the calculation unit 54 calculates .DELTA.12 = (V1-V2) / (V1 + V2
) Is performed and output to the interface 37 of the robot controller 3. CPU of robot controller 3
Reference numeral 31 reads the position signal of the spot Sd which is AD-converted via the interface 37.

The laser light source element normally used in such an optical displacement measuring apparatus is equipped with a monitor light detector 49 for monitoring the output light intensity of the light source. Based on the output of the device 49, the laser light source driving circuit 51 is controlled via the laser output stabilizing circuit 52 incorporated in the laser sensor controller 5, whereby the output light intensity of the laser light source element 41 is kept constant. .

A procedure for acquiring position data for the teaching point 12 selected on the workpiece 6 using the robot system will be described below with reference to FIG.

First, the robot arm 7 is operated by jog feed to move the laser sensor 4 to a position separated from the teaching point 12 on the work 6 by an appropriate distance. Then, when a laser lighting command is sent from the teaching operation panel 38, the laser light source 41 is turned on via the interface 37 and the laser light source drive circuit 51 of the laser sensor controller 5. again,
The position or attitude of the robot arm 7 is adjusted so that the spot light Sd coincides with the teaching point 12. For this work, the robot itself or a CCD camera installed in the work space may be used while observing the monitor screen,
Further, it is also possible to add an image processor and software to construct a system for matching the spot light position Sd with the teaching point position 12 by automatic control of the robot.

When a position measurement command is issued from the teaching operation panel 38 in this state, the CPU 31 causes the interface 3
A laser sensor detection signal representing the position r of the spot light Sd, that is, the distance r from the measurement reference position S0 of the laser sensor 4 to the teaching point 12 is read via the non-volatile memory 33.
Alternatively, it is stored in the RAM memory 34.

Since the measurement result r obtained by the laser sensor is not sufficient as teaching data, it is considered to convert it to data expressed on the coordinate system which is easy to use by the robot. Here, conversion to data on the base coordinate system Σb set at a fixed position on the robot work space is performed. Now, assume that the coordinate system fixed at the measurement reference position of the sensor is the sensor coordinate system Σs, the origin of Σs coincides with the measurement reference point of the sensor, and the x-axis of Σs coincides with the laser output light direction. Also, if the posture of the measurement point is Σs
Assuming that it is the same as that of the above, the position / orientation of the measurement point viewed from the sensor coordinate system Σs is represented by the following matrix Tsd.

[0034]

[Equation 1] Here, I is a 3 × 3 identity matrix. Further, the coordinate system fixed to the end effector 2 is Σe, and the homogeneous transformation matrix for transforming the data represented on Σs into the data on Σe is Tes. Similarly, let Tbe be a homogeneous transformation matrix for Σb and Σe. Then, the robot base coordinate system Σ
In b, the position / orientation of the measurement point is expressed by the following matrix Tbd: Tbd = Tbe · Tes · Tsd (2) Coordinate system Σ fixed to the end effector
Using the coordinate system Σf fixed to the face plate at the end of the robot arm, which has a fixed relationship with e, the above equation (2)
Is given by the following equation (3).

Tbd = Tbf · Tfs · Tsd (3) By the way, among the above-mentioned homogeneous transformation matrices, Tbe or Tbf is matrix data corresponding to the position / orientation data of the robot. Further, Tes or Tfs, that is, the coordinate system Σs fixed to the measurement reference position of the laser sensor and the coordinate system Σ fixed to the end effector or face plate.
The position / orientation relationship with e and Σf can be determined by using the data described in the specifications of the laser sensor device. However, from the viewpoint of more accurate position teaching, it is desirable to perform the following teaching work for acquiring measurement reference position data.

Various methods are conceivable for obtaining the relationship between the measurement reference positions of the robot and the laser sensor (generally, non-contact displacement detecting device), but here, the laser output light of the laser sensor is set to an arbitrary value in space. Irradiate one fixed point from four or more different directions, obtain the measurement reference position data by using the measurement results at that time, and immediately teach from the measured value r of the subsequent teaching point in the base coordinate system Σb. A method of acquiring the point position / posture data Tbd will be described. First, considering the component configuration of the homogeneous transformation matrix Tbf representing the position / orientation when the face plate is viewed from the base coordinate system Σb, the following equation (4)
become that way.

[0037]

[Equation 2] Here, Rbf represents the posture of the face plate, and pbf corresponds to the portion representing the position. Further, the position / orientation of the spot light Sd is temporarily defined based on the direction of the laser sensor output light, and the position / attitude of the spot light Sd viewed from the base coordinate system Σb and the coordinate system Σf fixed to the face plate is
Letting Tbd and Tfd be homogeneous transformation matrices representing the posture, Tbf · Tfd = Tbd (5), and therefore the following equation (6) is established. Rbf · pfd + pbf = pbd (6) Here, if the position of the measurement reference point S0 of the laser sensor 4 as seen from the face plate is p0 and the unit vector of the direction of the laser output light is ds, the distance r between S0 and Sd Using
The following expression (7) is obtained. pfd = p0 + r * ds ... (7) Therefore, it becomes Rbf * p0 + r * Rbf * ds + pbf = pbd ... (8). By transforming this, the following equation (9) is obtained. In the formula I
Is an identity matrix of 3 rows and 3 columns.

[0038]

[Equation 3] Now, if the robot takes n positions and performs fixed point irradiation n times, one Tbf value and r value can be obtained for each teaching, so the i-th (n = 1, 2, ... n), the Tbf value and r value acquired by the teaching by the fixed point irradiation are represented by Tbf (i) and r (i), and the matrix A and the vectors x and b are expressed by the following equations (10) to (12). Is defined as
The equation represented by 3) will be obtained.

[0039]

[Equation 4] A · x = b (13) Here, if n ≧ 4, the above equation (13) becomes a simultaneous equation with redundancy, and its solution (least squares solution) is
It is given by the following equation (14). x = (A ^t · A) ^{over 1 · A t · b ··· (} 14) i.e., the components p0, ds of x, will be pbd is determined, the spot light positions Sd by the laser sensor subsequent As for the measurement result r, the values p0 and ds are substituted into the above equation (7), and the data p seen from the face plate is obtained.
It will be possible to convert to fd.

Therefore, each calculation program for executing the laser sensor measurement reference position teaching process described above,
Various set values are stored in the ROM memory 32 and the non-volatile memory 33 in advance, and fixed point irradiation is performed four times (or more times) while operating the robot by jog feed, and each measured value r1, r2, r3, Program calculation is executed while r4 is acquired and stored, and finally, numerical data of pfd on the left side of the above equation (7) can be executed by giving data of r, thereby making it possible to realize the present invention. The position data teachings that follow are poised to perform very efficiently.

First, a laser beam is irradiated to a point where position teaching is to be performed, the output r of the laser sensor is acquired, and the coordinate system Σ fixed to the face plate by the equation (7).
The position pfd of the teaching point viewed from f is obtained. Regarding the attitude of the teaching point, by following a predetermined method (for example, a method of locating in the attitude Rbf of Σf viewed from the base coordinate system Σb: where Rbf is a 3 × 3 rotation matrix at the upper left of Tbf) , The matrix Tfd representing the position / orientation of the teaching point viewed from the face plate is immediately obtained.

From this Tfd and position / orientation data Tbf representing the face plate of the robot, using equation (5),
It is possible to obtain the position / orientation data of the teaching point viewed from the robot base coordinate system Σb.

Therefore, finally, through the work of teaching the laser sensor measurement reference position according to the procedure described above, the formula (1
4) is calculated to obtain p0 and ds data, which are stored in the non-volatile memory 33, and a program for executing the calculations corresponding to the equations (7) and (5) is stored in the ROM 3
By loading the data in No. 2, each teaching point data selected on the work 6 or the like can be taught to the robot one after another (stored in the non-volatile memory 33).

[0044]

According to the present invention, since the position teaching can be performed with the tip of the robot arm being separated from the teaching point by an appropriate distance by using the non-contact displacement sensor, it is possible to prevent a human or physical accident. Very unlikely to cause.

Further, since the accuracy of the teaching position data is less likely to be affected by the operator's observation of the eye amount and intuition,
It is possible to teach highly accurate position data that matches the measurement accuracy of the non-contact displacement measuring device. In particular, an optical displacement sensor such as a laser sensor is easy to mount on a robot arm and has high measurement accuracy. Therefore, by incorporating this into a robot system, an extremely efficient and accurate measurement can be achieved. It becomes possible to perform position teaching.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an overall configuration of a robot system that implements a position data teaching method of the present invention.

FIG. 2 is a diagram illustrating a state in which a laser output light is irradiated to a selected teaching point on a work as an object by using the robot system shown in FIG.

FIG. 3 is a diagram illustrating a schematic configuration of a laser sensor and a laser sensor controller used in the robot system shown in FIG.

[Explanation of symbols]

 1 Robot Main Body 2 End Effector 3 Robot Controller 4 Laser Sensor 5 Laser Sensor Controller 6 Work 7 Robot Arm 11 Laser Beam 12 Teaching Point 31 Central Processing Unit (CPU) 32 Memory (ROM) 33 Nonvolatile Memory 34 Memory (RAM) 35 Axis control unit 36 Servo circuit 37 Interface 38 Teaching operation panel 39 Bus 41 Semiconductor laser (LD) 42 Collimator lens 43 Projection lens 45 Condensing lens 46 Position detection type detector (PSD) 49 Monitor photodetector 51 Laser light source drive circuit 52 Laser output stabilization circuit 52 53 Current-voltage conversion circuit 54 Operation circuit Sd Spot light

Claims (4)

[Claims] 1. A step of fixedly supporting a non-contact type displacement sensing means on an arm tip of a robot body, and a step of causing the non-contact type displacement sensing means to make a displacement capable of sensing at least one teaching point. A robot including a step of performing sensing of the at least one teaching point by the non-contact displacement sensing means, and a step of acquiring position data of the teaching point based on the sensing result and robot position data at the time of the sensing. Method to teach data to. 2. The method for teaching data to a robot according to claim 1, wherein an optical displacement sensor device is used as the non-contact displacement sensing means. 3. A robot body, a robot controller for controlling at least the robot, a non-contact type displacement sensing means fixedly supported by an arm tip portion of the robot body, and a teaching point sensing result by the non-contact type displacement sensing means. And a means for acquiring the position data of the teaching point based on the robot position data at the time of the sensing. 4. The non-contact type displacement sensing means, a laser light source element, an optical system for making output light of the laser light source element incident on an object to be inspected, a position detection type photodetector, and the position detection type. 4. The robot apparatus according to claim 3, wherein the laser sensor apparatus includes a laser sensor unit having an optical system that causes reflected light from the object to be inspected to enter a photodetector.