JPS61123905A - Driving device of moving body such as robot arm - Google Patents

Abstract

PURPOSE:To return directly a moving body in the origin returning direction in a moving area from a current stop position byproviding a discriminating sensor and anorigin return processing part for returning directly the moving body in the origin direction based on the discriminating signal of said sensor. CONSTITUTION:When an origin return instruction is now inputted to the origin return processing part 65, an origin sensor S0 is judged to turn on or not at the current stop position. When the sensor S0 is turned on, an arm is shifted in the left direction until the sensor S0 is turned off. When the sensor S0 is turned off, the arm is shifted in the direction where a subject to be detected 31 makes the right turn. Then, when the sensor S0 is turned on, a pulse Z is detected with said position P1 as a reference to judge an origin position P0, and the sensor S0 is stopped. When the sensor S0 is not turned on, the area of a part 31a is discriminated, and the arm is shifted in the left direction if the area is an area R. Then, if the sensor S0 is turned off after it turns on, the position of the part 31a is found to be at the left side from the point P1, and an origin is positioned based on the finding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Applications] The present invention relates to a driving device for a moving body, such as a robot arm, which can quickly return the moving body to its origin.

1. Explanation of Prior Art FIG. 9 shows an example of a playback type industrial rotor. The illustrated robot 1 is an example of an industrial robot having a so-called playback function that is driven in response to commands from an operating panel 3. That is, the robot 1 is operated by manual operation from the operation panel 3, and the contents of the operation are stored in a storage device (not shown), and by reproducing the stored contents of this storage device, a predetermined service such as material supply service etc. Repeat this process.

The robot 1 has an 01 axis for rotating a main shaft 7 provided on a base 5, 2 axes for vertically moving the first arm 9, an R axis for making the second arm 11 telescopic, and a 3rd axis. The arm 13 has a movable portion with a total of 5 degrees of freedom, including the θ2 axis for applying twist and the 03 axis for applying bending to the wrist 15.

Incremental encoders (not shown) are attached to each of these axes, and feedback pulse signals commensurate with the amount of movement of each axis are fed back to the servo motor drive unit of each axis from these encoders. Each axis is fi-one-hack controlled.

On the other hand, the robot 1 is provided with an origin return mode, and when restarted after a power outage or when starting teaching, the robot 1 is returned to its origin in this single origin return mode. Return to origin is
This is to stop the robot 1 from the current stop position to the origin position specified by a mechanical limit switch, etc.
-1 can thereafter be moved to a numerically commanded position based on the mechanical origin position determined in this way.

However, when the power is cut off, each axis of the robot 1 loses its current position. In this case, for example, θ1 of the main shaft 7
Although the direction of movement of the axis can be determined by determining the direction of two-phase feedback pulses, it is not possible to know in which direction the origin position is located within the movement region.

Conventionally, for example, in order to return the main shaft 7 to its origin, it is first turned in one of the two directions in which it can turn, and when a limit sensor is provided to determine the limit of the turning position, this limit sensor is set. I checked and tried to head towards the origin again.

In this case, although the main axis 7 can move toward the origin with a probability of 1/2, it will also move toward the limit sensor direction I\ with a probability of 1/2. In addition, if the limit sensor is not provided as described above, the main shaft 7 will make one full rotation and perform a roundabout return operation with a probability of 1/2. In this way, the return-to-origin operation, which has a 1/2 probability of heading toward the limit sensor side, or a 1/2 probability of going around further, requires extra operating time compared to heading directly toward the origin. Moreover, since the main shaft 7 has to perform an extra turning operation, it also increases the degree of danger, which is a problem.

The above-mentioned problems are not limited to rotating moving bodies such as the main shaft 7, but also apply to moving bodies that move in the left and right directions with respect to the origin position, for example.

In addition to the robot shown in the figure, there are similar problems with multi-jointed robots, polar coordinate robots, and other types.Furthermore, the origin is within the movement area and the servo system uses an incremental movement detector. This is a common problem for all mobile bodies that perform

LObject of the Invention] This invention is intended to improve the above-mentioned problems, and includes a driving device for a moving body that has a servo system using an incremental movement amount detector and a servo motor.
It is an object of the present invention to provide a driving device for a movable body that can directly return the movable body from the current stop position to the origin within the movement area.

[Structure of the Invention j To achieve the above object, the present invention provides a drive device for a movable body that constitutes a servo system using an incremental type movement*@detector and a servo motor, in which the movable body moves! An area discrimination sensor is provided for determining whether the sensor is located in one side or the other side with respect to the origin in the area II, and a drive unit of the small I-Y is provided with an area discrimination sensor that determines whether the area is located on one side or the other side with respect to the origin in the area II. The movable object driving vJ@ device is characterized in that it is provided with an origin return processing section that directly returns the movable object in the direction of the origin based on the determination signal.

Even if a mobile object using the above-configured control device loses its current position due to a power cut, it can use the area discrimination sensor described above to know in which direction of the origin position it is currently located. , it is possible to move directly toward the origin position without accidentally moving in a roundabout direction, and the origin position can be quickly reached.

[Explanation of Embodimentsj] Hereinafter, a preferred embodiment of the present invention will be described in detail.

Figure 1 shows a cross-sectional diagram of a servo-based robot arm (a moving body).This O-bot arm forms part of a playback type industrial robot. It is similar to that shown in Figure 9,
Although it is operated or numerically controlled by the operation panel 3, here, for ease of explanation, only one robot arm is shown as being driven.

In FIG. 1, the arm 17 is driven by a servo motor 19 via a transmission 21. As shown in FIG. The servo motor 19 is constituted by a DC motor, and is driven to rotate in both forward and reverse directions by a drive device which will be described later with reference to FIG. The transmission 21 is composed of, for example, a gear mechanism, and decelerates the rotation of one nervomotor to an appropriate rotation, and transfers the arm 17 fixed to the drive shaft 23 to the drive shaft 2.
．． 3 can be rotated in both forward and reverse directions.

The servo motor 19 is provided with an incremental encoder (movement amount detector) E (described in detail in FIGS. 3 and 4) to detect the amount of rotation of the motor 19. An arm position detection shaft 25 is provided on the rotation axis of the arm 17, and an arm position detection sensor 27 is provided at one end of this shaft 25.F indicates a frame as a fixed portion.

FIG. 2 shows an enlarged explanatory diagram of the arm position detection sensor 27 when viewed from the left side in FIG. 1.

The arm position detection sensor 27 has a sensor base 29 that is fixedly provided to the frame, and is fixed to the arm position detection shaft 25 and is rotatable while keeping its surface parallel to the two sensor bases. It consists of a detected element 31. On the sensor base 29, an origin sensor SO and limit sensors S+ and S2 for regulating the maximum swing angle of the arm 17 are arranged on the same arc, and furthermore, an origin sensor SO and an extension of the origin sensor SO are arranged on the same arc. Area discrimination sensor S3 on the line
Four sensors are arranged in an array.

These sensors So, S+, 82. Further, 83 is composed of, for example, a proximity sensor or a limit switch. On the other hand, the shape of the detected element 31 is approximately fan-shaped, the radius of which extends to the position of the area discrimination sensor S3, and only a portion of this sector has a radius that is increased to the position of the origin sensor SO. .

The detected portion 31a with a large radius becomes the detected portion of the origin sensor SO1 limit sensor S+, 82, and is the detected portion of the other fan-shaped detected portion 3.
1b becomes a detected part of the area discrimination sensor S3.

The detected portion 31a of the detected element 31 having a large radius is detected by the origin sensor SO as the arm 17 rotates. Further, the fan-shaped detected portion 31b is similar to the detected portion 31a with a large radius.
is detected by the origin sensor 3o in a region moved clockwise in the figure.

FIG. 3 shows an explanatory diagram of the incremental encoder E shown in FIG. This encoder E has a built-in rotary disk 33 that has a large number of slits 33a on the periphery and a 180 degree groove 33b inside the slit, and rotates in proportion to the rotation of the servo motor 19. This is a type of photocoupler that detects the position of iJI 33b. The signal from the Surin t-33a is output in an amount proportional to the rotational speed of the servo motor, and is used as a detection signal of the amount of movement to drive the servo motor 19 (
(described in detail in FIG. 5). The signal from the groove 33b is sent to the drive section of the servo motor 19 as a zero pulse (hereinafter abbreviated as Z-pulse) signal.

FIG. 4 is an explanatory diagram showing the signal processing method of the encoder 23 when the robot hair arm 17 returns to its origin.

Now, in FIG. 1, it is assumed that the lower end of the arm 17 rotates toward the back of the page. In this case, the detected element 3 shown in FIG.
1 rotates in the direction of arrow 31c.

Then, the origin sensor SO detects the large radius portion 31a of the detected element 31 and generates the SO detection signal shown in the upper part of FIG. 4 at 81 points. The servo motor drive unit (described in detail in FIG. 5) detects this SO detection signal, and then receives the Z pulse signal from encoder E, thereby determining that fi&Po is the origin position. . Generally, the position detection signal that is turned on and off by a proximity sensor or limit switch is itself inaccurate, and as mentioned above, the origin position is determined by the next 7 pulse signals of this position detection signal to ensure accuracy. It is expected. In addition,
Of course, it is possible to move at a relatively high speed until the origin sensor SO is turned on, and then to slow down from when the origin sensor 3o is activated, thereby accurately and quickly determining the origin. Furthermore, in this example, it is assumed that the origin positioning is performed only from the clockwise direction in FIG. 2 as described above.

FIG. 5 shows an embodiment of a υ control device for a playback type industrial robot equipped with the arm 17 shown in FIG. 1, and a driving device for a plurality of robot motors provided in this robot.

The υfill device 35 includes a central processing unit (CP), a central processing unit 37 having a 70-gram memory (ROM) and a memory (RAM), and a storage device 39 for storing taught points. , a point teaching device 41 consisting of a keyboard and various operating devices, an operating panel 43 also equipped with a keyboard and other control members, a program input device 45, and an external storage device 47 for supplementing memory storage. The operation panel 3 shown in FIG. 9 as a conventional example is a combination of the above-mentioned operation panel 43 and point teaching device 41.

The point teaching device 41 of the above-mentioned il control device W135 teaches points according to the work, the points are stored in the storage device 39, and the robot is operated for playback by the drive device described in detail below. It turns out.

Note that when teaching points, a return-to-origin operation is performed to determine the origin position of the robot.

The drive device 49 shown in the lower part of FIG. 5 has two types of drive devices 51.
．． 53, the drive device 51 is equipped with the area discrimination sensor S3 shown in FIG. 2 and three J', and the drive device 53 is not equipped with it. The main shaft 7 or the first shaft as shown in FIG.
The former drive device 51 is used for a moving object such as the arm 17 shown in the figure, which has an origin position within the movement area and receives a feedback signal from an incremental movement amount detector.
The driving unit W53 is used for a moving body having an origin position at the end of the movement area, or a servo system equipped with an absolute movement amount detector. In this example, a drive device 51 is attached to the arm 17 shown in FIG.
A drive unit is used for other moving objects (not shown)! ! 53 is used.

The drive section W151 includes a servo motor drive section 55, a servo motor 19, an encoder E that detects the amount of rotation of this servo motor (the movement of the arm 17) and returns this signal to the servo motor drive section, and the above-mentioned origin. Sensor 3o, limit sensor S+, 82, eltt and area discrimination sensor S
Consists of 3. The drive device 53 is not provided with the region discrimination sensor S3 as described above.

FIG. 6 shows a detailed block diagram of the drive device 51 shown in FIG.

The drive unit 55 of the servo motor is tllll shown in FIG.
A command data processing unit 57 connected to the ill I+ unit 35 via the bus BtJS, and a counter 59 that receives a movement command from the processing unit 57 and reduces the feedback pulse from the encoder E by the amount of the command movement 11. , until the residual value of the counter 59 becomes zero, an amplifying section 61 that applies a movement command voltage to the servo motor 19, and a speed signal is generated by making the clock pulse correspond to the feedback pulse from the encoder E to this amplifying section 61. It comprises a speed signal generation section 63 that generates a speed signal and provides the formed speed signal as a speed feedback signal, and a home return processing section 65 that operates under a home return mode.

The command data processing section 57 is connected to the central 'a' via the bus BtjS.
In addition to analyzing the command data received from the calculation processing unit 37 and issuing a normal movement amount command to the counter 59, the origin return command is given to the origin return processing unit 65 upon receiving the origin return command in the origin return mode.

The processing contents of the origin return processing section 65 are shown in FIG.

Assume that a return-to-origin command is input to the return-to-origin processing section 65. At this time, the arm 17 is currently
It is unclear where the large radius portion 31a of No. 1 is located. (See FIGS. 1 and 2) Therefore, in step 703, it is determined whether or not the origin sensor SO is on at the current stop position.

It is understood that if the origin sensor SO is on, the large-radius portion 31a of the detected element 310 in FIG. 2 coincides with the position of the origin sensor SO with a certain width.
In the figure, steps 705 and 7 are performed to direct the large radius portion 31a of the detected element 31 from the left side of the origin sensor SO.
At step 07, first, the arm 17 is moved counterclockwise (in the direction) in the m2 diagram to a position where the origin sensor SO is turned off.

If it is determined in step 707 that the origin sensor 1 So is turned off due to the movement of the arm 17 in the L direction, the process moves to step 709, where the detected element 31 rotates clockwise in the direction shown in FIG. 2 (R direction). Move the arm 17 to

Next, in step 711, when the origin sensor SO is turned on,
As already explained in FIG. 4, with this position P1 as a reference, 2 Hals is detected in step 715, the origin position PO is determined, this position Po is set as the arm origin, and step 7
Stops at 17.

On the other hand, if the origin sensor SO is not turned on in step 703, the process moves to step 721, where the large radius portion 31a of the detected element 31 is the area on the right side of the origin sensor SO (R area) in FIG. or vice versa (L12
If the area is on the right side (area R), then in step 723 the arm 17 is moved counterclockwise in FIG. 2, and in step 725 the origin sensor 3o is If it is turned on and then turned off, the process moves to step 709.

At this time, the position of the large-radius portion 31a of the detected element 31 is slightly to the left of the 11 points shown in FIG.
7 is positioned at the origin.

Further, in step 721, the large radius portion 31 of the detected element 31
If it is determined that a is on the left side of the origin sensor SO (<1 m area), the process moves to step 709, and the arm 17 is positioned at the origin by the process described above in step 717. From the above, it is clear that the arm 17 is returned to its origin directly toward the origin sensor 3o without toward the limit sensor SI or S2 shown in FIG.

Note that even if the origin sensors S1 and S2 as shown in FIG. There is no possibility of going around in a circle, and 1
This means that it is possible to return to the origin within a rotation angle of 80 degrees.

FIG. 8 shows another embodiment of the position detection sensor.

The arm position detection sensor 27 shown in FIG. 2 was for detecting the position of the rotating arm 17, whereas the
The position detection sensor 67 shown in the figure is attached to a moving body (not shown) that has its origin within the movement area and moves on a straight line.

The detected element 69 of the position detection sensor 67 is attached to a moving body (not shown) through attachment holes 69a and 69b, and the sensor base 71 has an origin sensor SO at the origin position, and
Limit sensor S+ at the limit position.

S2 is further provided with an area discrimination sensor S3 closer to the detected element 69 of the origin sensor. Then, the detected element 6
One is the origin sensor 3o or the limit sensors S1 and S2.
The detected portion 69C detected by the area discrimination sensor S
The detected portion 69d detected only at 3 is located at the origin S in the figure.
It is provided on one side of O with a length of approximately 1/2 of the total moving area.

If the movement area shown in Fig. 8 is centered on the origin position, and the right direction is the R area and the left direction is the R area, these positional relationships and the arrangement relationships of each sensor are equivalent to those shown in Fig. 2. These effects are similar to those shown in FIG.

That is, based on the origin return command, the moving body (not shown) can be directed directly toward the origin without facing the limit sensor S1 or S2, thereby making it possible to quickly return to the origin.

[Effects of the Invention] According to the present invention as described above, the movement of a moving body that has an origin within a movement area and constitutes a servo system using an incremental movement amount detector is achieved. l device, it is possible to provide a driving device for a moving body that can directly return to the origin from the current stop position under the origin return mode, for example, an industrial robot that can be safely and quickly returned to the origin. Manufacture is possible.

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention, FIG. 1 is an explanatory diagram showing a cross section of a robot arm, FIG. 2 is an enlarged explanatory diagram of an arm position detection sensor, and FIG. 3 is an encoder. Fig. 4 is an explanatory diagram of the encoder signal processing method, Fig. 5 is an explanatory diagram of the robot's v control device and drive device, and Fig. 6 is an explanatory diagram of the robot's v-control device and drive device. A detailed block diagram of the vl device, FIG. 7 is a processing flowchart of the origin return processing section, FIG. 8 is a plan view of another embodiment of the position detection sensor, and FIG. 9 is a playback type for explaining the conventional technology. FIG. 1 is a perspective view of an industrial robot. 17... Arm 19... Servo motor 27
...Arm position detection sensor 29.71--Sensor base 31.69...Detected elements 31a, 31b, 69c, 69d...Detected portion 65...Origin return processing section 51...Driver ! 114i position E...incremental encoder 3o...
Origin sensor S+, 32...Limit sensor S3...Area discrimination sensor Fig. 1 Fig. 2 wc3 Fig. 4 Fig. 5 Fig. 6 Fig. 7

Claims (1)

[Claims] In a moving object drive device in which a servo system is configured using an incremental movement amount detector and a servo motor,
An area discrimination sensor is provided for determining whether the movable body is located in one side or the other side of the movement area with respect to the origin, and the area discrimination sensor is installed in the drive section of the servo motor in a return-to-origin mode. 1. A driving device for a movable body, comprising: an origin return processing unit that directly returns the movable body in the direction of the origin based on a determination signal from the movable body.