JP2016215310A - Workpiece conveying hand comprising proximity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: a cost increases when image processing is performed by using a camera and the like, though a workpiece and a hand of a robot and the like have to be positioned in the case where the workpiece conveyed on a conveyor is gripped with the hand.SOLUTION: A proximity sensor of the present invention is attached to a hand for pick-and-place, which is typified by a robot. The proximity sensor has the function of positioning the hand so that the hand can properly grip a workpiece, by acquiring a relative position and a relative distance of the workpiece conveyed on a conveyor with respect to the hand.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a proximity sensor that detects an object to be detected relatively approaching.

Currently, a technique for detecting an object relatively close to a robot or the like (hereinafter referred to as “detected object” in the present specification) and avoiding a collision with the detected object has been researched and developed. In this specification, “relatively approaching” means that the robot moves and approaches the detected object, the detected object moves and approaches the robot, and both the robot and the detected object are It includes both cases of moving and eventually approaching.
Although detection of an object to be detected is also performed by a pigeon sensor, proximity sensors are provided around the leg of the robot and around the arm that are blind spots of the pigeon sensor.
The proximity sensor provided in the robot is described in, for example, Patent Document 1 and Patent Document 2. Patent Document 1 describes a proximity sensor that simplifies a circuit network by using a light emitting element and a light receiving element interchangeably. Patent Document 2 describes that node pairs including sensor elements are connected to a robot arm or the like in a mesh pattern, and the sensor elements are arranged along a side surface of a cylinder or the like. Patent Document 2 describes, as a comparative example, covering a robot arm or the like with a sheet-like substrate provided with a photo reflector.

JP 2007-71564 A Japanese Patent No. 5517039

However, the configurations described in Patent Document 1 and Patent Document 2 both connect a plurality of sensor elements according to the shape of a robot or the like to which a proximity sensor is attached, and integrally connect the connected sensors to a robot or the like. It is installed. For this reason, the proximity sensor described in Patent Literature 1 and Patent Literature 2 has a so-called single-product configuration that requires changing specifications (number of sensor elements, arrangement, range, etc.) according to the member to be attached. It was.
Changing the specifications for each mounted member is disadvantageous from the viewpoint of the development cost of the proximity sensor. That is, in the proximity sensor attached to the robot, it is necessary to redesign the substrate on which the sensor element is mounted for each robot having different leg and arm sizes.

  Moreover, it is a general usage method that the LED is always lit during operation, and wasteful power is consumed in a time zone when the output signal of the optical sensor is not used. Further, the optical sensor has a problem that when the object to be detected is far away, the reflected light intensity becomes low and the sensitivity of the sensor decreases, that is, the detection accuracy decreases. In addition, since the distance between the output voltage of the optical sensor and the object to be detected is in a non-linear relationship, there is a problem that conversion from voltage to distance becomes complicated. Further, although the number of optical sensors required varies depending on the purpose of use, if the control part of the optical sensor is replaced in accordance with the purpose of use, the cost increases. In addition, when the work conveyed on the conveyor is gripped by a hand such as a robot, it is necessary to position the work and the hand. However, if image processing is performed using a camera or the like, the cost increases.

  This invention is made | formed in view of such a point, and it aims at providing the proximity sensor which can respond | correspond to the various to-be-attached parts from which the cost concerning development is suppressed and size and shape differ. Another object of the present invention is to provide a proximity sensor that suppresses wasteful power consumption. It is another object of the present invention to accurately detect an object to be detected even when it is far away. The present invention also provides a simple method for converting the output voltage of the optical sensor into a distance. Also provided is a method for automatically recognizing the number of optical sensors. In addition, an inexpensive sensor for positioning the hand with respect to the workpiece conveyed on the conveyor is provided.

In order to solve the above problem, a proximity sensor according to one embodiment of the present invention is provided.
A first substrate comprising a plurality of optical sensors for detecting light intensity;
A second substrate including a distance information acquisition unit that acquires distance information between the plurality of optical sensors and the detected object based on signals output from the plurality of optical sensors on the first substrate;
And a signal transmission unit that transmits a signal generated by the signal generation unit from the first substrate to the second substrate.

In the proximity sensor according to one aspect of the present invention, it is preferable that the first substrate includes one or more optical sensor arrays in which the optical sensors are arranged in one direction.
In addition, in the above aspect, the proximity sensor according to one aspect of the present invention is based on the distance information acquired by the distance information acquisition unit of the second substrate, and the coverage sensor in the region on the first substrate where the plurality of optical sensors are arranged. It is desirable to provide a position information acquisition unit that acquires the position of the detected object.

In the proximity sensor of one embodiment of the present invention, it is preferable that the distance information acquisition unit emits light at the timing when the output of the optical sensor is captured, and is extinguished after the capture.
In the proximity sensor of one embodiment of the present invention, it is preferable that the distance information acquisition unit includes a conversion table for converting the output signal of the optical sensor into distance information.
In the proximity sensor according to one embodiment of the present invention, the microprocessor mounted on the second substrate automatically recognizes the types of various first substrates having different numbers and types of optical sensors. It is desirable to have a function of controlling a signal to be transmitted to the above-described position information acquisition unit and selecting an optimum conversion table.
In addition, the proximity sensor according to one embodiment of the present invention has a function of changing a voltage supplied to the optical sensor, and supplies a high voltage when the distance between the detected object and the first substrate is long. It is desirable to supply a low voltage when the distance to the detection object is short.

  The present invention can provide a proximity sensor that can suppress development costs and can cope with various attached parts having different sizes and shapes.

It is the figure which showed the structure of the proximity sensor which concerns on this invention. It is a perspective view of the 1st substrate. It is the figure which showed the state which connected the 1st board | substrate, the 2nd board | substrate, and the 3rd board | substrate. It is a figure which shows the relationship between the light emission pattern of LED, and the reflected light intensity which a light receiving element detects. It is a circuit diagram which shows the modification of this invention. (A) is a schematic diagram which shows the relationship between the sensor output and detection distance in a low supply voltage, (b) is a schematic diagram which shows the relationship between the sensor output and detection distance in a high supply voltage. It is a schematic diagram which shows the state which connected the 1st board | substrate of a different kind. It is a figure which shows an example of 5th Embodiment of this invention.

Hereinafter, each embodiment of the present invention will be described.
[First Embodiment]
FIG. 1 is a diagram showing an overall configuration of a proximity sensor according to the present invention. FIG. 2 is a perspective view of the first substrate 11. The first substrate 11 has a plurality of optical sensors 23 that detect the light intensity of the light reflected by the object to be detected. The first substrate 11 has a substrate 21 on which the optical sensor 23 is mounted. The board 21 is provided with a connector 27 for outputting an output signal generated by the optical sensor 23 to the outside.

  The second substrate 12 includes a microprocessor 31 that acquires output signals from a plurality of optical sensors provided on the first substrate 11. The microprocessor 31 is mounted on the substrate 35 and converts the distance between the optical sensor 23 and the object to be detected based on output signals from the plurality of optical sensors 23 provided on the first substrate 11. . The connector 27 of the first substrate 11 and the connector 37 of the second substrate 12 are connected by a flexible wiring cable 13.

  The optical sensor 23 of the first embodiment is a reflective photointerrupter, and has a configuration in which a light emitting diode (Light Emitting Diode, hereinafter referred to as “LED”) 23a and a phototransistor 23b are paired. . The LED 23a of the first embodiment is a light emitting element that emits infrared rays, and the phototransistor 23b is a light receiving element that receives infrared rays.

  The optical sensor 23 is set so that the LED 23a emits infrared light, and the infrared light emitted by the LED 23a is not received by the phototransistor 23b when there is no object to be detected. When the detected object and the robot arm are relatively close to each other, the infrared rays emitted from the LED are reflected by the detected object. The reflected infrared light is received by the phototransistor 23b. The intensity of the infrared light received by the phototransistor 23b varies depending on the distance between the phototransistor 23b and the object to be detected.

  As shown in FIG. 2, wiring is provided on the substrate 21. The plurality of optical sensors 23 and the connector 27 are electrically connected by wiring. The plurality of phototransistors 23b each generate a signal corresponding to the intensity of the received infrared light by receiving the infrared light, and transmit the signal to the second substrate through the connector 27. For this reason, 1st Embodiment can detect that the to-be-detected object approached relatively with respect to the 1st board | substrate.

  Moreover, 1st Embodiment is not limited to the above-mentioned structure. For example, in the first embodiment, an AD converter individually connected to the phototransistor 23b is provided on the substrate 21, the output of the phototransistor 23b and the like is converted into a digital signal on the first substrate, and the connector 27 is used as it is. You may make it transmit to the connector 37 and the microprocessor 31 of the 2nd board | substrate 12 via the wiring cable 13. FIG. With such a configuration, it is possible to transmit the signal to the microprocessor 31 while suppressing deterioration of the output signal of the phototransistor 23b. Communication between the first substrate 11 and the like and the second substrate 12 is performed by parallel communication in which one of the plurality of wiring cables 43 transmits an output signal of one photosensor 23.

  Further, the first embodiment is not limited to the one that transmits the output signal from the first board to the second board 12 by the wiring cable 13. In the first embodiment, the output signal of the phototransistor 23b can also be transmitted to the second substrate wirelessly. In such a case, a configuration including a communication unit for transmitting and receiving a radio signal is used for the first substrate and the second substrate.

  Moreover, the 1st board | substrate of 1st Embodiment is not limited to the structure which arrange | positions the optical sensor 23 in a line as shown in FIG.1 and FIG.2. FIG. 3 is a view showing a first substrate 611 provided with two rows of optical sensors 23.

The microprocessor 31 mounted on the second substrate 12 takes in the output signals of the plurality of optical sensors 23 on the first substrate via the connector 37. The microprocessor 31 converts the voltage that is the output signal of each photosensor 23 into the distance between the photosensor 23 and the object to be detected. Although the conversion can be performed using any calculation formula, the relationship between the intensity of reflected light received by the phototransistor 23b used in the optical sensor 23 and the distance between the phototransistor 23b and the object to be detected may be nonlinear. Many calculations may be complicated.
For this reason, the microprocessor 31 stores a conversion table representing the relationship between the intensity of the reflected light received by the phototransistor 23b and the distance between the phototransistor 23b and the object to be detected.

  The microprocessor 31 includes an AD converter and a calculation unit. When the microprocessor 31 receives the output signals of the plurality of optical sensors 23, the AD converter converts the voltage, which is an analog value, into a digital value, and then refers to the conversion table described above to convert each output signal from the voltage to the distance. Convert. The conversion table is set according to the type of the optical sensor 23. One microprocessor 31 may store one or more conversion tables. The microprocessor 31 converts the output of each optical sensor 23 into distance information and transmits it to the host control device 14.

  One or a plurality of second substrates are connected to the upper control device 14. The control device 14 interprets distance information between the individual optical sensors 23 calculated by the microprocessor 31 and the detected object, and determines the position of the detected object in the region on the first substrate 11 where the plurality of optical sensors 23 are arranged. get. That is, a plurality of distance information transmitted from a specific second substrate 12 is compared, and the most among the optical sensors 23 arranged on the specific first substrate 11 connected to the second substrate 12. By extracting the optical sensor 23 at a distance close to the detected object, position information of the detected object on the specific first substrate 11 is obtained. The control device 14 transmits the obtained position information to a higher-level control device such as a robot controller.

[Second Embodiment]
A second embodiment of the present invention will be described. In the second embodiment, the LED 23a used in the optical sensor 23 is caused to emit light only when necessary. The LED 31a is caused to emit light at the timing when the microprocessor 31 reads the output of the optical sensor 23, and is extinguished at other timings. The light emission timing is determined in consideration of the time during which the light intensity of the LED 23a is stabilized.

  After the LED 23a emits light, the microprocessor 31 confirms that the output signal of the phototransistor 23b is stabilized, and then the output of each photosensor 23 is determined. Alternatively, the time during which the light intensity of the LED 23a is stabilized is obtained in advance, and a clock signal determined in consideration of the time during which the light intensity is stabilized is transmitted from the second substrate to the first substrate, thereby controlling the periodic light emission of the LED 23a. You may do it.

[Third Embodiment]
In 3rd Embodiment of this invention, the voltage supplied to LED23a is changed according to the distance of a to-be-detected object. The optical sensor 23 has a problem that if the object to be detected is far, the reflected light becomes weak, the sensor sensitivity is lowered, and the detection capability is lowered. Therefore, when the detected object is located far from the optical sensor 23 as shown in FIG. 6B, the voltage supplied to the LED 23a is increased, and the detected object is removed from the optical sensor 23 as shown in FIG. If it is close, the voltage supplied to the LED 23a is lowered. Increasing the voltage increases the light intensity emitted by the LED 23a, and strong reflected light can be obtained even when the object to be detected is far away, so that a far object can be accurately detected.

  In this case, the optimum conversion table is also selected and used according to the supply voltage. By making the supply voltage to the LED 23a variable, it is possible to accurately detect an object to be detected in the distance, and to reduce power consumption when the object to be detected is nearby.

[Fourth Embodiment]
FIG. 7 is a schematic diagram showing the fourth embodiment of the present invention. The types of first substrates connected to the second substrate are selected from a plurality of types of first substrates having different numbers of optical sensors 23 to be mounted. A function for automatically recognizing is provided on the second substrate.
The connector 27 of the first substrate 11 and the connector 37 of the second substrate 12 are provided with pins for specifying the type of the first substrate. The figure shows the recognition method when four types of first substrates exist as an example. The connector 27 has two pins for identifying the type of the first board, and a voltage of 0 V or 3.3 V to 5 V is applied to each pin according to the type of the first board.
There are four states: (0, 0), (0, 1), (1, 0), and (1, 1), where 1 is the voltage applied to the pin and 0 is the voltage not applied. Therefore, the type of the first substrate can be automatically recognized by associating these with the type of the first substrate. A device suitable for the first substrate that also recognizes the above-described conversion table is automatically selected.

[Fifth Embodiment]
In the fifth embodiment of the present invention, the first substrate 11 is attached to the workpiece transfer hand 100 or the robot hand 101, and the hand is positioned to appropriately hold the workpiece W. FIG. 8 is a schematic diagram of a system for gripping the workpiece W flowing on the conveyor 110 without stopping the conveyor 110. The hand 100 to which the first substrate 11 is attached is brought close to the workpiece W being conveyed by the conveyor 110.

  The hand 100 approaches the workpiece W while moving rightward in FIG. 8 so as to follow the conveying speed of the conveyor 110. When the workpiece W enters the detection range of the optical sensor 23 on the first substrate 11, the hand 100 is positioned immediately above the workpiece W with reference to the positional information obtained based on the output signal of the optical sensor 23.

[Modification]
When a plurality of optical sensors 23 are mounted on the first substrate 11, the operation power may be supplied by simply branching the wiring, but the voltage may decrease as the number of branches increases. Therefore, as shown in FIG. 5, the LED 23 a may be turned ON / OFF using a light emission timing signal from a power supply taken from a common power supply line using the transistor T. Since the power supply voltage is stabilized, variations in the light intensity of the reflected light are reduced, and detection accuracy is improved.

1 proximity sensor 11 first substrate 12 second substrate,
13 Wiring Cable 14 Control Device 23 Optical Sensor 23a Light-Emitting Diode, 23b Phototransistor 31 Microprocessor

Claims (2)

A first substrate comprising a plurality of optical sensors for detecting light intensity;
A second substrate including a distance information acquisition unit that acquires distance information between a plurality of previous photosensors and an object to be detected based on signals output from the plurality of optical sensors on the first substrate;
Position information for acquiring the position information of the detected object based on the distance information acquired by the signal transmission unit for transmitting the signal generated by the signal generation unit from the first substrate to the second substrate and the distance information acquiring unit. A workpiece conveyance hand in which a proximity sensor including an acquisition unit is installed inside the workpiece gripping arm. The workpiece transfer hand according to claim 1 is made to approach from above the workpiece while following the speed of the conveyor with respect to the workpiece transferred on the conveyor, and the workpiece is moved from the optical sensor of the first substrate. A workpiece transporting method, wherein, when entering a detection range, the hand is positioned immediately above the workpiece with reference to the distance information and the position information obtained based on an output signal of the optical sensor.

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