JPWO2018131237A1 - Collaborative robot system and control method thereof - Google Patents

Abstract

The present invention provides a collaborative robot system that can perform a work operation or a movement operation at a higher speed than the conventional one, and a control method thereof. In a collaborative robot system that includes a robot arm (1) and allows an operator to approach the robot arm, a plurality of proximity sensors (2) that are attached to the robot arm and detect the approach of the operator to the robot arm; And an arm control unit (5) for selecting a proximity sensor used for worker detection from a plurality of proximity sensors according to the work procedure of the arm.

Description

  The present invention relates to a collaborative robot system in which a robot arm and a worker perform work in the same work space, and to a control method for the collaborative robot system.

When the robot arm and the worker collaborate, conventionally, the safety of the worker is divided by dividing the work range between the robot arm and the worker using a light curtain or a physically configured safety fence. It was achieved.
In recent years, in order to improve work efficiency, it is becoming mainstream to make a robot arm and a worker approach each other and collaborate. In order to ensure the safety of the worker in this case, a method has been devised in which a proximity sensor is provided on the robot arm itself to detect the approach of the worker.

  This system has one or more proximity sensors that cover the robot arm in a wide range, and detects obstacles such as an operator in the operation path of the robot arm. When the danger of interference between the robot arm and the worker is detected, the operation of the robot arm is immediately stopped or the operation path of the robot arm is changed so as to avoid the worker or the like (Patent Document 1). reference).

JP 2009-233757 A

In Patent Document 1, for each link of a manipulator in a robot and surrounding objects, a sphere whose outer shape is enveloped is set, and interference determination is performed only by calculating the center-to-center distance of each sphere accompanying the operation of the manipulator. . This simplifies and speeds up the arithmetic processing.
On the other hand, since the operation path of the robot arm is changed or the movement is stopped according to the worker detection by the proximity sensor, the plurality of proximity sensors need to be constantly operated to detect the worker. Therefore, when the number of proximity sensors increases, there is a problem that the processing waiting time for worker detection increases and the movement speed or work speed of the robot arm decreases.

  The present invention has been made to solve the above-described problems, and in a collaborative robot system in which a robot arm and an operator work close to each other, a work operation or a movement operation can be performed at a higher speed than before. An object of the present invention is to provide a collaborative robot system and a control method for the collaborative robot system.

In order to achieve the above object, the present invention is configured as follows.
That is, a collaborative robot system according to an aspect of the present invention includes a robot arm, and the collaborative robot system in which an operator can access the robot arm is attached to the robot arm, and the worker approaches the robot arm. And a plurality of proximity sensors for selecting a proximity sensor used for worker detection from the plurality of proximity sensors in accordance with the work procedure of the robot arm.

  According to the collaborative robot system in one aspect of the present invention, since the arm control unit that selects the proximity sensor is provided, it is possible to specify the proximity sensor necessary for the detection of the operator. That is, it is not necessary to obtain the worker detection information from all the proximity sensors, and the proximity sensor detection information necessary for the worker detection can be reduced. Therefore, the processing waiting time by the proximity sensor can be shortened. As a result, the approach of the worker to the robot arm can be detected more quickly and reflected in the next work operation, so that the robot arm can be operated or operated at a higher speed.

It is a figure which shows schematic structure of the cooperation robot system in Embodiment 1. FIG. It is the perspective view which showed the arrangement position and orientation about the proximity sensor installed in the link of the robot arm shown in FIG. FIG. 2 is a system block diagram assuming hardware and software implementation in the collaborative robot system shown in FIG. 1. FIG. 2 is a diagram showing a coordinate system for calculating a moving speed vector from a change in position coordinates of a robot arm in the collaborative robot system shown in FIG. 1. In the collaborative robot system shown in FIG. 1, the robot control module, the human detection module, and the sensor ECU are sequence diagrams for sharing information using a shared memory. It is an operation | movement flowchart of the cooperation robot system shown in FIG. It is a figure which shows schematic structure of the cooperation robot system in Embodiment 2. FIG. FIG. 8 is a characteristic diagram showing the relationship between the reception electric field strength of the LF charging wave of the wireless tag and the reception distance in the cooperative robot system shown in FIG. 7. FIG. 8 is a diagram illustrating the received electric field strength of the wireless tag obtained from the first antenna and the received distance of the wireless tag at the received electric field strength in the cooperative robot system shown in FIG. 7. FIG. 8 is a diagram showing the received electric field strength of the wireless tag obtained from the second antenna and the received distance of the wireless tag at the received electric field strength in the cooperative robot system shown in FIG. 7. FIG. 8 is a diagram illustrating the received electric field strength of the wireless tag obtained from the third antenna and the received distance of the wireless tag at the received electric field strength in the cooperative robot system shown in FIG. 7. FIG. 8 is a schematic diagram for explaining position estimation of a wireless tag from reception distances of wireless tags obtained from three antennas in the collaborative robot system shown in FIG. 7.

  A collaborative robot system according to an embodiment and a control method of the collaborative robot system will be described below with reference to the drawings. In each figure, the same or similar components are denoted by the same reference numerals. In addition, in order to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art, a detailed description of already well-known matters and a duplicate description of substantially the same configuration may be omitted. . Further, the contents of the following description and the accompanying drawings are not intended to limit the subject matter described in the claims.

Embodiment 1 FIG.
A human collaborative robot (hereinafter referred to as a “collaborative robot”) is a work system in which an operator can work closer together with a robot arm so that the worker can work with the robot arm. In such a collaborative robot system, proximity sensors of various detection methods are installed in the robot arm itself in order to improve the work efficiency when the worker approaches and moves away from the robot arm and to ensure the safety of the worker. Consideration is being made.

FIG. 1 shows a schematic configuration of a collaborative robot system 101 according to the embodiment. The collaborative robot system 101 includes, as basic components, a robot arm 1, a proximity sensor (non-contact sensor) 2 that is attached to the robot arm 1 and detects the approaching and leaving of an operator, and an arm control unit 5. With. As will be described in detail later, the arm control unit 5 is a part having a function of selecting a proximity sensor 2 to be used for worker detection from a plurality of proximity sensors 2 in accordance with the work procedure of the robot arm 1.
The collaborative robot system 101 is further based on the environmental sensor 3 that detects the entry / exit of the worker to / from the work space, the detection information of the proximity sensor 2 selected by the arm control unit 5, and the detection information of the environmental sensor 3. A sensor processing unit 4 for obtaining the position of the worker can be provided.
Hereinafter, each of these components will be sequentially described.

  As shown in FIG. 1, the robot arm 1 in this embodiment refers to the entirety of each link 1 a-1 f including joints, and corresponds to, for example, a 6-axis articulated robot capable of complicated work. Drive device). On the other hand, the robot arm 1 is not limited to an articulated robot, and corresponds to a robot capable of cooperating with an operator. The links 1a to 1f are constituent elements of the robot arm 1 including joints in the robot arm 1.

  A plurality of proximity sensors 2 are installed on the surface (including the surface of the joint portion) of some or all of the links 1a to 1f constituting the robot arm 1, and detect an operator approaching the robot arm 1. In the collaborative robot system 101 in this embodiment, the proximity distance of the worker is assumed to be 5 m to 0 m, but is variable depending on the performance of the proximity sensor 2 to be used. As the proximity sensor 2, an ultrasonic sensor, an optical sensor, a capacitance sensor, a radio wave sensor, or the like can be used, and a distance sensor that can measure a distance from an operator is used. When a pyroelectric sensor that detects human far-infrared radiation is used as an optical sensor, a sensor capable of measuring the distance to the person may be used in combination.

  In the present embodiment, the proximity sensor 2 is installed at the tip of one or a plurality of links having a particularly high moving speed, but is installed at a position defined by the specifications of the robot arm 1 on the link surface or joint. Further, the proximity sensor 2 is used after being calibrated so that the arm controller 5 can be operated, such as the detection distance, detection sensitivity, detection time, and detection direction, depending on the installation position of the proximity sensor 2.

  FIG. 2 shows a case where the proximity sensor 2 is installed at the tip of the link 1a or the like. For example, ultrasonic sensors 21a to 21e as an example of the proximity sensor 2 are installed in the vertical direction, the horizontal direction, and the front and rear direction with respect to the link tip having a rectangular parallelepiped housing, and the ultrasonic sensors 21a to 21e are As an example, an operator from a distance of 2 to 3 m to a distance of 20 cm from the link is detected. This detection distance is variable depending on the performance of the proximity sensor 2 installed as described above.

Similarly, the electrostatic capacitance sensor 22 is installed on the entire surface or a part of the link housing, and the electrostatic capacitance sensor 22 detects an operator who contacts the link from, for example, the vicinity 20 cm. The detection distance is variable depending on the performance of the proximity sensor 2 to be installed.
In this specification, the term “proximity sensor 2” is a generic term for the above-described ultrasonic sensors 21a to 21e (may be collectively referred to as “ultrasonic sensor 21”), the capacitance sensor 22, and the like. It is used as. Each proximity sensor 2 is given a sensor ID which is a number for identifying the plurality of proximity sensors 2.

  Moreover, the shape of each link 1a-1f may be a columnar shape or a curved shape, and the above-described installation position and installation direction in the proximity sensor 2 are relative, and are defined in the specifications of the robot arm 1. As long as it can be set in the arm control unit 5 at any position.

  The detection distance of the proximity sensor 2 installed on the robot arm 1 is variable depending on the moving speed of the robot arm 1, but may be a fixed length. By setting the detection distance of the proximity sensor 2 to the maximum detection distance based on the link length in the robot arm 1, for example, the detection distance greater than or equal to the link length, an operator existing within the reach of the link is detected. Thus, the number of proximity sensors 2 installed on the robot arm 1 can be reduced. For example, even if a link has a large link length and a wide operating range, the proximity sensor 2 having a detection distance equal to or longer than the link length can be used to reduce the wide operating range to at least one proximity sensor 2. And the number of installed proximity sensors 2 can be reduced.

  By configuring the plurality of proximity sensors 2 as described above, the proximity sensor 2 that performs different distance detection is used to detect and complement the proximity distance, which is a dead zone of one proximity sensor, with the other proximity sensor. The dead zone of the operator can be eliminated.

  The environment sensor 3 monitors the entire work space of the robot arm 1 and detects the entry / exit of the worker to / from the work space of the robot arm 1. The environment sensor 3 detects an operator's identification, a moving direction, a moving speed, etc. from an acquired image as a change in work space using area sensors, such as a surveillance camera and a laser scanner. Although one to a plurality of environmental sensors 3 are installed at positions where the work space can be monitored according to the work environment, it is not necessary to install them at all. FIG. 1 shows a case where two environmental sensors 3 are installed.

  When a plurality of environment sensors 3 are installed, the robot arm 1 and the worker's work space can be generated as a stereoscopic image. Therefore, the three-dimensional positions of the worker and the robot arm 1 in the work space can be specified, and the avoidance operation of the worker of the robot arm 1 can be accurately controlled.

The sensor processing unit 4 determines the position of the worker from the detection information of the distance between the robot arm 1 and the worker obtained from the proximity sensor 2 and the entry / exit information of the worker in the work space obtained from the environment sensor 3. The position information of the operator is identified and the arm control unit 5 is notified. The distance detection information by the proximity sensor 2 is selected by the arm control unit 5 as necessary, as will be described later.
Further, the output signal of the environment sensor 3 may be directly supplied to the arm controller 5. The sensor processing unit 4 may be integrated with the arm control unit 5 as a function of the arm control unit 5.

The arm control unit 5 controls the work operation of the links 1 a to 1 f including the joints, which are work arms of the robot arm 1. That is, when the operator approaches the robot arm 1, the arm control unit 5 moves based on the operation procedure of the robot arm 1 at that time, and the movement speed that would interfere with the operator and cause danger. One or a plurality of the proximity sensors 2 arranged in the direction are selected and notified to the sensor processing unit 4.
The sensor processing unit 4 notified of the selection information of the proximity sensor 2 controls the proximity sensor 2 corresponding to the selection information, acquires distance information with respect to the worker from the controlled proximity sensor 2 and notifies the arm control unit 5 of the information. To do. The arm control unit 5 analyzes the interference between the robot arm 1 and the worker from the obtained distance information to the worker, and changes the working state or operating state of the robot arm 1.
Here, the “work procedure of the robot arm 1” information used by the arm control unit 5 to select the proximity sensor 2 uses the record information input to the arm control unit 5 in accordance with a predetermined work procedure.

  FIG. 3 shows a system block configuration of hardware and software to which the present embodiment is applied, and shows a robot arm 1, an arm control unit 5 corresponding to a robot controller, and a sensor processing unit 4. . The arm control unit 5 includes a robot control module 51 that performs operation control and work procedure control of the robot arm 1, a human detection module 43, and a human recognition module 44. The sensor processing unit 4 includes a sensor ECU (Electric Control Unit) 41 that performs signal processing on the proximity sensor 2 and the environment sensor 3, and a communication I / F (interface) 42. An ultrasonic sensor 21 and a capacitance sensor 22 as the proximity sensor 2 are connected to the sensor ECU 41. As described above, the proximity sensor 2 may be a sensor of another detection method. In addition, the human detection module 43 and the human recognition module 44 may be included in the sensor processing unit 4.

  Information from the proximity sensor 2 is supplied to the sensor ECU 41. The ultrasonic sensor 21 of the proximity sensor 2 performs time measurement using ultrasonic echoes from a distant place to a nearby worker, and the sensor ECU 41 converts the distance information into an arm control unit via the communication I / F 42. 5 supplies the distance information. Further, the capacitance sensor 22 of the proximity sensors 2 outputs distance information of about 20 cm or less as described above. On the other hand, when the operator approaches the robot arm 1 and the robot arm 1 is stopped, the electrostatic capacity sensor 22 intentionally contacts the robot arm 1 again after the stop so that the robot arm 1 A man-machine interface can be used as a work start switch. Here, when the capacitance sensor 22 is configured as a man-machine interface, the sensor processing unit 4 or the arm control unit 5 has a function of restarting the robot arm 1.

  As described above, when the proximity sensor 2 is used as the man-machine interface configuration, the stopped robot arm 1 can be reactivated, and the labor for restarting the arm control unit 5 can be omitted. Can be improved.

  The arm control unit 5 corresponding to the robot controller includes software and hardware that constitute the robot control module 51, the human recognition module 44, the human detection module 43, and the like. The conventional robot controller performs only the robot control. However, by adding the detection signal processing operation by the human recognition module 44 and the human detection module 43, the robot arm 1 and the human being in the collaborative robot system 101 are added. Enables collaborative work with. The added human recognition module 44 and human detection module 43 may be integrated with their functions with the robot control module 51, or may be a controller configured with hardware separate from the robot controller.

  The human recognition module 44 is a functional part having software and hardware that processes an image acquired by a monitoring camera that is an example of the environmental sensor 3 and detects the presence / absence, position, movement, etc. of the worker in a predetermined work space. It is. The human recognition module 44 may be integrated with the environment sensor 3 (monitoring camera).

The human detection module 43 selects the proximity sensor 2 installed at a location calculated based on predetermined position coordinates at which the robot arm 1 operates, that is, the work procedure of the robot arm 1, and the selected proximity sensor 2 The position information of the worker obtained from is output.
The function of the human detection module 43 is as follows:
・ Enter the world coordinates (X, Y, Z) of the tip of the robot arm 1 ・ Calculate the speed vector of the tip of the robot arm 1 from the world coordinates (X, Y, Z) ・ Select and instruct the sensor ID to be measured from the speed vector・ Reading the distance information of the proximity object (worker) from the proximity sensor with the selected sensor ID ・ Calculating the speed of the proximity object (worker) from the sensor distance information ・ Recording the time stamp determined by the distance information and the speed information -Output the measured distance information and time stamp for the input world coordinates (X, Y, Z)-Logging of proximity sensor data-Self-diagnosis, etc.
The world coordinates are absolute position coordinates assigned to the work space of the robot arm 1 and have a correlation with the position coordinates of the actual work space. However, relative coordinates obtained by aligning the origin of the work space of the robot arm 1 and the actual work space as the origin may be used.

Of the above-described functions in the human detection module 43, the “calculation of the velocity vector at the tip of the robot arm 1” function will be described in detail below. Here, the “tip of the robot arm 1” corresponds to, for example, the tip of the “link 1f” shown in FIG. 1 or the tip of each of the links 1a to 1f.
Assuming that the world coordinates of the tip of the robot arm 1 are (X, Y, Z), the velocity vector calculation of the tip of the robot arm 1 is as follows. The time difference is obtained from the time change of the world coordinates, and the velocity vector at the tip of the robot arm 1 is calculated. It is assumed that the time difference is an update cycle Δt (ms unit) of the proximity sensor 2 and can be set and adjusted.

The time is t and the world coordinates of t + Δt are
If WP (t) = (X (t), Y (t), Z (t)), WP (t + Δt) = (X (t + Δt), Y (t + Δt), Z (t + Δt))
The velocity vector ΔV [m / s] is
ΔV = (dX / dt, dY / dt, dZ / dt) = (ΔVx, ΔVy, ΔVz) = (WP (t + Δt) −WP (t)) / Δt
It becomes.

The world coordinate movement direction Δθ [° / s]
Δθxy = (X (t) * Y (t) + X (t + Δt) * Y (t + Δt)) / (√ (X (t) * X (t + Δt)) * √ (Y (t) * Y (t + Δt)))
Δθyz = (Y (t) * Z (t) + Y (t + Δt) * Z (t + Δt)) / (√ (Y (t) * Y (t + Δt)) * √ (Z (t) * Z (t + Δt)))
Δθzx = (Z (t) * X (t) + Z (t + Δt) * X (t + Δt)) / (√ (Z (t) * Z (t + Δt)) * √ (X (t) * X (t + Δt)))
It becomes.

  With respect to the tip of the robot arm 1, six fixed axes of ± X, ± Y, and ± Z are given on the world coordinate axis shown in FIG. 4, and the proximity sensor 2 shown in FIG. A sensor ID is assigned to the coordinate position of the proximity sensor 2. From the calculated ΔV maximum value of the velocity vector and the moving directions Δθxy, Δθyz, and Δθzx, one of ± X, ± Y, and ± Z is selected, and the sensor ID of the proximity sensor 2 existing in the selected direction is determined. At this time, the moving directions Δθxy, Δθyz, and Δθzx are set within ± 45 ° and can be adjusted.

Further, the sensor ECU 41 obtains a time difference from the time change of the distance information obtained by the sensor ECU 41, and calculates the speed of the proximity object (worker). The time difference is assumed to be a sensor update cycle Δt (in ms units) and can be set and adjusted.
The distance information of time t, t + Δt of the unique sensor ID,
When D (t) [cm] and D (t + Δt) [cm],
The velocity vector ΔV is
ΔV [cm / ms] = dD / dt = (D (t + Δt) −D (t)) / Δt
It becomes.

The ultrasonic sensor 21 starts distance measurement by output of a specified time (adjustable) from the sensor ECU 41. The sensor ECU 41 measures the time from the start of reading to the end of reading after the elapse of a certain mask time (adjustable) from the time of the input trigger, and sets it as the ultrasonic propagation time T [us]. The sensor ECU 41 includes a temperature sensor. When the ambient temperature temp [° C.] of the sensor ECU 41 obtained from the temperature sensor is assumed, the measurement distance D [cm]
D = (331.5 + 0.6 * temp) / 10000 * T
(Example. (331.5 + 0.6 * 25 [° C.] / 10000 * 1000 [us] = 34.65 [cm])
It becomes.

  The electrostatic capacitance sensor 22 starts proximity detection output by output from the sensor ECU 41 for a specified time (adjustable). The sensor ECU 41 samples the proximity detection output several times between the start of reading and the end of reading after the elapse of a certain mask time (adjustable) from the time of the input trigger, and sets the logic of proximity: H, proximity: L . In this logic, H and L may be reversed.

  When the sensor ECU 41 is configured separately from the arm control unit 5, the sensor ECU 41 shares sensor information with the robot control module 51 and the human detection module 43 through wired communication or wireless communication. Information exchange among the robot control module 51, the human detection module 43, and the sensor ECU 41 is performed in the shared memory 53. The shared memory 53 has two memories, each of which performs an operation of writing and reading the other. Similarly, the person recognition module 44 may use the shared memory 53. Even when the sensor ECU 41 is configured integrally with the arm control unit 5, information may be shared in the same manner.

  Providing the shared memory 53 makes it possible to share information between the proximity sensor 2 and the arm control unit 5 even when access between the proximity sensor 2 and the arm control unit 5 is not synchronized.

FIG. 5 shows an information exchange sequence among the robot control module 51, the human detection module 43, and the sensor ECU 41.
The current position of the tip of the robot arm 1 is written from the robot control module 51 to the shared memory 53 with the human detection module 43, and the human detection module 43 designates the sensor ID of the proximity sensor 2 to be operated. For the designation of the sensor ID, all of the plurality of proximity sensors 2 may be designated, or only a part (one or a plurality) may be designated.

  The human detection module 43 records the current position of the tip of the robot arm 1 written in the shared memory 53. The human detection module 43 has an operation counter and records a count value in which the current position of the tip of the robot arm 1 is written or a count value in which the current position of the tip of the robot arm 1 is recorded. If this count value is incremented or decremented, it indicates that the human detection module 43 is operating, and can be used for detecting an abnormal operation of the human detection module 43.

  Next, the human detection module 43 outputs an operation instruction to the proximity sensor 2 having the sensor ID designated for the sensor ECU 41. The sensor ECU 41 notifies the distance information with respect to the worker sent by the proximity sensor 2 corresponding to the sensor ID designated by the human detection module 43. The sensor ECU 41 also has an operation counter, and records the count value informing the distance information. If this count value is incremented or decremented, it indicates that the sensor ECU 41 is operating, and can be used for detecting an abnormal operation of the sensor ECU 41. At this time, the human detection module 43 calculates the speed from the difference between the current distance information and the distance information output last time.

Furthermore, the human detection module 43 writes each information such as distance and speed notified from the sensor ECU 41 in the shared memory 53.
The robot control module 51 determines the approach or withdrawal of the worker from the information in the shared memory 53, corrects the position of the robot arm 1, or stops the operation of the robot arm 1.

  According to the configuration of the collaborative robot system 101 described above, it is possible to quickly detect the approaching and leaving of the operator with respect to the robot arm 1. Therefore, it is possible to prevent the worker from approaching the robot arm 1 and coming into contact with the robot arm 1 that is working, and to ensure both the safety of the worker and the high-speed operation of the robot arm 1.

Next, FIG. 6 shows a series of operation flows when the collaborative robot system 101 detects an operator.
The arm control unit 5 analyzes the position, operation procedure, operation speed, and operation acceleration of the entire robot arm 1 (step 10b). The operation procedure of the robot arm 1 and the proximity sensor 2 that is optimal for worker detection Are sequentially associated (10c).

When the operation procedure of the robot arm 1 is started (10d), the arm controller 5 selects an optimum proximity sensor from the plurality of proximity sensors 2 in order to quickly detect the worker (10e), and from the selected proximity sensor 2 The distance information which is the proximity information of the worker is collected (10f).
The arm controller 5 (specifically, the human detection module 43) calculates the position, speed, acceleration, etc. of the worker from the collected distance information (10g), and the worker is linked to the link where the selected proximity sensor 2 is installed. (10h).

It is determined whether the operator is approaching the link where the selected proximity sensor 2 is installed (10i).
When the worker is approaching the robot arm 1, the operation of the approaching link (arm) is changed. This change in the link operation corresponds to a change in the link operation speed, a stop of the link operation, avoidance of the link operator, a return of the robot arm 1 to the work start position, and the like.

  On the other hand, when the worker is not approaching the robot arm 1, that is, the worker is separated from the robot arm 1 by a predetermined distance or more, or the robot arm 1 is stationary at the current position, or the worker is a robot. When the user leaves the arm 1, the operation of the robot arm 1 is not changed as the current state is maintained, and a series of work operations are continued.

A supplementary explanation will be given for the determination (10i) of whether or not the worker is approaching the link where the selected proximity sensor 2 is installed.
The robot control module 51 analyzes a specified series of work procedures and calculates a motion vector from the current world coordinates of the tip of the robot arm 1 and the world coordinates after t seconds. From the obtained motion vector of the tip of the robot arm 1, the robot control module 51 extracts the proximity sensor 2 in the link in the moving direction, and gives a detection instruction for the proximity sensor 2 to the human detection module 43.
The human detection module 43 acquires the instructed distance and speed detected by the proximity sensor 2. The robot control module 51 detects the approach of the worker to the link in the moving direction using the acquired distance and speed to the worker as the target object, and whether or not the robot arm 1 and the worker interfere with each other. That is, it is determined whether or not the worker is safe.

Whether the robot arm 1 and the worker interfere with each other, that is, whether or not the worker is safe is determined according to the following time condition and distance condition. In the determination, either a time condition or a distance condition may be used. here,
Worker speed: V1
Robot arm 1 speed: V2
Set distance to worker's safety area: L1 [m]
Set distance of safety area in robot arm 1: L2 [m]
Then, the judgment condition for whether or not it is safe is as follows.

The time condition that the robot arm 1 may continue working is as follows:
Time to reach the set distance in the safety area when the operator moves at a constant speed:
Tc1 = L1 / V1 [sec]
Time until the robot arm 1 reaches the set distance in the safety area:
Tc2 = L2 / V2 [sec]
When
Judgment conditions for safety: Tc1 ≦ Tc2 or Tc1 <Tc2
It becomes.

The distance condition that the robot arm 1 may continue working is as follows:
Acceleration when the worker moves: α [m / s2]
Minimum time for the robot arm 1 to reach the set distance in the safety area:
Tc2min = L2 / V2 [sec]
Maximum distance that an operator can accelerate and enter the safe area:
Lmax = α / 2 × Tc2min ^ 2
When
Judgment condition: L1 ≦ Lmax or L1 <Lmax
It becomes.
By determining the condition, it is possible to avoid the interference between the operator and the robot arm 1.

  As described above, according to the collaborative robot system 101, the safety of the worker is enhanced, the safety distance between the robot arm 1 and the worker is secured, and the speed reduction of the robot arm 1 caused by the movement or position of the worker is achieved. It is possible to avoid operation stop and the like. Thereby, the working efficiency of the robot arm 1 and the operator can be improved.

Embodiment 2. FIG.
FIG. 7 shows a schematic configuration of the cooperative robot system 102 according to the second embodiment. In the collaborative robot system 102 according to the second embodiment, a wireless position detection unit 9 is provided instead of the environment sensor 3 according to the first embodiment. The wireless position detection unit 9 includes an antenna 7 that transmits and receives radio waves, and one or a plurality of antennas 7 are arranged to cover the robot arm 1 and the worker's work space wirelessly. The worker wears a wireless tag 8 that can be detected by the wireless position detector 9.
Other configurations are the same as the configuration of the cooperative robot system 101 in the first embodiment. Therefore, in the following, this difference will be described in particular, and description of the same component will be omitted.

The wireless position detection unit 9 detects two-dimensional or three-dimensional position coordinates of the wireless tag 8 carried by the worker. The radio frequency band used for the radio position detection unit 9 is an LF band (125 kHz, 21 kHz, etc.), and transmits the radio frequency of the LF band.
Next, the radio tag 8 receives the radio frequency of the LF band transmitted from the radio position detector 9, and uses a radio frequency band different from the radio frequency of the LF band such as VHF or UHF, and uses the radio frequency of the LF band. Send the received strength.
Next, the wireless position detection unit 9 receives the reception strength of the radio frequency in the LF band transmitted from the wireless tag 8. These operations are repeated for the number of installed antennas 7.

  The electric field strength of the radio frequency in the LF band from the wireless tag 8 has a distance attenuation characteristic as shown in FIG. That is, the electric field strength is such that the distance attenuation characteristic is linear when the wireless tag 8 and the wireless position detection unit 9 are at a short distance, and the distance attenuation decreases as the distance increases, and becomes the cube of the distance from the antenna 7. Shows a tendency to decay proportionally. Further, the radio frequency of the LF band is less deteriorated in radio propagation due to shielding of the robot arm 1 or its peripheral devices and equipment.

  When three antennas 7 are installed, the first antenna 7-1 (FIG. 9A), the second antenna 7-2 (FIG. 9B), and the third antenna 7-3 (FIG. 9C), each antenna 7 and the operator Identifies the distance R1 from the received electric field strength V1 of the first antenna 7-1 and similarly identifies the distance R1 from the received electric field strength V1 of the second antenna 7-2. Then, the distance R1 is specified from the received electric field strength V1 of the third antenna 7-3.

  Next, as shown in FIG. 10, the position of the first antenna 7-1 is x1, y1, and the position of the wireless tag 8 is on a circle of distance R1. Similarly, the position of the wireless tag 8 exists on a circle with a distance R2 where the position of the second antenna 7-2 is x2 and y2, and the position of the wireless tag 8 is the position of the third antenna 7-3 as x3 and y3. Exists on a circle of distance R3. Therefore, the positions x0 and y0 of the wireless tag 8 exist at the intersections of the above-described three circles, and the wireless position detection unit 9 can estimate the position of the wireless tag 8.

Therefore, the arm control unit 5 calculates the presence / absence of the worker in the work space of the robot arm 1 and the position of the worker from the robot arm 1 based on the worker's position obtained from the wireless position detection unit 9. .
In the configuration of the collaborative robot system 102, the proximity sensor 2 is selected from the worker position and the work procedure of the robot arm 1, the approaching or leaving of the worker is detected, the safety of the worker is ensured, and the worker The work efficiency of the robot arm 1 is prevented from being lowered due to the approach of.

  When a plurality of antennas 7 are installed, a monitoring image of the work space of the robot arm 1 can be three-dimensionally acquired, and the three-dimensional position in the work space of the worker can be specified. Therefore, since the positions of the operator and the robot arm 1 can be detected with high accuracy, the avoidance operation of the operator of the robot arm 1 can be accurately controlled.

Further, the wireless tag 8 may be assigned a type ID that identifies the worker. The type ID is, for example, the skill level of the worker, the years of service, gender, maintenance person, general person, etc., and the combination of the safety distance between the robot arm 1 and the worker and the control operation speed according to the type ID. Can be changed.
Thereby, at the same time as detecting the position of the wireless tag 8 worn by the worker, the operator can be specified by the type of the wireless tag 8 worn by the worker and the control operation speed of the robot arm 1 can be changed. Therefore, it is possible to efficiently improve the work efficiency of the robot arm 1 by reflecting the safety ensuring according to the type of the worker and the approaching degree of the worker engaged in the work.

In addition, it can be made to show each effect which each above-mentioned embodiment combines suitably.
Although the present invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.
In addition, Japanese Patent Application No. 1 filed on Jan. 13, 2017 was submitted. The entire contents of the specification, drawings, claims, and abstract of Japanese Patent Application No. 2017-3887 are incorporated herein by reference.

1 robot arm, 2 proximity sensor, 3 environmental sensor, 4 sensor processing unit,
5 arm control unit, 7 antenna, 8 radio tag, 9 radio position detection unit,
101, 102 Collaborative robot system.

Claims (11)

In a collaborative robot system that includes a robot arm and allows an operator to approach the robot arm,
A plurality of proximity sensors attached to the robot arm for detecting the approach of the worker to the robot arm;
An arm control unit that selects a proximity sensor used for worker detection from the plurality of proximity sensors according to a work procedure of the robot arm;
A collaborative robot system characterized by comprising:   Based on the robot arm work procedure, select one or more of the proximity sensors from the proximity sensors that are arranged in the direction of the moving speed that would interfere with the operator due to the movement of the robot arm. The collaborative robot system according to claim 1.   The cooperative robot system according to claim 1, wherein the proximity sensor has a plurality of types of configurations having different detection distances and capable of complementing distances.   The collaborative robot system according to any one of claims 1 to 3, wherein the proximity sensor is disposed at a distal end portion of a link constituting the robot arm and has a detection range equal to or longer than a length of the link. . An environmental sensor for detecting the entry / exit of the worker into the operation range of the robot arm
5. The collaborative robot system according to claim 1, wherein the arm control unit includes a human recognition module that obtains the position of an operator based on information obtained from the proximity sensor and the environmental sensor.   The cooperative robot system according to claim 5, wherein a plurality of the environmental sensors are provided, and the arm control unit has a function of generating a stereoscopic image of an operation range of the robot arm. The worker has a wireless tag,
A wireless position detector for detecting entry and exit of the wireless tag within the operating range of the robot arm;
The said arm control part has a person recognition module which performs acquisition of a worker position and determination of a worker type with the information obtained from the said proximity sensor and the said wireless position detection part. The collaborative robot system according to the item.   The arm control unit stops the operation of the robot arm according to the worker position obtained by the person recognition module, and restarts the robot arm by the operator's contact with the proximity sensor in the stopped robot arm. The collaborative robot system according to any one of claims 5 to 7, which has a function.   The collaborative robot system according to claim 5, further comprising a shared memory accessible by the human recognition module and the arm control unit. A control method of a collaborative robot system comprising a robot arm to which a plurality of proximity sensors for detecting the approach of an operator are attached, the operator being able to approach the robot arm,
A proximity sensor used for worker detection is selected from the plurality of proximity sensors according to the work procedure of the robot arm.
A control method characterized by that.   The control method according to claim 10, wherein a work state or an operation state of the robot arm is changed in accordance with worker position information obtained from the selected proximity sensor.

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