JP5212754B2 - Work support system - Google Patents

Description

  The present invention relates to an industrial robot system at a manufacturing site, and more particularly to a work support system that assists a worker who performs an assembly work.

  Industrial robots play an important role in efficient production with stable quality at manufacturing sites. The range of use has continued to expand, including spot welding and painting on automobile bodies, assembling parts on electronic circuit boards, and boxing of products.

  However, there are still many processes that have not been automated by industrial robots. For example, the assembly process of automobiles and the assembly process of electrical products are still performed manually because they are difficult to replace with industrial robots. In recent years, the aging of society and the declining birthrate are rapidly progressing worldwide, and there is concern about a decrease in the working population. Under such circumstances, the problem of securing the labor force is inevitable even at the manufacturing site, and further automation is required in the assembly process.

  In the assembly process of automobiles, workers need to go back and forth between the place of installation of parts and tools near the work place and the work place to select parts and take out tools. Time and effort.

  Patent Document 1 discloses a work support robot that performs work support in an automobile assembly process to reduce the burden on an operator and improve work efficiency.

  In an automobile assembly process that is difficult to be completely automated by a robot, the work support robot of Patent Document 1 transports parts and tools to the operator's hand by a robot arm or the like. Even when the worker does not operate the robot, the work support robot always recognizes the state of the worker and presents necessary parts and tools to the worker. Thereby, the work etc. which take the tool etc. which accompany an original assembly work etc. can be reduced, a worker's burden can be reduced, and work efficiency can be improved. Further, when the worker's work does not correspond to the operation of the robot, it is found that the worker is not performing the work according to the work process chart, and the work mistake can be detected.

  Since the work support robot conveys parts and tools to the operator's hand, it operates in the same work space as the operator. In addition, the work support robot estimates the work progress from the movement of the worker and operates according to the situation, so that the operation of the worker is not required. Therefore, since the worker does not always watch the movement of the work support robot during work, even if the assembly work support robot is operating normally, it can come into contact with the worker due to excessive proximity. There is sex.

  As research on safety measures for assembly work support robots that operate in the same space as humans, the development of robots that support work while performing risk assessment for safety has been conducted. As an assembly work support partner robot in an automobile assembly process, Non-Patent Document 1 cooperates with an operator with an instrument panel-mounted auxiliary machine, Non-Patent Document 2 with a window-mounted auxiliary machine, and Non-Patent Document 3 with a low output drive. A spare tire automatic robot is disclosed.

International Publication No. 2010/134603

Hitoshi Konosu, Isamu Araki, Yoshi Yamada, “Practical Use of Skill Assist for Automobile Assembly Work Support Device”, Journal of the Robotics Society of Japan, vol. 22, no. 4, pp. 86-92, 2004. Murayama Hideyuki, Takei Naoyuki, Matsumoto Kuniho, Konosu Hitoshi, Fujimoto Hideo, “Automotive Assembly Line Window Mounting Robot”, Journal of the Robotics Society of Japan, vol. 28, no. 5, pp. 624-630, 2010. Hideyuki Murayama, Hirotoshi Fujiwara, Yoshio Nakano, Kenji Ishii, Naoyuki Takei, Toshiro Morita, Yuichi Hobayashi, Hideo Fujimoto, “Practical application of a 25kg portable energy-saving robot with 80W motor”, Proceedings of the 28th Annual Conference of the Robotics Society of Japan Shu, RSJ2010AC3J1-1, 2010.

  Since normal industrial robots operate while being surrounded by a safety fence, if an operator enters the robot's operating area and there is a possibility of interference, a safety device such as an alarm device or emergency stop of the robot is activated. To do. Furthermore, since the work support robots disclosed in Non-Patent Documents 1 to 3 mainly operate based on the operator's operating force, the operator can operate the robot while recognizing the robot motion trajectory.

  On the other hand, even if the robot does not require the operator's operation, the operator's intention is estimated, the situation of the work is grasped and the operation is performed, the work support robot is operated by supplying parts and tools. When approaching, the robot may come into contact with the operator even though the robot is operating normally.

  However, in an environment where a robot and a human work together, the robot's operating speed is fast, close enough to contact a human, and a safe operating method of the robot in a situation where the human hardly sees the robot. It has not been discussed so far.

  Accordingly, an object of the present invention is to provide a work support system that detects an approach with an operator, prevents a collision, and prevents an accident even in the event of a collision.

In order to achieve the above object, a work support system of the present invention includes an arm configured by connecting a plurality of arm portions via a connecting portion, and a transport mechanism for transporting one or both of a tool and a part, and A motor and a torque limiter mounted on the motor, a drive unit that operates the transport mechanism, a detection unit that detects the worker in the region of the movement direction of the transport mechanism, and when the worker is detected by the detection unit , An emergency operation generator that controls the movement of the transport mechanism by driving the motor with a torque smaller than the torque at which the torque limiter operates . When the detection unit detects the operator, the emergency motion generation unit obtains, as a command value, a torque value that does not exceed the operating limit value of the torque limiter from the arm motion model, and calculates the angle, angular velocity, and command of the arm unit in operation. The conveyance mechanism is stopped without operating the torque limiter by calculating an angular velocity as a target value of the arm portion from the value and inputting it to the motor .

The work support system of the present invention, preferably, the detection unit is dispersed belong to any group system, a plurality of sensors spaced on each side of the arm portion, the signals from a plurality of sensors And a processing unit for each group system to be processed, and when the processing unit of at least one group system receives an output from the sensor, the emergency motion generation unit regulates the movement of the transport mechanism. Furthermore, the processing unit for each group system includes a comparison circuit that receives an input of a voltage signal output from a sensor belonging to the group system, and each comparison circuit compares the input voltage signal with a reference voltage determined by a detection position. Then, the emergency motion generation unit performs braking control on the arm in accordance with the output from each comparison circuit.
In the above configuration, the detection distance of each sensor is set according to the braking distance at the set position of each sensor determined based on the motion state of the transport mechanism.

  According to the present invention, it is possible to prevent the moving transport mechanism from coming into contact with the worker even when the worker moves unexpectedly. Also, in the event of a collision due to a runaway motor, the pressing force is prevented. Can be reduced and accidents can be prevented. Even when a collision with the worker occurs because the motor continues to rotate due to a system runaway or the like, the movement of the transport mechanism is freed by operating the torque limiter, and the pressing force against the worker can be reduced. However, when the torque limiter is installed, if the transport mechanism is suddenly stopped, the torque limiter is actuated by the inertia force at the time of deceleration, and the transport mechanism moves freely, and the transport mechanism comes into contact with the operator. According to the present invention, since the motor is brake-controlled with a torque smaller than the torque at which the torque limiter operates when the detection unit detects the operator, the transport mechanism can be stopped without operating the torque limiter. Further, when the transport mechanism includes an exterior made of a cushioning material, even if the transport mechanism comes into contact with the operator after the torque limiter is activated, the impact force on the worker can be reduced.

1 is a perspective view showing a work support system according to an embodiment of the present invention. It is a block diagram of a control device concerning an embodiment of the present invention. It is a figure for demonstrating the proximity detection part which concerns on embodiment of this invention. It is sectional drawing of the 1st arm part which concerns on embodiment of this invention. It is a figure for demonstrating the proximity detection part which concerns on embodiment of this invention. It is a block diagram of the process part which concerns on embodiment of this invention. It is a figure which shows the exercise | movement model of the arm which concerns on embodiment of this invention. It is a figure which shows the control law of the emergency operation | movement production | generation part which concerns on embodiment of this invention. It is a figure which shows the relationship between the hand speed which concerns on embodiment of this invention, and the error of braking distance. It is a figure for demonstrating the precondition of the experiment example of this invention.

1. Outline In a work support system according to an embodiment of the present invention, in an assembly work performed while a worker moves within a certain range, such as an automobile assembly process, the necessary parts and tools are handed to the worker when needed by the worker. It is characterized by being transported to.
Specifically, the work support system acquires the position information of the worker, estimates the work currently being performed by the worker and the progress thereof from the position information and the probabilistic work model of the worker. Based on the estimated information, an appropriate transfer position and transfer time of a part and / or tool to be used for the next operation are determined, and a transfer mechanism for transferring the part and / or tool to the hand is controlled.

  Furthermore, in the work support system, since the movement of the transport mechanism does not depend on the operator's operation, the transport mechanism and the worker may collide when the worker moves to a place off the work position on the way. Therefore, when the worker approaches the transport mechanism, the movement of the transport mechanism is restricted and the transport mechanism is prevented from coming into contact with the worker.

2. Configuration FIG. 1 is a perspective view showing a work support system 1 according to an embodiment of the present invention.
The work support system 1 includes a base frame 10, a transport mechanism 20 that transports parts and / or tools to the hand of an operator, a drive unit 30 that moves the transport mechanism 20, and a measurement unit 40 that measures the motion of the worker. And a control device 50 that controls the operation of the transport mechanism 20. In addition, the display of the measurement part 40 is abbreviate | omitted in FIG.

  In the work support system 1 of the present embodiment, the arm 20 </ b> A is used as the transport mechanism 20. The arm 20 </ b> A is rotatably attached to the base frame 10. The arm 20 </ b> A has a base end portion rotatably connected to the base frame 10 and a base end portion rotatably connected to a distal end portion of the first arm portion 21 via a connecting portion 23. The second arm portion 22 is provided, and a holding portion 24 provided at the distal end portion of the second arm portion 22. The first arm portion 21 and the second arm portion 22 include frames 21A and 22A that extend straight, and these frames 21A and 22A are arranged to extend horizontally. As shown in FIG. 1, the first arm part 21 and the second arm part 22 are arranged so that the second arm part 22 is shifted upward from the height of the first arm part 21 so as not to overlap in the horizontal direction. It is installed. The connecting portion 23 includes a bearing portion 23A that is fixed to the distal end portion of the first arm portion 21, and a shaft portion 23B that is received by the bearing portion 23A and is fixed to the proximal end portion of the second arm 22. . The shaft portion 23 </ b> B functions as a rotation shaft for the second arm portion 22 to rotate with respect to the first arm portion 21.

  The drive unit 30 includes a first motor 31 that rotates the first arm unit 21 and a second motor 32 that rotates the second arm unit 22. Timing pulleys 33 and 34 are respectively attached to the output shaft 31A of the first motor 31 and the rotating shaft 21B at the base end of the first arm portion 21, and these timing pulleys 33 and 34 are not shown. Connected with a belt. The rotation of the first motor 31 is transmitted to the first arm portion 21 via the belt and the timing pulleys 33 and 34, and the first arm portion 21 rotates.

  Timing pulleys 35 and 36 are respectively attached to the output shaft of the second motor 32 and the rotation shaft 23B of the base end portion of the second arm portion 22, and these timing pulleys 35 and 36 are belts not shown. It is connected. The output shaft of the second motor 32 is configured coaxially with the rotation shaft 21 </ b> B of the base end portion of the first arm portion 21.

  Further, a torque limiter (not shown) is mounted on each of the output shafts 31A and 21B of the first motor 31 and the second motor 32. When an overload occurs in the first arm portion 21 and the second arm portion 22, the torque limiter functions, and the first arm portion 21 and the second arm portion 22 are caused by the outputs of the first motor 31 and the second motor 32. Can rotate freely. For this reason, it is possible to avoid pressing the arm against the operator even when the motor becomes uncontrollable for some reason and continues to rotate.

  The measuring unit 40 includes a sensor group for measuring the operation of the operator such as a camera or a distance measuring sensor. In the present embodiment, a laser range sensor (LRF: Laser Range Finder) is used. Laser range sensors irradiate laser light, measure laser light reflected by various things such as installation objects, moving workers, and vehicle bodies, and output distance data to the target two-dimensionally To do.

  As shown in FIG. 2, the control device 50 includes a support operation control unit 60 and an emergency operation control unit 70.

  The support operation control unit 60 drives and controls the arm 20 </ b> A in order to convey parts and / or tools to the operator. The support operation control unit 60 includes a work model generation unit 61, a work estimation unit 62, and an operation generation unit 63.

  The work model generation unit 61 probabilistically models the worker's movement. The work model generation unit 61 generates a worker motion model from the worker motion data obtained from the measurement unit 40.

  The work estimation unit 62 estimates the progress of work. The work estimation unit 62 includes a work model created by the work model generation unit 61, worker position information obtained by the measurement unit 40, a plurality of work orders stored in the database 64, and work in each work. The work progress is estimated based on the work information such as the position information of the person.

  The motion generation unit 63 transports parts and / or tools to the operator's hand, that is, the operator's work is performed in order to transport the holding unit 24 on which the component and / or tool is placed or gripped to the operator's hand. The movement information of the arm 20A in accordance with the progress is generated. Specifically, the motion generation unit 63 sets the holding unit 24 at a position to be transported in each work based on the work progress estimated by the work estimation unit 62 and the work model generated by the work model generation unit 61. The trajectory of the arm 20A for movement is calculated. The work estimation performed by the work estimation unit 62 includes correction of the arm trajectory. Thereby, the trajectory of the arm 20A is planned by the motion generation unit 63 according to the work progress status estimated by the work estimation unit 62, and the arm 20A is controlled. That is, the arm 20A is controlled in accordance with the progress of the work, and parts and / or tools necessary for the work are transported. As shown in FIG. 2, the trajectory of the arm 20A generated by the motion generation unit 63 is sent to the drive unit 30 via an emergency motion generation unit 72 described later. When an emergency motion generation unit 63, which will be described in detail later, does not perform braking control, the drive unit 30 controls the arm 20 based on a trajectory generated by the motion generation unit 63, specifically, a target motion such as a target angular velocity. .

  The above control device 50 is composed of a computer. The computer functions as a work model generation unit 61, a work estimation unit 62, and an operation generation unit 63 by executing software installed in advance. If the measurement unit 40 is an LRF, the control device 50 also includes a part that processes sensor data obtained from the LRF.

  Note that a plurality of computers may be connected by a LAN, and the operations of the work model generation unit 61, the work estimation unit 62, and the motion generation unit 63 may be distributed by a plurality of personal computers. A computer having a conventionally known configuration can be used, and is stored in a storage device such as a RAM, a ROM, a hard disk, an operation device such as a keyboard and a pointing device, and an instruction from the operation device. A central processing unit (CPU) for processing data and software, a display for displaying processing results, and the like are provided. This computer may be a general-purpose device or a dedicated device.

  The operation generation unit 63 as a computer acquires information on the angles of the first motor 31 and the second motor 32 from a counter board connected by a PCI component (Peripheral Component Interconnect Bus), and sends a motor driver from the D / A board. The first motor 31 and the second motor 32 are controlled via these. Similarly, the initial posture of the arm 20A is set by reading the value of the photomicrosensor with a DIO (Digital I / O) board connected by a PCI bus. Furthermore, production line information such as a vehicle body number and a vehicle type is also input to the computer.

  As described above, the support operation control unit 60 estimates the will of the worker, so that the necessary parts and / or tools can be presented to the worker as expected even if the worker does not explicitly operate. it can. As a result, the work accompanying the original work, that is, the work for the worker himself / her to pick up parts and / or tools can be reduced, and the burden on the worker can be reduced and the work efficiency can be improved.

  Since the movement of the arm 20A by the support operation control unit 60 does not depend on the operator's operation, the arm 20A may collide with the worker when the worker moves to a place off the work position on the way. There is.

  For this reason, the work support system 1 includes an emergency operation control unit 70. As illustrated in FIG. 2, the emergency operation control unit 70 includes a proximity detection unit 71 and an emergency operation generation unit 72.

  The proximity detector 71 detects an operator approaching the arm 20A. Specifically, the proximity detection unit 71 detects the worker when the worker is present in a region extending horizontally from the side surfaces of the first arm unit 21 and the second arm unit 22. Therefore, as shown in FIG. 3, the proximity detection unit 71 includes left and right side surfaces 21D and 21E of the first arm unit 21, left and right side surfaces 22D and 22E of the second arm unit 22, and the first arm unit 21. A plurality of sensors are provided in each of the connecting portion 23 to the second arm portion 22 and the distal end portion of the second arm portion 22. A plurality of sensors are arranged at a distance from each of the side surfaces 21D, 21E, 22D, 22E of the first arm portion 21 and the second arm portion 22, the connecting portion 23, and the distal end portion of the second arm portion 22.

  In the present embodiment, an infrared distance sensor is used as a sensor capable of detecting a distance, for example, an optical position sensor (PSD: Position Sensitive Detector) 75. A symbol α in FIG. 3 represents an infrared image from each optical position sensor 75. In FIG. 1, the display of each optical position sensor 75 is omitted. In addition, the detection distance of the optical position sensor 75 provided in each arm part 21 and 22 is set according to the braking distance corresponding to the speed of each arm part 21 and 22 from time to time.

FIG. 4 is a cross-sectional view of the first arm portion 21. An exterior 210 made of a cushioning material such as sponge or urethane is attached to the frame 21A constituting the arm 20A. The optical position sensor 25 is disposed on the first arm portion 21 so that the optical position sensor 25 faces the arm outward direction from the opening 211 formed in the exterior 210.
In addition, since the infrared distance sensor as the optical position sensor 25 used in this embodiment cannot be accurately detected when the operator approaches too much due to output characteristics, the thickness of the exterior 210 is the minimum detection of the optical position sensor 25. It is set larger than the distance. The exterior 210 can prevent an operator from being so close to the optical position sensor 25 that it cannot be accurately detected. Furthermore, the exterior 210 can relieve the pressing force on the worker even when it collides with the worker in the event of a malfunction due to a failure of the entire work support system or a power failure.

  The proximity detection unit 71 of the present embodiment performs parallel distributed processing. For example, although eight optical position sensors 75 are provided on the left side surface 21D of the first arm portion 21 shown in FIG. 5, the optical position sensors 75 arranged at predetermined intervals in the length direction are arranged from the base end side. The odd number belongs to the first group system 71A, and the even number belongs to the second group system 71B. The output from the optical position sensor 75 belonging to the first group system 71A is sent to the processing unit 76A of the first group system 71A. The result of the processing unit 76A of the first group system 71A is sent to the control device 50.

Processing analog signals of such a large number of sensors individually with an A / D converter in real time is not realistic considering the scale of the measurement system. Therefore, the input signals of a plurality of sensors are collectively processed by an OR circuit, so that even when the number of sensors is large, the number of system input channels can be reduced. In the present embodiment, the reference voltage is applied to the comparator circuit from the D / A board so that the distance for detecting the approach to the worker can be set variably.
Specifically, as shown in FIG. 6, the processing unit 76A of the first group system 71A receives the outputs from the optical position sensors 75 and the outputs from the comparison circuits 77. OR logic circuit 78. The reference voltage of each comparison circuit 77 is determined by the detection distance, and can be set by operating a keyboard or the like connected to the control device 50. A signal detected from any one of the comparison circuits 77 is input to the OR logic circuit 78, whereby it is determined that an operator is in close proximity to the left side surface of the first arm unit 20.

  The output from the optical position sensor 75 belonging to the second group system 71B is sent to the processing unit 76B of the second group system 71B. The processing unit 76B of the second group system 71B is configured similarly to the processing unit 76A of the first group system 71A.

By providing such a distributed sensing system, in the first group system 71A, the output voltages of the four optical position sensors 75 are respectively input to the four comparison circuits 77, and the outputs thereof to one OR logic circuit 78. Is entered. The same applies to the second group system 71B. At this time, if one optical position sensor 75 fails in the first group of systems 71A and no output voltage is generated from the sensor 75, there is no input to one comparison circuit 77. In this case, since the optical position sensors 75 other than the failure location function, the three optical position sensors 75 function in the first group system 71A, and all four optical position sensors 75 function in the second group system 71B. Will be. Next, when one comparison circuit 77 fails in the first group system 71A, the output voltages of the four optical position sensors 75 are processed by the four comparison circuits 77 and input to the OR logic circuit 78, but are not processed. It will be. In this case, all the four optical position sensors 75 function in the second group system 71B. As described above, by arranging the distributed sensing systems in parallel, even if the system on one side breaks down, it is possible to continue to detect obstacles on the other system.
In this way, by connecting another similar sensing system in parallel, even when one sensing system fails, it is possible to detect the approach to the worker.

  Such a distributed sensing system includes a proximity detection unit 71 provided on the right side surface 21E of the first arm unit 21, a proximity detection unit 71 provided on the left and right side surfaces 22D and 22E of the second arm unit 22, and the first arm unit. 21 is also applied to the proximity detector 71 provided at the joint 23 of the second arm 22 and the proximity detector 71 provided at the tip of the second arm 22.

In the present embodiment, as shown in FIG. 3 and the following, a proximity detection unit 71 is provided for each of the six areas A to F near the arm, and each proximity detection unit 71 is configured as a distributed sensing system.
Area A: An area of the sensor detection distance from the tip of the second arm part 22 to 90 degrees to the left and right with the extending direction of the second arm part 22 as the center.
Area B: An area from the left side surface 22D of the second arm portion 22 to the sensor detection distance in the horizontal direction.
Area C: An area from the right side surface 22E of the second arm portion 22 to the sensor detection distance in the horizontal direction.
Area D: An area of the sensor detection distance from the tip of the first arm portion 21 to 90 degrees to the left and right with the extending direction of the first arm portion 21 as the center.
Area E: An area from the left side surface 21D of the first arm portion 21 to the sensor detection distance in the horizontal direction.
Area F: An area from the right side surface 21E of the first arm portion 21 to the sensor detection distance in the horizontal direction.

  As described above, by arranging the optical position sensor 75 in the areas A to F, it is possible to detect the approach to the worker for each part of the arm 20A. The arrangement interval of the optical position sensor 75 is such that the side surfaces 21D, 21E, 22D, and 22E of the arm 20A can detect the operator's torso (including the waist and abdomen regions), and the joint portion 23 of the arm 20A It is set so that the operator's arm can be detected because there is a possibility of pinching. This arrangement interval is desirably set so that the level of the operator's trunk can be detected even when one group of systems does not operate in the distributed sensing system described above.

  When an operator is detected by any of the proximity detection units 71 in these areas A to F, the work support system 1 according to the present embodiment performs braking control on the arm 20A.

  In the present embodiment, the emergency motion generator 72 performs braking control of the arm 20A. When the emergency motion generation unit 72 detects the approach to the worker by the parallel distributed sensing system described above, the emergency motion generation unit 72 prevents the collision with the worker by stopping the arm 20A at the shortest distance. However, when the first motor 31 and the second motor 32 that operate the first arm unit 21 and the second arm unit 22 when the approach to the worker is detected are suddenly stopped, the first arm unit 21 is used. The first arm unit 21 and the second arm unit 22 may become uncontrollable due to the operation of the torque limiter mounted on the first motor 31 and the second motor 32 that operate the first arm unit 22 and the second arm unit 22. There is. In this case, even if the 1st motor 31 and the 2nd motor 32 stop, the 1st arm part 21 and the 2nd arm part 22 will continue to move with an inertial force, and a collision with an operator may occur. In order to prevent this, it is necessary to stop the arm 20A without operating the torque limiter.

  The braking distance necessary for stopping without operating the torque limiter after the work support system 1 receives the stop command is the posture of the arm 20A and the speed at that time when the braking control is started upon receiving the stop command. Depends on.

A motion model of the arm 20A according to this embodiment is shown in FIG. Each parameter, the mass m ₁ of the first arm portion 21, the mass m ₂ of the second arm portion 22, the holding portion 24 and the tool mass m _3, the length l ₁ of the first arm portion 21, the second arm portion 22 length l _2, the centroid distance r ₁ of the first arm portion 21, the center of gravity distance r ₂ of the second arm portion 22, the moment of inertia I ₁ of the first arm portion 21, the moment of inertia I ₂ of the second arm portion 22, The first axial torque T ₁ around the base end side axis of the first arm portion 21 and the second axial torque T ₂ around the base end side axis of the second arm portion 22 were used. The equation of motion of the arm 20A of the work support system 1 is as follows. Expression (1) represents the first arm portion 21, and Expression (2) represents the second arm portion 22.

  The control law of the block diagram shown in FIG. 8 is used for the braking control used in the emergency motion generation unit 72 according to the present embodiment. In order to obtain the stop trajectory using this control law, the following equations (3) and (4) obtained by solving the motion equation of the robot shown in the above equation with respect to acceleration are used. Equation (3) represents the first arm portion 21 and Equation (4) represents the second arm portion 22.

Therefore, the emergency motion generation unit 72 uses the above formulas (3) and (4) to stop the first arm unit 21 and the second arm unit 22 without operating the torque limiter, so that the torques T ₁ , T Command the torque that does not exceed the limit value at which the torque limiter is activated in ₂ . Since the limit value of the torque limiter is, for example, 80 [Nm], the time transition of the torque whose upper limit is a value of 80 [Nm] or less is substituted for the torques T ₁ and T ₂ . The emergency motion generation unit 72 inputs the torque command value from the time when the operator is detected until the arm 20A stops, for example, to the target torque value T _des in FIG. 8 by step input. After substituting the torque command value, the angle θ _cur of the operating robot, and the angular velocity into the equation of motion of FIG. 8, a target angular velocity that is the target value of the arm 20A is calculated and used as an input to the servo driver. Thus, instead of the target motion generated by the motion generator 63, the emergency motion generator 72 calculates a target angular velocity for performing an emergency motion, that is, a braking operation. 21 and 22 are controlled.
By this braking control, the rotation of the first arm portion 21 and the second arm portion 22 is restricted, and the first arm portion 21 and the second arm portion 22 stop before reaching the operator.
Note that the computer functions as the emergency operation generation unit 72 by executing software installed in advance.

  As described above, according to the work support system 1 according to the present embodiment, it is possible to prevent contact with the arm 20 </ b> A even if the worker moves unexpectedly.

  Furthermore, in this embodiment, the proximity detection unit 71 for detecting workers in the areas A to F performs parallel distributed processing. That is, the two detection systems 71A and 71B are provided, and even if one system 71A (71B) has a problem, an operator can be detected by the other system 71B (71A). Therefore, safety can be further improved.

[Relationship between braking distance and detection distance]
As described above, in the parallel distributed sensing system, the detection distance of the optical position sensor 75 can be changed by changing the reference voltage input from the D / A board 79 (see FIG. 6) to the comparison circuit 77. At this time, if the detection distance of the optical position sensor 75 is larger than the braking distance necessary until the arm 20A stops, the collision between the operator and the arm 20 can be prevented in advance. However, if this detection distance is set to be larger than necessary, the arm 20A cannot approach the operator, and parts and tools cannot be delivered. Therefore, by sequentially changing the detection distance of the optical position sensor 75 according to the movement of the arm 20A by the following method, parts and tools are delivered while preventing collision with the operator.

The detection distance is set by adding the theoretical braking distance ds corresponding to the motion state of the arm 20A and the distance dw with the worker when the arm can be arbitrarily set. The theoretical braking distance ds can be calculated from the moving distance of the hand when the braking control is performed from the model of the arm 20A and the equation of motion. This braking distance depends on the movement state of the arm 20A when the work support system 1 detects the approach to the worker and starts the braking control. Therefore, the braking when performing the movement from the movement plan of the arm 20A in advance is performed. The distance is obtained for each control cycle.
However, the braking distance calculated from the actual braking distance and the model does not match due to the influence of modeling error and the like. Therefore, a braking control experiment was performed at the hand speed of 15 patterns, and an error between the actual braking distance and the braking distance calculated from the model was obtained. Table 1 shows the results of experiments conducted 10 times for each speed pattern.

  Since the standard deviation is sufficiently small with respect to the actual braking distance, it can be said that the braking distance is reproducible. From this result, the relationship between the hand speed and the braking distance error is shown in FIG. This relationship is approximated by the least square method, and added to the braking distance obtained from the model to obtain the braking distance ds used for setting the detection distance.

[Evaluation experiment]
An evaluation experiment of the work support robot according to the present embodiment was performed. FIG. 10 shows the hand trajectory of the arm of the work support robot used in the experiment.
Assuming that the worker is working at the X position shown in the figure, when the hand speed is changed, the set detection distance is appropriate from the distance between the worker and the arm 20A when the arm is stopped. Check if there was. At this time, dw was set to 150 [mm].
Table 2 shows the hand speed, the detection distance, the braking distance, and the distance between the arm and the worker when detecting the approach with the worker.

  It can be seen that the braking distance increases as the hand speed of the arm 20A at the time of approach detection increases. Further, the detection distance until the arm 20A is detected from the operation start position is also increased accordingly. The distance between the arm 20A and the operator when the arm stopped substantially matched the set value dw = 150 [mm].

[Relationship between detection distance and sensor position]
The posture change itself that occurs from when the arm 20A starts the emergency stop operation by the braking control to when it stops is dependent on the angle and angular velocity of each joint at the moment of starting the emergency stop operation. At this time, the distance by which a certain point on the arm 20A rotating around the rotary joint moves until it stops due to the posture change accompanying the braking control depends on the position on the arm 20A.
For example, in the case of an arm connected by a rotary joint, the farther away from the center of rotation, the longer the braking distance. When a rod-shaped object is moving at an angular velocity centered on one end, the distance moved per unit time is the same as the distance from the center increases. Therefore, when stopping after a certain time from a certain moment, the braking distance at this time changes according to the distance from the center.
Therefore, if the arm 20A is to be stopped before colliding with the worker, the braking distance at that time varies depending on the position on the arm 20A. Therefore, the detection distance of each sensor 75 needs to be changed in accordance with “the braking distance of the installation position of each sensor 75 determined according to the motion state of the arm 20A”. That is, the detection distance of the optical position sensor 75 provided in each arm part 21 and 22 is set according to the braking distance corresponding to the speed of each arm part 21 and 22 at that time.

  As described above, the present invention can be implemented in various forms without departing from the spirit of the invention.

(1) Conveying mechanism The conveying mechanism 20 does not have a plurality of joints like the robot arm 20A shown in FIG. 1, but conveys either or both of tools and parts like a linear motion table with one degree of freedom. Anything is acceptable. Further, an articulated robot arm having three or more degrees of freedom may be used. Further, the transport mechanism may be configured as a carriage.
The robot arm 20A constituting the transport mechanism 20 can be moved like a carriage, whether it is drivably attached to the base frame 10 as shown in FIG. It may be attached to.
Thus, the torque limiter is mounted on the drive unit of the transport mechanism that is movable in the work area, and the transport mechanism becomes free when a force greater than a specified value is applied. Further, a sensor is provided in the transport mechanism, and movement of the transport mechanism is suppressed when an operator is detected by the sensor. Specifically, servo control is performed to reduce the speed according to the posture and speed when the work is detected. For example, in the case of a carriage, a servo motor that rotates the wheels is controlled. At that time, the servo control is performed by obtaining an acceleration for stopping the carriage within a predetermined distance based on the equation of motion, speed and position of the carriage. If the transport mechanism is an XY stage, servo control is performed by deriving servo control for reducing the movement of the stage in each axial direction from the equation of motion of the XY stage.

(2) Movement direction of the transport mechanism In the above description, the arm 20A is the horizontal direction as the transport mechanism. However, the movement direction of the transport mechanism may be a vertical direction or a three-dimensional direction instead of horizontal. Of course.

(3) Application The application of the work support system is not limited to automobile assembly.

(4) Sensor The sensor that detects the worker in the proximity region as the transport mechanism moves is not limited to the optical position sensor, and may be a sensor that uses radio waves, ultrasonic waves, or the like. The reference voltage of the comparison circuit is set according to each sensor because the relationship of the detection distance differs depending on the type of sensor.

(5) Parallel distributed processing In the above description, the case where two systems are handled as parallel distributed processing has been described, but three or more systems may be processed in parallel. Of course, the present invention can be configured even if parallel processing is omitted.

(6) Detection distance of each sensor Also in the conveyance mechanism other than the arm, the detection distance of each sensor depends on the attachment position of the sensor and the braking distance based on the movement state of the conveyance mechanism at that position. It is set to avoid contact.

DESCRIPTION OF SYMBOLS 1 Work support system 10 Base frame 20 Arm 21 1st arm part 22 2nd arm part 23 Connection part 30 Drive part 33,34,35,36 Timing pulley 40 Measurement part 50 Control apparatus 60 Support action control part 61 Work model production | generation part 62 Work Estimation Unit 63 Operation Generation Unit 70 Emergency Operation Control Unit 71 Proximity Detection Unit 72 Emergency Operation Generation Unit 75 Optical Position Sensor

Claims (4)

A transport mechanism that transports one or both of a tool and a part, and includes an arm configured by connecting a plurality of arm portions via a connecting portion ;
A drive unit including a motor and a torque limiter mounted on the motor, and operating the transport mechanism;
A detection unit for detecting an operator in an area in the moving direction of the transport mechanism;
An emergency operation generator for controlling the movement of the transport mechanism by driving the motor with a torque smaller than the torque at which the torque limiter is activated when an operator is detected by the detector;
With
When the detection unit detects an operator, the emergency operation generation unit obtains, as a command value, a torque value that does not exceed the operating limit value of the torque limiter from the motion model of the arm. By calculating an angular velocity that is a target value of the arm unit from the angle, the angular velocity, and the command value and inputting the angular velocity to the motor, the transport mechanism is stopped without operating the torque limiter.
Work support system. The detection unit belongs to one of the group systems, and a plurality of sensors arranged at intervals on each side surface of the arm unit, and processing for each group system that processes signals from the plurality of sensors in a distributed manner And comprising
The work support system according to claim 1, wherein the emergency operation generation unit regulates movement of the transport mechanism when receiving an output from a sensor in a processing unit of at least one group system. The processing unit includes a comparison circuit that receives an input of a voltage signal output from the sensor belonging to the group system for each group system,
The operation according to claim 2, wherein each comparison circuit compares an input voltage signal and a reference voltage determined by a detection position, and the emergency operation generation unit brakes the arm according to an output from each comparison circuit. Support system. The work support system according to claim 2 or 3 , wherein a detection distance of each sensor is set according to a braking distance of a set position of each sensor determined based on a motion state of the transport mechanism.