Automatic assembly device and contact force monitoring program

Abstract

According to this disclosure, in an assembly line having a conveyor for transporting vehicle bodies, when a robot attaches parts to the vehicle body, the contact force between the robot's hands, etc., and the parts, etc., can be monitored, and the robot can be moved back in accordance with the monitored contact force. [Solution] The automatic assembly device according to the present disclosure comprises: a robot 5 positioned on an assembly line having a conveyor for transporting a vehicle body; a buffer unit connected to the tip of the robot 5; a holding means connected via the buffer unit for holding parts; a force gauge 51 for measuring the force applied to the robot 5 via the holding means; and a control unit that, when the measured value of the force gauge 51 exceeds a threshold, stops the main program of an automatic assembly method for attaching the parts held by the holding means of the robot 5 to the vehicle body, outputs a stop command to the conveyor, and executes a subprogram to move the robot 5 in a retraction direction away from the vehicle body.

Description

Technical Field

[0001] The present disclosure relates to an automatic assembly device and a contact force monitoring program.

Background Art

[0002] Patent Document 1 discloses an assembly transfer device capable of assembling parts to a vehicle body with high precision. This assembly transfer device includes a chain conveyor, a hanger, a self-propelled cart, and a robot. The hanger suspends the vehicle body and is pulled by the chain conveyor. The self-propelled cart is mounted with the vehicle body together with the hanger and reciprocates on the component assembly line.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] FIG. 6 is a diagram for explaining an automatic assembly device on a vehicle assembly line. In the above conventional assembly line, the safety mechanism of the automatic assembly device can determine that when assembling the front window W1, which is a component, to the vehicle body 20, the hand 3 of the operator enters the gap between the vehicle body 20 and the front window W1 and may be pinched. When it is determined that a hand or the like is pinched, a sensor of the robot or the like detects the contact and outputs a stop command to the conveyor. However, even when the safety mechanism outputs a stop command to the conveyor, the vehicle body 20 may move forward due to the inertia of the conveyor, and since the robot 5 has stopped, there is a case where the hand may be pinched between the advancing vehicle. The present disclosure has been made to solve such problems, and an object thereof is to provide an automatic assembly device or the like that can prevent hand-pinching accidents and ensure even higher safety.

Means for Solving the Problems

[0005] The automated assembly device according to this disclosure comprises: a robot positioned on an assembly line having a conveyor for transporting a vehicle body; a buffer connected to the tip of the robot; a holding means connected via the buffer and for holding a part; a force gauge for measuring the force applied to the robot via the holding means; and a control unit that, when the measured value of the force gauge exceeds a threshold, stops the main program of an automated assembly method for attaching the part held by the holding means of the robot to the vehicle body, outputs a stop command to the conveyor, and executes a subprogram to move the robot in a retraction direction away from the vehicle body.

[0006] The holding means has a suction pad for adsorbing and holding the component, and the buffer portion includes a spring connected to the suction pad for biasing the suction pad, and a regulating portion for restricting the biased spring.

[0007] The holding means has an adsorption pad for adsorbing and holding the component, and the buffer has a magnet connected to the adsorption pad, and the magnet is configured to be magnetically coupled to a fixing plate at the tip of the robot in a first position, and to be released from the magnetic coupling with the fixing plate at the tip of the robot in a second position and to be magnetically coupled to a fixed wall spaced apart from the fixing plate.

[0008] When the control unit detects that the conveyor has stopped, it terminates the subprogram.

[0009] The contact force monitoring program according to this disclosure is used in an automated assembly device comprising: a robot positioned on an assembly line having a conveyor for transporting a vehicle body; a buffer connected to the tip of the robot; a holding means connected via the buffer and for holding a part; and a force gauge for measuring the force applied to the robot via the holding means. The program stops the automated assembly method for attaching the part held by the robot's holding means to the vehicle body when the measured value of the force gauge exceeds a threshold, outputs a stop command to the conveyor, and causes the computer to move the robot in a retraction direction away from the vehicle body. [Effects of the Invention]

[0010] According to this disclosure, in an assembly line having a conveyor for transporting vehicle bodies, when a robot attaches parts to the vehicle body, the contact force between the robot's hands, etc., and the parts, etc., can be monitored, and the robot can be moved back in accordance with the monitored contact force. [Brief explanation of the drawing]

[0011] [Figure 1] This is an enlarged side cross-sectional view of the tip of the automatic assembly device according to the embodiment. [Figure 2] This is an enlarged side cross-sectional view of the tip of an automatic assembly device according to another embodiment. [Figure 3] This is a flowchart of the automated assembly method (main program) according to the embodiment. [Figure 4] This is a diagram illustrating an automated assembly method according to an embodiment. [Figure 5] This is a flowchart of the contact force monitoring method (subprogram) according to the embodiment. [Figure 6] This is a diagram illustrating an automated assembly device in a vehicle assembly line. [Modes for carrying out the invention]

[0012] Specific embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings have been simplified as appropriate.

[0013] Referring to Figure 6, the overall structure and challenges of the vehicle assembly line of this disclosure will be explained. In a vehicle assembly line where vehicles are continuously transported by a conveyor, the automated assembly device (also called a material handling system) 10 has a robot 5 (Figure 6) that performs tasks in cooperation with an operator. Vehicle bodies 20 before assembly are placed on the conveyor and sent sequentially, stopping at predetermined positions, and the operator assembles the vehicle parts held by the robot 5 of the automated assembly device 10.

[0014] When a part (for example, the front window W1) held by the robot 5 is assembled to the vehicle body 20 in the direction of arrow A in Figure 6, various sensors may detect if a worker's hand 3 or the like is caught between the part and the vehicle body 20. At this time, the robot 5 moves to a predetermined location in the direction of arrow B in Figure 6 (away from the vehicle body) and then stops its operation. At the same time, a conveyor stop command is output to the assembly line. This prevents such pinching accidents. However, if the conveyor continues to move forward by inertia for a distance equal to the distance of inertia after the conveyor stop command (especially when assembling a part to the front of the vehicle body), there is a risk that a hand 3 or the like may be caught between the stopped robot 5 and the vehicle body 20 which is on the conveyor moving forward by inertia.

[0015] This disclosure prevents pinching accidents by configuring the components around the suction pad that holds the component in place when the component comes into contact with a hand or other object, thereby mechanically securing a gap (i.e., a buffer). Furthermore, it prevents hand pinching accidents by executing a retraction action of the robot in accordance with the measured contact force between the component and the hand or other object.

[0016] FIG. 1 is an enlarged side sectional view of the tip of the automatic assembly device. In FIG. 1, the direction of arrow A indicates the mounting direction (the traveling direction of the robot), and the direction of arrow B indicates the retreat direction (opposite to the traveling direction of the robot). A hollow housing 15 is connected to a fixing plate 16 fixed to a robot (5 in FIG. 6, not shown in FIG. 1). A part of the ceiling of the housing 15 has a through hole 15a formed therein. As shown in the lower figure of FIG. 1, the through hole 15a is formed obliquely so that the size of the hole increases toward the inside of the housing 15 (fixing plate 16).

[0017] A fitting portion 13 is provided which is formed to fit with the through hole 15a. In other words, this fitting portion 13 is formed so that the outer diameter increases toward the hollow inside of the housing 15 (fixing plate 16). Usually, the inclined side surface of the fitting portion 13 biased by the spring 14a abuts against the through hole 15a having the inclined side surface of the housing 15, and the movement of the fitting portion 13 is restricted. That is, the through hole 15a and the fitting portion 13 function as a restricting portion of the spring 14a. One surface of this fitting portion 13 (the side of the hollow inside of the housing 15) and the fixing plate 16 are connected via a spring 13 inside the hollow of the housing 15. The other surface of the fitting portion 13 (the outside of the housing 15) is connected to the suction pad 11 via the holding rod 12.

[0018] The suction pad 11 is configured to suck a part (for example, a glass front window). The suction pad 11 is made of a soft elastic body such as rubber, for example, and the tip of the tapered suction surface can be closely adhered to and held on the smooth surface of the front window W1. Thereby, the front window W1 can be attached to the front window mounting portion 24 (FIGS. 5 and 6) of the vehicle body 20. Note that the suction pad is an example of holding means for holding a part, and various modifications are conceivable.

[0019] As shown in the lower diagram of FIG. 1, when a part (front window W1) comes into contact with a hand or the like, the spring 14a contracts, causing the suction pad 11, the holding rod 12, and the fitting portion 13 to move toward the fixing plate 16 along the arrow B. That is, the configuration in which the spring 14a contracts and the suction pad 11, the holding rod 12, and the fitting portion 13 can move constitutes a buffer portion. The amount by which the spring contracts, that is, the amount by which the suction pad 11, the holding rod 12, and the fitting portion 13 move toward the fixing plate 16, can be set to be longer than the inertial travel distance of the conveyor. Thereby, it is possible to prevent injury when the hand is caught.

[0020] FIG. 2 is an enlarged side cross-sectional view of the tip of an automatic assembly device according to another embodiment. In another embodiment, a magnet 14b may be used instead of the spring 14a. As shown in the upper diagram of FIG. 2, normally, the magnet 14b connected to the fitting portion 13 is magnetically coupled to the metal inner wall 15b around the through hole 15a of the housing 15. On the other hand, as shown in the lower diagram of FIG. 2, when a part (front window W1) comes into contact with a hand or the like, the magnetic coupling between the magnet 14b and the metal inner wall 15b of the housing 15 is released. As a result, the suction pad 11, the holding rod 12, and the fitting portion 13 move toward the fixing plate 16 along the arrow B, and the magnet 14b and the metal inner wall 16b are magnetically coupled. That is, the magnetic coupling between the magnet 14b and the metal inner wall 15b of the housing 15 or the metal inner wall 16b of the fixing plate 16, and the configuration in which the suction pad 11, the holding rod 12, and the fitting portion 13 can move constitutes a buffer portion. The amount by which the suction pad 11, the holding rod 12, and the fitting portion 13 move toward the fixing plate 16 along the arrow B can be set to be longer than the inertial travel distance of the conveyor. Thereby, it is possible to prevent injury when the hand is caught.

[0021] The buffer portion connected to the tip of the robot includes, but is not limited to, the two embodiments described above. The buffer portion can use various configurations that can retreat at least by the inertial travel distance of the conveyor.

[0022] <Automatic Assembly Method> The automated assembly method according to the embodiment will be described with reference to Figures 3 and 4. Figure 3 is a flowchart of the automated assembly method according to the embodiment. Figure 4 is a diagram illustrating the automated assembly method according to the embodiment. The program for mounting the parts to the vehicle body by executing the automated assembly method shown in Figure 3 is also called the main program. The main program is executed by the control unit (computer including a processor and memory, etc.) of the automated assembly device.

[0023] First, robot 5 moves to the synchronization start position SP1 (see Figure 4) (step S101). Next, robot 5 (its control unit) determines whether or not it has received a synchronization start signal from the speed sensor located on the side of conveyor C1 (step S102). The synchronization start signal includes the transport speed of the conveyor that transports the vehicle.

[0024] If robot 5 receives a synchronization start signal from the speed sensor (YES in step S102), robot 5 moves from the synchronization start position SP1 (see Figure 4) to the assembly-ready position SP2 (see Figure 4) (step S103). On the other hand, if robot 5 does not receive a synchronization start signal (NO in step S102), robot 5 repeats the process from step S1.

[0025] Next, the robot 5 obtains from the line light sensor 120 the displacement from the position where the window is held by the holding means to the assembly position SP2 (see Figure 4) (step S104). Next, the robot determines whether the values ​​of each line light sensor are within a predetermined range from zero (step S105).

[0026] If the values ​​of each line light sensor 120 are within a predetermined range from zero (YES in step S105), the robot 5 moves from the assembly-possible position SP2 (see Figure 4) to the assembly position SP3 (see Figure 4) (step S107). Then, at the assembly position SP3 (see Figure 4), the robot 5 assembles the front window W1 to the predetermined assembly position (mounting part 24) of the vehicle (step S108).

[0027] On the other hand, if the values ​​of each line light sensor are not within a predetermined range from zero (step S105NO), the robot 5 corrects the deviation from the position where the part is held by the holding means to the assembly position based on the values ​​of the line light sensors (step S106). Details of the correction method are omitted (step S106). The robot then repeats the process from step S103 until the values ​​of each line light sensor 120 are within a predetermined range from zero.

[0028] Thus, in the automated assembly method according to the embodiment, the deviation from the position where the window is held by the holding means to the position where it can be assembled is corrected. With this configuration, the automated assembly system according to Embodiment 1 can automatically assemble the window to the correct position even if the position where the robot's holding means holds the window is slightly off relative to the vehicle being transported by the conveyor.

[0029] <Robot retreat action> Figure 5 is a flowchart of the contact force monitoring method (subprogram) according to the embodiment. More specifically, this method ensures safety by retracting the robot in response to the contact force between the part held by the robot and a hand, etc., during automatic assembly. The subprogram is a subprogram that is executed in a separate thread from the main program described above. Both the main program and the subprogram are executed by the control unit of the automatic assembly device (a computer including a processor and memory, etc.).

[0030] The control unit of the automated assembly device monitors the contact force between the part held by the robot and a hand or the like using a force gauge 51 (step S200). The force gauge 51 may be built into the robot 5, or it may be inserted between the material handling and the robot tool flange, as shown in Figure 6. The force gauge 51 can measure the force applied to the robot 5 via the holding means that holds the part.

[0031] Next, if the force gauge value is above the threshold (YES in step S201), the control unit of the automatic assembly device stops the main program described in Figures 3 and 4 and continues tracking to synchronize with the conveyor (step S202). By continuing this tracking, if the measured contact force threshold is exceeded, the robot operation can be switched to perform a retraction operation while maintaining synchronized tracking. In this way, if the robot operation is completely stopped by the safety function, synchronized tracking will not be possible, and the robot can avoid being caught in a vehicle that is moving forward by inertia. This force gauge threshold is a reference value for performing the robot's retraction operation when executing the automatic assembly method, and is set to be smaller than the load that completely stops the robot (e.g., 280N) (e.g., 200N). That is, according to the force gauge value, robot stopping load > robot operation switching load > normal mounting operation load.

[0032] The control unit of the automatic assembly device outputs a stop command to the conveyor operation control unit (computer including processor and memory, etc.) (step S203). The control unit of the automatic assembly device moves the robot 5 a predetermined distance in the retraction direction (arrow B in Figure 6) (step S204). When the control unit of the automatic assembly device detects that the conveyor has stopped from the conveyor speed sensor or the like mentioned above (YES in step S205), it terminates this contact force monitoring program. If the conveyor speed sensor mentioned above is 0 mm / s, the control unit of the automatic assembly device may receive the sensor signal and determine that the conveyor has stopped. Alternatively, the stop of the conveyor may be determined by other stop sensors.

[0033] As explained above, in addition to the configuration of the buffer section of the holding means for holding parts, the contact force between a hand or other object and the part can be monitored, and the robot can be retracted according to the monitored contact force. This prevents accidents in which a worker's hand or other object is caught between the material handling equipment and the robot body, even if the conveyor moves due to inertia.

[0034] In the examples described above, the program (including the contact force monitoring program) includes a set of instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more of the functions described in the embodiments. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrical, optical, acoustic or other forms of propagating signals.

[0035] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of Symbols]

[0036] 5 Robots 10 Automatic assembly device 11 Suction pads 12 Holding rod 13. Fitting part 14 Magnets 14b Magnet 15 cabinets 15a through hole 15b Metal interior wall 16 Fixed plate 16b Metal interior wall 20 car bodies 24 Mounting part 51 Force Gauge 120-line optical sensor C1 Dibear W1 Front Windshield

Claims

1. A robot positioned on an assembly line that has a conveyor for transporting vehicle bodies, A buffer unit connected to the tip of the robot, A retaining means that is connected via the aforementioned buffer portion and holds the component, A force gauge for measuring the force applied to the robot via the holding means, When the measured value of the force gauge exceeds a threshold, the control unit stops the main program of the automatic assembly method for attaching the part held by the robot's holding means to the vehicle body, outputs a stop command to the conveyor, and executes a subprogram to move the robot away from the vehicle body. An automated assembly device equipped with [the following features].

2. The holding means has a suction pad that attracts and holds the component, The cushioning portion is connected to the suction pad and includes a spring that biases the suction pad, The automatic assembly device according to claim 1, further comprising a regulating unit for regulating the biased spring.

3. The holding means has a suction pad that attracts and holds the component, The cushioning portion has a magnet connected to the suction pad, The automatic assembly device according to claim 1, wherein the magnet is configured to be magnetically coupled to a fixing plate at the tip of the robot in a first position, and to be magnetically coupled to a fixed wall separated from the fixing plate at the tip of the robot in a second position.

4. The automatic assembly apparatus according to claim 3, wherein the control unit terminates the subprogram when it detects that the conveyor has stopped.

5. A robot positioned on an assembly line that has a conveyor for transporting vehicle bodies, A contact force monitoring program used in an automatic assembly device comprising: a buffer connected to the tip of the robot; a holding means connected via the buffer and for holding a component; and a force gauge for measuring the force applied to the robot via the holding means, A contact force monitoring program that, when the measured value of the force gauge exceeds a threshold, stops the automatic assembly method for attaching the part held by the robot's holding means to the vehicle body, outputs a stop command to the conveyor, and causes the computer to move the robot in a retraction direction away from the vehicle body.

Images