JPH04348887A - Device for inserting rod member into insertion hole and method thereof - Google Patents

Abstract

PURPOSE:To facilitate the insertion of a rod member into an insertion hole even though the insertion hole is not chamferred. CONSTITUTION:A six-axial force sensor 2 for detecting three components forces or torques acting upon a glipper 4 and a compliance element 3 for absorbing horizontal and angular shifts are disposed between a robot arm 1 and the gripper 4. A spool A is moved while it is pressed against a valve body B with a force desginated by the force sensor 2. A spool hole C can be detected since the pressing force decreases. Then the spool A is inserted into thus detected hole C.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for inserting a rod-shaped member into an insertion hole of a member to be attached.

0002

2. Description of the Related Art Conventionally, in the assembly process of various parts, a robot arm is provided with a gripper for removably gripping a rod-shaped member, and the rod-shaped member held by the gripper is
The insertion of a rod-shaped member is automated by inserting it into an insertion hole of a member to be attached. In that case, usually
The opening periphery of the insertion end of the insertion hole of the attached member or the end periphery of the rod-shaped member is chamfered to facilitate insertion of the rod-shaped member into the insertion hole.

0003

[Problems to be Solved by the Invention] However, for example, when the mounted member is a valve body of a hydraulic valve having a spool hole (insertion hole), the rod-like member is inserted into the spool hole of the valve body. In such cases, it is functionally
It is not possible to chamfer both the opening periphery of the insertion end of the spool hole and the periphery of the end of the spool. It is difficult to insert a rod (rod-shaped member).

[0004] The present invention was made in view of this point, and a force sensor and a compliance element are attached to a robot arm, and the insertion hole is searched while detecting the force, even when the chamfering process is not performed. It is an object of the present invention to provide a device and a method for inserting a rod-like member into an insertion hole of an attached member, which can reliably insert the rod-like member into the insertion hole.

[0005]

[Means for Solving the Problems] The invention as claimed in claim 1 is an apparatus in which a robot arm is provided with a gripper for gripping a rod-shaped member, and the rod-shaped member held by the gripper is inserted into an insertion hole of a member to be attached. Compliance elements are interposed between the gripper and the robot arm to absorb horizontal and angular deviations, and six axes detect three components of force and three components of torque acting on the gripper. The structure includes a force sensor and a control means that moves the rod-like member while pressing it against the attached member with a force specified by the force sensor, and detects the insertion hole when the pressing force becomes smaller.

The invention according to claim 2 is a method in which a robot arm is provided with a gripper for gripping a rod-shaped member, and the rod-shaped member held by the gripper is inserted into an insertion hole of a member to be attached. Between the arm and the gripper,
A 6-axis force sensor that detects three components of force and three components of torque acting on the gripper, and a compliance element that absorbs horizontal and angular deviations are interposed, and the gripper is equipped with a 6-axis force sensor that detects the three components of force and three components of torque that act on the gripper. The rod-shaped member is moved while being pressed against the attached member by force, and as this pressing force becomes smaller, an insertion hole is detected, and the rod-shaped member is inserted into the detected insertion hole.

[0007]

[Operation] The rod-shaped member is moved, for example, in a spiral shape while being pressed against the attached member with a force specified by the force sensor. During this movement, the insertion hole is detected as the pressing force becomes smaller. Since the position of the insertion hole is detected in this way, the rod-shaped member is inserted into the detected insertion hole.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing the overall configuration of the device according to the present invention, 1 is a robot arm that grips a rod-shaped member such as a spool of a hydraulic valve via a force sensor 2 and a compliance element 3. A gripper 4 is attached. Specifically, a connecting portion 6 on the gripper 4 side is detachably connected to a connecting portion 5 on the robot arm 1 side, and a force sensor 2 is installed between the robot arm 1 and the connecting portion 5. , a compliance element 3 is interposed between the connecting portion 6 and the gripper 4, respectively.

The force sensor 2 is electrically connected to a sensor controller 7. The sensor controller 7 is connected via a level converter 8 or directly to a robot controller 9. 10 is a robot terminal.

The force sensor 2 detects three-axis components of force (Fx, Fy
, Fz ) and three-axis component torque (Tx , Ty ,
This is a 6-axis force sensor (force/torque sensor, manufactured by BL Autotech Co., Ltd.) that detects Tz) and has the following functions.

(2) By inputting conditional expressions of force and torque to the sensor controller 7, the force and torque are monitored and a signal is output when the conditional expressions are satisfied. This conditional expression is
Multiple items can be stored, and the conditional expression to be monitored can be selected from the outside. In other words, on the robot side,
The load that monitors the force information is carried out by the sensor controller 7.
I can.

(2) Output the actual measured values of force and torque and output them to the robot.

[0014] The compliance element 3 is an RCC (Remote Control Element) that absorbs (corrects) deviations (errors) in the horizontal direction and angular (prying) direction between fitting parts independently without coupling them. Cent
er Compulliance) device is used. These are: ■High pressing rigidity, high compliance with plane direction moment, ■Tilt can be adjusted by using the focal point, and ■Many variations in combination of rigidity in each direction, making it easy to select the appropriate one. Because it can be done.

Next, the basic principle of searching for an insertion hole in a member to be attached will be explained. First, a rod-shaped member is applied to the periphery of the insertion end opening of the insertion hole and slid into the insertion hole of the member to be attached. At this time, since the point of action is far from the focal point of the compliance element, when the rod-like member tilts in the direction of entering the insertion hole, the pressing force decreases and the compliance element tilts in the opposite direction with respect to the insertion hole. , the pressing force increases. Therefore, this property of being easy to slide toward the center of the insertion hole and difficult to slide toward the outside of the insertion hole is utilized. Then, the insertion is made based on the force information detected by the force sensor.

To search for an insertion hole in a member to be attached using this principle, first, a force sensor is used to press a rod-like member against the member to be attached with a specified force.

Then, in this pressed state, in order to uniformly search the position of the insertion hole, the spiral is moved so that it gradually becomes larger, and it is slid in a direction with good conditions (that is, a direction approaching the center of the insertion hole). By moving the rod-shaped member, the rod-shaped member is inserted into the insertion hole of the member to be attached. At this time, whether the rod-shaped member has been inserted into the insertion hole is determined by detecting that the pressing force becomes smaller using the force sensor.

Next, a specific method applied to inserting the spool A into the spool hole C of the valve body B will be described with reference to FIGS. 2 to 9. In addition, in each figure,
The connecting parts 5 and 6 are omitted, and the force sensor 2 and the compliance element 3 are shown in a directly connected state.

(1) First, as shown in FIG. 2, the spool A gripped by the gripper 4 is rough taught.
, move it to just above the spool hole C of the valve body B. At this time, the spool A is floating in space, so as shown in FIG. 9, the pressing force F1 is 0, and it is not receiving any external force (see FIG. 9 for the pressing force below).
.

(2) Then, as shown in FIG. 3, spool A is lowered until it hits the periphery of spool hole C and reaches the specified pressing force. At this time, a pressing force F2 is generated, but no sliding force in the plane direction is generated.

(3) As shown in FIG. 4, spool A begins to move horizontally in a spiral (diverging direction). At this time, as an example, the spool A, which is moving in the opposite direction to the center direction of the spool hole C, rides on the spool hole C, thereby increasing the pressing force F3 and the sliding force f3. also occurs. In addition, at this time, the sliding force f
The absolute value of 3 is less than the static friction force and there is no slippage.

(4) As shown in FIG. 5, the spool A moved inward of the spool hole C due to the spiral movement. At this time, the spool A is tilted so as to enter the spool hole C, so the pressing force F4 becomes smaller and the sliding force f
4 is in the opposite direction to that in FIG. 4, and the static friction force is also smaller.

(5) As shown in FIG. 6, the spiral shape in which the spool A moves becomes larger, the slope is greater than that shown in FIG. 4, and the sliding force f5 is also increased. Moreover, the pressing force F5 becomes large again, and the static frictional force becomes large. At this time, it still doesn't slip.

(6) As shown in FIG. 7, the spiral shape becomes larger and is more tilted than the state shown in FIG. 5, and the sliding force becomes larger. The pressing force F6 becomes smaller, and the static friction force also becomes smaller. In this example, the static friction force is greater than the sliding force f6, and the spool slides toward the center of the spool hole C.

(7) As shown in FIG. 8, when the spool A is in the spool hole C of the valve body B, the pressing force F7 becomes very small, so that the pressure of the valve body B is The force sensor 2 can confirm that the spool has entered the spool hole C. Note that there is a sliding force f7.

Next, an example in which a spool is inserted into a spool hole of a valve body of a hydraulic valve will be described. Note that in order to perform this insertion operation, the force sensor 2
■FTL (PORCE TORQUE LANGU
AGE) Threshold control (parallel communication) that monitors the force and torque conditional expressions set in the sensor using software, ■ Control that the robot reads the actually measured force and torque data and makes a decision ( Serial control).

First, when the robot starts, in step S1, the robot grips the spool with the gripper 4 and makes it float in space.

Then, in step S2, the robot is stopped momentarily and a zero point correction command is sent to the sensor 2. This command subtracts the weight of the gripper 4 and the spool and the torque due to the unbalanced load, and sets the sensor data to the zero point. Therefore, only external force is detected.

In step S3, the tip of the spool is moved to a position (teaching point) at a height of about 1 mm directly above the spool hole.

[0030] Then, in step S4, a contact search is performed. In other words, while lowering the spool, the FTL motor
monitor the force in the Z-axis direction. And step S
5, if the spool hits the periphery of the opening of the spool hole and the pressing force increases and the FTL conditional expression is satisfied,
This is notified to the robot through parallel communication, the descent is stopped, and the process moves to step S6. Also, the maximum descent at this time is 3m.
If it has descended by 3 mm at m, it is determined that it has entered the spool hole without hitting the periphery of the opening of the spool hole, and the hole search operation is omitted and the process proceeds to the next step S7, where center alignment is performed.

After hitting the periphery of the opening of the spool, in step S6, the robot arm 1 is moved horizontally and spirally while monitoring the Z-axis force in FTL mode, and the spool is moved in a spiral manner. Perform a hole search to find a hole. At this time, step S8
If the spool enters the spool hole, the pressing force becomes smaller, and if the FTL conditional expression is satisfied, the robot is notified by parallel communication and the movement is stopped, step S7.
On the other hand, if the spool does not enter the spool hole, the process moves to step S14.

In step S7, the robot arm reads the data of the bending torque applied to the spool through serial communication, moves the robot arm 1 so that each bending torque becomes smaller, and aligns the bending torque with the center. conduct. At this time, the coordinates of the sensor 2 rotate due to the movement of the robot arm 1, but the robot calculates the torque data to match its origin coordinates.

Then, in step S9, the spool is lowered and pushed in while monitoring the Z-axis force in FTL mode. Then, in step S10, it is determined whether the target position has been reached. That is, if the shoulder (edge) of the spool hits the surface or internal edge of the spool hole and there is a pressing force, if the FTL conditional expression is satisfied, the robot is notified by parallel communication and the descent is stopped, and step S11 Move to. If it descends to the insertion position without hitting the shoulder, the target position has been reached, so the flag is set to success in step S12, and the process ends.

If the target position is not reached and there is a shoulder contact (step S11), the shoulder contact is canceled in the same manner as the hole searching operation in step 6. If it is determined in step S13 that the shoulder contact has been released, the centering operation in step S7 and the pushing operation in step S9 are repeated until the spool is lowered to the insertion position. If it has not been released, set a flag=failure in step S14,
finish.

In this flowchart, if a spool hole is found, the spool is then guided and inserted into the spool hole, and if the guide comes off midway through, the spool is inserted into the spool hole. , or if there is a part that is likely to hit the shoulder, the movement point is changed and the same control is performed again based on the flowchart.

Furthermore, in order to shorten the time required to find the spool hole, for example, the direction in which the spool hole is located may be checked and the spool may be moved in that direction. In that case, the spool is pressed against the periphery of the opening of the spool hole, and while the pressing force is monitored, the spool is moved in a circular motion around the pressing point. The spool hole is located in the direction where the pressing force is least due to this operation, so check that direction, move in that direction to reduce the pressing force, and stop when the spool is inserted into the spool hole. . Alternatively, the search may be performed in a straight line. In that case, press the spool at a position shifted from the center of the spool hole in a predetermined direction. At this time, since the direction in which the spool hole is located is known, it is sufficient to move in that direction and stop when the pressing force decreases and the spool enters the hole.

[0037]

According to the present invention, a force sensor and a compliance element are interposed between a robot arm and a gripper, and a bar-shaped member is pressed with a force specified by the force sensor to a predetermined position. As the rod-shaped member is moved in the direction and the pressing force becomes smaller, the insertion hole of the attached member is detected and the rod-shaped member is inserted into the insertion hole, so chamfering cannot be applied to the edge of the insertion hole. Even in such a case, the rod-shaped member can be easily inserted into the insertion hole.

[Brief explanation of the drawing]

1 is a perspective view of the entire system implementing the method of the invention; FIG.

FIG. 2 is an explanatory diagram of the action of the first stage.

FIG. 3 is an explanatory diagram of the second stage operation.

FIG. 4 is an explanatory diagram of the operation of the third stage.

FIG. 5 is an explanatory diagram of the action of the fourth stage.

FIG. 6 is an explanatory diagram of the action of the fifth stage.

FIG. 7 is an explanatory diagram of the action of the sixth stage.

FIG. 8 is an explanatory diagram of the action of the seventh stage.

FIG. 9 is a diagram showing temporal changes in pressing force.

FIG. 10 is a flowchart showing the insertion procedure when the hole is chamfered.

[Explanation of symbols]

1 Robot arm 2 Force sensor 3 Compliance element 4 Gripper 7 Sensor controller (control means) A Spool (rod-shaped member) B Valve body (attached member) C Spool hole

Claims (2)

[Claims] 1. A device in which a robot arm is provided with a gripper for gripping a rod-shaped member, and the rod-shaped member held by the gripper is inserted into an insertion hole of a member to be attached, the gripper and the robot arm A 6-axis force sensor that detects the three-component force and three-component torque acting on the compliance element and the gripper, which is interposed between and control means for moving the rod-shaped member while pressing it against the attached member with a force applied to the attached member, and detecting the insertion hole when the pressing force becomes smaller. Device to be inserted. 2. A method in which a robot arm is provided with a gripper for gripping a rod-shaped member, and the rod-shaped member held by the gripper is inserted into an insertion hole of a member to be attached, the robot arm and the gripper A compliance element that absorbs horizontal and angular deviations and a 6-axis force sensor that detects three components of force and three components of torque acting on the gripper are interposed between the force sensor and the gripper. The rod-shaped member is moved while being pressed against the member to be attached with a force specified by , an insertion hole is detected as this pressing force becomes smaller, and the rod-shaped member is inserted into the detected insertion hole. A method of inserting a rod-shaped member into an insertion hole of a member to be attached.