JP2015085501A - Robot, robot system and robot control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently fit one object into an opening of the other object.SOLUTION: A robot for fitting an opening of a first object onto a protrusion of a second object includes a force sensor and hands. The robot grips the first object by one of the hands and moves the opening of the first object closer to the protrusion of the second object. Further, a robot control device for controlling the robot such that the opening of the first object is moved closer to the protrusion of the second object can also execute operation of the robot which includes the force sensor and the hands, grips the first object by one of the hands and fits the opening of the first object onto the protrusion of the second object.

Description

  The present invention relates to a robot, a robot system, and a robot control apparatus.

  At work sites such as manufacturing, automation of work that has been performed manually has been attempted by using robots for work such as assembly. In the assembly work by the robot, there is a case where an object such as a part is grasped by a hand at the tip of the robot arm and assembled to another object. In such an operation, for example, there is a case where an insert is brought into contact with the insert, and the insert is inserted into the insert by force control in the contacted state. In such a case, as a method of bringing the insert into contact with the insert, for example, as described in Patent Document 1, an object having a hole that is an insert placed on a table or the like On the other hand, a method of moving a workpiece which is an insert grasped by a robot hand can be considered.

JP 2010-137299 A

  In the method described in Patent Document 1, it is necessary to grasp in advance the position of the hole of the object that is the object to be inserted. As a method of grasping the position of the hole, for example, the object is imaged by a camera, A method for detecting the position of a hole from an image can be considered. However, for example, when the insert is a gear, the size of the hole of the gear may be small, and it may be difficult to accurately grasp the position of the hole of the gear. As a result, the shaft that is the insert grasped by the robot hand is brought into contact with a position far from the gear hole, and it takes time to insert the shaft into the gear hole. In some cases, the shaft cannot be brought close to the gear hole, and the shaft cannot be inserted into the gear hole.

(1) One aspect of the present invention is a robot that inserts an opening of a first object into a protrusion of a second object, and includes a force sensor and a hand. The robot grips a first object and brings the opening of the first object closer to the protrusion of the second object.
According to this configuration, when the first object having the opening is brought close to the protrusion, the surface of the protrusion is larger than the area of the opening, so that the protrusion can be easily detected by an image or the like. It becomes easy to insert the target object into the second target object.

(2) Another aspect of the present invention is the robot described above, wherein the second object is placed.
According to this configuration, when the second object is placed, it is easy to insert the first object into the second object by setting the projection of the second object as the target position. Become.

(3) Another aspect of the present invention is the robot described above, wherein when the opening of the first object is moved with the second object as a target, the first object is the second object. A contact point that is a position at which the first object contacts the second object is set by setting a displacement point that is a position displaced in a predetermined direction from an initial contact point that is a position where the object first contacts the object. Operates to move the first object while contacting the second object so as to approach the initial contact point from the set displacement point.
According to this configuration, the position where the second object is included in the opening of the first object as a whole can be efficiently searched. Therefore, the second object can be efficiently fitted into the opening of the first object.

(4) Another aspect of the present invention is the above-described robot control device, wherein the distance between the initial contact point and the displacement point is a distance based on an error in the position of the first object. .
According to this configuration, since the range in which the first object is brought closer is determined based on the error, a position that may be a position where the second object is included in the opening of the first object is searched. Is done.

(5) Another aspect of the present invention is the robot control device described above, wherein the contact point covers a region having a predetermined width from a line segment connecting the displacement point and the initial contact point. The first object is moved along
According to this configuration, a potential position where the second object is included in the opening of the first object is searched without omission.

(6) Another aspect of the present invention is the above-described robot control device, wherein a direction different from the predetermined direction from the initial contact point when the second object is not detected in the region. Then, a displacement point is reset to the position displaced to, and the operation of the robot is controlled to move the first object so that the contact point approaches the initial contact point from the reset displacement point.
According to this configuration, a position where the second object is included in the opening of the first object is reliably searched.

(7) Another aspect of the present invention is a robot system including a robot and a robot control device that controls the operation of the robot, wherein the robot opens the opening of the first object to the second A robot that is inserted into a protrusion of an object, and includes a force sensor and a hand, the first object is gripped by the hand, and the robot controller is configured to control the first object. In the robot system, the operation of the robot is controlled so that the opening is brought close to the protrusion of the second object.
According to this configuration, when the first object having the opening is brought close to the protrusion, the surface of the protrusion is larger than the area of the opening, so that the protrusion can be easily detected by an image or the like. It becomes easy to insert the target object into the second target object.

(8) Another aspect of the present invention includes a force sensor and a hand, the first object is gripped by the hand, and an opening of the first object is formed on the second object. It is a robot control device that controls the movement of the robot inserted into the protrusion so that the opening of the first object approaches the protrusion of the second object.
According to this configuration, when the first object having the opening is brought close to the protrusion, the surface of the protrusion is larger than the area of the opening, so that the protrusion can be easily detected by an image or the like. It becomes easy to insert the target object into the second target object.

It is a schematic diagram of a robot system concerning this embodiment. It is a block diagram which shows the function structure of the robot system which concerns on this embodiment. It is a block diagram which shows an example of the flow of control in the robot system which concerns on this embodiment. It is a flowchart which shows the robot control processing which concerns on this embodiment. It is a figure which shows an example of a search area | region. It is a figure which shows the other example of a search area | region. It is a figure which shows an example of a search path | route. It is a figure which shows the other example of a search path | route. It is a figure which shows the further another example of a search path | route. It is a figure which shows the further another example of a search path | route. It is a figure which shows the other example of a function structure of the robot control apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a robot system 1 according to the present embodiment.
The robot system 1 includes a robot control device 10, a robot 20, and one or a plurality (two in this example) of imaging devices 30. The robot control device 10, the robot 20, and the imaging device 30 are connected so that they can communicate with each other.

  The robot control device 10 controls the operation of the robot 20. The robot control apparatus 10 causes the robot 20 to grip a first object (for example, a gear W) as an object and controls its position and posture. Here, when the robot control apparatus 10 moves the opening of the first object with the projection (for example, the insertion pin A) of the second object as a target, the first object is moved to the second object. A displacement point that is a position displaced in a predetermined direction from an initial contact point that is a position where the object first contacts is set, and a contact point that is a position where the first object contacts the second object. The operation of the robot is controlled so as to move the first object while contacting the second object so as to approach the initial contact point from the set displacement point.

  When controlling the operation of the robot 20, the robot control device 10 executes force control, for example. The force control is a method for controlling the force acting on the movable part 21 (described later) of the robot 20 so as to approach a value suitable for the intended work. Further, the robot control apparatus 10 may use another control method, for example, a visual servo when bringing the first object close to the second object. More specifically, the visual servo refers to the operation of the robot 20 so that the position of the object indicated by the current image including the object currently captured by the imaging device 30 approaches the position of the object indicated by the target image. It is a technique to control. Here, the target image is an image including an object placed at a target position as a target.

The robot 20 operates in accordance with a control signal from the robot control apparatus 10 and performs a predetermined operation. The robot 20 assembles the object W so that the work content of the robot 20 is such that one end of the insertion pin A is inserted into the opening surface of the object W to be worked on the work table T, for example. It is. The object is also called a workpiece.
The robot 20 includes one or a plurality of (two in this example) arms 22, a hand 26 provided at the tip of the arm 22, and a force sensor 25 provided at the wrist portion of the arm 22. . The wrist portion of the arm 22 is a portion between the tip portion of the arm 22 and the hand 26. The arm 22 includes one or a plurality of (in this example, six on each of the left and right) joints 23 and one or a plurality of (in this example, five on each of the left and right) links 24.

The robot 20 is a robot that inserts an opening of a first object (for example, the object W) into a protrusion (for example, an insertion pin A) of the second object, and is a force sensor (for example, a force sense). Sensor 25) and a hand (for example, hand 26), the first object is gripped by the hand, and the opening of the first object is brought close to the protrusion of the second object.
The force sensor 25 detects a force and a moment acting on the hand 26, for example. The force sensor 25 outputs a sensor value indicating the detected force or moment to the robot controller 10. The sensor value is used for force control of the robot 20 in the robot control device 10, for example. The force sensor 25 is, for example, a 6-axis force sensor. The six-axis force sensor is a sensor that can simultaneously detect six components, ie, a force component in the translational three-axis direction and a moment component around the three rotation axes. The translational three axes are, for example, three coordinate axes (X axis, Y axis, Z axis) that are orthogonal to each other and that form a three-dimensional orthogonal coordinate system. The three rotation axes are, for example, each of the three coordinate axes. The number of components detected by the force sensor 25 is not limited to six components, and may be, for example, three components (three-axis force sensor). The force sensor 25 is also called a force detection unit.

The hand 26 includes, for example, four finger-shaped components. The finger-shaped component is simply called a finger. The hand 26 can grip an object (for example, the object W) using a finger. Here, the hand 26 can grip one of the surfaces of the object so as to be perpendicular to any coordinate axis (for example, the Z axis).
The hand 26 may be detachable from the tip of the arm 22. The hand 26 can be said to be a kind of end effector. That is, the robot 20 may be provided with an end effector other than the hand 26 in place of the hand 26 or together with the hand 26. An end effector is a member that performs operations such as gripping, lifting, lifting, adsorbing, and processing an object. The end effector can take various forms such as a hand hook, a suction cup, and the like. Further, the number of end effectors is not limited to one for each arm 22, and two or more end effectors may be provided.

  The unit including the arm 22, the force sensor 25, and the hand 26 forms the movable portion 21. The movable part 21 is also called a manipulator. In the example shown in FIG. 1, the robot 20 includes two movable parts 21. The movable unit 21 includes a drive unit for operating each unit such as the joint 23 and the hand 26, for example, an actuator (not shown). The actuator includes, for example, a servo motor, an encoder, and the like. The encoder encodes the displacement detected by itself and converts it into an encoder value, and outputs the converted encoder value to the robot controller. The encoder value is used for feedback control on the robot 20 in the robot control apparatus 10.

The robot 20 drives each joint 23 in conjunction with each other in accordance with a control command input from the robot control device 10. As a result, the robot control apparatus 10 can move the target position set at the tip of the arm 22 or the like to a desired position within a predetermined movable range, or can point it in a desired direction. This attention position is called an end point. An end point is also called an end point. Further, the robot control apparatus 10 can grip or release an object or the like by driving the hand 26.
The end point is not limited to the distal end portion of the arm 22 and may be the distal end portion of an end effector such as the hand 26, for example.

  The imaging device 30 captures an image representing the work area of the robot 20 and generates image data indicating the captured image. In the example shown in FIG. 1, the work area of the robot 20 is a three-dimensional space that is a workable area on the worktable T by the movable part 21, and is an area that includes an end point of the movable part 21. On the work table T, two imaging devices 30 arranged at different positions are directed to one end of an insertion pin A arranged on the work table T. The imaging device 30 is, for example, a visible light camera, an infrared camera, or the like. The imaging device 30 outputs the generated image data to the robot control device 10.

  In the example shown in FIG. 1, one insertion pin A stands upright on the work table T in the vertical direction. The insertion pin A is a two-stage shaft member each having a two-stage radius. In the middle of one end and the other end of the insertion pin A, a step portion with a changing radius is formed. Here, the end face with the smaller radius is called one end, and the end face with the larger radius is called the other end. The other end of the insertion pin A is supported on the work table T, and one end is directed upward. In this arrangement, one end, the stepped portion, and the other end are horizontal.

  Here, the object W is a flat plate having an opening at the center thereof, for example, a gear. The smaller radius of the insertion pin A is smaller than the radius of the opening of the object W by a predetermined tolerance, and the larger radius of the insertion pin A is larger than the radius of the opening of the object W. Therefore, when the opening portion of the object W is disposed immediately above the insertion pin A, the insertion pin A is inserted into the opening portion by moving the object W directly below. When a force is applied to the target portion W in the direction from one end of the insertion pin A to the other end, the surface of the target object W (the lower surface) of the main surface is the stepped portion of the insertion pin A. The object W is supported by the step portion of the insertion pin A. The main surface is a plane that forms a flat plate. In addition, the surface directed upward from the main surface is referred to as an upper surface.

The configuration of the robot system 1 described above is merely an example for explaining the outline of the present embodiment. That is, the configuration of the robot system 1 described above is not limited to the configuration described above, and may have other configurations.
For example, FIG. 1 shows an example in which the number of joints 23 (number of axes) is six on each of the left and right sides (six axes), but the number of joints 23 may be less than six or less than six. May be more. The number of links 24 is determined according to the number of joints 23. Further, the shape, size, arrangement, and structure of members such as the joint 23, the link 24, and the hand 26 may be appropriately changed.

  Further, the installation position of the imaging device 30 is not limited to the work table T as shown in FIG. Further, instead of or in addition to these imaging devices 30, the imaging device 30 may be provided at the distal end portion, the trunk portion, the head portion, or the like of the arm 22. Further, the imaging device 30 may be connected to the robot 20 instead of the robot control device 10. In that case, the image data generated by the imaging device 30 is input to the robot control device 10 via the robot 20.

FIG. 2 is a block diagram showing a functional configuration of the robot system 1 according to the present embodiment.
The robot 20 includes a drive control unit 200. Based on the control signal input from the robot control device 10, the encoder value acquired by the actuator, the sensor value acquired by the force sensor 25, and the like, the drive control unit 200 indicates the position of the end point with the control signal. The actuator is driven so that the target position is reached. Note that the current position of the end point can be obtained from, for example, an encoder value in the actuator.

  The robot control apparatus 10 includes a force control unit 120 and an image acquisition unit 140. The force control unit 120 includes a sensor information acquisition unit 122 and a trajectory generation unit 124.

  The force control unit (control unit) 120 performs force control (also referred to as force sense control) based on sensor information (sensor values indicating force information and moment information) from the force sensor 25 of the robot 20. The force control is a position and force control method for setting the force applied from the outside to the hand of the robot (hand 26 or the like) to a value suitable for the intended work.

  In order to perform force control, it is necessary to detect the force and moment applied to the end effector such as the hand 26, but the method of detecting the force and moment applied to the end effector is limited to that using a force sensor. Absent. For example, it is possible to estimate the external force exerted on the end effector from each axis torque value of the arm 22. Therefore, in order to perform force control, the arm 22 only needs to have means for acquiring a force applied directly or indirectly to the end effector.

  The sensor information acquisition unit 122 acquires sensor information (such as detected sensor values) output from the force sensor 25 of the robot 20. The sensor information acquisition unit 122 can also be called a force detection unit.

  The trajectory generation unit 124 determines the moving direction and moving amount of the end points by force control. Further, the trajectory generation unit 124 determines a target angle of each actuator provided in each joint 23 based on the moving direction and moving amount of the end points. In addition, the trajectory generation unit 124 generates a command value that moves the arm 22 by a target angle and outputs the command value to the robot 20. The trajectory generation process, the target angle determination process, the command value generation process, and the like performed by the trajectory generation unit 124 can use various general techniques, and thus detailed description thereof is omitted.

  In the robot 20 having a joint, when the angle of each joint is determined, the position of the end point is uniquely determined by forward kinematics processing. In other words, an N-joint robot can express one target position by N joint angles. Therefore, if the set of N joint angles is one target joint angle, the trajectory of the end point is a set of target joint angles. Can be considered. Therefore, the command value output from the trajectory generation unit 124 may be a value related to a position (target position) or a value related to a joint angle (target angle).

The force control unit 120 generates a command value (here, a target angle) so that the input sensor value becomes a target value corresponding to the target position and target posture.
Regarding the processing performed by the force control unit 120, the position of the opening of the first object (for example, the object W) is set to the end of the projection (for example, the insertion pin A) of the second object. A case where the second object is inserted into the opening of the first object according to the position will be described as an example. Here, it is assumed that the protruding portion of the second object is placed on the work table T and the position and posture thereof are fixed.

The force control unit 120 is given a target value corresponding to a target position at which one end of the second object approaches at a predetermined direction and speed as time elapses.
However, when the opening of the first object is brought close to one end of the second object, the robot control apparatus 10, for example, uses the second object indicated by the image data acquired by the image acquisition unit 140. You may provide the control part which detects the axis | shaft of a 2nd target object from an image using an image recognition technique, for example. The said control part controls operation | movement of the robot 20 so that a 1st target object may be made to approach the position of the detected axis | shaft. When approaching the first object, the robot control apparatus 10 may use visual servo.
When the center position at one end of the second object is set as the target position of the center of the opening of the first object, an error occurs that the center position of the second object deviates from the target position. Sometimes. By shifting the position of the opening of the first object from the position of the one end of the second object, one end of the second object is formed as an opening in the main surface of the first object. It may come into contact with the unexposed part (planar part).

  The force control unit 120 determines whether or not the planar portion of the first object has come into contact with one end of the second object. For example, when the change per unit time of the sensor value input from the force sensor 25 is more rapid than the change in the predetermined sensor value, the force control unit 120 determines that the contact has been made. In this case, the first target portion receives a reaction force from the second target object. Thereafter, the force control unit 120 stops applying force to the first object. In other cases, the force control unit 120 determines that there is no contact.

  Then, the force control unit 120 determines whether one end of the second object is inserted into the opening of the first object. Here, the force control unit 120 applies, for example, a force having a predetermined magnitude in the direction from one end to the other end of the second object on the first object, and inputs from the force sensor 25. When the magnitude of the force in the direction indicated by the sensor value is smaller than a predetermined magnitude threshold, it is determined that the sensor is inserted. This threshold value is a value smaller than the force applied to the first object, for example. In that case, the reaction force received from the second object is reduced or lost in the first object. In other cases, the force control unit 120 determines that it is not inserted.

  When it is determined that one end of the second object is not inserted, the plane portion of the first object is in contact with one end of the second object. Here, the position in contact with the center of one end of the second object on the surface of the first object is called a contact point. In particular, the contact point when the flat portion of the first object first contacts one end of the second object is called the initial contact point. In this case, the force control unit 120 causes the first target to shift to a position (displacement point) that is shifted by a predetermined amount (offset amount) in a predetermined direction (offset direction) from the initial contact point. Translate things. The displacement point is one point on the surface portion of the first object that is displaced from the initial contact point by a predetermined offset amount in a predetermined offset direction.

Here, the offset amount d is based on the error (accuracy) of the position of the first object when the center position of the first object and the center of one end of the second object are the target positions. It may be determined. This error is a deviation of the contact point from the target position. The offset amount may be set to 6σ, for example, based on the standard deviation σ in the direction of one coordinate axis in the horizontal plane direction, which is a statistic indicating the magnitude of the error distribution. 6σ indicates an error range (one side 3σ) generated with a probability of approximately 99.7% when it is assumed that the error probability in the coordinate axis direction follows a normal distribution. Further, the offset direction may be arbitrarily set as long as it is in a plane parallel to the surface portion of the first object.
In the force control, generally, the accuracy when one object is moved while being in contact with another object is higher than the accuracy when the object is moved without being contacted. That is, the offset amount d is larger than an error due to the control of moving the first object while making contact with the second object using force control.

Thereafter, the force control unit 120 moves the first object so that the contact point approaches the initial contact point from the displacement point while bringing the surface portion of the first object into contact with one end of the second object. (Exploring action) Here, the direction from the displacement point to the initial contact point is opposite to the offset direction. When moving the first object so that the contact point approaches the initial contact point, the force control unit 120 is on a path covering a region having a predetermined width from a line segment connecting the displacement point and the initial contact point. move. Thereby, the position of the first object in which the region of the opening of the first object is included in one end of the second object in a plan view is searched. Such an area is called a search area. An example of the search area will be described later.
While moving the first object so as to approach the initial contact point from the displacement point, the force control unit 120 determines whether one end of the second object is inserted into the opening of the first object. judge. The process related to this determination may be similar to the process of determining whether one end of the second object is inserted into the opening of the first object described above.

  If it is determined that it has been inserted, the force control unit 120 adjusts the posture of the first object, and the center axis of the opening of the first object matches the center axis of the second object. Let Thereafter, the first object is moved (inserted) from one end to the other end (for example, downward). Unreasonable force on the first object or the second object by moving the first object while the center axis of the opening of the first object and the center axis of the second object are inclined. To avoid the risk of damage or breakage. When adjusting the posture of the first object, the force control unit 120 may use impedance control.

When one end of the second object is not inserted into the opening of the first object and the contact point reaches the initial contact point, that is, one end of the second object is not detected in the search area. There is a case.
In this case, the force control unit 120 may change the offset direction described above and reset the displacement point at a position shifted by a predetermined offset amount in the offset direction changed from the initial contact point.
Thereafter, the force control unit 120 moves the first object so that the contact point shifts from the initial contact point to the reset displacement point, and within the search region so that the contact point approaches the initial contact point from the displacement point. The process of moving the first object is repeated. Then, when the contact point reaches the initial contact point without inserting one end of the second object into the opening of the first object, the process of resetting the displacement point is repeated.

  The number of repetitions N of processing can be arbitrarily set in advance. N is, for example, 2 or 4. However, the offset direction in each process is determined in advance according to the number N of repetitions so that the same offset direction is not repeated. For example, k (k is an integer greater than 1 and less than or equal to N) times, and the offset direction is repeated clockwise or counterclockwise with respect to the initial offset direction from the initial contact point (k−1) · 360. It may be set as ° / N.

  The image acquisition unit 140 acquires image data captured by the imaging device 30. The image acquisition unit 140 uses the acquired image data for the above-described control, for example.

Next, an example of a control flow in the robot system 1 according to the present embodiment will be described.
FIG. 3 is a block diagram illustrating an example of a control flow in the robot system 1 according to the present embodiment.
In the force control unit 120, a feedback loop for bringing the end point of the movable unit 21 of the robot 20 into contact with an object with a target value set as a target based on the sensor value input from the force sensor 25 is rotating. . The trajectory generation unit 124 generates a trajectory and a command value (here, a target angle) so that the input sensor value becomes a target value.

  Note that the robot control device 10 generates a trajectory and a command value so that the position and posture of the object estimated based on the image data are close to the target position and the target posture when performing visual servo control. In general, since the load of image processing is high, an interval (for example, every 30 milliseconds (msec)) for generating a command value by visual servo control is an interval (for example, 1 millisecond) at which the force control unit 120 outputs the command value. (Every (msec)).

  A command value (target angle) is input from the robot control device 10 to the drive control unit 200. The drive control unit 200 acquires the current angle based on the encoder value of each actuator provided in each joint 23 and calculates the difference (deviation angle) between the target angle and the current angle. Further, the drive control unit 200 calculates the moving speed of the arm 22 based on the deviation angle, and moves the movable unit 21 by the deviation angle corresponding to the calculated moving speed.

Next, robot control processing according to the present embodiment will be described.
FIG. 4 is a flowchart showing the robot control process according to the present embodiment.
In this example, it is assumed that the robot 20 is caused to perform an operation of fitting the first gear into the central axis A1. In this work, the robot controller 10 causes the movable unit 21 to grip the first gear, and initially the first gear is separated from the central axis A1 by a predetermined distance in a predetermined direction, and the first gear is controlled by force control. The position and orientation are controlled and fitted to the second gear.

(Step S101) The force control unit 120 causes the opening of the first object to approach one end of the second object. Thereafter, the process proceeds to step S102.
(Step S102) The force control unit 120 determines whether or not the planar portion of the first object has come into contact with one end of the second object. When it is determined that contact has been made (YES in step S102), the process proceeds to step S103. When it is determined that they are not in contact (NO in step S102), step S101 is repeated.

(Step S103) The force control unit 120 determines whether one end of the second object is inserted into the opening of the first object. When it determines with having inserted (step S103 YES), the force control part 120 is the 1st target object so that the direction of the central axis of a 1st target object may correspond with the direction of the central axis of a 2nd target object. Adjust the posture. Then, the force control unit 120 pushes the first object from one end to the other end, and ends the processing according to FIG. If it is determined that it is not inserted (NO in step S103), the process proceeds to step S104.
(Step S104) The force control unit 120 translates the first object so as to shift to a displacement point shifted by a predetermined offset amount in a predetermined offset direction from the initial contact point. Thereafter, the process proceeds to step S105.

(Step S <b> 105) The force control unit 120 moves the first object so that the contact point approaches the initial contact point from the displacement point while bringing the surface portion of the first object into contact with one end of the second object. Move. Thereafter, the process proceeds to step S106.
(Step S106) The force control unit 120 determines whether one end of the second object is inserted into the opening of the first object. If it is determined that it has been inserted (YES in step S106), the processing according to FIG. 4 is terminated. If it is determined that it is not inserted (NO in step S106), the process proceeds to step S107.

(Step S107) The force control unit 120 determines whether or not the contact point has reached the initial contact point from the above-described displacement point without inserting one end of the second object into the opening of the first object. judge. If it is determined that it has reached (YES in step S107), the process proceeds to step S108. If it is determined that it has not reached (NO in step S108), the process proceeds to step S105.
(Step S108) The force control unit 120 changes the offset direction, and resets the displacement point at a position shifted by a predetermined offset amount in the changed offset direction from the initial contact point. Thereafter, the process proceeds to step S104.

Next, an example of a search region used when moving the first object so that the contact point approaches the contact point from the displacement point will be described.
FIG. 5 is a diagram illustrating an example of a search area.
In FIG. 5, the search area is indicated by a broken line. This search area is a square defined based on the initial contact point C and the displacement point S1, that is, an area having a width equal to the offset amount d in a direction perpendicular to the line segment connecting the initial contact point C and the displacement point S1. It is. An arrow directed from the initial contact point C to the displacement point S1 is an arrow indicating a predetermined offset direction, and W and A indicate an opening of the first object and the first object, respectively. By setting the size of the search area based on the error described above, the force control unit 120 moves the first object so as to approach the initial contact point C from the displacement point S1 within the search area. Thereby, the position which may be a position of the 1st subject in which the field of the opening of the 1st subject is contained in the end of the 2nd subject is searched without omission. Further, by searching the position of the first object so as to approach the initial contact point C from the displacement point S1, the position can be efficiently searched as a whole. That is, when the process shown in FIG. 4 is repeated a plurality of times, it may not be possible to search earlier depending on the position of the initial contact point C at a certain time. However, as a whole, the search is performed earlier than when searching randomly. Means you can.

FIG. 6 is a diagram illustrating another example of the search area.
The position of the opening A of the first object may not be within the search area determined based on the displacement point S1 determined in the offset direction determined in advance from the initial contact point C. In that case, in step S107, it is determined that one end of the second object has not been inserted into the opening of the first object, and the contact point has reached the initial contact point C from the displacement point S1. In step S108, the offset direction is changed to a direction opposite to the previous offset direction, for example, and a new displacement point S2 is set. A square indicated by a broken line in FIG. 6 indicates a search area newly determined based on the initial contact point C and the displacement point S2. The force control unit 120 moves the first object so that the contact point approaches the initial contact point C from the displacement point S2 within the search region. Thereby, the contact point where the area | region of the opening part of a 1st target object is contained in the end of a 2nd target object is searched reliably.

Next, an example of a route (search route) used when moving the first object so that the contact point approaches the initial contact point from the displacement point within the search region will be described.
FIG. 7 is a diagram illustrating an example of a search route.
The search path shown in FIG. 7 is a zigzag path including the displacement point S1 and the initial contact point C. This path is formed by connecting a portion (orthogonal line segment) orthogonal to the line segment connecting the initial contact point C and the displacement point S1 and a portion connecting the start point of the adjacent orthogonal line segment from the end point of the one orthogonal line segment (oblique line). Line segment). In this example, the length of one orthogonal line segment is equal to the offset amount d. By setting the interval between the orthogonal lines or the diagonal lines to be smaller than the diameter of the opening of the first object, the search area is covered by this search path. This interval is, for example, the difference between the diameter of the opening of the first object and the diameter of one end of the second object. The starting point and ending point of this search path may be the initial contact point C and the displacement point S1, but may also be the vertices O1 and D1 of the search area as shown in FIG.

FIG. 8 is a diagram illustrating another example of the searched route.
The search route shown in FIG. 8 is a rectangular route including the displacement point S1 and the initial contact point C. This path is configured by repeating a portion (orthogonal line segment) orthogonal to the line segment connecting the initial contact point C and the displacement point S1, and a portion (parallel line segment) parallel to the initial contact point C and the displacement point S1. Is done. Also in this example, the length of one orthogonal line segment is equal to the offset amount d. As in the example shown in FIG. 7, the interval between the orthogonal lines is determined to be smaller than the diameter of the opening of the first object. The search path is configured by repeating the configuration in which the end point of one orthogonal line segment and the starting point of one parallel line segment are connected, and the end point of the parallel line segment is connected to the starting point of the adjacent orthogonal line segment. . The starting point and ending point of this search path may be the initial contact point C and the displacement point S1, but may also be the vertices O2 and D2 of the search area as shown in FIG.

FIG. 9 is a diagram showing still another example of the searched route.
The search path shown in FIG. 9 is a spiral path starting from the displacement point S1 and ending at the initial contact point C. This path is configured by periodically repeating a curve in which the length of the major axis orthogonal to the initial contact point C and the displacement point S1 is equal to the offset amount d. The interval per cycle is set to be smaller than the diameter of the opening of the first object. Thereby, the search area is covered.

FIG. 10 is a diagram showing still another example of the searched route.
The search path shown in FIG. 10 is a spiral path formed by a locus starting from the displacement point S1 and rotating around the displacement point S1 and having a radius increasing from the center as the rotation occurs. is there. The end point of this route is the initial contact point C as an end point, and the amount of increase in radius per round is set to an interval smaller than the diameter of the opening of the first object. Thereby, a substantially circular area is covered as a search area.

  The search route may have any shape as long as it covers the search region and is close to the initial contact point C from the displacement point S1. The search path is, for example, a sine curve passing through the displacement point S1 and the initial contact point C. The search route may include a portion away from the initial contact point C as a part thereof, as shown in the above-described example.

The configuration of the robot system 1 described above describes the features of the present embodiment, and is not limited to this. The robot control apparatus 10 may be configured with a computer.
FIG. 11 is a diagram illustrating another example of the functional configuration of the robot control apparatus 10 according to the present embodiment.
The robot control device 10 includes a CPU (Central Processing Unit) 11, a memory 12, an external storage device 13, a communication device 14, an input device 15, an output device 16, and an I / F (Interface) 17.
CPU11 performs the calculation which concerns on the process mentioned above. The memory 12 includes a ROM (Read Only Memory) that is a non-volatile storage device and a RAM (Random Access Memory) that is a volatile storage device. The communication device 14 communicates with the robot 20. The input device 15 is a device that accepts a user's operation and inputs an operation input signal corresponding to the accepted operation, such as a mouse, a keyboard, or the like. The output device 16 is a device that outputs image data so as to be visible, such as a display. The I / F 17 is connected to another device, and inputs or outputs data. For example, the I / F 17 inputs image data from the imaging device 30, for example.

  Each functional unit described above is realized, for example, by the CPU 11 reading and executing a predetermined program stored in the memory 12. The predetermined program may be installed in advance in the memory 12, for example, or may be downloaded from the network via the communication device 14 and installed or updated.

The robot control device 10 and the robot 20 may be configured separately from each other as described above, but the robot control device 10 may be configured as a robot 20 integrated with the robot 20. When configured integrally, the robot 20 may incorporate the robot control device 10.
The imaging device 30 may be separate from the robot control device 10 or the robot 20 as described above, but may be integrated.
In the present embodiment, a double-arm robot including two movable parts 21 is shown as an example of the robot 20, but a single-arm robot including one movable part 21 and three or more movable parts 21 are provided. It may be a robot. The robot 20 may be a scalar robot or a vertical articulated robot. Further, the robot 20 may include wheels and legs, for example, in order to enable movement.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.
The functional configuration of the robot system 1 described above is classified according to main processing contents in order to facilitate understanding of the configuration of the robot system 1. The present invention is not limited by the way of classification and names of the constituent elements. The configuration of the robot system 1 can be classified into more components depending on the processing content. Moreover, it can also classify | categorize so that one component may perform more processes. Further, the processing of each component may be executed by one hardware or may be executed by a plurality of hardware.
In addition, when visual servo control is not performed, or when image data is not used, at least one of the image acquisition unit 140 and the imaging device 30 may be omitted.

  Further, the functions and processing sharing of the robot control device 10 and the robot 20 are not limited to the illustrated example. For example, at least a part of the functions of the robot control device 10 may be included in the robot 20 and realized by the robot 20. Further, for example, at least a part of the functions of the robot 20 may be included in the robot control device 10 and realized by the robot control device 10.

  In addition, each processing unit in the above-described flowchart is divided according to main processing contents in order to facilitate understanding of the processing of the robot control apparatus 10. The present invention is not limited by the way of dividing the processing unit or the name. The processing of the robot control device 10 can be divided into more processing units according to the processing content. Moreover, it can also divide | segment so that one process unit may contain many processes.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiment. In addition, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 ... Robot system,
DESCRIPTION OF SYMBOLS 10 ... Robot control system, 11 ... CPU, 12 ... Memory, 13 ... External storage device,
14 ... Communication device, 15 ... Input device, 16 ... Output device, 17 ... I / F,
120 ... Force control unit, 122 ... Sensor information acquisition unit, 124 ... Trajectory generation unit,
140 ... an image acquisition unit,
20 ... Robot, 21 ... Movable part, 22 ... Arm, 23 ... Joint, 24 ... Link,
25 ... force sensor, 26 ... hand, 200 ... drive control unit,
30 ... Imaging device

Claims (8)

A robot that inserts an opening of a first object into a protrusion of a second object,
A force sensor;
A hand, and
The first object is gripped by the hand,
Bringing the opening of the first object closer to the protrusion of the second object;
robot.   The robot according to claim 1, wherein the second object is placed. When moving the opening of the first object with the second object as a target, the first object is in a predetermined direction from an initial contact point where the first object is in contact with the second object for the first time. A displacement point that is a displaced position is set, and the second contact point is such that a contact point that is a position where the first object contacts the second object approaches the initial contact point from the set displacement point. The robot according to claim 1, wherein the robot operates to move the first object while being in contact with the object.   The robot according to claim 3, wherein the distance between the initial contact point and the displacement point is a distance based on an error in the position of the first object.   The method according to claim 3 or 4, wherein the first object is moved so that the contact point is along a path covering a region having a predetermined width from a line segment connecting the displacement point and the initial contact point. The robot described.   When the second object is not detected in the region, a displacement point is reset to a position displaced from the initial contact point in a direction different from the predetermined direction, and the contact point is reset. The robot according to claim 5, wherein an operation of the robot is controlled so as to move the first object so as to approach the initial contact point from a point. A robot system comprising a robot and a robot control device that controls the operation of the robot,
The robot is a robot that inserts an opening of a first object into a protrusion of a second object,
A force sensor;
A hand, and
The first object is gripped by the hand,
The robot controller is
The robot system which controls operation | movement of the said robot so that the said opening part of a said 1st target object may be closely approached to the said projection part of a said 2nd target object. A force sensor;
A hand, and
The first object is gripped by the hand,
The operation of the robot inserting the opening of the first object into the protrusion of the second object,
A robot control apparatus that controls the opening of the first object to approach the protrusion of the second object.

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