JP2017039184A - robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot capable of placing an article at a predetermined position, regardless of a holding state of the article with a robot hand.SOLUTION: A robot comprises: a robot arm having a robot hand at a distal end; a holding member which forms a holding surface contacting an object to be held in the robot hand; a movable attachment part for freely attaching the holding member to the robot hand in an inclined state; and a control part, which corrects, when the robot hand holds the object to be held, a control amount of the robot arm for the robot arm to move with the object to be held to a predetermined position on the basis of an inclined angle of the holding member and a distribution of positions on the holding surface contacting the object to be held.SELECTED DRAWING: Figure 14

Description

  The present application relates to a robot.

  In recent years, robots are widely used in various fields. For example, various robots are widely used in production sites that mass-produce industrial products (see, for example, Patent Document 1). Moreover, robots that handle articles to be inspected are widely used in facilities that perform various tests and researches (for example, see Patent Document 2).

JP 2012-66368 A JP 2001-105374 A

  Some robots include a robot hand designed according to the shape of an article to be grasped, and some robots include a general-purpose robot hand capable of handling various articles. An example of a general-purpose robot hand that can handle various articles is one that opens and closes two fingers. If it is a general-purpose robot hand that can handle various items, it can support, for example, the cell production method for high-mix low-volume production and the mixed flow production method that assembles multiple types of products with different specifications on the same line. is there.

  However, in the case of a robot hand that grips an article with a plurality of fingers, if there are variations in the shape or arrangement of the article, the article may be missed or the article may be held in an inappropriate posture. If the assembly is performed in a state where the component is held in an inappropriate posture, the article may be assembled appropriately.

  Therefore, the present application discloses a robot that can place the article at a predetermined position regardless of the gripping state of the article in the robot hand.

  The present application discloses the following robot. That is, the robot disclosed in the present application includes a robot arm having a robot hand at the tip, a gripping member that forms a gripping surface on which the gripping target is in contact with the robot hand, and a movable attachment that tilts the gripping member to the robot hand. When the attachment unit and the robot hand grip the grip target, the robot arm holds the grip target based on an inclination angle of the grip member and a distribution of contact points of the grip target on the grip surface. And a control unit for correcting the control amount of the robot arm when moving to the position.

  With the robot described above, the article can be placed at a predetermined position regardless of the gripping state of the article in the robot hand.

FIG. 1 is a diagram illustrating an example of a robot according to the embodiment. FIG. 2 is a diagram illustrating an example of a robot hand. FIG. 3 is an enlarged view of the tip of the finger part. FIG. 4 is a diagram illustrating a sensor that detects the tilt angle of the gripping member. FIG. 5 is a diagram illustrating an arrangement state of the tactile sensor in the gripping member. FIG. 6 is a diagram illustrating an example of a state in which the robot hand grips a gripping target object. FIG. 7 is a diagram illustrating a distribution state of contact portions output by the tactile sensor when the robot hand grasps the upper end portion of the component. FIG. 8 is a diagram illustrating an example of parameters for calculating a relative posture of a part held by a robot hand with respect to a finger part. FIG. 9 is a configuration diagram illustrating an example of a control system for controlling the robot. FIG. 10 is a diagram showing a state of teaching. FIG. 11 is a diagram illustrating an example of a processing flow executed by the control system while teaching is performed. FIG. 12 is a diagram illustrating an example of processing contents executed by the control system while teaching is being performed. FIG. 13 is a diagram illustrating an example of a processing flow realized by the control system. FIG. 14 is an image diagram showing the contents of the tool coordinate correction processing. FIG. 15 is a view showing a first modification of the attachment mechanism for the gripping member. FIG. 16 is a diagram illustrating a second modification of the attachment mechanism for the gripping member. FIG. 17 is an explanatory diagram of the operation of the movable mounting portion according to the second modification.

  Hereinafter, embodiments will be described. The embodiment described below is merely an example, and the technical scope of the present disclosure is not limited to the following aspect.

  FIG. 1 is a diagram illustrating an example of a robot according to the embodiment. The robot R according to the embodiment is a so-called articulated robot, and is connected to the first arm 1C connected to the base 1A via the first joint 1B and to the tip of the first arm 1C via the second joint 1D. And a robot hand 2 provided at the tip of the second arm 1E via the third joint 1F.

  FIG. 2 is a diagram illustrating an example of the robot hand 2. As shown in FIG. 2, the robot hand 2 includes a pair of finger parts 2A for gripping the object to be gripped, and an actuator part 2B for moving the finger parts 2A and opening / closing between the finger parts 2A. The robot R is a robot that can be used at the production site of industrial products, and can be applied to, for example, work for assembling various parts to a product or work for handling an object to be inspected.

  FIG. 3 is an enlarged view of the tip of the finger part 2A. Each finger part 2A of the robot hand 2 has a gripping member 2D that forms a gripping surface 2C that comes into contact with the gripping object, and a gimbal mechanism 3 that attaches the gripping member 2D to the finger part 2A in a tiltable manner (referred to as “movable mounting part” in this application). Is an example). The grip member 2D is a rectangular parallelepiped member and forms a rectangular grip surface 2C. The gimbal mechanism 3 is a biaxial gimbal mechanism that can freely tilt the gripping member 2D in the roll direction and the pitch direction. That is, the gimbal mechanism 3 has a gimbal (hanging frame) 3B that is rotatably supported by the first rotating shaft 3A provided on the finger portion 2A. The gimbal 3B is provided with a second rotating shaft 3C that is orthogonal to the first rotating shaft 3A. The grip member 2D is rotatably supported by a second rotating shaft 3C provided on the gimbal 3B. Therefore, the gripping member 2D is attached to the finger portion 2A via the first rotating shaft 3A and the second rotating shaft 3C that are orthogonal to each other, and along the contact surface of the gripping object that contacts the gripping surface 2C. Can tilt.

FIG. 4 is a diagram illustrating a sensor that detects the tilt angle of the gripping member 2D. Each finger 2A has
Two inclination angle detection sensors 4R and 4Y for detecting the inclination angle of the gripping member 2D are provided. The tilt angle detection sensor 4R detects the tilt of the grip member 2D in the roll direction with respect to the finger portion 2A. The tilt angle detection sensor 4Y detects the tilt of the grip member 2D in the yaw direction with respect to the finger portion 2A. As an angle sensor applicable to the tilt angle detection sensors 4R and 4Y, in addition to a cantilever as shown in FIG. 4, for example, a potentiometer that detects a change in the angle of the rotating shaft by increasing or decreasing an electric resistance, a change in the angle of the rotating shaft And other various angle sensors.

  FIG. 5 is a diagram showing an arrangement state of the tactile sensor in the gripping member 2D. The grasping member 2D is provided with a tactile sensor 5 that can grasp the distribution of contact points of the grasped object that contacts the grasping surface 2C in two dimensions. As shown in FIG. 5, the tactile sensor 5 is disposed on the entire gripping surface 2C of the gripping member 2D. The tactile sensor 5 can capture in two dimensions the distribution of contact points of the gripping object that touches the gripping surface 2 </ b> C based on the presence or absence of contact of the gripping object at each of a number of touch points arranged vertically and horizontally.

  FIG. 6 is a diagram illustrating an example of a state in which the robot hand 2 grips a gripping target object. For example, the robot hand 2 can grip a substantially rectangular parallelepiped component 10 (which is an example of a “grip target” in the present application) 10 as illustrated in FIG. 6. For example, as shown in FIG. 6, the robot hand 2 can sandwich the upper end portion of the component 10 between a pair of finger portions 2 </ b> A. When the robot hand 2 sandwiches the upper end portion of the component 10 with a pair of finger portions 2A from a slightly oblique direction, the edge formed by the upper surface and the side surface of the component 10 is gripped as shown by the broken line portion in FIG. Crosses surface 2C.

  FIG. 7 is a diagram illustrating a distribution state of contact portions output by the tactile sensor 5 when the robot hand 2 grips the upper end portion of the component 10. For example, when the robot hand 2 grips the upper end portion of the component 10, the tactile sensor 5 outputs a distribution of contact locations as shown in FIG. 7 as a detection result. That is, when the robot hand 2 sandwiches the upper end portion of the component 10 between the pair of finger portions 2A from a slightly oblique direction, the side surface of the upper end portion of the component 10 comes into contact with the tactile sensor 5, and as shown in FIG. Most of the touch points except for the upper part of the frame detect the contact of the component 10. A boundary line between a region having a non-contact touch point remaining on the upper part of the tactile sensor 5 and a region having a touch point in contact that occupies most of the tactile sensor 5 is formed by an upper surface and a side surface of the component 10. Corresponds to the edge position. Therefore, if the boundary line between the region with the non-contact touch point of the touch sensor 5 and the region with the touch point in contact is estimated from the output of the touch sensor 5, the robot 10 holds the component 10 The relative inclination with the gripping member 2D can be specified.

  FIG. 8 is a diagram illustrating an example of parameters when calculating the relative posture of the part 10 held by the robot hand 2 with respect to the finger portion 2A. The relative posture of the part 10 held by the robot hand 2 with respect to the finger part 2A can be expressed by, for example, three parameters of the roll angle, the pitch angle, and the yaw angle of the part 10 with respect to the finger part 2A. Since the gripping member 2D can tilt along the contact surface of the component 10 that contacts the gripping surface 2C, the roll angle and pitch angle of the component 10 with respect to the finger portion 2A are obtained from the outputs of the tilt angle detection sensors 4R and 4Y. be able to. Further, the yaw angle of the component 10 with respect to the finger part 2 </ b> A is obtained by grasping the boundary line between the region with the non-contact touch point of the touch sensor 5 and the region with the touch point in contact estimated from the output of the touch sensor 5. It can be obtained from the inclination angle in the plane 2C.

FIG. 9 is a configuration diagram illustrating an example of a control system that controls the robot R. For example, as shown in FIG. 9, the control system 6 that controls the robot R is a robot controller 6A that is electrically connected to the drive mechanism of the robot arm 1 and a hand opening and closing that is electrically connected to the actuator unit 2B of the robot hand 2. A controller / driver 6B and a robot control computer 6C for transmitting various commands to the robot controller 6A and the hand opening / closing controller / driver 6B are provided. The control system 6 also has a target model information DB (database) 6D that stores information on the shapes of various gripping target objects such as the parts 10 and a tactile sense that processes signals output from sensors provided in the robot hand 2. A sensor signal processing circuit 6E and a tilt sensor signal circuit 6F, and a posture calculation computer 6G for calculating the posture of the component 10 based on information obtained from the tactile sensor signal processing circuit 6E and the tilt sensor signal circuit 6F are provided.

  The control system 6 is based on the world coordinate system, which is the coordinate system that serves as a reference for the positions of all objects such as the robot hand 2, the robot arm 1, and the component 10, and the hand coordinate system is used for the position and orientation of the robot hand 2. The tool coordinate system is used for the shape of the object to be grasped by the robot hand 2. The hand coordinate system is a coordinate system based on the robot hand 2. Therefore, the position and orientation of the hand coordinate system in the world coordinate system can be specified based on the information on the angles of the joints of the robot arm 1. The tool coordinate system is a coordinate system based on the grasped object. Therefore, the position and orientation of the tool coordinate system in the hand coordinate system can be specified based on information from each sensor (inclination angle detection sensors 4R, 4Y and tactile sensor 5) of the robot hand 2. If the position and orientation of the hand coordinate system in the world coordinate system are specified, and the position and orientation of the tool coordinate system in the hand coordinate system are specified, the position and orientation of the tool coordinate system in the world coordinate system can also be specified.

  Each of the robot control computer 6C and the posture calculation computer 6G is a general-purpose personal computer capable of executing various arithmetic processes by executing a computer program developed on a memory. If a computer having sufficient calculation capability and interface capability is used, the robot control computer 6C and the posture calculation computer 6G may be realized by one computer.

  In the robot R of the present embodiment, the pitch angle of the component 10 with respect to the robot hand 2 is calculated using the output of the tactile sensor 5, so teaching that causes the robot R to learn the operation content is performed as follows. It is desirable.

  FIG. 10 is a diagram showing a state of teaching. The operator 11 operates the teaching pendant 7 to move the robot arm 1 and causes the robot R to learn the control amount when handling the component 10. At this time, the operator 11 adjusts the position of the robot hand 2 with the robot arm 1 so that the robot R grips the component 10 in the state shown in FIG. That is, the operator 11 does not bring the component 10 into contact with the entire gripping surface 2C, but brings the component 10 into contact with the gripping surface 2C so that a part of the gripping surface 2C is not in contact. At this time, the worker 11 takes care that the component 10 is in contact with at least the center portion of the gripping surface 2C. When the component 10 is gripped with the component 10 in contact with the end portion of the gripping surface 2C, the posture of the gripping member 2D attached to the finger portion 2A via the gimbal mechanism 3 becomes unstable. This is because if the posture of the gripping member 2D is unstable, the relative posture of the component 10 with respect to the finger portion 2A cannot be calculated correctly.

  FIG. 11 is a diagram illustrating an example of a processing flow executed by the control system 6 while teaching is being performed. FIG. 12 is a diagram illustrating an example of processing contents executed by the control system 6 while teaching is being performed.

The control system 6 determines whether or not the tactile sensor 5 has sensed pressure while teaching is being performed (S101). When the control system 6 makes an affirmative determination in the process of step S101, it extracts the position of the edge of the component 10 that forms a boundary line between the region with the non-contact touch point and the region with the touch point in contact ( S102). After performing the process of step S102, the control system 6 uses the object model information D as information on the edge position extracted in the process of step S102.
Save to B6D (S103).

  The robot R can perform automatic assembly work of the parts 10 after teaching. Hereinafter, a processing flow realized by the control system 6 when the assembly work of the component 10 is performed will be described. FIG. 13 is a diagram illustrating an example of a processing flow realized by the control system 6.

  When the robot R receives an instruction from the controller or the host device, the control system 6 grips the component 10 (S201). That is, the control system 6 outputs the control amount of the operation content learned in teaching to the robot controller 6A to move the robot arm 1, and aligns the robot hand 2 at the tip of the robot arm 1 with the component 10. Then, the control system 6 outputs a command to the hand opening / closing controller / driver 6B, closes each finger 2A of the robot hand 2, and grips the component 10.

After executing the process of step S201, the control system 6 calculates the posture of the component 10 (S202). The posture R of the component 10 with respect to the robot hand 2 is calculated based on the following equation (1).

  Α shown in the above equation (1) is the roll angle of the component 10 with respect to the robot hand 2 and is a value detected by the tilt angle detection sensor 4R. Further, β shown in the above equation (1) is the yaw angle of the component 10 with respect to the robot hand 2 and is a value detected by the tilt angle detection sensor 4Y. Further, γ shown in the above formula (1) is the pitch angle of the component 10 with respect to the robot hand 2 and is a value obtained based on the output of the touch sensor 5 as described above.

  After executing the process of step S202, the control system 6 performs a tool coordinate correction process (S203). In other words, the control system 6 uses the orientation R in the tool matrix of the tip of the robot arm 1 based on the orientation R in the rotation matrix format of the part 10 calculated from the expression (1) in step S202. Correct the component data.

  FIG. 14 is an image diagram showing the contents of the tool coordinate correction processing. For example, it is assumed that the position of the component 10 in the tool coordinate system is represented by X, Y, and Z, and the posture (inclination) of the component 10 is represented by Rx, Ry, and Rz. Here, the position and orientation of the part 10 in the tool coordinate system stored in the object model information DB 6D at the time of teaching are, for example, (X, Y, Z, Rx, Ry, Rz) = (0, 0, 100). , 0, 0, 0). On the other hand, the position and orientation of the component 10 gripped in the process of step S201 are, for example, (X, Y, Z, Rx, Ry, Rz) = (0, 0, 100, 2.3, 1.2). , 5.5). As described above, when the component 10 is gripped in a slightly different state from that at the time of teaching, the control system 6 uses the tool coordinates using the posture R calculated based on the outputs of the tilt angle detection sensors 4R and 4Y and the tactile sensor 5. The corrected position and orientation values (X, Y, Z, Rx, Ry, Rz) = (0, 0, 100, 2.3, 1.2, 5.5) of the component 10 are performed. ) Is derived.

  After executing the process of step S203, the control system 6 moves the component 10 to a predetermined position (S204). The predetermined position is a movement destination of the component 10 to be moved by the robot R, for example, an assembly position of the component to be assembled by the robot R in an industrial product production line. Based on the corrected tool coordinate data, the control system 6 corrects the control amount of the robot arm 1 when the component 10 is moved to a predetermined position whose coordinates are indicated by the world coordinate system. The control system 6 outputs the corrected control amount to the robot controller 6A, moves the robot arm 1, and aligns the component 10 gripped by the robot hand 2 at the tip of the robot arm 1 to a predetermined position. Then, the control system 6 outputs a command to the hand open / close controller / driver 6B, opens each finger 2A of the robot hand 2, and releases the component 10.

  After executing the process of step S204, the control system 6 outputs an appropriate control amount to the robot controller 6A, moves the robot arm 1, and moves the robot hand 2 away from a predetermined position (S205).

  Since the robot R according to the present embodiment can handle various articles by opening and closing the two fingers 2A, for example, a cell production method for high-mix low-volume production, or a plurality of different specifications on the same line It is possible to correspond to the mixed flow production method of assembling various kinds of products. The robot R of the present embodiment grips the article with the two fingers 2A, but the control amount of the robot arm 1 is corrected according to the gripping state of the article being gripped. The article can be placed at a predetermined position regardless of the gripping state. Since the robot R of the present embodiment can place the article at a predetermined position regardless of the gripping state of the article, the assembly of the article due to the article being gripped in an inappropriate posture by the robot hand 2 Can be suppressed.

  By the way, the gripping member 2D may be attached to the finger portion 2A through the following mechanism, for example.

  FIG. 15 is a view showing a first modification of the attachment mechanism of the gripping member 2D. FIG. 15A is a view showing the tip of the finger part 2A according to the first modification, and FIG. 15B is a view showing the internal structure of the finger part 2A according to the first modification. The gripping member 2D has, for example, a ball joint 8a2 provided at the tip of a protruding portion 8a1 that protrudes from the gripping member 2D toward the back side of the gripping surface 2C, like a movable mounting portion 8a shown in FIG. It may be attached to the finger portion 2A via an attachment mechanism that fits into the recess 8a3 of the finger portion 2A and supports the gripping member 2D so as to be rotatable about the ball joint 8a2.

  The movable mounting portion 8a of the first modified example has a structure in which the ball joint 8a2 is fitted in the recess 8a3 of the finger portion 2A and can rotate around a normal line orthogonal to the gripping surface 2C of the gripping member 2D. The gripping member 2D is fitted into the opening 8a4 of the finger portion 2A that is opened with a size such that there is a slight gap from the outer edge of the gripping surface 2C. By fitting the gripping member 2D into the opening 8a4, the rotation of the gripping member 2D around the normal line orthogonal to the gripping surface 2C is restricted.

Further, the movable mounting portion 8a of the first modification has a structure in which the ball joint 8a2 is fitted in the recess 8a3 of the finger portion 2A, and the gripping member 2D can hang down from the ball joint 8a2 due to gravity. A preventing spring 8a5 is inserted between the gripping member 2D and the finger portion 2A. The spring 8a5 is inserted between the gripping member 2D and the finger part 2A, so that the gripping member 2D can be tilted following the gripped object to be touched and hangs down when there is no contact of the touched object. Is suppressed by the elastic force of the spring 8a5, and the posture is maintained. The movable mounting portion 8a according to the first modification realizes a mounting mechanism with two degrees of freedom that allows the gripping member 2D to be tilted in the roll direction and the pitch direction around the ball joint 8a2.

  FIG. 16 is a view showing a second modification of the attachment mechanism for the gripping member 2D. The gripping member 2D includes, for example, four rod-shaped rods 8b6 each connected to four ball joints 8b2 provided on the back side of the gripping surface 2C of the gripping member 2D, like a movable mounting portion 8b shown in FIG. The finger portion 2A is provided with an attachment mechanism having a cylinder 8b7 through which each rod 8b6 is inserted and four linear motion joints 8b8 each slidably supporting each cylinder 8b7 in a direction perpendicular to the longitudinal direction of the cylinder 8b7. It may be attached.

  FIG. 17 is an operation explanatory diagram of the movable mounting portion 8b according to the second modification. In the movable mounting portion 8b according to the second modified example, when the gripping object comes into contact with the gripping member 2D, the rod 8b6 inserted through each cylinder 8b7 and the linear motion joint 8b8 move according to the inclination of the gripping member 2D. The movable attachment portion 8b according to the second modification realizes an attachment mechanism having at least two degrees of freedom that can tilt the gripping member 2D in the roll direction and the pitch direction. In addition, since the movable attachment part 8b which concerns on a 2nd modification can also push in the holding member 2D whole on the opposite side of the holding surface 2C, it implement | achieves the attachment mechanism of 3 degrees of freedom as a whole.

  Note that the gimbal mechanism 3 according to the embodiment and the movable mounting portion 8b according to the second modified example have no gripping object in contact with the gripping member 2D, similarly to the movable mounting portion 8a according to the first modified example. A spring, rubber, sponge, or other various elastic bodies that prevent the gripping member 2D from tilting may be inserted between the gripping member 2D and the finger portion 2A.

  Further, the gripping member 2D is attached to the finger portion 2A via an attachment mechanism such as the gimbal mechanism 3 of the above embodiment, the movable attachment portion 8a of the first modification, or the movable attachment portion 8b of the second modification. It is not limited. The gripping member 2D may be attached to the finger portion 2A via any attachment mechanism that can tilt the gripping surface 2C following the outer shape of the gripping target.

··· Robot: 1 ·· Robot arm: 1A ·· Base: 1B ·· First joint: 1C ·· First arm: 1D ·· Second joint: 1E ·· Second arm: 1F ·· Third joint : 2. Robot hand: 2A ... Finger part: 2B Actuator part: 2C ... Grip surface: 2D ... Grip member: 3 ... Gimbal mechanism: 3A ... First rotation axis: 3B ... Gimbal : 3C ··· Second rotation axis: 4R, 4Y · · Inclination angle detection sensor: 5 · · Tactile sensor: 6 · · Control system: 6A · · Robot controller: 6B · · Controller for hand opening and closing · Driver: 6C · -Robot control computer: 6D-Object model information DB: 6E-Tactile sensor signal processing circuit: 6F-Tilt sensor signal circuit: 6G-Orientation calculation computer: 7-Teaching pendant: 8a- Movable mounting part: 8a1・ Projection: 8a2, 8b2 ・ ・ Ball joint: 8a3 ・ ・ Dimple: 8a4 ・ ・ Opening: 8b5 ・ ・ Spring: 8b6 ・ ・ Rod: 8b7 ・ ・ Cylinder: 8b8 ・ ・ Linear joint: 10 ・ ・ Parts : 11..Worker

Claims (5)

A robot arm having a robot hand at the tip;
A gripping member that forms a gripping surface in contact with the gripping object in the robot hand;
A movable mounting portion for tilting the gripping member to the robot hand;
When the robot hand grips the gripping object, the robot arm moves the gripping object to a predetermined position based on the inclination angle of the gripping member and the distribution of contact points of the gripping object on the gripping surface. A control unit that corrects a control amount of the robot arm when performing the operation. When the control unit automatically moves the gripping object to the predetermined position, the control unit learns the control amount of the robot arm learned in teaching performed on the robot, and determines the gripping target in teaching. Correct according to the difference between the distribution of the contact points of the object and the distribution of the contact points of the gripping object when moving automatically,
The robot according to claim 1. When the robot hand grips the gripping object in a state where the edge of the gripping object is located within the surface of the gripping surface, the control unit is configured to determine an inclination angle of the gripping member and the gripping target object on the gripping surface. Correcting the control amount of the robot arm when moving the gripping object to a predetermined position by the robot arm based on the inclination angle of the edge estimated from the distribution of contact points of
The robot according to claim 1 or 2. A touch sensor is provided on the gripping surface,
When the robot hand grips the gripping object, the control unit uses the robot arm to perform the gripping target based on a tilt angle of the gripping member and a distribution of contact points of the gripping object obtained from the tactile sensor. Correcting the control amount of the robot arm when moving an object to a predetermined position;
The robot according to any one of claims 1 to 3. The movable mounting portion has a biaxial gimbal mechanism that can freely tilt the gripping surface.
The robot according to any one of claims 1 to 4.

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