JP2016221646A - Robot and robot system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for operating an object with appropriate operation force taking supporting force into account even after the object is supported.SOLUTION: A robot comprises: a manipulator; a force detector detecting force applied to the manipulator; an actuator driving the manipulator; and an encoder detecting displacement of the manipulator. When a first object is brought into contact with a second object by the first object being held and moved by the manipulator, the robot causes a vertical direction component of operation force of the manipulator with respect to the first object to be less in comparison with the vertical direction component prior to contact of the first object therewith according to supporting force of the second object with respect to the first object.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a robot and a robot system.

In recent years, in the field of robots, impedance control for controlling an operation position according to a force applied to a manipulator has been used. Here, the operation position is a position as a control target derived based on a target force in active impedance control and a force actually acting on the manipulator. Gravity acting on the manipulator and the workpiece varies depending on the posture of the manipulator and the workpiece. In order to accurately control the impedance of the manipulator under the influence of gravity, a technique for gravity compensation is known (for example, Patent Document 1).

JP 2009-23047 A

However, when the technique disclosed in Patent Document 1 is applied to, for example, a fitting process between workpieces, one workpiece is in a state of supporting the other workpiece after the workpieces contact each other.
There is a problem that the mating process fails because the force compensated for gravity before mating acts on the workpiece even after mating.

The present invention was created to solve such problems, and provides a technique for operating an object with an appropriate operation force in consideration of the support force even after the object is supported. For the purpose.

A robot for achieving the object is a robot comprising a manipulator, a force detector that detects a force acting on the manipulator, an actuator that drives the manipulator, and an encoder that detects a displacement of the manipulator.
When the first object comes into contact with the second object by holding and moving the first object, the manipulator moves the manipulator according to the supporting force of the second object with respect to the first object. The vertical component of the operating force on the first object is made smaller than before the contact.

By adopting this configuration, before and after the supporting force of the second object is added to the force acting on the first object, the manipulator's operating force on the first object is small according to the supporting force of the second object. Therefore, the first object can be operated with an appropriate operation force in consideration of the support force. Here, the contact force that acts on the first object from the second object by the contact between the first object and the second object, unless the manipulator grips the first object and pushes it down vertically,
Less than gravity acting on the first object. If the center of gravity of the first object and the contact point between the first object and the second object are not aligned on the vertical line, the supporting force acting on the first object from the second object is the first object. It is less than gravity acting on things. An operation that is appropriately gravity compensated by reducing the vertical component of the operating force of the manipulator on the first object below the gravity acting on the second object in accordance with the supporting force of the second object on the first object. The first object can be operated with force.

Note that the function of each means described in the claims is realized by hardware resources whose function is specified by the configuration itself, hardware resources whose function is specified by a program, or a combination thereof. The functions of these means are not limited to those realized by hardware resources that are physically independent of each other.

It is a perspective view of a robot system. It is a block diagram of a robot system. It is a side view of an end effector. It is a schematic diagram which shows the fitting operation | work using a robot system. It is a schematic diagram which shows the fitting operation | work using a robot system. It is a schematic diagram which shows the grinding | polishing operation | work using a robot system. It is a schematic diagram which shows the screw fastening operation | work using a robot system.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.

(1) Configuration of Robot System As shown in FIG. 1, a robot system as a first embodiment of the present invention includes a robot 1,
An end effector 2, a control device 3, and a teaching terminal 4 (teaching pendant) are provided. The control device 3 is a configuration example of the robot control device of the present invention. The control device 3 is communicably connected to the robot 1 via a cable (not shown). The components of the control device 3 may be provided in the robot 1. The control device 3 includes a power supply unit 31 that supplies driving power to the robot 1 and a control unit 32 for controlling the robot 1. The control device 3 and the teaching terminal 4 are connected by a cable or wireless communication. The teaching terminal 4 may be a dedicated computer or a general-purpose computer in which a program for the robot 1 is installed. For example, a teaching pendant 5 that is a dedicated device for teaching the robot 1 may be used instead of the teaching device 4. Furthermore, the control device 3 and the teaching terminal 4 may be provided with separate housings as shown in FIG. 1 or may be configured integrally.

The robot 1 is a single-arm robot that is used with various end effectors 2 attached to the arm A. The arm A includes six joints J1 to J6. Six arm members A1 to A6 are connected by joints J1 to J6. Joints J2, J3, and J5 are bending joints, and joint J1
, J4 and J6 are torsional joints. Various end effectors 2 for gripping and processing the workpiece are mounted on the joint J6. A predetermined position on the rotation axis of the joint J6 at the tip is represented as a tool center point (TCP). The position of TCP is various end effectors 2
It becomes the reference of the position of.

The joint J6 is provided with a force sensor FS. The force sensor FS is a 6-axis force detector. The force sensor FS detects the magnitude of the force parallel to the three detection axes orthogonal to each other in the sensor coordinate system, which is a unique coordinate system, and the magnitude of the torque around the three detection axes. The force sensor FS is a configuration example of the force detector of the present invention, but a force sensor as a force detector may be provided in any one or more of the joints J1 to J5 other than the joint J6.

When the coordinate system that defines the space in which the robot 1 is installed is referred to as a robot coordinate system, the robot coordinate system is a Z-axis with the X axis and the Y axis orthogonal to each other on the horizontal plane and the vertical direction as the positive direction.
A three-dimensional Cartesian coordinate system defined by an axis. The negative direction on the Z-axis generally coincides with the direction of gravity. The rotation angle around the X axis is represented by RX, the rotation angle around the Y axis is represented by RY, and Z
The rotation angle around the axis is represented by RZ. An arbitrary position in the three-dimensional space can be expressed by a position in the X, Y, and Z directions, and an arbitrary posture in the three-dimensional space can be expressed by a rotation angle in the RX, RY, and RZ directions. Hereinafter, when it is described as a position, it can also mean a posture. In addition, when expressed as force, it can also mean torque. The controller 3 controls the position of the TCP in the robot coordinate system by driving the arm A.

FIG. 2 is a block diagram of the robot system. The control unit 32 is a computer in which a control program for controlling the robot 1 is installed. The control unit 32 includes a processor, a RAM, and a ROM, and these hardware resources cooperate with the control program.

In addition to the configuration shown in FIG. 1, the robot 1 includes motors M1 to M1 as actuators.
M6 and encoders E1 to E6 as sensors are provided. Controlling the arm A means controlling the motors M1 to M6. Motors M1-M6 and encoder E
1 to E6 are provided corresponding to each of the joints J1 to J6, and the encoder E1
-E6 detects the rotation angle of the motors M1-M6. The control device 3 includes motors M1 to M6.
The correspondence U1 between the combination of the rotation angles and the TCP position in the robot coordinate system is stored. Further, the control unit 3 stores the target position S _t and the target force f _St as a command for each step of the work robot 1 performs. Command to determine the target position S _t and the target force f _St is set by teaching for each step of the work robot 1 performs.

The control device 3 controls the arm A so that the set target position and target force are realized by TCP.
To control. The target force is a force that should be detected by the force sensor FS in accordance with the operation of the arm A. Here, the letter S is the direction of the axis defining the robot coordinate system (X, Y, Z, RX, RY,
RZ) represents any one direction. S represents the position in the S direction. For example, in the case of S = X, X-direction component of the position specified in the robot coordinate system is denoted as S _t = X _t, X-direction component of the desired force is denoted as f _St = f _Xt.

The controller 3 acquires the rotation angle D _a motor M1-M6, based on the correspondence relationship U1, the rotation angle D _a of TCP in the robot coordinate system position S (X, Y, Z, RX,
RY, RZ). Based on the position S of the TCP and the detection value of the force sensor FS, the control device 3 specifies the acting force f _S actually acting on the force sensor FS in the robot coordinate system. The point of action of the acting force f _s is defined as the origin O separately from TCP. Origin O
Corresponds to the point that the force sensor FS detects force. The control device 3 stores a correspondence U2 that defines the direction of the detection axis in the sensor coordinate system of the force sensor FS for each position S of the TCP in the robot coordinate system. Therefore, the control device 3 can specify the acting force f _S in the robot coordinate system based on the TCP position S and the correspondence U2 in the robot coordinate system. Further, the torque acting on the robot can be calculated from the acting force f _S and the distance from the tool contact point (contact point between the end effector 2 and the workpiece) to the force sensor FS. Identified.

The control device 3 performs gravity compensation for the acting force f _S. Gravity compensation is to remove components of force and torque caused by gravity from the acting force f _S. The acting force f _S subjected to gravity compensation can be regarded as a force other than gravity acting on the end effector 2.

In the impedance control of this embodiment, the virtual mechanical impedance is changed to motors M1 to M6.
Active impedance control realized by The control device 3 applies such impedance control in a contact state process in which the end effector 2 receives a force from the object (workpiece), such as work fitting work and polishing work. In the impedance control, the target force is substituted into an equation of motion described later to derive the rotation angles of the motors M1 to M6. The signal for controlling the motors M1 to M6 by the control device 3 is a PWM (Pulse Width Modulation) modulated signal. A mode in which the rotation angle is derived from the target force based on the equation of motion to control the motors M1 to M6 is referred to as a force control mode. The control device 3 controls the motors M <b> 1 to M <b> 6 at a rotation angle derived from the target position by linear calculation in a non-contact state in which the end effector 2 does not receive force from the workpiece. A mode in which the motors M1 to M6 are controlled at a rotation angle derived from the target position by linear calculation is referred to as a position control mode. The control device 3 integrates the rotation angle derived from the target position by linear calculation and the rotation angle derived by substituting the target force into the equation of motion, for example, by linear coupling, and controls the motors M1 to M6 with the integrated rotation angle. The robot 1 is also controlled in the hybrid mode. The control device 3 can autonomously switch between the position control mode, the force control mode, and the hybrid mode based on the detection values of the force sensor FS or the encoders E1 to R6, or the position control mode and the force control according to the command. You can also switch between mode and hybrid mode. With the above configuration, the control device 3
Can drive the arm 10 so that the end effector 2 assumes a target posture at the target position, and a target force and moment act on the end effector 2.

The control device 3 specifies the force-derived correction amount ΔS by substituting the target force f _St and the acting force f _S into the equation of motion for impedance control. The force-derived correction amount ΔS is defined as T in order to eliminate the force deviation Δf _S (t) from the target force f _St when the TCP receives mechanical impedance.
This means the size of the position S where the CP should move. The following equation (1) is an equation of motion for impedance control.

The left side of the equation (1) is a first term obtained by multiplying the second-order differential value of the TCP position S by the virtual inertia coefficient m, a second term obtained by multiplying the differential value of the TCP position S by the virtual viscosity coefficient d, And a third term obtained by multiplying the position S of the TCP by the virtual elastic coefficient k. The right side of the equation (1) is constituted by a force deviation Δf _S (t) obtained by subtracting the actual force f from the target force f _St. The differentiation in the equation (1) means differentiation with time. In the step of the robot 1 performs, to some cases a constant value is set as the target force f _St, there is a case where a function of time as the target force f _St is set.

The virtual inertia coefficient m means the mass that the TCP virtually has, the virtual viscosity coefficient d means the viscous resistance that the TCP virtually receives, and the virtual elastic coefficient k is the spring constant of the elastic force that the TCP virtually receives. means. Each coefficient m, d, k may be set to a different value for each direction, or may be set to a common value regardless of the direction.

Then, the control unit 3, based on the correspondence relationship U1, the operation position in the direction of each axis defining a robot coordinate system, and converts the target angle D _t is a rotation angle of the target of the motors M1-M6. Then, the control unit 3, by subtracting the output D _a of the encoder E1~E6 from the target angle D _t is a rotation angle of the real motor M1-M6, the drive position deviation D _e (= D _t -D _a
) Is calculated. Then, the control device 3, a value obtained by multiplying the position control gain K _p to the driving position deviation D _e, the driving speed deviation which is a difference between the driving speed is the time differential value of the actual rotational angle D _a, the speed control The control amount D _c is derived by adding the value multiplied by the gain K _v . Note that the position control gain K _p and the speed control gain K _v may include not only a proportional component but also a control gain related to a differential component and an integral component. The control amount D _c is specified for each of the motors M1 to M6. With the configuration described above, the control device 3 can control the arm A in the force control mode based on the target force f _St.

In the hybrid mode, the control device 3, the target position S _t, identifies the operating position by adding a force from the correction amount ΔS (S _t + ΔS).

The teaching terminal 4, the teaching program for setting the target position S _t and the target force f _St is installed in the control unit 3. The teaching terminal 4 includes a display 43, a processor, and an R
AM and ROM are provided, and these hardware resources cooperate with the teaching program. Thus, as shown in FIG. 2, the teaching terminal 4 outputs to the control unit 3 generates a command that specifies a target force f _St and the target position S _t in accordance with the operator's operation.

(2) First Example FIG. 3 shows a gripper 20 as a specific example of the end effector 2. Gripper 2
0 includes two or more chucks 23 and a drive unit 22. The driving unit 22 is an actuator for approaching and separating two or more chucks 23, and is controlled by a control signal from the control device 3. The tip of the chuck 23 faces the tip of the arm. In this embodiment, the gripper 20 and the arm A are configuration examples of the manipulator according to the present invention.

Next, referring to FIG. 4, the gripper 20 is used to replace the first object W11 with the second object W2.
A method for setting the operation force of the robot 1 will be described in detail by taking as an example a fitting operation of inserting into one hole H. It is assumed that the central axis of the hole H is horizontal.

First, as shown in FIG. 4A, the control device 3 moves the hole H of the second object W21 close to the hole H of the second object W21 in the position control mode with the gripper 20 holding the central axis of the insertion portion of the first object W11 horizontally. Stop. In the stop state, the rotation axis of the joint J6 (not shown) is assumed to be horizontal. In such a stopped state, since the gravity g acting on the masses of the gripper 20 and the first object W11 acts as a torque on the origin O of the force sensor FS, the detected value corresponding to this torque is set to the control device 3. Is obtained from the force sensor FS.

Next, the control device 3 performs gravity compensation. Specifically, the offset is set so that the acting force f _s derived based on the detection value of the force sensor FS in the stop state becomes zero.

Next, the control device 3 translates the first object W11 in the horizontal direction of the arrow D shown in FIG. 4A, and brings the first object W11 into contact with the second object W21 and stops it. In this step, the control device 3 may control the arm A in the force control mode or may control the arm A in the hybrid mode. When the first object W11 contacts the second object W21, the first object W11.
The drag fw _z acts on the second object W21. The control device 3 has a predetermined drag f
The arm A is controlled in the force control mode or the hybrid mode with w _z as a target force. The stop condition for this step is acting force f _s = fw _z . That is, in this case, the force sensor FS as a force detector detects that the first object W11 has contacted the second object W21.

In a state where the first object W11 is in contact with the surface of the second object W21, the first object W11 and the gripper 20 are supported by the second object W21 by the vertically upward frictional force _fy according to the drag force. . In the process from the translation of the first object W11 to the contact with the second object W21, the Y component of the target force is zero. Therefore, the impedance control is performed by maintaining the Y component of the target force at zero after the contact. If it continues, the control apparatus 3 will try to cancel the frictional force fw _y , and the 1st target object W
11 is translated vertically upward.

Therefore, when detecting that the first object W11 is in contact with the surface of the second object W21, the control device 3 changes the target force by the support force-derived correction amount described below. Since the gripping state of the first object W11 by the gripper 20 is known and the shape of the first object W11 is also known, the force sensor FS is detected from the contact point between the first object W11 and the second object W21. The distance L to the origin O is also known. The position of the center of gravity G when the gripper 20 and the first object W11 are regarded as independent structures is also known. Accordingly, the internal force ratio l ₂ / L by the center of gravity G of the line segment connecting the contact point with the second object W21 and the origin O of the force sensor FS is the frictional force fw _y between the first object W11 and the gripper 20. Consider the contribution rate to support. Then, the target force fw _z in the horizontal direction in the steps up to contacting the first object W11 by translating the second object W21 are also known. Moreover, the static friction coefficient of the 1st target object W11 and the 2nd target object W21 is also known. Therefore, the frictional force fw _y corresponding to the drag force equal to the target force fw _z is obtained by calculation. Therefore, in the present embodiment, the support force-derived correction amount Δf _g is defined by the following equation (2) to control the control device 3 in advance.
Remember it.
Δf _g = fw _y × l ₂ / L (2)

Next, the control device 3 controls the arm A in the force control mode or the hybrid mode in which the target force having the vertical component including the support force-derived correction amount defined in this way is included, and thereby the second object W21. The position of the hole H is found by translating the first object W11 along the surface. When the first object W11 is translated along the surface of the second object W21 while pressing the first object W11 against the second object W21, the second object is located at the position where the first object W11 fits into the hole H. drag fw _z decreases receive from the object W21. By setting an appropriate horizontal component of the target force using this phenomenon, the tip of the first object W11 can be inserted into the entry hole H as shown in FIG. 4C. The depth at which the tip of the first object W11 is inserted into the hole H in this step can be set by the horizontal component of the target force.

When the tip of the first object W11 is inserted into the entry hole H, the first object W11 and the gripper 20 are supported by the drag fw _y received from the inner wall surface of the hole H. Second object W2
The supporting force (vertically upward) acting on the first object W11 from 1 increases as the tip of the first object W11 is inserted into the entry hole H.

Therefore, the control device 3 changes the support force-derived correction amount according to the increased support force. Specifically, for example, the internal ratio l ₂ / L by the centroid G of the line segment connecting the action point of the drag force f _y received from the inner wall surface of the hole H and the origin O of the force sensor FS is set to the second object W21. Support force is the first object W1
1 and the contribution ratio supporting the gripper 20, and the second support force-derived correction amount Δf _g is expressed by the above formula (
2) and stored in the control device 3 in advance.

Next, the control device 3 determines in advance by controlling the arm A in a force control mode or a hybrid mode in which a target force having a vertical component including the second support force-derived correction amount thus defined is included. The first object W11 is inserted into the hole H to the depth to be kept. In this step, if the impedance of arm A is controlled without considering the support force of the second object W21, the control device 3 tries to cancel the support force (vertically upward) of the second object W21. It tries to translate W11 vertically upward. As a result, the first object W11 is pressed against the upper surface of the hole H and the frictional force between the first object W11 and the second object W21 increases, so that the first object W11 is drilled to a predetermined depth. Cannot insert into H. In the present embodiment, since the first object W11 is inserted into the hole H by impedance control in which a target force having a vertical component that includes the second support force-derived correction amount is set, the first object W11 is accurately set to a predetermined depth. One object W11
Can be inserted into the hole H.

(3) Second Embodiment FIG. 5 is a schematic view for explaining a second embodiment of the present invention. In the second embodiment, the contact between the first object W11 and the second object W21 is detected based on the detection values of the encoders E1 to E6 in the step of translating the first object W11 in the direction D that is neither horizontal nor vertical. Then, after the contact, the impedance control including the support force-derived correction amount is executed. Details will be described below.

As shown in FIG. 5A, the gripper 20 holds the first object W11 tilted with respect to the horizontal plane, and closes the hole H of the second object W21 in the position control mode to stop it. In the stop state, the rotation axis of the joint J6 (not shown) is inclined by a predetermined angle with respect to the horizontal plane. In the stop state, the distance from the tip of the first object W11 to the surface of the second object W21 is known.
Next, the control device sets an offset so that the acting force f _s becomes zero in the stopped state, that is, performs gravity compensation.

Next, the control device 3 translates the first object W11 in the position control mode in the direction of the arrow D shown in FIG. 5A and moves the first object W11 into the hole H of the second object W21 as shown in FIG. 5B. Stop by touching the edge. At the start of this process, from the front end of the first object W11 derived from the actual distance from the front end of the first object W11 to the surface of the second object W21 and the detection values of the encoders E1 to E6. An error is included between the distance to the surface of the second object W21. Therefore, in this step, the first object W11 is derived from the tip of the first object W11 derived based on the detection values of the encoders E1 to E6 so that the first object W11 is surely brought into contact with the edge of the hole H of the second object W21. The target position is set by adding an error equivalent to the distance to the surface of the two objects W21. Since the stop condition of this process is the target position, the encoders E1 to E6 are connected to the first object W1.
It has detected that 1 contacted the 2nd target object W21. When the first object W11 comes into contact with the second object W21, the first object W11 and the gripper 20 are supported by the drag fw received from the edge of the hole H of the second object W21.

Next, the control device 3 determines that the edge of the hole H of the second object W21 is the first object W11 and the gripper 20.
Is set to a target force having a vertical component including a support force-derived correction amount corresponding to a vertically upward drag fw that supports the. The amount of correction derived from the supporting force according to the drag force fw is from the edge of the hole H to the force sensor F.
The ratio of the horizontal distance l ₁ from the center of gravity G of the first object W11 to the horizontal distance L to the origin O of S and the origin O of the force sensor FS is the ratio of the support force of the second object W21 to the first object W11. It can be regarded as a contribution rate for supporting the gripper 20 and calculated in advance by the above equation (2).

Next, the control device 3 controls the arm A in the force control mode or the hybrid mode in which the target force having the vertical component including the support force-derived correction amount is set, thereby the first object W11.
Is rotated around the contact point with the second object W21, and the posture of the first object W11 is made to follow the axial direction of the hole H as shown in FIG. If the arm A is impedance controlled without considering the support force of the second object W21 in this step, the control device 3 tries to cancel the support force (vertically upward) of the second object W21, and the first object W11. Will be translated vertically upward.

Next, similarly to the first embodiment, the control device 3 controls the arm A in the force control mode or the hybrid mode to insert the first object W11 into the hole H to a predetermined depth.

(4) Third Embodiment FIG. 6 is a schematic diagram for explaining a third embodiment of the present invention. In the third embodiment, a sander 25 for polishing an object is mounted as an end effector as shown in FIG. 6A.
In a state where the sander 25 is pressed against the object W22, the sander 25 is supported by the frictional force fw _y acting between the object W22 and the sander 25 as shown in FIG. 6B. Therefore, in the step of polishing the object W22 with the sander 25, the frictional force fw _y is the same as in the first embodiment.
The arm A may be controlled in a force control mode or a hybrid mode in which a target force having a Y component that includes the correction amount derived from the support force calculated by the above equation (2) is calculated. . In the present embodiment, the arm A is a configuration example of the manipulator according to the present invention, the sander 25 is a configuration example of the first target object, and the target object W22 is a configuration example of the second target object.

(5) Fourth Embodiment FIG. 7 is a schematic diagram for explaining a fourth embodiment of the present invention. In the fourth embodiment, the driver 28 for rotating the screw W13 as the first object is an end effector as shown in FIG.
Mounted as shown in A. The driver 28 incorporates a suction device (not shown) that sucks air from the tip. 7B, the screw W13 is attracted to the tip of the driver 28 and translated in the horizontal direction of the arrow D, and the tip of the screw W13 is the edge of the screw hole SH of the second object W23 as shown in FIG. 7C. The screw W13 and the screwdriver 28 are connected to the second object W23.
It will be in the state supported by the drag fw _y received from the edge of the screw hole SH. Here, unlike the first and second embodiments, the coupling force between the screw W13 as the first object and the driver 28 as the second object is weak. Therefore, in the present embodiment, not the idea that the drag force _fy received from the edge of the screw hole SH of the second object W23 contributes as a support force that supports the entire screw W13 and the driver 28, but the screw hole of the second object W23. The correction amount derived from the support force may be calculated based on the idea that the drag fw received from the edge of the SH contributes as a support force that supports only the screw W13. In addition, for example, the drag fw _y also contributes as a support force that supports the screw W13 and contributes as a support force that supports the driver 28, but as a support force that supports the driver 28 rather than a contribution rate as a support force that supports the screw W13. The amount of correction derived from the bearing force may be calculated by estimating the contribution ratio of the bearing.

When the screw W13 is screwed into the screw hole SH, the entire weight of the screw W13 is supported by the second object W23. Further, the supporting force with which the rear end of the screw W13 supports the driver 28 is also increased. That is, the supporting force with which the second object W23 supports the screw W13 and the driver 28 increases as the screw W13 rotates. Therefore, in the step of rotating the screw W13 after the tip of the screw W13 is hooked on the edge of the screw hole SH of the second object W23, the control device 3 increases the support force-derived correction amount according to the rotation angle. In this embodiment, the support force-derived correction amount is determined in advance as a function of the rotation angle of the driver 28. Thus, the support force-derived correction amount may be determined as a function of the control amount of the robot 1 such as the position, the rotation angle, and the force.

(6) Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that changes can be made without departing from the gist of the present invention. For example, in the step of holding the first object with the manipulator and moving it until it contacts the second object, the direction in which the first object is translated may be any direction. Therefore, in order to detect the contact between the first object and the second object, the direction in which the force acting on the first object other than gravity is detected by the force detector may be any direction. Further, in order to detect contact between the first object and the second object, the direction in which the displacement of the first object is detected may be any direction.

In addition, the vertical component of the operating force of the manipulator on the first object only needs to change according to the support force of the second object on the first object, and the target force in the impedance control is determined based on the support force-derived correction amount. For example, gravity compensation may be performed dynamically while maintaining the target force even after contact. Here, as a method of dynamically performing the gravity compensation, for example, the robot 1 is stopped during the process in which the supporting force acts on the first object from the second object or at the start of the process, and the detected value of the force sensor FS is set. By setting the offset so that the acting force f _s derived based on it becomes zero, it is possible to change the vertical component of the operating force of the manipulator on the first object. Further, for example, during the process in which the supporting force acts on the first object from the second object or at the start of the process, the acting force f _s is based on a predetermined value or function.
By changing the offset value by a predetermined amount, the vertical component of the operating force of the manipulator on the first object can be changed.

In addition, the impedance control in the operation in which the entire weight of the first object is supported by the second object immediately after the first object and the second object come into contact with each other is not included in the technical scope of the present invention. That is, the present invention moves the first object so that the contact point between the first object and the second object and the center of gravity of the first object are not aligned in the vertical direction. Before and after a part of the weight of the manipulator is supported by the second object, the vertical component of the operating force of the manipulator on the first object is changed according to the support force of the second object on the first object. is there.

DESCRIPTION OF SYMBOLS 1 ... Robot, 2 ... End effector, 3 ... Control apparatus, 4 ... Teaching terminal, 10 ... Arm,
DESCRIPTION OF SYMBOLS 20 ... Gripper, 22 ... Drive part, 23 ... Chuck, 25 ... Thunder, 28 ... Driver, 31 ... Power supply part, 32 ... Control part, 43 ... Display, A ... Arm, A1-A6 ... Arm member, W11 ... First Object, W13 ... Screw, W21-W23 ... Second object, E1-E6 ...
Encoder, H ... hole, J1-J6 ... joint, M1-M6 ... motor, O ... origin of force sensor, SH ... screw hole

Claims (6)

A manipulator,
A force detector for detecting a force acting on the manipulator;
An actuator for driving the manipulator;
An encoder for detecting the displacement of the manipulator;
In a robot comprising
When the first object comes into contact with the second object by holding and moving the first object, the manipulator moves the manipulator according to the supporting force of the second object with respect to the first object. Making the vertical component of the operating force on the first object smaller than before the contact;
robot. The force detector detects that the first object has contacted the second object;
The robot according to claim 1. The force detector detects that the first object has contacted the second object according to a force acting in a non-vertical direction;
The robot according to claim 2. The encoder detects that the first object has contacted the second object;
The robot according to claim 1. The encoder detects that the first object is in contact with the second object according to a non-vertical displacement;
The robot according to claim 4. A manipulator,
A force detector for detecting a force acting on the manipulator;
An actuator for driving the manipulator;
An encoder for detecting the displacement of the manipulator;
A robot comprising:
When the first object contacts the second object by holding and moving the first object with the manipulator, the manipulator of the manipulator according to the supporting force of the second object with respect to the first object A robot controller that reduces the vertical component of the operating force on the first object as compared to before the contact;
A robot system comprising:

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