JP2023005671A - Multijoint robot arm, driving method of multijoint robot arm, control device, and computer program - Google Patents

Abstract

To provide a multijoint robot arm capable of reducing unstable operation due to a weight of a target object, a driving method of the multijoint robot arm, a control device, and a computer program.SOLUTION: A multijoint robot arm according to an aspect of the present invention includes: a first link; a first actuator configured to be able to move an end of the first link in the vertical direction by rotating the first link according to a first rotational axis facing in a horizontal direction; a second link connected to the first link; and a second actuator configured to be able to move an end of the second link. The multijoint robot arm further includes a restraining part that restrains movement of the end of the first link in the vertical direction by the first actuator while the second actuator moves the end of the second link.SELECTED DRAWING: Figure 1

Description

The present invention relates to an articulated robot arm, an articulated robot arm driving method, a control device, and a computer program.

2. Description of the Related Art Conventionally, a multi-joint robot arm is known in which a plurality of links are connected via joints provided with actuators. For example, Patent Literature 1 discloses a working robot that has two joints, an upper arm driving means having an angle sensor at the upper joint portion, and a lower arm driving means having an angle sensor at the lower joint portion. is described. Further, Patent Literature 2 describes a transport system for holding cargo together with an articulated robot arm by a balancer arm provided separately from the articulated robot arm.

JP-A-5-340107 JP 2009-262304 A

However, when an external force such as vibration is applied to the robot arm, oscillation or control error may occur due to vibration amplitude or the like. Such an inconvenience becomes significant when the weight of the object is large, or when the robot arm is used to assist another transport device as described above.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an articulated robot arm, a method for driving the articulated robot arm, a control device, and a computer program that can reduce the instability of motion due to the weight of an object. .

An articulated robot arm according to one aspect of the present invention is configured such that the end of the first link can be moved vertically by rotating the first link according to the first link and the first rotating shaft oriented in the horizontal direction. a first actuator configured, a second link connected to the first link, and a second actuator configured to move an end of the second link; A restraining portion restrains vertical movement of the end portion of the first link by the first actuator while moving the portion.

According to this aspect, in the articulated robot arm, while the second actuator is moving the end of the second link, the restraining section is configured to move the end of the first link in the vertical direction by the first actuator. constrain the Therefore, the influence of the moment of force exerted by the weight of the object on the rotation axis of the first actuator is reduced, thereby reducing the possibility that the weight of the object causes the operation of the articulated robot arm to become unstable.

Advantageous Effects of Invention According to the present invention, it is possible to provide an articulated robot arm, a method for driving the articulated robot arm, a control device, and a computer program that can reduce the instability of the motion due to the weight of an object.

It is a block diagram showing an example of functional composition of robot system 100 concerning a 1st embodiment. 1 is a schematic diagram showing an example of the appearance of a robot arm 20 included in a robot system 100 according to a first embodiment; FIG. FIG. 11 is a diagram for explaining a method of determining active restraint portions and inactive restraint portions by a determination unit 10D; 4 is a flow chart showing an example of an operation method of the robot system 100 according to the first embodiment; It is a block diagram showing an example of functional composition of conveyance system 200 concerning a 2nd embodiment. FIG. 10 is a schematic diagram showing an example of the appearance of a robot arm 20 and a transport device 30 included in a transport system 200 according to a second embodiment;

An embodiment of the present invention will be described below with reference to the drawings. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention only to those embodiments.

[First embodiment]
FIG. 1 is a block diagram showing an example of the functional configuration of a robot system 100 according to the first embodiment. FIG. 2 is a schematic diagram showing an example of the appearance of the robot arm 20 included in the robot system 100 according to the first embodiment. FIG. 2 shows an orthogonal coordinate system of XYZ axes. The Z-axis is oriented vertically, the X-axis is oriented horizontally, and the Y-axis is oriented horizontally. It is assumed that the X-axis and the Y-axis are perpendicular to each other.

A robot system 100 includes a control device 10 and a robot arm 20 . The robot system 100 performs an operation of holding an object W (work) and transporting the object W. As shown in FIG. The present invention is not necessarily limited to a robot arm having a function of holding and transporting an object W (workpiece), but can be applied to a robot arm having a function of moving widely.

The robot arm 20 is an articulated robot arm including a base 20B, multiple links 20L, multiple joints 20J, and an end effector 20E, as shown in FIG.

The base 20B is arranged at one end of the robot arm 20 and installed at an installation location such as a floor or a wall. The base 20B is provided on the floor surface F so as to extend in the Z-axis direction, and other components of the robot arm 20 are mounted on the top. In addition, the robot arm 20 may further include a base driving section configured by an electric actuator or the like controlled by the control device 10 or the like and driving the base 20B. The base 20B may be configured to be movable on the floor surface F or the like by the base driving section.

The end effector 20E (an example of a “holding mechanism”) is arranged at the end of the robot arm 20 opposite to the base 20B and has a function of holding the object W. Specifically, the end effector 20E includes movable plates 20E1 and 20E2 that are opened and closed by an actuator. Thereby, the end effector 20E can hold the object W by sandwiching the object W with the movable plates 20E1 and 20E2. The configuration of the end effector 20E is not limited to the one described above. It may be provided with an actuator that generates a negative pressure in or hold the object W by an electromagnetic force.

The link 20L is made of, for example, a rigid member, and is continuously connected between the base 20B and the end effector 20E via each joint 20J. One end of the link 20L is connected to one joint 20J, and the other end of the link 20L is connected to another joint 20J. The link 20L may extend linearly or may be curved at any position.

The joint 20J is, for example, a connecting portion between the base 20B and the link 20L, a connecting portion between the two links 20L, or a connecting portion between the link 20L and the end effector 20E, and can also be called a "joint" in the articulated robot arm. . Each joint 20J is provided with, for example, a series elastic actuator 20D and a restraining portion 20R. In this embodiment, the series elastic actuator 20D and the restraining portion 20R provided on the same joint 20J are sometimes referred to as "corresponding" to each other.

For example, the series elastic actuator 20D is connected to the link 20L connected at the joint 20J (in the case of the joint 20J connecting two links 20L, the link closer to the end effector 20E) according to the control by the actuator control unit 10A, which will be described later. By rotating the link 20L) along the rotational axis of the series elastic actuator 20D, the end of the link 20L (opposite to the joint 20J) can be moved.

The direction of the rotation axis of the series elastic actuator 20D can be changed depending on the design, posture, etc. of the robot arm 20. FIG. Also, the moving direction of the end of the link 20L can be defined according to the direction of the rotation axis of the series elastic actuator 20D. For example, when the rotation axis of the series elastic actuator 20D is parallel to the horizontal direction, the moving direction of the end of the link 20L has a vertical component (the direction in which gravity acts). Further, for example, when the rotation axis of the series elastic actuator 20D is parallel to the vertical direction, the moving direction of the end of the link 20L has a horizontal component.

The series elastic actuator 20D may be flexible. "Flexible" means having elasticity, viscosity, or elasticity and viscosity. Elasticity refers to the property of deforming when stress is applied and returning to its original state when stress is removed, and is sometimes expressed by the word flexibility, which indicates ease of elastic deformation. Viscosity refers to the property of producing a stress that equalizes the flow velocity of a fluid. A flexible drive mechanism may include at least one of, for example, a magnetic fluid, a mechanical spring, an air spring, a magnetic force spring, and a vane motor to provide flexibility.

The series elastic actuator 20D includes, for example, a drive section 20DA, an elastic body 20DE, and a sensor 20DS.

The driving unit 20DA is composed of, for example, a servomotor driven by a control signal supplied from the control device 10, or the like. The elastic body 20DE is composed of, for example, a mechanical spring. In the series elastic actuator 20D, the power output from the driving section 20DA is transmitted to the link 20L on the output side via the elastic body 20DE, and the link 20L rotates around the rotation axis of the series elastic actuator 20D.

The sensor 20DS is connected to, for example, the drive unit 20DA, detects the reference position of the robot arm 20 (hereinafter referred to as "reference position") by acquiring the displacement amount of the mechanical spring, and detects the reference position. The information shown is supplied to the control device 10 . The reference position of the robot arm 20 may be any position of the robot arm 20 . The unit of the reference position may be of any format according to the aspect of the part of the robot arm 20 corresponding to the reference position. For example, the reference position may be the link 20L that configures the robot arm 20, and in this case, the reference position can be expressed as angle information. Alternatively, the reference position may be the hand position of the robot arm 20 (for example, the center point of the end effector 20E), and in this case the reference position can be expressed as three-dimensional position information.

The sensor 20DS may further be configured as, for example, an acceleration sensor, detect the orientation of the rotation axis of the series elastic actuator 20D, and supply information indicating the orientation of the rotation axis of the series elastic actuator 20D to the control device 10. good. The information indicating the orientation of the rotation axis of the series elastic actuator 20D can be arbitrarily defined, but may be defined, for example, by rotation angles around each axis in a three-axis orthogonal coordinate system.

For example, the restraining section 20R exerts a force against the rotation of the link 20L by the series elastic actuator 20D under the control of the restraining section control section 10B, which will be described later. It has the function of executing an operation that restricts movement in the vertical direction (restraint operation). Here, "restraining" is not limited to applying a force against the rotation of the link 20L to such an extent as to completely prevent the vertical movement of the end of the link 20L. It may involve exerting a force against rotation of the link 20L to the extent that it does not completely prevent directional movement. The configuration of the restraining portion 20R is not particularly limited, and may be, for example, a brake pad that exerts a frictional force on the series elastic actuator 20D, or an engaging portion ( convex portion). In addition, "movement in the vertical direction" with respect to the restraint action may include both "upward movement in the vertical direction" and "downward movement in the vertical direction". The movement is not limited to completely parallel movement, and may include the case where the difference between the vertical direction and the movement direction is equal to or less than a predetermined angle.

As shown in FIG. 1, the robot arm 20 has a weight sensor (an example of a detection unit). The weight sensor 20G detects, for example, the weight of the object W held by the end effector 20E and supplies a signal indicating the weight of the object W to the control device 10 .

Under the above configuration, the inertia, mass and length of the portion driven by the series elastic actuator 20D corresponding to the flexible drive mechanism, the external force, and the spring constant of the mechanical spring, which is the elastic body 20DE, are used as parameters. An equation of motion is established. Therefore, the control device 10 is configured to perform mechanical compliance control for controlling impedance based on the spring constant and displacement amount of the mechanical spring.

The series elastic actuator 20D may be connected to the drive shaft of the servomotor, which is the drive unit 20DA, and may include a gear that transmits power to the mechanical spring. Further, the series elastic actuator 20D may include a damper mechanism for damping impact based on viscosity and a clutch mechanism for switching power transmission. When applying a viscous body such as a viscous damper mechanism, a viscous constant is added as a parameter to the equation of motion. For example, an equation of motion is established in which a value obtained by multiplying the viscosity constant by the time change of the link angle is taken into account as the torque.

As shown in FIG. 1, the control device 10 includes, for example, an actuator control section 10A, a constraint section control section 10B, an operation mode determination section 10C, a determination section 10D, and a constraint condition determination section 10E.

The actuator control section 10A controls rotation of the link 20L by the series elastic actuator 20D, for example, by supplying a control signal to the driving section 20DA of the series elastic actuator 20D. The actuator control unit 10A supplies a control signal to each driving unit 20DA based on information (start position, target position, route information, allowable range, etc.) defining the operation of the robot arm 20 acquired from a teaching device (not shown). may be generated. The teaching device may be a teaching device according to online teaching that actually moves the robot arm 20 on site and teaches the reference position and orientation at that time as the starting position, or a teaching device that uses the position and orientation of the reference position as the starting position by a computer program. It may be a teaching device that follows off-line teaching such as text type, simulator type, emulator type, or automatic teaching type.

The restraining section control section 10B, for example, supplies a control signal to a predetermined restraining section 20R, thereby controlling the restraining section 20R to perform a restraining operation. For example, when the constraint condition determination unit 10E determines that the constraint condition determination unit 10E satisfies a predetermined constraint condition for the constraint unit 20R determined as the active constraint unit, the constraint unit control unit 10B controls the constraint unit 20R. A control signal may be supplied to the restraining section 20R to cause the restraining section 20R to perform the restraining operation. For example, the restraining section control section 10B does not have to supply a control signal for executing a restraining operation to a restraining section 20R determined as an inactive restraining section, which will be described later. good too. Further, for example, when the operation mode of the robot system 100 is set to the normal operation mode described later, the restraining unit control unit 10B sends a control signal for executing the restraining operation to any of the restraining units 20R. need not be supplied.

The operation mode determination unit 10C determines the operation mode of the robot system 100, for example. Here, the operation modes are a normal operation mode in which none of the restraining units 20R provided in the robot arm 20 perform a restraining operation, and a normal operation mode in which at least one of the restraining units 20R provided in the robot arm 20 can perform a restraining operation under predetermined conditions. and a constrained mode of operation. The operation mode determination unit 10C may determine the operation mode of the robot system 100, for example, based on the operation mode set by the operator via the operation unit (not shown).

The determining unit 10D may determine, for example, at least one of the plurality of restraining units 20R to be an active restraining unit that can perform a restraining operation. The series elastic actuator 20D corresponding to the restraint portion 20R determined as the active restraint portion is an example of the "first actuator", and the link 20L connected to the end effector 20E side of the joint 20J provided with the restraint portion 20R. is an example of a "first link". Further, the determining unit 10D, for example, selects at least one of the plurality of restraining units 20R (for example, the restraining unit 20R other than the restraining unit 20R determined as the active restraining unit) as a restraining unit that cannot perform the restraining operation. It may be determined to be some inactive constraint. The series elastic actuator 20D corresponding to the restraining portion 20R determined as the inactive restraining portion is an example of the "second actuator", and the link 20L connected to the end effector 20E of the joint 20J provided with the restraining portion 20R. is an example of a "second link".

Here, with reference to FIG. 3, a more detailed description will be given of how the determining unit 10D determines the active and inactive restraints. FIG. 3 shows the robot arm 20 according to the first embodiment so that the rotation axis of the joint 20J (that is, the rotation axis of the series elastic actuator 20D provided at the joint 20J) and the orientation of the link 20L can be easily grasped. The appearance is shown schematically. The robot arm 20 shown in the figure is configured as a 7-axis articulated robot arm, and includes a base 20B, joints 20J1 to 20J7, a link 20LB, 20L1 to 20L7, and an end effector 20E. Link 20LB is connected between base 20B and joint 20J1, link 20L1 is connected between joint 20J1 and joint 20J2, link 20L2 is connected between joint 20J2 and joint 20J3, link 20L3 is connected between joints 20J3 and 20J4, link 20L4 is connected between joints 20J4 and 20J5, link 20L5 is connected between joints 20J5 and 20J6, and link 20L6 is connected between joints 20J4 and 20J5. It is connected between the joint 20J6 and the end effector 20E. FIG. 3 also shows an orthogonal coordinate system of XYZ axes. The Z-axis is oriented vertically, the X-axis is oriented horizontally, and the Y-axis is oriented horizontally. It is assumed that the X-axis and Y-axis are perpendicular to each other.

In each series elastic actuator 20D, a moment of force due to the respective weights of the components of the robot arm 20 and the object W is generated around the rotation axis according to the direction of the rotation axis of the series elastic actuator 20D. obtain. Specifically, in each series elastic actuator 20D, the weight of each link 20L and each joint 20J arranged between the joint 20J in which the series elastic actuator 20D is provided and the end effector 20E, the weight of the end effector 20E Due to the weight, the weight of the object W, etc., a moment of force about the axis of rotation can occur. The moment of the force increases as the rotation axis of the series elastic actuator 20D approaches the horizontal direction.

Under this premise, the determination unit 10D may determine the active restraint portion and the inactive restraint portion, for example, based on the magnitude of the moment of force about the rotation axis of the series elastic actuator 20D. .

In the example shown in FIG. 3, the rotation axes of joints 20J1, 20J3, and 20J7 are substantially parallel to the Z-axis direction (vertical direction), and the rotation axes of joints 20J2 and 20J5 are substantially parallel to the X-axis direction (horizontal direction). , and the rotation axes of the joints 20J4 and 20J6 are substantially parallel to the Y-axis direction (horizontal direction). Therefore, of the joints 20J of the robot arm 20, joints 20J2, 20J4, 20J5, and 20J6 have rotation axes that are not substantially parallel to the Z-axis direction (have a horizontal component). , 20J4, 20J5 and 20J6, moments of force about the axis of rotation can occur. Since the rotation axes of the joints 20J2, 20J4, 20J5, and 20J6 are all substantially parallel to the horizontal direction, the moment of force around the rotation axis increases as the connecting position in the robot arm 20 is closer to the base 20B. That is, the moment of force around the rotation axis is the joint 20J2, the joint 20J4, the joint 20J5, and the joint 20J6 in descending order. Therefore, the determining unit 10D may determine, for example, the restraining portion 20R of the joint 20J2 to be the active restraining portion, and may further determine the restraining portion 20R of the joint 20J4 to be the active restraining portion. Then, the determining unit 10D may determine the restraining portions 20R other than the restraining portions 20R determined as the active restraining portions to be the inactive restraining portions. Note that the ratio of the restraint portions 20R determined as the active restraint portions to the restraint portions 20R included in the robot arm 20 is not limited to the above-described ratio, and may be arbitrarily set.

The posture of the robot arm 20 shown in FIG. 3 may be the posture at any time regardless of whether the robot system 100 is in operation. Then, the determination unit 10D may determine the active restraint portion and the inactive restraint portion from the plurality of restraint portions 20R, for example, by the above-described method or the like at any of these time points. During operation of the robot system 100, the determining unit 10D acquires the direction of the rotation axis of each joint 20J (the rotation axis of the series elastic actuator 20D) from the sensor 20DS provided at each joint 20J. , the active constraint and the inactive constraint may be determined based on the orientation of the axis of rotation.

Note that the determination unit 10D may determine, for example, the active restraint portion and the inactive restraint portion from the plurality of restraint portions 20R based on the operator's selection. For example, when the operator selects an active restraint portion and an inactive restraint portion from among the plurality of restraint portions 20R via an operation unit (not shown), the determination unit 10D receives the selection, Depending on the selection, each restraining portion 20R may be determined as an active restraining portion or an inactive restraining portion.

As described above, in the robot arm 20 according to the present embodiment, at least one of the plurality of restraining sections 20R is determined as the active restraining section, and the restraining section 20R can perform the restraining operation. This makes it possible to prevent errors due to an excessive load on the joint 20J, control oscillation, elastic portion vibration of the series elastic actuator 20D, and the like. In particular, by determining the active restraint portion based on the magnitude of the moment of force about the rotation axis of the series elastic actuator 20D, the effects described above (such as errors due to excessive load, control oscillation, and vibration of the elastic portion of the series elastic actuator 20D) can be reduced. etc.) can be enhanced.

For example, when a condition (constraint condition) for executing a constraining motion is set for the active constraint unit, the constraint condition determination unit 10E determines whether or not the constraint condition is satisfied. The constraint may be defined based on the weight of the object W. For example, the constraint condition determination unit 10E may acquire the weight of the object W detected by the weight sensor 20G included in the robot arm 20, and determine the constraint condition based on this. Alternatively, the constraint condition determination unit 10E may determine the constraint condition, for example, based on the weight of the object W input by the operator.

For example, the constraint condition may include that the weight of the object W is equal to or greater than a first threshold (or greater than the first threshold). The first threshold may be set arbitrarily, and may be, for example, a continuous allowable load that is the value of the weight of the object W that can be continuously held by the robot arm 20 for a predetermined period. Further, for example, the constraint condition may include that the weight of the object W is equal to or less than a second threshold (or smaller than or less than the second threshold). The second threshold may be set arbitrarily, and may be, for example, an instantaneous allowable load that is the value of the weight of the object W that the robot arm 20 can momentarily hold. As described above, the constraint condition may be, for example, "continuous permissible load ≤ (<) weight of object W ≤ (<) momentary permissible load".

With respect to the hardware configuration, the control device 10 includes, for example, a CPU (Central Processing Unit), a GPU (Graphical Processing Unit) and other processors such as arithmetic elements, SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), and the like. Memory) and other volatile memory elements, NOR flash memory, NAND flash memory, HDD (Hard Disc Drive) and other non-volatile memory elements, and communication means such as a bus that connects them. It can be constructed from a computer. The nonvolatile memory element stores, for example, a computer program for executing each process shown in this embodiment. Volatile storage elements temporarily store at least part of these computer programs, arithmetic processing results, and the like. However, at least part of these arithmetic elements, non-volatile memory elements, etc. may be installed at remote locations connected to a communication network such as the Internet. For example, the computing element may be configured to obtain computer programs or required data via a communication network.

FIG. 4 is a flow chart showing an example of the operation method of the robot system 100 according to the first embodiment.

(S11) First, the operation mode determination unit 10C determines the operation mode of the robot system 100. FIG. The operation mode determination unit 10C may determine the operation mode of the robot system 100, for example, based on the operation mode set by the operator via the operation unit (not shown). The operation mode is, for example, a normal operation mode in which none of the restraining units 20R provided in the robot arm 20 performs a restraining operation, and a restraining operation mode in which at least one of the restraining units 20R provided in the robot arm 20 can perform a restraining operation under predetermined conditions. mode of operation.

(S12) When the operation mode determination unit 10C determines that the operation mode of the robot system 100 is set to the "normal operation mode", the control device 10 causes the restraint unit 20R of the robot arm 20 to perform the restraint operation. The robot arm 20 is controlled by a normal operation mode that does not execute . Specifically, the actuator control section 10A controls rotation of the link 20L by the series elastic actuator 20D by supplying a control signal to the driving section 20DA of the series elastic actuator 20D. Further, the restraining section control section 10B does not supply any control signal for executing the restraining operation to any of the restraining sections 20R.

(S13) When the motion mode determination unit 10C determines that the motion mode of the robot system 100 is set to the “restricted motion mode”, the control device 10 determines that at least one of the restraint units 20R included in the robot arm 20 is in a predetermined state. The robot arm 20 is controlled by a restricted operation mode that can perform restricted operation under certain conditions. First, the determination unit 10D determines active restraint portions and inactive restraint portions from a plurality of restraint portions 20R. For example, as described with reference to FIG. 3, the determination unit 10D may determine the active restraint portion and the inactive restraint portion based on the magnitude of the moment of force about the rotation axis of the series elastic actuator 20D. . Alternatively, the determination unit 10D may determine, for example, the active restraint portion and the inactive restraint portion from the plurality of restraint portions 20R based on the operator's selection. In this case, the determining unit 10D, for example, responds to the operator selecting the active restraining portion and the non-active restraining portion from among the plurality of restraining portions 20R via an operation unit (not shown). may be received, and each restraint portion 20R may be determined as an active restraint portion or an inactive restraint portion according to the selection.

(S14) Next, the constraint condition determination unit 10E determines whether or not the constraint condition is satisfied when a condition (constraint condition) for executing the constraint operation is set for the active constraint unit. The constraint may be defined based on the weight of the object W. For example, the constraint condition determination unit 10E may acquire the weight of the object W detected by the weight sensor 20G included in the robot arm 20, and determine the constraint condition based on this. Alternatively, the constraint condition determination unit 10E may determine the constraint condition, for example, based on the weight of the object W input by the operator. For example, when "continuous allowable load≤weight of object W≤instantaneous allowable load" is set as a constraint condition, the constraint condition determination unit 10E determines whether or not the weight of the object W satisfies the constraint condition. do.

(S15) When the constraint condition determination unit 10E determines that the constraint condition is satisfied, the control device 10 causes the constraint unit 20R, which has been determined to be the active constraint unit in step S13, to perform the constraint operation, Control actuator 20D. Specifically, the actuator control section 10A controls rotation of the link 20L by the series elastic actuator 20D by supplying a control signal to the driving section 20DA of the series elastic actuator 20D. Further, the restraining section control section 10B supplies a control signal to the restraining section 20R determined as the active restraining section, thereby causing the restraining section 20R to perform the restraining operation. On the other hand, the restraining section control section 10B does not supply a control signal for executing the restraining operation to the restraining section 20R determined as the inactive restraining section. As a result, while the series elastic actuator 20D (an example of the second actuator) corresponding to the restraining portion 20R determined as the inactive restraining portion moves the end of the link 20L (an example of the second link), The restraining portion 20R determined as the restraining portion restrains the vertical movement of the end of the link 20L (first link) by the corresponding series elastic actuator 20D (an example of the first actuator).

(S16) When the constraint condition determination unit 10E determines that the constraint condition is not satisfied, the control device 10 controls the constraint unit 20R determined to be the active constraint unit and the constraint unit determined to be the inactive constraint unit in step S13. The series elastic actuator 20D is controlled while preventing any of the sections 20R from performing the restraining operation. Specifically, the actuator control section 10A controls rotation of the link 20L by the series elastic actuator 20D by supplying a control signal to the driving section 20DA of the series elastic actuator 20D. Furthermore, the restraining section control section 10B does not supply a control signal for executing the restraining operation to either the restraining section 20R determined to be the active restraining section or the restraining section 20R determined to be the inactive restraining section. . Thus, the motion processing by the robot system 100 ends.

In the restraint operation mode, the active restraint portion and the inactive restraint portion are re-determined by the determination unit 10D at an arbitrary time (for example, periodic time) during the operation of the robot arm 20 (step S13). After the constraint condition is appropriately determined by the condition determination unit 10E (step S14), the series elastic actuator 20D is controlled with a constraint operation (step S15) or the series elastic actuator 20D without a constraint operation is controlled (step S16). ) may be executed. This makes it possible to adaptively prevent errors due to excessive load on the joint 20J, control oscillation, elastic part vibration of the series elastic actuator 20D, and the like even during the operation of the robot arm 20. FIG.

[Second embodiment]
FIG. 5 is a block diagram showing an example of the functional configuration of the transport system 200 according to the second embodiment. FIG. 6 is a schematic diagram showing an example of the appearance of the robot arm 20 and the transport device 30 included in the transport system 200 according to the second embodiment. FIG. 6 shows an orthogonal coordinate system of XYZ axes. The Z-axis is oriented vertically, the X-axis is oriented horizontally, and the Y-axis is oriented horizontally. It is assumed that the X-axis and Y-axis are perpendicular to each other.

The transport system 200 is a system for transporting the target object W. As shown in FIG. The transport system 200 includes a control device 11 , a robot arm 20 and a transport device 30 .

The transport device 30 is an example of a transport device for transporting the object W. As shown in FIG. The transport device 30 may be any device such as a crane having any configuration such as a hoist crane or a jib crane, a belt conveyor, or a forklift, as long as the object W can be transported. A conveying device 30 according to the second embodiment is configured as a hoist crane, for example, and includes a side frame 31, an upper frame 32, a hoist 33, and a wire 34, for example. An object W is attached to the tip of the wire 34 directly or via a jig or the like (not shown).

The side frame 31 is erected on the floor surface F so as to extend in the Z-axis direction. An upper frame 32 extending in the X-axis direction is connected near the top of the side frame 31 . A guide rail (not shown) is provided on the upper frame 32 along the X-axis direction. In addition, when the transport device 30 is configured as a jib crane, the side frame 31 may include a turning shaft facing the Z-axis direction, and the upper frame 32 may be configured to be rotatable around the turning shaft. .

The hoist 33 is attached to a guide rail (not shown) provided on the upper frame 32 via a hoist driving section 30A. The hoist drive section 30A has, for example, an electric actuator or the like, and is driven by a control signal supplied from the control device 11. As shown in FIG. The hoist 33 is movable along the extending direction (X-axis direction) of the upper frame 32 as indicated by the arrow A in accordance with the driving of the hoist driving section 30A.

A flexible wire 34 is wound around the hoist 33 and suspended. The hoist 33 is provided with a wire driving section 30B. The wire drive section 30B has, for example, a servomotor or the like, and controls winding up and rewinding of the wire 34 based on control signals supplied from the control device 11 . The tip of the wire 34 is configured so that the object W can be attached. The object W attached to the tip of the wire 34 is movable in the vertical direction (Z-axis direction) as indicated by the arrow B in accordance with the driving of the wire driving section 30B.

In addition, instead of the hoist 33 and the wire 34 hanging from the hoist 33 as a configuration for conveying the object W, the conveying device 30 includes a member such as a rod-shaped piston having rigidity, and a member such as the piston in the Z-axis direction. A cylinder configured to be slidable may be provided. Like the hoist 33 , the cylinder may be configured to be movable in the X-axis direction along guide rails provided on the upper frame 32 .

The hoist 33 is equipped with a sensor 30C. Sensor 30C may be able to detect, for example, a pulling force that occurs on wire 34 . The sensor 30</b>C generates a detection signal corresponding to detection of various forces, and supplies the detection signal to the control device 11 .

In addition to the components of the control device 10 according to the first embodiment (actuator control section 10A, restraint section control section 10B, operation mode determination section 10C, determination section 10D, and restraint condition determination section 10E), the control device 11 includes: It further includes a transport device control unit 10F.

The conveying device control section 10F drives the conveying device 30 by supplying control signals to each of the hoist driving section 30A and the wire driving section 30B provided in the conveying device 30 . The carrier device control section 10F may control the carrier device 30 in synchronization with the robot arm 20 .

The robot arm 20 may have the same configuration as the first embodiment. The robot arm 20 is an example of a robot for assisting the transport of the object W by the transport device 30 . The robot arm 20 can, for example, hold the wire 34 and the object W via the end effector 20E and apply a predetermined force to assist the transport of the object W. For example, when the transfer device 30 moves the object W along the X-axis direction, the robot arm 20 may apply force to the wire 34 or the object W so as to assist the movement. . Further, for example, when the transfer device 30 moves the object W along the Z-axis direction, the robot arm 20 applies a force to the wire 34 and the object W so as to assist the movement. good too. Thus, when the robot arm 20 assists the movement of the object W by the transfer device 30, the actuator control section 10A controls the series elastic actuator 20D provided at each joint 20J.

In particular, when the robot arm 20 assists the movement of the object W in the Z-axis direction by the transfer device 30, at least one of the restraint units 20R is controlled by the restraint unit control unit 10B to operate the series elastic actuator By applying a force that resists the rotation of the link 20L by 20D, the series elastic actuator 20D may perform an operation (restriction operation) that restricts movement of the end of the link 20L in the vertical direction. As a result, the robot arm 20 effectively assists the movement of the object W by the transfer device 30 while preventing errors due to an excessive load on the joint 20J, control oscillation, vibration of the elastic part of the series elastic actuator 20D, and the like. becomes possible.

The embodiments described above are for facilitating understanding of the present invention, and are not intended to limit and interpret the present invention. Each element included in the embodiment and its arrangement, materials, conditions, shape, size, etc. are not limited to those illustrated and can be changed as appropriate. Also, it is possible to partially replace or combine the configurations shown in different embodiments.

DESCRIPTION OF SYMBOLS 10... Control apparatus, 10A... Actuator control part, 10B... Restriction part control part, 10C... Operation mode determination part, 10D... Determination part, 10E... Restriction condition determination part, 10E... and restriction condition determination part, 10F... Conveying apparatus control Part 11... Control device 20... Robot arm 20B... Base 20D... Series elastic actuator 20DA... Drive part 20DE... Elastic body 20DS... Sensor 20E... End effector 20E1... Movable plate 20E2... Movable plate , 20G... weight sensor, 20J... joint, 20J1... joint, 20J2... joint, 20J3... joint, 20J4... joint, 20J5... joint, 20J6... joint, 20J7... joint, 20L... link, 20L1... link, 20L2... link, 20L3... link, 20L4... link, 20L5... link, 20L6... link, 20LB... link, 20R... restraint part, 30... robot arm, 30A... hoist drive part, 30B... wire drive part, 30C... sensor, 31... side part Frame 32 Upper frame 33 Hoist 34 Wire 100 Robot system 200 Transport system

Claims (10)

a first link;
a first actuator configured to be able to move the end of the first link in the vertical direction by rotating the first link along a first rotating shaft oriented in the horizontal direction;
a second link connected to the first link;
a second actuator configured to move the end of the second link,
further comprising a restraining section that restrains vertical movement of the end of the first link by the first actuator while the second actuator moves the end of the second link;
Articulated robot arm. a holding mechanism for holding an object;
A detection unit that detects the weight of the object,
When the weight satisfies a predetermined condition, the restraining section vertically lifts the end of the first link by the first actuator while the second actuator moves the end of the second link. 2. The articulated robotic arm of claim 1 constrained from moving in a direction. 3. The articulated robot arm according to claim 2, wherein said predetermined condition includes that said weight is greater than or equal to a first threshold. The articulated robot arm according to claim 3, wherein the first threshold is a continuous allowable load of the articulated robot arm. The articulated robot arm according to any one of claims 2 to 4, wherein said predetermined condition includes that said weight is equal to or less than a second threshold. 6. The articulated robot arm according to claim 5, wherein said second threshold is an instantaneous allowable load of said articulated robot arm. The articulated robot arm according to any one of claims 1 to 6, wherein at least one of the first actuator and the second actuator has flexibility. a first link;
a first actuator configured to be able to move the end of the first link in the vertical direction by rotating the first link along a first rotating shaft oriented in the horizontal direction;
a second link connected to the first link;
a second actuator configured to move the end of the second link;
A method for driving an articulated robot arm, comprising: a restraining unit configured to restrain vertical movement of the end of the first link by the first actuator, the method comprising:
using the restraining section to restrain vertical movement of the end of the first link while the second actuator moves the end of the second link. How to drive a robot arm. a first link;
a first actuator configured to be able to move the end of the first link in the vertical direction by rotating the first link along a first rotating shaft oriented in the horizontal direction;
a second link connected to the first link;
a second actuator configured to move the end of the second link;
A control device for controlling an articulated robot arm, comprising: a restraint unit configured to restrain movement of the end of the first link in the vertical direction by the first actuator,
restraining vertical movement of the end of the first link using the restraining portion while the second actuator moves the end of the second link. controller. a first link;
a first actuator configured to be able to move the end of the first link in the vertical direction by rotating the first link along a first rotating shaft oriented in the horizontal direction;
a second link connected to the first link;
a second actuator configured to move the end of the second link;
and a restraint unit configured to restrain vertical movement of the end portion of the first link by the first actuator, the control device comprising a computer for controlling an articulated robot arm. ,
restraining vertical movement of the end of the first link using the restraining portion while the second actuator moves the end of the second link. A computer program that generates control instructions.

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