JP2022064094A - Operation method, robot system, control device, teaching method, and program - Google Patents

Abstract

To provide an operation method, a robot system, a control device, a teaching method and a computer program which facilitate appropriate setting of an allowable range in movement of a robot arm.SOLUTION: An operation method includes: a step of acquiring information indicating a plan route to a target position; an acquisition step of acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range; a first moving step of moving a robot arm so that a reference position is arranged within the first allowable range relative to the plan route when a predetermined parameter indicating a degree of separation between the reference position and the target position of the robot arm is equal to or more than a predetermined threshold; and a second moving step of moving the robot arm so that the reference position is arranged within the second allowable range relative to the plan route when the predetermined parameter is less than the predetermined threshold.SELECTED DRAWING: Figure 4

Description

The present invention relates to an operation method, a robot system, a control device, a teaching method and a program.

In recent years, in the field of industrial robots, the technology of robots capable of realizing the movements desired by workers with high accuracy has been developed. In this field, for example, teaching a robot an operating range and moving the robot within the operating range are performed.

For example, in Patent Document 1, one or a plurality of parameters indicating the position and orientation of the robot are changed for each of the plurality of teaching points included in the teaching program of the robot, and each joint of the robot is changed. It is described that an operation margin amount indicating a region in which continuous operation is possible is calculated from the teaching point within the operation range, and this is quantitatively displayed numerically.

Japanese Unexamined Patent Publication No. 2009-226561

Regarding the operation of the robot arm, it is conceivable to move the robot arm so that the reference position of the robot arm is within a predetermined allowable range. In this respect, when the robot arm is located at a position relatively far from the target position, the allowable range may be large because high accuracy is not required for the movement of the robot arm. On the other hand, when the robot arm is relatively close to the target position, high accuracy is required for the movement of the robot arm, so that the allowable range is often desired to be small.

Therefore, it is an object of the present invention to provide an operation method, a robot system, a control device, a teaching method, and a program that facilitates setting an appropriate allowable range for movement of a robot arm.

The present disclosure provides a method of operating a robot arm. This operation method includes a step of acquiring information indicating a planned route to a target position, an acquisition step of acquiring information indicating a first allowable range, and information indicating a second allowable range smaller than the first allowable range. , When the predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm is equal to or more than the predetermined threshold value, the robot arm is arranged so that the reference position is within the first allowable range with respect to the planned path. A first movement step to move, and a second movement step to move the robot arm so that the reference position is within the second permissible range with respect to the planned path when the predetermined parameter is less than the predetermined threshold. including.

According to this, when the predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm is equal to or more than the predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. When the predetermined parameter is less than the predetermined threshold value, the robot arm is moved so that the reference position is within the second allowable range with respect to the planned path. Is possible. Therefore, it is possible to appropriately set the allowable range for the movement of the robot arm.

The present disclosure provides a robot system. This robot system is a robot system including a robot arm and a control device for controlling the robot arm, and the control device provides a means for acquiring information indicating a planned route to a target position and a first permissible range. When the acquisition means for acquiring the information to be shown and the information indicating the second allowable range smaller than the first allowable range, and the predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm are equal to or higher than the predetermined threshold value. In some cases, the first moving means for moving the robot arm so that the reference position is located within the first permissible range with respect to the planned path, and when the predetermined parameter is less than the predetermined threshold, the reference position is the planned path. A second moving means for moving the robot arm so as to be arranged within the second allowable range is provided.

The present disclosure provides a control device. This control device is a control device that controls a robot arm, and is a means for acquiring information indicating a planned route to a target position, information indicating a first allowable range, and a second allowable range smaller than the first allowable range. When the predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm and the acquisition means for acquiring the information indicating the above and below the predetermined threshold value, the reference position is the first permissible for the planned route. The first moving means for moving the robot arm so as to be arranged within the range, and when the predetermined parameter is less than the predetermined threshold, the reference position is arranged within the second allowable range with respect to the planned path. A second moving means for moving the robot arm is provided.

The present disclosure provides a teaching method. This teaching method is a teaching method for teaching an operation to a robot system including a robot arm and a control device for controlling the robot arm, and includes a step of acquiring information indicating a planned route to a target position and a first permissible range. The acquisition step for acquiring the information indicating the first allowable range and the information indicating the second allowable range smaller than the first allowable range, and the predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm are equal to or higher than the predetermined threshold. If, the first movement step to move the robot arm so that the reference position is located within the first permissible range with respect to the planned path, and if the predetermined parameter is less than the predetermined threshold, the reference position is planned. A second movement step of moving the robot arm so as to be arranged within the second allowable range with respect to the path, and a teaching for causing the robot system to execute the steps are given.

The present disclosure provides a computer program. This computer program acquires from the computer a step of acquiring information indicating a planned route to a target position, information indicating a first allowable range, and information indicating a second allowable range smaller than the first allowable range. When the predetermined parameter indicating the degree of separation between the acquisition step and the reference position and the target position of the robot arm is equal to or more than the predetermined threshold value, the reference position is placed within the first allowable range with respect to the planned path. The first movement step to move the robot arm and the second movement to move the robot arm so that the reference position is within the second permissible range with respect to the planned path when the predetermined parameter is less than the predetermined threshold. Step and execute.

It is a functional block diagram of a robot system 100. It is a schematic diagram which looked at the robot arm 20 which holds a fitting object from the side view. It is a schematic diagram which looked at the robot arm 20 which holds a fitting object from the upper surface. It is a schematic diagram for demonstrating the translational movement of a robot arm 20. It is a schematic diagram for demonstrating the rotational movement of a robot arm 20. It is a figure for demonstrating the permissible range. It is a flowchart which shows the process for giving the operation instruction to the robot system 100. It is a flowchart which shows the operation method of the robot system 100. It is a flowchart which shows the operation method of the movement processing of a robot system 100.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples for explaining the present invention, and the present invention is not intended to be limited only to the embodiments.

FIG. 1 is a functional block diagram of the robot system 100. 2A and 2B are schematic views showing a state in which an object, which is an insert component W, is fitted to an object, which is a mold M, by a robot arm 20 in a side view and a top view. The insert component W is formed in a disk shape, for example. The cylindrical recess formed in the mold M is formed, for example, slightly larger than the diameter of the insert component W (for example, 50 μm larger).

The robot system 100 includes a robot arm 20 and a control device 10 for controlling the robot arm 20. The robot system 100 according to the present embodiment holds an insert component W which is a fitting object (an example of an "object"), and the fitting object is a gold which is an object to be fitted (an example of an "object"). The fitting operation of assembling to the assembling portion of the mold M is executed. However, the present invention can be generally applied to an operation including an operation of moving the robot arm 20.

The robot arm 20 performs an operation including, for example, an operation of holding an object and bringing it into contact with an object (assembly site or the like). In particular, the robot arm 20 can make an object imitate an object. Here, "to imitate an object with respect to an object" means to move the object relative to the object while bringing the object into contact with the object. The relative movement is not limited to the translational movement of the object relative to the object, but also includes the rotational movement of the object relative to the object.

FIG. 3A is a schematic diagram showing a mode in which the robot arm 20 translates and moves an object relative to an object. In the figure, the end effector 20E and the object held by the end effector 20E when the reference position of the robot arm 20 coincides with the target position are shown by broken lines. On the other hand, the end effector 20E and the object held by the end effector 20E when the reference position of the robot arm 20 is separated from the target position are shown by a solid line. As shown by the broken line, when the reference position of the robot arm 20 coincides with the target position, the object (insert part W) held by the end effector 20E interferes with the object (mold M). .. However, in reality, due to the presence of the object, the end of the object comes into contact with the surface of the object. The displacement amount D1 corresponds to the amount of elastic deformation of the elastic body 20DE of the series elastic actuator 20D. At this time, a force based on the displacement amount and the spring constant acts from the object to the object.

FIG. 3B is a schematic diagram showing a mode in which the robot arm 20 rotates and moves an object relative to an object. In the figure, the end effector 20E and the object held by the end effector 20E when the reference position of the robot arm 20 coincides with the target position are shown by broken lines. On the other hand, the end effector 20E and the object held by the end effector 20E when the reference position of the robot arm 20 is separated from the target position are shown by a solid line. As shown by the broken line, when the reference position of the robot arm 20 coincides with the target position, the object (insert part W) held by the end effector 20E interferes with the object (mold M). .. However, in reality, due to the presence of the object, the side surface of the object comes into contact with the surface of the object. The displacement amount D2 corresponds to the amount of elastic deformation of the elastic body 20DE of the series elastic actuator 20D. At this time, a force based on the displacement amount and the spring constant acts from the object to the object.

Return to FIGS. 1, 2A, and 2B. The robot arm 20 is, for example, a vertical articulated robot, and is an end effector that can be held by sandwiching a base, a plurality of links 20L, a joint 20J connecting each link 20L, and an object between movable plates 20E1 and 20E2. 20E, one or more drive units 20A, and one or more series elastic actuators 20D. The plurality of links 20L are, for example, a link 20L corresponding to a lower arm portion rotatably attached to the body portion and a link 20L corresponding to an upper arm portion rotatably attached to the lower arm portion. And the link 20L corresponding to the wrist portion rotatably attached to the upper arm portion. For example, a series elastic actuator 20D for driving the link 20L corresponding to the lower arm portion is mounted on the joint 20J between the link 20L corresponding to the upper arm portion and the link 20L corresponding to the lower arm portion. The robot arm 20 is not limited to the vertical articulated robot, and may be, for example, a horizontal articulated robot device or a parallel link type robot device.

The link 20L is composed of a rigid member, for example, a link 20L corresponding to a body rotatably attached to a base and a lower arm rotatably attached to the body. A link 20L corresponding to the portion, a link 20L corresponding to the upper arm portion rotatably attached to the lower arm portion, and a link 20L corresponding to the wrist portion rotatably attached to the upper arm portion. To prepare for.

The end effector 20E (an example of a "holding mechanism") has a function of holding an object. The end effector 20E is attached to the tip of the link 20L corresponding to the wrist portion, and is configured to be able to hold the object by sandwiching the object by, for example, movable plates 20E1 and 20E2 that are opened and closed by an actuator. However, the end effector 20E is not limited to this, and for example, a negative pressure is generated in the suction pad based on a plurality of suction pads for holding the surface of the object and a control signal transmitted from the control device 10. It may be provided with an actuator that causes the object to be moved, or may hold an object by electromagnetic force.

The robot arm 20 according to the present embodiment includes a series elastic actuator 20D provided at at least one joint 20J connecting the links 20L to each other. The series elastic actuator 20D is an example of a flexible drive mechanism. "Flexible" means elastic, viscous or elastic and viscous. Elasticity refers to the property of deforming when stress is applied and returning to the original state when stress is removed, and is sometimes expressed by the term flexibility, which indicates the ease of elastic deformation. Viscosity refers to the property of generating stress that equalizes the flow velocity of a fluid. The flexible drive mechanism may include at least one of, for example, a ferrofluid, a mechanical spring, an air spring, a magnetic spring, and a vane motor to impart flexibility.

The series elastic actuator 20D is composed of, for example, a drive unit 20DA, an elastic body 20DE connected to the drive unit 20DA, and a sensor 20DS. The drive unit 20DA is composed of, for example, a servomotor. The elastic body 20DE is composed of, for example, a mechanical spring. The power output from the drive unit 20DA in the series elastic actuator 20D is transmitted to the link 20L on the output side via the elastic body 20DE and is rotated.

The sensor 20DS detects a reference position of the robot arm 20 (hereinafter referred to as “reference position”) by acquiring, for example, the displacement amount of the mechanical spring, and supplies information indicating the reference position to the control device 10. do. The reference position of the robot arm 20 may be the position of any part of the robot arm 20. The unit of the reference position may be in any form according to the mode of the part of the robot arm 20 corresponding to the reference position. For example, the reference position may be the link 20L constituting 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.

Under the above configuration, the parameters are the inertia, mass and length of the part 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. The 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 the amount of displacement 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 cushioning an impact based on viscosity and a clutch mechanism for switching power transmission. When a viscous body such as a damper mechanism having viscosity is applied, a viscosity constant is added as a parameter to the equation of motion. For example, an equation of motion is established in which the value obtained by multiplying the viscosity constant by the time change of the link angle is taken as the torque.

The link 20L other than the link 20L driven by the series elastic actuator 20D is driven by, for example, a drive unit 20A composed of a servomotor. The drive unit 20A rotates the link 20L on the output side around the drive shaft. The drive unit 20A may be built in the link 20L. With the above configuration, it is possible to rotate the plurality of links 20L, so that the position of the end effector 20E corresponding to the tip of the link 20L can be changed. The information indicating the position in the present disclosure may include information indicating the posture when it is reasonably considered necessary.

As shown in FIG. 1, for example, the control device 10 includes a start position acquisition unit 10A, a target position acquisition unit 10B, a planned route acquisition unit 10C, an allowable range acquisition unit 10D, a control command acquisition unit 10E, and a separation parameter calculation. A unit 10F, a distance determination unit 10G, and an allowable range determination unit 10H are provided.

The start position acquisition unit 10A acquires, for example, the start position input from the teaching device 50 connected to the control device 10. Here, the "start position" may be the start position of the reference position of the robot arm 20 in the movement of the robot arm 20. The start position acquisition unit 10A acquires, for example, the start position input from the teaching device 50 connected to the control device 10. The teaching device 50 may be a teaching device 50 that follows online teaching in which the robot arm 20 is actually moved in the field to teach the reference position as the start position, or a text type that teaches the reference position as the start position by a computer program. The teaching device 50 according to offline teaching such as a simulator type, an emulator type, or an automatic teaching type may be used.

The target position acquisition unit 10B acquires, for example, the target position input from the teaching device 50. Here, the "target position" may be the final target position of the reference position of the robot arm 20 in the movement of the robot arm 20. The unit of the target position may be any format according to the reference position. For example, when the reference position of the robot arm 20 is the link 20L constituting the robot arm 20, the target position can be expressed as angle information. For example, when the reference position of the robot arm 20 is the hand position (for example, the center point of the end effector 20E), the target position can be expressed as three-dimensional position information.

The planned route acquisition unit 10C acquires, for example, the planned route input from the teaching device 50. Here, the "planned path" may be a target path from the start position of the reference position of the robot arm 20 to the target position in the movement of the robot arm 20. At least one point included in the "planned route" may be associated with the estimated time of arrival, which is the time when the reference position of the robot arm 20 is scheduled to arrive at the at least one point. In particular, the planned route may include the estimated time of arrival associated with the above-mentioned target position (the final target position of the reference position of the robot arm 20).

The permissible range acquisition unit 10D acquires, for example, the permissible range input from the teaching device 50. Here, the "allowable range" is a predetermined range based on the planned path, even if the reference position of the robot arm 20 is allowed to be separated from the planned path in the movement of the robot arm 20. good. The method of controlling the operation of the robot arm in each of the cases where the reference position of the robot arm is included in the permissible range and the case where the reference position is not included in the permissible range can be arbitrarily set. For example, if it is not included in the permissible range, the robot arm may be controlled so as to be included in the permissible range (for example, to approach a predetermined route such as a planned route).

Here, when the reference position of the robot arm 20 is far from the target position, the accuracy required for the movement of the robot arm 20 is often acceptable even if it is relatively low. On the other hand, when the reference position of the robot arm 20 is close to the target position, it can be said that relatively high accuracy is required for the movement of the robot arm 20. Therefore, in the robot system 100 according to the present embodiment, "permissible" is based on a predetermined parameter (hereinafter, may be referred to as "separation parameter") indicating the degree of separation between the reference position and the target position of the robot arm 20. The range may be specified.

As a first example, the separation parameter may be, for example, the difference between the target position (the final target position of the reference position of the robot arm 20 in the movement of the robot arm 20) and the reference position of the robot arm 20. good. In this case, the unit of the separation parameter may be in any form according to the target position and the reference position. For example, when the reference position of the robot arm 20 is the link 20L constituting the robot arm 20, the separation parameter may be expressed as the angle information according to the target position and the reference position being expressed as the angle information. Further, for example, when the reference position of the robot arm 20 is the hand position (for example, the center point of the end effector 20E), the separation parameter is also the angle information according to the fact that the target position and the reference position are each expressed as three-dimensional position information. It may be expressed as. As a second example, the separation parameter may be, for example, the difference between the estimated time of arrival associated with the target position in the planned route and the current time. In this case, the unit of the separation parameter may be expressed as time.

As described above, in the robot system 100 according to the present embodiment, the "allowable range" may be set based on the separation parameter. For example, when the separation parameter is equal to or greater than a predetermined threshold value, a “first allowable range” may be set for the movement of the robot arm 20. Further, when the separation parameter is less than a predetermined threshold value, a "second allowable range" may be set for the movement of the robot arm 20. Here, "first permissible range> second permissible range" may be satisfied.

Here, the allowable range will be described with reference to FIG. In the figure, a graph is shown in which the horizontal axis is time and the vertical axis is the reference position of the robot arm 20. In the figure, as an example, it is assumed that the reference position of the robot arm 20 is set to the angle of the link 20L driven by the series elastic actuator 20D. The curve with the reference numeral P is a planned path for the reference position of the robot arm 20. The planned route P is defined so that the angle gradually increases with time from the start position S of the angle α1 at the target time t1 to the target position G of the angle α3 at the estimated arrival time t3. Further, the planned route P may include a statically determinate period from time t3 to time t4. The curve with reference numeral A shows an example of the actual locus of the reference position of the robot arm 20 (the angle of the link 20L driven by the series elastic actuator 20D).

For example, when the separation parameter is set as the difference between the target position G (angle α3) and the reference position of the robot arm 20 as in the first example described above, the threshold value Ca for the separation parameter is predetermined with the target position G. It may be specified as a difference from the position. In this case, for example, assuming that the predetermined position is the position T associated with the angle α2 and the time t2 in FIG. 4, the threshold value Ca is defined as “Ca = α3-α2”. The position T is not particularly limited and can be set arbitrarily.

For example, when the separation parameter is set as the difference between the estimated arrival time t3 associated with the target position G in the planned route and the current time as in the second example described above, the threshold Ct for the separation parameter is the target. It may be defined as the difference between the estimated time of arrival t3 associated with the position G and the estimated time of arrival associated with the predetermined position. In this case, for example, assuming that the predetermined position is the position T associated with the angle α2 and the time t2 in FIG. 4, the threshold value Ct is defined as “Ct = t3-t2”. The position T is not particularly limited and can be set arbitrarily.

In FIG. 4, the reference position of the robot arm 20 is centered on the planned path P in a range of the angle α1 or more of the start position S and a predetermined angle α2 or less (a range after the time t1 and before the predetermined time t2). The first permissible range is set in the range of ± β1. Further, in the range where the reference position of the robot arm 20 is larger than the angle α2 and the angle α3 or less of the target position G (the range after the time t2 and before the time t3), the range of ± β2 centered on the planned path P. The second permissible range is set in. Here, it is assumed that β1> β2.

In the graph A shown in FIG. 4, at time t11, the reference position of the robot arm 20 is at an angle exceeding the first permissible range. In this case, the control device 10 moves the robot arm 20 so that the reference position of the robot arm 20 is arranged within the first allowable range with respect to the planned path P. For example, the control device 10 reduces the rotation speed of the link 20L and the movement speed of the object, and controls the angle of the link 20L so as to be within the first permissible range. Similarly, when the reference position of the robot arm 20 is at an angle exceeding the second allowable range, the control device 10 similarly has the control device 10 in which the reference position of the robot arm 20 is within the second allowable range with respect to the planned path P. The robot arm 20 may be moved so as to be arranged in.

Each of β1 and β2 described above is information in an angle unit that can be preset as a range in which elastic deformation is possible based on the spring constant of the elastic body 20DE of the series elastic actuator 20D. When the robot arm 20 is provided with a plurality of series elastic actuators 20D in order to have flexibility in a plurality of directions, a permissible range (first permissible range and second permissible range) is provided for each of the plurality of links 20L driven by the series elastic actuator 20D. A set with an allowable range) may be set.

In FIG. 4, the upper limit width (+ β1 and + β2) and the lower limit width (-β1 and -β2) based on the planned route P are the same for both the first allowable range and the second allowable range. Explained as being. However, the upper limit width (upper limit value) and the lower limit width (lower limit value) may be different. In this case, "the first allowable range is larger than the second allowable range" means that "the sum of the upper limit width and the lower limit width of the first allowable range (difference between the upper limit value and the lower limit value) is the upper limit of the second allowable range". It can be read as "greater than the sum of the width and the lower limit width (difference between the upper limit value and the lower limit value)".

In FIG. 4, a case where only two allowable ranges (first allowable range and second allowable range) are set for one reference position of the robot arm 20 has been described as an example. However, the number of allowable ranges is not limited to two, and may be three or more. In that case, the size of each permissible range may be different depending on the size of the separation parameter described above. For example, each allowable range may be set so that the allowable range increases as the separation parameter increases (the reference position of the robot arm 20 separates from the target position).

The information indicating the permissible range (first permissible range, second permissible range, etc.) is defined in advance as a constant based on the elasticity or viscosity of the drive mechanism in the computer program stored in the non-volatile storage element described later. Can be done. Therefore, the information indicating the permissible range may be acquired by reading the computer program from the arithmetic element of the control device 10. Alternatively, the control device 10 may acquire information indicating an allowable range from the teaching device 50.

Return to FIGS. 1, 2A, and 2B. The control command acquisition unit 10E acquires a control command for moving the reference position of the robot arm 20 according to the planned route acquired by the planned route acquisition unit 10C by arithmetic processing or the like. For example, the control command acquisition unit 10E calculates the rotation angle of each servomotor for the reference position to be located on the planned path by inverse kinematics calculation (inverse kinematics), and generates a control command based on this. Therefore, it can be stored in a non-volatile storage element. The content of the control command may differ depending on whether or not the reference position of the robot arm 20 is within the allowable range (first allowable range, second allowable range, etc.) with respect to the planned path. For example, when it is determined that the robot arm 20 is out of the permissible range (first permissible range, second permissible range, etc.) with respect to the planned route, the control command indicates that the reference position of the robot arm 20 is within the permissible range (first permissible range and second permissible range, etc.). The robot arm 20 may be moved so as to be arranged within the second permissible range, etc.).

The separation parameter calculation unit 10F calculates the above-mentioned separation parameter (a predetermined parameter indicating the degree of separation between the reference position of the robot arm 20 and the target position). For example, when the separation parameter is defined as the difference between the target position and the reference position of the robot arm 20, the separation parameter calculation unit 10F is supplied by the target position acquired by the target position acquisition unit 10B and the sensor 20DS of the robot arm 20. The difference from the reference position is calculated as a separation parameter. Further, for example, when the separation parameter is defined as the difference between the scheduled arrival time associated with the target position and the current time in the planned route, the separation parameter calculation unit 10F sets the planned route acquired by the planned route acquisition unit 10C. The difference between the estimated arrival time associated with the included target position (the time when the reference position of the robot arm 20 is scheduled to arrive at the target position) and the current time supplied from an internal clock (not shown), for example, is a separation parameter. Calculated as.

The separation determination unit 10G determines, for example, the degree of separation between the reference position and the target position of the robot arm 20 based on the separation parameter. Specifically, the separation determination unit 10G compares the separation parameter calculated by the separation parameter calculation unit 10F with a predetermined threshold value. Here, the predetermined threshold value may be a threshold value for partitioning an allowable range for movement of the robot arm 20, as in the threshold value C described with reference to FIG. 4, and is stored in the non-volatile storage element. May be. A plurality of predetermined threshold values may be set, and the size of the allowable range may be set differently before and after each threshold value accordingly. In particular, the larger the separation parameter (that is, the more the reference position of the robot arm 20 is separated from the target position), the larger the allowable range may be set. That is, the smaller the separation parameter (that is, the closer the reference position of the robot arm 20 is to the target position), the smaller the allowable range may be set.

The permissible range determination unit 10H determines, for example, whether or not the reference position of the robot arm 20 is within the permissible range (first permissible range, second permissible range, etc.) with respect to the planned path. Specifically, the permissible range determination unit 10H calculates the difference between the reference position supplied by the sensor 20DS of the robot arm 20 and the planned path, and then the difference is the permissible range (first permissible range and second permissible range). It is determined whether or not it is within the range, etc.).

Regarding the hardware configuration, the control device 10 includes, for example, an arithmetic element which is a processor such as a CPU (Central Processing Unit) and a GPU (Graphical Processing Unit), a SRAM (Static Random Access Memory), a DRAM (Dynamic Memory), and the like. It is possible to configure a computer equipped with a volatile storage element of the above, a non-volatile storage element such as a NOR flash memory, a NAND flash memory, and an HDD (Hard Disc Drive), and a communication means such as a bus connecting these. The non-volatile storage element stores, for example, a computer program (including data such as information indicating an allowable range) for executing each process shown in the present embodiment. The volatile storage element temporarily stores at least a part of these computer programs, arithmetic processing results, and the like. However, at least a part of these arithmetic elements, non-volatile storage elements and the like may be installed in a remote place connected to a communication network such as the Internet. For example, the arithmetic element may be configured to acquire a computer program or necessary data via a communication network.

The control device 10 and the robot arm 20 are configured to be capable of transmitting and receiving information by wireless or wired communication means.

A teaching device 50 for teaching the operation to the robot system 100 may be connected to the control device 10. The teaching device 50 includes, for example, a portable teaching pendant for performing online teaching. Like the control device 10, the teaching device 50 includes an arithmetic element, a volatile memory element, and a non-volatile memory element, and further includes a display means having a display and an input means having a plurality of operation keys and levers. The input means may be composed of a touch panel type input means for inputting by pressing the display.

FIG. 5 is a flowchart showing a process for teaching the operation to the robot system 100.

As shown in the figure, the operator teaches the robot system 100 the start position by moving the end effector 20E manually or by using the input means of the teaching device 50 (step S41). For example, the position where the end effector 20E starts holding the object may be set as the start position. The control device 10 acquires the position of the end effector 20E when it exists at the start position, the angle of each link 20L, and the like, associates it with the start position, and stores it in the non-volatile storage element (step S42).

Further, the operator teaches an operation for holding the object to the end effector 20E (step S43), and the control device 10 stores the operation for holding the object in the non-volatile storage element (step S44). ).

Next, the operator moves the end effector 20E a plurality of times manually or by using the input means of the teaching device 50, and causes the control device 10 to acquire the position and the like of the end effector 20E at that time, whereby the robot system 100 (Step S45). Here, for the scene where the object comes into contact with the object, the position of the end effector 20E such that the object interferes with the object as shown in FIGS. 3A and 3B is taught as the target position.

The control device 10 acquires the position of the end effector 20E and the angle of each link 20L when they are present at the target position, associates them with each target position, and stores them in the storage element (step S46).

Next, the control device 10 acquires information indicating the first permissible range and the second permissible range (step S47). Here, the first permissible range is set for the movement of the robot arm 20 when the separation parameter, which is a predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm 20, is equal to or more than a predetermined threshold value. It may be within the allowable range. That is, the first permissible range is, for example, the range of ± β1 centered on the planned path P in the range of the angle α1 or more and the angle α2 or less (the range after the time t1 and before the time t2) shown in FIG. good. Further, the second permissible range may be a permissible range smaller than the first permissible range and may be a permissible range set for the movement of the robot arm 20 when the separation parameter is less than a predetermined threshold value. When the separation parameter is less than a predetermined threshold value, a "second allowable range" may be set for the movement of the robot arm 20. That is, the second permissible range is, for example, in the range of ± β2 centered on the planned path P in the range larger than the angle α2 and less than the angle α3 (the range after the time t2 and before the time t3) shown in FIG. It may be there.

The control device 10 acquires a planned route connecting the start position and the target position by an operation according to a route generation algorithm. The control device 10 causes the object to interfere with the object in a region where the object imitates the object, for example, from the target position in the scene of FIG. 3A to the target position in the scene of FIG. 3B. The route to be used is obtained by calculation. By acquiring the planned route in this way, it becomes possible to imitate the object with respect to the object.

However, if the displacement amount is too large, it may exceed the range of elastic deformation. Further, even within the range of elastic deformation, if the displacement amount is too large, the force with which the object presses the object becomes too large, which makes smooth movement difficult or damages the object or the object. there's a possibility that. Therefore, the control device 10 calculates the planned route so that the distance between the route and the surface of the target object is within the allowable range (step S48).

After that, the control device 10 may store the acquired planned path in the non-volatile storage element. Specifically, the control command acquisition unit 10E of the control device 10 issues a control command for controlling each drive unit of the robot arm 20 and the drive unit of the series elastic actuator 20D based on the acquired target position and planned path. It may be acquired by calculation and stored in the non-volatile storage element.

Subsequently, the operation method of the robot system 100 will be described. FIG. 6 is a flowchart showing an operation method of the robot system 100.

First, the start position acquisition unit 10A and the target position acquisition unit 10B of the control device 10 acquire information indicating the start position and information indicating the target position, respectively (step S71). The control device 10 may acquire this information by reading it from the non-volatile storage element. The control device 10 may acquire these information from the teaching device 50.

Further, the permissible range acquisition unit 10D of the control device 10 acquires information and the like indicating the first permissible range and the second permissible range (step S72). The control device 10 may acquire this information by reading it from the non-volatile storage element. Alternatively, when the control device 10 acquires the planned route by calculation based on the information indicating the start position and the information indicating the target position, the distance between the object surface and the reference position is within the permissible range (first permissible range and first). (2) By reading a route generation algorithm that falls within the permissible range (2) and acquiring a planned route based on the algorithm, information indicating the permissible range (first permissible range and second permissible range) may be acquired.

The planned route acquisition unit 10C of the control device 10 reads out a route generation algorithm from the non-volatile storage element so that the distance between the object surface and the reference position is within the allowable range, and connects the start position and the target position based on this. The planned route to be performed is acquired by calculation (step S73). The control command acquisition unit 10E acquires a control command for controlling each drive unit of the robot arm 20 and the drive unit of the series elastic actuator 20D by calculation based on the acquired target position, planned path, and the like (step S74). ..

When the control command for controlling the drive unit and the actuator of the end effector 20E for realizing a series of operations is stored in the non-volatile storage element, the control device 10 controls to reflect the start position information and the like. These information may be acquired by reading the instruction.

Next, the robot arm 20 drives each link 20L based on the control command received from the control device 10. First, at the start position, the end effector 20E of the robot arm 20 holds the object (step S75).

After that, the robot arm 20 moves the object and brings it closer to the object (step S76). Then, the robot arm 20 brings the end portion of the object into contact with the surface of the object (step S77).

The robot arm 20 causes the object to imitate the object by moving the object relative to the object while maintaining the state where the end of the object is in contact with the surface of the object. (Step S78). For example, as shown in FIG. 3A, the robot arm 20 may translate the object relative to the object, and as shown in FIG. 3B, the robot arm 20 may move the object relative to the object. The object may be relatively rotationally moved. At this time, the control device 10 controls the robot arm 20 so that the reference position of the robot arm 20 is arranged within the first permissible range or the second permissible range with respect to the planned path according to the magnitude of the separation parameter. To move. When the reference position of the robot arm 20 reaches the target position by the movement process, for example, when the object is fitted to the target object, the operation process ends.

Next, with reference to FIG. 7, the operation method of the movement process in the above-mentioned step S78 will be described.

First, the separation parameter calculation unit 10F calculates a separation parameter, which is a predetermined parameter indicating the degree of separation between the reference position and the target position of the robot arm 20 (S81). For example, when the separation parameter is defined as the difference between the reference position and the target position of the robot arm 20, the separation parameter calculation unit 10F is acquired by the reference position and the target position acquisition unit 10B supplied by the sensor 20DS of the robot arm 20. The difference from the target position is calculated as a separation parameter. Further, for example, when the separation parameter is defined as the difference between the current time and the target time associated with the target position, the separation parameter calculation unit 10F is the target time included in the planned route acquired by the planning route acquisition unit 10C. The difference between (the time associated with the target position) and the current time supplied from, for example, an internal clock (not shown) is calculated as a separation parameter.

Next, the separation determination unit 10G determines whether or not the “separation parameter <threshold value” is satisfied (S82). Here, the threshold value may be a threshold value for partitioning an allowable range for movement of the robot arm 20 stored in the non-volatile storage element. Specifically, the threshold value may be, for example, the threshold value C shown in FIG.

When it is determined in step S82 that the "separation parameter <threshold value" is not satisfied (S82; No), the allowable range determination unit 10H determines whether or not the "reference position of the robot arm 20 ≤ first allowable range" is satisfied. Judgment (S83). Then, when it is determined that the "reference position of the robot arm 20 ≤ first allowable range" is satisfied (S83; Yes), for example, the reference position of the robot arm 20 is moved toward the target position according to the planned path (S83; Yes). S84). On the other hand, when it is determined that the "reference position of the robot arm 20 ≤ first allowable range" is not satisfied (S83; No), a predetermined movement process is executed (S85). The movement process may be a control (an example of the "first movement step") of moving the reference position of the robot arm 20 so that the reference position of the robot arm 20 is arranged within the first allowable range. At the same time, the reference position of the robot arm 20 may be moved toward the target position according to the planned path.

When it is determined in step S82 that the "separation parameter <threshold value" is satisfied (S82; Yes), the allowable range determination unit 10H determines whether or not the "reference position of the robot arm ≤ second allowable range" is satisfied. (S86). Then, when it is determined that the "reference position of the robot arm 20 ≦ the second allowable range" is satisfied (S86; Yes), for example, the reference position of the robot arm 20 is moved toward the target position according to the planned path (S86; Yes). S87). On the other hand, when it is determined that the "reference position of the robot arm 20 ≦ the second allowable range" is not satisfied (S86; No), a predetermined movement process is executed (S88). The movement process may be a control (an example of a "second movement step") of moving the reference position of the robot arm 20 so that the reference position of the robot arm 20 is arranged within the second allowable range. At the same time, the reference position of the robot arm 20 may be moved toward the target position according to the planned path.

Next, the separation determination unit 10G determines whether or not the reference position of the robot arm 20 has reached the target position (S89). When it is determined that the reference position of the robot arm 20 has reached the target position (S89; Yes), the operation process ends. At this time, the robot arm 20 may release the holding of the object. On the other hand, when it is determined that the reference position of the robot arm 20 has not reached the target position (S89; No), the operation process returns to step S81.

As described above, according to the operation method according to the present embodiment, when the predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than the predetermined threshold value, the reference position is relative to the planned path. It is possible to move the robot arm so that it is placed within the first permissible range, and if the predetermined parameter is less than the predetermined threshold value, the reference position is placed within the second permissible range with respect to the planned path. It is possible to move the robot arm so that it is done. Therefore, it is possible to appropriately set the allowable range for the movement of the robot arm.

In addition to the fitting operation, the present invention holds a flange (an example of an "object") on which a through hole is formed, and a shaft (“objective”) on the wall surface of the through hole so that the shaft penetrates the through hole. Following the surface of "object" and "assembly site"), the work of assembling the flange to the shaft and holding the printed wiring board to be inspected (example of "object") are formed on the printed wiring board. The inner diameter of the through hole is inspected by tracing the wall surface of the through hole to the surface of the inspection instrument so that the rod-shaped inspection instrument (an example of "object" and "assembly site") penetrates the through hole. It can be applied to various applications such as work and work of assembling an optical component such as a lens module (an example of an "object") to a precision instrument (an example of an "object" and an "assembly site"). .. The “assembly site” is not limited to a member to which an object is attached and fixed, but also includes a member having a temporary engagement relationship with the object. For example, as in the above example, the robot arm performs an inspection by imitating the surface of the inspection instrument, which is the assembly site, with the printed wiring board, which is the object, and then holds the printed wiring board as the inspection instrument. May be disengaged and moved to another position. As a flexible drive mechanism, various drive mechanisms can be used in addition to the series elastic actuator. Magnetic fluids, mechanical springs (leaf springs, torsion coil springs), air springs, magnetic force springs, vane motors, variable dampers using electric viscous fluids whose viscosity can be adjusted according to the applied voltage, to impart viscosity and elasticity. Etc. may be used.

In the above-described embodiment, the second allowable range when the separation parameter is less than the predetermined threshold value is smaller than the first allowable range when the separation parameter is equal to or more than the predetermined threshold value. However, the present invention is not limited to this, and the second allowable range when the separation parameter is less than the predetermined threshold value may be larger than the first allowable range when the separation parameter is equal to or more than the predetermined threshold value. For example, when the movement of the robot arm at a position relatively far from the target position is more restricted due to an obstacle or the like up to the target point, the allowable range for the movement of the robot arm is increased by the configuration. Can be set appropriately.

Further, the present invention can be modified in various ways as long as it does not deviate from the gist thereof. For example, some components in one embodiment may be added to other embodiments within the normal creative abilities of those skilled in the art. Also, some components in one embodiment can be replaced with corresponding components in another embodiment.

10 Control device 10A Start position acquisition unit 10B Target position acquisition unit 10C Planned route acquisition unit 10D Allowable range acquisition unit 10E Control command acquisition unit 10F Separation parameter calculation unit 10G Separation determination unit 10H Allowance range determination unit 20 Robot arm 20A Drive unit 20E End Effector 20E1 Movable plate, 20E2 Movable plate 20D Series elastic actuator 20DA Drive unit 20DE Elastic body 20DS Sensor 20J Joint 20L Link 50 Teaching device 100 Robot system

Claims (11)

Steps to get information that shows the planned route to the target position,
An acquisition step for acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range.
When a predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than a predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. The first movement step of moving the robot arm and
When the predetermined parameter is less than the predetermined threshold value, the robot arm is moved so that the reference position is arranged within the second allowable range smaller than the first allowable range with respect to the planned path. Operation method including 2 movement steps. The operation method according to claim 1, wherein the predetermined parameter is a difference between the target position and the reference position. The operation method according to claim 2, wherein the difference is angle information or position information. The operation method according to claim 1, wherein the predetermined parameter is a difference between the estimated arrival time associated with the target position in the planned route and the current time. The operation method according to any one of claims 1 to 4, wherein the first movement step and / or the second movement step reduces the speed of the reference position of the robot arm. The operation method according to any one of claims 1 to 5, wherein the robot arm includes a flexible drive mechanism. The operation method according to claim 6, wherein the robot arm further includes a holding mechanism capable of holding an object. With the robot arm
A robot system including a control device for controlling the robot arm.
The control device is
A means of acquiring information indicating the planned route to the target position,
An acquisition means for acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range.
When a predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than a predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. The first moving means for moving the robot arm and
When the predetermined parameter is less than the predetermined threshold value, the robot arm is provided with a second moving means for moving the robot arm so that the reference position is arranged within the second allowable range with respect to the planned path. , Robot system. A control device that controls the robot arm
A means of acquiring information indicating the planned route to the target position,
An acquisition means for acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range.
When a predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than a predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. The first moving means for moving the robot arm and
When the predetermined parameter is less than the predetermined threshold value, the robot arm is provided with a second moving means for moving the robot arm so that the reference position is arranged within the second allowable range with respect to the planned path. ,Control device. With the robot arm
It is a teaching method for teaching an operation to a robot system including a control device for controlling the robot arm.
Steps to get information that shows the planned route to the target position,
An acquisition step for acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range.
When a predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than a predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. The first movement step of moving the robot arm and
When the predetermined parameter is less than the predetermined threshold value, a second movement step of moving the robot arm so that the reference position is arranged within the second allowable range with respect to the planned path, and a second movement step.
A teaching method for teaching the robot system to execute the above. On the computer
Steps to get information that shows the planned route to the target position,
An acquisition step for acquiring information indicating a first allowable range and information indicating a second allowable range smaller than the first allowable range.
When a predetermined parameter indicating the degree of separation between the reference position of the robot arm and the target position is equal to or more than a predetermined threshold value, the reference position is arranged within the first allowable range with respect to the planned path. The first movement step of moving the robot arm and
When the predetermined parameter is less than the predetermined threshold value, the second movement step of moving the robot arm so that the reference position is arranged within the second allowable range with respect to the planned path is executed. A computer program to let you.

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