KR102170591B1 - Friction Compensation Method for Multi-DOF Cooperative Robots - Google Patents

Abstract

The present invention relates to a friction compensation method of a multi-degree of freedom cooperative robot. The friction compensation method of the multi-degree of freedom cooperative robot according to an embodiment of the present invention, as a friction compensation method of a multi-degree of freedom cooperative robot including a plurality of joints, comprises the following steps of: generating a motion of the cooperative robot for friction compensation; driving the plurality of joints based on the generated motion of the cooperative robot; receiving friction identification data from the cooperative robot; and calculating a friction model function from the received friction identification data. According to the present invention, the cooperative robot can measure a friction force, collect a large amount of friction force data, and derive a friction model without intervention of a user.

Description

Friction Compensation Method for Multi-DOF Cooperative Robots}

The present invention relates to a method for compensating friction of a cooperative robot with multiple degrees of freedom, and more particularly, to a method for compensating a friction force acting on a cooperative robot having multiple degrees of freedom.

Recently, cooperative robots that can work in the same space as humans have emerged. The cooperative robot is a robot that operates in close proximity to a person, and is manufactured to operate at a slower speed and smaller than that of a conventional industrial robot for the safety of humans.

The collaborative robot has the advantage that the operator can directly teach and use it if necessary.

However, the agile interaction between the user and the cooperative robot is hindered in a situation where the user directly moves the cooperative robot and teaches directly due to the large frictional force generated by the gear mechanism existing at each joint of the cooperative robot.

In addition, even if the setting according to the frictional force compensation is completed during the initial setting of the cooperative robot, the friction characteristics change due to the wear of the drive system according to the use period of the cooperative robot. Often, the driving precision is poor.

The problem to be solved by the present invention is to provide a friction compensation method of a cooperative robot with a degree of freedom in which a cooperative robot can measure friction by itself, collect a large amount of friction force data, and derive a friction model without user intervention.

The problems of the present invention are not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In the friction compensation method of a multi-degree of freedom cooperative robot according to an embodiment of the present invention for solving the above problems, in the friction compensation method of a multi-degree of freedom cooperative robot including a plurality of joints, the motion of the cooperative robot for friction compensation Generating, driving the plurality of joints based on the generated motion of the cooperative robot, receiving friction identification data from the cooperative robot, and calculating a friction model function from the received friction identification data Includes.

In the step of generating the motion of the cooperative robot, a posture that removes the influence of gravity may be created.

In the step of generating the motion of the cooperative robot, a motion for removing an inertial effect may be generated.

In the step of generating the motion of the cooperative robot, a motion to remove the influence of the Coriolis force may be generated.

The friction identification data may include angle information of a plurality of joints, torque-related information acting on a plurality of joints, and temperature information of an actuator driving the plurality of joints.

In the step of calculating the friction model function, static friction, kinetic friction, and viscous friction acting on the plurality of joints may be identified based on the friction identification data.

Real-time data of the friction identification data may be used to identify the static friction and the kinetic friction, and average data of the friction identification data may be used to identify the viscous friction.

The variable of the friction model function may include driving speeds of the plurality of joints.

The friction identification data may include temperature information of actuators driving the plurality of joints, and a variable of the friction model function may further include the temperature information.

Driving the plurality of joints by applying the calculated friction model function; And

It may further include evaluating the friction model function based on the position error of the cooperative robot.

It may further include correcting a parameter of the friction model function based on a result of evaluating the friction model function.

Other specific details of the present invention are included in the detailed description and drawings.

According to the embodiments of the present invention, there are at least the following effects.

The cooperative robot measures the friction by itself without user intervention, collects a large amount of friction data, and derives a friction model.

In addition, since the friction model is automatically calculated and the friction force is calculated and compensated by itself, it is possible to maintain agile direct teaching and force control performance regardless of the use period of the cooperative robot.

The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is a perspective view showing a multi-degree of freedom cooperative robot.
2 is a block diagram schematically showing a friction compensation system of a multi-degree of freedom cooperative robot according to an embodiment of the present invention.
3 is a flow chart for explaining a friction compensation method of a multi-degree of freedom cooperative robot according to an embodiment of the present invention.
4 is a flowchart illustrating a friction compensation method of a multi-degree of freedom cooperative robot according to another embodiment of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and are common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims.

Further, the embodiments described in the present specification will be described with reference to sectional views and/or schematic diagrams, which are ideal exemplary diagrams of the present invention. Therefore, the shape of the exemplary diagram may be modified by manufacturing technology and/or tolerance. In addition, in each of the drawings shown in the present invention, each component may be somewhat enlarged or reduced in consideration of convenience of description. The same reference numerals refer to the same components throughout the specification.

Hereinafter, the present invention will be described with reference to drawings for explaining a friction compensation system for a multi-degree of freedom cooperative robot and a friction compensation method for a multi-degree of freedom cooperative robot according to an embodiment of the present invention.

1 is a perspective view showing a multi-degree of freedom cooperative robot.

The cooperative robot 10 includes a plurality of joints 12, 13, 14, 15, 16, 17 to realize a multi-degree of freedom movement. In FIG. 1, as an example of a multi-degree of freedom cooperative robot, a cooperative robot 10 configured to have 6 degrees of freedom using six joints 12, 13, 14, 15, 16, 17 is shown.

The first joint 12 is rotatably coupled to the upper portion of the base 11, and the first joint 12 rotates about the Z-axis (vertical direction based on FIG. 1). One end surface (a surface facing the base 11) and the other end surface (a surface facing the second joint 13) of the first joint 12 are positioned on a plane perpendicular to each other.

The second joint 13 is rotatably coupled to the other end of the first joint 12. Since one end surface and the other end surface of the first joint 12 are located on a plane perpendicular to each other, the second joint 13 rotates about an axis in a vertical direction with respect to the rotation axis of the first joint 12. One end surface of the second joint 13 (a surface facing the first joint 12) and the other end surface (a surface facing the third joint 14) are positioned on a plane parallel or coincident with each other.

The third joint 14 is rotatably coupled to the other end of the second joint 13. Since one end surface and the other end surface of the second joint 13 are positioned on a plane parallel or coincident with each other, the third joint 14 rotates about an axis parallel to the rotation axis of the second joint 13. One end surface of the third joint 14 (a surface facing the second joint 13) and the other end surface (a surface facing the fourth joint 15) are located on a plane perpendicular to each other.

The fourth joint 15 is rotatably coupled to the other end of the third joint 14. Since one end surface and the other end surface of the third joint 14 are located on a plane perpendicular to each other, the fourth joint 15 rotates about an axis in a vertical direction with respect to the rotation axis of the third joint 14. One end surface of the fourth joint 15 (the surface facing the third joint 14) and the other end surface (the surface facing the fifth joint 16) are located on a plane perpendicular to each other.

The fifth joint 16 is rotatably coupled to the other end of the fourth joint 15. Since one end surface and the other end surface of the fourth joint 15 are located on a plane perpendicular to each other, the fifth joint 16 rotates about an axis in a vertical direction with respect to the rotation axis of the fourth joint 15. One end surface (the surface facing the fourth joint 15) and the other end surface (the surface facing the sixth joint 17) of the fifth joint 16 are located on a plane perpendicular to each other.

The sixth joint 17 is rotatably coupled to the other end of the fifth joint 16. Since one end surface and the other end surface of the fifth joint 16 are positioned on a plane perpendicular to each other, the sixth joint 17 rotates about an axis in a vertical direction with respect to the rotation axis of the fifth joint 16. One end surface (a surface facing the fourth joint 15) and the other end surface of the fifth joint 16 are located on a plane perpendicular to each other.

An end tool (not shown) is mounted on the other end of the sixth joint 17. There are various types of end tools according to tasks performed by the cooperative robot 10, and the other end of the sixth joint 17 is configured to replace and mount various end tools.

Each joint (12, 13, 14, 15, 16, 17) is provided with an actuator (not shown) that drives the joints (12, 13, 14, 15, 16, 17) to rotate.

In order to improve the driving precision of the cooperative robot 10 and maintain and use convenience, the frictional force acting on each joint (12, 13, 14, 15, 16, 17) of the cooperative robot 10 is grasped, and loss due to the frictional force A frictional force compensation control is needed to control the actuator in consideration of the resulting torque.

2 is a block diagram schematically showing a friction compensation system of a multi-degree of freedom cooperative robot according to an embodiment of the present invention.

As shown in FIG. 2, the friction compensation system 1 of a multi-degree of freedom cooperative robot according to an embodiment of the present invention includes a cooperative robot 10 and a robot control unit 20 of multi-degree of freedom.

The cooperative robot 10 includes an actuator 11, an actuator control unit 12, an encoder 13 and a temperature sensor 14.

The actuator 11 is a driving source for rotationally driving the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10, as described above. The actuator control unit 12 may measure a current value supplied to the actuator 11 and calculate a driving speed and a position of the joints 12, 13, 14, 15, 16, 17. The temperature sensor 14 measures the temperature of the actuator 11. The encoder 13 measures the angle of the joints 12, 13, 14, 15, 16, 17.

The actuator 11, the actuator controller 12, the encoder 13, and the temperature sensor 14 may be provided for each of the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10, respectively.

The robot control unit 20 is communicatively connected with the cooperative robot 10, and stores the motion generation unit 21, the control unit 22, the communication unit 23, the data collection unit 24, the operation unit 25, and friction parameters. A unit 26, a friction model function evaluation unit 27, and a friction parameter correction unit 28 are included.

The motion generating unit 21 generates a motion required for the cooperative robot 10 to derive the frictional force of the cooperative robot 10.

The control unit 22 is responsible for controlling the cooperative robot 10. The control unit 22 controls the actuator 11 of the cooperative robot 10, and the cooperative robot 10 operates by accurately complying with the motion trajectory of the cooperative robot 10 generated by the motion generating unit 21. Robust position control for (10) can be performed.

The communication unit 23 manages communication between the robot control unit 20 and the cooperative robot 10. The communication unit 23 may be based on Ethernet communication, and transmits a control command from the robot control unit 20 to the cooperative robot 10, and the cooperative robot 10 from the cooperative robot 10 to the robot control unit 20 Can deliver information necessary for the control of In addition, friction identification data including angle information of a plurality of joints, torque-related information, and temperature information of an actuator from the cooperative robot 10 may be transmitted to the robot control unit 20.

The data collection unit 24 collects and classifies data related to the cooperative robot 10 (particularly, friction identification data) transmitted from the communication unit 23.

The calculation unit 25 is based on the data collected/classified by the data collection unit 24, and additional information about the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10 (for example, Speed information, location information, torque information, average value for specific information, etc.) can be calculated.

In addition, the calculation unit 25 may identify static friction, kinetic friction, and viscous friction acting on a plurality of joints based on data collected/classified by the data collection unit 24.

In addition, the calculation unit 25 may calculate a friction model function based on the data collected/classified by the data collection unit 24.

The friction parameter storage unit 26 stores the friction model function or parameters of the friction model function calculated by the calculation unit 25.

The friction model function evaluation unit 27 evaluates the appropriateness of the friction model function calculated by the calculation unit 25, and the friction parameter correction unit 28 indicates that the friction model function is not appropriate in the friction model function evaluation unit 27. If evaluated, the parameters of the friction model function are corrected.

The components of the robot control unit 20 are motion generation unit 21, control unit 22, communication unit 23, data collection unit 24, operation unit 25, friction parameter storage unit 26, friction model function evaluation unit More specific details of (27) and the friction parameter correction unit 28 will be described in detail in the description of the friction compensation method of the multi-degree of freedom cooperative robot to be described later.

The components of the robot control unit 20 are motion generation unit 21, control unit 22, communication unit 23, data collection unit 24, operation unit 25, friction parameter storage unit 26, friction model function evaluation unit (27) and the friction parameter correction unit 28 are classified on the basis of function, and in an actual physical configuration, a plurality of configurations may be integrated into one physical part. For example, one computing device may perform the functions of the calculation unit 25, the friction model function evaluation unit 27, and the friction parameter correction unit 28.

3 is a flowchart illustrating a friction compensation method of a multi-degree of freedom cooperative robot according to an embodiment of the present invention.

As shown in Figure 3, the friction compensation method of the multi-degree of freedom cooperative robot according to an embodiment of the present invention, generating a motion of the cooperative robot (S11), driving the cooperative robot based on the generated motion Step (S12), receiving friction identification data (S13), calculating a friction model function (S14), applying a friction model function to driving a cooperative robot (S15), evaluating a friction model function (S16), correcting the parameter of the friction model function (S17), and updating the parameter of the friction model function (S18).

In the step of generating the motion of the cooperative robot (S11), the motion generation unit 21 generates a motion of the cooperative robot 10 for friction compensation.

The motion generating unit 21 generates a motion of the cooperative robot 10 based on the following robot dynamics equation (Equation 1) so that the cooperative robot 10 can measure the friction force by itself without user intervention.

[Equation 1]

은 각각 로봇(10)의 회전위치, 회전속도, 회전각속도를 나타낸다. 또한

은 로봇(10)의 관성력,

은 코리올리힘,

은 중력을 나타내며,

는 각각 로봇(10)에 입력되는 토크 값 및 로봇(10)에 작용하는 마찰력을 나타낸다.

Represents the rotational position, rotational speed, and rotational angular speed of the robot 10, respectively. In addition

The inertial force of the silver robot 10,

Silver Coriolis,

Represents gravity,

Represents a torque value input to the robot 10 and a friction force acting on the robot 10, respectively.

)으로 로봇(10)이 스스로 마찰력을 측정할 수 있도록 관성력, 코리올리힘 및 중력의 영향을 제거할 수 있는 로봇 모션을 각각 생성한다.The motion generating unit 21 is a torque input value (

), so that the robot 10 can measure the friction force by itself, each robot motion capable of removing the effects of inertia force, Coriolis force, and gravity is generated.

First, a description will be given of a gravity-compensated motion capable of removing the influence of gravity.

The motion generating unit 21 sets the posture of the cooperative robot 10 so that the joints 12, 13, 14, 15, 16, and 17 for which the friction force is to be measured are not affected by gravity. In this case, the cooperative robot 10 may have an overall posture parallel to a direction in which gravity acts. For example, the rotation axis of each joint may be positioned parallel to the direction in which gravity acts, so that the effect of gravity acting on each joint may be excluded. However, among the joints 12, 13, 14, 15, 16, 17, a gravity compensation motion for a joint in which the rotation axis cannot be parallel to gravity, such as the second joint 13, will be described later.

When described based on the cooperative robot 10 shown in FIG. 1,

In the case of the first joint (12), the third joint (14), the fourth joint (15) and the sixth joint (17), all joints (12, 13, 14, 15, 16, 17) have an angle of 0 degrees. Measure the friction force in the posture.

In the case of the fifth joint 16, the first joint 12, the second joint 13, the fifth joint 16 and the sixth joint 17 have an angle of 0 degrees, and the third joint 14 and The fourth joint 15 measures the frictional force in a posture having an angle of 90 degrees.

Meanwhile, for a joint that is bound to be affected by gravity in any posture, a symmetrical motion that can cancel the effect of gravity is generated and the friction force is measured.

For example, the second joint 13 measures frictional force through a motion that changes from 0 degrees to 90 degrees and a motion that changes from 90 degrees to 0 degrees.

Inertia compensation motion that can remove the inertia effect will be described.

The motion generating unit 21 generates a motion of the cooperative robot 10 so that the joints 12, 13, 14, 15, 16, and 17 for which the friction force is to be measured are not affected by inertia.

For example, the motion generating unit 21 may generate a positional trajectory in which a linear trajectory and a parabolic trajectory are mixed to generate a robot motion including a linear velocity trajectory and a constant velocity trajectory. That is, the motion generating unit 21 continuously generates a motion including a constant velocity section that is not affected by the inertial force generated by the acceleration of each joint 12, 13, 14, 15, 16, 17, and the joint 12 , 13, 14, 15, 16, 17).

We will explain the Coriolis force compensation motion that can eliminate the Coriolis force effect.

The motion generating unit 21 establishes a motion plan of the cooperative robot 10 so that the joints 12, 13, 14, 15, 16, and 17 for which the friction force is to be measured are not affected by the Coriolis force.

For example, the motion generator 21 performs a motion for sequentially driving each joint (12, 13, 14, 15, 16, 17) in order to remove the Coriolis force generated by the nonlinear multi-degree of freedom robot motion. Can be generated.

In addition, the motion generator 21 may generate a speed-based step-by-step motion in order to improve the accuracy of the friction force measurement. The speed-based step-by-step motion increases the speed at an interval of 0.05 degrees/second until a speed of 1 degree/second is reached in the first stage, and at an interval of 1 degree/second until a speed of 10 degrees/second is reached in the second stage. You can increase the speed and increase the speed in 10 degrees/second increments until the maximum speed is reached in the third stage.

In the step (S12) of driving the cooperative robot based on the generated motion, the controller 22 drives the cooperative robot 10 according to the motion generated by the motion generator 21 in step S11.

In order for the cooperative robot 10 to precisely drive along the motion, the controller 22 may be configured to implement a high-speed real-time control of a 4 kHz control period based on Ethernet communication.

In addition, the control unit 22 may improve the driving precision of the cooperative robot 10 through real-time robust position control. For example, the controller 22 may control each joint (12, 13, 14, 15, 16, 17) of the cooperative robot 10 by combining the robot model-based prefeed control method and the robot state variable-based feedback control method. I can.

In the step S13 of receiving the friction identification data, the communication unit 23 receives friction identification data from the cooperative robot 10, and the data collection unit 24 collects and classifies the friction identification data from the communication unit 23. The reception of the friction identification data may be performed together with step S12, and friction identification data of each of the joints 12, 13, 14, 15, 16, and 17 is received.

The actuator control unit 12 of the cooperative robot 10 provides information on the current value supplied to the actuator 11, and the angle of each joint 12, 13, 14, 15, 16, 17 obtained from the encoder 13. The information about the temperature and the information about the temperature of the actuator 11 obtained from the temperature sensor 14 are transmitted to the robot control unit 20.

The actuator control unit 12 acts on the position, speed, and joint of the joints 12, 13, 14, 15, 16, 17 based on the information obtained from the encoder 13 and the current value supplied to the actuator 11. It is also possible to calculate the torque and the like and transmit the calculation result to the robot control unit 20.

According to an embodiment, the cooperative robot 10 further includes a torque sensor (not shown) that measures torque acting on each joint 12, 13, 14, 15, 16, 17, and torque information output from the torque sensor May be transmitted to the robot control unit 20.

The friction identification data is data used to identify the friction force acting on each joint (12, 13, 14, 15, 16, 17), and the joints (12, 13, 14, 15, 16) measured by the encoder (13) , Angle information of 17), the current value supplied to the actuator measured by the actuator controller 12, temperature information of the actuator 11 measured by the temperature sensor 14, the joint 12 calculated by the actuator controller 12, 13, 14, 15, 16, 17) location information, speed information, etc. may be included. In this case, since the current value supplied to the actuator is proportional to the torque required to operate the joints 12, 13, 14, 15, 16, 17, the current value supplied to the actuator is the joints 12, 13, 14, 15 , 16, 17) is torque-related information for estimating the torque acting on it. When a torque sensor is provided in the cooperative robot 10, the measured value of the torque sensor becomes torque-related information.

The calculation unit 25 is based on the data collected/classified by the data collection unit 24, and additional information about the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10 (for example, Speed information, location information, torque information, average value for specific information, etc.) may be calculated and transmitted to the data collection unit 24.

The data collection unit 24 may collect and store an average value of friction identification data for each joint 12, 13, 14, 15, 16, and 17 and real-time data according to a speed-based step-by-step motion.

One motion unit can be composed of stop, clockwise rotation, stop, counterclockwise rotation, and stop. Alternatively, one motion unit may be composed of stop, counterclockwise rotation, stop, clockwise rotation, and stop. In addition, clockwise rotation and counterclockwise rotation may be composed of a linear speed section and a constant speed section. Average data of friction identification data may be stored in a certain speed section, and real-time data of friction identification data may be collected and stored in a motion of a specific speed.

In the step of calculating the friction model function (S14), the calculation unit 25 may calculate the friction model function based on the data collected/classified by the data collection unit 24.

To this end, the calculation unit 25 calculates static friction, kinetic friction, and viscous friction acting on each joint 12, 13, 14, 15, 16, 17 based on the data collected/classified by the data collection unit 24. Can be identified.

For example, the calculation unit 25 may use real-time data of friction identification data to identify static friction and kinetic friction. Static friction can be identified using the maximum torque value that appears when the joint (12, 13, 14, 15, 16, 17) begins to move, and the kinetic friction is the joint (12, 13, 14, 15, 16, 17) After starting this movement, it can be identified using the torque value that appears in the low-speed section.

In addition, the calculating unit 25 may use average data (average torque related information) of friction identification data to identify viscous friction.

The calculation unit 25 may identify a friction model function of a joint representing static friction, kinetic friction, and viscous friction. The form of the friction model function may be predefined. The calculation unit 25 may identify the constant value of the friction model function by data fitting using the least squares method.

For example, the operation unit 25 derives a friction model function (f(x)=ax ² +bx+c) of a quadratic function based on the derived data, and three friction parameters (a, b, c) can be calculated. The variable x of the friction model function may be a driving speed of the joint.

The calculation unit 25 may store or update the calculated friction model function or friction parameter in the friction parameter storage unit 26.

In the step of driving the cooperative robot by applying the friction model function (S15), the control unit 22 applies the friction model function calculated by the calculation unit 25 to each joint 12, 13, 14, 15 of the cooperative robot 10. , 16, 17). When the calculation unit 25 stores the calculated friction model function or friction parameter in the friction parameter storage unit 26, the control unit 22 applies the newly updated friction model function or friction parameter to the friction parameter storage unit 26 Drive the cooperative robot 10.

The control unit 22 calculates the friction compensation force in real time by applying the parameter of the calculated friction model function. The control unit 22 calculates a friction compensation torque value by receiving real-time speed and temperature values obtained through the communication unit 23 based on the following [Equation 2], and based on this, the joints 12, 13, 14, 15, 16, 17) can be controlled.

[Equation 2]

는 비선형 마찰모델을 나타내며

는 각각 연산된 마찰력, 관절의 속도 및 온도를 나타낸다. 본 발명의 실시예에 따른 방법은 다음의 수정된 Lu-Gre 마찰모델을 활용할 수 있다.

Represents a nonlinear friction model

Represents the calculated friction force, joint speed and temperature, respectively. The method according to an embodiment of the present invention may utilize the following modified Lu-Gre friction model.

는 각각 강성상수 및 감쇠상수를 나타내며,

정지마찰력과 운동마찰력을 나타내고,

는 점성마찰 상수값들을 나타낸다.

는 속도상수값을 의미하고,

은 각각 온도와 협동 로봇에 부착되는 무게를 나타낸다.

Represents the stiffness constant and the damping constant, respectively,

It represents static and kinetic friction,

Represents the viscous friction constant values.

Means the rate constant value,

Represents the temperature and the weight attached to the cooperative robot, respectively.

In the step of evaluating the friction model function (S16), the friction model function evaluation unit 27 evaluates the friction compensation performance of the friction model function based on the passiveness and position error of the cooperative robot 10.

If the evaluation result is less than a certain criterion, a step (S17) of correcting the parameter of the friction model function is performed, and if the evaluation result is more than a certain criterion, a step (S18) of updating the parameter of the friction model function is performed.

In the step of correcting the parameter of the friction model function (S17), the friction parameter correction unit 28 adjusts the parameter of the friction model function. Rules for adjusting the parameters of the friction model function may be predefined. For example, the friction parameter correction unit 28 may determine an adjustment range of a parameter of the friction model function based on the result of the position error measured in step S16.

In the step of updating the parameters of the friction model function (S18), the friction parameter storage unit 26 is a friction model function (or friction parameter) determined to be appropriate in step S16 or a friction model function (or correction) whose parameters are corrected in step S17. Friction parameters).

)을 협동 로봇(10)의 직접 교시 및 힘제어 모드에서 마찰력 효과를 보상하는데 사용할 수 있다.Thereafter, the control unit 22 uses a positive feedback control method to use the frictional force (

) Can be used to compensate the friction force effect in the direct teaching and force control mode of the cooperative robot 10.

For example, in a situation where the user directly teaches, when the user moves the cooperative robot 10, a torque corresponding to the friction force is applied to the joints, so that the cooperative robot 10 is similar to that little frictional force acts at each joint. In the state, the user can move the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10.

In addition, since the friction characteristics change due to wear of the drive system depending on the usage period of the cooperative robot 10, even after completing the setting according to the frictional force compensation at the time of the initial setting of the cooperative robot 10, the cooperative robot 10 As the period of use of the cooperative robot 10 is increased, the driving precision or convenience of use of the cooperative robot 10 is often deteriorated, and the friction compensation system and the multi-degree of freedom cooperative robot according to an embodiment of the present invention. According to the friction compensation method, since the friction compensation function (or friction parameter) of the cooperative robot 10 can be newly updated at any time, driving precision and convenience of use of the cooperative robot 10 can be continuously maintained.

4 is a flowchart illustrating a method for compensating friction of a multi-degree of freedom cooperative robot according to another embodiment of the present invention.

The friction compensation method of the multi-degree of freedom cooperative robot according to another embodiment of the present invention is the same as the friction compensation method of the multi-degree of freedom cooperative robot shown in FIG. 3 (S11 to S18).

However, as shown in FIG. 4, in the friction compensation method of the multi-degree of freedom cooperative robot according to another embodiment of the present invention, in the step (S17) of correcting the parameter of the friction model function, the friction parameter correction unit 28 After adjusting the constant value of the model function, the process proceeds to step S15 of driving the cooperative robot by applying the friction model function again.

Therefore, in step S15, the control unit 22 drives each of the joints 12, 13, 14, 15, 16, 17 of the cooperative robot 10 by applying a friction model function whose constant value is newly adjusted, and in step S16 Based on the result, the appropriateness of the friction model function whose constant value is adjusted is judged. If the evaluation result of the friction model function is less than a certain criterion in step S16, steps S15 and S16 proceed after step S17 again, and these tasks are performed based on the evaluation result of the friction model function whose constant value is adjusted. It repeats until it becomes abnormal.

If it is determined in step S16 that the evaluation result of the friction model function is more than a certain standard, the process proceeds to step S18 and the friction parameter storage unit 26 finally stores the friction model function (or friction parameter).

Those of ordinary skill in the art to which the present invention pertains will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

1: Friction compensation system of multi-degree of freedom cooperative robot
10: Cooperative Robot 11: Base
12: first joint 13: second joint
14: third joint 15: fourth joint
16: fifth joint 17: sixth joint
20: robot control unit

Claims (11)

In the friction compensation method of a multi-degree of freedom cooperative robot including a plurality of joints,
Generating a motion of the cooperative robot for friction compensation;
Driving the plurality of joints based on the generated motion of the cooperative robot;
Receiving friction identification data from the cooperative robot; And
Comprising a friction model function from the received friction identification data; Including,
In the step of generating the motion of the cooperative robot, a gravity compensation motion for removing the gravitational effect acting on at least some of the plurality of joints, and inertial compensation for removing the inertial effect acting on at least some of the plurality of joints Motion, generating a Coriolis force compensation motion that removes a Coriolis force effect acting on at least some of the joints,
The friction identification data includes angle information of the plurality of joints, torque-related information acting on the plurality of joints, and temperature information of an actuator driving the plurality of joints,
In the step of calculating the friction model function, the friction identification data to identify static friction, kinetic friction, and viscous friction acting on the plurality of joints based on the friction identification data, and to identify the static friction and the kinetic friction Using real-time data of, and using the average data of the friction identification data to identify the viscous friction,
The variable of the friction model function includes driving speed of the plurality of joints and temperature information of the actuator. delete delete delete delete delete delete delete delete The method of claim 1,
Driving the plurality of joints by applying the calculated friction model function; And
Evaluating the friction model function based on the position error of the cooperative robot; further comprising, the friction compensation method of the multi-degree of freedom robot. The method of claim 10,
Compensating the parameter of the friction model function based on the result of evaluating the friction model function; further comprising, a friction compensation method of a multi-degree of freedom robot.

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