KR20200097896A - Apparatus and method for generating manipulator URDF file - Google Patents

Abstract

The present invention relates to an apparatus for generating a manipulator URDF file and a method thereof. The apparatus for generating the URDF file according to an embodiment of the present invention is an apparatus for generating a URDF file for manipulator simulation, which comprises: an input unit receiving the number of links of a manipulator and Denavit-Hartenberg (DH) parameter information; and a file generation unit generating the URDF file, using the input link number and DH parameter information.

Description

Manipulator URDF file generation apparatus and method {Apparatus and method for generating manipulator URDF file}

The present invention relates to an apparatus and method for generating a manipulator URDF (Universal Robotic Description Format) file, and more particularly, to an apparatus and method for generating a URDF file using DH (Denavit-Hartenberg) parameters.

In general, robots used in the industry are largely classified into manipulators and mobile robots. First, the manipulator performs functions such as picking up and moving objects with multiple arms or assembling using end-effectors, and the mobile robot autonomously avoids obstacles and follows a given path to transport objects. Perform. The manipulator robot may have joints of rotational motion or linear motion, and the motion of the connected link is determined according to the degree of freedom.

Recently, there have been many studies on the analysis and application of manipulator simulation. Through the simulation, it is possible to test the motion, mechanics, and various movements of the robot, calculate the working radius of the robot, or determine the operating state of the manipulator under the load in advance.

However, in order to perform the manipulator simulation, the URDF file must be directly produced based on the information on each specification and shape of the manipulator link and joint. The URDF file is an XML (extensible markable language) format for providing robot modeling. The URDF file contains information about the robot's intended behavior or appearance, and is used to create robot models in several commercial simulators such as V-rep or Gazebo.

However, creating URDF files to perform simulations on various manipulators takes a lot of effort and acts as a waste of time. In particular, in a situation where the utilization of manipulators is increasing, performing various simulations as quickly as possible is emerging as a very important issue as a problem directly connected to the productivity of manipulators.

Republic of Korea Patent Publication No. 10-2014-0090601 (2014.07.17) Korean Patent Registration No. 10-0738258 (2007.07.05)

An object of the present invention is to provide an apparatus for generating a URDF file that generates a URDF file capable of simulating a manipulator using only DH parameter information.

A URDF file generation apparatus according to an embodiment of the present invention is a URDF file generation apparatus for manipulator simulation, an input unit receiving the number of links of the manipulator and DH (Denavit-Hartenberg) parameter information, and the input number of links and DH parameter information It includes a file generator that creates a URDF file using.

In addition, the URDF file generation apparatus according to an embodiment of the present invention may further include a storage unit for storing the generated URDF file.

Here, the storage unit may store preset link mass information, link shape information, and parent link and child link information of the joint.

Here, the DH (Denavit-Hartenberg) parameter information is α _i (z _i axis and the angle of the z _{i + 1} axis-to-axis), a _i (z _i and z the vertical distance of the _{i + 1)} and d _i (x _i-1 The distance between the axis and the x _i axis) may be included.

Here, the file generator may generate information including link component information including center of gravity information, inertia information, and length information of the link, and joint component information including joint position information and rotation axis information.

Here, the center of gravity information may include information about an x value, a y value, and a z value, which are the center of gravity coordinates of the link, and a roll value, a pitch value, and a yaw value, which are rotation coordinates of the link at a preset origin.

Here, the inertia information may include an inertia value in a rotation direction based on each axis of x, y, and z of the link.

Here, the length information of the link may include length information of the link for each axis of x, y, and z based on the center of gravity of the link.

Here, the joint position information may include information representing the distance from the center of gravity of the link to the joint in position coordinates for each axis of x, y, and z.

The URDF file generation method according to the embodiment of the present invention is a URDF file generation method performed by the URDF file generation device, wherein α _i (an angle between z _i axis and z _{i + 1} axis), a _i (z _i and z _i Receiving a DH parameter including a vertical distance of ₊₁ ) and d _i (the distance between the x _i-1 axis and the x _i axis), and the center of gravity information, inertia information, and link length information of the link using the DH parameter And generating information including joint component information including link component information including joint position information and rotation axis information.

The method for generating a URDF file according to an embodiment of the present invention may further include receiving the number of joints before receiving the DH parameter.

Here, the step of generating the link component information and the joint component information includes generating a URDF file using pre-stored link mass information, link shape information, parent link information connected to the joint, and child link information. Can include.

Here, the center of gravity information may include information about an x value, a y value, and a z value, which are the center of gravity coordinates of the link, and a roll value, a pitch value, and a yaw value, which are rotation coordinates of the link at a preset origin.

Here, the inertia information may include an inertia value in a rotation direction based on each axis of x, y, and z of the link.

Here, the length information of the link may include length information of the link for each axis of x, y, and z based on the center of gravity of the link.

Here, the joint position information may include information representing the distance from the center of gravity of the link to the joint in position coordinates for each axis of x, y, and z.

A manipulator simulation system using a URDF file according to an embodiment of the present invention includes an interface for receiving DH (Denavit-Hartenberg) parameters, a URDF file generating device for generating a URDF file using the DH (Denavit-Hartenberg) parameters, and the URDF. It includes a simulation device that receives a file and performs a manipulator simulation.

Here, the DH (Denavit-Hartenberg) parameter information is α _i (z _i axis and the angle of the z _{i + 1} axis-to-axis), a _i (z _i and z the vertical distance of the _{i + 1)} and d _i (x _i-1 The distance between the axis and the x _i axis) may be included.

Here, the URDF generating apparatus may include a storage unit for storing the generated URDF file.

According to the apparatus and method for generating a URDF file according to an embodiment of the present invention, it is possible to quickly and easily generate a URDF file for simulation.

In addition, since it can cope with various manipulator simulation environments, it can be utilized when manufacturing a manipulator.

1 is a functional block diagram of an apparatus for generating a URDF file according to an embodiment of the present invention.
2 is an exemplary manipulator for explaining DH parameter information.
3 is information about the manipulator DH parameter of FIG. 2.
4 is an example of an algorithm for generating a URDF file according to an embodiment of the present invention.
5 and 6 are examples of input windows for generating a URDF file.
7 shows the DH parameter values of 6 links with 5 joints.
8 is an exemplary diagram of a URDF file generated by the input of FIG. 7.
9 is a flowchart of a method for generating a URDF file according to an embodiment of the present invention.
10 is a block diagram of a manipulator simulation system according to an embodiment of the present invention.

The features and effects of the present invention described above will become more apparent through the following detailed description in connection with the accompanying drawings, and accordingly, those of ordinary skill in the technical field to which the present invention pertains can easily implement the technical idea of the present invention. I will be able to.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

In describing each drawing, similar reference numerals are used for similar elements.

Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component.

For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Shouldn't.

The suffix modules, blocks, and parts for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have meanings or roles that are distinguished from each other by themselves.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement them. In the following description of the embodiments of the present invention, when it is determined that a detailed description of a related known function or a known configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a functional block diagram of an apparatus for generating a URDF file according to an embodiment of the present invention.

As shown in Fig. 1, the URDF file generation apparatus 1 according to the embodiment of the present invention is an URDF file generation apparatus for a manipulator simulation, and an input unit that receives the number of links of the manipulator and DH (Denavit-Hartenberg) parameter information. (10) and a file generation unit 20 for generating a URDF file by using the input number of links and DH parameter information. In addition, it further includes a storage unit 30 for storing the generated URDF file.

The input unit 10 receives the number of links and DH parameter information, which are basic input information for generating the URDF file. In particular, when the number of links is input, the number of sets of DH parameters to be input is also determined.

The file generation unit 20 generates a URDF file by using the number of links and DH parameter information input from the input unit 10. The URDF file is applied to various commercial simulators such as V-rep and Gazebo to create a robot model.

2 is an exemplary manipulator for explaining DH parameter information.

3 is information about the manipulator DH parameter of FIG. 2.

2 and 3, the DH parameter includes information on α _i , a _i , and d _i (where i is the number of links). Here, α _i means the angle between the z _i axis and the z _{i + 1} axis. In the Cartesian coordinate system, the z-axis (common normal) is generally based on a direction perpendicular to the plane in which the link rotates.

α _i is a parameter representing the rotation of the joint and the link, and can have values of 0, π/2, -π/2, and π with a clockwise rotation as a positive value.

a _i means the vertical distance between z _i and z _{i +1} .

As shown in FIGS. 2 and 3, a ₂ denotes a vertical distance between z ₂ and z ₃ along the x ₂ axis.

d _i means the distance between the x _i-1 axis and the x _i axis.

As shown in FIGS. 2 and 3, d ₃ denotes a spaced vertical distance between the x ₂ and x ₃ axes.

In the past, the URDF file must be newly created through the DH parameter information defined at the time of designing the manipulator.

The newly constructed URDF file had to calculate the value of a _i and d _i according to the α _i value given based on the above information, and had to input it through coding.

When the URDF file generated through the present invention is described in detail, the URDF file is divided into link component information and joint component information. The link component information includes the link's center of gravity information, inertia information, and link length information. The joint component information includes joint position information and rotation axis information.

The center of gravity information includes information on the x value, y value, z value, and the rotation coordinates of the link, such as roll value, pitch value, and yaw value, at the preset origin (generally, the link's start point or the center of the joint). Include. The link length and location relationship can be expressed through the center of gravity information.

The inertia information includes an inertia value in the rotation direction based on each axis of the link x, y, and z. In general, companies such as KUKA and Universal Robots, which manufacture robot manipulators, provide inertial information of links. This information is stored in the storage unit of the URDF file generation device according to the embodiment of the present invention, and is provided as inertia information.

Link length information includes link length information for each axis of x, y, and z based on the center of gravity of the link. In general, the length information of the link may mean how long it is in each axis of X, y, and z based on the center of the link.

The joint position information includes information representing the distance from the center of gravity of the link to the joint in position coordinates for each axis of x, y, and z. In general, the joint position information is information set how far the joint will be located in the x, y, z axis directions based on the center point of the parent link.

The rotation axis information is information indicating whether the joint axis of the robot rotates based on any of the x, y, and z axes.

In summary, the file generation unit 20 constructs a URDF file by calculating the link component information and the joint component information of the URDF file as described above through input DH parameters.

4 is an example of an algorithm for generating a URDF file according to an embodiment of the present invention.

Assuming that the number of links is N in generating a URDF file through the DH parameter using the algorithm shown in FIG. 4, when α _i is 0 or π, i+1 th a, d, center of gravity information of the link , The rotation axis information of the joint is kept the same as the previous i-th link, and if α _i is π/2, the i+1th a and d are interchanged, and the y-axis and z-axis in the joint rotation axis information are changed. , If α _i is -π/2, the i+1th a and d are interchanged, and the y-axis and z-axis in the rotation axis information of the joint are changed, and the coordinate axis expressing the length information of the link and the joint position information The y-axis and z-axis are interchanged based on the origin.

Through this algorithm, the coordinate axis of the next link is determined according to the rotation angle α of the z-axis in each link, and through this, link component information and joint component information constituting the URDF file are obtained.

The storage unit 30 stores pre-set link mass information, link shape information, and parent link and child link information of the joint.

The shape information of the link means whether the shape of the link is a rectangular shape or a cylindrical shape, and the storage unit 30 stores and sets various shape information of the link.

In addition, the mass information of the link is previously stored in the storage unit so that the value can be set according to the material of the link or the shape information of the link. The parent link and child link information sets whether the link connected to one end and the other end of the joint is a parent link or a child link.

When the parent link simulates a real robot arm, the parent link remains still and the child link moves, and the names of each parent link and child link connected to the joint can be written.

5 and 6 are examples of input windows for generating a URDF file.

As shown in FIG. 5, when the input window for operating the URDF file generating apparatus according to an embodiment of the present invention is activated, the number of joints is first input. In Fig. 5, it is an example of setting to have four joints (4 axes).

If it is set to have four joints as shown in FIG. 5, another input window as shown in FIG. 6 is activated. 6 is a window for inputting information on a link connected to each joint, and a window for inputting values of a, alpha, and d of each link from a base link to a link 4;

The URDF file generation apparatus 1 according to an embodiment of the present invention receives link information connected to each joint through the input unit 10, and when clicking convert URDF below, an algorithm as shown in FIG. 4 for generating a URDF file This works.

An example of a URDF file generated according to an input of an actually implemented DH parameter will be described with reference to FIGS. 7 and 8.

7 shows the DH parameter values of 6 links with 5 joints.

8 is an exemplary diagram of a URDF file generated by the input of FIG. 7.

When a, d, and alpha are input to each of the six link input windows having five joints as shown in FIG. 7 and the algorithm shown in FIG. 4 is applied, a URDF file as shown in FIG. 8 is generated. As described above, the URDF file generated by the URDF file generating apparatus 1 according to an embodiment of the present invention is stored in the storage unit 30 or a manipulator can be simulated by a separate simulation device.

In the above, an apparatus for generating a URDF file according to an embodiment of the present invention has been described.

Next, a method of generating a URDF file according to another aspect of the present invention will be described with reference to FIG. 9. Hereinafter, descriptions of components overlapping with the previous embodiments will be omitted for convenience of discussion.

9 is a flowchart of a method for generating a URDF file according to an embodiment of the present invention.

As shown in Fig. 9, the URDF file generation method according to the embodiment of the present invention is a URDF file generation method performed by the URDF file generation apparatus, wherein α _i (an angle between z _i axis and z _{i + 1} axis), a _i (z _i and z _{i + 1} vertical distance) and d _i (x _i-1 axis and the x _i distance between axes) of the link using the steps (S200) and the DH parameters for receiving DH parameters including the weight And generating information including link component information including center information, inertia information, and link length information, and joint component information including joint position information and rotation axis information (S300). In addition, as shown in FIG. 9, prior to the step of receiving the DH parameter, a step S100 of receiving the number of joints is further included.

The user creates a URDF file to check the simulation result of the manipulator to be designed before manufacturing the actual manipulator.

The URDF file generating device receives the number of joints of the manipulator (S100). When the number of joints is input, a window for inputting a, alpha, and d values of a link connected to the joint is activated.

DH parameters including the α _i (z _i axis and the angle of the axis-to-axis z _{i + 1),} a _i (vertical distance z _i and z _{i +1)} and d _i (x _i-1 axis and the axis-to-axis distance x _i) In the receiving step (S200), as the DH parameter value of the individual link, the manipulator for simulation receives the DH parameter of each individual link. Each input DH parameter is used as basic input data for generating a URDF file by using the algorithm of FIG. 4 described above.

Generating information including link component information including center of gravity information, inertia information, and link length information of the link, joint position information, and joint component information including rotation axis information using the DH parameter (S300) ) Includes generating a URDF file using pre-stored link mass information, link shape information, parent link information connected to the joint, and child link information. In addition to link component information and joint component information that can be calculated by the received DH parameter, mass information and shape information, which are information about individual links that can be set by the user, are received, and the names of parent and child links The etc. are newly input or entered as previously stored information.

The URDF file created through this process is used for simulation of a manipulator that is planned or is being designed.

10 is a block diagram of a manipulator simulation system according to an embodiment of the present invention.

As shown in FIG. 10, the manipulator simulation system according to an embodiment of the present invention includes an interface 2 for receiving DH (Denavit-Hartenberg) parameters, and URDF for generating a URDF file using the DH (Denavit-Hartenberg) parameters. And a file generation device 1 and a simulation device 3 that receives the URDF file and performs a manipulator simulation.

The interface 2 may mean all applicable devices capable of inputting various data such as a keyboard, mouse, and touch screen capable of inputting DH parameters by a user who designs a manipulator. In particular, the interface 2 may be various input devices capable of inputting to a GUI implemented by PyQt5, a Python GUI program, as shown in FIGS. 5 and 6.

The URDF file generation apparatus 1 may be a device including an input unit, a file generation unit for generating a URDF file, and a storage unit for storing the URDF file, as described in the previous embodiment. In particular, the URDF file generating apparatus 1 according to an embodiment of the present invention may mean all applicable devices capable of generating a URDF file through a DH parameter including link information of a manipulator.

The simulation device 3 may be a V-rep or Gazebo capable of simulating the operation and operating state of the manipulator by receiving the URDF file generated by the URDF file generating device, but is not limited thereto.

According to the software implementation, not only the procedures and functions described in the present specification, but also design and parameter optimization for each component may be implemented as a separate software module. The software code can be implemented as a software application written in an appropriate programming language. The software code may be stored in a memory and executed by a controller or a processor.

10 input
20 File creation section
30 storage

Claims (20)

As a URDF file generation device for manipulator simulation,
An input unit for receiving information on the number of links of the manipulator and DH (Denavit-Hartenberg) parameters; And
And a file generation unit for generating a URDF file using the input number of links and DH parameter information. The method of claim 1,
And a storage unit for storing the generated URDF file. The method of claim 2,
And the storage unit stores pre-set link mass information, link shape information, and parent link and child link information of the joint. The method of claim 1,
The DH (Denavit-Hartenberg) parameter information is α _i (z _i axis and z _{i + 1} of the axis-to-axis angle), a _i (vertical distance z _i and z _{i +1)} and d _i (x _i-1 and axis URDF file generating apparatus, characterized in that it includes a distance between x _i axes). The method of claim 1,
The file generation unit
Link component information including center of gravity information, inertia information, and link length information
An apparatus for generating a URDF file, characterized in that for generating information including joint component information including joint position information and rotation axis information. The method of claim 5,
Wherein the center of gravity information includes information on the x value, y value, z value, which are the center of gravity coordinates of the link, and information about a roll value, a pitch value, and a yaw value, which are rotation coordinates of the link at a preset origin. The method of claim 5,
The inertia information includes an inertia value in a rotation direction based on each axis of x, y, and z of the link. The method of claim 5,
The length information of the link includes length information of the link for each axis of x, y, and z based on the center of gravity of the link. The method of claim 5,
The joint position information includes information representing the distance from the center of gravity of the link to the joint in position coordinates for each axis of x, y, and z. As a URDF file generation method performed by a URDF file generation device,
(a) α _i comprises a (z _i axis and the angle of the axis-to-axis z _{i + 1),} a _i (vertical distance z _i and z _{i +1)} and d _i (x _i-1 axis and the axis-to-axis distance x _i) Receiving the DH parameter; And
(b) Using the DH parameter to generate information including link component information including center of gravity information, inertia information, and link length information of the link and joint component information including joint position information and rotation axis information URDF file generation method comprising the step of. The method of claim 10,
And receiving the number of joints before step (a). The method of claim 10,
Step (b)
And generating a URDF file using the previously stored link mass information, link shape information, parent link information connected to the joint, and child link information. The method of claim 10,
The center of gravity information includes information on the x value, y value, z value, which are the center of gravity coordinates of the link at a preset origin, and information about a roll value, a pitch value, and a yaw value, which are rotation coordinates of the link. The method of claim 10,
The inertia information includes an inertia value in a rotational direction based on each axis of x, y, and z of the link. The method of claim 10,
The length information of the link includes length information of the link for each axis of x, y, and z based on the center of gravity of the link. The method of claim 10,
The joint position information includes information representing the distance from the center of gravity of the link to the joint in position coordinates for each of x, y, and z axes. A recording medium on which a computer program performing the method according to any one of claims 10 to 16 is recorded. As a manipulator simulation system using URDF files,
An interface for receiving DH (Denavit-Hartenberg) parameters;
A URDF file generating device for generating a URDF file using the DH (Denavit-Hartenberg) parameter; And
A manipulator simulation system comprising a simulation device that receives the URDF file and performs a manipulator simulation. The method of claim 18,
The DH (Denavit-Hartenberg) parameter information is α _i (z _i axis and z _{i + 1} of the axis-to-axis angle), a _i (vertical distance z _i and z _{i +1)} and d _i (x _i-1 and axis x _i- axis distance). The method of claim 18,
The URDF generation device comprises a storage unit for storing the generated URDF file.

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