SDFusion. Release 0.0.

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1 SDFusion Release 0.0. Nov 12, 2017

3 Usage and Installation 1 Relevant Background Information and Pre-Requisits 3 2 Requirements Overview 5 i

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5 This project provides an exporter for Autodesk Fusion 360 robot models to SDFormat. This SDF file can then be used to simulate the robot model ín Gazebo, an open source robot simulator. Simulation is an important aspect in robotics, as it enables multiple people to work with one robot at the same time, as well as giving researchers the freedom to test new controls without damaging the robot. The exporter itself is a python script, which needs to be loaded into Autdesk Fusion 360 and executed. Usage and Installation 1

6 2 Usage and Installation

7 CHAPTER 1 Relevant Background Information and Pre-Requisits Use: To use this script you need a machine running Windows with Autodesk Fusion 360 installed. Furthermore your robot model needs to be in Fusion and you need to modify it as specified here. Please make yourself familiar with the concept of joints that Autodesk Fusion uses, opposed to the concept of constraining motion that most other CAD programs use. Develop: To develop this script further you need to be familiar with python, the SDFormat and the Autodesk Fusion API. Furthermore you need a basic understanding of how CAD programs work internally. Additionally you need to know about robot links, joints, kinematic chains and rotation matrices. You can find the Fusion API User s and Reference Manual here: Helpful Links: Autodesk Fusion SDFormat Gazebo 3

8 4 Chapter 1. Relevant Background Information and Pre-Requisits

9 CHAPTER 2 Requirements Overview The software requirements define the system from a blackbox/interfaces perspective. They are split into the following sections: User Interfaces - User Interfaces Technical Interfaces - technical_interfaces Runtime Interfaces and Constraints - Technical Constraints / Runtime Interface Requirements Contents: 2.1 Installation Git clone the following repository: Do NOT rename the folder/ the.py file or the.manifest file! To make the script known to Fusion, run the Script and Add-Ins command and click the green + icon beside the My Scripts folder in the dialog, as shown below. Use the dialog to browse to the location of the script.py file. The script will now be listed in the Scripts and Add-Ins dialog and you can run, edit, and debug it from there the same as any other script or add-in. You only need to do this once and Fusion will remember the script or add-in for all subsequent sessions. If the script does not show up in the Fusion script menu, restart Fusion. 2.2 Getting started Make sure that your robot model is specified correctly (see below) before running the script. Furthermore you have to adapt the script to your use case (see below). To run the script in Fusion, run the Script and Add-Ins command and select the SDFusion script. Click the Run button. The script automatically exports robot links and joints (and joint limits) to SDFormat and creates the required 5

mesh files. For large robot models the script takes several minutes to finish and Fusion will freeze during that time. When the scipt is finished a success dialog is shown in Fusion.

10 mesh files. For large robot models the script takes several minutes to finish and Fusion will freeze during that time. When the scipt is finished a success dialog is shown in Fusion. You now find your files in the desired location Model specification A good practice is to generate a dedicated simulation copy of the Fusion robot model. Therein all links of the robot have to be designed as rigid groups. All rigid groups will be exported as mesh (STL) files and will be listed in the model SDF file. Make supported that all rigid groups have a unique name! At the moment the following joint types are supported: fixed, cylindrical and ball joint. For cylindrical joints the joint limits are automatically exported. For ball joints the joint limits can t be exported, as this is not supported by the SDFormat. Make sure that all joints have a unique name! Make sure to select your robot model as the active product, otherwise your SDF file will be empty Adapting the script Two lines of the script need to be modified by the user: The variable filedir specifies the location where the generated model.sdf file will be written to. Make sure that this folder contains a folder called meshes. The variable modelname specifies the name of the robot model. This is the name under which you will find the model in Gazebo. The variable pluginfilename specifies the file name of the plugin that Gazebo should load together with this robot model. The variable pluginname specifies the name of the plugin that Gazebo should load together with this robot model. 6 Chapter 2. Requirements Overview

2.3 Context SDFusion creates SDF files and STL mesh files and stores them in the computers file system. SDFusion uses the Fusion API to retrieve information about the robot model.

11 2.3 Context SDFusion creates SDF files and STL mesh files and stores them in the computers file system. SDFusion uses the Fusion API to retrieve information about the robot model. It also sends action commands to Fusion 360 via the API. 2.4 Conventions We follow the coding guidelines: Language Python Guideline pep-0008/ Table 2.1: Coding Guidelines Tools C++ clang-format: Context 7

12 2.5 Architecture Constraints Technical Constraints / Runtime Interface Requirements Constraint Name Autodesk Fusion 360 Constraint Name Windows 8 or higher Table 2.2: Software Constraints Description Script is specific to Autodesk Fusion 360, it doesn t run under other CAD programs. Table 2.3: Operating System Constraints Description Fusion only runs on Windows or Mac, the script was developed on Windows, there it runs for sure. Table 2.4: Programming Constraints Constraint Name Description Python Easy and straight-forward developement. 2.6 User Interfaces There is no (G)UI. 2.7 Design Decisions The script shall not modify the given Fusion Robot model at all Export to STL Fusion can only export single components to STL (so not numerous components to one STL file). The aim was to only have one STL file per robot link, therefore all components of this link needed to be concluded in one single component. There are two ways to archieve this. First, generate a new component and move all subcomponents of the link to this new component. Before the script finishes all these actions need to be reversed. Second, generate a new component, and copy all subcomponents of the link to the new component. Before the script finishes the new component simply needs to be deleted. The second option was implemented. Copying all components takes a lot of time, but the script does not need to be executed very often. Deleting a new component is easier than keeping track of how many actions need to be reversed to reach the goal of not modifying the robot model. 2.8 Public Interfaces class MyoMuscle A class to hold information about all viapoints of a muscle. 8 Chapter 2. Requirements Overview

13 Public Functions init (self self, num num) Public Members number viapoints Public Static Attributes string SDFusion.MyoMuscle.number = list SDFusion.MyoMuscle.viaPoints = [] class Plugin A class to hold information about all muscles. Public Static Attributes list SDFusion.Plugin.myoMuscles = [] class ViaPoint A class to hold information about a viapoint. Public Static Attributes string SDFusion.ViaPoint.coordinates = string SDFusion.ViaPoint.link = string SDFusion.ViaPoint.number = namespace SDFusion This is an exporter for Autodesk Fusion 360 models to SDFormat. This can be loaded as an addon in Fusion 360. It exports all rigid groups of the robot model as links to STL and creates nodes in the SDF file for them. It creates SDF nodes for all joints of the robot model. Supported joint types are: fixed, revolute, and ball. Functions gazebomatrix(self self ) Global viapoint. Transforms a matrix from Fusion 360 to Gazebo. This transforms a matrix given in the Fusion 360 coordinate system to one in the Gazebo cooridnate system. Return the matrix wrt the Gazebo coordinate system 2.8. Public Interfaces 9

14 self: a matrix given wrt the Fusion 360 coordinate system vectortostring(x x, y y, z z) Converts three double values to string. This function converts three double values to a string separated by spaces. Return the string of these values x: the first double value y: the second double value z: the third double value sdfposevector(vector vector) Builds SDF pose node from vector. This function builds the SDF pose node for every joint. Return the SDF pose node vector: the vector pointing to the origin of the joint. sdfposematrix(matrix matrix) Builds SDF pose node from matrix. This function builds the SDF pose node for every link. Return the SDF pose node matrix: the transformation matrix of the link sdfinertial(physics physics) Builds SDF inertial node from physical properties. This function builds the SDF inertial node for every link. Return the SDF inertial node physics: the physical properties of a link sdfmom(tag tag, value value) Builds SDF node for one moment of inertia. This helper function builds the SDF node for one moment of inertia. Return the SDF moment of inertia node tag: the tag of the XML node value: the text of the XML node 10 Chapter 2. Requirements Overview

15 sdfinertia(physics physics) Builds SDF inertia node from physical properties. This function builds the SDF inertia node for every link. Return the SDF inertia node physics: the physical properties of a link linksdf(lin lin) Builds SDF link node. This function builds the SDF link node for every link. Return the SDF link node lin: the link to be exported jointsdf(joi joi, name_parent name_parent, name_child name_child) Builds SDF joint node. This function builds the SDF joint node for every joint type. Return the SDF joint node joi: the joint name_parent: the name of the parent link name_child: the name of the child link revolutejoint(joi joi) Builds SDF axis node for revolute joints. This function builds the SDF axis node for revolute joint. Return a list of information nodes (here one axis node) for the revolute joint joi: one revolute joint object exporttostl(occ occ, linkname linkname) Plain STL export. occ: the occurrence to be exported linkname: the name of the created STL file rigidgrouptostl(rig rig) Exports a rigid group to STL. Transforms a matrix from Fusion 360 to Gazebo Public Interfaces 11

16 This exports a rigid group as one STL file. For this all components of the rigidgroup are copied to a new component. Return a new occurrence which is used to export the relevant information to SDFormat rig: the rigid group to be exported occurrencetostl(occ occ) Exports an single occurrence to STL. This exports a single Fusion occurence as an STL file. Return a new occurrence which is used to export the relevant information to SDFormat occ: the occurrence that needs to be exported. clearname(name name) Clear filenames of unwanted characters. This function replaces all : with underscores and deletes spaces in filenames. to one in the Gazebo cooridnate system. Return the filename without : and spaces name: a filename run(context context) Exports a robot model from Fusion 360 to SDFormat. Variables design = None Global variable to make the Fusion 360 design object accessible for every function. string SDFusion.fileDir = C:/Users/annas/OneDrive/Dokumente/PaBi Global variable to make the output file directory accessible for every function. string SDFusion.modelName = Legs Global variable to make the robot model name accessible for every function. rootocc = None Global variable to make the root occurrence accessible for every function. bool SDFusion.exportViaPoints = True Global variable to specify if the exporter should export viapoints. string SDFusion.pluginFileName = libdummy.so Global variable to specify the file name of the plugin loaded by the SDF. Only necessary if exportviapoints is True. string SDFusion.pluginName = DummyPlugin Global variable to specify the name of the plugin loaded by the SDF- Only necessary if exportviapoints id True. 12 Chapter 2. Requirements Overview

17 file SDFusion.py 2.9 Solution Strategy General Strategy Using the Autodesk Fusion API you have access to nearly all information stored for a robot model. The script uses a common XML parser to generate the SDF file. For more information about SDF in general see and for additional information see below. The mesh files for links of the robot are exported by finding all rigid groups of the model. As you can only export single components to the STL mesh format, all parts of the rigid group are copied to a new component. The link information is then parsed into the SDF file. The joints of the robot are exported by finding all components of the model and finding their joints, as every joint is just associated to one component. The Fusion API provides a function that should retrieve all joints of a robot model, but it is not used here as it is implemented erroneous. After that the script finds the associated rigid groups to these joints. At this point there is also checked for non-exported links. These occur when a single part of the robot model resembles a link on its own, because then it can t be defined as a rigid group. The script finishes with a simple User Dialog in Fusion Additional Information about SDFormat and Gazebo Fusion uses a right-handed coordinate system with the y-axis point up. Gazebo uses a right-handed coordinate system with the z-axis pointing up. To handle this, the links of the robot model are rotated around the x-axis. This can be seen in the SDF file in the poses of the links. Everything else, like COM of links or associated joints, doesn t have to be rotated again! The poses in the SDF file are given as position (x-y-z) and rotation (roll-pitch-yaw). Fusion does not always use SI units, so sometimes the values of physical parameters are recalculated to be in SI units. Joints: Upper (and lower) joint limits in the SDF file (Gazebo) are the negated maximum (and minimum) joint limits retrieved from Fusion. This is due to the fact, that Gazebo rotates the child link of a joint around the parent link, and Fusion rotates the parent link around the child link Test Strategy There have been no tests developed. Testing was done manually due to the fact that neither the Fusion API nor the SDFormat specifications are very extensive. Therefore finding the right functions to use and producing the right SDF output from given information was tested using try-and-error method Libraries and external Software Contains a list of the libraries and external software used by this system Solution Strategy 13

18 Table 2.5: Libraries and external Software Name URL/Author License Autodesk Fusion overview Description Cloud-Based 3D CAD/CAM Tool About arc42 This information should stay in every repository as per their license: arc42, the Template for documentation of software and system architecture. By Dr. Gernot Starke, Dr. Peter Hruschka and contributors. Template Revision: 6.5 EN (based on asciidoc), Juni 2014 We acknowledge that this document uses material from the arc 42 architecture template, Created by Dr. Peter Hruschka & Dr. Gernot Starke. For additional contributors see html Note This version of the template contains some help and explanations. It is used for familiarization with arc42 and the understanding of the concepts. For documentation of your own system you use better the plain version Literature and references Starke-2014 Gernot Starke: Effektive Softwarearchitekturen - Ein praktischer Leitfaden. Carl Hanser Verlag, 6, Auflage Starke-Hruschka-2011 Gernot Starke und Peter Hruschka: Softwarearchitektur kompakt. Springer Akademischer Verlag, 2. Auflage Zörner-2013 Softwarearchitekturen dokumentieren und kommunizieren, Carl Hanser Verlag, Examples HTML Sanity Checker DocChess (german) Gradle (german) MaMa CRM (german) Financial Data Migration (german) Acknowledgements and collaborations arc42 originally envisioned by Dr. Peter Hruschka and Dr. Gernot Starke. Sources We maintain arc42 in asciidoc format at the moment, hosted in GitHub under the aim42-organisation. Issues We maintain a list of open topics and bugs. 14 Chapter 2. Requirements Overview

19 We are looking forward to your corrections and clarifications! Please fork the repository mentioned over this lines and send us a pull request! Collaborators We are very thankful and acknowledge the support and help provided by all active and former collaborators, uncountable (anonymous) advisors, bug finders and users of this method. Currently active Gernot Starke Stefan Zörner Markus Schärtel Ralf D. Müller Peter Hruschka Jürgen Krey Former collaborators (in alphabetical order) Anne Aloysius Matthias Bohlen Karl Eilebrecht Manfred Ferken Phillip Ghadir Carsten Klein Prof. Arne Koschel Axel Scheithauer About arc42 15

20 16 Chapter 2. Requirements Overview

21 Index D design (SDFusion attribute), 12 N number (SDFusion.MyoMuscle attribute), 9 R rootocc (SDFusion attribute), 12 S SDFusion (built-in class), 9 SDFusion.clearName() (built-in function), 12 SDFusion.exportToSTL() (built-in function), 11 SDFusion.gazeboMatrix() (built-in function), 9 SDFusion.jointSDF() (built-in function), 11 SDFusion.linkSDF() (built-in function), 11 SDFusion.MyoMuscle (built-in class), 8 SDFusion.MyoMuscle. init () (built-in function), 9 SDFusion.occurrenceToSTL() (built-in function), 12 SDFusion.Plugin (built-in class), 9 SDFusion.revoluteJoint() (built-in function), 11 SDFusion.rigidGroupToSTL() (built-in function), 11 SDFusion.run() (built-in function), 12 SDFusion.sdfInertia() (built-in function), 10 SDFusion.sdfInertial() (built-in function), 10 SDFusion.sdfMom() (built-in function), 10 SDFusion.sdfPoseMatrix() (built-in function), 10 SDFusion.sdfPoseVector() (built-in function), 10 SDFusion.vectorToString() (built-in function), 10 SDFusion.ViaPoint (built-in class), 9 V viapoints (SDFusion.MyoMuscle attribute), 9 17

Gazebo. Amirreza Kabiri Fatemeh Pahlevan Aghababa. Autumn 2017

Gazebo. Amirreza Kabiri Fatemeh Pahlevan Aghababa. Autumn 2017 Gazebo Amirreza Kabiri Fatemeh Pahlevan Aghababa Autumn 2017 History Started in fall 2002 in USC by Dr. Andrew Howard and his student Nate Koenig as a complementary simulator to Stage, Nate continue to