Notes

Important Note: Due to problems with the 2.4 branch of Blender, the software is currently restructured and ported to the newer Blender branches 2.5 and 2.6. This should resolve existing issues, result in a cleaner and better interface, and make the creation of models a lot easier (also thanks to the many improvements made by the Blender developers). The new version is expected to be finished at the end of December 2011 or in early 2012.

Contact: stefan.ulbrich at kit.edu

Robot Editor

The Robot Editor is a modelling tool that allows easily to create new or convert existing models of robot hands. It is based on available and reliable open source software:

• COLLADA in version 1.5 has been chosen as the common content exchange format.
• It has been designed as as plugin for Blender, implemented as a set of Python scripts. It is easily extendable and supports a variety of file formats including Collada 1.4 the predecessor of the exchange format, that could be used as a starting point for further development.

Features

• Geometric modeling: The modelling of new robots requires a tool that excels in modeling of the geometrical components (i.e. meshes).
• Semantic modeling: Even more important is the ability to allow the description of semantic properties of the robot manipulator, such as the definition of kinematic chains, sensors, actuators, etc –or even specify algorithms.
• Dynamics modeling: Another important aspect is the ability to define physical attributes of the robot’s elements. At the moment, the focus lies on the dynamics of rigid bodies.
• Conversion: Robot models usually come in a variety of different file formats. The modelling tool needs to be capable to process these formats and convert them into the COLLADA standard. Especially GraspIt! files –being an already widely used standard with many conform models available– should be usable by the simulator.

COLLADA File Format for Robot Models

For the storage of models of robot manipulators and hands, we were looking for an open, extensible and already widely accepted file format that supports the definition of at least kinematics and dynamics. This is necessary in order to enable the exchange of robot models between supporting applications, leading to greater flexibility in the selection of appropriate tools.

Since version 1.5, the standard contains many useful constructs dedicated to describing kinematic chains and dynamics that can be used directly for the description of robot models. COLLADA is an XML-based file format that enables and encourages developers to extend the specification to their needs without having to violate the underlying schema definition.

In order to support specific robot features like sensors and actuators, this mechanism has been used to extend COLLADA partially using the original OpenRAVE file definition. These additions are specific to the simulator and are hidden to all other applications so that compatibility remains guaranteed. So far, basic support for COLLADA import and export has been included in the simulator.

The specification of the COLLADA format to create robot Models in Openrave can be found here.

Software requirements

• Blender: It has been developed under version 2.49a and it is hence recommended to use also this version (Download it here).

Download

The latest running version of the RobotEditor should be only accessed through subversion, see here.

Getting started

1. Getting used to Blender

   Blender has a very consistent and productive user interface. However, as it is non-standard, it is strongly recommended to first read the official tutorials for using the Blender UI, about Blender windows and navigation in 3D space.

2. Configure Blender to find the RobotEditor plugin

   Change the folder in which Blender expects scripts to reside. This location can be entered by enlarging the user preferences window (dragging the window border) and selecting File Paths. The path has to point to the your RobotEditor/ directory. For example see the following image:

   

   Once you changed the path you should be able to select the Robot Editor from a scripts window with Scripts > Wizards > Grasp Robot Editor, after having updated the menus: Scripts > Update Menus.

   

Tutorials

• Create a Collada 1.5 model