Project of building 3D Robotic Arm Model and its User Interface

1. Robot Arm Simulation
Author: Jiang Yucheng
Supervisor: Claude Sammut Maurice Pagnucco
Research Theme: Digital Future
Background and objectives
Robot simulation is to create embedded applications for a robot without depending physically on the
actual machine, thus saving cost and time. In some cases, these applications can be transferred on the real
robot without modifications. The objective of the project is to create a interface(driver) between
simulation robot and real robot so that the arm model will move as the physical robot is moved. And the
simulation can be applied in various scenarios to test the stretching room of Arm and whether there will
be collision to avoid breaking the robot arm in the real situation.
Hierachical structure of project
Knowledge and tools
Robot operating system(ROS)
software framework for robot software development, it provides standard operating system services.
RVIZ
A package of ROS and it functions as 3D visualization tool.
Unified Robot Description Format(URDF)
A package of ROS to represent robot model with XML format and itself contains a C++ parser
packages it will require some parameter configuration to make it
useable.
Interfacing the arm navigation node and the physical/gazebo driver
The nodes that are created generate a standardized interface which
will need to be implemented by both the physical and gazebo drivers.
In particular the information of following joint trajectory of ROS
control message must be implemented
Methods And Procedures
Create URDF of robot arm
The URDF is the main way of modeling robot arm in ROS, and it is used
in a number of ways. Firstly, it is used by Gazebo the main 3D simulator
within ROS. Secondly it is used by RVIZ. Finally, URDF is also used by
ROS tools to generate kinematic chains for planning and performing
collision detection. In general, having a good URDF model of the Robot
arm is critical first step for this project.
Generating the arm navigation packages
Once an accurate URDF model has been generated, it can be used by
the Planning Description Configuration Wizard to create the basic arm
navigation packages. Once this tool creates the basic arm navigation
IronCad 3D modeling
URDF modelling
A rough URDF was firstly created mainly with RVIZ visualization in mind. But it doesn’t include any physical
attributes such as mass and center of mass. These are important for simulation. After modification time and agian
the current URDF model is more accurate and some physical attributes have been modified or added in to satisfy
the later usage for scenario simulation. The joints in this stage can be rotated using GUI(Graphical User Interface)
but there is no collision detection neither any mass parameters taking effect.
Figure1
Figure2
Figure3
Figure4
IronCad is a 3D modeling CAD software. The first step is to create the 3D model exactly
according to the robot arm. Figure 1,2,3 show some of the joint models of arm and figure 4
shows the whole arm model with rendering effect. The model of each robot joint will be
exported separately for the usage in later stage.
Meshlab refining
Conclusion
Gazebo is a multi-robot simulator. It is capable of simulating a
population of robots, sensors and objects in a three-dimensional
world. It generates both realistic sensor feedback and physically
plausible interactions between objects .In This stage The robot arm
model can be set in specific real scenarios. The main purpose of
doing this is to detect the possible collision of joints when
performing pickup task and to simulate arm stretching to record the
stretching space of arm.
Gazebo simulation
Meshlab is an advanced 3D mesh processing
software system. It is perfect in 3D
development and data handling. In this stage
the parts are further modified to make sure
they are accurate with respect to dimensions
of the real arm. And all the parts will be
converted to Collada(.dae) files for the ease
processing of URDF in RVIZ.
The robot arm model can be simulated in certain scenarios and perform specific tasks. With respect to the interface the robot arm model will move as the real arm moves. The project has
not been completed yet and I think there are improving room in many aspects. But the experience and knowledge gained through the summer research program is invaluable.
Future Work
Discrete concrete Gazebo simulation environment should be built to satisfy the needs of everyday life scenarios or specific outdoor situation.