EZPhysics Simulation

EZPhysics was written by RoboSavvy and was selected as the real-time simulator because it was available as source code and provides good simulation speed and networked remote control.

ezphysics.org

EZPhysics goal in this project is to provide an easy and fast way of testing control methods in a close to real simulation environment.

The development of EZPhysics application in this project refereed mainly to facilitate the insertion of the Jacobian Robot’s physical properties and the ability to work with Matlab’s Simulink environment in several configurations.
 
 
 
EZPhysics communicating with Matlab

The design and development of humanoid control is in it self a research area. Control experts usually use Matlab to easily experiment several approaches and values to achieve the desired model of control.

To allow for a better visual feedback and prototyping, a Matlab s-function was developed to communicate with EZPhysics simulation. This is done through an TCP channel using the HawkNL library to access network features both in Matlab and EZphysics.

Matlab application will Listen to port specified in the function parameters and EZPhysics application will connected to an IP and Port specified in the World Node.

1. Intergrate the s-function with the simulink model.

http://www.youtube.com/watch?v=fP5GdOikcN0

2. Setup the connection and Watch the simulation.

http://www.youtube.com/watch?v=YSKmK5Z1CC0

 
 

EZPhysics parametrization of ODE

In our project, we need to influence the robot’s movements by applying rotational force to robot’s motorized joints.

The design of ODE was made thinking on the simulation of servos (and motors in general). Due to this, beyond the possibility to apply a force to a joint, it is also possible to set the joins parameters with desired speed and maximum applicable torque to achieve that speed. This allows us to create a very simple model that represents a real servo.

To take advantage of this feature EZPhysics Editor was updated to allow for the settings of this parameters by pressing a key, which allows for the rapid prototyping of the scale of forces needed to move the hinges.

This project required a good level of detail regarding the mass and inertia values of the Jacobian robot. This data was calculated by  SolidWorks using the detailed model of the robot.

The open source project Blender was useful to convert the visual data from VRML to Ogre3D  being then imported to EZPhysics. Also EZPhysics Editor was altered to allow for manual insertion of all the physical dynamics information necessary.