Wednesday, April 30, 2014

GCC: Linux gnu/XXX.h: No such file or directory

It can happen a lot when you receive a compiler error alerting for instance: "gnu/stubs-32.h: No such file"
The best you can do is just:
$ yum whatprovides *stubs-32.h
# yum install $RESULT

Monday, April 28, 2014

An EKF for Real-Time Estimation and Control of a RLFJ Manipulator

An Extended Kalman Filter for Real-Time Estimation and Control of a Rigid-Link Flexible-Joint Manipulator
The project of Random Signals, Adaptive, and Kalman Filtering course, under supervision of Dr. Parsa.
Abstract—High performance tracking of an industrial robot depends on accurate expression of manipulator dynamics. When a robot has flexible joints efficient model parametrization will be difficult to achieve. In this course project report an extended Kalman filter (EKF) observer to estimate manipulator states is presented. In a computer simulation the estimation performance is demonstrated. Experimental setup for KUKA/DLR Light-Weight robot in Human Robot Interaction at the University of Western Ontario is also carried out without any success.
Documents and MATLAB and Maple files can be downloaded here.

Wednesday, April 23, 2014

Skew symmetry property

The three types of derivatives: vectors-by-matrices, matrices-by-vectors, and matrices-by-matrices. These are not as widely considered and a notation is not widely agreed upon. However the second type (matrices-by-vectors) is widely used in Robotics.
If we consider the following state form for a robot:
 M(\theta )\ddot \theta  + C(\theta ,\dot \theta )\dot \theta  + g(\theta ) = \tau    

The matrix N(\theta ,\dot \theta ) = \dot M(\theta ) - 2C(\theta ,\dot \theta ) is skew-symmetric.
Here the matrix-by-vector derivative is:                                                              

{\dot m_{kj}} = \sum\limits_i^n {\frac{{\partial {m_{kj}}}}{{\partial {\theta _i}}}} {\dot \theta _i}                   

Note that this is not true if the robot dynamics is expressed in any other forms (for exampleM(\theta )\ddot \theta  + R(\theta ,\dot \theta ) + g(\theta ) = \tau ).

Tuesday, April 8, 2014


If you need a spacer for connecting FESTO adaptive gripper DHDG to the end-effector of KUKA/DLR Lightweight Robot here is the link to download the SolidWorks design CAD file.