[IEEE 2006 IEEE Conference on Computer Aided Control System Design, 2006 IEEE International Conference on Control Applications, 2006 IEEE International Symposium on Intelligent Control - Munich, Germany (2006.10.4-2006.10.6)] 2006 IEEE Conference on Computer Aided Control System Design, 2006 IEEE International Conference on Control Applications, 2006 IEEE International Symposium on Intelligent Control - Disturbance estimation by generalized internal model control and its application to assistive devices for rehabilitation technology