Linear Time-invariant Systems

control scheme, in which different time scales for the rigid body subsystem dynamics and for the flexible dynamics are used (Canudas de Wit et al., 1996). An application of the two-time scale method is shown, for example, in Kang, Yeung, and Mills (2002). In summary, the aim of the authors to provide an upperlevel undergraduate and graduate textbook and a reference for experienced professionals in the fields of flexible robot dynamics and controls has been achieved. The book offered me some quite interesting reading. Even if I hope to be quite familiar with the field of robot controls, it is interesting and might be useful to become aware of the wealth of knowledge accumulated during several years of research and development in flexible robots and structures at Sandia National Laboratories. The manner of presentation seems to be comprehensive and a valuable addition to the literature for practitioners and researchers working in control of elastic structures. However, in view of the general title, it would have been useful to include some other aspects of flexible robot controls, and its usefulness will be further enhanced if it is supplemented with literature addressing other results and advanced approaches concerning the analysis and controller synthesis of this complicated system.