Introduction

In 1965 the Computer Graphics pioneer Ivan Sutherland envisioned the building of an ”ulti-mate display”, a multi-modal synthetic environment, which included force and touch feedback [1]. He was one of the first researchers to realize the significance of the sense of touch, especially for the enhancement of virtual worlds. As the philosopher Bertrand Russell put it in [2]:

“ it is touch that gives our sense of ”reality”... Not only our geometry and physics, but our whole conception of what exists outside us, is based upon the sense of touch.”

Nowadays, multi-modal human-machine interfaces have been established as one of the most important fundamental components of information technology of the XXI century. They already have decisive impact on all areas of our professional and private life, covering for example everyday communication, manufacturing, trade, financial services, health care, or entertainment. Technological innovations leading to high-fidelity recording and synthesis of natural signals for stimulating the human sensory system (most notably sound and image generation devices) transformed our way of life and created huge markets for professional applications and entertainment industry products