Virtual technical trainer: learning how to use milling machines with multi-sensory feedback in virtual reality

This paper describes the use and characteristics of a virtual reality system called the virtual technical trainer (VTT). This system is dedicated to vocational training courses on using and programming numerically-controlled milling machines. It aims at replacing the conventional mechanical milling machines which are currently used in such vocational training courses. VTT proposes an interactive manipulation of a cutter of a virtual milling machine, with visual, audio and haptic (force) feedback. VTT uses a haptic device which was specifically designed for the purpose of our pedagogical application. When the virtual cutter mills a piece of material, a plastic deformation algorithm is used and the material is progressively carved. Trainees can feel the cutting effort thanks to a force feedback which varies as a function of different simulation parameters (rotation speed of the tool, type of material to carve, etc). Realistic audio feedback (which was recorded in real situations) and additional visual assistance may be added, in order to increase the perception and understanding of the milling task. A preliminary evaluation of VTT showed that this simulator could be used by vocational trainers successfully. It could help them to teach the basic principles of machining at the first stages of vocational training courses on numerically-controlled milling machines.