Advanced Robotics, Vol. 21, No. 3–4, pp. 267–291 (2007)  VSP and Robotics Society of Japan 2007. Also available online - www.brill.nl/ar Full paper Reactive robot system using a haptic interface: an active interaction to transfer skills from the robot to unskilled persons JORGE SOLIS ∗ , SIMONE MARCHESCHI, ANTONIO FRISOLI, CARLO ALBERTO AVIZZANO and MASSIMO BERGAMASCO Scuola Superiore Sant’Anna, Perceptual Robotics Laboratory, Viale Rinaldo Piaggio, 34, 56127 Pontedera (PI), Italy Received 13 December 2005; accepted 20 March 2006 Abstract—This paper is concerned with the reactive robot system (RRS) which has been introduced as a novel way of approaching human–robot interactions by exploiting the capabilities of haptic interfaces to transfer skills (from the robot to unskilled persons). The RRS was implemented based on two levels of interaction. The first level, which implements the first two stages of the learning process, represents the conventional control way of interchanging a set of forces in response to a static read of the contact position of some pre-defined dynamic rules (passive interaction). The second level, which implements the last stage of the learning process, represents an enhanced way of interaction between haptic interfaces and humans. This level adds to robotic system a degree of intelligence which enables the robot to dynamically adapt its behavior depending on user wishes (active interaction). In particular, in this paper, the implementation of the second level of the RRS is described in detail. A set of experiments was performed, applied to Japanese handwriting, to verify if second level of the RRS can interact with humans during the autonomous stage of the learning process. The results demonstrated that our system can still provide assistance to users on the autonomous stage while mostly respecting their intentions without significantly affecting their performance. Keywords: Haptic interfaces; human–robot interaction; human learning process; hidden Markov models; handwriting. 1. INTRODUCTION Human–robot interaction (HRI) can be defined as the study of humans, robots and the ways they influence each other. As a discipline, HRI regards the analysis, design, implementation and evaluation of robots for human use. One of the most challenging problems in the HRI research field is giving the robot an understanding ∗ To whom correspondence should be addressed. E-mail: solis@sssup.it