4 Human–Robot Cognitive Interaction L. Bueno, F. Brunetti, A. Frizera, J.L. Pons Bioengineering Group, Instituto de Autom´ atica Industrial, Consejo Superior de Investigaciones Cient´ ıficas 4.1 Introduction to Human–Robot Interaction The symbiotic relationship between humans and robots transcends the boundaries of simple physical interaction. It involves smart sensors, actuators, algorithms and control strategies capable of gathering and decoding complex human expressions or physiological phenomena. Once this process is complete, robots use the information to adapt, learn and optimize their functions, or even to transmit back a response resulting from a cognitive process occurring within the robot. A cognitive process is a sequence of tasks including reasoning, planning, and finally the execution of a previously identified problem or goal. Originally this concept was restricted to living creatures, but now it can also be applied to smart robots which accomplish the above- mentioned sequence of tasks. The Human-Robot Cognitive Interface is the link between human and robot, in which the information regarding these processes is acquired and trans- mitted bidirectionally. New human-machine interfaces have recently been developed to support all the flow of information that a smart system needs in order to perform its function. Scientists consider this cognitive interaction fundamental. Thus we can find terms like Human-Machine Interface Wearable Robots: Biomechatronic Exoskeletons. Edited by J. L. Pons c 2001 John Wiley & Sons, Ltd