This work addresses the problem of stiffness estimation for robotic tasks. Online stiffness estimation can be used to improve force tracking in explicit force control schemes being also important for realistic haptic feedback in telemanipulation tasks. It also enables accurate stiffness mapping and simulation of environment dynamics. Many robotic applications involving contact with the environment can benefit from stiffness estimation. Examples can be found in the medical and industrial areas.In this book, three new online stiffness estimation algorithms are developed for robotic interaction...