Conditioning vs. excitation time for estimating impedance parameters of the human arm

The human arm´s capability to alter its impedance has motivated multiple developments of robotic manipulators and control methods. It provides advantages during manipulation such as robustness against external disturbances and task adaptability. However, how the impedance of the arm is set depends on the manipulation situation; a general procedure is lacking. This paper aims to fill this gap by providing a method to estimate the impedance parameters of the human arm, while taking the numerical stability of the approach into account. A dynamic arm model and an identification method is presented. Confidential criteria to determine the accuracy of the estimated parameters are given. Finally, the procedure is validated in an experiment with a human subject and the results are discussed.