Study of the Influence of Varying Diameter and Grasp-Forces on Mechanical Impedance for the Grasp of Cylindrical Objects

Independent from whether the energetical design of an actuator a kinematic or a control scheme for haptic devices is concerned, the impedance of the user and its influence on the system is always a field of question and assumptions. For a novel device assisting during catheterizations the user’s impedance is relevant to guaran-tee secure interaction in a medical context. Therefore a study with eight subjects has been made to quantify mean value and standard deviation of axial load impedance in the area of 20 Hz to 1 kHz. For this matter three grasp-force sensors have been built. Their diameters range between 5 mm and 13 mm and and they measure grasp forces between 1.5 N and 5.5 N. For analysis of all measured 192 frequency plots a LTI-based eight-element impedance model has been identified. The model’s elements were analyzed for de-pendencies on grasp-force and geometrical variations of the grasp-cylinder. As a result the median impedance range and its statistical spread have been quantified and a trend for the dependencies of named factors was formulated