Modeling Mechanical Impedance of Environment in Flexible Robotics Applications

Control of flexible robots that interact with the environment presents some difficulties mainly due to the fact that mechanical impedance of such environment is unknown. This paper deals with modeling the mechanical impedance of the environment when an one-link flexible arm contacts it. Elastic and viscoelastic models, the latter of both integer and fractional orders, are considered in this work to classify the contacted environment. Experimental results, corresponding to impacts with 26 different soft objects, are given to identify the parameters of the above-mentioned models. The goodness of the adjustment of each model is analyzed by a set of performance indices. Results show that, in most cases, the best characterization is provided by the viscoelastic model of fractional order.