{'fraction_non_alphanumeric': 0.015511892450879007, 'fraction_numerical': 0.0, 'mean_word_length': 5.165605095541402, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Reduced-order observer for mechanical systems with elastic joints

The paper considers an example of mechanical system with high relative degree: a fully actuated robot with elastic joints and the related control problem. The considered system is characterized by a uniform relative degree five, assuming as available output only the joints' angles. Two different strategies can be exploited to address this control problem. A first possibility is to use a full order observer and to exploit the observer's state instead of the actual system's state to design the feedback control law. A second methodology consists in introducing differentiators to reduce the system's relative degree. In the paper the presented strategy is a compromise between the two approaches. The adopted criterion to stop the differentiation procedure is given by the existence of a global solution of a reduced order matrix inequality and by designer's capability to compute such a solution.