Search results for "Flexible Robot"
showing 4 items of 4 documents
An Input Observer-Based Stiffness Estimation Approach for Flexible Robot Joints
2020
This letter addresses the stiffness estimation problem for flexible robot joints, driven by variable stiffness actuators in antagonistic setups. Due to the difficulties of achieving consistent production of these actuators and the time-varying nature of their internal flexible elements, which are subject to plastic deformation over time, it is currently a challenge to precisely determine the total flexibility torque applied to a robot's joint and the corresponding joint stiffness. Herein, by considering the flexibility torque acting on each motor as an unknown signal and building upon Unknown Input Observer theory, a solution for electrically-driven actuators is proposed, which consists of …
Force/Torque-Sensorless Joint Stiffness Estimation in Articulated Soft Robots
2022
Currently, the access to the knowledge of stiffness values is typically constrained to a-priori identified models or datasheet information, which either do not usually take into ac- count the full range of possible stiffness values or need extensive experiments. This work tackles the challenge of stiffness estimation in articulated soft manipulators, and it proposes an innovative solution adding value to the previous research by removing the necessity for force/torque sensors and generalizing to multi-degree- of-freedom robots. Built upon the theory of unknown input-state observers and recursive least-square algorithms, the solution is independent of the actuator model parameters and its in…
Robust and Decoupled Position and Stiffness Control for Electrically-Driven Articulated Soft Robots
2022
The control of articulated soft robots, i.e. robots with flexible joints and rigid links, presents a challenge due to their in- trinsic elastic elements and nonlinear force-deflection dependency. This letter first proposes a discrete-time delayed unknown input- state observer based on a nominal robot model that reconstructs the total torque disturbance vector, resulting from the imperfect knowledge of the elastic torque characteristic, external torques, and other model uncertainties. Then, it introduces a robust controller, that actively compensates for the estimated uncertainty and allows bounded stability for the tracking of independent link position and joint stiffness reference signals.…
Robust Control of Nonlinear Systems: An Unknown Input Observer Based Approach
2023
Questa tesi propone un controllore robusto per sistemi non lineari tramite l'utilizzo di un osservatore ad ingressi sconosciuti. Attraverso un'opportuna riformulazione dinamica del modello, un generico sistema non lineare viene descritto come la somma di due funzioni, la prima lineare e nota e la seconda altamente non lineare e sconosciuta, derivante dalla conoscenza imperfetta del modello dinamico, dei parametri, o di eventuali disturbi esogeni agenti sul sistema etc., modellabili come perturbazioni (disturbi) della funzione lineare. Questa semplificazione consente una vantaggiosa descrizione dinamica del sistema in forma matriciale. Le informazioni necessarie sono stimate attraverso l'uti…