Quadruped robots demonstrated extensive capabilities of traversing complex and unstructured environments. Optimization-based techniques gave a relevant impulse to the research on legged locomotion. Indeed, by designing the cost function and the constraints, we can guarantee the feasibility of a motion and impose high-level locomotion tasks, e.g., tracking of a reference velocity. This allows one to have a generic planning approach without the need to tailor a specific motion for each terrain, as in the heuristic case. In this context, Model Predictive Control (MPC) can compensate for model inaccuracies and external disturbances, thanks to the high-frequency replanning. The main objective of this dissertation is to develop a Nonlinear MPC (NMPC)-based locomotion framework for quadruped robots. The aim is to obtain an algorithm which can be extended to different robots and gaits; in addition, I sought to remove some assumptions generally done in the literature, e.g., heuristic reference generator and user-defined gait sequence. The starting point of my work is the definition of the Optimal Control Problem to generate feasible trajectories for the Center of Mass. It is descriptive enough to capture the linear and angular dynamics of the robot as a whole. A simplified model (Single Rigid Body Dynamics model) is used for the system dynamics, while a novel cost term maximizes leg mobility to improve robustness in the presence of nonflat terrain. In addition, to test the approach on the real robot, I dedicated particular effort to implementing both a heuristic reference generator and an interface for the controller, and integrating them into the controller framework developed previously by other team members. As a second contribution of my work, I extended the locomotion framework to deal with a trot gait. In particular, I generalized the reference generator to be based on optimization. Exploiting the Linear Inverted Pendulum model, this new module can deal with the underactuation of the trot when only two legs are in ...


    Access

    Download


    Export, share and cite



    Title :

    Online Optimization-based Gait Adaptation of Quadruped Robot Locomotion



    Publication date :

    2023-02-27


    Remarks:

    doi:10.15167/bratta-angelo_phd2023-02-27



    Type of media :

    Theses


    Type of material :

    Electronic Resource


    Language :

    English



    Classification :

    DDC:    629



    Locomotion gait optimization for a quadruped robot

    Oliveira, Miguel / Santos, Cristina / Ferreira, Manuel João Oliveira et al. | BASE | 2010

    Free access

    Gait optimization method for quadruped locomotion

    Maicol Laurenza / Gianluca Pepe / Antonio Carcaterra | BASE | 2022

    Free access

    Gait Adaptation in a Quadruped Robot

    Lewis, M. A. / Bekey, G. A. | British Library Online Contents | 2002


    Gait generation for real-time quadruped locomotion

    Jordaan Ernst / Fisher Callen | DOAJ | 2023

    Free access

    Quadruped robot locomotion using a global optimization stochastic algorithm

    Oliveira, Miguel / Santos, Cristina / Costa, L. et al. | BASE | 2011

    Free access