Walking mechanisms: study and design for use in sandy environments - Gregorio Romero Rey; María Luisa Martínez Muneta; Antonio Carretero Díaz; Juan de Dios Sanz Bobi; Jorge González Onieva (Advances In Design Engineering: Proceedings Of The Xxix International Congress Ingegraf. 20-21 June 2019, Logroño, Spain, 2020)