“…In summary, it can be seen that the papers gathered in the Special Issue contributed either by proposing solutions to the general problem of state, input and/or parameter estimation [ 4 , 5 , 7 , 8 , 9 ], and/or by suggesting applications of the combined use of sensors and multibody models to different fields, such as automotive [ 6 , 8 , 9 ], railway [ 2 ], naval [ 5 ], spatial [ 10 ], machinery [ 4 , 7 ], robotics [ 3 ], biomechanics [ 1 ] and music [ 6 ] applications, thus showing the theoretical challenges and practical interest of this research topic.…”