title: Extraction of user's navigation commands from upper body force interaction in walker assisted gait.
abstract: BACKGROUND
  The advances in technology make possible the incorporation of sensors and actuators in rollators, building safer robots and extending the use of walkers to a more diverse population. This paper presents a new method for the extraction of navigation related components from upper-body force interaction data in walker assisted gait. A filtering architecture is designed to cancel: (i) the high-frequency noise caused by vibrations on the walker's structure due to irregularities on the terrain or walker's wheels and (ii) the cadence related force components caused by user's trunk oscillations during gait. As a result, a third component related to user's navigation commands is distinguished.
  
  
  RESULTS
  For the cancelation of high-frequency noise, a Benedict-Bordner g-h filter was designed presenting very low values for Kinematic Tracking Error ((2.035 +/- 0.358).10(-2) kgf) and delay ((1.897 +/- 0.3697).10(1)ms). A Fourier Linear Combiner filtering architecture was implemented for the adaptive attenuation of about 80% of the cadence related components' energy from force data. This was done without compromising the information contained in the frequencies close to such notch filters.
  
  
  CONCLUSIONS
  The presented methodology offers an effective cancelation of the undesired components from force data, allowing the system to extract in real-time voluntary user's navigation commands. Based on this real-time identification of voluntary user's commands, a classical approach to the control architecture of the robotic walker is being developed, in order to obtain stable and safe user assisted locomotion.
authors.affiliation: Bioengineering Group, Consejo Superior de Investigaciones Cientificasi, Crta, Campo Real Km 0,200, Arganda del Rey - Madrid, Spain. frizera@iai.csic.es
authors.forename: Anselmo
authors.initials: A
authors.lastname: Frizera Neto
authors.forename: Juan A
authors.initials: JA
authors.lastname: Gallego
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rocon
authors.forename: José L
authors.initials: JL
authors.lastname: Pons
authors.forename: Ramón
authors.initials: R
authors.lastname: Ceres
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D005684:Gait; D015203:Reproducibility of Results; D012371:Robotics / Q000379:methods*; D014584:User-Computer Interface; D014853:Walkers