Ambulatory Assessment of Balance

Gait analysis is commonly done in gait laboratories, where several gait variables are estimated using measurement systems installed in the laboratory. Two important variables to characterize human gait are the center of mass and the center of pressure. The major drawback of existing measurement systems is their restriction to the laboratory. This study demonstrates the possibilities of an ambulatory measurement system: the forceshoe. It consists of an orthopaedic sandal with six-degrees-of-freedom force/moment sensors beneath the heel and the forefoot and an inertial sensor rigidly attached to each force/moment sensor. For validation, the measurement system has been compared to a reference system consisting of an optical position measurement system and two force plates. The root-mean-square (rms) difference between the center of pressure trajectories was (5.1±0.7) mm, corresponding to (1.7±0.3)% of the length of the shoe. The rms differences between the center of mass trajectories estimated by both measurement systems was (0.025 ± 0.007) m. Based on the results presented in this study, it is concluded that the instrumented shoe allows accurate and continuous estimation of gait variables that can be used to assess balance.