Sensors 2012, 12(9), 11910-11921; doi:10.3390/s120911910
Article

Slope Estimation during Normal Walking Using a Shank-Mounted Inertial Sensor

Multisensor Systems and Robotics Laboratory, University of Oviedo, Campus de Viesques, ed. 2, 33204, Gijón, Asturias, Spain
* Author to whom correspondence should be addressed.
Received: 7 June 2012; in revised form: 16 August 2012 / Accepted: 24 August 2012 / Published: 29 August 2012
(This article belongs to the Section Physical Sensors)
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Abstract: In this paper we propose an approach for the estimation of the slope of the walking surface during normal walking using a body-worn sensor composed of a biaxial accelerometer and a uniaxial gyroscope attached to the shank. It builds upon a state of the art technique that was successfully used to estimate the walking velocity from walking stride data, but did not work when used to estimate the slope of the walking surface. As claimed by the authors, the reason was that it did not take into account the actual inclination of the shank of the stance leg at the beginning of the stride (mid stance). In this paper, inspired by the biomechanical characteristics of human walking, we propose to solve this issue by using the accelerometer as a tilt sensor, assuming that at mid stance it is only measuring the gravity acceleration. Results from a set of experiments involving several users walking at different inclinations on a treadmill confirm the feasibility of our approach. A statistical analysis of slope estimations shows in first instance that the technique is capable of distinguishing the different slopes of the walking surface for every subject. It reports a global RMS error (per-unit difference between actual and estimated inclination of the walking surface for each stride identified in the experiments) of 0.05 and this can be reduced to 0.03 with subject-specific calibration and post processing procedures by means of averaging techniques.
Keywords: slope estimation; shank; inertial sensors; gait; tilt

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MDPI and ACS Style

López, A.M.; Álvarez, D.; González, R.C.; Álvarez, J.C. Slope Estimation during Normal Walking Using a Shank-Mounted Inertial Sensor. Sensors 2012, 12, 11910-11921.

AMA Style

López AM, Álvarez D, González RC, Álvarez JC. Slope Estimation during Normal Walking Using a Shank-Mounted Inertial Sensor. Sensors. 2012; 12(9):11910-11921.

Chicago/Turabian Style

López, Antonio M.; Álvarez, Diego; González, Rafael C.; Álvarez, Juan C. 2012. "Slope Estimation during Normal Walking Using a Shank-Mounted Inertial Sensor." Sensors 12, no. 9: 11910-11921.

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