step length estimation using handheld inertial sensors步长估计使用手持惯性传感器.pdf

Sensors 2012, 12, 8507-8525; doi:10.3390/s120708507 OPEN ACCESS sensors ISSN 1424-8220 /journal/sensors Article Step Length Estimation Using Handheld Inertial Sensors Valérie Renaudin*, Melania Susi and Gérard Lachapelle PLAN Group, Schulich School of Engineering, The University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada; E-Mails: msusi@ucalgary.ca (M.S.); gerard.lachapelle@ucalgary.ca (G.L.) * Author to whom correspondence should be addressed; E-Mail: valerie.renaudin@ifsttar.fr; Tel.: +1-403-210-9802; Fax: +1-403-284-1980. Received: 2 May 2012; in revised form: 12 June 2012 / Accepted: 13 June 2012 / Published: 25 June 2012 Abstract: In this paper a novel step length model using a handheld Micro Electrical Mechanical System (MEMS) is presented. It combines the user’s step frequency and height with a set of three parameters for estimating step length. The model has been developed and trained using 12 different subjects: six men and six women. For reliable estimation of the step frequency with a handheld device, the frequency content of the handheld sensor’s signal is extracted by applying the Short Time Fourier Transform (STFT) independently from the step detection process. The relationship between step and hand frequencies is analyzed for different hand’s motions and sensor carrying modes. For this purpose, the frequency content of synchronized signals collected with two sensors placed in the hand and on the foot of a pede