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Mobile Information Systems
Volume 2015, Article ID 540512, 10 pages
Research Article

Adaptive Power Saving Method for Mobile Walking Guidance Device Using Motion Context

Department of Computer Science and Information Engineering, Inha University, Incheon 22212, Republic of Korea

Received 17 August 2015; Revised 9 November 2015; Accepted 10 November 2015

Academic Editor: Javid Taheri

Copyright © 2015 Jin-Hee Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


It is important to recognize the motion of the user and the surrounding environment with multiple sensors. We developed a guidance system based on mobile device for visually impaired person that helps the user to walk safely to the destination in the previous study. However, a mobile device having multiple sensors spends more power when the sensors are activated simultaneously and continuously. We propose a method for reducing the power consumption of a mobile device by considering the motion context of the user. We analyze and classify the user’s motion accurately by means of a decision tree and HMM (Hidden Markov Model) that exploit the data from a triaxial accelerometer sensor and a tilt sensor. We can reduce battery power consumption by controlling the number of active ultrasonic sensors and the frame rate of the camera used to acquire spatial context around the user. This helps us to extend the operating time of the device and reduce the weight of the device’s built-in battery.