Walking speed estimation is an essential component of mobile apps in various fields such as fitness, transportation, navigation, and health-care. Most existing solutions are focused on specialized medical applications that utilize body-worn motion sensors. These approaches do not serve effectively the general use case of numerous apps where the user holding a smartphone tries to find his or her walking speed solely based on smartphone sensors. However, existing smartphone-based approaches fail to provide acceptable precision for walking speed estimation. This leads to a question: is it possible to achieve comparable speed estimation accuracy using a smartphone over wearable sensor based obtrusive solutions? We find the answer from advanced neural networks. In this paper, we present DeepWalking, the first deep learning- based walking speed estimation scheme for smartphone. A deep convolutional neural network (DCNN) is applied to automatically identify and extract the most effective features from the accelerometer and gyroscope data of smartphone and to train the network model for accurate speed estimation. Experiments are performed with 10 participants using a treadmill. The average root- mean-squared-error (RMSE) of estimated walking speed is 0.16m&#x002F;s which is comparable to the results obtained by state-of- the-art approaches based on a number of body- worn sensors (i.e., RMSE of 0.11m&#x002F;s). The results indicate that a smartphone can be a strong tool for walking speed estimation if the sensor data are effectively calibrated and supported by advanced deep learning techniques.
Abstract Here, we present IDNet, a user authentication framework from smartphone-acquired motion signals. Its goal is to recognize a target user from their way of walking, using the accelerometer and gyroscope (inertial) signals provided by a commercial smartphone worn in the front pocket of the user’s trousers. IDNet features several innovations including: (i) a robust and smartphone-orientation-independent walking cycle extraction block, (ii) a novel feature extractor based on convolutional neural networks, (iii) a one-class support vector machine to classify walking cycles, and the coherent integration of these into (iv) a multi-stage authentication technique. IDNet is the first system that exploits a deep learning approach as universal feature extractors for gait recognition, and that combines classification results from subsequent walking cycles into a multi-stage decision making framework. Experimental results show the superiority of our approach against state-of-the-art techniques, leading to misclassification rates (either false negatives or positives) smaller than 0.15 with fewer than five walking cycles. Design choices are discussed and motivated throughout, assessing their impact on the user authentication performance. Objective : Accurate estimation of spatial gait characteristics is critical to assess motor impairments resulting from neurological or musculoskelet al disease. Currently, however, methodological constraints limit clinical applicability of state-of-the-art double integration approaches to gait patterns with a clear zero-velocity phase. Methods : We describe a novel approach to stride length estimation that uses deep convolutional neural networks to map stride-specific inertial sensor data to the resulting stride length. The model is trained on a publicly available and clinically relevant benchmark dataset consisting of 1220 strides from 101 geriatric patients. Evaluation is done in a tenfold cross validation and for three different stride definitions. Results : Even though best results are achieved with strides defined from midstance to midstance with average accuracy and precision of @math , performance does not strongly depend on stride definition. The achieved precision outperforms state-of-the-art methods evaluated on the same benchmark dataset by @math . Conclusion : Due to the independence of stride definition, the proposed method is not subject to the methodological constrains that limit applicability of state-of-the-art double integration methods. Furthermore, it was possible to improve precision on the benchmark dataset. Significance : With more precise mobile stride length estimation, new insights to the progression of neurological disease or early indications might be gained. Due to the independence of stride definition, previously uncharted diseases in terms of mobile gait analysis can now be investigated by retraining and applying the proposed method. Walking impairment resulted by various chronic diseases, disorders and injuries have been investigated using recent emerging wearable technology, for instance, gait assessment using inertial body sensors in 6-minute walk (6MW) for persons with Multiple Sclerosis (PwMS) to identify spatiotemporal features useful to assess MS progression. However, most studies to date have investigated the features extracted from movements of the lower limbs and do not provide a holistic gait assessment. A recent pilot study demonstrated that the holistic gait assessment such as evaluating the associations among lower and upper limbs provided better discrimination between healthy controls and PwMS. This paper is motivated by this and further aim to answer the following question: can we identify the temporal gait patterns in terms of the holistic gait assessment? Traditionally this suffers from the statistical property of the causality inference method adopted by previous study. We proposed a deep convolutional neural network (CNN) to learn the temporal and spectral associations among the time-series motion data captured by the inertial body sensors. A simulated model was developed to train the CNN, and then the trained CNN was adopted to assess the gait performance from a pilot dataset with 41 subjects (28 PwMS and 13 healthy controls). Experimental results are reported to illustrate the performance of the proposed approach.