This can be used to profile users jogging [18]. This senses one specific type of user mobility, i.e., walking (or jogging or running), via the foot pressure surges, as someone repeatedly steps on the ground. As only one sensor is used for the whole of one foot, the system does not monitor the full value of ground reaction force generated from one foot. This limits the system from detecting fine-grained human postures, e.g., differentiating between standing and sitting. In addition, by only sensing the movement in one foot rather than in both feet, it cannot differentiate other mobility activities that involve both feet, e.g., cycling and driving a car. These limitations may also introduce more errors in differentiating between a body rocking and swaying versus stepping.

Single wearable sensor based methods, whilst to some extent achieving some useful mobility recognition results, tend to suffer some common limitations such as low accuracy, narrow range and a coarse mobility recognition capability [16,19,20]. In contrast, multi-sensor based methods that combine two or more sensors normally outperform the single-sensor based methods in terms of a higher accuracy but they also require more resources, e.g., have a higher computation, higher cost, and can be harder to maintain [21,22]. Despite the added deployment challenges, multi-sensor based methods and hybrid sensor methods that combine wearable sensors and mobile or accompanied device sensors, have received increasing attention [18,23].

In contrast to a single wearable sensor used as a pedometer, multi-sensor types of wearable foot force sensor system can be used to capture richer and more finely grained user foot force variations caused by GSK-3 different human postures, e.g., standing and sitting and activities, e.g., cycling and driving in real time [14]. However, the use of the foot force sensors to support richer mobility activities recognition also faces significant challenges. Different mobility activities may exhibit similar foot force patterns, which can be hard to differentiate, e.g., car passengers and seated bus passengers sometimes generate quite similar foot force patterns. This can be addressed through the joint inference with other sensor types, e.g., GPS. The variability in where sensors are placed can produce different sensor measurements. This can be addressed, when it is feasible, by fixing the sensor position, e.

g., using a standard shoe inset. For the same type of user activity, user mo
The growth of small devices with constrained capabilities and Internet Protocol (IP)-based networking connectivity is today a reality. They typically form self-configurable wireless multi-hop networks of relay nodes, which are able to recover from communication failures. Due to these features, they have become an important part of the Smart Grid, as well as sensor networks, such as the Internet of Things.