Stair fall risk detection using wearable sensors

Stair falls continue to be a prominent cause of unintentional injury in older people. They can result in significant losses of mobility and independence, which greatly affects their quality of life, and in some cases can be fatal. Research has demonstrated that 'foot clearance' and its variability are sensitive fall risk parameters during stair negotiation. Foot clearance is defined as the distance between the foot and stair edge during the swing phase. Foot clearance is different from other gait parameters; there is an explicit mechanism that links reduced foot clearance to falls. Therefore, it is necessary to understand fall predictors and develop a system to reduce the frequency of tripping related falls. However, there is no direct method to calculate foot clearance. Recently there has been an increased interest in the development of portable sensor devices for measuring critical parameters of human movement. This study investigates a new method for measuring foot clearance during stair ascent and descent in six healthy adults. A shoe has been instrumented with sensors to calculate foot clearance and foot angle using a VL6180X distance sensor and a BNO055 IMU sensor. A Lab VIEW program has been created to collect the sensor data using a TI CC2540 low energy Bluetooth. One of the participants had less foot clearances compared to other participants regardless of ascending and descending. This reduced foot clearance probably suggests higher risk of tripping and slipping the steps during stair negotiation.