New generation of wearable goniometers for motion capture systems

Abstract

BackgroundMonitoring joint angles through wearable systems enables human posture and gesture to be reconstructed as a support for physical rehabilitation both in clinics and at the patient’s home. A new generation of wearable goniometers based on knitted piezoresistive fabric (KPF) technology is presented.MethodsKPF single-and double-layer devices were designed and characterized under stretching and bending to work as strain sensors and goniometers. The theoretical working principle and the derived electromechanical model, previously proved for carbon elastomer sensors, were generalized to KPF. The devices were used to correlate angles and piezoresistive fabric behaviour, to highlight the differences in terms of performance between the single layer and the double layer sensors. A fast calibration procedure is also proposed.ResultsThe proposed device was tested both in static and dynamic conditions in comparison with standard electrogoniometers and inertial measurement units respectively. KPF goniometer capabilities in angle detection were experimentally proved and a discussion of the device measurement errors of is provided. The paper concludes with an analysis of sensor accuracy and hysteresis reduction in particular configurations.ConclusionsDouble layer KPF goniometers showed a promising performance in terms of angle measurements both in quasi-static and dynamic working mode for velocities typical of human movement. A further approach consisting of a combination of multiple sensors to increase accuracy via sensor fusion technique has been presented.

Human Joint Angle Estimation with Multiple-strip E-textile Stretching Sensor

“…(6,7) Their electronic goniometer with a double-layered configuration shows promising performance even for stretching properties. However, when a stretch sensor is applied to the human body, the elongation capability of the sensor against the actual stretching of the skin is an important and critical factor.…”

Assessment of a Smart Sensing Shoe for Gait Phase Detection in Level Walking

“…The results obtained have shown the possibility to use personal wearable devices to assist and support chronic patients [1][2][3][4][5][6][7], elderly people [8,9], emergency operators [10,11] and also healthy subjects for sports, wellness and prevention [12][13][14]. At the same time, the wearable technology market has exploded and is expected to further increase over the next few years, as proved by the growing interest of big players such as Google, Apple and Samsung.…”

Dynamic Gesture Recognition Using a Smart Glove in Hand-Assisted Laparoscopic Surgery

“…The sensor output is the electrical resistance difference (∆R) of the two sensing layers. We demonstrated earlier that the sensor output is proportional to the flexion angle (θ) [14], which is the angle delimited by the tangent planes to the sensor extremities (Figure 3b).…”

“…Figure 2a shows the position of the goniometers on the glove, while Figure 2b show the final prototype of the glove where the goniometers are insulated with an additional layer of black fabric. The textile goniometers are double layer angular sensors, as previously described in [14,15]. The sensing layers are knitted piezoresistive fabrics (KPF) that are made of 75% electro-conductive yarn and 25% Lycra [16,17].…”