Test-Bench for the Characterization of Flexion Sensors Used in Biomechanics

The design, prototyping and validation of an innovative test bench for the characterization and the hysteresis measurement of flexion sensors are presented in this paper. The device, especially designed to test sensors employed in the biomedical field, can be effectively used to characterize also sensors intended for other applications, such as wearable devices. Flexion sensors are widely adopted in devices for biomedical purposes and in this context are commonly used in two main ways: to measure movements (i) with fixed radius of curvature and (ii) with variable radius of curvature. The test bench has been conceived and designed with reference to both of these needs of use. The technological choices have been oriented towards simplicity of manufacture and assembly, configuration flexibility and low cost of realization. For this purpose, 3D printing technology was chosen for most of the structural components of the device. To verify the test bench performances, a test campaign was carried out on five commercial bending sensors. To characterize each sensor, the acquired measurements were analysed by assessing repeatability and linearity of the sensors and hysteresis of the system sensor/test bench. A statistical analysis was performed to study the positioning repeatability and the hysteresis of the device. The results demonstrate good repeatability and low hysteresis.