Technological advancements in the analysis of human motion and posture management through digital devices

Table 1 Studies investigating the reliability of inertial measurement unit sensors

Ref.	Sensor/position	Comparison system	Results	Outcomes
Qiu et al[29], 2016	3 magnetic angular rate and gravity/thigh, shank, and foot	Vicon	Position accuracy of 0.3%, the ΔXY radial distance error of 0.82% and the distance error of 0.27%, position error of 0.4%	The combination of distributed wearable sensors with the Denavit–Hartenberg convention resulted in a promising tool for tracking lower limb movements
Sprager et al[30], 2015	1 multi-sensor platform integrated into a smart garment/knee	NP	Good activity discrimination can be achieved based RMSE and SD from flexible sensor, acceleration and gyroscope data	Preliminary results show that walking, running, stairs climbing can be discriminated based on the data collected
Cresswell et al[33], 2017	4 Shimmer3 sensor nodes/all sides of the shank	NP	The results of the fixed effects models highlighted the discrepancies between front–back mounting versus inner–outer mounting	For y-axis gyroscope data, the variation is mostly influenced by mounting location. Mounting location should not vary but if it has to vary, it is better for it to vary between inner and outer leg mounting locations
Fusca et al[35], 2018	1 IMU/posterior CoM	Elite (BTS)	Mean absolute percentage error of: Stride time is 5.7%; Cadence is 4.9%; Step's length is 5.6%; Step's speed is 13.5%	The use of IMU at CoM presents a good reliability for carrying out ambulatory, long-term, and ecologic kinematic of gait analysis
Saggio et al[36], 2020	7 IMU/pelvis, thighs, shanks and feet	Vicon	Joints ROMs RMSE and ICC PCC > 0.75, Reliability all the ICC > 0.975	IMUs sensors showed a high reliability on joints' movement and walking test

IMU: Inertial measurement unit; ICC: Intra-class correlation coefficients; RMSE: Root mean square error.