A trial of making reference gait data for simple gait evaluation system with wireless inertial sensors

Evaluation of Validity and Reliability of Inertial Measurement Unit-Based Gait Analysis Systems

Objective

To replace camera-based three-dimensional motion analyzers which are widely used to analyze body movements and gait but are also costly and require a large dedicated space, this study evaluates the validity and reliability of inertial measurement unit (IMU)-based systems by analyzing their spatio-temporal and kinematic measurement parameters.

Methods

The investigation was conducted in three separate hospitals with three healthy participants. IMUs were attached to the abdomen as well as the thigh, shank, and foot of both legs of each participant. Each participant then completed a 10-m gait course 10 times. During each gait cycle, the hips, knees, and ankle joints were observed from the sagittal, frontal, and transverse planes. The experiments were conducted with both a camerabased system and an IMU-based system. The measured gait analysis data were evaluated for validity and reliability using root mean square error (RMSE) and intraclass correlation coefficient (ICC) analyses.

Results

The differences between the RMSE values of the two systems determined through kinematic parameters ranged from a minimum of 1.83 to a maximum of 3.98 with a tolerance close to 1%. The results of this study also confirmed the reliability of the IMU-based system, and all of the variables showed a statistically high ICC.

Conclusion

These results confirmed that IMU-based systems can reliably replace camera-based systems for clinical body motion and gait analyses.

A preliminary study on evaluation of circumduction movement during gait with wireless inertial sensors

Recently, inertial sensors have been used to measure human movements for the purpose of rehabilitation. In evaluation of motor function for rehabilitation, reference data measured from healthy subjects with inertial sensors is needed. In addition, since lower limbs perform 3-dimensional movements during gait, it is needed to analyze 3-dimensional gait movements. The plot of 3-dimensional vector locus can be useful to understand 3-dimensional movements. The purposes of this paper were to show usefulness of the vector locus in understanding circumduction during gait, and to test an evaluation parameter for 3-dimensional movements during walking as reference data. Gait of 12 healthy subjects were measured, and then vector loci were plotted in the 3-dimensional space. Shape of the vector locus was evaluated by the width of each component as one of the reference data. It was suggested that the vector loci plotted in 3-dimensioinal space or those projected on horizontal plane were useful to understand circumduction during gait. It was also suggested that the width of vector locus was useful to evaluate differences of movement between subjects.