skdh.gait.StepRegularityV

class skdh.gait.StepRegularityV

The autocovariance at a lag time of 1 step for the vertical acceleration. Computed for an entire bout of gait, it is a measure of the average symmetry of sequential steps during overground strait gait. Values close to 1 indicate high degree of regularity/symmetry, while values close to 0 indicate a low degree of regularity/symmetry.

Methods

predict(*, fs, leg_length, gait, gait_aux)

Predict the bout level gait endpoint

Notes

If the minimum gait window time is less than 4.5 seconds, there may be issues with this endpoint for those with slow gait (those with stride lengths approaching the minimum gait window time).

Step regularity is the value of the autocovariance function at a lag equal to the time for one step. While [2] uses the autocorrelation instead of the autocovariance like [1], the autocovariance is used here as it provides a mathematically better comparison of the acceleration profile during gait.

The peak corresponding to one step time is found by searching the area near the lag corresponding to the average step time for the gait bout. The nearest peak to this point is used as the peak at a lag of one step.

References

[1]

R. Moe-Nilssen and J. L. Helbostad, “Estimation of gait cycle characteristics by trunk accelerometry,” Journal of Biomechanics, vol. 37, no. 1, pp. 121–126, Jan. 2004, doi: 10.1016/S0021-9290(03)00233-1.

[2]

C. Buckley et al., “Gait Asymmetry Post-Stroke: Determining Valid and Reliable Methods Using a Single Accelerometer Located on the Trunk,” Sensors, vol. 20, no. 1, Art. no. 1, Jan. 2020, doi: 10.3390/s20010037.