Describing gait as a sequence of states

Area of Science:

• Biomechanics
• Human Movement Analysis
• Signal Processing

Background:

• Traditional gait analysis normalizes stride time to a percentage and averages strides.
• This method assumes gait is cyclic with noise, ignoring timing and angle variability.
• Time-rescaling in traditional methods increases joint angle standard deviation with angular velocity.

Purpose of the Study:

• To present a gait description method that avoids averaging and preserves original curve data.
• To enable analysis of fluctuations between consecutive strides.
• To develop a method for analyzing quasi-periodic movements like gait.

Main Methods:

• Assumes gait is quasi-periodic.
• Represents gait using a time-evolving state vector.
• Calculates instantaneous period and measures time fluctuations between strides using the sequence of states method.

Main Results:

• The sequence of states method provides a continuous estimate of gait cycle time.
• This method quanties deviations between gait cycles.
• It avoids the distortions associated with traditional averaging and time-rescaling techniques.

Conclusions:

• The sequence of states method offers a more accurate representation of gait dynamics.
• It allows for detailed analysis of stride-to-stride variability.
• This approach advances the understanding of quasi-periodic human movements.