An Active Spring Mass Model With Biomimetic Ground Reaction Forces for Multiple Terrains

Area of Science:

• Biomechanics and Robotics
• Human Locomotion Analysis
• Assistive Device Control

Background:

• Human locomotion involves diverse activities like walking on level ground, stairs, and slopes.
• Predicting human movement is crucial for designing lower-limb assistive devices.
• Existing gait models primarily focus on level-ground walking dynamics.

Purpose of the Study:

• Develop a conceptual gait model capable of simulating level ground, stair, and slope negotiation (up to +/- 42 degrees).
• Ensure the model generates biomimetic ground reaction forces (GRFs) comparable to human data.

Main Methods:

• Extended a passive bipedal spring mass model by integrating active elements and seven control parameters.
• Tuned these parameters to accurately replicate human GRFs during stair walking.
• Performed parameter analysis to understand their influence on GRFs.

Main Results:

• Optimized model demonstrated strong correlation with human GRFs for stair walking (median R_x > 0.89, R_y > 0.96).
• Model successfully mimicked human GRFs during slope walking.
• Identified a reduced five-parameter model retaining high fidelity in GRF prediction.

Conclusions:

• The developed gait model enhances prediction of human locomotion across varied terrains.
• This model can inform the control strategies for powered lower-limb exoskeletons and prostheses, particularly for foot placement planning.