Incorporating Human-Like Walking Variability in an HZD-Based Bipedal Model

Anne E. Martin, Robert D. Gregg

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Predictive simulations of human walking could be used to investigate a wide range of questions. Promising moderately complex models have been developed using the robotics control technique called hybrid zero dynamics (HZD). Existing simulations of human walking only consider the mean motion; therefore, they cannot be used to investigate fall risk, which is correlated with variability. This study determines how to incorporate human-like variability into an HZD-based healthy human model to generate a more realistic gait. The key challenge is determining how to combine the existing mathematical description of variability with the dynamic model so that the biped is still able to walk without falling. To do so, the commanded motion is augmented with a sinusoidal variability function and a polynomial correction function. The variability function captures the variation in joint angles, while the correction function prevents the variability function from growing uncontrollably. The necessity of the correction function and the improvements with a reduction of stance ankle variability are demonstrated via simulations. The variability in temporal measures is shown to be similar to experimental values.

Original languageEnglish (US)
Article number7497008
Pages (from-to)943-948
Number of pages6
JournalIEEE Transactions on Robotics
Issue number4
StatePublished - Aug 2016

All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Computer Science Applications
  • Electrical and Electronic Engineering


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