Jerboa Gait Transition

Paper: “A Template Model Explains Jerboa Gait Transitions Across a Broad Range of Speeds”

Authors: Jiayu Ding, Talia Y. Moore, and Zhenyu Gan
Journal: Frontiers in Bioengineering and Biotechnology, 2022

This study investigates how non-cursorial bipedal animals, specifically jerboas, transition between different gaits across a broad range of speeds. Jerboas are desert rodents that hop on their hind legs and are capable of frequent transitions between hopping, skipping, walking, and running. The research combines experimental kinematic and dynamic data from captive jerboas with a novel spring-loaded inverted pendulum (SLIP) model that incorporates passive swing leg motion controlled by torsional springs. Unlike previous models, this approach allows the emergence of various gaits and transitions by altering model parameters, rather than prescribing footfall sequences.

Through systematic optimization and numerical continuation, the model successfully reproduces all major gait patterns observed in jerboas and predicts the occurrence of new asymmetrical running gaits. Two primary mechanisms for inducing gait transitions are identified: (1) coupled changes in the neutral leg swing angle, which shift the speeds at which transitions occur, and (2) uncoupling the left and right neutral leg swing angles, which enables asymmetry and new gait transitions across a wide range of speeds. Model predictions are validated with empirical data, demonstrating close agreement between simulated and real jerboa gait transitions.

This work provides new insight into the dynamics of bipedal gait switching in animals and offers practical tools for designing legged robots with smooth, energy-efficient gait transitions across varying speeds.

The apex transitions, touchdowns, and liftoffs for one stride of four different gait patterns are demonstrated by jerboas on the left, with inset gait diagrams showing footfall patterns, and the corresponding simulated gait patterns using the model are shown on the right. The right leg of the jerboa is shown in white and the left leg is in the same color as the corresponding gait branches in the inset diagram. The left leg of the model is shown in grey and the right leg is in white. (A) Hopping, in which both feet strike and lift off simultaneously. (B) Skipping, with overlapping but non-simultaneous foot strikes. (C) Asymmetrical running, with two different aerial phases. (D) Symmetrical running, which contains two aerial phases with approximately the same duration. Blue curved arrows indicate leg touchdown (\( t_\text{td,i} \)), and gray curved arrows denote liftoff events (\( t_\text{lo,i} \)).

Access the Jerboa model and dataset here

Reference

@article{ding2022template,
title={A Template Model Explains Jerboa Gait Transitions Across a Broad Range of Speeds},
author={Ding, Jiayu and Moore, Talia Y. and Gan, Zhenyu},
journal={Frontiers in Bioengineering and Biotechnology},
volume={10},
pages={804826},
year={2022},
doi={10.3389/fbioe.2022.804826},
url={https://www.frontiersin.org/articles/10.3389/fbioe.2022.804826/full}
}