Snakes use undulatory swimming to move efficiently through water, and different species show distinct patterns depending on their morphology and environment. With datasets available from live swimming tests and access to an undulatory robot, we can combine data analysis and physical experiments to explore their performance systematically and address biological questions.

Project Description:

The goal of this project is to analyse and replicate the diversity of swimming gaits in snakes using kinematic data from different species and a robot to explore insights into energy consumption. We’ll use reduced-order modelling to extract dominant motion patterns and look for structure in the data, for example, clustering gaits by species or lifestyle. Based on these results, we’ll test a few representative cases on a robotic platform to evaluate how well the robot can replicate biological gaits and how performance (e.g. speed, efficiency) varies with different strategies.

Specific Goals:

• Analyse snake swimming data to extract key gait parameters (e.g. curvature, amplitude, frequency)
• Perform reduced-order modelling to identify dominant gait modes.
• Cluster the gaits by species, morphology, or habitat.
• Select a few representative gaits and implement them on an undulatory robot.
• Run experiments to evaluate robotic performance across gaits.
• Compare biological and robotic results to identify general trends.

Pleurobot is a salamander-inspired robot that is capable of moving in and transitioning between terrestrial and aquatic environments. Some research projects in our lab have demonstrated the effectiveness of vision-guided or human-controlled locomotion transition strategies. However, the present Pleurobot is unable to use similar strategies robustly, especially in outdoor environments, because of lacking vision systems or robust wireless controllers.

In this project, the student will need to add vision systems (e.g., RGB-D camera) for Pleurobot that can operate in amphibious environments. In addition, a robust radio controller is needed to operate the robot in outdoor environments. Alternatively, the student can choose to implement algorithms for the vision system for recognizing terrain and obstacles in real-time. Both systems need to be integrated into the ROS 2 controller running on the onboard computer. The major challenges include the requirements for waterproofing, the limited space for electronics, and the fusion of multiple sensory systems in an embedded system.

The student is expected to have a solid background in circuit design for embedded systems, firmware programming, and familiarity with ROS 2. The student who is interested in this project could send his/her transcript, CV, and materials that can demonstrate his/her past project experience to qiyuan.fu@epfl.ch.

In nature, animals have many compliant structures that benefit their locomotion. For example, compliant foot/leg structures help adapt to uneven terrain or negotiate obstacles, flexible tails allow efficient undulatory swimming, and muscle-tendon structures help absorb shock and reduce energy loss. Similar compliant structures may benefit salamander-inspired robots as well.

In this study, the student will try simulating compliant structures (the feet of the robot) in Mujoco and optimizing the design. To bridge the sim-to-real gap, the student will first work with other lab members to perform experiments to measure the mechanical properties of a few simple compliant structures. Then, the student needs to simulate these experiments using the flexcomp plugin of Mujoco or theoretical solid mechanics models and tune the simulation models to match the dynamical response in simulation with the experiments. Afterward, the student needs to optimize the design parameters of the compliant structures in simulation to improve the locomotion performance of the robot while maintaining a small sim-to-real gap. Finally, prototypes of the optimal design will be tested on the physical robot to verify the results.

The student is thus required to be familiar with Python programming, physics engines (preferably Mujoco), and optimization/learning algorithms. The student should also have basic mechanical design abilities to design models and perform experiments. Students who have taken the Computational Motor Control course or have experience with data-driven design and solid mechanics would also be preferred.

The student who is interested in this project shall send the following materials to the assistants: (1) resume, (2) transcript showing relevant courses and grades, and (3) other materials that can demonstrate your skills and project experience (such as videos, slides, Git repositories, etc.).