Lizards...

...co-design of robotic lizards at ETH Robotic Systems Lab


Lizard robots with three different morphologies: a low, an intermediate, and a high limb-to-body ratio, each with its own control policy to maximize cost of transport on flat ground.


The project is a collaboration between Prof. Marco Hutter and Prof. Baxi Chong (my former mentor at Dan Goldman’s lab). The objective of this project is to explore and optimize the morphological, control, and environmental parameter space in lizard-inspired robots, using simulation and learning, to optimize their speed, acceleration, and energetic cost across cluttered terrains, slopes, and sand.
The ultimate objectives are understanding evolutionary trends through a paleoinspired robotics approach (e.g. independently evolved limbless body forms), and especially informing the design of multi-modal robots that can adapt their morphology and control policies in real time to traverse diverse environments.


The video shows two sessions of a Tree-structured Parzen Estimator-based Bayesian Optimization for single-sized legged lizards to optimize the parameters of our wave-template controller.


Some of the parameters we have been exploring so far include, on the morphological side: limb-to-body ratio, limb DoFs, body/spinal DoFs, tail-to-body ratio…, while on the controls side: spinal undulation amplitude and phasing (wave shape), limb stepping wave amplitude and phasing, tail undulation amplitude and phasing, phasing between body, limbs, and tail, active vs passive tail… Finally on the environmental side we mainly explored flat terrains and slopes, and we are now just starting to test rugged terrains.


Performance difference of multiple-sized legged lizards using the exact same non-optimized gait.