New Honeycomb-Structured Pneumatic Quadruped Soft Robot: Design & Control

What is it about?

Inspired by the flexible structures of soft-bodied creatures like octopuses and earthworms, researchers have begun developing new soft robots using various flexible materials. Compared to traditional rigid robots, soft robots have several advantages: they are lightweight, have high flexibility in movement, and are safer when interacting with humans. However, designing new types of quadruped soft robots has always been a significant challenge. To address this issue, we’ve proposed a brand-new design and control methodology for developing a pneumatically driven quadruped soft robot—its core features a highly deformable hexagonal structure, paired with a special shape-retaining material.Our work was carried out in three main steps: First, the robot’s overall design. We referenced the movement mechanisms of real quadruped animals (such as cats and dogs) and combined them with the deformation principle of hexagonal cells in honeycombs to design the robot’s leg structure. We also created a matching pneumatic actuator based on the pneumatic drive method—with this actuator, the robot’s legs can perform movements like stretching and bending. Second, mathematical modeling and computer simulation. Using geometric analysis, we built two mathematical models: one to describe the deformation rules of the hexagonal cells, and another to calculate how much a single leg can stretch. We then used computer simulation (the layman’s term for "finite element simulation") to verify if these models were accurate, ensuring that theoretical calculations matched real-world deformation. Third, experimental testing. We conducted a series of experiments: first, we tested the performance of a single leg, including its static stability, how much force it could exert, and its maximum range of motion. Then, we programmed the control logic and had the full quadruped robot attempt to walk in straight lines and curves—both were successful. In short, the methodology we proposed provides an efficient and practical new approach for the design of quadruped soft robots.

Featured Image

Why is it important?

The paper breaks through the traditional design for the leg structure of quadruped soft robots and combines two sources of inspiration: on the one hand, it draws on the movement mechanisms of real quadruped animals (such as the leg movement logic of cats, dogs, etc.) to ensure the biological rationality of the robot's walking; on the other hand, it introduces the deformation concept of honeycomb hexagonal chambers and takes this as the core of the leg structure — the hexagonal structure itself has both "high deformability" and "structural stability", and when paired with "shape-preserving material properties", it can not only achieve the flexible stretching and bending required by soft robots, but also maintain the necessary shape support after deformation (avoiding motion loss control caused by excessive deformation). This integrated design of "biological movement logic + engineering structural advantages" is its core innovation at the structural level. The paper does not propose a single design detail in a fragmented way, but constructs a closed-loop and reusable design methodology for quadruped soft robots: from the scheme design of "dual-inspiration-based leg structure + matching pneumatic actuator", to the theoretical verification of "geometric analysis modeling + finite element simulation verification", and then to the physical implementation of "single-leg performance testing + straight-line/curve walking experiments", forming a complete R&D chain "from concept to practical application". This systematic methodology differs from the limitations of "emphasizing design over verification" or "valuing simulation over physical implementation" in traditional research, endowing the design idea with stronger replicability and engineering value.