In context
As deep space missions expand—following Chang'e-6's lunar far-side sample return and Tianwen-1's Mars landing—planetary surface exploration demands robots capable of traversing challenging terrains like craters and dunes. Traditional wheeled rovers are limited to flat areas, prompting interest in spherical robots that offer unique mobility and resilience.
What was reported
The review categorizes spherical robot configurations based on shell structure: spherical, ellipsoidal, deformable, and tensegrity designs. Spherical shells provide collision recovery, anti-overturning on slopes, and omnidirectional movement, while ellipsoidal shells accommodate more sensors and offer better acceleration in one direction. Deformable shells, such as those with legs or expanding hemispheres, enable multi-mode locomotion, and tensegrity structures like NASA's Super Ball Bot combine lightweight with impact absorption for landing and rolling.
Drive modes are classified into rolling, jumping, flying, and hybrid. Rolling includes passive wind-driven systems like “tumbleweed” robots, which exploit Martian winds (5–20 m/s, gusts to 40 m/s) for energy-efficient travel, and active drives such as friction (unicycle or “hamster ball”), gravity (pendulum or mass), angular momentum, and shell-based mechanisms. Examples include JPL's Moball, which harvests wind energy for self-powering, and the BHQ-3 robot capable of climbing 17° slopes and overcoming 30 mm obstacles.
Key technologies for planetary application are discussed, emphasizing the need for robustness in extreme environments. The paper notes that while spherical robots offer advantages in energy efficiency and terrain adaptability, challenges remain in control, slip on rough terrain, and integration of scientific instruments.
Why it mattered
This review consolidates progress in spherical robot technology, highlighting its potential for future planetary missions requiring wide-area surveys and access to difficult terrains. It provides a reference for developing robots that balance mobility, energy efficiency, and durability, which could extend the reach of automated exploration on the Moon, Mars, and beyond.
“Spherical robots have great potential in deep space exploration tasks such as surface exploration on planets.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2025-11-19 · “面向星表探测的球形机器人研究进展”