Here is a clever shape changing variable stiffness wheeled robot that can adapt to uneven terrain. Korea Institute of Machinery and Materials researchers have developed a wheel with adjustable stiffness that can roll over large obstacles and operate on flat surfaces by changing shape. It has a spoke structure with adjustable tension.
The above video shows this clever wheelchair in action. The team also developed a 4-wheeled vehicle based on this concept.
[Credit: Jae-Young Lee, Seongji Han, Munyu Kim , Yong-Sin Seo, Jongwoo Park, Dong Il, Chanhun Park, Hyunuk Seo, Joonho Lee, Hwi-Su Kim, Jeongae Bak, Hugo Rodrigue , Jin-Gyun Kim, Joono Cheong, and Sung-Hyuk Song][HT]