Effects of Friction Anisotropy on Upward Burrowing Behavior of Soft Robots in Granular Materials. - Sichuan Huang; Yong Tang; Hosain Bagheri; Dongting Li; Alexandria Ardente; Daniel Aukes; Hamidreza Marvi 001; Junliang (Julian) Tao (Adv. Intell. Syst., 2020)