Abstract
New mechanism paradigms are needed to improve robot performance and resilience in harsh environments. Soft continuous mechanisms can be simpler and more robust than the stiff-discrete assemblies traditionally found in robotics. Herein, a methodology to design underactuated soft robots is presented and its application to fish-like robots is outlined. The principle is simple, a flexible viscoelastic continuous body is designed with the appropriate material heterogeneity such that dominant modes of vibration match desired body motions. Design examples are given for different fish-like robots and actuation units. Fabrication techniques and testing procedures are presented along with locomotion performance. The approach is general and can be applied to bodies with more complex target kinematics and offers a promising alternative for mobile robots.