High-Performance Hydraulic Soft Robotic Control Using Continuous Flow Regulation and Partial Feedback

Hydraulic-driven soft robots have received much less attention than their pneumatic counterparts. However, the incompressibility of liquid could bring a series of desirable attributes to soft robotic control, despite the apparent disadvantage of weight addition and compliance compromise resulting from the liquid medium itself, as well as the performance limitations of the hydraulic pump and valve systems being used. In this article, we introduce a Hydraulic Actuation with Wide-range Flow regulation (HAWF) as the fundamental inner control loop, and propose a soft robotic hydraulic control framework with Characteristics-based Control and Partial State feedback (CCPS), exploiting the desirable features of flow-regulating devices such as peristaltic pumps, achieving accurate and fast-responding position/force regulation on different soft actuators. The proposed control framework is validated with different control devices for comparisons, with promising results. The proposed framework could be generalizable to other hydraulic-driven systems towards control performance and simplified system setup across different applications.