1.Introduction
Multi-chamber soft pneumatic actuators (m-SPAs) are promising in the applications of soft machines and robots, including rotators \cite{Ainla.2017}, oscillators \cite{Preston.2019}, grippers \cite{Shintake.2018,Gong.2021,Low.2020}, robotic hands \cite{Gu.2021,Deimel.2016}, gloves \cite{Feng.2021,Connolly.2019,Yun.2017}, snake-inspired robots \cite{Qi.2020,Luo.2014}, bioinspired robotic fish \cite{Marchese.2014}, multi-legged robots \cite{Drotman.2021,Drotman.2017,Wehner.2016,Tolley.2014,Shepherd.2011}, and soft functional arrays \cite{Hashem.2021,Hashem.2021b,Robertson.2017}. Increasing the speed and reducing the energy consumption of m-SPAs could lead to more steady, reliable, and robust performance \cite{Ainla.2017,Marchese.2014,Tolley.2014,Aubin.2022,Gorissen.2017,Polygerinos.2017,Xavier.2022}. However, most existing architectures are designed with limited consideration of actuation speed and energy consumption and instead generally focus on other performance metrics related to versatile degree-of-freedoms \cite{Wang.2021}, larger working space \cite{Chen.2021,Ke.2021}, higher force \cite{Yap.2016,Li.2020}, or smarter perception \cite{Takaki.2019,Zoller.2018,Giffney.2016}.