# Actuation Mechanisms and Applications for Soft Robots: A Comprehensive Review
## 4 Further Discussions
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Actuations** & **Advantages** & **Disadvantages** & **Applications** \\ \hline \multirow{4}{*}{Shape Memory Alloys (SMAs)} & High thermal stability. & \multirow{4}{*}{Shlow response.} \\  & Recoverable strain. & & \\  & Strong corrosion resistance. & & High energy consumption \\  & Easy to automate. & & and low efficiency. \\  & Able to be additively & & Affected by temperature. \\  & manufactured. & & \\ \hline \multicolumn{2}{c}{Fluids} & \\ \hline \multirow{2}{*}{Pneumatic [191; 192; 193; 194]} & Fast response. & \multirow{2}{*}{\begin{tabular}{c} Need external air pumps. \\ Difficult to miniaturize. \\ \end{tabular} } \\  & High security. & & Difficult to miniaturize. \\  & Strong flexibility. & & \\ \hline \multirow{2}{*}{Origami-based Pneumatic [100]} & Low cost. & \multirow{2}{*}{\begin{tabular}{c} Easy to be vulnerable. \\ Low reuse rate. \\ \end{tabular} } \\  & Light weight. & & \\  & Quick response. & & Low reuse rate. \\  & Able to be programmable. & & Swimming robot. \\ \hline \multirow{2}{*}{Hydraulic [195; 107]} & Good driving force. & \multirow{2}{*}{\begin{tabular}{c} Large weight. \\ Complex structural elements. \\ Inconvenient to maintain. \\ \end{tabular} } \\  & Both pneumatic and hydraulic & & Difficult to miniaturize. \\  & advantages. & & \\ \hline \multicolumn{2}{c}{Electroactive polymers (EAPs)} & \\ \hline \multirow{4}{*}{Electronic [196; 197; 198]} & High energy density. & \multirow{2}{*}{\begin{tabular}{c} Robot gripper. \\ Creeping, underwater, \\ aerial robots. \\ Soft actuators such as \\ Artificial muscles. \\ \end{tabular} } \\  & Quick response. & & \\  & Long operating time. & & \\  & Able to perceive itself. & & \\ \hline \multirow{2}{*}{Ionic [10, 199]} & Low driving voltage. & \multirow{2}{*}{\begin{tabular}{c} Response time is longer than \\ electronic. \\ Small output force. \\ \end{tabular} } \\  & Large bending displacement. & & \\  & & & \\ \hline \multirow{2}{*}{Electric \& Magnetic [200; 201; 202]} & Automatic control. & \multirow{2}{*}{\begin{tabular}{c} Large external coil that \\ generates the magnetic field. \\ High power consumption. \\ Small controllable area. \\ \end{tabular} } \\  & & & \\  & & & \\ \hline \multirow{4}{*}{Light [128; 133]} & \multirow{4}{*}{\begin{tabular}{c} Able to be controlled \\ wirelessly and remotely. \\ Easy to miniaturize. \\ Have access to \\ human-computer interaction. \\ \end{tabular} } \\  & & & \\ \hline \multirow{2}{*}{Sound [203]} & Transfer energy through & \multirow{2}{*}{\
\begin{tabular}{c} Vulnerable to external \\ unrequired noise. \\ Limited mobility. \\ \end{tabular} } \\  & In-module communication. & & Limited mobility. \\ \hline \multirow{4}{*}{Chemical [164; 204]} & High energy density. & \multirow{2}{*}{
\begin{tabular}{c} Need to be refueled regularly. \\ High requirements for impact \\ resistance of materials. \\ \end{tabular} } \\  & Quick response. & & \\ \cline{1-1}  & Unthered. & & \\ \cline{1-1}  & Greater obstacle avoidance & & \\ \cline{1-1}  & capability. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of various actuation mechanisms.