E	Young’s modulus
${\sigma }_0$	yield stress
P	pressure inside the actuator
e	distance from the neutral axis to the centroid
I	area moment of inertia with respect to the neutral axis
$I_0$	area moment of inertia with respect to the centroid
$A_0$	cross-sectional area of the polymer tube
A	cross-sectional area of the pressurized volume of the polymer tube
L	length of the polymer tube
$\delta L$	elongation of the polymer tube
R	internal radius of the polymer tube
t	thickness of the polymer tube
$\alpha$	angular width of the polymer patch
T	thickness of the polymer patch
$\vartheta$	bending angle of the actuator