Hybrid dynamic model for shape memory alloy linear and unimorph actuators

Shape memory alloy morphing actuators are a type of soft actuator with
many attractive properties. These actuators exhibit large deformation,
small form factor, self-sense ability, and physical reservoir computing
potential, while also being inexpensive. These morphing actuators are
composed of active shape memory alloy wires and a passive base layer that
is used to magnify the overall deflection. Although morphing actuators
have great potential, the modeling of shape memory alloy actuators is
difficult due to both shape memory alloy characteristics and the
nonlinearity of the passive layer. Here, a hybrid dynamical model is
proposed that couples the phase kinetics & thermal modeling for
the shape memory alloy with a dynamic Cosserat nonlinear beam model. This
hybrid model is benchmarked against linear and morphing experimental
actuators. The model resulted in a root mean squared error of 1.48 mm and
1.63 mm for the morphing actuator configuration for two different
actuators. This model can expand the capability and design of novel
morphing actuators for a designed deformation profile for use in soft
robotics.