Towards Understanding How to Design a Soft Artificial Muscle Actuator?

In this manuscript we present a physics based model for sake of understandingthe actuation mechanism and the desired blocked force generated with respectto the applied potential field at different geometries.In the experimental work, we have found that the frequency and the am-plitude plays a crucial role in actuation profile of ionic EAP. For estimatingthe blocked force generated along the spatial domain of ionic EAP, we haveimplemented Coulomb inverse square law as there is an electrostatic interactionamong one mobile ion and N of elementary electric charge which could be re-pulsion or attraction on both surface area of ionic EAP based on the appliedpotential field phase.The ionic EAP is a tri-layer, assuming that the upper and lower layer whichare conductive layer a RC transmission line where we assume that R is constantfor sake of simplicity. The potential field at the clamping point is diffused alongthe muscle, one dimensional diffusion model is implemented for estimating theelementary electric charges diffused in the surface area of the upper layer. Asionic EAP is working as mutual capacitor, we have assumed that the chargesof the stored mobile ions in the medium layer has the same initial value of theelementary electric charges in the upper and conductive layer.After estimating the spatial charge of the electrons and ions, the stress-charge coupling is multiplied with the estimated value for having the value ofstress, force, strain, and curvature which is important for designing coupledactuators.Following, we have simulated forward and inverse approaches for estimatingthe force and the desired potential field in each case for a coupled actuators.The stress charge coupling can estimate the steady state final value of thegenerated force, however, it doesnot capture the stress relaxation behavior orsaturation phenomena occurs during the low frequency. We believe that under-standing the physics behind the actuation of ionic EAP artificial muscle couldlead us to design a desired artificial muscle for specific application and improvingtheir mechanical properties and response time as well.1