Abstract:
Conventional rigid actuators, such as DC servo motors, face challenges in utilizing them
in artificial muscles and soft robotics. Dielectric elastomer actuators (DEAs) overcome all these
limitations, as they exhibit complex and fast motions, quietness, lightness, and softness. Recently, there
has been much focus on studies of the DEAs material’s non-linearity, the non-linear electromechanical
coupling, and viscoelastic behavior of VHB and silicone-based conical DEAs having compliant
electrodes that are based on graphite powder and carbon grease. However, the mitigation of
overshoot that arises from fast response conical DEAs made with solid electrodes has not received
much research focus. In this paper, we fabricated a conical configuration of multi-walled carbon
nanotube/polydimethylsiloxane (MWCNT/PDMS) based DEAs with a rise time of 10 ms, and 50%
peak overshoot. We developed a full feedback state-based linear-quadratic regulator (LQR) having
Luenberger observer to mitigate the DEAs overshoot in both the voltage ON and OFF instances. The
cone DEA’s model was identified and a stable and well-fitting transfer function with a fit of 94%
was obtained. Optimal parameters Q = 70,000, R = 0.1, and Q = 7000, R = 0.01 resulted in the DEA
response having a rise time value of 20 ms with zero overshoot, in both simulations and experiments.
The LQR approach can be useful for the control of fast response DEAs and this would expand the
potential use of the DEAs as artificial muscles in soft robotics.
