Linear-Quadratic Regulator for Control of Multi-Wall Carbon Nanotube/Polydimethylsiloxane Based Conical Dielectric Elastomer Actuators

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.

[1]  D. Leo,et al.  Feedback Control of Resonant Modes in Bending Response of Ionic Polymer Actuators , 2001, Adaptive Structures and Material Systems.

[2]  P. McHugh,et al.  A review on dielectric elastomer actuators, technology, applications, and challenges , 2008 .

[3]  Sebastien Carriere,et al.  Optimal LQI Synthesis for Speed Control of Synchronous Actuator under Load Inertia Variations , 2008 .

[4]  S. Michel,et al.  Stacked dielectric elastomer actuator for tensile force transmission , 2009 .

[5]  Ajit Khosla,et al.  Preparation, characterization and micromolding of multi-walled carbon nanotube polydimethylsiloxane conducting nanocomposite polymer , 2009 .

[6]  Q. Pei,et al.  Advances in dielectric elastomers for actuators and artificial muscles. , 2010, Macromolecular rapid communications.

[7]  Samuel Rosset,et al.  Self-sensing dielectric elastomer actuators in closed-loop operation , 2013 .

[8]  Micah Hodgins,et al.  An electro-mechanically coupled model for the dynamic behavior of a dielectric electro-active polymer actuator , 2014 .

[9]  Alexandre Poulin,et al.  Printing low-voltage dielectric elastomer actuators , 2015 .

[10]  D. Rus,et al.  Design, fabrication and control of soft robots , 2015, Nature.

[11]  Ron Pelrine,et al.  Standards for dielectric elastomer transducers , 2015 .

[12]  Micah Hodgins,et al.  A smart experimental technique for the optimization of dielectric elastomer actuator (DEA) systems , 2015 .

[13]  Thorben Hoffstadt,et al.  Self-sensing Algorithms for Dielectric Elastomer Multilayer Stack-Transducers , 2016 .

[14]  Stefan Seelecke,et al.  Robust Position Control of Dielectric Elastomer Actuators Based on LMI Optimization , 2016, IEEE Transactions on Control Systems Technology.

[15]  Samuel Rosset,et al.  Small, fast, and tough: Shrinking down integrated elastomer transducers , 2016 .

[16]  Rahimullah Sarban,et al.  Model validation and feedback controller design for a dielectric elastomer actuator , 2016 .

[17]  Francesco Branz,et al.  Modelling and control of double-cone dielectric elastomer actuator , 2016 .

[18]  Mark Stewart,et al.  Electrical breakdown of dielectric elastomers: influence of compression, electrode's curvature and environmental humidity , 2016, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[19]  Limin Zhu,et al.  Open-Loop Control of Creep and Vibration in Dielectric Elastomer Actuators With Phenomenological Models , 2017, IEEE/ASME Transactions on Mechatronics.

[20]  Xiangyang Zhu,et al.  A survey on dielectric elastomer actuators for soft robots , 2017, Bioinspiration & biomimetics.

[21]  Micah Hodgins,et al.  Effect of screen printing parameters on sensor and actuator performance of dielectric elastomer (DE) membranes , 2017 .

[22]  Xiangyang Zhu,et al.  Modeling of Viscoelastic Electromechanical Behavior in a Soft Dielectric Elastomer Actuator , 2017, IEEE Transactions on Robotics.

[23]  Micah Hodgins,et al.  Design and Control of a High-Speed Positioning System Based on Dielectric Elastomer Membrane Actuators , 2017, IEEE/ASME Transactions on Mechatronics.

[24]  Stefan Seelecke,et al.  A novel dielectric elastomer membrane actuator concept for high-force applications , 2018, Extreme Mechanics Letters.

[25]  Stefan Seelecke,et al.  Simultaneous Self-Sensing of Displacement and Force for Soft Dielectric Elastomer Actuators , 2018, IEEE Robotics and Automation Letters.

[26]  J. Zou,et al.  Modeling the Viscoelastic Hysteresis of Dielectric Elastomer Actuators with a Modified Rate-Dependent Prandtl–Ishlinskii Model , 2018, Polymers.

[27]  T. Mulembo,et al.  Conductive and flexible multi‐walled carbon nanotube/polydimethylsiloxane composites made with naphthalene/toluene mixture , 2019, Journal of Applied Polymer Science.

[28]  Jiang Zou,et al.  High-Precision Tracking Control of a Soft Dielectric Elastomer Actuator With Inverse Viscoelastic Hysteresis Compensation , 2019, IEEE/ASME Transactions on Mechatronics.

[29]  Fucai Li,et al.  Hysteresis compensation control of a dielectric elastomer vibration isolator , 2019 .