@article{J21d,
title = {Design and Control of Pneumatic Systems for Soft Robotics: a Simulation Approach},
author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/06/J21d-Prepress.pdf},
doi = {10.1109/LRA.2021.3086425},
year = {2021},
date = {2021-06-04},
journal = {IEEE Robotics and Automation Letters},
volume = {Early Access},
abstract = {Pressure control plays a major role in the overall performance of fluid-driven soft robots. Due to the increasing demand for higher speed actuation and precision, a need exists for a practical design methodology that converts actuator performance specifications to a set of minimum pneumatic specifications, such as receiver volume and pressure, and valve conductance. This article presents a systematic parameter selection approach for pneumatic soft robotic systems by taking into consideration the desired closed-loop pressure responses. The two controllers under evaluation here are the PI controller with anti-windup and the on-off controller with hysteresis. Simulations are developed within Simscape Fluids to evaluate the effect of physical components and controller parameters on the actuator performance. The proposed parameter selection procedures are then applied on three soft actuators and their closed-loop pressure responses are experimentally evaluated. The measured pressure responses are in close agreement with the simulations and satisfy the rise time specifications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Moore2021,
title = {Serial-kinematic monolithic nanopositioner with in-plane bender actuators},
author = {S. I. Moore and Y. K. Yong and M. Omidbeike and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/03/J21c.pdf},
doi = {https://doi.org/10.1016/j.mechatronics.2021.102541},
isbn = {0957-4158},
year = {2021},
date = {2021-03-23},
journal = {Mechatronics},
volume = {75},
number = {102541},
abstract = {This article describes a monolithic nanopositioner constructed from in-plane bending actuators which provide greater deflection than previously reported extension actuators, at the expense of stiffness and resonance frequency. The proposed actuators are demonstrated by constructing an XY nanopositioning stage with a serial kinematic design. Analytical modeling and finite-element-analysis accurately predicts the experimental performance of the nanopositioner. A 10μm range is achieved in the X and Y axes with an applied voltage of +/-200 V. The first resonance mode occurs at 250 Hz in the Z axis. The stage is demonstrated for atomic force microscopy imaging.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J21b,
title = {Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments},
author = {M. S. Xavier and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/02/J21b.pdf},
doi = {10.1002/aisy.202000187},
isbn = {2640-4567},
year = {2021},
date = {2021-02-01},
journal = {Advanced Intelligent Systems},
volume = {3},
number = {2},
pages = {2000187},
abstract = {Many soft robots are composed of soft fluidic actuators that are fabricated from silicone rubbers and use hydraulic or pneumatic actuation. The strong nonlinearities and complex geometries of soft actuators hinder the development of analytical models to describe their motion. Finite element modeling provides an effective solution to this issue and allows the user to predict performance and optimize soft actuator designs. Herein, the literature on a finite element analysis of soft actuators is reviewed. First, the required nonlinear elasticity concepts are introduced with a focus on the relevant models for soft robotics. In particular, the procedure for determining material constants for the hyperelastic models from material testing and curve fitting is explored. Then, a comprehensive review of constitutive model parameters for the most widely used silicone rubbers in the literature is provided. An overview of the procedure is provided for three commercially available software packages (Abaqus, Ansys, and COMSOL). The combination of modeling procedures, material properties, and design guidelines presented in this article can be used as a starting point for soft robotic actuator design.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ruppert2021,
title = {Active atomic force microscope cantilevers with integrated device layer piezoresistive sensors},
author = {M. G. Ruppert and A. J. Fleming and Y. K. Yong},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/01/J21a.pdf},
doi = {10.1016/j.sna.2020.112519},
year = {2021},
date = {2021-01-19},
journal = {Sensors & Actuators: A. Physical},
abstract = {Active atomic force microscope cantilevers with on-chip actuation and sensing provide several advantages over
passive cantilevers which rely on piezoacoustic base-excitation and optical beam deflection measurement. Active
microcantilevers exhibit a clean frequency response, provide a path-way to miniturization and parallelization and
avoid the need for optical alignment. However, active microcantilevers are presently limited by the feedthrough
between actuators and sensors, and by the cost associated with custom microfabrication. In this work, we propose
a hybrid cantilever design with integrated piezoelectric actuators and a piezoresistive sensor fabricated from the
silicon device layer without requiring an additional doping step. As a result, the design can be fabricated using a
commercial five-mask microelectromechanical systems fabrication process. The theoretical piezoresistor sensitivity
is compared with finite element simulations and experimental results obtained from a prototype device. The
proposed approach is demonstrated to be a promising alternative to conventional microcantilever actuation and
deflection sensing},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{J20h,
title = {Position and force sensing using strain gauges integrated into piezoelectric bender electrodes},
author = {R. Seethaler and S. Z. Mansour and M. G. Ruppert and A. J. Fleming},
url = {http://www.precisionmechatronicslab.com/wp-content/uploads/2021/01/J20h-prepress-2.pdf},
doi = {10.1016/j.sna.2020.112416},
isbn = {0924-4247},
year = {2020},
date = {2020-12-30},
journal = {Sensors and Actuators A: Physical},
pages = {112416},
abstract = {This article derives design guidelines for integrating strain gauges into the electrodes of piezoelectric bending actuators. The proposed sensor can estimate the actuator tip displacement in response to an applied voltage and an external applied tip force. The actuator load force is also estimated with an accuracy of 8% full scale by approximating the actuator response with a linear model. The applications of this work include micro-grippers and pneumatic valves, which both require the measurement of deflection and load force. At present, this is achieved by external sensors. However, this work shows that these functions can be integrated into the actuator electrodes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}