On Designing Compliant Actuators Based On Dielectric Elastomers for Robotic Applications

Berselli, Giovanni; Vassura, Gabriele; Castelli, Vincenzo Parenti; Vertechy, Rocco

doi:10.5772/9311

Cited by 7 publications

(6 citation statements)

References 23 publications

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“…Emerging technologies, such as those based on electroactive polymers, can provide high power density with reasonable energy efficiency [22]. Dielectric elastomer-based linear actuators are interesting; however, their thrust profile can be improved in terms of stiffness characteristics [23]. These techniques are very promising, but no electroactive polymer has yet yielded a walk within a biped.…”

Section: Compliant Actuatorsmentioning

confidence: 99%

Muscle‐Like Compliance in Knee Articulations Improves Biped Robot Walkings

Serhan¹,

Hénaff²

2016

Recent Advances in Robotic Systems

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This chapter focuses on the compliance effect of dynamic humanoid robot walking. This compliance is generated with an articular muscle emulator system, which is designed using two neural networks (NNs). One NN models a muscle and a second learns to tune the proportional integral derivative (PID) of the articulation DC motor, allowing it to behave analogously to the muscle model. Muscle emulators are implemented in the knees of a three-dimensional (3D) simulated biped robot. The simulation results show that the muscle emulator creates compliance in articulations and that the dynamic walk, even in walk-halt-stop transitions, improves. If an external thrust unbalances the biped during the walk, the muscle emulator improves the control and prevents the robot from falling. The total power consumption is significantly reduced, and the articular trajectories approach human trajectories.

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Section: Compliant Actuatorsmentioning

confidence: 99%

Muscle‐Like Compliance in Knee Articulations Improves Biped Robot Walkings

Serhan¹,

Hénaff²

2016

Recent Advances in Robotic Systems

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“…The higher performance gain obtained for SIP-DEAs, with respect to circular-out-of-plane DEAs, can be explained by looking at typical force-displacement characteristics of the two actuator configurations. According to Berselli et al [28], the intersection points between force-displacement characteristics of the biasing mechanism and of the DEA, at different applied voltages, can be used to determine the actuator performance (see figure 2). Switching the voltage results in moving from one equilibrium position (intersection point) to the other one.…”

Section: Introductionmentioning

confidence: 99%

Silicone based dielectric elastomer strip actuators coupled with nonlinear biasing elements for large actuation strains

Hau

Bruch²,

Rizzello

et al. 2018

Smart Mater. Struct.

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There are two major categories of dielectric elastomer actuators (DEAs), which differ from the way in which the actuation is exploited: stack DEAs, using the thickness compression, and membrane DEAs, which exploit the expansion in area. In this work we focus on a specific type of membrane DEAs, i.e., silicone-based strip-in-plane (SIP) DEAs with screen printed electrodes. The performance of such actuators strongly depends on their geometry and on the adopted mechanical biasing system. Typically, the biasing is based on elastomer pre-stretch or on dead loads, which results in relatively low actuation strain. Biasing systems characterized by a negative rate spring have proven to significantly increase the performance of circular out-of-plane DEAs. However, this kind of biasing has never been systematically applied to silicone SIP DEAs. In this work, the biasing design based on negative rate springs is extended to strip DEAs as well, allowing to improve speed, strain, and force of the resulting actuator. At first, the DEAs are characterized under electrical and mechanical loading. Afterwards, two actuator systems are studied and compared in terms of actuation strain, force output, and actuation speed. In a first design stage, the DEA is coupled with a linear spring. Subsequently, the membrane is loaded with a combination of linear and nonlinear spring (working in a negative stiffness region). The resulting stroke output of the second systems is more than 9 times higher in comparison to the first one. An actuation strain of up to 45% (11.2 millimeter) and a force output of 0.38 Newton are measured. A maximum speed of 0.29 m s−1 is achieved, which is about 60 times faster than the one typically measured for similar systems based on VHB.

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“…been adopted in conjunction with DEs, e.g., pressured air [34], hydrostatic pressure [35], compliant frames [8,36], permanent magnets [37], or metal springs [38,39]. The biasing systems strongly affects the type of actuation output (in-plane or out-of-plane), as well as the amount of stroke/ force.…”

Section: Dielectric Elastomer Actuator Principlementioning

confidence: 99%

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

et al. 2022

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Background Dielectric elastomer (DE) transducers permit to effectively develop large-deformation, energy-efficient, and compliant mechatronic devices. By arranging many DE elements in an array-like configuration, a soft actuator/sensor system capable of cooperative features can be obtained. When many DE elements are densely packed onto a common elastic membrane, spatial coupling effects introduce electro-mechanical interactions among neighbors, which strongly affect the system actuation and sensing performance. To effectively design cooperative DE systems, those coupling effects must be systematically characterized and understood first. Objective As a first step towards the development of complex cooperative DE systems, in this work we present a systematic characterization of the spatial electro-mechanical interactions in a 1-by-3 array of silicone DEs. More specifically, we investigate how the force and capacitance characteristics of each DE in the array change when its neighbors are subject to different types of mechanical or electrical loads. Force and capacitance are chosen for this investigation, since those quantities are directly tied to the DE actuation and sensing behaviors, respectively. Methods An electro-mechanical characterization procedure is implemented through a novel experimental setup, which is specifically developed for testing soft DE arrays. The setup allows to investigate how the force and capacitance characteristics of each DE are affected by static deformations and/or electrical voltages applied to its nearby elements. Different combinations of electro-mechanical loads and DE neighbors are considered in an extensive experimental campaign. ResultsThe conducted investigation shows the existence of strong electro-mechanical coupling effects among the different array elements. The interaction intensity depends on multiple parameters, such as the distance between active DEs or the amount of deformation/voltage applied to the neighbors, and provides essential information for the design of array actuators. In some cases, such coupling effects may lead to changes in force up to 9% compared to the reference configuration. A further coupling is also observed in the DE capacitive response, and opens up the possibility of implementing advanced and/or distributed self-sensing strategies in future applications. Conclusion By means of the conducted experiments, we clearly show that the actuation and sensing characteristics of each DE in the array are strongly influenced by the electro-mechanical loading state of its neighbors. The coupling effects may significantly affect the overall cooperative system performance, if not properly accounted for during the design. In future works, the obtained results will allow developing cooperative DE systems which are robust to, and possibly take advantage of, such spatial coupling effects.

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On Designing Compliant Actuators Based On Dielectric Elastomers for Robotic Applications

Cited by 7 publications

References 23 publications

Muscle‐Like Compliance in Knee Articulations Improves Biped Robot Walkings

Muscle‐Like Compliance in Knee Articulations Improves Biped Robot Walkings

Silicone based dielectric elastomer strip actuators coupled with nonlinear biasing elements for large actuation strains

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

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