1,720,995 research outputs found
Integrated force and displacement sensing in an untethered dielectric elastomer actuator with a piezoresistive element
No full textDielectric elastomer actuators, owing to their fully electrical control and silent operation, are becoming increasingly popular for the development of terrestrial and underwater mobile robots with versatile locomotion capabilities. It is essential to embed the ability to sense their state and external interactions in these robots to facilitate the development of future autonomous capabilities. However, sensorizing dielectric elastomer actuators for untethered robotic applications is challenging due to their use of high voltage and the nonlinear mechanics of the elastomers utilized in them. To address this challenge, we developed a novel technique based on embedded piezoresistive sensing and high voltage feedback to simultaneously estimate the actuator displacement and external force in a fully untethered actuator driven by a miniature low-cost voltage amplifier. A data-driven regression model has been developed to accurately estimate force and displacement from the measured data. Validation tests conducted on three actuators demonstrate promising results. We achieve RMSE values as low as 29.736 mN for force estimation and 0.023 mm for displacement estimation in the zero-voltage condition, where the actuator is subjected to a triangular wave with a mechanical frequency of 0.1 Hz and an amplitude of 3 mm. Additionally, we have realized fully untethered operation by employing a power source, small-size voltage amplifier, microcontroller, and wireless connectivity module embedded in a compact form-factor. This work presents a significant advancement in soft robotics, offering a reliable and cost-effective solution for future autonomous robotic systems based on high-voltage dielectric elastomer actuators
Multistable states and snap-through instabilities in an interconnected dielectric elastomer actuators system
No full textSnap-through instabilities in single and interconnected dielectric elastomer actuators have demonstrated their potential in enabling many functionalities such as large deformation, high-speed actuation, and enhanced flowrates in fluid pumps. However, the nonlinear nature of dielectric elastomers and the complex interplay of mechanics in interconnected inflated actuators, make the modeling of such systems challenging. In this paper, we present a methodology to analytically model the instabilities in a system of three interconnected homogeneous spherical dielectric elastomer actuators through graphical and numerical approaches. The simulation results reveal the presence of a locus of initial stable states that the interconnected actuators can achieve at zero voltage. In specific loading conditions, the system exhibits multiple stable states which can be cyclically transitioned between by selectively applying voltage to specific actuators. In other conditions, the system may undergo two successive instabilities when the voltage applied to a single actuator in the system is increased monotonically. These results retrieve existing experimental results theoretically for the first time and identify a new behavior of cascading instabilities in inflated dielectric elastomer actuators. We hope this work will pave the way for programmable design of multistable systems to unravel new capabilities in dielectric elastomer actuators and soft robotics
An electro-pneumatic shape morphing rolling robot with variable locomotion modes
No full textMobile robots with accurate and fast rolling loco-motion capabilities would greatly enhance their adaptability in dynamic environments. Inspired by organisms capable of rolling locomotion, this paper presents a lightweight shape morphable rolling robot which integrates an origami skeleton with muscle-like pneumatic pouches as drivers and electroadhesion (EA) pads as anchors. The origami skeleton of the robot is a hexag-onal loop structure composed of polyethylene terephthalate (PET) panels with flexural hinges between them. Pneumatic pouch actuators are embedded between the panels to change the configuration of the skeleton. The flat panels of the origami skeleton house electroadhesion actuators which can adhere to different surfaces with different slopes and materials. Two sequential control schemes are proposed that enable the robot to move forward and backward accurately by controlling the air pressure in the pouches and voltage supplied to the EA pads. Using combined actuation of pneumatic pouches and EA pads, the robot is able to roll on both horizontal and inclined surfaces as well as transit from horizontal to fully vertical surfaces. The robot shows less than 1% error in positioning after one complete forward and backward rolling cycle. Owing to its use of thin sheet materials for skeleton and pouch actuators and EA pads, the robot is lightweight weighing only 25 g. These unique properties of the robot will enable the deployment of such versatile mobile robots to conduct tasks remotely in challenging environments
A soft jellyfish robot driven by a dielectric elastomer actuator
No full textAlthough dielectric elastomers have been extensively studied recently, to date there has been little research into application of dielectric elastomer actuators to undersea robots. This letter focuses on development of a jellyfish robot using a dielectric elastomer actuator, which exhibits muscle-like properties including large deformation and high energy density. We carry out experiments to test the actuator’s deformation and force. Theoretical simulations are conducted to analyze the performance of the actuator, which are qualitatively consistent with the experiments. The preliminary studies show that this jellyfish robot based on dielectric elastomer technology can move effectively in water. The robot also exhibits fast response and high capacity of payload (compared to its self-weight)
High resolution, large area vision-based tactile sensing based on a novel piezoluminescent skin
No full textThe ability to precisely perceive external physical interactions would enable robots to interact effectively with the environment and humans. While vision-based tactile sensing has improved robotic grippers, it is challenging to realize high resolution vision-based tactile sensing in robot arms due to presence of curved surfaces, difficulty in uniform illumination, and large distance of sensing area from the cameras. In this article, we propose a novel piezoluminescent skin that transduces external applied pressures into changes in light intensity on the other side for viewing by a camera for pressure estimation. By engineering elastomer layers with specific optical properties and integrating a flexible electroluminescent panel as a light source, we develop a compact tactile sensing layer that resolves the layout issues in curved surfaces. We achieved multipoint pressure estimation over an expansive area of 502 cm
2 with high spatial resolution, a two-point discrimination distance of 3 mm horizontally and 5 mm vertically which is comparable to that of human fingers as well as a high localization accuracy (RMSE of 1.92 mm). These promising attributes make this tactile sensing technique suitable for use in robot arms and other applications requiring high resolution tactile information over a large area.</p
Soft robots based on dielectric elastomer actuators: a review
No full textConventional robots are mainly made of rigid materials, such as steel and aluminum. Recently there has been a surge in the popularity of soft robots owing to their inherent compliance, strong adaptability and capability to work effectively in unstructured environments. Of the multitude of soft actuation technologies, dielectric elastomer actuators (DEAs), also nicknamed 'artificial muscles', exhibit fast response, large deformation and high energy density, and can simply be actuated with electric voltage. In this paper, we will discuss applications of DEAs to soft robots, including robotic grippers, terrestrial robots, underwater robots, aerial robots and humanoid robots. We will survey the state of the art regarding these interesting applications and outline the challenges and perspectives. As we know, there have been extensive studies on dielectric elastomer technology in the aspects of materials, mechanics, design, fabrication and controls. To enable practical applications, efforts are underway to decrease operational voltages, improve reliability, and impart new functionalities. Key challenges include the development of freestanding actuators, untethered operation, smart/electronics free actuators, solid and stretchable electrodes, miniaturization, combination of synergistic actuation technologies to impart novel functionalities, development of effective control strategies, etc. We hope that this review can facilitate and enhance applications of dielectric elastomer technology to soft robots
Bioinspired soft actuators for eyeball motions in humanoid robots
No full textTechnological progress in advanced materials and artificial intelligence has given an impetus to the development of humanoid robots that can mimic human appearance and interact with people effectively. Eyeball motions play a key role in facial expression of humanoid robots, and can greatly improve the relationship between the robots and the users. In this paper, we develop soft actuators which can achieve horizontal, vertical, and circular motions, for the application of robotic eyeballs. Inspired by nature, this soft actuator combines three linear dielectric elastomer actuators (DEAs). By controlling voltages applied to the three DEAs, this soft actuator is capable of realizing the horizontal, vertical, and circular motions. Each DEA is developed with optimal designs to achieve large voltage-induced deformation. The calculations on the optimal prestretches of the DEA are qualitatively consistent with the experiments. By combining two DEAs together, the soft actuator can mimic the horizontal motion of human eyeballs. By combing three DEAs together, the soft actuator can track desired motion trajectories effectively. This project can contribute to the development of humanoid robots with bioinspired design, lightweight, and low cost. The humanoid robot based on soft actuators can also improve the interaction with the users, due to its natural appearance, excellent safety and adaptability, and quiet operation
Silicone based capacitive E-Skin sensor for soft surgical robots
No full textIn this extended abstract, we present a soft stretchable multi-modal capacitive skin sensor that can be used for exteroception and proprioception in soft surgical manipulators. A soft skin prototype was made using Ecoflex, embedding three conductive carbon grease terminal layers. This soft skin is capable of measuring stretch and touch simultaneously. The soft skin measures uniaxial stretches from 1 to 1.2475 within an error range of 2.6% and can also quantify as well as localize local indentation. An algorithm is developed that decouples local change, i.e., due to indentation, from global strain, due to stretch. An experimental study was conducted; results are presented
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