A Lobster-Inspired Hybrid Actuator With Rigid and Soft Components (original) (raw)
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A reconfigurable hybrid actuator with rigid and soft components
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017
Classical rigid-bodied robotic systems are presented with proven success in theoretical development and industrial applications, are recently challenged by the emergence of soft robotics due to a growing need in physical human-robot interactions (pHRI), such as wearable devices, medical robots, personal robots, etc. In this paper, we present the design and fabrication of a robust, hybrid bending actuator build from both rigid and soft components inspired by crustaceans, where its bending radius and axis can be mechanically programmed through the selective activation of the rigid exterior joints, actuated by the soft actuators inside. The hybrid actuator was experimentally measured in terms of bending and force tests to demonstrate the utility of this design. Finally, a case study was presented to demonstrate its capacity to adapt to specific objects geometry, anticipating its potential application in situations where compliance is the priority.
Hybrid Soft Robots Incorporating Soft and Stiff Elements
arXiv (Cornell University), 2022
Soft robots are inherently compliant and have a strong potential to realize human-friendly and safe robots. Despite continued research highlighting the potential of soft robots, they remain largely confined to laboratory settings. In this work, inspired by spider monkeys' tails, we propose a hybrid soft robot (HSR) design. We detail the design objectives and methodology to improve controllable stiffness range and achieve independent stiffness and shape control. We extend the curve parametric approach to We experimentally demonstrate that the proposed HSR has about 100% stiffness range increase than a previous soft robot design with identical physical dimensions. In addition, we empirically map HSR's bending shape-pressure-stiffness and present an application examplea soft robotic gripper-to demonstrate the decoupled nature of stiffness and shape variations. Experimental results show that proposed HSR can be successfully used in applications where independent stiffness and shape control is desired.
Robotics
Several bio-inspired underwater robots have been demonstrated in the last few years that can horizontally swim using different smart actuators. However, very few works have been presented on robots which can swim vertically, have a payload and resemble a jellyfish-like creature. In this work, we present the design, fabrication, and performance characterization of a new tethered robotic jellyfish, which is based on inflatable soft pneumatic composite (SPC) actuators. These soft actuators use compressed air to expand and contract, which help the robot to swim vertically in water. The soft actuators consist of elastomeric air chambers and very thin steel springs, which contribute to gaining faster motion of the biomimetic robot. A prototype of 220 mm in diameter and consisting of eight actuating units was fabricated and tested underwater in a fish tank. It reached a height of 400 mm within 2.5 s while carrying a dead weight of 100 g when tested at 70 psi (483 kPa) pressure. This high p...
A lobster-inspired robotic glove for hand rehabilitation
2017 IEEE International Conference on Robotics and Automation (ICRA), 2017
This paper presents preliminary results of the design, development, and evaluation of a hand rehabilitation glove fabricated using lobster-inspired hybrid design with rigid and soft components for actuation. Inspired by the bending abdomen of lobsters, hybrid actuators are built with serially jointed rigid shells actuated by pressurized soft chambers inside to generate bending motions. Such bio-inspiration absorbs features from the classical rigid-bodied robotics with preciselydefined motion generation, as well as the emerging soft robotics with lightweight , physically safe, and adaptive actuation. The fabrication procedure is described, followed by experiments to mechanically characterize these actuators. Finally, an openpalm glove design integrated with these hybrid actuators are presented for a qualitative case study. A hand rehabilitation system is developed by learning patterns of the sEMG signals from the users forearm to train the assistive glove for hand rehabilitation exercises.
Design and Development of a Soft Actuator for a Robot Inspired by the Octopus Arm
2008
The octopus provides roboticists with a good example of a completely compliant structure that can however reach good levels of stiffness and then exert forces on its environment. With no rigid structures, the octopus can deform its body and fit small apertures, its arms can bend in all directions and they can even elongate. The peculiar muscular structure of the octopus arm, named muscular hydrostat, acts in fact as a modifiable skeleton, providing stiffness when and where needed. A key point in imitating this muscular structure is that the muscular hydrostat creates a sort of antagonistic mechanism between different muscle fibres. As a consequence, the arm movements are given by a combination of contractions of part of the muscles and passive stretching of the other muscles. On one side, this reduces the contraction requirements for the single muscle; on the other side, the contractile structure must be compliant and passively stretchable. The contractile units proposed here are built with EAP (Electro-Active Polymer) technology, with a particular geometry that increases the contraction range and force, by using soft materials. Contraction tests on prototypes of the contracting units show a very good similarity with a theoretical model and support the starting hypothesis on the possibility of building a robotic octopus-like arm based on an artificial muscular hydrostat.
Soft Actuators and Robots that Are Resistant to Mechanical Damage
Advanced Functional Materials, 2013
This paper characterizes the ability of soft pneumatic actuators and robots to resist mechanical insults that would irreversibly damage or destroy hard robotic systems—systems fabricated in metals and structural polymers, and actuated mechanically—of comparable sizes. The pneumatic networks that actuate these soft machines are formed by bonding two layers of elastomeric or polymeric materials that have different moduli on application of strain by pneumatic infl ation; this difference in strain between an extensible top layer and an inextensible, strain-limiting, bottom layer causes the pneumatic network to expand anisotropically. While all the soft machines described here are, to some extent, more resistant to damage by compressive forces, blunt impacts, and severe bending than most corresponding hard systems, the composition of the strain-limiting layers confers on them very different tensile and compressive strengths.
A Resilient, Untethered Soft Robot
Soft Robotics, 2014
A pneumatically powered, fully untethered mobile soft robot is described. Composites consisting of silicone elastomer, polyaramid fabric, and hollow glass microspheres were used to fabricate a sufficiently large soft robot to carry the miniature air compressors, battery, valves, and controller needed for autonomous operation. Fabrication techniques were developed to mold a 0.65-meter-long soft body with modified Pneu-Net actuators capable of operating at the elevated pressures (up to 138 kPa) required to actuate the legs of the robot and hold payloads of up to 8 kg. The soft robot is safe to interact with during operation, and its silicone body is innately resilient to a variety of adverse environmental conditions including snow, puddles of water, direct (albeit limited) exposure to flames, and the crushing force of being run over by an automobile.
Soft Robotics: New Perspectives for Robot Bodyware and Control
Frontiers in bioengineering and biotechnology, 2014
The remarkable advances of robotics in the last 50 years, which represent an incredible wealth of knowledge, are based on the fundamental assumption that robots are chains of rigid links. The use of soft materials in robotics, driven not only by new scientific paradigms (biomimetics, morphological computation, and others), but also by many applications (biomedical, service, rescue robots, and many more), is going to overcome these basic assumptions and makes the well-known theories and techniques poorly applicable, opening new perspectives for robot design and control. The current examples of soft robots represent a variety of solutions for actuation and control. Though very first steps, they have the potential for a radical technological change. Soft robotics is not just a new direction of technological development, but a novel approach to robotics, unhinging its fundamentals, with the potential to produce a new generation of robots, in the support of humans in our natural environm...
Design and Analysis of a Soft Pneumatic Actuator with Origami Shell Reinforcement
Soft Robotics, 2016
Soft pneumatic actuators (SPAs) are versatile robotic components enabling diverse and complex soft robot hardware design. However, due to inherent material characteristics exhibited by their primary constitutive material, silicone rubber, they often lack robustness and repeatability in performance. In this article, we present a novel SPA-based bending module design with shell reinforcement. The bidirectional soft actuator presented here is enveloped in a Yoshimura patterned origami shell, which acts as an additional protection layer covering the SPA while providing specific bending resilience throughout the actuator's range of motion. Mechanical tests are performed to characterize several shell folding patterns and their effect on the actuator performance. Details on design decisions and experimental results using the SPA with origami shell modules and performance analysis are presented; the performance of the bending module is significantly enhanced when reinforcement is provided by the shell. With the aid of the shell, the bending module is capable of sustaining higher inflation pressures, delivering larger blocked torques, and generating the targeted motion trajectory.
The Quest for Natural Machine Motion: An Open Platform to Fast-Prototyping Articulated Soft Robots
IEEE Robotics & Automation Magazine, 2017
oft robots are one of the most significant recent evolutions in robotics. They rely on compliant physical structures purposefully designed to embody desired characteristics. Since their introduction, they have shown remarkable applicability in overcoming their rigid counterparts in such areas as interaction with humans, adaptability, energy efficiency, and maximization of peak performance. Nonetheless, we believe that research on novel soft robot applications is still slowed by the difficulty in obtaining or developing a working soft robot structure to explore novel applications. In this article, we present the Natural Machine Motion Initiative (NMMI), a modular open platform that aims to provide the scientific community with tools for fast and easy prototyping of articulated soft robots. Such a platform is composed of three main open hardware modules: the Qbmoves variable-stiffness actuators (VSAs) to build the main robotic structure, soft end effectors (EEs) to interact with the world, and a pool of application-specific add-ons. We also discuss many novel uses of the platform to rapidly prototype (RP) and test new robotic structures with original soft capabilities, and we propose NMMIbased experiments. Many New Robotics Possibilities Enabling a true integration of robots in human-populated environments is one of the most ambitious long-term goals of robotics research. Robot evolution in terms of safety, intelligence, affordability, and social skills has been impressive in the past decade and has brought several robotic devices to market. However, making robots able to safely interact with the public is hindered by the fact that classical industrial robots, as stiff and heavy machines, can generate dangerous and unstable interactions in uncertain environments. To overcome this limitation, and inspired by biological actuation, so-called soft robotics was born [1], i.e., robot development that embeds elastic elements with either fixed or variable mechanical compliance. The first goal for soft robots ©istockphoto.com/brendan hunter