A Bioinspired Soft Actuated Material (original) (raw)
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Design and Characterisation of a Muscle-Mimetic Dielectrophoretic Ratcheting Actuator
IEEE Robotics and Automation Letters
The high potential impact of soft robotics is hampered by a lack of actuators that combine high-force, high-work and high-power capabilities, limiting application in real-world problems. Typically, soft actuators are tuned to an application by gearing-for example, trading power for strain. An example of a recently developed soft-actuator which exploits such gearing is the dielectrophoretic liquid zipping (DLZ) actuator. DLZs can produce large strains (> 99%) and power densities comparable to biological muscles, but cannot achieve both in a single actuator. In this work, we introduce a muscle-mimetic DLZ ratcheting actuator (DLZ-R) that allows multiple DLZ-R heads to operate in parallel, thereby increasing force output without sacrificing stroke or power. We first characterise the effect of geometry on the performance of a 1-head DLZ-R, before demonstrating that the force, work, and power output of the DLZ-R scale linearly with the number of active DLZ heads. Next, we investigate the relationship between driving frequency and power output. Finally, we demonstrate a 12-head DLZ ratchet. We believe the DLZ-R represents a step towards soft actuators that can provide both high-work and high-power and the widespread use of soft technologies.
Chapter 6 Rapid prototyping of soft bioactuators
2018
The driving principle behind man-made robots is force actuation leading to a form of directed movement or locomotion. Natural systems can motivate the design and development of robots that replicate or enhance many basic locomotive strategies—such as climbing, crawling,1 walking,2 jumping,3,4 or swimming5–9— with novel solutions. Biological soft robotics derives inspiration and design principles from organic systems to facilitate engineering approaches to challenges that have historically plagued conventional robotic actuators. Traditional hard skeletons (made of high stiffness metals or plastics) and electromagnetic actuators can
Mechatronics, 2000
Actuators, the prime drive unit in any system (biological or mechanical), are responsible for transferring energy in its many forms into mechanical motion that permits interaction with the external environment. The complexity of the organic mechanism has traditionally precluded its emulation, but a demand in robotic and other mechatronic systems for closer human interaction involving safety, redundancy, self-repair and anity, has highlighted the potential bene®ts of softness, both in terms of functional and physical behaviour. This is prompting a shift in the traditional design paradigm based on motors±gears±bearings±links to a novel biomimetic schema based on muscle±tendon±joint±bone. Among the most fundamental features of actuators designed around this format will be a desire to emulate the performance of natural muscle in forming a safe and natural interaction medium, while still possessing the bene®cial attributes of conventional engineering actuators, i.e. high power to weight/volume, high force weight/volume and good positional and force control. In this paper a study has been undertaken of two novel forms of actuators (polymeric and pneumatic Muscle), that have characteristics that can be broadly classi®ed as giving them a range of bio-mimetic functions.
Mechanical Programming of Soft Actuators by Varying Fiber Angle
Soft Robotics, 2015
In this work we investigate the influence of fiber angle on the deformation of fiber-reinforced soft fluidic actuators. We demonstrate that, by simply varying the fiber angle, we can tune the actuators to achieve a wide range of motions, including axial extension, radial expansion, and twisting. We investigate the relationship between fiber angle and actuator deformation by performing finite element simulations for actuators with a range of different fiber angles, and we verify the simulation results by experimentally characterizing the actuators. By combining actuator segments in series, we can achieve combinations of motions tailored to specific tasks. We demonstrate this by using the results of simulations of separate actuators to design a segmented wormlike soft robot capable of propelling itself through a tube and performing an orientation-specific peg insertion task at the end of the tube. Understanding the relationship between fiber angle and motion of these soft fluidic actuators enables rapid exploration of the design space, opening the door to the iteration of exciting soft robot concepts such as flexible and compliant endoscopes, pipe inspection devices, and assembly line robots.
Toward motor-unit-recruitment actuators for soft robotics
5th IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics, 2014
Among the many features of muscles, their softness, (the ability to deform to accommodate uncertainty in the environment), and their ability to continue functioning despite disturbances, even partial damage, are qualities one would desire to see in robotic actuators. These properties are intimately related to the manner in which muscles work since they arise from the progressive recruitment of many motor units. This differs greatly from current robotic actuator technologies. We present an actuation platform prototype that can support experimental validation of algorithms for muscle fiber recruitment-inspired control, and where further ways to exploit discretization and redundancy in muscle-like control can be discovered. This platform, like muscles, is composed of discretely activated motor units with an integrated compliant coupling. The modular, cellular structure endows the actuator with good resilience in response to damage. It can also be repaired or modified to accommodate changing requirements in situ rather than replaced. Several performance metrics particular to muscle-like actuators are introduced and calculated for one of these units. The prototype has a blocked force of 2.51 N, a strain rate of 21.1 %, and has an input density of 5.46 ×10 3 motor units per square meter. It consumes 18 W of electrical power during a full isometric contraction. The actuator unit is 41.0 mm 3 in size. The force during isometric contractions as it varies with activation is evaluated experimentally for two configurations of modules.