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anNiTi-Pt wire with an unexcited length that is smaller than the distance between the
slots of the horns and the anchor block; namely, 9.8mmat 25 C instead of 9.88mm.
For the robot used in the locomotion experiments, the measured spring stiffness is
4.26N/mm (See Section 4.3.5) with a corresponding loading stress of 168MPa.
Note that the proposed robotic design allows us to arbitrarily set the loading stress
acting on the NiTi-Pt wire by adjusting the location of the crimp-clamps. Similarly,
the entire artificial muscle can be easily replaced if different geometrical or catalytic
characteristics for effective operation are required.
iv. The last category is composed of the bioinspired microrobotic legs with claws that
are capable of inducing anisotropic friction, thus emulating the friction mechanism
employed by beetles of the subspecies Pachnoda marginata peregrina (109). As seen
in Fig. 4.5, C and H, the two forelegs are installed at the distal end of the transmission
and the two hindlegs at the bottom of the tank, employing tab-and-slot features.
The overall design and limb configuration enable RoBeetle prototypes to locomote
unidirectionally using the simple proposed two-anchor crawl gait, which is similar
to the scheme observed in some types of inchworms; for example, the patterns of
caterpillars of the speciesManduca sexta (110), which conceptually also resemble
the locomotion method employed by the soft robot in (111). All the fundamental
parameters of the RoBeetle prototype employed in the experiments are summarized
in Table S3.
4.3.2 Fabrication of the robotic prototypes
With the exception of the artificial muscles, all the mechanisms and structural compo-nents
of the RoBeetle prototypes are designed and fabricated using the SCM method,
especially some of the techniques described in (112). In specific, the fuel tank, lid,
79
Object Description
| Title | Development of biologically-inspired sub-gram insect-scale autonomous robots |
| Author | Yang, Xiufeng |
| Author email | xiufeng@usc.edu;showind4@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Mechanical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2020-01-14 |
| Date submitted | 2020-05-11 |
| Date approved | 2020-05-12 |
| Restricted until | 2020-05-12 |
| Date published | 2020-05-12 |
| Advisor (committee chair) | Pérez-Arancibia, Néstor Osvaldo |
| Advisor (committee member) |
Ronney, Paul David Chen, Yong |
| Abstract | Researches working on the development of mobile robots at the sub-gram millimeter scale are mostly inspired by insects surrounding us and motivated by a significant number of potential applications. Despite impressive progress in the past two decades, state-of-the-art microrobots are yet to achieve the same levels of autonomy, agility, and intelligence exhibited by their natural counterparts while completing tasks. The most fundamental difficulties lie on stringent constraints on the number of actuators, and the power and control dependences on external sources. ❧ To overcome these non-trivial challenges, in this work, we explored the fundamental and practical aspects of two micro-actuation methods, namely piezoelectric ceramics and shape-memory-alloys (SMAs). We developed two different microrobots based on them. The first insect-sized robot is a 95-mg four-winged flying robot, Bee⁺, driven by two pairs of twinned unimorph piezoelectric actuators. The second one, named RoBeetle, is an 88-mg autonomous crawling robot actuated by catalyst-coated SMA composite artificial muscles. ❧ The work in this dissertation makes the following contributions. Firstly, Bee⁺, as a significant upgrade of current flying robotic insects, is the lightest and smallest four-winged robot created to date. Its two pairs of twinned unimorph actuators enable us to increase the independent actuation units without substantially increasing the weight and the size of the robot. Compared to state-of-the-art bimorph actuators, the twinned unimorph configuration also reduces the complexity of fabrication and statistical frequency of microscopic assembly error. ❧ Secondly, we developed a radical new actuator for microrobotic applications, which is the catalytic composite artificial muscle made of nickel-titanium-alloy (Nitinol) and platinum (Pt) black. This actuator inherently possesses the high-work-density of Nitinol and can convert the chemical energy from high-energy-density (HED) fuels into applicable mechanical outputs through flameless catalytic combustion. We achieved fast controlled actuation (1 Hz) on this artificial muscle by implementing a logic-based control algorithm on a custom-made in-house thermomechanical experimental platform. ❧ Last and foremost, we developed RoBeetle, an 88-mg robot actuated by a catalytic artificial muscle, which is the first sub-gram autonomous robot created to date. An essential innovation that makes the autonomous-operation of RoBeetles possible is a feedback control scheme of the catalytic combustion process at the millimeter-scale. This on-board mechanical control mechanism indirectly utilizes as feedback the reaction temperature on the surface of the artificial muscle. Specifically, the mechanism employs the periodical actuation output according to an identified hysteric mapping, to modulate the flow of the fuel through synchronously adjusting the openings of micro-valves. The design of this bio-inspired microrobot powered by HED fuel could serve as a paradigm for the creation of a new diverse generation of autonomous robotic insects in terrestrial, aquatic, and aerial environments. |
| Keyword | microrobotics; flapping-wing micro aerial vehicle; actuator; artificial muscle; flight control; catalytic combustion; shape-memory alloys; platinum coating; energy density; mechanism; locomotion; biologically-inspired; robotic insects; sub-gram; microfabrication; piezoelectric; unimorph; microelectromechanical systems |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Contributing entity | University of Southern California |
| Rights | Yang, Xiufeng |
| Physical access | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-YangXiufen-8491.pdf |
| Archival file | Volume12/etd-YangXiufen-8491.pdf |
Description
| Title | Page 92 |
| Full text | anNiTi-Pt wire with an unexcited length that is smaller than the distance between the slots of the horns and the anchor block; namely, 9.8mmat 25 C instead of 9.88mm. For the robot used in the locomotion experiments, the measured spring stiffness is 4.26N/mm (See Section 4.3.5) with a corresponding loading stress of 168MPa. Note that the proposed robotic design allows us to arbitrarily set the loading stress acting on the NiTi-Pt wire by adjusting the location of the crimp-clamps. Similarly, the entire artificial muscle can be easily replaced if different geometrical or catalytic characteristics for effective operation are required. iv. The last category is composed of the bioinspired microrobotic legs with claws that are capable of inducing anisotropic friction, thus emulating the friction mechanism employed by beetles of the subspecies Pachnoda marginata peregrina (109). As seen in Fig. 4.5, C and H, the two forelegs are installed at the distal end of the transmission and the two hindlegs at the bottom of the tank, employing tab-and-slot features. The overall design and limb configuration enable RoBeetle prototypes to locomote unidirectionally using the simple proposed two-anchor crawl gait, which is similar to the scheme observed in some types of inchworms; for example, the patterns of caterpillars of the speciesManduca sexta (110), which conceptually also resemble the locomotion method employed by the soft robot in (111). All the fundamental parameters of the RoBeetle prototype employed in the experiments are summarized in Table S3. 4.3.2 Fabrication of the robotic prototypes With the exception of the artificial muscles, all the mechanisms and structural compo-nents of the RoBeetle prototypes are designed and fabricated using the SCM method, especially some of the techniques described in (112). In specific, the fuel tank, lid, 79 |
