scholarly journals Motion of a Legged Bidirectional Miniature Piezoelectric Robot Based on Traveling Wave Generation

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 321 ◽  
Author(s):  
Jorge Hernando-García ◽  
Jose Luis García-Caraballo ◽  
Víctor Ruiz-Díez ◽  
Jose Luis Sánchez-Rojas
Keyword(s):  
Traveling Wave ◽  
Glass Plate ◽  
Wave Generation ◽  
Design Guidelines ◽  
1D Model ◽  
3D Printed ◽  
Autonomous Version ◽  
Communication Control ◽  
Miniature Robot ◽  
Patch Length

This article reports on the locomotion performance of a miniature robot that features 3D-printed rigid legs driven by linear traveling waves (TWs). The robot structure was a millimeter-sized rectangular glass plate with two piezoelectric patches attached, which allowed for traveling wave generation at a frequency between the resonant frequencies of two contiguous flexural modes. As a first goal, the location and size of the piezoelectric patches were calculated to maximize the structural displacement while preserving a standing wave ratio close to 1 (cancellation of wave reflections from the boundaries). The design guidelines were supported by an analytical 1D model of the structure and could be related to the second derivative of the modal shapes without the need to rely on more complex numerical simulations. Additionally, legs were bonded to the glass plate to facilitate the locomotion of the structure; these were fabricated using 3D stereolithography printing, with a range of lengths from 0.5 mm to 1.5 mm. The optimal location of the legs was deduced from the profile of the traveling wave envelope. As a result of integrating both the optimal patch length and the legs, the speed of the robot reached as high as 100 mm/s, equivalent to 5 body lengths per second (BL/s), at a voltage of 65 Vpp and a frequency of 168 kHz. The blocking force was also measured and results showed the expected increase with the mass loading. Furthermore, the robot could carry a load that was 40 times its weight, opening the potential for an autonomous version with power and circuits on board for communication, control, sensing, or other applications.

scholarly journals Engineering Design Process of Face Masks Based on Circularity and Life Cycle Assessment in the Constraint of the COVID-19 Pandemic

2021 ◽  
Vol 13 (9) ◽  
pp. 4948
Author(s):  
Núria Boix Rodríguez ◽  
Giovanni Formentini ◽  
Claudio Favi ◽  
Marco Marconi
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Environmental Sustainability ◽  
Design Guidelines ◽  
New Device ◽  
Engineering Design Process ◽  
Life Cycle Perspective ◽  
Different Types ◽  
3D Printed ◽  
Negative Impacts

Face masks are currently considered key equipment to protect people against the COVID-19 pandemic. The demand for such devices is considerable, as is the amount of plastic waste generated after their use (approximately 1.6 million tons/day since the outbreak). Even if the sanitary emergency must have the maximum priority, environmental concerns require investigation to find possible mitigation solutions. The aim of this work is to develop an eco-design actions guide that supports the design of dedicated masks, in a manner to reduce the negative impacts of these devices on the environment during the pandemic period. Toward this aim, an environmental assessment based on life cycle assessment and circularity assessment (material circularity indicator) of different types of masks have been carried out on (i) a 3D-printed mask with changeable filters, (ii) a surgical mask, (iii) an FFP2 mask with valve, (iv) an FFP2 mask without valve, and (v) a washable mask. Results highlight how reusable masks (i.e., 3D-printed masks and washable masks) are the most sustainable from a life cycle perspective, drastically reducing the environmental impacts in all categories. The outcomes of the analysis provide a framework to derive a set of eco-design guidelines which have been used to design a new device that couples protection requirements against the virus and environmental sustainability.

A shape memory alloy–actuated soft crawling robot based on adaptive differential friction and enhanced antagonistic configuration

2020 ◽  
Vol 31 (16) ◽  
pp. 1920-1934 ◽  
Author(s):  
Chen Liang ◽  
Yongquan Wang ◽  
Tao Yao ◽  
Botao Zhu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stride Length ◽  
Parametric Design ◽  
Thermoplastic Polyurethane ◽  
Interaction Mechanism ◽  
Experimental Tests ◽  
The Body ◽  
3D Printed ◽  
Miniature Robot

This article presents a soft crawling robot prototype with a simple architecture inspired by inchworms. The robot functionally integrates the torso (body) and feet in a monolithic curved structure that only needs a single shape memory alloy coil and differential friction to actuate it. A novel foot configuration is proposed, which makes the two feet, with an anti-symmetrical friction layout, can be alternately anchored, to match the contraction–recovery sequence of the body adaptively. Based on the antagonistic configuration between the shape memory alloy actuator and the elastic body, a vertically auxiliary spring was adopted to enhance the interaction mechanism. Force and kinematic analysis was undertaken, focusing on the parametric design of the special foot configuration. A miniature robot prototype was then 3D-printed (54 mm in length and 9.77 g in weight), using tailored thermoplastic polyurethane elastomer as the body material. A series of experimental tests and evaluations were carried out to assess its performance under different conditions. The results demonstrated that under appropriate actuation conditions, the compact robot prototype could accomplish a relative speed of 0.024 BL/s (with a stride length equivalent to 27% of its body length) and bear a load over five times to its own weight.

Materials Testing of 3D Printed ABS and PLA Samples to Guide Mechanical Design

2016 ◽  
Author(s):  
Daniel Farbman ◽  
Chris McCoy
Keyword(s):  
Finite Element Analysis ◽  
Tensile Testing ◽  
Mechanical Design ◽  
Tensile Tests ◽  
Design Guidelines ◽  
Materials Testing ◽  
Element Analysis ◽  
Dog Bone ◽  
3D Printed ◽  
Future Work

A set of monotonic tensile tests was performed on 3-D printed plastics following ASTM standards. The experiment tested a total of 13 “dog bone” test specimens where the material, infill percentage, infill geometry, load orientation, and strain rate were varied. Strength-to-weight ratios of the various infill geometries were compared. It was found through tensile testing that the specific ultimate tensile strength (MPa/g) decreases as the infill percentage decreases and that hexagonal pattern infill geometry was stronger and stiffer than rectilinear infill. However, in finite element analysis, rectilinear infill showed less deformation than hexagonal infill when the same load was applied. Some design guidelines and future work are presented.

scholarly journals Comparative Study of Traveling and Standing Wave-Based Locomotion of Legged Bidirectional Miniature Piezoelectric Robots

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 171
Author(s):  
Jorge Hernando-García ◽  
Jose Luis García-Caraballo ◽  
Víctor Ruiz-Díez ◽  
Jose Luis Sánchez-Rojas
Keyword(s):  
Traveling Waves ◽  
Vibration Mode ◽  
Glass Plate ◽  
Excitation Frequency ◽  
Standing Waves ◽  
Flexural Vibration ◽  
Precise Location ◽  
Modes Of Vibration ◽  
3D Printed ◽  
Locomotion Speed

The use of wave-based locomotion mechanisms is already well established in the field of robotics, using either standing waves (SW) or traveling waves (TW). The motivation of this work was to compare both the SW- and the TW-based motion of a 20-mm long sub-gram glass plate, with attached 3D printed legs, and piezoelectric patches for the actuation. The fabrication of the robot did not require sophisticated techniques and the speed of motion was measured under different loading conditions. In the case of the TW mechanism, the influence of using different pairs of modes to generate the TW on the locomotion speed has been studied, as well as the effect of the coupling of the TW motion and the first flexural vibration mode of the legs. This analysis resulted in a maximum unloaded speed of 6 bodylengths/s (BL/s) at 65 V peak-to-peak (Vpp). The SW approach also examined different modes of vibration and a speed of locomotion as high as 14 BL/s was achieved, requiring, unlike the TW case, a highly precise location of the legs on the glass supporting platform and a precise tuning of the excitation frequency.

scholarly journals Linear Motors Based on Piezoelectric MEMS

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 9
Author(s):  
Víctor Ruiz-Díez ◽  
Jorge Hernando-García ◽  
José Luis Sánchez-Rojas
Keyword(s):  
Wave Generation ◽  
Aluminium Nitride ◽  
Piezoelectric Film ◽  
Vibrational Modes ◽  
Electromechanical Systems ◽  
Linear Motors ◽  
3D Printed ◽  
Piezoelectric Mems ◽  
And Performance ◽  
Hybrid Devices

This paper reports the design, fabrication and performance of Micro-electromechanical Systems (MEMS) piezoelectric bidirectional conveyors featuring 3D-printed legs in bridge resonators. The structures consisted of aluminium-nitride (AlN) piezoelectric film on top of millimetre-sized rectangular thin silicon bridges and two electrode patches. The position and size of the patches were analytically optimised for wave generation, while the addition of 3D-printed legs, for a controlled contact, allowed for a further step into the manufacturing of efficient linear motors. Such hybrid devices have recently demonstrated the conveyance of sliders—surpassing several times the motor weight—with speeds of 1.7 mm/s while operated at 6 V and 19.3 kHz. However, by the optimisation of various aspects of the device such as the vibrational modes and excitation signals, speeds above 25 mm/s were demonstrated.

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