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arXiv 2023年

作者： Tosun, Berk Samur, Evren Graduate Program in Systems and Control Engineering Bogazici University Istanbul Turkey Department of Mechanical Engineering Bogazici University Istanbul Turkey

Safety concerns during the operation of legged robots must be addressed to enable their widespread use. Machine learning-based control methods that use model-based constraints provide promising means to improve robot safety. This study presents a modular safety filter to improve the safety of a legged robot, i.e., reduce the chance of a fall. The prerequisite is the availability of a robot that is capable of locomotion, i.e., a nominal controller exists. During locomotion, terrain properties around the robot are estimated through machine learning which uses a minimal set of proprioceptive signals. A novel deep-learning model utilizing an efficient transformer architecture is used for the terrain estimation. A quadratic program combines the terrain estimations with inverse dynamics and a novel exponential control barrier function constraint to filter and certify nominal control signals. The result is an optimal controller that acts as a filter. The filtered control signal allows safe locomotion of the robot. The resulting approach is generalizable, and could be transferred with low effort to any other legged system. Copyright © 2023, The Authors. All rights reserved.

关键词： Robots

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Enhancement and Optimization of the Propulsion System Modules of Unmanned Aerial Vehicles

Enhancement and Optimization of the Propulsion System Module...

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2024 Asia Conference on Electronic Technology, ACET 2024

作者： Shiau, Y.R. Fang, J. Huang, Y.C. Department of Industrial Engineering and Systems Management Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung Taiwan Department of Aerospace and Systems Engineering Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung Taiwan Ph.D. Program of Mechanical and Aeronautical Engineering Feng Chia University No. 100 Wenhwa Rd. Seatwen Taichung Taiwan

ISBN: (纸本)9781510681361

Unmanned aerial vehicles (UAVs) are widely used in various industries. The present study focused on the optimization of the configuration of the vertical electric ducted fans (EDFs) of UAVs to enhance the vertical takeoff and landing (VTOL) performance of UAVs, improve the configuration of their propulsion system, address the potential risk of exposed propellers, and reduce the space required between the fluid channel and the outlet in horizontal EDFs. A UAV aircraft module with a vertical EDF configuration was designed, following which structural analysis and flow field analysis were conducted using Ansys. The results of these analyses indicate that the overall flow of the designed module is smooth and stable without vortex generation and that the inlet and outlet air velocity performance of this module is excellent. The lift parameters of the rotor groups of the designed module are identical to each other;thus, the flight stability of the UAV in the air can be maintained, and the requirements for optimized design can be met. This study makes two contributions to the literature. First, the structural module of a vertical EDF propulsion system was proposed with an encapsulated impeller set hidden inside the vehicle structure to reduce the risk of propeller exposure. Second, the configuration of vertical EDF compared to the horizontal configuration shortens the airflow channel, which helps to stabilize the wind speed at the outlet, thereby increasing lifting capacity and propulsion efficiency. © 2024 SPIE.

关键词： Propellers

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Hardware particle swarm optimization based on the attractive-repulsive scheme for embedded applications

Hardware particle swarm optimization based on the attractive...

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2010 International Conference on Reconfigurable Computing and FPGAs, ReConFig 2010

作者： Muñoz, Daniel M. Llanos, Carlos H. Dos S. Coelho, Leandro Ayala-Rincón, Mauricio Department of Mechanical Engineering Automation and Control Group/GRACO University of Brasilia Brasilia DF Brazil Industrial and Systems Engineering Graduate Program LAS/PPGPES Pontifical Catholic University of Parana Curitiba Parana Brazil Department of Computer Science and Mathematics University of Brasilia Brasilia DF Brazil

ISBN: (纸本)9780769543147

Particle Swarm Optimization (PSO) algorithms have been proposed to solve engineering problems that require to find an optimal point of operation. However, the PSO algorithm suffers from premature convergence and high elapsed time when solving multimodal and large scale engineering problems. This problem becomes an evident drawback for embedded applications in which the microcontrollers often operates at low computational capacity. This paper proposes a hardware implementation of a parallel self-adaptive PSO algorithm based on an attractive-repulsive scheme and using the efficient floating-point arithmetic which performs computations with large dynamic range and high precision. The parallel capabilities of the PSO are exploited by implementing parallel particles directly in hardware in order to decrease the running time. In addition, the attractive-repulsive technique avoids the premature convergence problem by self-adapting the swarm behavior according to its diversity. Synthesis and simulation results for benchmark test problems were performed, demonstrating the correctness of the proposed architectures. Finally, an elapsed time comparison between the hardware and software implementations shows the suitableness of the proposed architecture for embedded applications. © 2010 IEEE.

关键词： Global optimization

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Characterization of Fluoride-added Hydroxyapatite Derived from Eggshells for Dental Application 15

Characterization of Fluoride-added Hydroxyapatite Derived fr...

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15th Biomedical engineering International Conference, BMEiCON 2023

作者： Uthayaphamornwat, Vilasinee Khantachawana, Anak Kitiwan, Mettaya Srirussamee, Kasama Tunthawiroon, Phacharaphon School of Engineering Department of Biomedical Engineering Bangkok10520 Thailand Faculty of Engineering Department of Mechanical Engineering Bangkok10140 Thailand Biological Engineering Program Faculty of Engineering Bangkok10140 Thailand School of Science Department of Physics Bangkok10520 Thailand Devices and Systems for Energy and Environment Research Unit School of Science Bangkok10520 Thailand School of Engineering Department of Industrial Engineering Bangkok10520 Thailand

ISBN: (纸本)9798350345247

Hydroxyapatite (HA) is one of the potential biomaterials used for treating dental defects. It can be incorporated with fluoride to enhance its anti-caries properties, though other properties could be dependent on processing technique. Hence, this study aims to characterize the influence of sintering on the properties of fluoride-added HA derived from eggshells. FTIR and XRD techniques are used to characterize the chemical and crystal structures of the samples, whilst dissolution test is carried out to characterize material degradation in the acidic environment. The results show that sintering increased the crystallinity in both HA and fluoride-add HA (F-HA) samples, which corresponds with the enhanced stability during the dissolution test. Moreover, it is also found that the addition of fluoride could further stabilize the material structure, though the impurities found in all the samples still need to be minimized. These findings suggest that sintering and fluoride addition could potentially enhance anti-caries properties of eggshell-derived HA, which could be beneficial for dental application in future subject to further process optimization and analysis. © 2023 IEEE.

关键词： Hydroxyapatite

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Science, engineering, and technology as career paths to minority students

Science, engineering, and technology as career paths to mino...

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113th Annual ASEE Conference and Exposition, 2006

作者： Bachnak, Rafle Caruso, Korinne Esparza, Jack Méndez, Marc Texas A and M University Corpus Christi United States United States FUSE Texas A and M University - Corpus Christi Mechanical Engineering Technology Program United States Texas A and M University - Corpus Christi Control Systems Engineering Technology Program United States Texas A and M University-Corpus Christi Corpus Christi TX 78412 United States

Summer workshops to attract local area high school students to science and engineering careers have been conducted at Texas A&M-Corpus Christi for the last three years. These workshops are designed to improve the recruitment of underrepresented students in science, engineering, and technology by introducing them to college life, involve them in hands-on activities, and offering them network opportunities. Our goal is to make the activities of this project an integral part of the recruiting and training efforts and expand them to reach a larger geographical area and a higher number of underrepresented students. This paper will describe the program and present some results. © American Society for engineering Education, 2006.

关键词： engineering education

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Computational simulation of shock oscillation around a supersonic air-intake

Computational simulation of shock oscillation around a super...

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36th AIAA Fluid Dynamics Confernce

作者： Nishizawa, Uichi Kameda, Masaharu Watanabe, Yasushi Tokyo University of Agriculture and Technology Tokyo Japan Japan Aerospace Exploration Agency Tokyo Japan Department of Mechanical Systems Engineering Koganei Tokyo 184-8588 Japan Aviation Program Group Mitaka Tokyo 182-8522 Japan AIAA

ISBN: (纸本)1563478102

Unsteady flow around an external-compression air intake was Investigated numerically. Our attention was focused to shock oscillation, which is known as 'buzz', in subcritical operation. We used a two-dimensional model consisting of a wedge and a subsonic diffuser. A slit was opened for natural bleed at the entrance of the subsonic duct. The wedge angle was 10 degrees. The free stream Mach number was 1.64. Compressible viscous flow around the model was calculated using UPACS (Unified Platform for Aerospace Computational Simulation) developed at JAXA (Japan Aerospace Exploration Agency). We successfully simulated a series of flow pattern (supercritical, critical, and subcritical operations) by changing the intake mass flow rate. In the subcritical operation, multiple dominant frequencies were found in the pressure fluctuation with the buzz. Low-frequency component was caused by the acoustic resonance of the subsonic diffuser. On the other hand, high-frequency component was generated by the periodic flow separation on the wedge. This phenomenon was caused by the periodic suction of the separated air through the slit. The high-frequency component disappeared when the diffuser length was long. The natural bleed slightly suppressed the pressure fluctuation in the subsonic diffuser in a constant mass flow rate through the diffuser.

关键词： Supersonic flow

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AUTOMATED MODULAR FIXTURE PLANNING: ACCURACY, CLAMPING, AND ACCESSIBILITY ANALYSIS

AUTOMATED MODULAR FIXTURE PLANNING: ACCURACY, CLAMPING, AND ...

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ASME 1997 International mechanical engineering Congress and Exposition, IMECE 1997 - Manufacturing Science and engineering

作者： Wu, Yufeng Rong, Yiming Ma, Weidong LeClair, Steven R. Department of Mechanical and Industrial Engineering University of Illinois Urbana-Champaign United States Manufacturing Systems Program Southern Illinois University Carbondale United States Materials Directorate Wright Laboratory Wright-Patterson Air Force Base United States

ISBN: (纸本)9780791826799

Automated fixture design has become a research focus in process planning and CAD/CAM integration. An automated fixture configuration design system has been developed where when fixturing surfaces and points are specified, modular fixture components can be automatically selected and placed into position with satisfying assemble conditions. A geometric analysis has been conducted to determine the fixturing surfaces and points which provide feasible geometric constraints and assembly relationships with modular fixtures. This paper presents analyses on fixturing accuracy, clamp planning, fixturing accessibility, and clamping stability. When a fixture planning is determined, the analysis results can be applied to verify the performance of the fixture design. © 1997 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Fixtures (tooling)

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A Comparative Hardware Implementation of Histogram of Oriented Gradients as a Descriptor in Embedded Tracking of Swarm

SSRN

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SSRN 2023年

作者： Legarda, Diego Antonio Pérez, Karen Viviana Muñoz, Daniel Mauricio Department of Mechanical Engineering Mechatronics Systems Graduate Program University of Brasilia DF Brasilia70910-900 Brazil

The Histogram of Oriented Gradients (HOG) algorithm is widely utilized in image processing for tasks such as detection, classification, and tracking. However, several challenges arise when implementing this algorithm on computing platforms with limited memory and low power consumption, such as mobile robots and drones. This work presents an in-depth analysis and implementation of three innovative hardware architectures for HOG, specifically designed for real-time processing using Field programmable Gate Arrays (FPGAs) in the context of mobile robot localization. The primary focus of these architectures is to simplify the processing operations involved in gradient magnitude and orientation calculation, histogram generation, and normalization. These simplifications lead to a reduction in resource utilization and energy consumption. Experimental results conducted on a Zynq 7020 device demonstrated minimal relative error values throughout the en-Email addresseslegarda8027@*** (Diego Legarda), kperezlujan@*** (Karen Ṕerez), damuz@*** (Daniel M. Muñoz) 1Corresponding authorPreprint submitted to Journal of Parallel and Distributed Computing. July 31, 2023tire process, along with a significant execution time improvement of over 1000 times when compared to the software-based solution. © 2023, The Authors. All rights reserved.

关键词： Mobile robots

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Cauchy particle swarm optimization with dynamic adaptation applied to inverse heat transfer problem

Cauchy particle swarm optimization with dynamic adaptation a...

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2010 IEEE International Conference on systems, Man and Cybernetics, SMC 2010

作者： Mariani, Viviana Cocco Neckel, Vagner Jorge Grebogi, Rafael Bartnik Dos Santos Coelho, Leandro Department of Mechanical Engineering PPGEM Pontifical Catholic University of Paraná Imaculada Conceição 1155 80215-901 Curitiba Paraná Brazil Industrial and Systems Engineering Graduate Program PPGEPS Pontifical Catholic University of Paraná Imaculada Conceição 1155 80215-901 Curitiba Paraná Brazil

ISBN: (纸本)9781424465880

The particle swarm optimization (PSO) algorithm is a member of the wide category of swarm intelligence methods for solving global optimization problems. Its basic idea is the simulation of simplified animal social behaviors such as fish schooling and bird flocking. PSO algorithms are attracting attentions in recent years, due to their ability of keeping good balance between convergence and diversity maintenance. Several attempts have been made to improve the performance of the original PSO algorithm. In this paper, a modified version of the original PSO based on Cauchy distribution and dynamic adaptation of inertia factor, named modified PSO (MPSO), is proposed. to estimate the unknown variables of an inverse heat transfer problem. To validate the optimization performance of the proposed MPSO, an inverse heat transfer problem is illustrated and the algorithm has to estimate its unknown variables. The results testify that the MPSO can perform well in an inverse heat transfer problem. ©2010 IEEE.

关键词： Heat transfer

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A normative differential evolution approach for estimation of heat transfer coefficient during freezing treatment by inverse analysis

A normative differential evolution approach for estimation o...

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IEEE Congress on Evolutionary Computation

作者： Mariani, Viviana Cocco Klein, Carlos Eduardo Luvizotto, Luiz Guilherme Justi Dos Santos Coelho, Leandro Department of Mechanical Engineering PPGEM Pontifical Catholic University of Paran Imaculada Conceição 1155 80215-901 Curitiba Paraná Brazil Industrial and Systems Engineering Graduate Program PPGEPS Pontifical Catholic University of Paraná Imaculada Conceição 1155 80215-901 Curitiba Paraná Brazil

ISBN: (纸本)9781424478347

Among the existing meta-heuristic optimization algorithms, a well-known branch is the differential evolution (DE). DE is a powerful population-based algorithm of evolutionary computation field designed for solving global optimization problems which only has a few control parameters. With an eye to improve the performance of DE, in this paper, a DE approach combined with a cultural algorithm technique based on normative knowledge (NDE) is investigated to estimate the heat transfer coefficient during freezing treatment by inverse analysis. Numerical results for inverse heat transfer problem demonstrate the applicability and efficiency of the NDE algorithm. In this application, NDE approach outperforms a classical DE approach in terms of quality of solution. © 2011 IEEE.

关键词： Inverse problems

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