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Tracer study of CO2 enrichment for shallot growth in mini plant factory with CFD approach

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Tracer study of CO2 enrichment for shallot growth in mini pl...

International Conference on Digital Agriculture from Land to Consumers 2018, ICDALC 2018

作者： Niam, A.G. Widodo, S. Solahudin, M. Sucahyo, L. Nurjanah, S. Department of Mechanical and Biosystem Engineering Bogor Agricultural University West Java Indonesia Agricultural and Biosystem Engineering Program Bogor Agricultural University Indonesia

It has been proven that the effect of CO2 enrichment leads to faster growth and higher yields. Using environmental parameters controlling based on needs, responses, and performance of crops, CO2 level from 800 to 1500 ppm were able to accelerate the growth of shallot in mini plan factory. Therefore, CFD simulation was conducted to simulate and trace the distribution of CO2 with varying airflow inlet. Airflow inlet is two wall air conditioners (ACs) with the 2 pk specification. Both of ACs was attached at opposite walls. There were two combinations of ACs position, which are top-top (both of ACs were positioned approximately 10 cm below the ceiling) and top-center (an AC positioned approximately 10 cm below the ceiling and another positioned 60 cm below the ceiling). In the simulation, CO2 gas was injected into the inlet from 0.5 l min-1 to 2 l min-1 . The simulation was used for tracing CO2 injection and position that has the highest uniformity coefficient at the CO2 levels of around 800 ppm. It is proven through a numerical approach, the best ACs position is a top-top combination, with CO2 injected, is 2 l min-1. © Published under licence by IOP Publishing Ltd.

关键词： Carbon dioxide

Analysis of the impact of oil viscosity on the vibroacoustic signal of a planetary gearbox operating at variable load

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Diagnostyka 2020年第4期21卷 43-49页

作者： Pawlik, Pawel AGH University of Science and Technology Faculty of Mechanical Engineering and Robotics Department of Mechanics and Vibroacoustics al. A. Mickiewicza 30 Kraków30-059 Poland

The paper presents the analysis of the impact of oil viscosity on the vibroacoustic signal generated by a planetary gearbox operating at variable load. A diagnostic experiment was conducted at the laboratory rig for testing planetary gearbox which was lubricated with a dedicated ISO 150 viscosity class oil and much lower viscosity class 5W40 oil. The gearbox was subjected to two types of sinusoidal load and to a random load corresponding to the load of the main gearbox of the KWK 1500s bucket wheel excavator used in opencast mining. The diagnostic method was proposed based on the analysis of the dependence of the gearbox characteristic orders amplitudes on the load. The effectiveness of the method in detecting the changes in vibration acceleration signals caused by the oil viscosity changes was proved. © 2020 Polish Society of Technical Diagnostics. All rights reserved.

关键词： Viscosity

Breaking mechanical Holography in Combinatorial Metamaterials

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arXiv 2024年

作者： Sirote-Katz, Chaviva Palti, Ofri Spiro, Naomi Kálmán, Tamás Shokef, Yair Department of Biomedical Engineering Tel Aviv University Tel Aviv69978 Israel The Future Scientists Center Alpha Program Tel Aviv Youth University Tel Aviv69978 Israel University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Mathematics Institute of Science Tokyo H-214 2-12-1 Ookayama Tokyo Meguro-ku152-8551 Japan Hiroshima University Higashi-Hiroshima Hiroshima739-8526 Japan School of Mechanical Engineering Tel Aviv University Tel Aviv69978 Israel Center for Computational Molecular and Materials Science Tel Aviv University Tel Aviv69978 Israel Center for Physics and Chemistry of Living Systems Tel Aviv University Tel Aviv69978 Israel

Combinatorial mechanical metamaterials are made of anisotropic, flexible blocks, such that multiple metamaterials may be constructed using a single block type, and the system’s response strongly depends on the mutual orientations of the blocks within the lattice. We study a family of possible block types for the square, honeycomb, and cubic lattices. Blocks that are centrally symmetric induce holographic order, such that mechanical compatibility (meaning that blocks do not impede each other’s motion) implies bulk-boundary coupling. With them, one can design a compatible metamaterial that will deform in any desired texture only on part of its boundary. With blocks that break holographic order, we demonstrate how to design the deformation texture on the entire boundary. Correspondingly, the number of compatible holographic metamaterials scales exponentially with the boundary, while in non-holographic cases we show that it scales exponentially with the bulk. © 2024, CC BY.

关键词： Holography

Convex Parameterization and Optimization for Robust Tracking of a Magnetically Levitated Planar Positioning System

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arXiv 2021年

作者： Ma, Jun Cheng, Zilong Zhu, Haiyue Li, Xiaocong Tomizuka, Masayoshi Lee, Tong Heng Robotics and Autonomous Systems Thrust The Hong Kong University of Science and Technology Guangzhou China Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore Singapore Institute of Manufacturing Technology Singapore138634 Singapore John A. Paulson School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States Department of Mechanical Engineering University of California BerkeleyCA94720 United States

Magnetic levitation positioning technology has attracted considerable research efforts and dedicated attention due to its extremely attractive features. The technology offers high-precision, contactless, dust/lubricant-free, multi-axis, and large-stroke positioning. In this work, we focus on the accurate and smooth tracking problem of a multi-axis magnetically levitated (maglev) planar positioning system for a specific S-curve reference trajectory. The floating characteristics and the multi-axis coupling make accurate identification of the system dynamics difficult, which lead to a challenge to design a high performance control system. Here, the tracking task is achieved by a 2-Degree of Freedom (DoF) controller consisting of a feedforward controller and a robust stabilizing feedback controller with a prescribed sparsity pattern. The approach proposed in this paper utilizes the basis of an H∞ controller formulation and a suitably established convex inner approximation. Particularly, a subset of robust stabilizable controllers with prescribed structural constraints is characterized in the parameter space, and so thus the re-formulated convex optimization problem can be easily solved by several powerful numerical algorithms and solvers. With this approach, the robust stability of the overall system is ensured with a satisfactory system performance despite the presence of parametric uncertainties. Furthermore, experimental results clearly demonstrate the effectiveness of the proposed approach. Copyright © 2021, The Authors. All rights reserved.

关键词： Convex optimization

Admittance Control based Hemiplegic Exoskeleton Motion Control

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Admittance Control based Hemiplegic Exoskeleton Motion Contr...

2022 IEEE International Conference on Real-Time Computing and robotics, RCAR 2022

作者： He, Bailin Zhou, Xin Huai, Yaping Liu, Jiaqing Li, Pengbo Wang, Can Wu, Xinyu Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Department of Mechanical and Automation Engineering Chinese University of Hong Kong Hong Kong Shenzhen College of Advanced Technology University of Chinese Academy of Sciences Shenzhen518055 China Guangdong-Hong Kong-Macao Joint Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China Department of Rehabilitation Medicine Shenzhen Longhua District Central Hospital Shenzhen518000 China

ISBN: (数字)9781665469838

ISBN: (纸本)9781665469838

In this paper, a method based on admittance control is developed to improve patients' comfort wearing an exoskeleton robot for rehabilitation training. In our previous work, we designed a modular and convenient hemiplegic exoskeleton robot. The mechanical structure will cause stiffness when it comes to contact with the human body in practical applications. We introduced admittance control to improve the flexibility of the exoskeleton robot and improve the subjects' comfort. This paper considers coupling of model between the exoskeleton and the human body as the human-computer interaction force of the system at the main human-computer interaction point. Measuring the interaction force between exoskeleton members and limbs, the work uses the virtual admittance model to correct the system's inherent characteristics and studies the control method's stability with Lyapunov's theory. The experiment collected the subject movement information which was converted the movement information of the exoskeleton. Human-computer interaction forces in the thigh and calf were measured while the exoskeleton assisted the subject's movement. The experimental results show that adding the admittance controller reduces the human-computer interaction force from 5g to 2g and 6g to 3g, respectively. © 2022 IEEE.

关键词： Human computer interaction

A Topological Approach to Gait Generation for Biped Robots

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arXiv 2020年

作者： Rosa, Nelson Lynch, Kevin M. the Department of Mechanical Engineering the Center for Robotics and Biosystems the Northwestern Institute on Complex Systems Northwestern University EvanstonIL60208 United States

This paper describes a topological approach to generating families of open- and closed-loop walking gaits for underactuated 2D and 3D biped walkers subject to configuration inequality constraints, physical holonomic constraints (e.g., closed-loop linkages), and virtual holonomic constraints (user-defined constraints enforced through feedback control). Our method constructs implicitly-defined manifolds of feasible periodic gaits within a state-time-control space that parameterizes the biped’s hybrid trajectories. Since equilibrium configurations of the biped often belong to such manifolds, we use equilibria as "templates" from which to grow the gait families. Equilibria are reliable seeds for the construction of gait families, eliminating the need for random, intuited, or bio-inspired initial guesses at feasible trajectories in an optimization framework. We demonstrate the approach on several 2D and 3D biped walkers. Copyright © 2020, The Authors. All rights reserved.

关键词： Constraint theory

Metaclusters for the Full Control of mechanical Waves

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Physical Review Applied 2021年第1期15卷 014051-014051页

作者： Pawel Packo Andrew N. Norris Dani Torrent Department of Robotics and Mechatronics AGH - University of Science and Technology Al. A. Mickiewicza 30 Krakow 30-059 Poland Mechanical and Aerospace Engineering Rutgers University Piscataway New Jersey 08854-8058 USA GROC UJI Institut de Noves Tecnologies de la Imatge (INIT) Universitat Jaume I Castelló 12071 Spain

We present a method for the control of waves based on inverse multiple scattering theory. Conceived as a generalization of the concept of metagrating, we call metaclusters to a finite set of scatterers whose position and properties are obtained by inverse design once we have defined their response to some external incident field. The particular focus is on designing passive metaclusters that do not require an external source of energy. The method is applied to the propagation of flexural waves in thin plates, and to the design of far-field patterns, although its generalization to acoustic or electromagnetic waves is straightforward. Numerical examples are presented to the design of uni- and bidirectional “anomalous scatterers,” which will bend the scattering energy along a specific direction, “odd pole” scatterers, whose radiation pattern presents an odd number of poles, and to the generation of vortical patterns. Finally, some considerations about the optimal design of these metaclusters are discussed.

关键词： Acoustic metamaterials Acoustic wave phenomena Classical mechanics Metamaterials Optical & microwave phenomena Elastic wave theory Light scattering

Dynamics and aerial attitude control for rapid emergency deployment of the agile ground robot AGRO

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arXiv 2020年

作者： Gonzalez, Daniel J. Lesak, Mark C. Rodriguez, Andres H. Cymerman, Joseph A. Korpela, Christopher M. Robotics Research Center Department of Electrical Engineering and Computer Science Army Cyber Institute Department of Civil and Mechanical Engineering United States Military Academy West PointNY10996 United States

In this work we present a Four-Wheeled Independent Drive and Steering (4WIDS) robot named AGRO and a method of controlling its orientation while airborne using wheel reaction torques. This is the first documented use of independently steerable wheels to both drive on the ground and achieve aerial attitude control when thrown. Inspired by a cat’s self-righting reflex, this capability was developed to allow emergency response personnel to rapidly deploy AGRO by throwing it over walls and fences or through windows without the risk of it landing upside down. It also allows AGRO to drive off of ledges and ensure it lands on all four wheels. We have demonstrated a successful thrown deployment of AGRO. A novel parametrization and singularity analysis of 4WIDS kinematics reveals independent yaw authority with simultaneous adjustment of the ratio between roll and pitch authority. Simple PD controllers allow for stabilization of roll, pitch, and yaw. These controllers were tested in a simulation using derived dynamic equations of motion, then implemented on the AGRO prototype. An experiment comparing a controlled and non-controlled fall was conducted in which AGRO was dropped from a height of 0.85 m with an initial roll and pitch angle of 16 degrees and -23 degrees respectively. With the controller enabled, AGRO can use the reaction torque from its wheels to stabilize its orientation within 402 milliseconds. Copyright © 2020, The Authors. All rights reserved.

关键词： Wheels

Adaptive finite-time synchronized control of multi-robotic fiber placement system with model uncertainties and disturbances

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ISA Transactions 2025年

作者： Zhang, Ronghua Wang, Yaonan Xie, Wenfang Li, Pengcheng Tan, Haoran Jiang, Yiming College of Electrical and Information Engineering Hunan University Hunan Changsha410082 China Department of Mechanical Industrial and Aerospace Concordia University MontrealQCH3G2W1 Canada College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Jiangsu Nanjing210016 China School of Robotics Hunan University Hunan Changsha410082 China National Engineering Laboratory of Robot Visual Perception and Control Technology Hunan University Hunan Changsha410082 China

The use of multiple robots to manufacture composite components represents a critical development direction for fiber placement systems (FPSs). In multi-robotic fiber placement systems (MRFPSs) with heterogeneous mechanical structures, robots collaborate to perform fiber placement tasks. Consequently, robot synchronization emerges as a primary factor in determining the performance of the fiber placement process. However, the difficulty in establishing accurate system models and the presence of disturbances are two significant challenges to achieving precise robot synchronization. Additionally, the system is expected to exhibit desirable dynamic characteristics, such as finite-time error convergence. To address these issues and requirements, we propose a novel adaptive finite-time synchronization control (AFSC) algorithm for the system. Specifically, a finite-time sliding mode observer is developed to handle kinematic uncertainty. A novel fast non-singular terminal sliding mode (FNTSM) manifold is constructed in the AFSC algorithm. Moreover, the control algorithm integrates an adaptive law to handle dynamic uncertainty and an adaptive term to counteract disturbances. Performance analysis demonstrates that the AFSC ensures that the coupled, synchronization, and tracking errors converge to zero within finite time. Furthermore, simulations and experiments are conducted to validate the effectiveness of the AFSC algorithm. © 2025 Elsevier Ltd

关键词： Multipurpose robots