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SSRN 2023年

作者： Wu, Shengqi Li, Hongjiang Wooldridge, Margaret Pu, Tianhao School of Aeronautics and Astronautics Shanghai Jiao Tong University Shanghai200240 China Shanghai Jiao Tong University Sichuan Research Institute Chengdu610041 China Research and Advanced Engineering Ford Motor Company DearbornMI48124 United States Department of Mechanical Engineering Department of Aerospace Engineering University of Michigan Ann ArborMI48109 United States

Six GDI injectors were studied in this study, including four multi-hole injectors with different nozzle structures but identical design-intent spray patterns, and two advanced injectors fabricated by 3D printing. A numerical modeling approach based on the volume of fluid (VOF) method was used to simulate in-nozzle flow of hole type injectors, and various optical techniques were applied to quantify the spray characteristics. Results showed larger counterbore diameter did not induce differences in the nozzle internal flow and resulted in identical static flow rate and average flow velocity. However, air entrainment into the counterbore was enhanced for the nozzle with the larger counterbore, which accelerated spray breakup and atomization. For the injector with the smaller nozzle diameter, stronger in-nozzle cavitation was observed, and the mean flow velocity was slightly higher. In addition, the surface area to volume ratio of the jet was 15% larger, which was beneficial to jet breakup and atomization. As a result, spray from the injector with smaller nozzles was wider, shorter and better atomized. No obvious differences in the in-nozzle flow and spray characteristics were identified for the two injectors with different nozzle taper angles. Enhanced spray atomization led to stronger plume-to-plume interaction and spray collapse even at cold conditions, which resulted in different spray structures and fuel distributions compared with the baseline injector. At hot conditions, difference in spray structure induced by nozzle geometry of multi-hole GDI injectors diminished gradually with increasing fuel temperature. For advanced fuel injectors, the spray penetration can be reduced and spray angle can be increased significantly at cold conditions compared with the multi-hole injector. At superheated conditions, spray collapse can be suppressed significantly and the over-penetrating issue can be solved. © 2023, The Authors. All rights reserved.

关键词： Numerical methods

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Fixed-Time Parameter Adaptation for Safe control Synthesis *

arXiv

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arXiv 2022年

作者： Black, Mitchell Arabi, Ehsan Panagou, Dimitra Department of Aerospace Engineering University of Michigan Ann ArborMI48109 United States Ford Research and Advanced Engineering Ford Motor Company DearbornMI48124 United States Department of Robotics Department of Aerospace Engineering University of Michigan Ann ArborMI48109 United States

This paper introduces a parameter adaptation-based control law for a class of nonlinear, control-affine, safety-critical systems subject to additive, parameter-affine model uncertainty. It is shown that the uncertainty is learned in fixed-time, i.e., within a finite time independent of the initial parameter estimates, without requiring persistence of excitation or rank conditions on the associated regressor matrix. A monotonically decreasing bound on the error of the estimated uncertainty is derived and used in the proposed control barrier function-based control law for guaranteed safety of the system trajectories. It is then proven that the parameter adaptation law is robust to bounded measurement noise and non-parametric perturbations to the system in that the estimated uncertainty still converges to a known neighborhood of the true uncertainty in fixed-time. The advantages of the approach are highlighted in a comparative numerical study, and the method is validated on a quadrotor trajectory-tracking problem subject to safety requirements and an unknown wind field. © 2022, CC BY.

关键词： Numerical methods

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Split injection spray characterization of three different types of GDI injectors at various fuel temperatures 14

Split injection spray characterization of three different ty...

引用

14th International Conference on Liquid Atomization and Spray Systems, ICLASS 2018

作者： Wu, S. Meinhart, M. Yi, J. Department of Mechanical Engineering University of Michigan Ann ArborMI United States Powertrain Research and Advanced Engineering Ford Motor Company DearbornMI United States

Split injection strategy has been experimentally and numerically proven to reduce exhaust PM/PN emissions of spark ignition direct injection engines due to less fuel impingement on the cylinder wall or piston. In this study, various closely coupled split injection strategies are investigated on three different types of GDI injectors by using high speed Mie-scattering and schlieren methods. Three different injectors are a 6-hole injector, a 4-slot injector and a 1-slot injector. Various split injection strategies, including single injection, double injection, triple injection and quadruple injection were investigated. Fuel pressure was set at 100 bar, and ambient pressure was maintained at 50 kPa (abs.). n-Heptane was chosen as test fuel, and fuel temperature ranged from 20 ℃ to 140 ℃. For different split injections, dwell time between injections was set at 0.4 ms, and each injection duration was set to the same for each injection event. Total injection mass was kept at 24.55mg of the 6-hole injector (fuel temperature at 20 ℃). Results show that split injection strategy can reduce the liquid spray penetration, which is more obvious when using quadruple injection strategy. However, by using split injection strategy, fuel delivered later moved faster than the fuel delivered at the beginning of the injection. Fuel distribution was mainly governed by injector configuration when fuel temperature was lower than 90 ℃. However, fuel plumes of three injectors all collapsed to the central line of spray when fuel temperature was higher than 120 ℃ regardless of split injection strategy, which resulted in longer spray penetration of 6-hole injector and 4-slot injector, but shorter spray penetration of the 1-slot injector. By using triple or quadruple injection strategies, the penetration of severe collapsed fuel spray was even shorter than that of fuel spray at fuel temperature of 20 ℃ when using single injection. © 2018 Solar Turbines Incorporated.

关键词： Fuels

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Optimization of retting and extraction through constitutive material modelling of plant stems for variability reduction in extracted natural fibers 36

Optimization of retting and extraction through constitutive ...

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36th Technical Conference of the American Society for Composites 2021: Composites Ingenuity Taking on Challenges in Environment-Energy-Economy, ASC 2021

作者： Singhal, Anshul Langhorst, Amy Bansal, Ankush Banu, Mihaela Taub, Alan Materials Science and Engineering The University of Michigan 2300 Hayward St Ann ArborMI48109 United States Research and Advanced Engineering Ford Motor Company 2101 Village Rd DearbornMI48124 United States Mechanical Engineering The University of Michigan 2350 Hayward St Ann ArborMI48109 United States

ISBN: (纸本)9781713837596

Natural plant fibers compared to glass fibers can provide a cost effective, lightweight and carbon negative reinforcement for polymer composites. However, the current commercial fiber extraction process induces defects including middle lamellae weakening during retting and kink bands during mechanical working. This leads to high variability in mechanical properties, making these fibers less favorable for structural applications at industrial scale. The aim of current research is to reduce this variability by studying the underlying mechanisms of natural fiber extraction to minimize fiber damage occurring at various steps in the process. In this study, flax stems were retted using the conventional dew/field and lab scale controlled enzymatic retting. The hand decorticated fibers from both methods were compared and enzymatic retting showed promising results in producing fine and uniform fibers as compared to fibers extracted by dew retting. To establish the constitutive parameters of the fibers for Finite Element Modeling (FEM), single retted flax stems were compression tested using a Texture Analyzer. This data can serve as the basis for modeling the mechanical deformation of plant stems passing through breaking rollers which is the first step in extraction after retting. The goal is to optimize the roller design and process conditions required to extract fibers with minimal damage and variability. © 36th Technical Conference of the American Society for Composites 2021: Composites Ingenuity Taking on Challenges in Environment-Energy-Economy, ASC 2021.

关键词： Extraction

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Occlusion Handling for Industrial Robots

Occlusion Handling for Industrial Robots

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2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

作者： Ling Zhu Meghna Menon Mario Santillo Gregory Linkowski Ford Motor Company Research and Advanced Engineering Dearborn MI United States

ISBN: (数字)9781728162126

ISBN: (纸本)9781728162133

Industrial robots contain minimal sensing capability beyond recognition of their internal state. It is critical that an external vision system should cover the designated robot work space with awareness of blind spots and occlusions. This work presents two mechanisms to handle occlusions in an external multi-robot vision system: occlusion-aware optimal sensor positioning, and event-driven occlusion detection. When deploying sensors to the system, various scenarios are considered during optimization to reduce potential occlusions and increase sensor coverage. These methods are tested on a working cell with three industrial robot arms. The experimental results demonstrate the effectiveness of the proposed scenario-based multi-objective optimization for sensor positioning. Once the sensors are deployed, occlusion detection is actively triggered prior to robot path planning.

关键词： Service robots Machine vision Robot sensing systems Path planning Task analysis Robots Optimization

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Following a dynamic object through a transient response adjustable MPC (extended version)

TechRxiv

引用

TechRxiv 2020年

作者： Hong, Sanghyun Miller, Justin Lu, Jianbo Research & Advanced Engineering Ford Motor Company DearbornMI United States

Robots can help humans fulfill various tasks in efficient and safe manners. For example, robots can navigate while loaded with packages to assist humans in delivery tasks, and they can also collaborate with Autonomous Vehicles (AV) to reach areas that AVs cannot drive. As robots are expected to interact with humans, vehicles, and other robots, following these dynamic objects is considered a crucial functionality. This paper will propose a mobile robot motion controller for following a dynamic object based on downscaled Model Predictive control (MPC). It can reflect the dynamics of object for an appropriate response speed and ensure safety of mobile robot against predicted risks. In addition, an adaptive prediction time horizon will be proposed to improve robustness in following a dynamic object. The proposed motion controller is demonstrated through extensive simulations and real-time experiments of a test mobile robot. © 2020, CC BY-NC-SA.

关键词： Model predictive control

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Gap Opening controller Design to Accommodate Merges in Cooperative Autonomous Platoons ⁎

引用

IFAC-PapersOnLine 2020年第2期53卷 15294-15299页

作者： Wouter J. Scholte Peter W.A. Zegelaar Henk Nijmeijer Mechanical Engineering Department Eindhoven University of Technology Eindhoven Netherlands Ford Motor Company Research and Advanced Engineering Europe Aachen Germany

In this paper, a cooperative platoon-based gap opening controller is developed. The intended application is gap creation in cooperative platoons to accommodate merges with spatial restrictions. Therefore, the main objective is to execute the maneuver in a predefined time. The controller design is based on a regular cooperative adaptive cruise control algorithm with an additional feedforward term for a desired gap. Experimental validation of the controller is performed with small mobile robots. The proposed control strategy is capable of opening the gap in a predefined time. In future work, this strategy can be used in the design of a merging algorithm specifically for CACC platoons.

关键词： Autonomous vehicles Automotive control Closed-loop gain PD controllers Trajectory planning

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A Split-Future MPC Algorithm for Lithium-Ion Battery Cell-Level Fast-Charge control

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IFAC-PapersOnLine 2020年第2期53卷 12459-12464页

作者： Marcelo A. Xavier Aloisio Kawakita de Souza M. Scott Trimboli Research & Advanced Engineering Ford Motor Company Dearborn MI 48124 USA Department of Electrical and Computer Engineering University of Colorado Colorado Springs Colorado Springs CO 80918 USA

Constrained predictive control has emerged as a viable candidate for generating optimal real-time charging strategies for lithium ion batteries. Able to conform to hard constraints on problem variables, model predictive control (MPC) formulates an optimal 2-norm solution at each time step and can thus assure safe and reliable fast-charge operation. Standard MPC implementations make certain simplifying assumptions regarding future control actions beyond a specified control horizon. This paper demonstrates the potential gains that can be realized for the battery charge problem by relaxing these assumptions.

关键词： control of renewable energy resources model predictive control lithium-ion battery

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Performance analysis of cellular-V2X with adaptive and selective power control

arXiv

引用

arXiv 2020年

作者： Saifuddin, Md Zaman, Mahdi Toghi, Behrad Fallah, Yaser P. Rao, Jayanthi University of Central Florida OrlandoFL United States Research and Advanced Engineering Ford Motor Company DearbornMI United States

LTE based Cellular Vehicle-To-Everything (C-V2X) allows vehicles to communicate with each other directly without the need for infrastructure and is expected to be a critical enabler for connected and autonomous vehicles. V2X communication based safety applications are built on periodic broadcast of basic safety messages with vehicle state information. Vehicles use this information to identify collision threats and take appropriate countermeasures. As the vehicle density increases, these broadcasts can congest the communication channel resulting in increased packet loss;fundamentally impacting the ability to identify threats in a timely manner. To address this issue, it is important to incorporate a congestion control mechanism. Congestion management scheme based on rate and power control has proved to be effective for DSRC. In this paper, we investigate the suitability of similar congestion control to C-V2X with particular focus on transmit power control. In our evaluation, we include periodic basic safety messages and high priority event messages that are generated when an event such as hard braking occurs. Our study reveals that while power control does not improve packet delivery performance of basic safety messages, it is beneficial to high priority event message delivery. In this paper, we investigate the reasons for this behavior using simulations and analysis. Copyright © 2020, The Authors. All rights reserved.

关键词： Vehicle to Everything

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MPC-based Vibration control and Energy Harvesting Using an Electromagnetic Vibration Absorber With Inertia Nonlinearity

MPC-based Vibration Control and Energy Harvesting Using an E...

引用

American control Conference

作者： Kaian Chen Zhaojian Li Wei-Che Tai Kai Wu Yan Wang department of Mechanical Engineering Michigan State University East Lansing MI USA Research & Advanced Engineering Ford Motor Company Dearborn MI USA

ISBN: (数字)9781538682661

ISBN: (纸本)9781538682678

Simultaneous vibration control and energy harvesting of vehicle suspensions has attracted great research interests over the past decades. However, existing frameworks tradeoff suspension performance for energy recovery and are only responsive to narrow-bandwidth vibrations. In this paper, a new energy-regenerative vibration absorber (ERVA) using a ball-screw mechanism is investigated. The ERVA system is based on a rotary electromagnetic generator with adjustable nonlinear rotational inertia which passively increases the moment of inertia as the vibration amplitude increases. This structure is effective for energy harvesting and vibration control without increasing the suspension size. Furthermore, a nonlinear model predictive controller (NMPC) is applied to the system for further performance enhancement where we exploit road pro le information as a preview. The performance of NMPC-based ERVA is demonstrated in a number of simulations and superior performance is demonstrated.

关键词： Vibrations Electromagnetics Suspensions Generators Force Mathematical model Energy harvesting

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