Ball Drive Configurations and Kinematics for Holonomic Ground Mobility

2017 ◽  
Author(s):  
Biruk A. Gebre ◽  
Kishore Pochiraju
Keyword(s):  
Design Space ◽  
Kinematic Model ◽  
Design Parameters ◽  
Actuation Force ◽  
Confined Spaces ◽  
Naming Convention ◽  
Trade Offs ◽  
Vehicle Velocity ◽  
And Performance ◽  
Selection Of

Holonomic motion is desired for mobile ground robots and vehicles as it provides omnidirectional maneuvering capabilities, which can simplify the task of navigating around obstacles in confined spaces and unstructured environments. Mobility platforms that utilize spherical wheels are gaining popularity and interest due to the agile maneuvering and ground traversal capabilities they enable for mobility platforms. Ball-driven mobility platforms have a rich design space as various design parameters are available that can modify the physical and performance characteristics of the platforms. Various configurations for ball-driven mobility platforms are presented along with a generalized kinematic model that can be used for calculating motor velocities for a desired vehicle velocity. A naming convention is also presented in the paper for differentiating between configurations used for ball-driven mobility platforms. Metrics such as platform footprint, platform stability, and actuation force and efficiency are used to compare the configurations and to highlight some of the trade-offs associated with the selection of a configuration. Promising configurations are highlighted based on the metrics selected for the comparisons.

Preliminary Design and Performance of Counter Rotating Turbines for Open Rotors: Part II — 0-D Methodology and Case Study for a 160 PAX Aircraft

2016 ◽  
Author(s):  
Pablo Bellocq ◽  
Inaki Garmendia ◽  
Jordane Legrand ◽  
Vishal Sethi
Keyword(s):  
Design Methodology ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Preliminary Design ◽  
Regulatory Constraints ◽  
Trade Offs ◽  
And Performance ◽  
The Impact

Direct Drive Open Rotors (DDORs) have the potential to significantly reduce fuel consumption and emissions relative to conventional turbofans. However, this engine architecture presents many design and operational challenges both at engine and aircraft level. At preliminary design stages, a broad design space exploration is required to identify potential optimum design regions and to understand the main trade offs of this novel engine architecture. These assessments may also aid the development process when compromises need to be performed as a consequence of design, operational or regulatory constraints. Design space exploration assessments are done with 0-D or 1-D models for computational purposes. These simplified 0-D and 1-D models have to capture the impact of the independent variation of the main design and control variables of the engine. Historically, it appears that for preliminary design studies of DDORs, Counter Rotating Turbines (CRTs) have been modelled as conventional turbines and therefore it was not possible to assess the impact of the variation of the number of stages (Nb) of the CRT and rotational speed of the propellers. Additionally, no preliminary design methodology for CRTs was found in the public domain. Part I of this two-part publication proposes a 1-D preliminary design methodology for DDOR CRTs which allows an independent definition of both parts of the CRT. A method for calculating the off-design performance of a known CRT design is also described. In Part II, a 0-D design point efficiency calculation for CRTs is proposed and verified with the 1-D methods. The 1-D and 0-D CRT models were used in an engine control and design space exploration case study of a DDOR with a 4.26m diameter an 10% clipped propeller for a 160 PAX aircraft. For this application: • the design and performance of a 20 stage CRT rotating at 860 rpm (both drums) obtained with the 1-D methods is presented. • differently from geared open rotors, negligible cruise fuel savings can be achieved by an advanced propeller control. • for rotational speeds between 750 and 880 rpm (relatively low speeds for reduced noise), 22 and 20 stages CRTs are required. • engine weight can be kept constant for different design rotational speeds by using the minimum required Nb. • for any target engine weight, TOC and cruise SFC are reduced by reducing the rotational speeds and increasing Nb (also favourable for reducing CRP noise). However additional CRT stages increase engine drag, mechanical complexity and cost.

scholarly journals Numerical verification of variable friction cladding connection for multihazard mitigation

2020 ◽  
pp. 107754632092393
Author(s):  
Yongqiang Gong ◽  
Liang Cao ◽  
Simon Laflamme ◽  
James Ricles ◽  
Spencer Quiel ◽  
...  
Keyword(s):  
Sliding Friction ◽  
Design Procedure ◽  
Design Parameters ◽  
Numerical Verification ◽  
Structural System ◽  
Passive Energy Dissipation ◽  
Variable Friction ◽  
Friction Cladding ◽  
And Performance ◽  
Selection Of

The motion of cladding systems can be leveraged to mitigate natural and man-made hazards. The literature counts various examples of connections enhanced with passive energy dissipation capabilities at connections. However, because such devices are passive, their mitigation performance is typically limited to specific excitations. The authors have recently proposed a novel variable friction cladding connection capable of mitigating hazards semi-actively. The variable friction cladding connection is engineered to transfer lateral forces from the cladding element to the structural system. Its variation in friction force is generated by a toggle-actuated variable normal force applied onto sliding friction plates. In this study, a multiobjective motion-based design methodology integrating results from the previous work is proposed to leverage the variable friction cladding connection for nonsimultaneous wind, seismic, and blast hazard mitigation. The procedure starts with the quantification of each hazard and performance objectives. It is followed by the selection of dynamic parameters enabling prescribed performance under wind and seismic loads, after which an impact rubber bumper is designed to satisfy motion requirements under blast. Last, the peak building responses are computed and iterations conducted on the design parameters on the satisfaction of the motion objectives. The motion-based design procedure is verified through numerical simulations on two example buildings subjected to the three nonsimultaneous hazards. The performance of the variable friction cladding connection is also assessed and compared against different control cases. Results show that the motion-based design procedure yields a conservative design approach in meeting all of the motion requirements and that the variable friction cladding connection performs significantly well at mitigating vibrations.

scholarly journals A Framework for Optimization of Hybrid Aircraft

2019 ◽  
Author(s):  
Xin Zhao ◽  
Smruti Sahoo ◽  
Konstantinos Kyprianidis ◽  
Sharmila Sumsurooah ◽  
Giorgio Valente ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Aircraft Structure ◽  
Simulation And Optimization ◽  
Trade Offs ◽  
And Performance ◽  
Full Design ◽  
Aircraft Conceptual Design

Abstract To achieve the goals of substantial improvements in efficiency and emissions set by Flightpath 2050, fundamentally different concepts are required. As one of the most promising solutions, electrification of the aircraft primary propulsion is currently a prime focus of research and development. Unconventional propulsion sub-systems, mainly the electrical power system, associated thermal management system and transmission system, provide a variety of options for integration in the existing propulsion systems. Different combinations of the gas turbine and the unconventional propulsion sub-systems introduce different configurations and operation control strategies. The trade-off between the use of the two energy sources, jet fuel and electrical energy, is primarily a result of the trade-offs between efficiencies and sizing characteristics of these sub-systems. The aircraft structure and performance are the final carrier of these trade-offs. Hence, full design space exploration of various hybrid derivatives requires global investigation of the entire aircraft considering these key propulsion sub-systems and the aircraft structure and performance, as well as their interactions. This paper presents a recent contribution of the development for a physics-based simulation and optimization platform for hybrid electric aircraft conceptual design. Modeling of each subsystem and the aircraft structure are described as well as the aircraft performance modeling and integration technique. With a focus on the key propulsion sub-systems, aircraft structure and performance that interfaces with existing conceptual design frameworks, this platform aims at full design space exploration of various hybrid concepts at a low TRL level.

Selection of One-Dimensional Design Parameter ‘Reaction Degree’ for 1st Stage of a Cooled Gas Turbine

2012 ◽  
Author(s):  
Hina Noor ◽  
Magnus Genrup ◽  
Torsten Fransson
Keyword(s):  
Mass Flow ◽  
Design Parameter ◽  
Design Tool ◽  
Performance Estimation ◽  
Design Parameters ◽  
Flow Angle ◽  
One Dimensional ◽  
And Performance ◽  
Reaction Degree ◽  
Selection Of

The recommendations available today in open literature for the choice of design parameter such as flow coefficient, stage loading and reaction degree incorporates mainly the influence of aerodynamics loss on efficiency. However, it is difficult to find the recommendation relating the influence of not only the aerodynamics loss but also cooling mass flow and cooling losses on varying most influential design parameters. In this paper, preliminary design and performance guidelines are presented for a cooled turbine stage using the 1D design tool LUAXT. The intention is to provide recommendations on the selection of design parameters, mainly reaction degree, which is found to be highly influenced by not only the aerodynamics loss but also the cooling mass flow and cooling loss such as in 1st stage of a High Pressure Turbines (HPT). The One-Dimensional (1D) design methods used to perform this task are verified and validated against experimental test data. A comparison of different loss models has been performed to provide most accurate outcomes for certain tested ranges. Based on the outcomes of this study, ‘Craig & Cox’ loss model has been considered to perform subsequent investigations for HPT design and performance estimation while formulating a parametric study. From this study, the design recommendations for the selection of performance parameter reaction degree are developed for cooled turbines. The results shows that for a HPT 1st stage, the recommended reaction degree range of 0.20 to 0.37 seems to provide the optimum stage design when chosen for stage loading in between 1.40 to 1.80 along with the stator exit flow angle in range of 74° to 78°.

The Analysis of the Influence of the Design Parameters on the Performance Characteristics of a Mini UAV

2013 ◽  
Vol 198 ◽  
pp. 248-253 ◽  
Author(s):  
Andrzej Majka
Keyword(s):  
Calculation Model ◽  
Optimal Choice ◽  
Performance Characteristics ◽  
Design Parameters ◽  
Technical Parameters ◽  
Performance Effectiveness ◽  
Aerial Vehicle ◽  
And Performance ◽  
Optimal Designing ◽  
Selection Of

In the conditions of the growing intensity of the UAV usage one of the most important problems is the improvement of their technical and performance effectiveness. It can be achieved applying the advanced methods of optimal designing. Apart from constructing an appropriate calculation model of the UAV, such an approach requires separating a group of decisive parameters, determining the limits and choosing the criterion of optimization. The precision and the range of use of the constructed calculation model must be adequate to a particular task allowing the optimal choice of characteristics of an aerial vehicle. Selection of the design parameters requires answering the question which technical parameters (geometrical, constructional etc.) of the UAV influence the performance characteristics of the aircraft positively. Analyzing the gradients of the performance characteristics change depending on the change in the design parameters, it is possible to determine the level of precision when determining the values and formulating the condition of finishing the optimization calculations. The aim of this work was to analyze the influence of selected design parameters on the performance characteristics of a mini UAV.

scholarly journals Multi-objective constrained Bayesian optimization for structural design

2020 ◽  
Author(s):  
Alexandre Mathern ◽  
Olof Skogby Steinholtz ◽  
Anders Sjöberg ◽  
Magnus Önnheim ◽  
Kristine Ek ◽  
...  
Keyword(s):  
Structural Design ◽  
Current Trend ◽  
Bayesian Optimization ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Structural Concrete ◽  
Design Problems ◽  
Multi Objective ◽  
Trade Offs ◽  
And Performance

Abstract The planning and design of buildings and civil engineering concrete structures constitutes a complex problem subject to constraints, for instance, limit state constraints from design codes, evaluated by expensive computations such as finite element (FE) simulations. Traditionally, the focus has been on minimizing costs exclusively, while the current trend calls for good trade-offs of multiple criteria such as sustainability, buildability, and performance, which can typically be computed cheaply from the design parameters. Multi-objective methods can provide more relevant design strategies to find such trade-offs. However, the potential of multi-objective optimization methods remains unexploited in structural concrete design practice, as the expensiveness of structural design problems severely limits the scope of applicable algorithms. Bayesian optimization has emerged as an efficient approach to optimizing expensive functions, but it has not been, to the best of our knowledge, applied to constrained multi-objective optimization of structural concrete design problems. In this work, we develop a Bayesian optimization framework explicitly exploiting the features inherent to structural design problems, that is, expensive constraints and cheap objectives. The framework is evaluated on a generic case of structural design of a reinforced concrete (RC) beam, taking into account sustainability, buildability, and performance objectives, and is benchmarked against the well-known Non-dominated Sorting Genetic Algorithm II (NSGA-II) and a random search procedure. The results show that the Bayesian algorithm performs considerably better in terms of rate-of-improvement, final solution quality, and variance across repeated runs, which suggests it is well-suited for multi-objective constrained optimization problems in structural design.

Hybrid-Electric Powertrain Design Evaluation for Future Tactical Truck Vehicle Systems

2006 ◽  
Author(s):  
Pierluigi Pisu ◽  
Lorenzo Serrao ◽  
Codrin-Gruie Cantemir ◽  
Giorgio Rizzoni
Keyword(s):  
Large Scale ◽  
Design Space Exploration ◽  
Design Space ◽  
Combustion Engine ◽  
Space Exploration ◽  
Trade Offs ◽  
And Performance ◽  
Storage Batteries ◽  
Hybrid Electric Powertrain ◽  
Scale Design

The article presents the results of a large-scale design space exploration for two vehicles part of the Future Tactical Truck System (FTTS) family. A multi-objective optimization tool is presented, that allows designers to make appropriate trade-offs amongst different vehicle characteristics, on the basis of simulations run varying vehicle parameters over a broad range of values. Several powertrain architectures were taken into consideration for the Maneuver Sustainment Vehicle (MSV) and Utility Vehicle (UV). The architecture alternatives include the number of axles in the vehicle (2 or 3), the number of electric motors per axle (1 or 2), the type of internal combustion engine, the type and quantity of devices for energy storage (batteries, electrochemical capacitors or both together). A control strategy for energy management was developed to provide efficiency and performance. The control parameters are tunable and have been included into the design space exploration.

scholarly journals Exploration of Axial Fan Design Space with Data-Driven Approach

2019 ◽  
Vol 4 (2) ◽  
pp. 11
Author(s):  
Gino Angelini ◽  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Lorenzo Tieghi
Keyword(s):  
Design Space ◽  
Similarity Theory ◽  
Principal Component ◽  
Design Parameters ◽  
Meridional Plane ◽  
Axial Fan ◽  
Axial Fans ◽  
Latent Structures ◽  
And Performance ◽  
Turbomachinery Design

Since the 1960s, turbomachinery design has mainly been based on similarity theory and empirical correlations derived from experimental data and manufacturing experience. Over the years, this knowledge was consolidated and summarized by parameters such as specific speed and diameters that represent the flow features on the meridional plane, hiding however the direct correlations between all the actual design parameters (e.g., blade number or hub-to-tip ratio). Today a series of statistical tools developed for big data analysis sheds new light on correlations among turbomachinery design and performance parameters. In the following article we explore a dataset of over 10,000 axial fans by means of principal component analysis and projection to latent structures. The aim is to find correlations between design and performance features and comment on the capabilities of this approach to give new insights on the design space of axial fans.

Performance Analysis and Parametric Studies of Nose Landing Gear Shimmy Dampers

2019 ◽  
Author(s):  
Mohsen Rahmani ◽  
Kamran Behdinan
Keyword(s):  
Performance Analysis ◽  
Passive Control ◽  
Control Strategies ◽  
Landing Gear ◽  
Design Parameters ◽  
Trade Offs ◽  
Time Histories ◽  
Parametric Studies ◽  
And Performance ◽  
Stiffness And Damping

Abstract Self-induced mechanical oscillation of nose landing gears designated as shimmy is a major safety challenge for aircrafts. The rotational-lateral shimmy vibrations can occur during takeoff, taxiing, and landing and needs to be sufficiently controlled to avoid escalation and catastrophic failure of the landing gear system. Existing solutions for shimmy problem are largely passive control strategies known as shimmy dampers. Despite numerous studies on the source of shimmy and its trends, investigations on the design and performance analysis of shimmy dampers are scarce. From a design perspective, it is crucial to quantify the effective stiffness and damping supplied by the shimmy damper to the system in different operation states. Furthermore, the sensitivity of the damper performance to its design parameters needs to be thoroughly investigated in order to optimize the design for a particular aircraft. In this study, core relationships for three shimmy dampers are presented and used to perform sensitivity studies. These dampers are concepts by Boeing, Collins Aerospace (formerly UTAS), and a new one designated as the Symmetric Torque Link Damper (STLD). The influence of design parameters on the dampers’ performance is studied and observed trends are discussed in the light of inherent trade-offs. Subsequently, a nonlinear Multibody Dynamic model of the landing gear is utilized to obtain sample time histories of oscillations for each shimmy damper in order to highlight the performance differences and to demonstrate the influence of design parameters. Directions for designing future shimmy dampers and recommendations for optimizing them are offered.

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