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    ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๊ณผ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ์„ ๋™์‹œ์— ๊ณ ๋ คํ•œ ๊ธฐ๊ตฌ ์œ„์ƒ ๋ฐ ํ˜•์ƒ ํ†ตํ•ฉ ์ตœ์ ์„ค๊ณ„

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    ํ•™์œ„๋…ผ๋ฌธ (๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› : ๊ณต๊ณผ๋Œ€ํ•™ ๊ธฐ๊ณ„ํ•ญ๊ณต๊ณตํ•™๋ถ€(๋ฉ€ํ‹ฐ์Šค์ผ€์ผ ๊ธฐ๊ณ„์„ค๊ณ„์ „๊ณต), 2020. 8. ๊น€์œค์˜.Mechanism synthesis based on topology optimization has recently received much attention as an efficient design approach. The main thrust behind this trend is the capability of this method to determine automatically the topology and dimensions of linkage mechanisms. Towards this direction, there have been many investigations, but they have thus far focused mainly on mechanism synthesis considering kinematic characteristics describing a desired path or motion. Here, we propose a new topology optimization method that synthesizes a linkage mechanism considering not only kinematic but also compliance (K&C) characteristics simultaneously, as compliance characteristics can also significantly affect the linkage mechanism performance; compliance characteristics dictate how elastic components, such as bushings in a vehicle suspension, are deformed by external forces. To achieve our objective, we use the spring-connected rigid block model (SBM) developed earlier for mechanism synthesis considering only kinematic characteristics, but we make it suitable for the simultaneous consideration of K&C characteristics during mechanism synthesis by making its zero-length springs multifunctional. Variable-stiffness springs were used to identify the mechanism kinematic configuration only, but now in the proposed approach, they serve to determine not only the mechanism kinematic configuration but also the compliance element distribution. In particular, the ground-anchoring springs used to anchor a linkage mechanism to the ground are functionalized to simulate actual bushings as well as to identify the desired linkage kinematic chain. After the proposed formulation and numerical implementation are presented, three case studies to synthesize planar linkage mechanisms were considered. Through these case studies, we verified the validation of the proposed approach and proved that the proposed methodology could solve problems when existing methods could not. After the effectiveness of the proposed method is demonstrated with a simplified two-dimensional vehicle suspension design problem, the proposed methodology is applied to design a three-dimensional suspension. To deal with three-dimensional mechanisms, a spatial SBM is newly developed because only planar SBMs have been developed. Furthermore, a set of design variables which can vary bushing stiffness are newly introduced. Using the proposed method, it was possible to successfully synthesize two types of suspension mechanisms which have similar kinematic characteristics to each other but different compliance characteristics. By using the proposed method simultaneously considering kinematic and compliance characteristics, a unique suspension mechanism having an integral module which is known to improve R&H performances was synthesized. In this study, although applications were made only to the design of vehicle suspensions, other practical design problems for which K&C characteristics must be considered simultaneously can be also effectively solved by the proposed approach. This study is expected to pave the way to advance the topology optimization method for general linkage mechanisms considering kinematic characteristics but also the other characteristics such as force-related characteristics.์œ„์ƒ ์ตœ์ ํ™”(topology optimization) ๊ธฐ๋ฒ•์„ ์ด์šฉํ•œ ํ•œ ๊ธฐ๊ตฌ ํ•ฉ์„ฑ(mechanism synthesis)์€ ๊ทธ ํšจ์œจ์„ฑ์œผ๋กœ ์ธํ•ด ์ตœ๊ทผ ๋งŽ์€ ์ฃผ๋ชฉ์„ ๋ฐ›๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์ถ”์„ธ์˜ ์ฃผ ์›์ธ์€ ๊ธฐ๊ตฌ ์œ„์ƒ ์ตœ์ ํ™” ๊ธฐ๋ฒ•์œผ๋กœ ์ธํ•ด ๊ธฐ๊ตฌ์˜ ์œ„์ƒ(topology)๊ณผ ์น˜์ˆ˜(dimension)๋ฅผ ์ž๋™์œผ๋กœ ํ•ฉ์„ฑํ•  ์ˆ˜ ์žˆ๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ์ด๋Ÿฌํ•œ ๋ฐฉํ–ฅ์„ฑ์„ ๊ฐ€์ง€๊ณ  ์ง€๊ธˆ๊นŒ์ง€ ๋งŽ์€ ์—ฐ๊ตฌ๋“ค์ด ์ง„ํ–‰๋˜์–ด ์™”์ง€๋งŒ, ์ง€๊ธˆ๊นŒ์ง€ ์ง„ํ–‰๋œ ์—ฐ๊ตฌ๋“ค์€ ๋ชจ๋‘ ๊ฒฝ๋กœ ํ•ฉ์„ฑ์ด๋‚˜ ์šด๋™ ํ•ฉ์„ฑ๊ณผ ๊ฐ™์ด ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ์„ ๊ณ ๋ คํ•˜๋Š” ๋ฐ์—๋งŒ ๊ด€์‹ฌ์ด ์ง‘์ค‘๋˜์—ˆ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ธฐ๊ตฌ์˜ ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ(kinematic characteristics)๊ณผ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ(compliance characteristics)์„ ๋™์‹œ์— ๊ณ ๋ คํ•  ์ˆ˜ ์žˆ๋Š” ์ƒˆ๋กœ์šด ๊ธฐ๊ตฌ ์œ„์ƒ ์ตœ์ ํ™” ๊ธฐ๋ฒ•์„ ์ œ์•ˆํ•œ๋‹ค. ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ์€ ๊ธฐ๊ตฌ ์„ค๊ณ„์— ์žˆ์–ด ๋งค์šฐ ์ค‘์š”ํ•œ ํŠน์„ฑ์ด์ง€๋งŒ, ์™ธ๋ ฅ์ด ์ž‘์šฉํ•˜์˜€์„ ๋•Œ ์ž๋™์ฐจ ์„œ์ŠคํŽœ์…˜(vehicle suspension)์˜ ๋ถ€์‹ฑ(bushing)๊ณผ ๊ฐ™์€ ํƒ„์„ฑ ์š”์†Œ๋“ค์˜ ๋ณ€ํ˜•์œผ๋กœ ์ธํ•ด ๋‚˜ํƒ€๋‚˜๋Š” ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ ๋˜ํ•œ ๊ธฐ๊ตฌ ์„ค๊ณ„ ์‹œ ๊ณ ๋ คํ•ด์•ผ ํ•  ์ค‘์š”ํ•œ ํŠน์„ฑ์ด๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ์ƒˆ๋กœ์šด ๊ธฐ๊ตฌ ์œ„์ƒ ์ตœ์ ํ™” ๊ธฐ๋ฒ•์„ ์œ„ํ•ด ์šฐ๋ฆฌ๋Š” ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๋งŒ์„ ๊ณ ๋ คํ•˜๊ธฐ ์œ„ํ•ด ๊ฐœ๋ฐœ๋˜์—ˆ๋˜ ์Šคํ”„๋ง-์—ฐ๊ฒฐ ๋ธ”๋ก ๋ชจ๋ธ(spring-connected block model)์„ ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๊ณผ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ์„ ๋™์‹œ์— ๊ณ ๋ คํ•  ์ˆ˜ ์žˆ๋„๋ก ๊ณ ์•ˆํ•˜์˜€๋‹ค. ๊ธฐ์กด์˜ ์Šคํ”„๋ง-์—ฐ๊ฒฐ ๋ธ”๋ก ๋ชจ๋ธ์—์„œ๋Š” ๊ธฐ๊ตฌํ•™์  ์—ฐ๊ฒฐ ๊ด€๊ณ„๋งŒ์„ ํ‘œํ˜„ํ•˜๋Š”๋ฐ ์‚ฌ์šฉ๋˜๋˜ ๊ฐ€๋ณ€ ๊ฐ•์„ฑ ์Šคํ”„๋ง์„ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ธฐ๊ตฌํ•™์  ์—ฐ๊ฒฐ ๊ด€๊ณ„๋ฟ ์•„๋‹ˆ๋ผ ์‹ค์ œ ๋ถ€์‹ฑ์„ ํ‘œํ˜„ํ•˜๋„๋ก ๋‹ค๋ชฉ์ ์œผ๋กœ ํ™œ์šฉํ•˜์—ฌ ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๊ณผ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ์„ ํ•˜๋‚˜์˜ ๋ชจ๋ธ๋ง์„ ํ†ตํ•ด ์„ฑ๊ณต์ ์œผ๋กœ ํ‘œํ˜„ํ•˜์˜€๋‹ค. ๊ฐœ๋ฐœํ•œ ๋ฐฉ๋ฒ•๋ก ์˜ ํšจ๊ณผ๋ฅผ ์ž…์ฆํ•˜๊ธฐ ์œ„ํ•ด ํ‰๋ฉด ๊ธฐ๊ตฌ ํ•ฉ์„ฑ์„ ๋ชฉํ‘œ๋กœ ํ•œ ์„ธ ์ข…๋ฅ˜์˜ ์‚ฌ๋ก€ ์—ฐ๊ตฌ(case study)๋ฅผ ์ง„ํ–‰ํ•˜์˜€๊ณ , ์ด๋Ÿฌํ•œ ์‚ฌ๋ก€ ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ์šฐ๋ฆฌ๋Š” ์ œ์•ˆํ•œ ๋ฐฉ๋ฒ•์ด ๊ธฐ์กด์˜ ๋ฐฉ๋ฒ•์œผ๋กœ๋Š” ํ•ด๊ฒฐํ•  ์ˆ˜ ์—†๋Š” ๋ฌธ์ œ ์ƒํ™ฉ์„ ํ•ด๊ฒฐํ•  ์ˆ˜ ์žˆ์Œ์„ ํ™•์ธํ•˜์˜€๋‹ค. ๊ฐœ๋ฐœํ•œ ๋ฐฉ๋ฒ•๋ก ์„ ๋ณด๋‹ค ์‹ค์šฉ์ ์ธ ๋ฌธ์ œ์— ์ ์šฉํ•˜๊ธฐ ์œ„ํ•ด 3์ฐจ์› ์ž๋™์ฐจ ์„œ์ŠคํŽœ์…˜(vehicle suspension) ์„ค๊ณ„ ํ•˜๊ณ ์ž ํ•˜์˜€์œผ๋ฉฐ, ์ด๋ฅผ ์œ„ํ•ด ์Šคํ”„๋ง-์—ฐ๊ฒฐ ๋ธ”๋ก ๋ชจ๋ธ์„ 3์ฐจ์›์œผ๋กœ ํ™•์žฅํ•˜์˜€๋‹ค. ๋˜ํ•œ, ๋ณด๋‹ค ์‹ค์šฉ์ ์ธ ์„ค๊ณ„ ๊ฒฐ๊ณผ ๋„์ถœ์„ ์œ„ํ•ด 2์ฐจ์› ์‚ฌ๋ก€ ์—ฐ๊ตฌ์—์„œ๋Š” ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜๋˜ ๋ถ€์‹ฑ ๊ฐ•์„ฑ ์กฐ์ ˆ ์„ค๊ณ„ ๋ณ€์ˆ˜๋ฅผ ์ถ”๊ฐ€์ ์œผ๋กœ ๋„์ž…ํ•˜์—ฌ, ๋ถ€์‹ฑ ๊ฐ•์„ฑ๋„ ๋™์‹œ์— ์„ค๊ณ„๋ฅผ ์ง„ํ–‰ํ•˜์˜€๋‹ค. 3์ฐจ์› ์„œ์ŠคํŽœ์…˜ ์„ค๊ณ„๋Š” ๊ธฐ๊ตฌํ•™์  ์กฐ๊ฑด์€ ๋™์ผํ•˜์ง€๋งŒ, ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ์€ ๋‹ค๋ฅธ ๋‘ ๊ฐ€์ง€ ์กฐ๊ฑด์— ๋Œ€ํ•ด ์ง„ํ–‰๋˜์—ˆ์œผ๋ฉฐ, ๋‘ ์„ค๊ณ„ ์กฐ๊ฑด์—์„œ ๋ชจ๋‘ ์„œ์ŠคํŽœ์…˜ ํ•ฉ์„ฑ์— ์„ฑ๊ณตํ•˜์˜€๋‹ค. ํŠนํžˆ, ๋‘ ์„œ์ŠคํŽœ์…˜์˜ ๊ฒฐ๊ณผ ์œ„์ƒ์ด ์„œ๋กœ ๋‹ค๋ฅธ ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ์—ˆ๋Š”๋ฐ, ์ด๋ฅผ ํ†ตํ•ด ๊ธฐ๊ตฌํ•™์  ์กฐ๊ฑด์€ ๋™์ผํ•˜๋˜ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ์กฐ๊ฑด์ด ๋‹ฌ๋ผ์ง€๋ฉด ๊ฒฐ๊ณผ ์œ„์ƒ์ด ๋‹ฌ๋ผ์งˆ ์ˆ˜ ์žˆ์Œ์„ ํ™•์ธํ•˜์˜€๊ณ , ๊ฐœ๋ฐœํ•œ ๋ฐฉ๋ฒ•๋ก ์„ ํ†ตํ•ด ์„ค๊ณ„ ์กฐ๊ฑด์— ๋งž๋Š” ๊ธฐ๊ตฌ์˜ ์œ„์ƒ๊ณผ ์น˜์ˆ˜ ๊ทธ๋ฆฌ๊ณ  ํ•„์š”ํ•œ ๋ถ€์‹ฑ ๊ฐ•์„ฑ๊นŒ์ง€๋„ ์„ฑ๊ณต์ ์œผ๋กœ ์„ค๊ณ„ํ•  ์ˆ˜ ์žˆ์Œ์„ ์ฆ๋ช…ํ•˜์˜€๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋Š” ์ปดํ”Œ๋ผ์ด์–ธ์Šค ์กฐ๊ฑด์ด ํŠนํžˆ ์ค‘์š”์‹œ ๋˜๋Š” ์ž๋™์ฐจ ์„œ์ŠคํŽœ์…˜์„ ์„ค๊ณ„ํ•˜๋Š”๋ฐ ์ง‘์ค‘ํ•˜์˜€์ง€๋งŒ, ๊ฐœ๋ฐœํ•œ ๋ฐฉ๋ฒ•๋ก ์€ ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๊ณผ ์ปดํ”Œ๋ผ์ด์–ธ์Šค ํŠน์„ฑ์ด ๋ชจ๋‘ ์š”๊ตฌ๋˜๋Š” ๋‹ค๋ฅธ ์„ค๊ณ„ ๋ฌธ์ œ์—๋„ ์ ์šฉ๋  ์ˆ˜ ์žˆ์„ ๊ฒƒ์œผ๋กœ ๊ธฐ๋Œ€๋œ๋‹ค. ๋˜ํ•œ, ์ด ์—ฐ๊ตฌ๋Š” ๊ธฐ๊ตฌํ•™์  ํŠน์„ฑ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ํž˜๊ณผ ๊ด€๋ จ๋œ ๋‹ค๋ฅธ ํŠน์„ฑ์„ ๊ณ ๋ คํ•œ ์ผ๋ฐ˜์ ์ธ ๊ธฐ๊ตฌ ์œ„์ƒ ์ตœ์ ํ™” ๊ธฐ๋ฒ•์œผ๋กœ์˜ ๋ฐœ์ „์— ๊ธฐ์—ฌํ•  ๊ฒƒ์œผ๋กœ ๊ธฐ๋Œ€๋œ๋‹ค.CHAPTER 1. Introduction 1 1.1 Motivation and related literatures 1 1.2 Research objectives 6 1.3 Background research 8 1.3.1 Linkage mechanism synthesis based on the spring-connected rigid block model (SBM) 8 1.3.2 Determination of the systems degree-of-freedom (DOF) based on the work transmittance efficiency function 10 1.4 Outline of thesis 12 CHAPTER 2. Unified topology and shape optimization method for the mechanism synthesis simultaneously considering kinematic and compliance (K&C) characteristics 18 2.1 Overview 18 2.2 Modeling and analysis 23 2.2.1 Modeling 23 2.2.2 Kinematic and compliance analyses with the SBM 26 2.3 Optimization Formulation 33 2.3.1 Design variable and interpolation 33 2.3.2 Objective and constraint functions 35 2.3.3 Sensitivity analysis 39 2.4 Case studies 43 2.4.1 Case study 1 - Validation of the proposed method 43 2.4.2 Case study 2 - Demonstration of the advantage of the proposed method 46 2.4.3 Case study 3 - Application to the design of a 2D vehicle suspension 50 2.5 Summary 57 CHAPTER 3. Design of vehicle suspensions for rear using topology optimization method considering K&C characteristics 78 3.1 Overview 78 3.2 Modeling and analysis based on the spatial SBM 81 3.2.1 The spatial SBM for the design of a vehicle suspension 81 3.2.2 Kinematic and compliance analyses by the spatial SBM 83 3.3 Optimization Formulation 90 3.3.1 Design variable and interpolation 90 3.3.2 Objective and constraint functions 93 3.3.3 Sensitivity analysis 95 3.4 Design of vehicle suspensions for rear using the proposed method 99 3.4.1 Definition of problem 99 3.4.2 Design Case 1 - Recovery of a double wishbone suspension 101 3.4.3 Design Case 2 - Suspension synthesis for improving ride and handling (R&H) performances 104 3.5 Summary 110 CHAPTER 4. Conclusions 133 APPENDIX A. Target cascading process for deriving K&C characteristics of a suspension to improve vehicles R&H performances 138 A.1 Overview 138 A.2 Ride and handling (R&H) performances 139 A.3 Analysis procedure to evaluate R&H performances using a double wishbone suspension 140 A.4 Design optimization of a double wishbone suspension for deriving K&C characteristics to improve R&H performances 141 A.4.1 Design variable and interpolation 141 A.4.2 Metamodeling 142 A.4.3 Optimization formulation 144 A.4.4 Optimization result 145 APPENDIX B. Technique to suppress floating blocks 158 B.1 Overview 158 B.2 Explanation of techniques to suppress floating blocks 159 B.3 Revisit Case study 3 for applying the technique to suppress floating blocks 161 APPENDIX C. Investigation of mesh dependency issue 167 C.1 Overview 167 C.2 Re-consideration of Case study 1 with the more number of rigid blocks 168 REFERENCES 172 ABSTRACT (KOREAN) 181 ACKNOWLEDTEMENTS 184Docto

    Kinematics and Robot Design IV, KaRD2021

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    This volume collects the papers published on the special issue โ€œKinematics and Robot Design IV, KaRD2021โ€ (https://www.mdpi.com/journal/robotics/special_issues/KaRD2021), which is the forth edition of the KaRD special-issue series, hosted by the open-access journal โ€œMDPI Roboticsโ€. KaRD series is an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on โ€œmechanisms and roboticsโ€. KaRD2021, after the peer-review process, accepted 12 papers. The accepted papers cover some theoretical and many design/applicative aspects

    ๊ธฐ๊ตฌ ์œ„์ƒ ๋ฐ ์น˜์ˆ˜ ํ†ตํ•ฉ ํ•ฉ์„ฑ ๊ธฐ๋ฒ• ๊ฐœ๋ฐœ๊ณผ ์ด๋ฅผ ์‘์šฉํ•œ ์ฐจ๋Ÿ‰ ํ˜„๊ฐ€ ์žฅ์น˜ ๊ฐœ๋…์„ค๊ณ„

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    ํ•™์œ„๋…ผ๋ฌธ (๋ฐ•์‚ฌ)-- ์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› ๊ณต๊ณผ๋Œ€ํ•™ ๊ธฐ๊ณ„ํ•ญ๊ณต๊ณตํ•™๋ถ€, 2017. 8. ๊น€์œค์˜.Topology optimization of rigid-link mechanisms, a methodology for obtaining linkages that satisfy a set of user defined kinematic requirements without any a priori baseline design, is a new paradigm that can be usefully employed in industries such as automotive or aerospace engineering. In previous research, however, the methodology has been limited to simple planar linkages. In this research, a new formulation for synthesizing the topology and dimension of linkages is proposed. To design topology of link mechanisms by using the optimization method, a formulation which represents the DOF (Degree-of-Freedom) in differentiable form has to be considered. Herein, the DOF is the minimum number of actuators that is required to decide the position of the all link components. In previous research, motion compliance and load stiffness have been employed to avoid deficient-DOF state and redundant-DOF state, respectively. To this end, the motion compliance is the system flexibility under displacement excitation such as motion drive, and the load stiffness is the system rigidity under force excitation such as external resistance forces. However, in aspect of the multi-objective optimization, implementation of the DOF control by using the two functions, the motion compliance and load stiffness, contradictive to each other is quite particular about heuristic weighting factor decision issue. Meanwhile, as the work transmittance efficiency function suggested in this thesis is exploited to control the system DOF, there is no issue related to the preference decision between two objective functions. That is, only a unified objective function is used to avoid the deficient- and the redundant-DOF states. Therefore, it is possible to design complicated systems, unlike the previous research which is hard to consider it due to difficulties of the DOF control. Our approach is validated through several case studies. In the planar design case, benchmark type four-bar linkages and automotive steering systems are considered. For spatial linkage synthesis problems, automotive suspension mechanisms are designed by the suggested method. To find a better solution in suspension design, we employed a simultaneous topology and shape optimization method. As a result, a new type suspension mechanism is obtained by the unified topology and dimension synthesis method, especially when a smaller design space compared with nominal one is provided. To analyze the behavior of the newly designed suspension system, the screw-axis theory is applied. From this investigation, it is found that a new special module is included in the new-concept suspension and it works as a conventional link component. In this research, according to this property of the newly proposed concept, it will be called a hidden link suspension. It is also shown that the suspension installation space can be reduced compared with nominal multi-link type suspensions by exploiting the hidden link module. The synthesized suspension mechanism is the first successful industrial result obtained by the unified topology and dimension synthesis method. Especially, the proposed method can provide new insight to engineers who want to enhance the product quality by making use of totally different conceptual designs as shown in this research. In the near future, it will be possible to apply the suggested linkage synthesis method to other practical problems, beyond the automotive industry problems, to find more advanced mechanisms.1. INTRODUCTION 1 1.1 Motivation: review of conventional synthesis methods 3 1.2 Previous researches for unified synthesis of mechanisms 10 1.3 Main contributions of this thesis 20 2. TOPOLOGY OPTIMIZATION METHOD FOR LINKAGE MECHANISMS 25 2.1 Definition of problem 27 2.2 Modeling, analysis, and formulation 32 2.2.1 Modeling and Analysis 32 2.2.2 Objective function 37 2.3 Mechanism synthesis by the proposed formulation 46 2.3.1 Synthesis of Grashof-type four-bar linkage mechanisms 46 2.3.2 Synthesis of steering linkage mechanisms 50 2.4 Post-processing 56 2.4.1 Step 1: Binarizing 56 2.4.2 Step 2: Pruning 56 2.4.3 Step 3: Simplification 57 2.5 Summary 62 3. SPATIAL VEHICLE SUSPENSION DESIGN BY USING SIMULTANEOUS TOPOLOGY AND SHAPE OPTIMIZATION 85 3.1 Review of recently developed suspension design methods 87 3.2 Ground structure model and kinematic analysis 90 3.2.1 Spatial ground structure composed of bars and springs 90 3.2.2 Nonlinear finite element analysis of spatial bar elements 92 3.2.3 Rigid-body motion and constraint of the hub-carrier 97 3.2.4 Governing equations for kinematic analysis 101 3.3 Optimization based formulation for mechanism synthesis 104 3.3.1 Design variables and interpolation 104 3.3.2 Work transmittance efficiency based formulation 106 3.3.3 Design sensitivity analysis for design optimization 112 3.4 Suspension mechanism synthesis by the proposed method 114 3.4.1 Recovery of double wishbone and multilink suspensions 114 3.4.2 Synthesis of suspensions satisfying R&H requirements 119 3.4.3 Interpretation of the optimized suspension layouts 126 3.5 Summary 132 4. NEW CONCEPT SUSPENSION INCLUDING HIDDEN LINK MODULE 145 4.1 Overview 145 4.2 A new concept obtained from topology optimization 147 4.2.1 A special module included in the new concept 147 4.2.2 Strategy for interpretation of the special module 149 4.3 Force transmission analysis 152 4.3.1 Introduction of the screw axis theory 153 4.3.2 Force transmission analysis of the RSR-limb 159 4.3.3 Suggestion of hidden link concept 164 4.3.4 Validation of the hidden link concept 166 4.4 Nonlinear effects of the hidden link suspension 174 4.4.1 Effective length of the hidden link in nonlinear motion 176 4.4.2 Prediction of the effective length of the hidden link 181 4.4.3 Design guide line of the hidden link suspension 186 4.5 Summary 192 5. CONCLUSIONS 211 APPENDIX A REMEDIES FOR THE MESH DEPENDENCY ISSUE 216 A.1 Overview 216 A.2 Coarse-to-fine mesh converting approach 218 A.3 Simultaneous topology and shape optimization approach 222 APPENDIX B WRENCH SCREW ANALYSIS 231 B.1 Overview 231 B.2 Wrench screw of arm component 232 B.3 Wrench screw of RSR limb module 237 APPENDIX C VIRTUAL PRODUCT DEVELOPMENT FOR VALIDATION OF HIDDEN LINK CONCEPT 242 C.1 Overview 242 C.2 Virtual Product development process 243 REFERENCES 248 ABSTRACT (KOREAN) 259 ACKNOWLEDGEMENTS 262Docto

    Compendium in Vehicle Motion Engineering

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    This compendium is written for the course โ€œMMF062 Vehicle Motion Engineeringโ€ at Chalmers University of Technology. The compendium covers more than included in that course; both in terms of subsystem designs and in terms of some teasers for more advanced studies of vehicle dynamics. Therefore, it is also useful for the more advanced course โ€œTME102 Vehicle Modelling and Controlโ€.The overall objective of the compendium is to educate vehicle dynamists, i.e., engineers that understand and can contribute to development of good motion and energy functionality of vehicles. The compendium focuses on road vehicles, primarily passenger cars and commercial vehicles. Smaller road vehicles, such as bicycles and single-person cars, are only very briefly addressed. It should be mentioned that there exist a lot of ground-vehicle types not covered at all, such as: off-road/construction vehicles, tracked vehicles, horse wagons, hovercrafts, or railway vehicles.Functions are needed for requirement setting, design and verification. The overall order within the compendium is that models/methods/tools needed to understand each function are placed before the functions. Chapters 3-5 describes (complete vehicle) โ€œfunctionsโ€, organised after vehicle motion directions:\ub7\ua0\ua0\ua0\ua0\ua0\ua0\ua0\ua0 Chapter 3:\ua0Longitudinal\ua0dynamics\ub7\ua0\ua0\ua0\ua0\ua0\ua0\ua0\ua0 Chapter 4:\ua0Lateral\ua0dynamics\ub7\ua0\ua0\ua0\ua0\ua0\ua0\ua0\ua0 Chapter 5:\ua0Vertical\ua0dynamicsChapter 1 introduces automotive industry and the overall way of working there and defines required pre-knowledge from โ€œproduct-genericโ€ engineering, e.g. modelling of dynamic systems.Chapter 2 also describes the subsystems relevant for vehicle dynamics:โ€ข Wheels and Tyre\ua0โ€ข Suspension\ua0โ€ข Propulsion\ua0โ€ข Braking System\ua0โ€ข Steering System\ua0โ€ข Environment Sensing Syste

    Optimisation of racing car suspensions featuring inerters

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    Racing car suspensions are a critical system in the overall performance of the vehicle. They must be able to accurately control ride dynamics as well as influencing the handling characteristics of the vehicle and providing stability under the action of external forces. This work is a research study on the design and optimisation of high performance vehicle suspensions using inerters. The starting point is a theoretical investigation of the dynamics of a system fitted with an ideal inerter. This sets the foundation for developing a more complex and novel vehicle suspension model incorporating real inerters. The accuracy and predictability of this model has been assessed and validated against experimental data from 4- post rig testing. In order to maximise overall vehicle performance, a race car suspension must meet a large number of conflicting objectives. Hence, suspension design and optimisation is a complex task where a compromised solution among a set of objectives needs to be adopted. The first task in this process is to define a set of performance based objective functions. The approach taken was to relate the ride dynamic behaviour of the suspension to the overall performance of the race car. The second task of the optimisation process is to develop an efficient and robust optimisation methodology. To address this, a multi-stage optimisation algorithm has been developed. The algorithm is based on two stages, a hybrid surrogate model based multiobjective evolutionary algorithm to obtain a set of non-dominated optimal suspension solutions and a transient lap-time simulation tool to incorporate external factors to the decision process and provide a final optimal solution. A transient lap-time simulation tool has been developed. The minimum time manoeuvring problem has been defined as an Optimal Control problem. A novel solution method based on a multi-level algorithm and a closed-loop driver steering control has been proposed to find the optimal lap time. The results obtained suggest that performance gains can be obtained by incorporating inerters into the suspension system. The work suggests that the use of inerters provides the car with an optimised aerodynamic platform and the overall stability of the vehicle is improved

    Exploiting linkage information in real-valued optimization with the real-valued gene-pool optimal mixing evolutionary algorithm

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    The recently introduced Gene-pool Optimal Mixing Evolutionary Algorithm (GOMEA) has been shown to be among the state-of-the-art for solving discrete optimization problems. Key to the success of GOMEA is its ability to efficiently exploit the linkage structure of a problem. Here, we introduce the Real-Valued GOMEA (RV-GOMEA), which incorporates several aspects of the real-valued EDA known as AMaLGaM into GOMEA in order to make GOMEA well-suited for real-valued optimization. The key strength of GOMEA to competently exploit linkage structure is effectively preserved in RV-GOMEA, enabling excellent performance on problems that exhibit a linkage structure that is to some degree decomposable. Moreover, the main variation operator of GOMEA enables substantial improvements in performance if the problem allows for partial evaluations, which may be very well possible in many real-world applications. Comparisons of performance with state-of-the-art algorithms such as CMA-ES and AMaLGaM on a set of well-known benchmark problems show that RV-GOMEA achieves comparable, excellent scalability in case of black-box optimization. Moreover, RV-GOMEA achieves unprecedented scalability on problems that allow for partial evaluations, reaching near-optimal solutions for problems with up to millions of real-valued variables within one hour on a normal desktop computer

    Speeding-Up Expensive Evaluations in High-Level Synthesis Using Solution Modeling and Fitness Inheritance

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    High-Level Synthesis (HLS) is the process of developing digital circuits from behavioral specifications. It involves three interdependent and NP-complete optimization problems: (i) the operation scheduling, (ii) the resource allocation, and (iii) the controller synthesis. Evolutionary Algorithms have been already effectively applied to HLS to find good solution in presence of conflicting design objectives. In this paper, we present an evolutionary approach to HLS that extends previous works in three respects: (i) we exploit the NSGA-II, a multi-objective genetic algorithm, to fully automate the design space exploration without the need of any human intervention, (ii) we replace the expensive evaluation process of candidate solutions with a quite accurate regression model, and (iii) we reduce the number of evaluations with a fitness inheritance scheme. We tested our approach on several benchmark problems. Our results suggest that all the enhancements introduced improve the overall performance of the evolutionary search
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