• Title/Summary/Keyword: Speed profile optimization

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Design of Wheel Profile to Reduce Wear of Railway Wheel (곡선부에서 차륜 마모 저감을 위한 차륜답면 형상 설계)

  • Choi, Ha-Young;Lee, Dong-Hyong;Song, Chang-Yong;Lee, Jong-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.6
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    • pp.607-612
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    • 2012
  • The wear problem of wheel flange occurs at sharp curves of rail. This paper proposes a procedure for optimum design of a wheel profile wherein flange wear is reduced by improving an interaction between wheel and rail. Application of optimization method to design problem mainly depends on characteristics of design space. This paper compared local optimization method with global optimization according to sensitivity value of objective function for design variables to find out which optimization method is appropriable to minimize wear of wheel flange. Wheel profile is created by a piecewise cubic Hermite interpolating polynomial and dynamic performances are analyzed by a railway dynamic analysis program, VAMPIRE. From the optimization results, it is verified that the global optimization method such as genetic algorithm is more suitable to wheel profile optimization than the local optimization of SQP (Sequential Quadratic Programming) in case of considering the lack of empirical knowledge for initial design value.

Design of Railway Vehicle Wheel Profile Suitable for Dual-rail Profile (듀얼 레일 형상에 적합한 철도차량의 차륜 형상 설계)

  • Byon, Sung-Kwang;Lee, Dong-Hyeong;Choi, Ha-Young
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.3
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    • pp.30-37
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    • 2017
  • When a wheel profile of a train-tram is designed, both train and tram tracks should be considered. This study designed a wheel profile that enables high-speed driving(200km/h) on the train track and low speed driving on the tram track with multiple sharp curves. The study used the approximation optimization method to reduce cost and time, used the sequential quadratic programming method as the optimized algorithm, and the central composite design and response surface method as an approximate model. The optimized wheel shape based on this approximation optimization method reduced wear of the initial wheel showed a better performance in terms of derailment and lateral force.

Optimal Design Methodology of Automotive Tire Profile (자동차용 타이어 단면형상의 최적설계 방법론)

  • Hwang, Jun;Namgung, Seok
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.896-900
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    • 1996
  • New approach to determine the optimal design of automotive tire profile was introduced. In this study, optimal design technology was combined with a finite element method. Through tire profile optimization, tire profile was obtained and its profile improved high speed durability and maneuverability Static and dynamic behavior analysis of new concepted tire was compared with conventional tire profile. Optimal design methodology will provide much informations to improve various tire performances.

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Acceleration Optimization of a High-speed LCD Transfer Crane Using Finite Jerk (고속 LCD 이송 시스템의 진동감소를 위한 Finite Jerk 적용 가속도 최적화)

  • Song Tae-Jin;Hong Dae-Sun;Kim Ho-Jong;Bang Duck-Je;Chung Won-Jee
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.3 s.180
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    • pp.110-117
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    • 2006
  • This paper presents the acceleration optimization of a high-speed LCD (Liquid Crystal Display) transfer system for the minimization of vibration. To reduce vibration is one of key requirements for the dynamic control of a high-speed LCD transfer system. In this paper, the concept of finite jerk (the first derivative of acceleration) has been introduced for realizing input acceleration. The profile of finite jerk has been optimized using a genetic algorithm so that vibration effect can be minimized. In order to incorporate a genetic algorithm, the dynamic model of a LCD transfer system which is realized by using the ADAMS software has been linked to the simulation system constructed by the MATLAB. The simulation results illustrated that the duration of finite jerk can be optimized so as to minimize the magnitude of vibration. It has been also shown that the acceleration optimization with finite jerk can make the high-speed motion of a LCD transfer system result in low vibration, compared with the conventional motion control with trapezoidal velocity profile.

Multiple Drones Collision Avoidance in Path Segment Using Speed Profile Optimization (다수 드론의 충돌 회피를 위한 경로점 구간 속도 프로파일 최적화)

  • Kim, Tae-Hyoung;Kang, Tae Young;Lee, Jin-Gyu;Kim, Jong-Han;Ryoo, Chang-Kyung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.11
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    • pp.763-770
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    • 2022
  • In an environment where multiple drones are operated, collisions can occur when path points overlap, and collision avoidance in preparation for this is essential. When multiple drones perform multiple tasks, it is not appropriate to use a method to generate a collision-avoiding path in the path planning phase because the path of the drone is complex and there are too many collision prediction points. In this paper, we generate a path through a commonly used path generation algorithm and propose a collision avoidance method using speed profile optimization from that path segment. The safe distance between drones was considered at the expected point of collision between paths of drones, and it was designed to assign a speed profile to the path segment. The optimization problem was defined by setting the distance between drones as variables in the flight time equation. We constructed the constraints through linearize and convexification, and compared the computation time of SQP and convex optimization method in multiple drone operating environments. Finally, we confirmed whether the results of performing convex optimization in the 20 drone operating environments were suitable for the multiple drone operating system proposed in this study.

A Study on the Feed Rate Optimization of a Linear Motored Feed Drive System for Minimum Vibrations (Linear Motor 이송계의 진동 최소화를 위한 이송속도 최적화)

  • 최영휴;홍진현;최응영;김태형;최원선
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.321-325
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    • 2004
  • Linear motor feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modem machine tools require high speed and high precision feed drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a linear motor, for its minimum vibrations. Firstly, a 4-degree-of-freedom lumped parameter model is proposed for the vibration analysis of a linear motor driven machine tool feed drive system. Next, a feed rate optimization of the feed slide is carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile with jerk continuity. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

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A Study on the Feed Rate Optimization of a Ball Screw Feed Drive System for Minimum Vibrations (볼스크류 이송계의 진동 최소화를 위한 이송속도 최적화)

  • Choi, Young-Hyu;Hong, Jin-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.962-966
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    • 2004
  • Ball screw feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modern machine tools require high speed and high precision and drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slide system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a ball screw, for its minimum vibrations. Firstly, a 6-degree-of-freedom lumped parameter model was proposed for the vibration analysis of a ball screw driven machine tool feed drive system. Next, a feed rate optimization of the feed slide was carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile having finite jerk. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

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Design Method of Railway Wheel Profile with Objective Function of Eqivalent Conicity (등가답면구배를 목적함수로 하는 차륜답면형상 설계기법)

  • Hur, Hyun-Moo;You, Won-Hee;Park, Joon-Hyuk;Kim, Min-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.8
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    • pp.13-19
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    • 2010
  • A design method of railway wheel profile with objective function of equivalent conicity considering wheel dimension constraint, two points contact problem between wheel and rail was proposed. New design method shows good results. New wheel profile generated from optimization process shows better dynamic performance compared with initial profile as the purpose of wheel profile design. And to verify the design method with testing the stability of new wheel profile, we conducted a critical speed test for new wheel profile using scale model applied scaling method of railway vehicle dynamics. The result of critical speed test show good agreement with that of numerical analysis. From the above results, it is seen that the design method with objective function of equivalent conicity is feasible and it could be applied to design new wheel profile efficiently.

Optimal Shape Deign of a High Speed Switched Reluctance Motor Vsing Fuzzy Set Theory (퍼지 이론을 이용한 고속 회전용 스위치드 리럭턴스 모터의 형상 최적 설계)

  • Choi, Chang-Hwan;Yoo, Jae-Sun;Park, Kyi-Hwan
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.49 no.10
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    • pp.659-664
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    • 2000
  • This paper presents a new design method for improving the torque performance of a switched reluctance motor (SRM) for high speed applications. The drawback of the conventional design method based on the overall static average torque maximization is that the torque control performance is degraded at high speed. On the other hand, the proposed method optimizes the torque profile by diving it into several regions so that it is suitable for high speed operation. This multi-objective optimization problem is solved by using a fuzzy optimization algorithm which incorporates a finite element method. The torque performance of the motor for various speed ranges is investigated and the optimally designed motor show a better performance at high speed.

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Energy Efficient Electric Vehicle Driving Optimization Method Satisfying Driving Time Constraint (제한 주행시간을 만족하는 에너지 효율적인 전기자동차 주행 최적화 기법)

  • Baek, Donkyu
    • Journal of Korea Society of Industrial Information Systems
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    • v.25 no.2
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    • pp.39-47
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    • 2020
  • This paper introduces a novel system-level framework that derives energy efficient electric vehicle (EV) driving speed profile to extend EV driving range without additional cost. This paper first implements an EV power train model considering forces acting on a driving vehicle and motor efficiency. Then, it derivate the minimum-energy driving speed profile for a given driving mission defined by the route. This framework first formulates an optimization problem and uses the dynamic programming algorithm with a weighting factor to derive a speed profile minimizing both of energy consumption and driving time. This paper introduces various weighting factor tracking methods to satisfy the driving time constraint. Simulation results show that runtime of the proposed scaling algorithm is 34% and 50% smaller than those of the binary search algorithm and greedy algorithm, respectively.