• 한국정밀공학회지
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• 제21권7호
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• pp.115-123
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• 2004

This paper deals with the gait optimization of via points on biped robot. ZMP(Zero Moment point) is the most important index in a biped robot's dynamic walking stability. To stable walking of a biped robot, leg's trajectory and a desired ZMP trajectory is required, balancing motion is solved by FDM(Finite Difference Method). In this paper, optimal index is defined to dynamically stable walking of a biped robot, and genetic algorithm is applied to optimize gait trajectory and balancing motion of a biped robot. By genetic algorithm, the index of walking parameter is efficiently optimized, and dynamic walking stability is verified by ZMP verification equation. Genetic algorithm is only applied to balancing motion, and is totally applied to whole trajectory. All of the suggested motions of biped robot are investigated by simulations and verified through the real implementation.

• Journal of Information Processing Systems
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• 제19권5호
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• pp.563-575
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• 2023

Trajectory planning is a key technology for unmanned aerial vehicles (UAVs) to achieve complex flight missions. In this paper, a terminal constraints conversion-based Gauss pseudospectral trajectory planning optimization method is proposed. Firstly, the UAV trajectory planning mathematical model is established with considering the boundary conditions and dynamic constraints of UAV. Then, a terminal constraint handling strategy is presented to tackle terminal constraints by introducing new penalty parameters so as to improve the performance index. Combined with Gauss-Legendre collocation discretization, the improved Gauss pseudospectral method is given in detail. Finally, simulation tests are carried out on a four-quadrotor UAV model with different terminal constraints to verify the performance of the proposed method. Test studies indicate that the proposed method performances well in handling complex terminal constraints and the improvements are efficient to obtain better performance indexes when compared with the traditional Gauss pseudospectral method.

• 한국컴퓨터그래픽스학회논문지
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• 제25권3호
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• pp.133-142
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• 2019

물리기반 캐릭터 애니메이션에서 궤적 최적화(trajectory optimization) 기법은 캐릭터 동작에 대한 시스템 동역학 모델(system dynamics model)에 기반하여 가까운 최적의 미래 상태를 예측하여 캐릭터의 동작을 자동적으로 생성하는데 널리 사용되어 왔다. 캐릭터와 환경 간의 접촉 현상을 강체 충돌로 다루는 경우 일반적으로 시스템 동역학 모델은 그 수식이 닫힌 형식(closed form)으로 유도되지 못하고 미분이 불가능하다. 따라서 최근까지 많은 연구자들이 접촉 완화(contact smoothing) 기법을 통해 시스템 동역학의 수치적 미분에 기반한 효율적인 궤적 최적화 기법을 발표해 왔다. 하지만 수치적 미분 정보는 분석적 미분과 달리 부정확하기 때문에 궤적 최적화의 안정성에 영향을 미칠 수 있다. 이 문제를 해결하기 위해 본 논문에서는 접촉 완화 모델에 대한 근사화를 통해 시스템 동역학을 분석적으로 미분하여 닫힌 형식의 도함수를 유도하고, 이를 기반으로 사용자의 온라인 입력에 따라 예제 데이터 없이 이족 캐릭터의 동작을 안정적으로 생성하는 예측 제어 기법(model predictive control (MPC))을 제안한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.361-364
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• 1997

The re-enty guidance design involves trajectory optimization, generation of a reference drag acceleration profile with the satisfaction of trajectory constraints. This reference drag acceleration profile can be considered as the reference trajectory. This paper proposes the atmospheric re-entry system which is composed of longitudinal, later and range control. This paper shows the a performance of a re-entry guidance and control system using feedback linearization control and predictive control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권11호
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• pp.4453-4468
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• 2015

This paper investigates optimization-based base station (BS) placement. An optimization model is defined and the BS placement problem is transformed to a lexicographical stratified programming (LSP) model for a given trajectory, according to different accuracy requirements. The feasible region for BS deployment is obtained from the positioning system requirement, which is also solved with signal coverage problem in BS placement. The LSP mathematical model is formulated with the average geometric dilution of precision (GDOP) as the criterion. To achieve an optimization solution, a tolerant factor based complete stratified series approach and grid searching method are utilized to obtain the possible optimal BS placement. Because of the LSP model utilization, the proposed algorithm has wider application scenarios with different accuracy requirements over different trajectory segments. Simulation results demonstrate that the proposed algorithm has better BS placement result than existing approaches for a given trajectory.

• Journal of Information Processing Systems
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• 제17권1호
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• pp.37-50
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• 2021

Query applications based on nested data, the most commonly used form of data representation on the web, especially precise query, is becoming more extensively used. MapReduce, a distributed architecture with parallel computing power, provides a good solution for big data processing. However, in practical application, query requests are usually concurrent, which causes bottlenecks in server processing. To solve this problem, this paper first combines a column storage structure and an inverted index to build index for nested data on MapReduce. On this basis, this paper puts forward an optimization strategy which combines query execution service tree and frequent sub-query trajectory to reduce the response time of frequent queries and further improve the efficiency of multi-user concurrent queries on large scale nested data. Experiments show that this method greatly improves the efficiency of nested data query.

• 한국항공우주학회지
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• 제37권6호
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• pp.519-526
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• 2009

본 논문에서는 커나드와 테일핀을 가진 지대지 유도미사일이 대기권을 비행할 때 최대 사거리를 갖기 위한 효율적인 외형 형상 최적화 기법 연구에 대하여 기술하였다. 이를 위하여 비행궤적 해석 기법과 최적화 기법을 연계하여 미사일의 사거리 증대를 위한 외형 형상 최적화 전산 프로그램 시스템을 구축하였다. 비행궤적 해석부분에서는 반실험적 기법을 이용한 공력해석프로그램인 Missile DATCOM을 직접 연결하여 운동방정식 계산에 필요한 공력계수들을 계산 시간 단계 마다 효율적으로 제공할 수 있게 하였고 최고점 이후의 활공비행 구간에서는 최대 양항비를 갖는 Trim 조건 계산 모듈을 첨가하여 활공비행전 영역에서 최대 양항비 상태에서 지속적으로 비행한다는 가정으로 계산 하였다. 최적화 기법으로는 Response Surface Method(RSM)를 적용하여 계산 시간 효율화를 꾀하였다.

• International Journal of Control, Automation, and Systems
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• 제4권1호
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• pp.42-52
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• 2006

In order to utilize hydrodynamic drag force on articulated robots moving in an underwater environment, an optimum motion planning procedure is proposed. The drag force acting on cylindrical underwater arms is modeled and a directional drag measure is defined as a quantitative measure of reaction force in a specific direction in a workspace. A repetitive trajectory planning method is formulated from the general point-to-point trajectory planning method. In order to globally optimize the parameters of repetitive trajectories under inequality constraints, a 2-level optimization scheme is proposed, which adopts the genetic algorithm (GA) as the 1st level optimization and sequential quadratic programming (SQP) as the 2nd level optimization. To verify the validity of the proposed method, optimization examples of periodic motion planning with the simple two-link planner robot are also presented in this paper.

• Journal of applied mathematics & informatics
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• 제20권1_2호
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• pp.391-399
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• 2006

In order to solve the optimization problem of designing the trajectory of three-dimensional horizontal well, we establish a multi-phase, nonlinear, stochastic dynamic system of the trajectory of horizontal well. We take the precision of hitting target and the total length of the trajectory as the performance index. By the integration of the state equation, this model can be transformed into a nonlinear stochastic programming. We discuss here the necessary conditions under which a local solution exists and depends in a continuous way on the parameter (perturbation). According to the properties we propose a revised Hooke-Jeeves algorithm and work out corresponding software to calculate the local solution of the nonlinear stochastic programming and the expectancy of the performance index. The numerical results illustrate the validity of the proposed model and algorithm.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.528-532
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• 2017

The Theo Jansen mechanism using 1 degree of freedom is special system of walking robot. The trajectory made by the point of ground position is similar to other walking robot using many degrees of freedom. Because of diversity of design parameter of the Jansen mechanism, it makes a lot of trajectory and takes possibilities of optimization. However this research doesn't focus on the optimization of trajectory, but it focused on comprehensive design of the robot using well-known trajectory and line tracer logic to go fast and accurate along the line. The logic to follow a line has many kinds of possibility of algorithm. To eliminate uncertainty about recognizing a line, I divide the case of line following situation and make optimized logic.