• 제어로봇시스템학회논문지
• /
• 제15권6호
• /
• pp.573-580
• /
• 2009

In this paper, we develop a functional test model for magnetic bearing wheels. The functional test model is an electromagnetic levitation system that has three degree of freedom, which consists of one axial suspension from gravity and two axes gimbaling capability to small angels. A nonlinear controller with high-gain observers is proposed and the real-time experiment results show that the rotor is accurately levitated at the desired position and well-balanced, which is a suitable result for the potential use an magnetic bearing wheels. Also, the proposed scheme exhibits better performance when it is compared with the conventional PID control method.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제15권1호
• /
• pp.12-19
• /
• 2015

In order to guide the robots move along a collision-free path efficiently and reach the goal position quickly in the unknown multi-obstacle environment, this paper presented the navigation problem of a wheel mobile robot based on proximity sensors by fuzzy logic controller. Then a genetic algorithm was applied to optimize the membership function of input and output variables and the rule base of the fuzzy controller. Here the environment is unknown for the robot and contains various types of obstacles. The robot should detect the surrounding information by its own sensors only. For the special condition of path deadlock problem, a wall following method named angle compensation method was also developed here. The simulation results showed a good performance for navigation problem of mobile robots.

• ETRI Journal
• /
• 제30권6호
• /
• pp.774-782
• /
• 2008

An operational orbit determination (OD) and prediction system for the geostationary Communication, Ocean, and Meteorological Satellite (COMS) mission requires accurate satellite positioning knowledge to accomplish image navigation registration on the ground. Ranging and tracking data from a single ground station is used for COMS OD in normal operation. However, the orbital longitude of the COMS is so close to that of satellite tracking sites that geometric singularity affects observability. A method to solve the azimuth bias of a single station in singularity is to periodically apply an estimated azimuth bias using the ranging and tracking data of two stations. Velocity increments of a wheel off-loading maneuver which is performed twice a day are fixed by planned values without considering maneuver efficiency during OD. Using only single-station data with the correction of the azimuth bias, OD can achieve three-sigma position accuracy on the order of 1.5 km root-sum-square.

• 한국산업융합학회 논문집
• /
• 제18권2호
• /
• pp.67-74
• /
• 2015

Two-wheeled driying mobild robots are precise controlled in terms of linear contol methods without considering the nonlinear dynamical characteristics. However, in the high maneuvering situations such as fast turn and abrupt start and stop, such neglected terms become dominant and heavy influence the overall driving performance. This study describes the nonlinear optimal control method to take advantage of the exact nonlinear dynamics of the balancing robot. Simulation results indicate that the optimal control outperforms in the respect of transient performance and required wheel torques. A design example is suggested for the state matrix that provides design flexibility in the control. It is shown that a well-planned state matrix by reflecting the physics of a balancing robot greatly conrtibutes to the driving performance and stability.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 추계학술대회논문집
• /
• pp.658-661
• /
• 2008

Vibrations transmitted through rolling tire are major sources of road noise in vehicle interior on the range of $0{\sim}500Hz$. Among various road noises, tire cavity noise makes many problems recently. Vehicle NVH performance has improved better and road surfaces are made well. But tires are changed to high inches and low series. So tire cavity noise becomes more serious. In this paper, a designed material for reducing tire cavity noise is proposed. On the surface inside tire, this material is attached at one position using double-tape. This material disperses the pressure variations inside the tire. So a spindle forces at wheel center are reduced. And tire cavity noise at vehicle interior is also reduced. Durability is verified by tire only test and vehicle test. Noise performance also compared with peak levels after attaching this material.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1719_1720
• /
• 2009

Wheeled mobile robot has different mobility and steerability which determined by type of wheel and it's arrangement. Generally wheeled mobile robot's dynamics are nonlinear and various control methods have studied to control the mobile robot efficiently. In this paper, a T-S fuzzy modeling of a 2-wheeled mobile robot is mand a stable LMI-based state feedback fuzzy controller is designed and applied to the position control of the mobile robot for the reference trajectory following. Also, the verification of the designed controller is done by computer simulation.

• 한국자동차공학회논문집
• /
• 제11권3호
• /
• pp.214-219
• /
• 2003

This paper includes real-time tractive force estimation method using standard vehicle sensors such as wheel speed, brake pressure, throttle position, engine speed, and transmission carrier speed sensor. Engine map, torque converter lookup table, shaft torque observer, and brake gain adaptation method are used to estimate the tractive force. To verify this estimator, measurement which uses strain-based brake torque sensor and estimation results are presented. All results was performed using a real vehicle in a real-time.

• 로봇학회논문지
• /
• 제9권3호
• /
• pp.160-169
• /
• 2014

Odometry using wheel encoder is a common relative positioning technique for wheeled mobile robots. The major drawback of odometry is that the kinematic modeling errors are accumulated when the travel distance increases. Therefore, accurate calibration of odometry is required. In several related works, various schemes for odometry calibration are proposed. However, design guidelines of test tracks for odometry calibration were not considered. More accurate odometry calibration results can be achieved by using appropriate test track because the position and orientation errors after the test are affected by the test track. In this paper, we propose the design guidelines of test tracks for odometry calibration schemes using experimental heading errors. Numerical simulations and experiments clearly demonstrate that the proposed design guidelines result in more accurate calibration results.

• 제어로봇시스템학회논문지
• /
• 제15권10호
• /
• pp.1014-1020
• /
• 2009

This work deals with navigation of an omni-directional mobile robot with active caster wheels. Initially, the posture of the omni-directional mobile robot is calculated by using the odometry information. Next, the position accuracy of the mobile robot is measured through comparison of the odometry information and the external sensor measurement. Finally, for successful navigation of the mobile robot, a motion planning algorithm that employs kinematic redundancy resolution method is proposed. Through experiments for multiple obstacles and multiple moving obstacles, the feasibility of the proposed navigation algorithm was verified.

• 전자공학회논문지
• /
• 제51권2호
• /
• pp.190-196
• /
• 2014

본 논문에서는 밸런싱 로봇의 동역학적 모델의 해석으로부터 기울기와 조향이 독립되어 있어 서로 영향을 받지 않는 것을 증명하고, 다변수 시스템에 적합한 제어기로써 두 개의 최적 LQR 제어기 구조를 갖는 제어시스템을 제안하였다. 또한 제안한 제어시스템의 성능을 입증하기 위하여 밸런싱 로봇의 자세제어에 적용하여 모의실험과 실험을 수행하였고, PID 제어기와의 비교평가를 통하여 그 우수성을 검증하였다.