주행로봇 제어를 위한 험지의 최대마찰계수 추정

강현석(Hyun-Suk Kang),곽윤근(Yoon Keun Kwak),최현도(Hyun-Do Choi),정해관(Hae-Kwan Jeong),김수현(Soo-Hyun Kim) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.10

When mobile robots perform the mission in the rough terrain, the traversability depended on the terrain characteristic is useful information. In the travers abilities, wheel-terrain maximum friction coefficient can indicate the index to control wheel-terrain traction force or whether mobile robots to go or not. This paper proposes estimating wheel-terrain maximum friction coefficient. The existing method to estimate the maximum friction coefficient is limited in flat terrain or relatively easy driving knowing wheel absolute velocity. But this algorithm is applicable in rough terrain where a lot of slip occurred not knowing wheel absolute velocity. This algorithm applies the tire-friction model to each wheel to express the behavior of wheel friction and classifies slip-friction characteristic into 3 major cases. In each case, the specific algorithm to estimate the maximum friction coefficient is applied. To test the proposed algorithm’s feasibility, test bed(ROBHAZ-6WHEEL) simulations are performed, And then the experiment to estimate the maximum friction coefficient of the test bed is performed. To compare the estimated value with the real, we measure the real maximum friction coefficient. As a result of the experiment, the proposed algorithm has high accuracy in estimating the maximum friction coefficient.

Integrated Estimation of Vehicle States, Tire Forces, and Tire-Road Friction Coefficients

Tesheng Hsiao,Jing-Yuan Lan,Hanping Yang 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Information about the vehicle states (e.g. the sideslip angle and the longitudinal velocity), tire forces, and tire-road friction coefficients is crucial for advanced vehicular active safety systems. In particular, the latest high-performance control system based on optimally distributing and controlling all tire forces requires feedback of the tire forces and the tire-road friction coefficient of each individual tire. Therefore, estimating all or parts of the vehicle/tire/road states from available sensor measurements in production vehicles has long been an active research topic in both academia and industry. Despite recent advances in automotive estimation technologies, it remains an open question on identifying the tire-road friction coefficient of each individual tire. This paper proposes an integrated estimation system that provides accurate estimates of the vehicle/tire/road states from available sensor measurements. More importantly, the tire-road friction coefficient of each tire can be separately estimated. The performance of the proposed estimation system is verified by simulations based on a complex nonlinear vehicle/ tire model.

순환 최소자승법을 이용한 전동기 관성과 마찰계수 추정

金智慧(Ji-Hye Kim),崔鐘宇(Jong-Woo Choi) 대한전기학회 2007 전기학회논문지 Vol.56 No.2

This paper proposes the algorithm which estimates moment of the inertia and friction coefficient of friction for high performance speed control of electric motor. The proposed algorithm finds the moment of inertia and friction coefficient of friction by observing the speed error signal generated by the speed observer and using Recursive Least-Mean-Square method(RLS). By feedbacking the estimated inertia and estimated coefficient of friction to speed controller and full order speed observer, then the errors of the inertia and coefficient of friction and speed due to the inaccurate initial value are decreased. Inertia and coefficient of friction converge to the actual value within several times of speed changing. Simulation and actual experiment results are given to demonstrate the effectiveness of the proposed parameter estimator.

다짐밀도 예측을 위한 구형입자를 활용한 DEM의 적용성 평가

윤태영 한국도로학회 2018 한국도로학회논문집 Vol.20 No.6

PURPOSES: In this paper, the packing degrees of binary granular mixtures under vibration compaction were simulated by using DEM with spherical particles to evaluate the applicability of the DEM for aggregate packing degree estimation. METHODS: The packing degrees of fine particles, coarse particles, and their mixture with different fine particle fractions were evaluated in DEM simulation for given various material property conditions. In order to check the validity of estimated packing degrees of particle mixtures, analytical model such as Furnas model that is capable of considering wall effect and loosening effect. RESULTS : DEM with spherical particles showed good agrement with analytical solution in terms of the packing degrees of binary granular mixtures with various fine particle fractions for most of conditions. Also, it was found that not the vibration amplitude but the ratio of particle diameter with vibration amplitude should be considered to explain the susceptibility of particle packing degree with vibration amplitude for the same acceleration condition and that the reduction in elastic modulus to shorten computational simulation time should be carefully considered when the packing degree is the most important concern. CONCLUSIONS: It was concluded that DEM with spherical particles are good enough to estimate the packing degree of binary granular particles for most of conditions. However, the effect of inter-particle frictions between fine and coarse particles have to be studied further in order to clarify the issue relating poor predictions for high inter-particle friction conditions.

토크컨버터 바이패스 클러치의 마찰계수 적응 슬립제어

한진오(Jin-Oh Hahn),이교일(Kyo Il Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

This paper presents an adaptive approach to control the amount of slip of the torque converter bypass clutch using its estimated friction coefficient. The proposed approach can be readily implemented using the inexpensive speed sensors currently installed in an automobile. A measurement feedback control law to drive the slip error to zero together with an adaptation law to identify the unknown friction coefficient is developed using the Lyapunov control design method. The robustness of the control and adaptation laws to parametric and/or torque uncertainties as well as the convergence of the friction coefficient are investigated. Simulation results verify the viability of the proposed control algorithm in real-world vehicle control applications.

Analytic Approaches for Keeping High Braking Efficiency and Clamping Efficiency of Electro Wedge Brakes

Shin, Dong-Hwan,Lee, Seonghun,Jeong, Choong-Pyo,Kwon, Oh-Seok,Park, Tae-Sang,Jin, Sung-Ho,Ban, Dong Hoon,Yang, Seung-Han Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.7

The transfer from engine drive vehicles to electric vehicle has been proceeding due to fuel exhaustion, higher fuel costs, and environmental restrictions. This trend has also led to a transition in brake system from the hydraulic brake system to the electric brake system, which uses electric power. This electric brake system has led to an enhancement of safety and eco-friendliness due to a reduction braking distance, a rapid-response property, and the elimination of braking oil. However, one of the big problems to solve for practical usages is the need of a high power motor to enable braking forces as strong as those of hydraulic brake systems. Therefore, it is necessary to develop high efficiency electro mechanical brakes with a proper reinforcement mechanism to solve this problem. In this paper, we describe a wedge structure that has a self-reinforcing effect; we propose a proper actuating direction for a movable wedge to obtain greater clamping efficiency and braking efficiency, which will mean a better relation of the motor force as the input to the braking force as the output. Further, we propose the method to keep the most braking efficiency and clamping efficiency without reference to the variations of frictional coefficient.

Analytic Approaches for Keeping High Braking Efficiency and Clamping Efficiency of Electro Wedge Brakes

신동환,이성훈,Choong-Pyo Jeong,권오석,박태상,진성호,반동훈,양승한 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

The transfer from engine drive vehicles to electric vehicle has been proceeding due to fuel exhaustion, higher fuel costs, and environmental restrictions. This trend has also led to a transition in brake system from the hydraulic brake system to the electric brake system, which uses electric power. This electric brake system has led to an enhancement of safety and eco-friendliness due to a reduction braking distance, a rapid-response property, and the elimination of braking oil. However, one of the big problems to solve for practical usages is the need of a high power motor to enable braking forces as strong as those of hydraulic brake systems. Therefore, it is necessary to develop high efficiency electro mechanical brakes with a proper reinforcement mechanism to solve this problem. In this paper, we describe a wedge structure that has a self-reinforcing effect; we propose a proper actuating direction for a movable wedge to obtain greater clamping efficiency and braking efficiency, which will mean a better relation of the motor force as the input to the braking force as the output. Further, we propose the method to keep the most braking efficiency and clamping efficiency without reference to the variations of frictional coefficient.

Detection of Critical Driving Situations Based on Wheel-Ground Contact Normal Forces

Arjon Turnip,Le Hoa Nguyen,Keum-Shik Hong 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

To develop an effective vehicle control system, it is needed to estimate vehicle motions accurately, and theestimation of reliable road frictions is one of the most important steps to achieve this goal. In the absence of commercially available transducers to measure the friction coefficient directly, various types of estimation methodshave been investigated in the past. Most models in the literature usually use low degrees of freedom. Also, these models have different values from the real vehicle motions and have a difficulty to adapt with new technologies. In this paper, a new estimation process is proposed to estimate tire forces and vehicle state histories, that is, longitudinal and lateral velocities, angular velocity and rolling radius of wheels, and side slip, pitch and roll angle based on extended Kalman filter, and road friction coefficient based on a recursive least squares method. These methods use the measurements from currently available standard sensors. For such estimation, a fourteen degree-of-freedom nonlinear vehicle model was developed. The estimated results are compared with the results obtained from CarSim using the same parameter values to verify the proposed model.

양산자동차 부착 센서를 활용한 노면마찰계수 추정 알고리즘 개발

한상윤(Sangyun Han) 한국자동차공학회 2018 한국자동차공학회 학술대회 및 전시회 Vol.2018 No.11

In this study, we proposed a road surface friction coefficient estimation algorithm using a mass production vehicle sensor. The algorithm uses the current friction force as the road surface friction coefficient when the wheel slip occurs, and gradually increases the road surface friction coefficient calculated at the previous period when the wheel slip does not occur. By using the proposed algorithm, the real vehicle validation test was performed on the dry asphalt surface and ice surface. As a result of the test, it took up to 0.9 seconds to judge the coefficient of friction and judgment value of road friction coefficient showed error of maximum 0.2μ.

ESTIMATION OF MAXIMUM ROAD FRICTION COEFFICIENT BASED ON LYAPUNOV METHOD

X. XIA,L. XIONG,K. SUN,Z.-P. YU 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.6

With the real time and accurate information of motor torque and rotation speed of the four-in-wheel-motordrive electric vehicles, a slip based algorithm for estimating maximum road friction coefficient is designed using Lyapunov stability theory. Modified Burckhardt tire model is used to describe longitudinal slip property of the tire. By introducing a new state variable, a nonlinear estimator is proposed to estimate the longitudinal tire force and the maximum road friction coefficient simultaneously. With the appropriate selection of estimation gain, the convergence of the estimation error of the tire longitudinal force and maximum road friction coefficient is proved through Lyapunov stability analysis. In addition, the error is exponentially stable near the origin. Finally the method is validated with Carsim-Simulink co-simulation and real vehicle tests under multi working conditions in acceleration situation which demonstrate high computational efficiency and accuracy of this method.