자율 드리프트 주행을 위한 차량 거동 한계 분석

좌은혁(Eunhyek Joa),이경수(Kyongsu Yi) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.5

극한성능 향상을 위한 4WD, ESC, ECS 통합 샤시 제어

좌은혁(Eunhyek Joa),이경수(Kyongsu Yi),김길수(Kilsoo Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

This paper presents an integrated chassis control of 4WD(Four wheel drive), ESC(Electronic stability control), and ECS(Electronic controlled suspension) for limit handling. The proposed algorithm consists of three layers : 1) Supervisor, which determine target yaw rate and target velocity from steering wheel angle and acceleration pedal, respectively, 2) Upper level controller, which calculate generalized force to track target values in the manner of sliding mode control method, 3) Lower level controller, which optimally allocates generalized force to actuators. In this study, to achieve limit handling of vehicle, the novel cost function is proposed. The main concept of the cost function is kept the tire stable by monitoring tire saturation with slip information. The proposed algorithm is validated via Matlab/Carsim co-simulation. Compared to base and ESC/4WD module, the proposed algorithm shows stable performance at the limit. The results show that with ESC/4WD modules, the performance at the limit is enhanced, but the yaw rate is oscillated. ECS module can reduce yaw rate oscillation by allocating vertical force.

A lateral driver model for vehicle–driver closed-loop simulation at the limits of handling

Joa, Eunhyek,Yi, Kyongsu,Kim, Kilsoo Taylor Francis 2015 Vehicle system dynamics Vol.53 No.9

<P>This paper presents a lateral driver model for vehicle-driver closed-loop simulation at the limits of handling. An appropriate driver model can be used to evaluate the performance of vehicle chassis control systems via computer simulations before vehicle tests which incurs expenses especially at the limits of handling. The driver model consists of two parts. The first part is an upper-level controller employing force-based approach to reduce the number of unknown vehicle parameters. The feedforward part of the upper controller has been designed by using the centre of percussion. The feedback part aims to minimise 'tangential error', defined as the sum of body slip angle and yaw error, to match vehicle direction and road heading angle. The part is designed to regenerate an appropriate skid motion similar to that of a professional driver at the limits. The second part is a lower-level controller which converts the desired front lateral force to steering wheel angle. The lower-level controller also consists of feedforward and feedback parts. A two-degree-of-freedom bicycle model-based feedforward part provides nominal steering wheel angle, and the feedback part aims to eliminate unmodelled error. The performance of the lateral driver model has been investigated via computer simulations. It has been shown that the steering behaviours of the proposed driver model are quite close to those of a professional driver at the limits. Compared with the previously developed lateral driver models, the proposed lateral driver model shows good tracking performance at the limits of handling.</P>

감/가속 성능 향상을 위한 4WD/ESC 통합 샤시 제어 알고리즘 개발

좌은혁(Eunhyek Joa),이경수(Kyongsu Yi),김길수(Kilsoo Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.IT융합 No.-

Estimation of the tire slip angle under various road conditions without tire–road information for vehicle stability control

Joa, Eunhyek,Yi, Kyongsu,Hyun, Youngjin Elsevier 2019 Control Engineering Practice Vol.86 No.-

<P><B>Abstract</B></P> <P>This paper presents a tire slip angle estimator based on an Interacting Multiple Model (IMM) algorithm for vehicle stability control. The proposed algorithm is capable of estimating the tire slip angles under various road conditions without the prior knowledge of tire and road condition by only using on-board vehicle sensors. Instead of employing tire and road information, the proposed algorithm utilizes multiple numbers of model candidates to represent all aspects of vehicle motions under various road conditions. Each model candidate is a combination of lateral vehicle dynamics and transient/steady state tire dynamics. The proposed algorithm evaluates the fidelity of each model candidate to the current vehicle dynamics with probability. Moreover, in the proposed algorithm, multiple numbers of Kalman filters are embedded with these model candidates as process models. The final estimate of the proposed algorithm in each time step is a linear sum of the <I>posteriori</I> states from multiple embedded filters with the calculated probability as coefficients. The proposed estimation algorithm has been evaluated via vehicle tests. The tests have been conducted on dry asphalt and wet asphalt using a luxury passenger car equipped with a high-performance GPS for reference and data logging computer. The results have shown that the proposed estimator can successfully estimate tire slip angles with satisfactory accuracy under various road conditions</P>

A tyre slip-based integrated chassis control of front/rear traction distribution and four-wheel independent brake from moderate driving to limit handling

Joa, Eunhyek,Park, Kwanwoo,Koh, Youngil,Yi, Kyongsu,Kim, Kilsoo Informa UK (TaylorFrancis) 2018 Vehicle system dynamics Vol.56 No.4

<P>This paper presents a tyre slip-based integrated chassis control of front/rear traction distribution and four-wheel braking for enhanced performance from moderate driving to limit handling. The proposed algorithm adopted hierarchical structure: supervisor - desired motion tracking controller - optimisation-based control allocation. In the supervisor, by considering transient cornering characteristics, desired vehicle motion is calculated. In the desired motion tracking controller, in order to track desired vehicle motion, virtual control input is determined in the manner of sliding mode control. In the control allocation, virtual control input is allocated to minimise cost function. The cost function consists of two major parts. First part is a slip-based tyre friction utilisation quantification, which does not need a tyre force estimation. Second part is an allocation guideline, which guides optimally allocated inputs to predefined solution. The proposed algorithm has been investigated via simulation from moderate driving to limit handling scenario. Compared to Base and direct yaw moment control system, the proposed algorithm can effectively reduce tyre dissipation energy in the moderate driving situation. Moreover, the proposed algorithm enhances limit handling performance compared to Base and direct yaw moment control system. In addition to comparison with Base and direct yaw moment control, comparison the proposed algorithm with the control algorithm based on the known tyre force information has been conducted. The results show that the performance of the proposed algorithm is similar with that of the control algorithm with the known tyre force information.</P>

YAW STABILITY CONTROL OF 4WD VEHICLES BASED ON MODEL PREDICTIVE TORQUE VECTORING WITH PHYSICAL CONSTRAINTS

Kwangseok Oh,Eunhyek Joa,Jisoo Lee,Jaemin Yun,Kyongsu Yi 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5

This paper describes a yaw stability control algorithm of 4WD vehicles based on model predictive torque vectoring with physical constraints. A vehicle planar model based predictive rear and all-wheel torque vectoring algorithms were developed for 4WD vehicles by considering predictive states and driver’s steering wheel angle. The physical constraints applied to the model predictive control consist of three types: limitation on magnitude of tire force, change rate of tire force, and output torque of transfer case. Two types of torque vectoring algorithms, rear-wheel and all-wheel, were constructed for comparative analysis. The steady state yaw rate was derived and applied as a desired value for yaw stability of the vehicle. The algorithm was constructed in a MATLAB/Simulink environment and the performance evaluation was conducted under various test scenarios, such as step steering and double lane change, using the CarSim software. The evaluation results of the predictive torque vectoring showed sound performance based on the prediction of states and driver’s steering angle.

기동성을 위한 후륜 조향 장치의 성능 평가

안국진(Kookjin Ann),좌은혁(Eunhyek Joa),박관우(Kwanwoo Park),서지윤,윤영식(Youngsik Yoon),김영일,이경수(Kyongsu Yi) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.5

A Vehicle Motion Predictor for Autonomous Racing

Sanghoon Oh(오상훈),Eunhyek Joa(좌은혁),Kyongsu Yi(이경수) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

This paper presents a vehicle motion predictor for an autonomous racing system to assure safety when driving in limit handling situation. The proposed algorithm consists of two sequential parts; (1) Tire model identifier (2) Prediction of vehicle state. In the tire model identifier, parameters of a nonlinear tire model are identified through nonlinear optimization. In the prediction of vehicle sate, future vehicle states are calculated through numerical integration of a 2- DOF bicycle model that includes previously identified tire model. Moreover, assuming normal distribution of prediction error of each state, the probability of lateral instability and track escape of the future can be calculated. The proposed algorithm has been validated through computer simulations. The results show that the algorithm well predicts future vehicle states.

Integrated chassis control for optimized tyre force coordination to enhance the limit handling performance

Her, Hyundong,Joa, Eunhyek,Yi, Kyongsu,Kim, Kilsoo Professional Engineering Publishing Ltd 2016 Proceedings of the Institution of Mechanical Engin Vol. No.

<P>This paper proposes a coordinated control algorithm of the differential braking, the front and rear traction torques and the active roll moment to enhance the limit-handling performance. The coordinated algorithm is designed to maximize the driving velocity while keeping the vehicle in a lane. First, the analysis of the cornering dynamics is described to consider the non-linear characteristics of the tyres during acceleration or deceleration. The target vehicle motions are determined on the basis of the driver's intention and the current states of the vehicle. An optimization-based control allocation strategy is utilized to distribute the actuator control inputs optimally by considering the tyre and vehicle limitations. Closed-loop simulations of a driver-vehicle-controller system were conducted to investigate the performance of the proposed control algorithm. The performance of the coordinated algorithm was compared with those of the individual coordination algorithms. The simulation results show that the proposed integrated chassis controller improves the performance in high-speed cornering with respect to the driving speed without losing stability compared with simple coordination chassis control systems.</P>