International Journal of Computer Theory and Engineering, Vol. 8, No. 3, June 06 Advanced Smart Cruie Control with Safety Ditance Conidered Road Friction Coefficient Doui Hong, Chanho Park, Yongho Yoo, and Sungho Hwang Abtract Thi reearch ugget the velocity controller with advanced mart cruie control (ASCC) with top & go control conidering the urface friction coefficient and applying a afety ditance. A afety ditance affect quality of cruie control. If a afety ditance i too hort, the probability to caue a colliion get greater wherea if it i too long, it can caue traffic congetion. Thu, calculating the optimal afety ditance i very important. In thi tudy, we ued fitting function to obtain a baic afety ditance and then added the μ-afety ditance, conidering friction coefficient and relative velocity, to calculate final afety ditance. We invented ASCC and top & go control by conidering velocity of vehicle to maintain the afety ditance and relative velocity at the ame time. Carim wa ued for imulation and we found that while a vehicle with the velocity controller, calculating the velocity and location difference between preceding and following vehicle with four friction coefficient, it keep a afety ditance. Index Term Advanced mart cruie control (ASCC), friction coefficient, afety ditance. I. INTRODUCTION Adaptive Cruie control with top & go ha been highlighted in the field of longitudinal velocity control of vehicle. Thi ytem allow vehicle to keep a certain ditance and to follow a preceding vehicle by calculating the peed of front preceding vehicle, peed of following vehicle, and the ditance between car. One of important component in Adaptive Cruie control with top & go ytem i calculating a afety ditance. Many reearcher calculated it by multiplying the peed of vehicle and time-contant []. Some reearcher uggeted to add anti-colliion contant to the equation []-[4]. Deng and Yingping defined the econd degree equation of the afety ditance according to the peed uing fitting function [5]. The afety ditance hould be the ditance preventing colliion with preceding vehicle. Breaking ditance depend on urface friction coefficient, o that the afety ditance hould alo vary from the urface friction coefficient [6]. In thi paper, we derive a baic afety ditance formula by Manucript received November 30, 04; revied March, 05. Thi reearch wa upported by Baic Science Reearch Program through the National Reearch Foundation of Korea (NRF) and funded by the Minitry of Education (NRF-03RAA005594). Doui Hong, Chanho Park, and Sungho Hwang are with School of Mechanical Engineering, Sungkyunkwan Univerity, Suwon, 440-746, Republic of Korea (e-mail: hdo436@gmail.com, pch885@gmail.com, hh@me.kku.ac.kr). Yongho Yoo i with the Korea Automotive Technology Intitute, 303 Punge-ro, Punge-myeon, Dongnam-gu, Cheonan-i, Chungnam 330-9, Republic of Korea (e-mail: yhyoo@katech.re.kr). uing fitting function and braking ditance data, provided by Road Traffic Authority. Moreover, we obtained μ-afety ditance uing a friction coefficient of urface and a calculate afety ditance of vehicle. After that, we calculate deired velocity of vehicle utaining afety ditance. According to calculation, after we deigned ASCC with top & go control, we demontrated the utility of μ-afety ditance through the graph of vehicle interval and peed and confirmed the performance of ASCC with top & go control. II. CACUATION OF SAFETY DISTANCE In thi tudy, we obtained a baic afety ditance uing fitting function and add μ-afety ditance, conidering a friction coefficient and a relative velocity, to the reult to calculate a final afety ditance. A. Calculation of Baic Safety Ditance In thi reearch, a baic afety ditance mean a braking ditance of vehicle in uual road condition. Provided braking ditance data by Road Traffic Authority of Korea wa ued becaue braking power varied from type of vehicle when general vehicle brake uddenly. A baic afety ditance can be obtained by applying fitting function to previou data. Through thi progre, baic afety ditance can be expreed a follow. a a v a v b 3 () In the above equation, where v i the peed of vehicle, a mean the minimum maintained ditance when two vehicle top and a, a, and a 3 are all contant. B. Calculation of μ-safety Ditance In practical environment, friction coefficient between road and tire vary from environment. In general, a friction coefficient of dry road i 0.8, that of wet road i 0.5, that of nowy road i 0.3, and that of icy road i 0. [7]. A friction coefficient make a braking ditance to differ. Thu, a friction coefficient i abolutely neceary when a afety ditance i calculated. In thi tudy, after obtaining a friction coefficient uing parameter, which can be obtained only in vehicle, we calculated μ-afety ditance by uing the reult. To derive a imple equation, we only conidered drag reitance and ignored rolling reitance and gradient reitance to calculate. Here, driving force i calculated by multiplying normal force and friction coefficient, auming that a front wheel drive car accelerate. b DOI: 0.7763/IJCTE.06.V8.043 98
International Journal of Computer Theory and Engineering, Vol. 8, No. 3, June 06 F ma driving force drag force h lr ( mg mg ) Cw A v l l If we derive the equation for μ from thi equation, it can be expreed a equation (3). () h lr mg mg Cw A v ma 0 l l (3) Therefore, the afety ditance follow. m b m v v0 (7) g v v ( a a v a v ) g 3 i finally expreed a (8) Thu, a final equation i derived a follow. lr lr h mg ( mg ) 4 mg ( Cw A v ma) l l l (4) h mg l where l i a ditance between the center of a front wheel and the center of a rear wheel, l f i a ditance between the center of vehicle and the center of a front wheel, l r i a ditance between the center of vehicle and the center of a rear wheel, and h i a height from the ground to the center of vehicle height. Alo, where mean air denity, C mean drag coefficient, A mean the front part area of vehicle, m i vehicle weight, a i the acceleration of vehicle, and g i acceleration of gravity. Following graph i μ-lip curve by calculating equation (4). Fig.. μ-lip curve. According to thi, we aumed a friction coefficient and a calculated μ-afety ditance. When a moving object with a certain peed v 0 decelerate with a certain acceleration a, the ditance that the object move and the peed v are a follow. 0 v 0t / at (5) v v0t at (6) Here, acceleration a i g, o that μ-afety ditance m i expreed a a following equation. w III. VEOCITY CONTRO If a afety ditance between a preceding vehicle and a following vehicle i given in Adaptive Cruie Control, a eential control component i a required velocity which can maintain a given afety ditance. We ued variou component uch a preceding vehicle velocity v, following vehicle velocity v and a ditance from preceding vehicle to obtain proper velocity. The peed plan can be obtained by conidering the ratio of a ditance from preceding vehicle and a afety ditance. Briefly, we calculate the peed plan by calculating the um of both a velocity component of maintaining certain ditance with preceding vehicle v following and a velocity component v relative which conider and relative velocity. When velocity v decreae linearly depending on a ditance with preceding vehicle, a moving ditance by time can be defined a equation (). d v k dt d kdt e, v ke, a k e kt 0 kt 0 kt 0 k mean a negative contant. It wa found that by mean of thi equation, the velocity and acceleration decreae a vehicle attain a afety ditance. In cae when 0, it mean that a following vehicle can approach the preceding car acro a afety ditance. Thu, to prevent a colliion, a velocity of the following car i required to decreae rapidly by driving a quaring ditance that i between a preceding car and the following car. Squaring a decelerating velocity i different from the conventional calculation. Therefore, the moving ditance by time can be obtained a follow. v k d kdt ( 0 kt ) 4 (9) (0) Unlike the above equation, it i found that variation of moving ditance get greater and the ditance between vehicle get far rapidly a time goe. 99
International Journal of Computer Theory and Engineering, Vol. 8, No. 3, June 06 To derive equation of velocity, if the ditance with preceding car get cloer to, the velocity of vehicle change linearly with the velocity of preceding vehicle and when it become that, the deired velocity of vehicle v d hould equal to v. Moreover, conidering a relative velocity, a afety ditance, and a ditance between a preceding vehicle and a following vehicle, the vehicle hould maintain the given afety ditance at the ame peed of preceding vehicle by additional acceleration and deceleration. Further, when, it hould decelerate rapidly and prevent a colliion with preceding car. We ugget the equation of peed control which atifie thee condition a follow. (c) vd ( v v ) v, ( v v ) ( ) v, 0 0 () IV. SIMUATION AND RESUTS TABE I: PARAMETERS OF SIMUATION Drag coefficient 0.35 Air denity.06kg/m 3 Vehicle cro ection areav.6m Center of Gravity height 540mm Wheel bae 978mm ongitudinal poition of front wheel from vehicle CG 06mm ongitudinal poition of rear wheel from vehicle CG Wheel diameter Vehicle ma (a) (b) 56mm 60mm 74kg (d) Fig.. Time-velocity graph. (a) μ=0.8. (b) μ=0.5. (c) μ=0.3.(d) μ=0.. msd (with μ-afety ditance), nmsd (without μ-afety ditance). To verify equation for a afety ditance and a velocity controller we uggeted, we performed imulation uing Carim and pecified parameter a follow. A initial condition, initial velocitie of preceding vehicle and following vehicle are 0km/h, and a ditance between vehicle i 0m. Auming the ituation that the preceding car accelerated up to 70km/h, it braked uddenly, and it accelerated up to 50km/h and again it braked uddenly. In thi cae, we preumed that the delay time when the following vehicle received the location of preceding vehicle, calculated and controlled it peed i 0.3. We carried out the imulation by auming variou road condition (e.g. dry (μ=0.8), wet (μ=0.5), nowy (μ=0.3), icy (μ=0.)) and oberved motion of following vehicle. A vehicle, which μ-afety ditance wa applied, i called a msd and the other vhicle without μ -afety ditance ytem i called a nmsd. The minimum afety ditance a wa et a.5m. The velocity algorithm of each following car wa performed equally. Fig. how the peed of preceding vehicle, the peed of following vehicle with the μ-afety ditance ytem, and the peed of following vehicle without the μ-afety ditance ytem. In cae of the vehicle, which μ-afety ditance i applied, it wa oberved that it moothly approached to the preceding car and manipulated it peed to be equal to the preceding car, compared to the other vehicle. In cae of the vehicle without the μ-afety ditance ytem, when it approache the topped car, it urgently low down and top. On the other hand, when the car with μ-afety ditance ytem 00
International Journal of Computer Theory and Engineering, Vol. 8, No. 3, June 06 approached the preceding car, it approached moothly with low velocity. In Fig. (c) and (d), peed data of the vehicle without μ-afety ditance ytem after colliion in t plotted in the graph becaue it collided with the preceding car. A hown in Fig. 3, the change of ditance between a preceding vehicle and a following vehicle under the variou circumtance are plotted in the graph. In cae of Fig. 3(c) and (d), it how that the vehicle without the μ-afety ditance ytem ha a minu ditance between preceding and following car, o that it preent that the following one crahed with the preceding one. Further, if μ-afety ditance ytem i applied, the afety ditance between preceding and following vehicle varie from each friction coefficient wherea if it i not applied, the afety ditance come out ame even under variou friction coefficient. (d) Fig. 3. Time-ditance graph (a) μ=0.8. (b) μ=0.5. (c) μ=0.3. (d) μ=0.. msd (with μ-afety ditance), nmsd (without μ-afety ditance). (a) V. CONCUSION In thi paper, we calculated the afety ditance by conidering the friction coefficient and derived the equation of a required velocity, thu it allow vehicle to go a it maintain the afety ditance. Alo, we demontrated that the given afety ditance i neceary through imulation and oberved the vehicle with peed plan run a it keep the afety ditance. Epecially, it i found that if a vehicle with μ-afety ditance ytem run, it can avoid colliion, maintain the afety ditance and follow the preceding vehicle even under unfavorable road condition with low friction coefficient. The mooth driving reduce driver anxiety and further it help driver to drive vehicle tably under rainy and nowy condition. In hort, thi technique i expected to raie convenience of driver in every condition. (b) (c) REFERENCES [] Z. Ali, A. A. Popov, and G. Charle, Model predictive control with contraint for a nonlinear adaptive cruie control vehicle model in tranition manoeuvre, Vehicle Sytem Dynamic, vol. 5, no. 6, pp. 943-963, 03. [] S. Oncu et al., Cooperative adaptive cruie control: Network-aware analyi of tring tability, Browe Journal & Magazine, vol. 5, iue 4. [3] C. C. Tai, S. M. Hieh, and C. T. Chen, Fuzzy longitudinal controller deign and experimentation for adaptive cruie control and top&go, Journal of Intelligent & Robotic Sytem, vol. 59, no., pp. 67-89, 00. [4] P. Shakouri, A. Ordy, and M. R. Akari, Adaptive cruie control with top&go function uing the tate-dependent nonlinear model predictive control approach, ISA Tranaction, vol. 5, no. 5, pp. 6-63, 0. [5] P. Deng and Y. P. Zheng, Velocity difference control baed on dynamic tracking of afe following ditance in the proce of vehicle following, Intelligent Tranport Sytem, vol. 8, no. 3, pp. 3-43, 04. [6] S. W. Moon, I. Moon, and K. S. Yi, Deign, tuning, and evaluation of a full-range adaptive cruie control ytem with colliion avoidance, Control Engineering Practice, vol. 7, no. 4, pp. 44-455, 009. [7] C.-Y. ee, K. Hedrick, and K.-S. Yi, Real-time lip-baed etimation of maximum tire-road friction coefficient, IEEE/Ame Tranaction on Mechatronic, vol. 9, no., pp. 454-458, 004. Doui Hong received the B.S. degree in mechanical engineering from Sungkyunkwan Univerity, Suwon, Korea in 04. He i currently working toward the M.S. degree with the School of Mechanical Engineering, Sungkyunkwan Univerity, Suwon, Korea. Hi reearch interet include the driverle vehicle and vehicle dynamic. 0
International Journal of Computer Theory and Engineering, Vol. 8, No. 3, June 06 Chanho Park received the B.S. degree in mechanical engineering from Sungkyunkwan Univerity, Suwon, Korea, in 04. He i currently working toward the M.S. degree with the School of Mechanical Engineering, Sungkyunkwan Univerity, Suwon, Korea. Hi reearch interet include the driverle vehicle and vehicle dynamic. Sungho Hwang received the B.S. degree in mechanical deign and production engineering and the M.S. and Ph.D. degree in mechanical engineering from Seoul National Univerity, Seoul, Korea, in 988, 990, and 997, repectively. He i currently an aociate profeor with the School of Mechanical Engineering, Sungkyunkwan Univerity, Suwon, Korea. Yongho Yoo received the B.S. degree in automotive engineering from Kongju National Univerity, Cheonan, Republic of Korea in 0 and he i currently working for a M.S. degree in mechatronic engineering at Sungkyunkwan Univerity, Suwon, Republic of Korea. Hi reearch interet are vehicle dynamic, vehicle tability control and tyre wet grip for tyre labeling ytem. 0