Journal of Mechanical Science and Technology 23 (2009) 1046~1049 www.springerlink.com/content/1738-494x DOI 10.1007/s12206-009-0338-z Journal of Mechanical Science and Technology Development of enhanced ESP system through vehicle parameter estimation † Hansung Lee 1 , Kihong Park 2,* , Taehun Hwang 3 , Keunje Noh 1 , Seung-Jin Heo 2 Jay Il Jeong 2 , Seongho Choi 4 , Byunghak Kwak 4 and Sewoong Kim 4 1 Graduate School of Automotive Engineering, Kookmin University, Seoul, 136-702, Korea 2 School of Mechanical and Automotive Engineering, Kookmin University, Seoul, 136-702, Korea 3 Automotive Components Tech Center, Songdo Technopark, Incheon, 406-840, Korea 4 ABS R&D Center, Mando, Gyeonggi-do, 451-820, Korea (Manuscript Received December 24, 2008; Revised March 16, 2009; Accepted March 16, 2009) -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Abstract In this research, an enhanced lateral stability control system has been developed for a vehicle. The system consists of a vehicle parameter estimation part and an enhanced ESP control logic part. The vehicle parameter estimation was conducted by considering the physical relationship among the longitudinal dynamic components. The enhanced ESP logic was designed so that the controller gains change adaptively to the vehicle parameter variation. All the system components were tested in a simulation environment, while the vehicle mass estimation algorithm was also tested in the field. The results indicated that the lateral vehicle stability limit can be improved with the designed ESP system. Keywords: ESP (Electronic Stability Program); Load adaptive control; Optimization; Parameter estimation --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 1. Introduction ESP (Electronic Stability Program) is an electronic chassis control system whose objective is to maintain lateral vehicle stability during critical cornering [1]. At the beginning of its control logic, the ESP algo- rithm computes the reference yaw rate as the target to follow, using a lateral vehicle model. The parameters of the vehicle model, however, can change signifi- cantly due to many passengers or heavy loads. The amount of vehicle mass variation, for example, can be bigger than the vehicle’s curb weight for some vehi- cles. Hence, it is very important for the ESP logic to account for any significant change in the vehicle pa- rameters, since otherwise, the ESP logic can worsen vehicle lateral stability by setting an improper target in dangerous cornering maneuvers. Many previous studies in the area of the vehicle pa- rameter estimation have adopted the recursive least square method [2, 3]. This online version of the un- constrained least square method is reliable in deter- mining the parameters of a mathematical function that matches the vehicle performance in its transient mo- tion. However, due to the possibility of non-unique minimum solutions, the algorithm may have difficulty in the process of extracting the physical parameters from the mathematical solution. The recent work of Bosch states that through vehicle mass estimation, ESP could improve the braking efficiency and per- formance of stability control [4]. In this research, an enhanced ESP system has been developed for a passenger vehicle. The system con- sists of two parts: a vehicle parameter estimation part and an enhanced ESP control logic. The vehicle pa- rameter estimation was conducted by considering the physical relationship among the longitudinal dynamic †This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20-23, 2008. * Corresponding author. Tel.: +82 2 910 4689, Fax.: +82 2 910 4839 E-mail address: kpark@kookmin.ac.kr © KSME & Springer 2009