Force-back Control Method of Active Steering using a Planetary Gear System

Transcription

1 , () Force-back Control Method of Active Steering using a Planetary Gear System Ken-ichiro Aoki and Yoichi Hori (The University of Tokyo) Abstract Every year, thousands of people are killed by traffic accident in Japan. Active steering system, which helps drivers avoiding in accidents, has become one of the most important technologies of automobiles to reduce the number of traffic accidents. But active steering has not yet been installed into present automobiles because there is a difficult problem to be solved. The problem is that the active control disturbs the information of the vehicle attitude for the driver and might confuse the driver. In this paper, we introduce a novel experimental steering system, which has one planetary gear and two electric motors, to realize active steering and solve the problem. Experimental results prove that proposed steering actuator realizes active steering control. Finally we propose the control method to prevent interference between active control and information for the driver. : ( Keywords: electric power steering, active steering, planetary gear, sensorless ) 2.. ABS(Anti-lock Brake System) (AFS) AFS AFS (SBW) (EPS) AFS () 2 AFS AFS AFS 2 EPS 3 AFS 2. (AFS) 2 AFS AFS AFS AFS (SBW) SBW AFS AFS (2) (3) SBW SBW (4) AFS

2 (EPS) (5) EPS 5% (6) (7) EPS Electric s Differential System Electric s (a) (b) Torque Sensor 3 Fig. 3. Two types of active steering system. Electric 2 3. EPS Rack & Pinion EPS Fig.. Configuration of EPS system. EPS EPS 2 2 EPS 2 : 2 (8) 4 4 A B C D Kw Th Tr Js s2 θs Torque Sensor Kt Cw Jf s s θf Sun Gear (A) 2 EPS 3 (a) (SBW) (b) 2 (4) Fig Planetary Gear (B) Internal Gear (C) Carrier (D) Planetary gear system. A, C, D θ A, T A, θ C, T C, θ D, T D () (2) θ C = + θa + θd () 2

3 T A = TC = TD (2) + = Z C/Z A 5 EPS ( ) EPS ( ) & θw θs θf Sub Main θm :5 MOSFET V 25A PWM H8/352F(25MHz) PI PD 2 2 ( ) 2 2 θ s, θ f, θ r N r θ f =(+)θ s + θr N r (4) Rack & Pinion 5 Fig. 5. Proposed steering system. () (θ C=θ D) EPS AFS θr Fig Picture of experimental system. θ r = (θ s θ )/Nr (3) θ s, θ f N r EPS 2mm 4mm EPS 45A :8 EPS 2 5. (2) 5 (2) EPS (3) i assist =(+ + Nw Ka) i sub (5) N r 3

4 << Planetary Gear System Table. Parameters. (a) (b) (K f )[Nm/rad] (C f )[Nm/sec/rad].4 Rotary Encoder 7 Fig. 7. Picture of experimental system. Sub- Steering Torque [Nm] Steering Wheel Enc θs θg Enc Planetary Gear Sub RS232C EPS Steering Torque [Nm] Steering Angle [deg] (a) Fig Configuration of experimental system Steering Angle [deg] (b) N w K a (9) K a =4 EPS (a) (b) 9 Fig. 9. Chart of steering torque and angle. 3. AFS 3. AFS AFS θ 2 θ -6.3 K f =.47[Nm/rad], C f =( ) 9 3 AFS 4

5 θ s θ f θ g Angle [deg] Torque [Nm] 4 2 Ring Gear Front Wheel.6.5 Steering Torque Time [sec] Fig.. control. Experimental result on active steering AFS 3 AFS AFS θ () AFS 9 AFS 3 4 AFS AFS AFS AFS Angle [deg] Torque [Nm] Ring Gear Front Wheel Steering Torque Time [sec] Fig.. control. Experimental result on active steering AFS AFS ( ()) SAT() AFS AFS AFS AFS AFS 4. AFS 4. AFS AFS AFS 5

6 SAT SAT K a = θf θ s K a (6) AFS 9 3 AFS Angle [deg] Torque [Nm] Ring Gear Front Wheel Steering Torque Time [sec] 2 Fig. 2. Experimental result of proposed method with force control. AFS AFS 5. AFS AFS AFS AFS AFS AFS ( ) Kenichiro Aoki, Yoichi Hori, Realization of Active Steering System using Planetary Gear, Japan Industry Application Society Conference, 24. (in Japanese),,,, 24 2 Shiro Nakano, Takanobu Takamatsu, Osamu Nishihara, Hiromitsu Kumamoto, Steering Control Strategies for the Steer-by-Wire System, Transaction of JSAE, Vol.3, No.2, pp.53-58, 2. 3 Shirou Nakano, Katsutoshi Nishizaki, Osamu Nishihara, Hirimitsu Kumamoto, Steering Control Strategies for the Steer-by-Wire System (Second Report), Transaction of JSAE, Vol.33, No.3, pp.2-26, Philip Koehn and Michael Eckrich, Active Steering - The BMW Approach Towards Modern Steering Technology, SAE paper, 24--5, Nakayama, T. and Suda, E., The present and future of electric power steering, Int. J. of Vehicle Design, Vol. 5, Nos 3/4/5, pp NSK Technical Journal, No.672, 2. 7 Web site of Toyota Corp., cars/ crown majesta/index.html 8 Sumio Motoyama, The Possibilities of Steer-by-Wire on Vehicle Dynamics, Journal of SAE of Japan, Vol.57, No.2, pp.39-43, 23. 9, (), pp.244, 24. 6