and Effects of Vehicle Body Motion on Handling Quality Improvement - PowerPoint PPT Presentation

Driver Model Based Handling Quality Evaluation and Effects of Vehicle Body Motion on Handling Quality Improvement with G-Vectoring Control (GVC) Masato Abe Kanagawa Institute of Technology Japan

Introduction and Outline of The Lecture 1. G-Vectoring Control (GVC) is a vehicle motion control in which the longitudinal motion is controlled depending on the lateral motion . 2 . Mazda has introduced passenger cars with GVC into real market and significant effects of GVC on improving vehicle handling performance not necessarily during severe motion but in a normal vehicle motion by ordinary drivers have been confirmed. 3. A specific feature of the effects of GVC is that though the control gain of the longitudinal motion is very small, a big performance improvement in lateral motion of the driver-vehicle system is available. Therefore, fundamental effects of GVC on handling performance especially on a subtle influence on driver’s handling quality evaluation should be investigated satisfactorily. 4. Since the subjective handling quality evaluation by the ordinary drivers is not always consistent and reliable, a driver model based evaluation method , which is more objective and quantitative evaluation method, has been introduced. 5. The fundamental effect of GVC itself on the handling quality is experimentally investigated using the experimental full drive-by-wire electric powered vehicle by the model based evaluation method. 6. As GVC controls the longitudinal acceleration depending on lateral acceleration, it directly affects the body motion and it seems that a vehicle body motion has a significant effect on the vehicle handling quality evaluation with GVC. Therefore, in order to investigate the effects of GVC on handling quality more in detail, the experimental analysis how the vehicle body motion especially the pitch motion affects the effects of GVC on the handling quality evaluation is investigated.

Overview of G-Vectoring Control (GVC)

Control algorithm of GVC 𝑫 𝒚𝒛 𝑯 𝒚𝒅 = −𝒕𝒉𝒐 𝑯 𝒛 ∙ 𝑯 𝒛 𝑯 𝒛 𝟐 + 𝑼𝒕 Longitudinal motion is controlled in coordination with the lateral motion 4 𝑯 𝒚𝒅 ： Longitudinal acceleration command, 𝑫 𝒚𝒛 ： Control gain, 𝑯 𝒛 ： Lateral acceleration

Movement of ball-in-bowl on board with GVC draws G-G diagram during entering into and out of the curve The name “G - Vectoring Control” comes from this change of the direction of resultant acceleration

Source ： www.mazda.co.jp/dynamics/skyactive/interview/gvc/01/ Mazda has introduced passenger cars with GVC by engine torque control into real market

Measured data during Journalists test drive events EVALUATION BY JOURNALISTS : STRAIGHT AHEAD DRIVING AT 80KPH  Driver continuously modulates steering wheel angle to keep straight ahead. With GVC With GVC Driver B Driver A Without GVC Without GVC With GVC With GVC Without GVC Without GVC

Measured data during Journalists test drive events EVALUATION BY JOURNALISTS : STRAIGHT AHEAD DRIVING AT 80KPH  Driver continuously modulates steering wheel angle to keep straight ahead. With GVC With GVC Driver C Driver D Without GVC Without GVC With GVC With GVC Without GVC Without GVC

Published at JSAE's annual technical meeting EVALUATION BY JOURNALISTS : STRAIGHT AHEAD DRIVING AT 80KPH  Steering correction (standard deviation) reduces with most of the drivers due to GVC.  Subjective comments by the drivers are; “Increased controllability in small steering operation” - “More planted feel at straight ahead driving“ - “Look - ahead distance has naturally increased“ -  GVC improves handling quality by responding to subtle steering operation.

Driver Model Based Handling Quality Evaluation Method Subjective evaluation Objective and quantitative evaluation

Driver model for lane change Y   L  Objective path y y 0 X L Driver  y y     s h ( 1 s ) e + L 0 + h  h Vehicle - -  1 T s h L

Simplified driver model for sudden lane change on straight road with constant lane width Steering angle 𝜀 ℎ Course deviation  h  h        y 1 s y 1 s L 0 h L 3 driver handling parameters to be identified

Driver parameter identification Find 𝝊 𝑴 ， 𝒊 ， 𝝊 𝒊 to minimize the error here Simple driver model Steering angle 𝜀 ℎ Current lateral Target lateral displacement Deviation of course displacement Driver parameters displacement[m] 𝝊 𝑴 : Response delay time [s] SWA[deg] 𝝊 𝒊 : Preview time [s] Lateral 𝒊 : Control gain[-] Time[s] 13 Measured time history of vehicle motion

Finding driver handling parameters  h  h        y 1 s y 1 s L 0 h L           ( 1 ) ( 1 ) s h s y y L h h L 0 Calculated steering angle by driver model Measured real steering angle using measured vehicle lateral position            ( 1 s ) h ( 1 s ) y y Error L h h L 0  d dy   T           2 2 h J dt [ h ( y y ) h ] dt 0 h L L h dt dt 0   Finding the driver steer parameters, , to minimize J h , and h L    J J J    0 , 0 , 0      h ( h ) h L

Relationships between handling quality and driver parameter Steering angle 𝜀 ℎ Current lateral Target lateral displacement Deviation of course displacement 𝜐 𝑀 : All the response delay of the driver during the lane change Slow, relaxed If 𝜐 𝑀 is large is enough behavior to complete lane change with ease Driving with a margin, Higher handling easier quality evaluation The handling quality evaluation is quantified objectively by the parameter value of 𝜐 𝑀 . 15

Some Examples of Reflections of Vehicle Response Characteristics to Driver Parameter  L – Handling Quality Evaluation

Relation of vehicle response parameters,  n and  , to handling quality evaluation Airplane short period mode of longitudinal response q ( s ) G    2 ( s ) 2 s s   1   2 n n Pilot rating on the longitudinal response Short period natural frequency acceptable good good poor poor good poor poor unacceptable Short period damping ratio

Road vehicle side-slip and yaw rate responses   1 T s ( s )    G ( 0 )    2 2 s s ( s )   1   2 n n  r ( s ) 1 T s  r r G ( 0 )    2 2 s s ( s )   1   2 n n

Vehicle responses to front steer input are rewritten as:     1 T s 1 T s     r f    r f r ( s ) G ( 0 ) ( s ) ( s ) ( s ) G ( 0 ) (s) (s)     h   2 h 2 2 s s 2 s s     h h 1 1     2 2 n n n n If front wheel active steer is set as follows:  2 2 s s   1    2  f n n ( s )   * 2 2 s s   h 1   * * 2 n n Variable response parameter vehicle in denominator,  n * and  * is available from just above front wheel active steer only as follows:    1 T s ( s ) r ( s ) 1 T s     r r G ( 0 ) ( 0 ) G       * 2 * 2 ( s ) 2 s s ( ) 2 s s s     h 1 1   * *   2 * * 2 n n n n

             * * If ( 1 ), (1 ) where , 1.0 1 n n 2 1 2  2 1   2 1 s s    2   1  f n n then s     2 ( 1 ) 1 n   2 1 1 s s h       2 2 ( 1 ) ( 1 ) n 2 n 2  2 1   2 1 s s   2 1  n n   2 1 2 2 n         2 2 1 s s ( ) s s     1 2 2 2 2 n n n n      2 1          s s     1 2 2     1   n n 1    2 1 n   2  1 s s    2     Active steer part n n Direct steer part by driver

Driving simulator with external motion control for variable response parameter vehicle      2 1           s s      1 2 2 h   1     n n ( s ) 1     2 1 n   2  1 s s  V h   2     n n External motion Control System   f r variable stability vehicle

Frequency response of driving simulator with variable response parameter at V=80km/h Yaw rate Lateral acceleration

Lane change test 3.0m 3.0m 80[km/h] 2.5m 3.0m 45[m] 3.0m

Lateral acceleration (m/s 2 ) 15 0.5 0.4 10 Yaw rate (deg/s) 0.3 measured measured 0.2 5 0.1 0 0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 -0.1 -5 -0.2 calculated calculated -0.3 -10 -0.4 -15 -0.5 Calculated motion in driving simulator and measured motions of moving base