Effective control of ride quality and handling performance are challenges for active vehicle suspension systems, particularly for off-road applications. Off-road vehicles experience large suspension displacements, where the nonlinear kinematics and damping characteristics of suspension elements are significant. These nonlinearities tend to degrade the performance of active suspension systems, introducing harshness to the ride quality and reducing off-road mobility. Typical control strategies rely on linear, time-invariant models of the suspension dynamics. While these models are convenient, nominally accurate, and tractable due to the abundance of linear control techniques, they neglect the nonlinearities and time-varying dynamics present in real suspension systems. One approach to improving the effectiveness of active vehicle suspension systems, while preserving the benefits of linear control techniques, is to identify and cancel these nonlinearities using Feedback Linearization. In this paper the authors demonstrate an intelligent parameter estimation approach using structured artificial neural networks that continually “learns” the nonlinear parameter variations of a quarter-car suspension model. This estimation algorithm becomes the foundation for an Intelligent Feedback Linearization (IFL) controller for active vehicle suspensions. Results are presented for computer simulations, real-time experimental tests, and field evaluations using an off-road vehicle (a military HMMWV). Experimental results for a quarter-car test rig demonstrate 60% improvements in ride quality relative to baseline (non-adapting) control algorithms. Field trial results reveal 95% reductions in absorbed power and 65% reductions in peak sprung mass acceleration using this IFL approach versus conventional passive suspensions.

1.
Beno, J. H., Bresie, D. A., Ingram, S. K., Weeks, D. A., and Weldon, Wm. F., 1995, “Electromechanical Suspension System,” Final Report to U. S. Army Tank and Automotive Command, Warren, MI, June.
2.
Weeks, D. A., Beno, J. H., Guenin, A., and Bresie, D. A., 1999, “The Design of an Electromagnetic Linear Actuator for an Active suspension,” SP-1438, Steering and Suspension Technology Symposium 1999, SAE, Warren, MI.
3.
Crosby, M., and Karnopp, D. C., 1973, “The Active Damper—A New Concept for Shock and Vibration Control,” Shock and Vibration Bulletin, Part H.
4.
Hrovat
,
D.
,
1997
, “
Survey of Advanced Suspension Developments and Related Optimal Control Applications
,”
Automatica
33
, No.
10
, pp.
1781
1817
.
5.
Kim, E. S., 1996, “Nonlinear Indirect Adaptive Control of a Quarter Car Active Suspension,” Proceedings of the 1996 IEEE International Conference on Control Applications, pp. 61–66.
6.
Williams, D. E., and Haddad, W. M., “Active Suspension Control to Improve Vehicle Ride and Handling,” Vehicle System Dynamics 28, No. 1, pp. 1–24.
7.
Moran
,
A.
, and
Nagai
,
M.
,
1994
, “
Optimal Active Control of Nonlinear Vehicle Suspensions Using Neural Networks
,”
JSME International Journal, Series C
37
, No.
4
, pp.
707
719
.
8.
Nagai
,
M.
,
Moran
,
A.
,
Tamura
,
Y.
, and
Koizumi
,
S.
,
1997
, “
Identification and Control of Nonlinear Active Pneumatic Suspension for Railway Vehicles, Using Neural Networks
,”
Control Engineering Practice
5
, No.
8
, pp.
1137
1144
.
9.
Scheutze, K. T., Beno, J. H., Weldon, W. F., and Sreenivasan, S. V., 1998, “A Comparison of Controller Designs for an Active, Electromagnetic, Offroad Vehicle Suspension System Traveling at High Speed,” presented at the SAE International Congress and Exposition, Detroit, MI, Feb. 23–26.
10.
Sunwoo, M., and Cheok, K. C., 1991, “Investigation of Adaptive Control Approaches for Vehicle Active Suspension Systems,” Proceedings of 1991 American Control Conference, Vol. 2, pp. 1542–1547.
11.
Weeks, D. A., Beno, J. H., Bresie, D. A., and Guenin, A. M., 1997, “Control System for Single Wheel Station Tracked Vehicle Active Electromagnetic Suspension,” presented at SAE International Congress and Exposition, Detroit, MI, Feb.
12.
Weeks, D. A., Beno, J. H., Bresie, D. A., and Guenin, A. M., 1997, “Laboratory Testing of Active Electromagnetic Near Constant Force Suspension (NCFS) Concept on Subscale Four Corner, Full Vehicle Test-Rig,” presented SAE International Congress and Exposition, Detroit, MI, February 24–27.
13.
Ljung, L., 1991, “Issues in System Identification,” IEEE Control Syst. Mag., pp. 25–29.
14.
Ljung, L. and Glad, T., 1994, Modeling of Dynamics Systems, Prentice Hall.
15.
A˚stro¨m, K. J., and Wittenmark, B., 1995, Adaptive Control, 2nd Ed., Addison Wesley.
16.
G. C. Merriam Co., 1991, Webster’s New Collegiate Dictionary, G. C. Merriam Co.
17.
Haykin, S., 1994, Neural Networks, A Comprehensive Foundation, Prentice Hall.
18.
Cybenko, G., 1989, “Approximations by Superpositions of a Sigmoidal Functions,” Mathematics of Control Signal Systems 2 pp. 303–314.
19.
Hornik
,
J.
,
Stinchcombe
,
M.
, and
White
,
H.
,
1989
, “
Multilayer Feedforward Networks are Universal Approximators
,”
Neural Networks
2
, pp.
359
366
.
20.
Baker, W. L., and Farrell, J. A., 1992, An Introduction to Connectionist Learning Control Systems, Handbook of Intelligent Control: Neural, Fuzzy, and Adaptive Approaches, Van Nostrand Reinhold.
21.
Slotine, J. J., and Li, W., 1991, Applied Nonlinear Control, Prentice Hall.
22.
Brogan, W. L., 1991, Modern Control Theory, 3rd ed., Prentice Hall.
23.
Bruzzone
,
L.
,
Roli
,
F.
, and
Serpico
,
S. B.
,
1998
, “
Structured Neural Networks for Signal Classification
,”
Signal Process.
64
, No.
3
, pp.
271
290
.
24.
Bastow, D., and Howard, G. P., 1993, Car Suspension and Handling, 3rd Ed., Society of Automotive Engineers, Inc.
25.
Wong, J. Y., 1993, Theory of Ground Vehicles, Wiley, New York, NY.
26.
Buckner, G. D., and Schuetze, K. T., 1999, “Intelligent Estimation of System Parameters for Active Vehicle Suspension Control” SP-1438, Steering and Suspension Technology Symposium 1999, SAE, Warren, MI.
27.
Buckner, G. D., Schuetze, K. T., and Beno, J., 2000, “Active Vehicle Suspension Control Using Intelligent Feedback Linearization,” American Control Conference, Chicago, IL, June.
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