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TECHNICAL PAPERS

Optimal Control of Restraint Forces in an Automobile Impact

[+] Author and Article Information
Richard W. Kent

Mechanical and Aerospace Engineering Department, University of Virginia, 122 Engineer’s Way, Charlottesville, VA 22904-4746rwk3c@virginia.edu

Dmitry V. Balandin

Department of Computational Mathematics and Cybernetics, Nizhny Novgorod State University, 23 Gagarin Ave., Nizhny Novgorod, 603950, Russiabalandin@pmk.unn.runnet.ru

Nikolai N. Bolotnik

 Institute for Problems in Mechanics of the Russian Academy of Sciences, 101-1, Prosp. Vernadskogo, Moscow, 119526, Russiabolotnik@ipmnet.ru

Walter D. Pilkey1

Mechanical and Aerospace Engineering Department, University of Virginia, 122 Engineer’s Way, Charlottesville, VA 22904-4746wdp@virginia.edu

Sergey V. Purtsezov

Mechanical and Aerospace Engineering Department, University of Virginia, 122 Engineer’s Way, Charlottesville, VA 22904-4746pusv@virginia.edu

1

This author is responsible for correspondence.

J. Dyn. Sys., Meas., Control 129(4), 415-424 (Oct 25, 2006) (10 pages) doi:10.1115/1.2718240 History: Received April 01, 2005; Revised October 25, 2006

This study concerns a concept for an optimal control of the force developed in an automotive restraint system during a frontal impact. The concept is close to that of “smart” restraint systems and involves continuous control of the restraint force by moving the point of attachment of the restraint system to the vehicle or retracting and releasing the seat belts. The analytical foundation for the control of the restraining force does not appear to have been formulated prior to this study. The control design involves the limiting performance analysis of the isolation of an occupant from the crash impact and the formation of a feedback to sustain the open-loop control law that provides the limiting performance. Initially, the problem is outlined using a single-degree-of-freedom system and solved for optimal isolator characteristics. This exercise shows that the optimal force is constant and that the performance of a restraint system behaving as a linear spring is half as effective as the optimal. The methodology is then applied to a published thoracic model having multiple degrees of freedom. A set of functionals is defined as constraints corresponding to injury criteria and the displacement of the occupant relative to the vehicle. The characteristics of the optimal isolator force are then determined. It is shown that this force has a short-duration period of high magnitude early in the profile, followed by an interval of nearly constant force. Next it is shown that a restraint behaving as a linear spring can generate the optimal control force if its attachment point in the vehicle is allowed to move. The design of the control law for this motion involves the determination of an optimal open-loop control and the formation of a feedback to sustain this control. Forms for both of these are presented. A substantial improvement in the behavior of an automobile occupant’s restraint systems can be anticipated from an active control of the seat belt retraction.

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Copyright © 2007 by American Society of Mechanical Engineers
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Figures

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Figure 1

Frontal crash model for thoracic injury

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Figure 2

Optimal (limiting performance) responses to the deceleration pulses of various durations (solid line for Tp=0.08s, dashed line for Tp=0.1s, and dotted line for Tp=0.12s)

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Figure 3

Half-sine deceleration pulses of various durations (solid line for Tp=0.08s, dashed line for Tp=0.1s, and dotted line for Tp=0.12s)

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Figure 4

Time histories of the motion of the restraint system attachment point for various crash pulses (solid line for Tp=0.08s, dashed line for Tp=0.1s, and dotted line for Tp=0.12s)

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Figure 5

The influence of the mismatch between the law of motion of the attachment point and the pulse duration on the response characteristics (solid line for Tp=0.08s, dashed line for Tp=0.1s, and dotted line for Tp=0.12s)

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