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Initial Pitch Control for Semi-active Suspension System
Abstract:
The aim of this study is to develop an Add-On Feature that could support the
semi-active suspension system controller during longitudinal dynamics maneuvers.
The Add-On Feature called Initial Pitch Control (IPC) is activated during
launching, shifting, and braking to enhance the pitch motion characteristics and
road-holding capability. A sixteen degrees-of-freedom (DoF) vehicle mathematical
model represents the vertical and longitudinal dynamics developed and validated
via laboratory and road tests. A hydraulic four-poster test rig is used to carry
out the laboratory tests for the vertical dynamics verification, while the
longitudinal dynamic verification is achieved through the performed tests on a
highway track. In order to design the IPC algorithm, the Rule-Optimized (RO)
semi-active suspension controller, an Anti-lock Braking System (ABS) controller,
and seven gears Dual-Clutch Transmission (DCT) controller are implemented in the
vehicle model. An optimization routine has been applied to find the optimum
force gains for the IPC algorithm. The IPC algorithm is evaluated in terms of
the body pitching motion and the road holding during launching and braking.
Comparisons between the passive suspension and semi-active suspension systems
with and without the proposed IPC algorithm have been performed. The obtained
results illustrated that the IPC algorithm with the semi-active controller
improved both the pitching motion and road-holding characteristics of the
vehicle compared with the passive suspension system and semi-active suspension
without IPC.