Torsional vibration generated during operation of commercial vehicles can
negatively affect the life of driveline components, including the transmission,
driveshafts, and rear axle. Undesirable vibrations typically stem from
off-specification parts, or excitation at one or more system resonant
frequencies. The solution for the former involves getting the system components
within specification. As for the latter, the solution involves avoiding
excitation at resonance, or modifying the parameters to move the system’s
resonant frequencies outside the range of operation through component changes
that modify one, or more, component inertia, stiffness, or damping
characteristics. One goal of the effort described in this article is to propose,
and experimentally demonstrate, a physics-based gear-shifting algorithm that
prevents excitation of the system’s resonant frequency if it lies in the
vehicle’s range of operation. To guide that effort, analysis was conducted with
a numerical simulation model incorporating nonlinear driveline dynamics
resulting from engine operation (including misfire and cylinder deactivation),
excitation from multiple universal joints, the transmission, and a vehicle speed
feedback controller, a contribution the authors have not seen in the
pre-existing literature. The experimentally validated simulation results
demonstrate that the torsional oscillating mode corresponding to the torque
converter or turbine exhibits sensitivity to clutch activation, and variations
in system parameters. Consequently, variation in system parameters alters the
natural frequency of the system, potentially aligning it with the vehicle’s
operational frequency range in specific gear ranges. Experimental on-road tests,
described here, demonstrate that for the truck-under-test one of the natural
frequencies of the system is within the range of operation for gears 4, 5, and 6
for certain vehicle speeds. Resonance in these gears was successfully prevented,
and experimentally demonstrated, by using the proposed algorithm without
sacrificing the performance of the vehicle.
