Combining active structural damping and active suspension control in flexible bodied railway vehicles

There is a desire to design lightweight railway vehicle bodies for future high speed trains. Previously, suppression of structural vibration of the flexible lightweight vehicle body was attempted via use of active suspensions (conventional actuators) or by structural damping via piezoelectric actuators, with the aim being to improve the ride quality. In a railway vehicle the typical active suspension setup comprises front and rear suspension conventional actuators, while adding more macro-actuator elements to minimise structural vibrations can substantially impact vehicle weight and location considerations. In this paper, we show that piezoelectric actuator control can provide complementary action to active suspensions. Decentralized control is adopted for combined active structural damping and active suspension design via Linear Quadratic Gaussian (LQG) method and modal control with skyhook damping respectively. The side-view model of a flexible-bodied railway vehicle integrated with piezoelectric actuators and appropriate sensor outputs is derived and the placement of the piezoelectric actuators and sensors is addressed via structural norms. It is shown that vibrations of both the flexible modes and rigid modes are suppressed effectively. This suggests that with the combined approach, control by both piezoelectric actuators and suspension actuators could be used in a more efficient way to address vibrations in light railway vehicle bodies.