The variable displacement technology developed to improve the fuel efficiency engine system is going to be widely adopted because fossil fuels are in danger of running out. VCM (Variable Cylinder Management) Engine, one of the various adaptations of variable displacement technology, makes 2 or 3 cylinders be deactivated when driving at constant speed or on a downhill road. If the chassis vibration originated from the engine oscillation is changed abruptly due to intentional misfiring of cylinders in VCM engine, it can give driver and passenger unpleasant feelings. So we have to make the vibration characteristics be kept unchanged during engine’s operational mode change. There are two additional issues to be investigated for successful application of the proposed method. To improve the control efficiency we have to find minimum energy solution. The other issue is that the transient response should be unnoticeable as the state is changing between two operating modes: normal mode and VCM activated mode.
VCM engine and chassis modeling is constructed based on a full size sedan. In order to minimize the chassis vibration, an open loop control is applied to eliminate the transient feelings and then we propose an adaptive control algorithm after modifying the conventional Filtered-x LMS algorithm to generate the desired vibration characteristics. Structure vibration suppression depends not only on control law design but also on sensor/actuator selection and placement. The location of the active engine mounts on the chassis is found out where we can get the minimum energy and the performance. We minimize the three translational motions at the head rest position since according to research; head vibration is a critical factor in determining the acceptability of whole body vibration. In order to improve the performance a third actuator has been added in Y direction to the third engine mount position, while the first and second actuator are installed in Z direction of the two main engine mounts. Performance has been increased in both cases compared to two actuators’ case; however, power consumption has been increased.
Simulation results show that the proposed method is very effective to eliminate the discomfort caused by the abrupt jerk in transient region and reduce the overall vibration level.
