Semi-active and active control of frame vibration in automotive vehicles

The feasibility of reducing frame vibrations in automotive vehicles with controlled hydraulic engine mounts is investigated. Only engine idle situations are considered. Two modes of control are studied: semi-active and active. A dynamic model is developed for the semi-active hydraulic mount. The model is verified experimentally through impedance measurements. Sensitivity studies reveal the effectiveness of various parameter control schemes. Experimental implementation of the semi-active hydraulic mounts on a commercial vehicle confirm their ability to reduce frame vibration levels at engine idle speeds. A simplified vehicle system model is used to investigate frame vibration control with active engine mounts. Closed-loop control designs using variations of the LQG control design method are evaluated through simulations. A method referred to as Gain-Sensitivity Augmentation (GSA) is developed to permit LQG controller adaptation to structured plant parameter perturbations. The GSA method is applied to the application problem. Improved LQG control performance is achieved with the GSA method