| The ride comfort is one of the most important criteria in the market. As aresult, the noise, vibration and harshness (NVH) characteristics are seriouslytaken into account in designing an automobile. As the same time, customers wantto reduce the expenditure on their cars, and governments want to control the airpollution from cars, so there is a strong requirement for fuel efficiency. Toimprove fuel efficiency, makers are trying to improve engine performance and tocut down the weight of automobiles, but there measures are harmful to the NVHcharacteristics.Engines are one of the most important sources of noise and vibration inautomobiles, so the isolation of engine vibration is critical to the improvement ofNVH characteristics. Mount is a bridge that connects engine with chassis. Highperformance engine mounts can not only reduce the vibration that is transmittedby the engine to the vehicle chassis, eliminate "booming"sound inside the vehicleinterior, but also provide the engine-transmission assembly superior protection.The primary function of engine mounts is to support the weight of the engine,and effectively isolate the vibration. Conventional elastomeric mounts andhydraulic mounts are unable to satisfy these two aspects synchronously, onesolution to this problem is active mounts. At present many motor corporation andR&D institution pay attention to the research and design of active engine mounts.The active control hydraulic mount with electromagnetic-actuator researchedin this paper consists of intrinsic passive hydraulic mount andelectromagnetic-actuator. Because hydraulic mounts have superior isolationability in the low frequency range, and electromagnetic actuator can providefavorable active vibration control performance in relative high frequency range,so the active engine mount can isolation the vibration of engine in much widerfrequency range.First, this paper introduces the history of mounts, based on large amount ofinternal and external thesis. The representative structures of different activemounts have been introduced in detail, and the advantage and disadvantage ofdifferent type mount have been list. From the history of mount, we can know thatthere is an trend to use active engine mounts with good performance. Secondly, several different actuators have been introduced in the activevibration control, and the advantage and disadvantage of different type actuatorshave been listed. Electromagnetic actuators satisfy the requirements of the activeengine mount. Because the voice coil actuators are compact, have a highfrequency bandwidth and generate a force outputs linearly proportional to inputcurrent. The characteristics of electromagnetic actuators is studied, and on thephysical model and mathematic model is built, and then the performance issimulated in Matlab, we can find out that voice coil actuators can generate a forceoutputs linearly proportional to input current from the result of simulation. Inorder to design of actuators and selection of parameters, the key factors thatinfluence actuator's performance is analyzed. The control schemes for active vibration isolation can be classified into twocategories: feedback and feedforword controllers. The advantage anddisadvantage of different schemes have been analyzed. The feedforwardcontrollers are generally accepted to be more advantageous in active vibrationcontrol. However, parameters of system vary from system and change accordingto the ageing of system. So an adaptive nature is introduced to feedforwordcontrollers to resolve this problem because it enables the feedforward controllersto adjust themselves according to such variations. The filtered-X LMS algorithmis adopted for its simple structure and good performance. As the same time, thedevelopment and improvement of LMS algorithm is introduced in detail. Thecharacteristics and stability of the LMS algorithm is analyzed. The reason for engine vibration is analyzed, and the design theory andstructure of the active engine mount with electromagnetic-actuator have been...
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