| Automotive Powertrain is one of the main excitation sources of vehicle vibration,so the effective vibration isolation of automotive powertrain has great significance toimprove NVH performance of vehicle. The ideal characteristic of powertrain mount isthat its dynamic stiffness and damping is variable with the change of excitationfrequency and amplitude. Traditional passive mount is difficult to meet vibrationisolation requirements in broadband frequency. In order to achieve the effectiveisolation of the powertrain mount in broadband frequency, the research of semi-activecontrol method and its control system based on the magneto-rheological(MR) mount iscarried out.The three degree-of-freedom dynamic model of the powertrain mounting systemhas been built, then fuzzy controller is designed and the simulation analysis of thecontrol method is processed. The simulation results indicate that fuzzy controller canreduce the force transmission rate within resonance frequency band, and the highfrequency band is improved slightly.For the requirements of control system with MR mount, the modular designconcept is applied to design the hardware circuit of control system. After making thePCB circuit, the functional testing of hardware system is processed. The results showthat the controller has function of CAN communication and SCI communication; Thedriver circuit is of the ability of outputing0~1.5A continuously variable current; Thepeak-to-peak value of current ripple is less than50mA and the response speed ofcurrent step change is less than3ms, so the design results could meet the requirementsof control system.Based on the implementation of hardware system, taking into account thereal-time requirements of control system and micro-kernel of embedded real-timeoperating system, μC/OS-II is transplanted into the target MCU, and testing cases iswrited to test the system. The results show that the scheduling service of μC/OS-II coreis normal; communication mechanism can be used normally; μC/OS-II has beenrunning correctly on the target MCU.According to a tiered software design idea, overall analysis of software system isprocessed based on the kernel service of μC/OS-II, On the basis of which, thedriver-layer and application-layer program are designed specifically. Finally, the unit, module and integration testing for the software system are carried out. Software testingresults indicate that the MR mounting control system is adequately suitable for thepowertrain mounting system and could show better real-time performance. |
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