摘要：
To improve a SUV's ride quality and mobility,etc.,an electronic control unit of electronically controlled air suspensions (ECAS) was designed by using a Freescale XDT512 microcontroller,which consisted of a minimum system,a power source module,a driving module,a speed signal processing module,a double acceleration module,an analog signal processing module,a communication module and so on.The control strategy model of an ECAS system was designed by using the model-based design method,which included an auto-mode sub_model,a manual-model sub_model and a repair-mode sub_model.The height of the car can be automatically adjusted according to the speed in auto-mode,and a driver can freely set the height of the car by using a human-machine interface in manual-mode.In repair-mode,the functions of the ECAS system were disabled to prevent any unexpected action.The structural test and functional test were conducted after a set of test cases were properly designed.When fixed-point treatment was conducted,the control model was converted into an application program by using RTW technologies,and then it was integrated with low-level driven programs,the final integrated program was downloaded into the electronic control unit of an ECAS.Then vehicle experiments were carried out,the results of experiments showed that the proposed control strategy fulfilled the design requirements.%设计了以Freescale XDT512为核心芯片,且由最小系统、电源模块、驱动电路、速度处理模块、两向加速度模块、模拟量输入模块和通信模块等组成的电控空气悬架系统(ECAS)电子控制单元;利用基于模型的设计方法开发了电控空气悬架系统的控制策略模型,其主要由自动模式子模块、手动模式子模型和维修模式子模型等组成;在自动模式下,根据车速自动调整车身高度;在手动模式下,驾驶员可通过人机操控界面,自主地设定车身高度;通过维修模式,可禁止电控空气悬架工作,防止出现误动作.通过合理设计测试用例对所设计的控制模型实施结构性、功能性测试;经控制模型的定点化处理,并利用RTW代码生成技术将所设计的控制模型转换为应用层程序,并与底层驱动相互集成后,编译下载至所开发的ECAS电子控制单元;开展实车验证试验,试验结果表明所设计的控制策略能较好地满足设计要求.
