压电快反镜(Piezoelectric Fast Steering Mirror,PFSM)固有的迟滞特性严重制约了其在精密定位系统中的控制精度。为此,从时间复杂度、求逆必要条件及误差来源3个核心维度,系统对比了常见包络函数的性能差异,综合性选取了非对称线性包...压电快反镜(Piezoelectric Fast Steering Mirror,PFSM)固有的迟滞特性严重制约了其在精密定位系统中的控制精度。为此,从时间复杂度、求逆必要条件及误差来源3个核心维度,系统对比了常见包络函数的性能差异,综合性选取了非对称线性包络函数,采用了基于非对称线性包络函数的率相关广义Prandtl-Ishlinskii模型(Rate-Dependent General⁃ized Prandtl-Ishlinskii Model with Asymmetric Linear Envelope Function,LRGPI)。为解决迟滞的率相关问题,引入导数项拓宽了模型的适用频率范围。随后,构建LRGPI逆模型前馈,对比验证迟滞补偿的有效性。最后,设计基于逆模型前馈的复合控制方法,抑制外界干扰的影响。仿真实验表明,LRGPI逆模型前馈控制相较于基于tanh包络函数的率相关广义PI(Tanh Envelope-Based Rate-Dependent Generalized Prandtl-Ishlinskii Model,TRGPI)逆模型和基于三次项包络函数的率相关广义PI(Cubic Envelope-Based Rate-Dependent Generalized Prandtl-Ishlinskii Model,CRGPI)逆模型,迟滞补偿的带宽分别提高了5.78%和28.69%。基于逆模型前馈补偿的对比实验进一步表明,LRGPI逆模型前馈控制的RMSE相比PI逆模型、TRGPI和CRGPI逆模型分别减少了62.7%,23.2%和26.4%,充分证明LRGPI模型在解决PF⁃SM的迟滞行为方面具有显著的优越性和稳定性。展开更多
When the stagnation temperature of a perfect gas increases, the specific heat ratio does not remain constant any more, and start to vary with this temperature. The gas remains perfect, its state equation remains alway...When the stagnation temperature of a perfect gas increases, the specific heat ratio does not remain constant any more, and start to vary with this temperature. The gas remains perfect, its state equation remains always valid, except it will name in more calorically imperfect gas or gas at High Temperature. The goal of this work is to trace the profiles of the supersonic Minimum Length Nozzle with centered expansion when the stagnation temperature is taken into account, lower than the threshold of dissociation of the molecules and to have for each exit Mach number several nozzles shapes by changing the value of the temperature. The method of characteristics is used with a new form of the Prandtl Meyer function at high temperature. The resolution of the obtained equations is done by the second order of fmite differences method by using the predictor corrector algorithm. A study on the error given by the perfect gas model compared to our model is presented. The comparison is made with a calorically perfect gas for goal to give a limit of application of this model. The application is for the air.展开更多
文摘When the stagnation temperature of a perfect gas increases, the specific heat ratio does not remain constant any more, and start to vary with this temperature. The gas remains perfect, its state equation remains always valid, except it will name in more calorically imperfect gas or gas at High Temperature. The goal of this work is to trace the profiles of the supersonic Minimum Length Nozzle with centered expansion when the stagnation temperature is taken into account, lower than the threshold of dissociation of the molecules and to have for each exit Mach number several nozzles shapes by changing the value of the temperature. The method of characteristics is used with a new form of the Prandtl Meyer function at high temperature. The resolution of the obtained equations is done by the second order of fmite differences method by using the predictor corrector algorithm. A study on the error given by the perfect gas model compared to our model is presented. The comparison is made with a calorically perfect gas for goal to give a limit of application of this model. The application is for the air.
