Cryogenic wind tunnel is a sophisticated aerodynamics ground test facility, which operates in cryogenic temperature with injection of liquid nitrogen. The multi-variable, nonlinear and coupled dynamics existing between the temperature, pressure and Mach number in the tunnel, poses great challenges for the effective control of the tunnel. L1 adaptive control is a new control methodology developed in recent years with good robustness properties, which has good potentials to address these challenges. But this control method does not provide full adaptive feedforward control in its generic structure. In the paper, adaptive feedforward control action is introduced into the standard L1 adaptive control architecture for nonlinear systems in the presence of matched un-modeled dynamics. This new control structure is applied to the stagnation pressure control in a cryogenic wind tunnel, which could also be used for the control of temperature and Mach number in the tunnel. This new method could effectively compensate known disturbances with linear gain uncertainty, which occur in the nonlinear systems, while retaining the closed-loop control performance of L1 adaptive control. After the proof and discussions on the stability of this method, simulations of the stagnation pressure control in the wind tunnel are presented. The results and analysis demonstrate the effectiveness of the proposed control architecture.

中文翻译：

---

低温风洞中滞流压力的非线性L ₁自适应控制

低温风洞是一种先进的空气动力学地面测试设备，可在低温下注入液氮来运行。隧道中温度，压力和马赫数之间存在多变量，非线性和耦合动力学特性，对隧道的有效控制提出了巨大挑战。L1自适应控制是近年来开发的一种具有良好鲁棒性的新控制方法，具有解决这些挑战的良好潜力。但是这种控制方法在其通用结构中不能提供完全的自适应前馈控制。在本文中，在存在匹配的未建模动力学的情况下，将自适应前馈控制作用引入到非线性系统的标准L1自适应控制体系结构中。这种新的控制结构适用于低温风洞中的停滞压力控制，也可用于控制隧道中的温度和马赫数。这种新方法可以有效地补偿非线性系统中发生的具有线性增益不确定性的已知扰动，同时保持L1自适应控制的闭环控制性能。在证明和讨论了该方法的稳定性之后，给出了风洞中停滞压力控制的仿真。结果和分析证明了所提出的控制体系结构的有效性。发生在非线性系统中，同时保留了L1自适应控制的闭环控制性能。在证明和讨论了该方法的稳定性之后，给出了风洞中停滞压力控制的仿真。结果和分析证明了所提出的控制体系结构的有效性。发生在非线性系统中，同时保留了L1自适应控制的闭环控制性能。在证明和讨论了该方法的稳定性之后，给出了风洞中停滞压力控制的仿真。结果和分析证明了所提出的控制体系结构的有效性。