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Abstract: In this study, we developed and tested a high-precision motion trajectory tracking controller of a pneumatic cylinder driven by four costless on/off solenoid valves rather than by a proportional directional control valve. The relationship between the pulse width modulation (PWM) of a signal’s duty cycle and control law was determined experimentally, and a mathematical model of the whole system established. Owing to unknown disturbances and unmodeled dynamics, there are considerable uncertain nonlinearities and parametric uncertainties in this pneumatic system. A modified direct adaptive robust controller (DARC) was constructed to cope with these issues. The controller employs a gradient type adaptation law based on discontinuous projection mapping to guarantee that estimated unknown model parameters stay within a known bounded region, and uses a deterministic robust control strategy to weaken the effects of unmodeled dynamics, disturbances, and parameter estimation errors. By using discontinuous projection mapping, the parameter adaptation law and the robust control law can be synthesized separately. A recursive backstepping technology is applied to account for unmatched model uncertainties. kalman filters were designed separately to estimate the motion states and the derivative of the intermediate control law in synthesizing the deterministic robust control law. Experimental results illustrate the effectiveness of the proposed controller.

用于气动系统的一种改进型直接自适应鲁棒运动跟踪控制器

研究目的：采用直接自适应鲁棒控制器（DARC）时，可使用廉价开关电磁阀实现气动系统高精度运动轨迹跟踪控制。为简化DARC算法，本文提出一种改进型直接自适应鲁棒控制策略（modified DARC）。
创新要点：采用卡尔曼滤波器，估计合成确定性鲁棒控制律时的中间控制率的一阶导数，从而避免求解中间控制率的一阶导数的可计算部分，简化控制算法。
方法提亮：采用基于离散投影的梯度类型的自适应率，以确保估计出的未知模型参数落在已知有界区域内；使用确定性鲁棒控制策略减小未建模动态、扰动以及参数估计误差的影响；使用离散投影图，以同时合成参数自适应律和鲁棒控制律；分别设计卡尔曼滤波器，用于估计运动状态、估计合成确定性鲁棒控制律时的中间控制率的一阶导数。
重要结论：本文提出的改进型自适应鲁棒控制策略，可以简化控制算法。实验结果表明，该策略能实现高精度的运动轨迹跟踪控制，且对扰动有很强的鲁棒性。
开关电磁阀；跟踪控制；鲁棒控制；自适应控制；卡尔曼滤波器；离散投影

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