陀螺稳定平台速度环的离散模型参考自适应控制

A Discrete-time Model Reference Adaptive Control for Velocity Loop in a Gyro-stabilized Platform

在建立两轴四框架陀螺稳定平台内方位速度环的非线性模型,并对非线性摩擦力进行前馈补偿的基础上,将模型参考自适应控制理论引入到陀螺稳定平台的系统控制中.根据控制系统结构、输入/输出关系以及广义输出误差建立了离散模型参考自适应控制系统;推导出带有可调函数的自适应控制器;针对可调函数的分母有可能出现接近于零或为零值而导致可调函数值非常大甚至无穷大的情况,提出了一种通过对分母采用阈值限制,使分母在小于阈值的情况下采用上一时刻函数值的改进方法.对所提出的控制器的优越性进行了性能对比实验:在非线性摩擦力前馈补偿不充分的情况下,分别采用所提出的模型参考自适应控制和比例—积分(PI)控制进行系统仿真的性能对比实验及其实验结果的对比分析.本文为进一步提高陀螺稳定平台的控制性能,提供了一种新的高精度的控制策略.

Based on the nonlinear velocity loop model for a four-gimbal, two-axis, gyro-stabilized platform and the feed-forward compensation of nonlinear friction torque, a model reference adaptive control is introduced for a gyro-stabilized platform system. Based on the control system structure and the relationship between the input and output as well as the generalized output error, a discrete model reference adaptive control system is established, and an adaptive controller with adjustable functionality is derived. To solve the problem of large or in- finite adjustable functions when the denominator is zero or near-zero, the method is improved by using the last time value of the function when the denominator is less than the preset threshold. To demonstrate the superiority of the proposed controller, experiments are conducted to compare the performance of the model reference adaptive control system and the PI control system. The experimental results are analyzed to ensure that the non- linear friction torque is sufficiently compensated. A new high-precision control strategy is proposed to further improve the control performance of the gyro-stabilized platform.