基于液晶相控阵的光束偏转控制方法研究

液晶相控阵作为一种新型的可编程相位调制器件,可实现小角度范围内的光束偏转。但由于液晶相控阵制作工艺难度大、且受温度及大气扰动等影响,使得光束偏转系统实际偏转角与预期偏转角之间存在一定误差。为了提高液晶相控阵光束偏转精度,本文提出了一种基于分数阶PI~λD~μ控制器的光束偏转闭环控制回路。CCD作为探测元件,接收待测物体漫反射回来的光。采用斜射式三角测量法,计算预期偏转角与实际偏转角的偏转误差。将误差信号输入到分数阶PI~λD~μ控制器,控制器生成控制信号传给被控对象液晶相控阵,最终实现光束精确偏转。经仿真实验和性能分析,系统阶跃响应测试经过2步迭代达到稳定输出状态,闭环带宽为7.67rad/s,对幅值为1、频率为1的正弦扰动信号系统抑制比为-18.06dB。验证了分数阶PI~λD~μ控制算法能够快速地抑制扰动和噪声,且扰动抑制效果好,稳定性高。

Beam deflection control method based on liquid crystal phased array

As a novel programmable phase modulation device, the liquid crystal phased array can realize beam deflection in a small angle range. However, due to the influence of manufacturing process, temperature and atmospheric disturbances, there is a certain error between the actual and the expected deflection angle of the beam deflection system. In order to make beam deflection more accurate, this paper proposes a closed-loop control loop for beam deflection based on fractional-order-controller. As the detection element, CCD receives the light diffusely reflected from measured object, adopting oblique triangulation to calculate the deflection error between the expected and the actual deflection angle. Then the error signal is transmitted to controller,the generated control signal will be sent to the controlled object-liquid crystal phased array, to achieve accurate beam deflection. Through simulation experiments and performance analysis, the system step response test reach a steady output state after two iterations. The closed-loop bandwidth is 7.67 rad/s, the suppression ratio of the sinusoidal disturbance signal system with amplitude 1 and frequency 1 is -18.06 dB. It is verified that the fractional-order-control algorithm can quickly suppress the disturbance and noise, furtherly, the disturbance suppression effect is good and the stability is high.