Robust Position Sensing and Control for Planar Linear Motors

9523156霍利斯平面直线电机，通常被称为施力器，在几乎没有运动部件的大型工作空间中提供低摩擦运动。由于它们作为开环步进器运行，它们容易失步，受外部干扰影响，不能提供可控力或高刚性。如果有可靠且不显眼的位置传感器，反馈控制可以弥补这些不足。这个项目将研究两种用于平面电机系统的隐蔽传感技术，定位分辨率为1微米。一种提出的传感器使用交流磁场驱动磁通来在安装压板上的传感齿中感应磁场。另一种方法也使用压板齿，但基于光学原理。当涂有荧光染料材料的牙齿被一种波长的光照射时，它会发出更长波长的光；这种第二波长的强度是位置的函数。这两个传感器的研究问题是空间和时间噪声、串扰和传感器-作用力的集成。利用这些传感器，将设计一种基于模型的变结构鲁棒控制方案，以处理非线性磁场、有效载荷效应和模型不确定性。这项研究将提高平面直线电机的速度和有效载荷，使其成为下一代机器和设备的致动器，这些机器和设备需要在大的平面工作空间上定位一微米。***

9523156 Hollis Planar linear motors, often called forcers, provide low friction motion in a large workspace with few moving parts. Because they operate as open loop steppers, they are: susceptible to losing steps, affected by external disturbances, and cannot provide controlled forces or high stiffness. Feedback control can compensate for these deficiencies if reliable and unobtrusive position sensors are available. This project will investigate two unobtrusive sensing techniques for planar motor systems with 1 micrometer positioning resolution. One proposed sensor uses the AC magnetic field drive flux to induce a field in a sensing tooth on the mounting platen. The other approach also uses platen teeth, but is based on optics. A when a tooth coated with a florescent dye material is illuminated by light of one wavelength, it emits light at a longer wavelength; the intensity of this secondary wavelength is function of position. Research issues for both sensors are spatial and temporal noise, cross talk, and sensor-forcer integration. Using these sensors, a model based and a variable structure robust control scheme will be designed to deal with nonlinear magnetic fields, payload effects and model uncertainties. This research will enable increases in speed and payload for planar linear motors, making them attractive as actuators for next generation machines and equipment that need one micrometer positioning over a large planar workspace. ***