力显微镜杠杆的现场可编程门阵列数字控制
Digital control of force microscope cantilevers using a field programmable gate array
摘要：
本文介绍了一种基于现场可编程门阵列（FPGA）的磁共振力显微镜（MRFM）悬臂梁控制器，以及用于将控制器集成到实验中的硬件和软件。该控制器由低成本的商用软件定义无线电（SDR）设备和开源软件库组装而成。该控制器包括一个数字滤波器，该数字滤波器包括两个级联的二阶部分（“双四阶”），它们一起可以实现用于最佳悬臂控制器的传递函数。本报告中的附录显示了如何根据测得的悬臂梁特性计算最优控制器的滤波器系数。控制器还包括用于校准协议的输入多路复用器和加法器。滤波器系数和多路复用器设置可以在实验运行时通过控制软件进行设置和调整。输入以64 MHz采样;滤波器中的采样频率可以在软件控制下分频，以实现与滤波器特性的良好匹配。这里报告的数据是在500 kHz下采样的，选择用于谐振频率接近8 kHz的声学杠杆。输入采用12位分辨率数字化，输出采用14位分辨率数字化。实验软件被组织为客户端和服务器，使其易于适应不同的实验控制器。服务器详细说明了控制器硬件组织、连接技术、过滤器架构和数字表示。相同的服务器可以用于任何实验，而不同的客户端编码每个实验的细节。
英文摘要：
This report describes a cantilever controller for magnetic resonance force microscopy (MRFM) based on a field programmable gate array (FPGA), along with the hardware and software used to integrate the controller into an experiment. The controller is assembled from a low-cost commercially available software defined radio (SDR) device and libraries of open-source software. The controller includes a digital filter comprising two cascaded second-order sections ("biquads"), which together can implement transfer functions for optimal cantilever controllers. An appendix in this report shows how to calculate filter coefficients for an optimal controller from measured cantilever characteristics. The controller also includes an input multiplexer and adder used in calibration protocols. Filter coefficients and multiplexer settings can be set and adjusted by control software while an experiment is running. The input is sampled at 64 MHz; the sampling frequency in the filters can be divided down under software control to achieve a good match with filter characterisics. Data reported here were sampled at 500 kHz, chosen for acoustic cantilevers with resonant frequencies near 8 kHz. Inputs are digitized with 12 bits resolution, outputs with 14 bits. The experiment software is organized as a client and server to make it easy to adapt the controller to different experiments. The server encapusulates the details of controller hardware organization, connection technology, filter architecture, and number representation. The same server could be used in any experiment, while a different client encodes the particulars of each experiment.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
