基于PLC的液体培养基自动制备系统设计

针对液体培养基人工制备过程低效且目前国内外缺乏具有完整流程的液体培养基自动制备系统的问题，开发了一套基于可编程逻辑控制器（programmable logic controller， PLC）的液体培养基自动制备系统，其选用动作与感知层、传输层和应用层相结合的架构体系，由进料子系统、出料子系统和控制子系统组成。该系统以PLC、MCGS（monitor and control generated system，监视与控制通用系统）触摸屏、传感器和执行设备组合的方式，实现基于培养基配方的组分全自动选择和配比，在线pH监控和溶解氧（dissolved oxygen， DO）监测，以及全自动清洗、过滤、混匀和分装，完成液体培养基的自动配制。同时，监控数据可实时采集和图形化显示，且全流程可回溯、可存储。针对系统的误差，基于试验数据获得误差模型后通过预测确定误差修正量。经实际测试与修正，所设计系统制备液体培养基的相对误差在0.336%以下，重复性误差在0.274%以下，pH的最大控制误差为±0.18，pH和DO的最大测量误差分别为±0.04和±1%，能够满足液体培养基的制备需求。研究结果对全流程自动化液体培养基制备系统的开发有一定的参考意义。

Design of automatic preparation system of liquid culture medium based on PLC

Aiming at the problems of low efficiency of manual preparation process of liquid culture medium and lack of automatic preparation system of liquid culture medium with complete process at home and abroad, an automatic preparation system of liquid culture medium based on programmable logic controller (PLC) was developed, which used the architecture that combined with action and perception layer, transmission layer and application layer, and consisted of feeding subsystem, discharging subsystem and control subsystem. The system realized the automatic selection and proportion of components based on the culture medium formula, online pH monitoring and dissolved oxygen (DO) monitoring, as well as the automatic cleaning, filtering, mixing and subpackaging of liquid culture medium through the combination of PLC, MCGS (monitor and control generated system) touch screen, sensors and execution equipment. At the same time, the monitoring data could be collected in real time and displayed graphically, and its whole process could be traced and stored. For the system error, the error model was obtained based on the test data, and the error correction was determined through prediction. Through actual test and correction, the relative error of the designed system for preparing liquid culture medium was below 0.336%, the repeatability error was below 0.274%, the maximum control error of pH was ±0.18, the maximum measurement error of pH and DO was ±0.04 and ±1%, which met the preparation requirements of liquid culture medium. The research results have certain reference significance for the development of the whole process automatic liquid medium preparation system.