自动移液设备多轴运动控制系统设计

Design of Multi-Axis Motion Control System for Automatic Pipetting Equipment

摘要: 针对生物医学实验室对低成本、高精度自动化设备的迫切需求，设计并开发了一种基于G-code (G代码)的多轴脉冲时序控制的自动移液系统。系统采用模块化架构，以MKS Monster8 V2为主控制器，搭载定制化Marlin固件，集成6个42步进电机，通过推导脉冲–位移–速度关系并以时间基准计算各轴脉冲频率。软件中计算旋转、升降、移液、XYZ轴移动等多轴的同步插补，生成G-code并下发到主控制器，主控制器解释命令并控制电机运动，从而完成生物样本冻存管的开盖/关盖及高精度移液操作。系统采用TMC2209驱动器实现256细分微步控制(精度达0.007˚)。实验结果表明，系统对24孔冻存板的操作成功率(当开盖、关盖的个数超过总数的80%即视为此次操作成功) 100%；移液精度误差率小于3.00%；移动误差率不超过7%，当位移大于10 mm时误差率可不超过0.85%。为中小型实验室提供了高性能自动化解决方案。

Abstract: Based on the urgent demand for low-cost, high-precision automated equipment in biomedical laboratories, an automated liquid handling system was designed and developed, which is based on multi-axis pulse timing control using G-code. The system adopts a modular architecture, utilizing the MKS Monster8 V2 as the main controller equipped with customized Marlin firmware. It integrates six 42 stepper motors. The pulse-displacement-velocity relationship was derived, and the pulse frequency for each axis was calculated based on a time reference. In the software, synchronous interpolation for multiple axes—including rotation, lifting, liquid handling, and XYZ movement—is computed. G-code is generated and sent to the main controller, which interprets the commands and controls the motor movements to perform the opening/closing of cryovial lids and high-precision liquid handling operations for biological samples. The system employs TMC2209 drivers to achieve 256 microstep resolution control (accuracy up to 0.007˚). Experimental results demonstrate that the system achieved a 100% success rate in operations on a 24-well cryovial plate, where an operation was considered successful if over 80% of the lids were successfully opened or closed. The pipetting accuracy error was less than 3.00%; the movement error was less than 7%, and could be reduced to less than 0.85% when the displacement exceeded 10 mm. This system provides a high-performance automation solution for small and medium-sized laboratories.