目的 提高包装机混合式定量的称重精度。方法 针对包装机混合式定量称重系统具有非线性和时滞性的特点，构造三支路结构的双自由度数字控制器（RST控制器），等效为前向预测控制器和无延时控制器，以消除系统扰动和滞后的影响，设计基于RST的包装机定量称重控制系统。运用Simulink工具与传统PID控制器和PID-Smith控制器进行仿真对比。结果 RST控制器相较于PID控制器和PID-Smith控制器超调量小、调节时间短、跟踪能力好、鲁棒性强，能够有效地提高包装机称重控制系统的稳定性和控制精度。结论 RST控制器能够提高包装机混合式定量称重精度，从而提高包装机的包装精度。

The work aims to improve the accuracy of hybrid quantitative weighing for packaging machines. With respect to the hybrid quantitative weighing system for the packaging machines featured by nonlinearity and time delay, the double-freedom-degree digital controller (RST controller) of a three-branch structure was constructed. Equivalent to a forward predictive controller and a no-time-delay controller, the RST controller could eliminate the effects of disturbances and delays on the system. A quantitative weighing control system for packaging machines based on RST was designed. The simulation comparison of traditional PID controller and PID-Smith controller was conducted with Simulink tool. The simulation results showed that, compared with the PID controller and the PID-Smith controller, the RST controller had less overshoot, shorter adjustment time, better tracking ability and stronger robustness. It could effectively improve the stability and control accuracy of the weighing control system for the packaging machines. The RST controller can improve the accuracy of hybrid quantitative weighing for packaging machines, so as to improve the packaging accuracy of the packaging machine.