数字工厂研究室知识库

差示扫描量热仪温度控制具有滞后、非线性等特点,难以得到精确的数学模型.针对这些特点,提出一种前馈-反馈复合多控制器算法.针对滞后特性,采用一种改进的PID(proportional-integral-differential)算法,通过对常规PID算法加入微分积分环节,补偿滞后对控制过程的作用.针对非线性特性,提出建立多个近似线性子控制器的多控制器方法,并通过加入平滑滤波因子解决控制器切换过程中引起的控制量突变的问题.针对反馈控制在起始阶段调节时间长的问题,加入前馈控制器设计前馈-反馈复合控制器.将所提控制算法应用于差示扫描量热仪恒速升温控制过程中,结果表明,所提算法能够减小响应时间,提高控制精度,控制效果明显优于常规控制算法.

The temperature control process of the differential scanning calorimeter has the characteristics of time-delay and nonlinearity and it is intractable to obtain the exact mathematic model. A feedforward-feedback multiple control algorithm is proposed to improve the control performance while considering these instrumentation features. Firstly, regarding the time-delay issue, an improved PID (proportional-integral-differential) algorithm is used for compensating the hysteresis effect on control process by adding differential and integral operators. Secondly, in order to solve the nonlinear problem, a multiple controller method is proposed to establish several approximate linear controllers, and a smoothing filter factor is added to solve the sudden change of the control variable caused by the switching process of the controller. Finally, in order to solve the long adjusting time of feedback controller, feedforward controller is added to design feedforward-feedback compound controller.The proposed control algorithm is then applied to the constant speed heating-up temperature control of differential scanning calorimeter.The experimental results show that the proposed algorithm is able to improve the control precision, reduce response time and the control effect is superior to that of the state-of-the-arts.