The Design And Realization On The Automatic Mixing System For Oral Liquid

Most domestic oral liquid devices are imported from abroad with high prices and long profitable time. So we design a kind of Automatic Liquid system with low price.First, design the automatic liquid mix system hardware:main control board、 drive board、human-machine interface. Control board complete the signal conditioning、sensor-driving、signal acquisition and processed, to replace the costly PLC and complete data acquisition and control; SSR solid state relay driver board are used to replace the relay switch in order to prolong life and improve quality control. Human-computer interface design employs programmable operation device(POD) to replace the industry computer in order to reduce product cost and improve system reliability.Second, have a research on the mix algorithm. By building the mathematical model and simulation, the thesis shows the liquid system have obvious error based on the traditional PI and bang-bang controller. After the Smith prediction control is involved in, simulation shows that PI control and bang-bang control based on Smith prediction control has overcome the disadvantages of usual PI control, and the steady state error is nearly to zero, meaning better control effects. But the simulation reveals the Smith control has much error when the Smith model is not accurate. Considering this, the paper put forward to a improved Smith algorithm by modifying the parameter on line and the simulation shows it has overcome the drawback of the former; then applies it to the software program.At last, practice has proved that the system fully meets the design requirements and has faster response speed, good control precision, high reliability, strong anti-interference, friendly interface and easy to operate.