1. “Say When” Sweet
Tea
Sweetness Control
Group 19:
Samantha Butler
Noah Van Ryn
Michael DePietro

2. Objectives
-To design and build a system that controls the sweetness,through sugar
concentration, of sweet tea
Block Diagram

3. Hardware

4. Hardware (Sensors)
-Load Cell
-Flow Meter (removed)

5. Hardware con’t (Actuators)
-Pump
-Stepper Motor (Auger System)

6. Hardware concl (Controller)
Albert II

7. The Pump Calibration/Step Changes

8. Stepper Motor Calibration/Step Test
Time Target = 0.1 to 0.03
𝝉 = 82.504s

9. Load Cell Calibrations/Step Tests

10. Simulation vs
Real Process
Who will emerge
victorious?

11. Process Model
-Simulation VI

12. Final Project VI

13. Model Compared to System (Gp)
Simulation Physical Change in Manipulated Variable

14. Simulation of Process compared to Real
System
Simulation Tuned System

15. Simulation of Process compared to Real
System con’t (Step Test)
Simulation
Tuned System

16. Tuning Strategy

17. Tuning our System Proportional Control First Attempt
Rise Time = 60s
Offset difference = 25 (g/L)
Control Effort saturates at at 40s

18. Tuning Our System Proportional Control Second
Attempt
Rise Time = 68s
Offset Differences = 11 g/L
Control Effort does not show any saturation

19. Tuning Our System Proportional Control Third
Attempt
Rise Time - N/A
Offset Difference - 75 g/L Control Effort immediately saturates and
the auger did not move

20. Tuning Our System PI Control First Attempt
Rise Time - 37s
Offset difference - 56 g/L
Control effort is stable at 0.045 until 8s and
then saturates at 13s and auger stops
working.

21. Tuning Our System PI Control Second Attempt
Rise time - 83s
Overshoot - 1.16
Control effort heads toward saturation at
7s but works its way back up around 80s

22. Tuning Our System PI Control Third Attempt
Rise Time - 183s
System stayed at setpoint for 30s
Control Effort does not saturate and
remains stable

23. Setpoint Change - Raising Setpoint
Time to reach new setpoint:
120 s

24. Setpoint Change - Lowering Setpoint
Time to reach setpoint - 100 s

25. Disturbance - Load Cell
Jump in Concentration - 69 g/L to 147 g/L
Time to Return to Setpoint - 210 s

26. Final Thoughts

27. Challenges
1. Not able to directly measure sugar concentration
2. Building around the load cell
a. Placement of hot plate
b. How to build a platform on load cell
c. Determining our batch size
3. Flow meter
4. Pump start up
5. The ALBERT II
6. How to dissolve sugar
7. PID tuning

28. VI Improvements
-Add a sequence structure to the VI that will turn off the pump and load cell once
the PID system is turned off
-Find a way to tare the load cell at the beginning of each batch
-Program the system so that the auger and pump turn on simultaneously instead of
turning them both in separately
- Find a way to incorporate the flow meter
- Figure out why we couldn’t start with an integral time right away

29. Hardware Improvements
-Develop a way to more permanently attach the auger screw to the stepper motor
-Develop a method that allows for aggressive agitation of the brewing vessel in
order to increase the rate at which sugar dissolves into the unsweetened tea
-Stronger pump for faster addition of unsweetened tea
-Stop sugar from escaping out the back of the system and prevent it from getting
into the auger shaft

30. Conclusion
-We feel that our project performed in a satisfactory manner.
-We were able to complete all of our goals, namely we were able to control the
sugar concentration of a batch of sweet tea.