“say when” sweet tea sweetness control
TRANSCRIPT
“Say When” Sweet Tea
Sweetness Control
Group 19:Samantha ButlerNoah Van Ryn
Michael DePietro
Objectives-To design and build a system that controls the sweetness,through sugar
concentration, of sweet tea
Block Diagram
Hardware
Hardware (Sensors)-Load Cell
-Flow Meter (removed)
Hardware con’t (Actuators)-Pump
-Stepper Motor (Auger System)
Hardware concl (Controller)Albert II
The Pump Calibration/Step Changes
Stepper Motor Calibration/Step Test
Time Target = 0.1 to 0.03
𝝉 = 82.504s
Load Cell Calibrations/Step Tests
Simulation vs Real Process
Who will emerge
victorious?
Process Model
-Simulation VI
Final Project VI
Model Compared to System (Gp)Simulation Physical Change in Manipulated Variable
Simulation of Process compared to Real SystemSimulation Tuned System
Simulation of Process compared to Real System con’t (Step Test)Simulation
Tuned System
Tuning Strategy
Tuning our System Proportional Control First Attempt
Rise Time = 60s
Offset difference = 25 (g/L)
Control Effort saturates at at 40s
Tuning Our System Proportional Control Second Attempt
Rise Time = 68s
Offset Differences = 11 g/LControl Effort does not show any saturation
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
Tuning Our System PI Control First Attempt
Rise Time - 37s
Offset difference - 56 g/LControl effort is stable at 0.045 until 8s and
then saturates at 13s and auger stops
working.
Tuning Our System PI Control Second Attempt
Rise time - 83s
Overshoot - 1.16Control effort heads toward saturation at
7s but works its way back up around 80s
Tuning Our System PI Control Third Attempt
Rise Time - 183s
System stayed at setpoint for 30sControl Effort does not saturate and
remains stable
Setpoint Change - Raising SetpointTime to reach new setpoint:
120 s
Setpoint Change - Lowering SetpointTime to reach setpoint - 100 s
Disturbance - Load CellJump in Concentration - 69 g/L to 147 g/L
Time to Return to Setpoint - 210 s
Final Thoughts
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
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
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
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.