“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.