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Corrado Govea’s Status Report for April 6th

This week’s accomplishments

  • Finished debugging the LV circuit.
    • Identified issue with LDO voltage regulator not being able to handle the heat generated (Max 150 deg C)
      • Currently .2A * 18V * ~50degC = 180 deg C
    • Solution: We switched to a new pump, which is rated for 5V and 2A. Coincidentally, the power strip we got has a usb port rated precisely for 5V 2A, so we can power the pump directly from there. I need to get a new mosfet that is rated for this current to regulate the voltage drop across the pump.
  • Continued debugging HV AC circuit.
    • Currently only able to turn on/off — can’t regulate voltage at the output.
    • Changed current limiting resistor to match optocoupler’s specification, but this still didn’t solve the issue.
    • Was able to change the resistance across the output of the optocoupler by changing the voltage at the input, but the current delivered to the kettle is the same.
  • Characterized new pump.
    • Conducted test to characterize voltage across pump vs flow rate. The flow rate is a bit higher than we need, so we will design a flow restrictor to bring down to our desired rate. Pump seems suitable for our needs.

Next Week’s Deliverables

  • Order new components (Monday) to match circuit design changes, and decide if it will be necessary to order a new PCB, or if we can repurpose the ones we received.
    • If not, order new PCB by Wed at the latest.
  • Continue to debug HV side to determine what is preventing from doing voltage regulation at the triac.

Extra: System Verification

  • I plan to verify the pump controller circuit + code by running this test:
    • After the entire system is installed, I will place a cup on the machine with a scale we have been using that has a flow meter in g/s. This way, I can verify that the set flow rate and actual flow rate are within the defined margins.
  • To verify the heating element:
    • our max expected heating time will be 3:30min, so we will run 5, 4-min trials where we set a desired temperature and monitor the water temperature to make sure it is within 5degF of the set temp. This will be tested at the outlet to account for heat loss through the pipes.
    • Additionally, I will add a multimeter to the circuit to ensure that we are delivering current to the kettle as expected.

Status Report: On Schedule

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Elijah Knupp’s status report for April 6th

This week’s accomplishments

  • Attended mandatory labs
    • Demonstrated my portion of the project to Prof. Fedder and the TAs, received positive feedback
  • Added a manual taring feature the user can trigger at any time to zero the scale
  • Completed the Arduino’s script for the temperature probe, scale, heater, and PID loop
    • sends serial data from the temperature probe and scale
    • sends a confirmation signal back to the rpi that the change it requested from the PID loop was implemented
    • receives serial input
      • user can send a signal to manually tare the scale
      • receives signals from the rpi-implemented PID loop and turns the water heater on and off wrt to the signal’s value
  • Began testing the PID loop to control the heating element
    • Very close to being fully implemented
      • currently, the loop overshoots the target temperature by around 2-3 degrees Fahrenheit

Next weeks plan

  • Implement the pump into the project.
    • will need to ensure the pump’s flow rate are accurate per the user’s request
      • see testing plan below
  • Finish testing and verifying the PID loop for the heating element
    • see testing plan below
  • begin fabricating all of the different components on to the 3-D printer’s frame
    • will need to 3-D print a mount for the water pump. Will be placed on the very top of the frame.

Status Report: On schedule

 

Verification and Validation

  • Verification:
    • Heating element: As per the design project report, we aim to deliver water within +-5 degrees Fahrenheit of what the user specifies. Mentioned above, we are currently overshooting the temperature by only a couple of degrees. However, this may be necessary due to thermal loss whilst the water travels through the lines, as this temperature reading was taken inside the water heater.
      • TEST
        • Need to test the FULL range of temperatures the user can request (from around 180 – 212 degrees Fahrenheit)
          • Every 4 degrees (180, 184, … 212), will ensure that the temperature of the water hits the coffee grounds at +-5 degrees from the users request (although we will shoot for +-3 degrees)
    • Scale
      • Testing will be simple. The user will be using the integrated scale to check the amount of coffee grounds they have placed into the filter
        • TEST
          • Need to test the full range of weights of coffee grounds the user may use (around 10 – 40 grams of coffee grounds)
            • Every 5 grams, use a known weight to ensure the weight readings are accurate
  • Validation
    • The water system needs to be safe and intuitive for the user. Whilst the software side is being handled by Rio, I will need to make sure that user can easily and SAFELY handle the water system. I will need to ensure that there are no exposed wires or electronics that could be exposed and damaged if some water is spilled around our machine.
      • As of now, the user will need to unscrew the cap of the water heater (which is a converted electric kettle), which will have the temperature probe and tubing attached to this.
        • TEST:
          • I will ask several individuals to screw and unscrew the lid to ensure ease of use and durability of system.
      • Cable management is a major component of this as well. I will need to make sure that no wires could jar loose or come exposed.

 

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Rio Pacheco’s status report for April 6th

This week’s accomplishments

  • Continued work on Django app(6+hrs)
    • https://github.com/Quarks-1/pour-over-and-over
    • Integrate thermal PID algo
    • working live data display on webapp
    • Gcode conversion baseline finished
  • Meet in Techspark on Saturday (today) to work on tuning the thermal PID algorithm  (4hrs)
  • Attended mandatory lab (4hrs)

Next weeks plan

  • Further fine-tune PID algo to get better temp stability
  • Design pump and/or water heater mount
  • Finish code to do pouring and water heating sequence together

Status Report: On schedule

Verification

  • User testing via the UI will be used to test the webapp functionality
  • temperature measurement with an external thermometer will be used to verify temperature readings of integrated thermometer
  • Pour patterns will be drawn on a whiteboard with a market taped to gantry to ensure that pour patterns are consistent and match the dimensions of V60 pour cone