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Team Churro: Sharon Grimshaw, Maggie Su, Louis
Yi, and Morgan Zheng
Project Goals
 Safe
 Heat: no burns
 Moving components: no pinching
 Easy
 Loading: one container, easily removed, to fill
 Cooking: machine removes when done
 User choice
 Length or number of churros
 Shape of churro
The Website
Initial Idea
Mechanical Subsystem
 Extruder
 Cutter/Shaper
 Stirrer
 Lifter
 Shaker
Mechanical Subsystem – Lifter
Initial Idea:
Need to lift an assembly consisting of a stirring mechanism with a platform
and a mesh grid.
Revised Idea:
Only lifting mesh grid, but need to constrain vertical motion
Pulley System
Rack and Pinion
 Vertical lifting
 Vertical lifting
 Can lift more weight
 Too much load on gear/motor,
 Can still use 1 motor to
control movements of 2 sets
of pulleys
assuming initial idea of lifting
stirrer and mesh grid assembly.
 Use 1 motor to lift all
 Gear & racks may be expensive
Mechanical Subsystem - Extruder
 How to keep the threaded rod vertical?
 Guide hole
 Fixed to the motor
 Will we have enough torque?
 Stepper motor instead of servo
 Gears
Mechanical Subsystem - Structure
Stability through weight
Stability through attachment
 Make supports heavier so that
 Attach supports (L brackets)
pieces don’t move
 Overall smaller system
 Difficult to move around
(multiple heavy pieces)
to base and frames so they do
not move
 Easier to transport because
only one piece
 Easier to set up because
distance between pieces is
predefined
 Large, bulky system
Electrical Subsystem - Overview
 To be powered on 12 volts
 2 stepper motors
 3 servo
 Temperature gauge
 Thermocouple
 Instrumentation amplifier
 Character LCD display
Electrical Subsystem – Stepper
Control
Basic H-bridge driver:
Requires four input pins to control each motor
Revised two-pin control:
Uses transistors to set polarity across coils – two input pins per stepper
Software Component
 Motor control – Arduino Stepper/Servo Libraries
 Stirrer/Shaker can run on a loop
 Extruder, cutter, and lifter relies on user input
 GUI
 Python


Serial communication is relatively easy to deal with
Lots of GUI libraries to choose from – some of which are painful to
deal with
 Processing
 Theoretically very good for Arduino GUIs
 Requires generic firmware that communicates with a Processing
Library – may interfere with the use of other Arduino libraries.
Where we’re going…
Questions? Comments? Concerns?