MakerBotControlSystem

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* Position (ruler) * Position (ruler)
** Open loop ** Open loop
 +
 +== Variable Definition Table ==
 +
 +=== Global Variables ===
 +
 +{| border="1"
 +! Subsystem
 +! Variable
 +! Units
 +! Description
 +|-
 +|rowspan="1"|Global
 +|T<sub>ra</sub>
 +|Celcius
 +|Room Ambient temperature
 +|}
 +
 +=== Build Platform and Chamber ===
 +
 +{| border="1"
 +! Subsystem
 +! Variable
 +! Units
 +! Description
 +|-
 +|rowspan="3"|Build Platform
 +|V<sub>bp</sub>
 +|Volts
 +|Build Platform, PWM generated voltage through nichrome
 +|-
 +|T<sub>bp</sub>
 +|Celcius
 +|Build Platform temperature, ADC sampled thermistor
 +|-
 +|M<sub>bp</sub>
 +|grams
 +|Build Platform mass, including deposited material over time.
 +|-
 +|rowspan="1"|Build Chamber
 +|T<sub>bc</sub>
 +|Celcius
 +|Build Chamber temperature, ADC sampled thermistor
 +|}
 +
 +=== Extruder ===
 +
 +{| border="1"
 +! Subsystem
 +! Variable
 +! Units
 +! Description
 +|-
 +|rowspan="7"|Extruder
 +|V<sub>em</sub>
 +|Volts
 +|Extruder Motor, geared DC, PWM generated voltage
 +|-
 +|&theta;<sub>we</sub>
 +|Degrees
 +|Rotational Extruder displacement of drive motor shaft.
 +|-
 +|V<sub>eh</sub>
 +|Volts
 +|Extruder Heater, PWM generated voltage through nichrome
 +|-
 +|T<sub>en</sub>
 +|Celcius
 +|Extruder nozzle temperature, ADC sampled thermistor
 +|-
 +|D<sub>if</sub>
 +|mm
 +|Input Filament diameter, entering extruder
 +|-
 +|D<sub>ef</sub>
 +|mm
 +|Exiting Filament diameter, emerging from nozzle
 +|-
 +|D<sub>en</sub>
 +|mm
 +|Exit Nozzle diameter
 +|}
 +
 +=== Motion Control ===
 +
 +{| border="1"
 +! Subsystem
 +! Variable
 +! Units
 +! Description
 +|-
 +|rowspan="3"|X Axis
 +|V<sub>lx</sub>
 +|mm/s
 +|Linear X velocity
 +|-
 +|D<sub>lx</sub>
 +|mm
 +|Linear X position
 +|-
 +|&theta;<sub>wx</sub>
 +|Degrees
 +|Rotational X displacement of drive motor shaft.
 +|-
 +|rowspan="3"|Y Axis
 +|V<sub>ly</sub>
 +|mm/s
 +|Linear Y velocity
 +|-
 +|D<sub>ly</sub>
 +|mm
 +|Linear Y position
 +|-
 +|&theta;<sub>wy</sub>
 +|Degrees
 +|Rotational Y displacement of drive motor shaft.
 +|-
 +|rowspan="3"|Z Axis
 +|V<sub>lz</sub>
 +|mm/s
 +|Linear Z velocity
 +|-
 +|D<sub>lz</sub>
 +|mm
 +|Linear Z position
 +|-
 +|&theta;<sub>wz</sub>
 +|Degrees
 +|Rotational Z displacement of drive motor shaft.
 +|}
= References = = References =
 +
 +== Books ==
 +
 +* Digital Control Systems Design
 +** Authors: Mohammed S. Santina, Allen R. Stubberud, Gene H. Hostetter
 +** ISBN 0-03-076012-7
 +* Modern Control Systems
 +** Authors: Richard C. Dorf, Robert H. Bishop
 +** ISBN 0-201-50174-0
== Online Course Material == == Online Course Material ==
Line 90: Line 228:
==== Mechanical Engineering ==== ==== Mechanical Engineering ====
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-001Fall-2006/CourseHome/index.htm 2.001 Mechanics & Materials I]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-002Spring2004/CourseHome/index.htm 2.002 Mechanics and Materials II]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-003Spring-2005/CourseHome/index.htm 2.003 Modeling Dynamics and Control I]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-003JSpring-2007/CourseHome/index.htm 2.003J / 1.053J Dynamics and Control I]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-004Fall-2007/CourseHome/index.htm 2.004 Systems, Modeling, and Control II]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-12Fall-2005/CourseHome/index.htm 2.12 Introduction to Robotics]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-72Spring-2009/CourseHome/index.htm 2.72 Elements of Mechanical Design]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-067Spring-2004/CourseHome/index.htm 2.067 Advanced Structural Dynamics and Acoustics (13.811)]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-093Computer-Methods-in-DynamicsFall2002/CourseHome/index.htm 2.093 Computer Methods in Dynamics]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-094Spring-2008/CourseHome/index.htm 2.094 Finite Element Analysis of Solids and Fluids]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-158JSpring-2003/CourseHome/index.htm 2.158J / 1.128J / 16.940J Computational Geometry]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-171Fall-2006/CourseHome/index.htm 2.171 Analysis and Design of Digital Control Systems]
 +* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-26Spring2004/CourseHome/index.htm 2.26 Compressible Fluid Dynamics]
* [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-830JSpring-2008/CourseHome/index.htm 2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6303)] * [http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-830JSpring-2008/CourseHome/index.htm 2.830J / 6.780J / ESD.63J Control of Manufacturing Processes (SMA 6303)]
Line 108: Line 259:
* [http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/3-22Spring-2008/CourseHome/index.htm 3.22 Mechanical Behavior of Materials] * [http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/3-22Spring-2008/CourseHome/index.htm 3.22 Mechanical Behavior of Materials]
* [http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/3-225Fall-2007/CourseHome/index.htm 3.225 Electronic and Mechanical Properties of Materials] * [http://ocw.mit.edu/OcwWeb/Materials-Science-and-Engineering/3-225Fall-2007/CourseHome/index.htm 3.225 Electronic and Mechanical Properties of Materials]
 +
 +== Other ==
 +
 +* [http://barzilai.org/math_sym.htm Math Characters in HTML]

Current revision

Contents

MakerBot: Control System Design, Implementation and Characterization

Time to brush off some of that rusty old control system design knowledge I once majored in.

Goals

My goals will be to:

  • Describe the MakerBot thermal, electrical and mechanical system in terms of a state-space model.
  • Model said system using the GNU Octave free open-source software (FOSS) suite of tools.
  • Design test and measurement criteria and data to generate a set of parameter estimation functions to calibrate the control system model.
  • Generate discrete-time state-space octave model.
  • Implement discrete-time algorithm using microcontroller or DSP (as required).

The Model

Controllable Parameters

Extruder

  • Heater On/Off (PWM control code)
  • DC Motor Voltage (PWM control code)
  • Nozzle aperture diameter (fixed)
  • Incoming filament diameter (fixed)

X Axis

  • Stepper Velocity (step rate)

Y Axis

  • Stepper Velocity (step rate)

Z Axis

  • Stepper Velocity (step rate)

Observable Parameters

Extruder

  • Relative Nozzle Temperature (thermistor ADC code)
    • Closed loop
  • Calibrated Nozzle Temperature (thermocouple based digital thermometer)
    • Open loop
  • Incoming filament position (with encoder wheel/sensor)
    • Closed loop
  • Incoming filament travel (callipers)
    • Open loop
  • Outgoing filament diameter (callipers)
    • Open loop
  • Outgoing filament length (callipers)
    • Open loop
  • Outgoing filament mass (scale)
    • Open loop
    • Possibly closed loop with build platform integrated weight cells.

X Axis

  • Endstop activation
    • Closed loop
  • Position (ruler)
    • Open loop

Y Axis

  • Endstop activation
    • Closed loop
  • Position (ruler)
    • Open loop

Z Axis

  • Endstop activation
    • Closed loop
  • Position (ruler)
    • Open loop

Variable Definition Table

Global Variables

Subsystem Variable Units Description
Global Tra Celcius Room Ambient temperature

Build Platform and Chamber

Subsystem Variable Units Description
Build Platform Vbp Volts Build Platform, PWM generated voltage through nichrome
Tbp Celcius Build Platform temperature, ADC sampled thermistor
Mbp grams Build Platform mass, including deposited material over time.
Build Chamber Tbc Celcius Build Chamber temperature, ADC sampled thermistor

Extruder

Subsystem Variable Units Description
Extruder Vem Volts Extruder Motor, geared DC, PWM generated voltage
θwe Degrees Rotational Extruder displacement of drive motor shaft.
Veh Volts Extruder Heater, PWM generated voltage through nichrome
Ten Celcius Extruder nozzle temperature, ADC sampled thermistor
Dif mm Input Filament diameter, entering extruder
Def mm Exiting Filament diameter, emerging from nozzle
Den mm Exit Nozzle diameter

Motion Control

Subsystem Variable Units Description
X Axis Vlx mm/s Linear X velocity
Dlx mm Linear X position
θwx Degrees Rotational X displacement of drive motor shaft.
Y Axis Vly mm/s Linear Y velocity
Dly mm Linear Y position
θwy Degrees Rotational Y displacement of drive motor shaft.
Z Axis Vlz mm/s Linear Z velocity
Dlz mm Linear Z position
θwz Degrees Rotational Z displacement of drive motor shaft.

References

Books

  • Digital Control Systems Design
  • Modern Control Systems

Online Course Material

MIT OpenCourseWare

Electrical Engineering and Computer Science

Mechanical Engineering

Materials Science and Engineering

Other

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