http://academy.cba.mit.edu/classes/machine_design/index.html

Group assignment

• actuate and automate your machine

• document the group project and your individual contribution

Modulbaseret design men ikke modulbaseret konstruktion.

Error budget for machines:

http://web.mit.edu/2.75/fundamentals/FUNdaMENTALs Book pdf/Precision Machine Design Error Budget.pdf

The structural loop:

• Static error
• Dynamic error
• Maschine Design

A stiff machine reduces error

Make it as small and stiff as possible

Tjek maskines specifikationer:

Vores maskine:

Kør frem og til bage

Control variants:

Feed forward og feed back - requires sensors.

Stepmotoren mister et step, hvis kraften overstiger Torque Force - derfor skal motoren bruges konservativt. There is no feedback and it is thous a open loop system.

En feed back motor, har en roterende encoder indbygget i motoren - så i stedet for at sende et antal skridt, bevæger stepmotoren til en position.

Our design can be based on sensors - and thus creating a closed loop.

Not just send data, data should come back.

Controlling the machine!

Difference between PRSstandard96 96x48x8in:

Bang Bang:

Slam it on - then slam it of, when it is at desired position - might overshoot desired position.

PID:

Proportional I D. Meassure the difference between where you are and where you want to be. If the error is large the output should be large.This adds stress at the start of movement because

Differentiale: The derivitive term: The rate of change. Begrænser

Integrale: Holder styr på bevægelsens basislinjen

PID is the workforce of control, but it is still not good enough.

Model Predictive Control

Der er behov for accellerations- og decellerationsprofiler,

Kræver kendskab til hvor man er og hvor man skal hen.

Det betyder enten en matematisk model eller nødvendige sensorer, så

Machine Control - how you talk to the motor control:

G-code: En udbredt standard but with it's limitations.

Open SBP (ShopBot)

RML

To interpret the code - need for an interpretor

Go from G-code to the steps

Needs to describe the machine - is the machine square, rotary etc.

Transition from machine control to motion control

Any changes to the machine, should be changed in the interpretor. -Makes it unable to make modular machines.

No motion happens faster than a millisecond. - but our microprocessors can do calculations 10.000 times faster.

Network Connected Axis makes it possible to leave out the intepretor.

The computer sends out packages which each microprocesser converts to motion in it's own axis.

Each axis has to be in sync, by either:

• Handshake
• Broadcast: Tell what, tell to get ready, tell when to start
• Timestamp: Tell what to do in the future
• Backpressure:

Pololu - https://www.pololu.com/

Standard board for controlling machines

Stepper Controller

Ramps - http://reprap.org/wiki/RAMPS

A Pololu shield

Shops:

Maskindele: http://openbuildspartstore.com/

Robotdele: https://www.robotshop.com/

Motorer: http://www.orientalmotor.com/

Configuring and compilation:

https://github.com/jcrocholl/Marlin

• Install the arduino software IDE/toolset v23 (Some configurations also work with 1.x.x) http://www.arduino.cc/en/Main/Software
• Download the Marlin firmware https://github.com/ErikZalm/Marlin/tree/Marlin\_v1 Use the "Download Zip" button on the right.
• For gen6/gen7 and sanguinololu the Sanguino directory in the Marlin dir needs to be copied to the arduino environment. copy ArduinoAddons\Arduino_x.x.x\sanguino \hardware\Sanguino
• Start the arduino IDE. Select Tools -> Board -> Arduino Mega 2560 or your microcontroller Select the correct serial port in Tools ->Serial Port Open Marlin.pde
• Click the Verify/Compile button
• Click the Upload button If all goes well the firmware is uploading

Bed Auto Leveling

https://github.com/jcrocholl/Marlin\#instructions-for-configuring-bed-auto-leveling

Servo or Sled Option