STEM Coding Max

Model 10: Plotter

I write and paint your idea!

 

Grade
5 - 7
Time required
2 (up to 8) double hours
Difficulty level
Model: medium to hard, Programming: medium to hard
Model type
mobile device, can be positioned and used individually
Download didactic material

MODEL DESCRIPTION / TASK

The pupils (SuS) plan and realize a plotter that can record routes and thus enable the automated creation of line drawings. A two-axis plotter is built for this purpose, which can be moved in the x and y directions using a worm drive. The plotter can safely move to its start or end position by means of a limit switch for each axis. The travel paths are measured using pulse wheels with 4 pulses per revolution, so that the plotter can be positioned with an accuracy of ¼ revolution. 

EVERYDAY USE

The automatic triggering of a process has a strong motivational effect on pupils. The automatic creation of line drawings is quick and easy for everyone to grasp. Two possible additions to the basic task make it possible to
individualization of the topic. The topic could be integrated into pre-vocational orientation with regard to information technology or design professions. Automated printing or drawing (plotting) is used in many areas here. In particular, the sensor-based recording of movements is becoming increasingly important in many areas of production technology, e.g. laser cutting or 3D printing. The two-axis plotter is therefore a very good introduction to automated 3-axis production

Key questions

  • Where can automatic drawing or cutting be used in everyday life? (Communication)
  • What functions does the system need to fulfill? (Collaboration)
  • Under what conditions should the system switch on or off? (critical thinking)
  • What needs to be considered to ensure that the system can be used with different media (paper, film) and that the system functions as robustly and reliably as possible? (creativity)

Subject reference
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Computer sience
Programming basics, time loops, saving variables, comparisons, loops, travel paths
Technology
Stable construction, construction technology, gears, conversion of rotation into linear motion
Physics
Electric motor, change in motion, linear motion
Mathematics
Coordinate system, coordinate geometry, linear functions

Lesson progression

 

Introduction phase

Class discussion (without app)

  • Announce the topic; if necessary, use “3D printer in action” or show the shutter/screen control in the classroom.
  • Ask what this control system is all about, automation vs. manual control
  • Query scenarios in which technical systems that move automatically in a linear fashion are used (roller shutters, yard gate, 3D printer, CNC milling machine, cutting plotter ...)
  • Discuss possible applications of the scenarios collected.
  • Determine the requirements for a two-axis plotter.
  • Discuss the advantages and disadvantages of different types of drive (chain/wheels/worm).
  • Justify the need for a limit switch, a travel or time control and an emergency stop switch.

Assistance if necessary

  • Show sensors, actuators and components from the construction kit, use presentation media if necessary.
Planning phase

Lesson discussion

  • The procedure for building the model and the function to be achieved are worked out together.
  • Sequence steps of the app are specified or discussed

Partner or individual work (with app)

  • Pupils familiarize themselves with the app and download the corresponding task.
  • Pupils recognize useful functions of a plotter.
  • Pupils create a list of requirements for the device.

Optional partner or group work (without app)

  • Pupils optionally sketch the possible two-axis plotter.
  • Pupils discuss their results in the group and decide on a design.
Construction phase

Partner or individual work

  • Pupils use the app to build the plotter. The app guides them through the program in small steps.
Programming phase

Partner or group work

  • The pupils write the program for the two-axis plotter (2 motors / 4 buttons). The app guides them through the program in small steps.
  • Help is provided in the app.
  • The complete program is transferred to the RX controller.
Experimentation and test phase

Partner or group work

  • The plotter is put into operation and tested.
  • The program is started and stopped by pressing the On/Off button on the controller.
  • Possible malfunctions in the function sequence must be found and eliminated.
  • Possible troubleshooting using suggestions in the app.
  • Possible optimization of the hardware (e.g. second linear guide, second limit switch, optimization of the pin holder) and the programming.
Final phase

Optional: Presentation and allocation of the differentiations

  • The possibility of differentiation for fast pupils is offered in the app.
  • The teacher addresses eligible pupils. The further procedure is implemented using the app.

Discussion in plenary

  • Debriefing of the project in class.
  • Clarification of future possible applications in everyday life (transfer of the topic to everyday life), e.g. plotter, printer, CNC milling machine, automated production.

 

Information and notes

 

Methodical and didactic tips

 

Differentiation options

Faster pupils can be given the task of extending or shortening the playing time.

Motivational aspects

Pupils are familiar with grab machines from various locations in everyday life. Perhaps they have already operated such a gripper machine. Being on the “production side” instead of the “operator side” may fill them with pride.

Additional material

  • If available, pictures of free machines can be presented for the introduction to the topic.
  • If necessary, drawing media (paper, whiteboard or projection screen).

Building instructions

Circuit diagram

Functions of the model and their technical solutions

 

Function of the sensors/actuators

 

Technical solution

 

Executing a movement in the x-direction

 

Control of the x-axis motor

 

 

Executing a movement in the y-direction

 

Control of the y-axis motor

 

 

Stopping the movement in the x-direction

 

Evaluating the signals at the limit switch

 

 

Stopping the movement in the y-direction

 

Evaluating the signals on the limit switch

 

 

Controlling the movement in x-direction

 

Evaluating the signals on the rotation counter/button

 

 

Controlling the movement in y-direction

 

Evaluating the signals on the rotation counter/button

 

 

Start a drawing

 

Input of a signal at the On/Off button of the controller

 

 

End/emergency stop

 

Input of a signal at the On/Off button on the controller

 

Material list
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Sensors

 

 

Function

 

1 On/Off  button on the Controller

 

 

  1. Switching on the plotter
  2. Emergency top of the plotter

 

2 buttons

 

Limit switches x- and y-axis

 

 

2 buttons

 

 

Rotation counter per axis in 90° steps

 

 


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Actuators

 

 

Function

 

 

2 motors

 

 

Motion

 

1 LED

 

Status display Pen holder

 
















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