Spike Prime - Self-correcting Codes

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Let's begin

Note: this model requires 1 extra light sensor, and additional extra plastic parts - see bottom of page

Self correcting codes...

Build

Model:

Pictures:

Building instructions:

• Self-correcting messages reading and writing robot (PNG)

Download building instructions:

• whole system (pdf)

Download stud.io model:

• machine (stud.io)

...description...

Connections:

• left motor - E
• right motor - F
• large motor - B
• calibration light sensor - D
• reading light sensor - C

Programs

Calibration and testiing:

Writing self-correcting code:

Reading self-correcting code:

Download:

• calib_and_test.llsp
• write_hamming.llsp
• read_hamming.llsp

...description...

Measure, analyze, think

• Make your own recording

• Perform experiments with your model and discuss in your group what has happened.

Explore and modify

• Think about how a message can be written so that even after flipping any little bit of it, the message could still be safely read without any disturbance.
• Three methods for students to discover:
  • write every bit 3 times (message length = 3 x L)
  • write every bit two times and add one extra bit - parity of ones in the message (message length = 2 x L + 1)
  • write current parity after every single bit (message length = 2 x L)
  • invent your own method, try to use as little bits as possible

Present

• How would you encode the message using tokens of only one color?
• How could a distance traveled between tokens placed be also used for encoding the message?
• How would the situation change, if one bit could be flipped in every 10 bits that we send instead of in the whole message?
• Prepare a short presentation for other groups. Tell others about your experiments with finding circle centers.

Additional resources

• Download: Self-correcting Codes - all media files

Missing parts

This model cannot be built using one Spike Prime set, unfortunately. It requires an extra light sensor and a couple of additional plastic parts:

extra pieces needed	part number, see BrickLink	part name	comment
2	15458	Technic, Panel Plate 3 x 11 x 1	2 are in Spike Prime set
3	32316	Technic, Liftarm Thick 1 x 5	4 are in Spike Prime set
4	39793	Technic, Pin Connector Block, Liftarm 1 x 3 x 3, black	black biscuits, 4 are in Spike Prime Set - can be replaced by 3D printed tokens
2	39793	Technic, Pin Connector Block, Liftarm 1 x 3 x 3, purple	purple biscuits, 6 are in Spike Prime Set - can be replaced by 3D printed tokens
2	64782	Technic, Panel Plate 5 x 11 x 1	this is the most problematic part - each one can be replaced by two 15458, but it is a notoriously used part in FLL and it is contained in 90 LEGO sets, if you do not have these, you do not have LEGO :-)