View source for Spike Prime - Self-correcting Codes

<small>(''[[Spike up Prime Interest in Mathematics|back to list of projects]]'')</small>

== 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:

[[Image:self_correcting_model.png|model of machine|300px]]

Pictures:

[[Image:self_correct2.jpg|robot that can write and read message and correct an error automatically|600px]]

[[Image:self_correct1.jpg|robot that can write and read message and correct an error automatically|720px]]

[[Image:self_correct3.jpg|robot that can write and read message and correct an error automatically|480px]]
[[Image:self_correct4.jpg|robot that can write and read message and correct an error automatically|400px]]

Building instructions:

* [[Spike Prime - Self-correcting Codes - Building Instructions|Self-correcting messages reading and writing robot (PNG)]]

Download building instructions: 

* [[Media:self_correcting.pdf| whole system (pdf)]]

Download stud.io model:

* [[Media:self_correcting.io|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:

[[Image:spike_self_correct_calibandtest_prg.png|program]]

Writing self-correcting code:

[[Image:spike_self_correct_writehamming_prg.png|program]]

Reading self-correcting code:

[[Image:spike_self_correct_readhamming_prg.png|program]]

Download: 
* [[Media:calib_and_test.llsp|calib_and_test.llsp]] 
* [[Media:write_hamming.llsp|write_hamming.llsp]] 
* [[Media:read_hamming.llsp|read_hamming.llsp]] 

...description...

== Measure, analyze, think ==

<youtube width="404" height="718">yM-DBpv4nH0</youtube>

<youtube>6gPE1AafnFg</youtube>

* 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: [http://robotika.sk/spike/spike_math_7_selfcorrect.zip Self-correcting Codes - all media files]
* 3D printed biscuit replacement: [[Media:biscuit-replacement.stl|biscuit-replacement.stl]]


== 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 [https://bricklink.com BrickLink]'''||'''part name'''||'''comment''' 
|-
|2||	[https://www.bricklink.com/v2/catalog/catalogitem.page?P=15458 15458]||	Technic, Panel Plate 3 x 11 x 1|| 2 are in Spike Prime set
|-
|3||	[https://www.bricklink.com/v2/catalog/catalogitem.page?P=32316 32316]||	Technic, Liftarm Thick 1 x 5||    4 are in Spike Prime set
|-
|4||	[https://www.bricklink.com/v2/catalog/catalogitem.page?P=39793 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||	[https://www.bricklink.com/v2/catalog/catalogitem.page?P=39793 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||	[https://www.bricklink.com/v2/catalog/catalogitem.page?P=64782 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 :-) If you do not have any, send me an e-mail and I will send them to you.
|}

__notoc__