How is Mercator Origins a piece of Assistive Tech?

With the end date for the challenge round for the Assistive Tech category of the Hackaday 2023 prize fast approaching (30 May 3pm BST) I wanted to write a log on how the audio module is going.

With the added Audio Module, Mercator Origins will be able to provide guided assistance through sounds, tones, vibrations and spoken instructions. This is in addition to the usual visual guidance provided today. 

I was speaking to a doctor who specialises in dive medicine and who also is involved with a charity who teaches and enables disabled people to scuba dive. He told me a story about the bravest person he knows, who has impaired vision. They found the feeling of being weightless (and neutrally buoyant) in the water was one of the most empowering and moving experiences of their life as they could be independent. I would like to think that scuba diving can provoke a feeling of autonomy and empowerment for those who have difficulties with movement or who are challenged by the clutter and busyness of our everyday lives. Using only the breath to control one's attitude (ie angle) and position in the water column is something that I love as a sighted person, so if this can be experienced similarly for people who wouldn't think that this sort of thing is accessible then that would be awesome.

I am told that a person who has an impaired sense, for example sight or hearing, is quite likely to have a more highly tuned ability (compared to the unimpaired person)  to experience their other, unimpaired, senses. It is for this reason why I believe that empowering impaired-sight and blind people to enjoy the underwater world, one of weightlessness and freedom in 3D space/water, is something which might provide a wonderful experience that is outside their usual day-to-day living. To give hope and joy to a person who has challenges that I cannot begin to fully appreciate due to my sightedness and life long exposure to the world through the wonder of vision is something which I have a tremendous drive for and why I have devoted so much time and effort throughout 2023 to this project.

Attuned Senses, Inclusion and the Desire to Expand a Person's World Experience

One or two people have questioned why a sight impaired person would like to visit underwater features in a dive lake or in the sea when they can't see them. I think this is one of the challenges we all have when making the world inclusive for all. It can be hard to imagine or put ourselves in the shoes of those who have a vastly different life experience to ourselves or to the usual day-to-day experience of the majority. 

I would love a person with impaired sight to be able to visualise in their mind's eye the feature that they are visiting by reaching out and touching the object, feeling the contours and experiencing the textures and embodiment of the structure. In the dive lake at Wraysbury it is perfectly safe to touch all the objects (with gloves, there are some rough and rusty bits!)  and there are no corals or other delicate organisms which can be damaged by a person reaching out and touching their surface. There are plenty of fresh water mussels which are very resilient to us humans and also freshwater American Crayfish which crawl about the lake bed minding their own business. There are fish too, but they are not going to roll over to have their tummy tickled - unlike some Grouper fish I have seen in Turkey,

I would like Mercator Origins to guide the person around the lake using sounds, feature by feature, whilst they are still accompanied by their dive buddy / instructor who is always there to provide a helping hand and for good dive practice safety. The aim is to provide a unique experience in a safe environment to provide an empowering feeling of autonomy to the person using the Mercator Origins guidance system.

So there we have it, an audio-enabled Mercator Origins is a piece of tech that can help people with impaired vision have magical experiences under water, whilst experiencing autonomy and the empowerment of not needing to hold someone's hand.

The challenge of adding audio directions to Mercator Origins

Firstly, the challenge with Silky is that I need a separate enclosure to house the speaker system because there is no physical space remaining in the console enclosure. Silky will need its own power supply (an on-board lithium rechargeable battery) because I want 3 to 4 Watts of power available to drive the audio transducers. At 3.3V this equates to 1 Amp, though Mako/Lemon/Tiger are running on a 5V source in the float. Due to line losses where the resistance of the cable from float to console drops the 5V source to 4.2 to 4.5V at 11m cable length, I can't use this power supply for audio as I will be taking 1 Amp at 3.3V so I don't want it to run on the power system for the Mako/Lemon/Tiger microcontrollers.

Using a cable to link the console module to the audio module will be cumbersome and also risky because there will be two more ways for water to potentially enter the system.

This is how I am overcoming these challenges:

1. ESPNow is a proprietary WiFi protocol provided by the ESP32 family of ICs which is very good for sending short messages without the radio handshaking needed to maintain a continuous wireless connection. I will use ESPNow to communicate, through water, between the Mako microcontroller in the console and the Slinky microcontroller in the audio module.

I made a YouTube video documenting my scientific experiment to find out whether this would be feasible or not - because WiFi frequencies of 2.4GHz are absorbed by water and can only travel short distances... but how short? 15cm in turns out, regardless of fresh or salt water - I need the signals to travers 7 to 8 cm of water from one side of the cable spool to the other so it should work!

Youtube Video: Audio Navigation Science Experiment - can we use WiFi to communicate underwater?

Have a watch of my video to see how I discovered that WiFI can be used to make the navigation console and audio module communicate with eachother. As for all my videos, this hasn't been rehearsed and it was done in one take. I like to show my authentic me, uncut! I'm new to youtube so don't have the editing thing sorted out yet, but I'm happy with the results!

First test was fresh water (0% salinity) and I'm then finding out whether making the water as salty as the English Channel (3.5% salinity), and then as salty as the Red Sea (4.0% salinity) makes any difference.

And this is how we tell that WiFi is go, go, go! Two M5 Stick C Plus microcontrollers using the ESP32 magical superpower of ESPNow WiFi for embedded devices... the video shows individual bytes (for that is all I need to command left, right, ahead) being transferred in real-time through the water. The WiFi signals cannot travel through the plastic bucket downwards due to the lead blocks underneath them. They can only travel horizontally :-).

This is how the Audio Module electronics looked before coding up the software:

Youtube Short Video - Bring on Audio Directions!

And the rocking and rolling result!

And then the lament! The Beetle ESP32-C3 that is Slinky is poorly. She is sick and has stopped communicating using the serial SPI protocol to the SD Card. A total disassembly showed me that it is most likely the Beetle at fault, let's not cry over spilt electrons... I have a new Beetle arriving tomorrow along with a couple of other spares so I will try again! Never give up ;-)