How to use ReNav
A complete guide for caregivers and families — from first setup to your first conversation.
Tip: the patient needs a laptop, desktop or large tablet to use the app. This guide works on any device.
On this page
What is ReNav? Getting Started Choosing a Mode Head Mode & Calibration Blink-Only Mode Morse Mode Using the App Calling for Help Button Layout App Menu Tips for Best Results AI Personalisation Dashboard Troubleshooting Patient Face Check Privacy & Security PlansGetting Started
Setting up ReNav takes less than 5 minutes.
Create an Account
Go to the signup page, enter the patient's name, choose a username and password, then click Create Account.
Open the App on a Large Screen
The eye-tracking requires a laptop, desktop, or large tablet in landscape mode. The app will show a warning if the screen is too small.
Allow Camera & Microphone
When the app first loads, your browser will ask for camera and microphone permission. Click Allow for both — this is required for the app to work.
Complete the Calibration
A 5-point calibration runs automatically on first launch. Follow the on-screen dots to calibrate head tracking for the patient. See the Calibration section below for details.
Every account gets five AI questions a day at no cost, and Morse mode is unlimited on every plan — the patient's own words are never rationed. If you need unlimited AI questions, see the plans.
Choosing a Mode
Paralysis is not one condition, so ReNav offers three ways to answer. The first time you open the app it asks which one to use, and you can change it at any time from the ☰ menu → Mode without losing history or settings.
Head movement — if the patient can turn their head
Turning the head towards an answer highlights it; one blink chooses it. The fastest option, and the one to try first if there is any neck movement at all.
Blink only — if they cannot move their neck
The four answers are scanned rather than pointed at. A short blink steps to the next one, a long blink chooses it. Nothing but the eyelids is needed.
Morse — when the answer isn't one of the four
The same two blinks, but the patient spells out whatever they want to say. Much slower, and worth it when the four options don't cover what they mean.
Start with blink only. It works for everyone regardless of neck movement, and if the patient turns out to have usable head control you can switch to head mode in one tap and gain the speed.
The first time you use a mode, ReNav walks you through it in about 30 seconds. You can replay the tour for the current mode any time from the ☰ menu → Tour.
Head Mode & Calibration
In head mode the screen is split into four answer zones. The patient turns their head towards the answer they want, which highlights it, then blinks once to choose it. This is the fastest of the three modes.
Calibration teaches the app how the patient's head naturally moves, so the four zones map accurately to their range of motion. It takes about a minute and only needs redoing when the patient or the device is repositioned.
Press Start when the patient is ready
Calibration opens on a summary screen with a camera preview so you can check the patient's face is framed and lit. Nothing is measured until you press Start Calibration — take as long as you need to get them comfortable.
A dot appears, with a countdown
A glowing dot appears in 5 positions: centre, then each corner. A 3·2·1 countdown gives the patient time to turn towards it. Nothing is recorded during the countdown — only once it reaches zero.
Hold still while the bar fills
The patient gently moves their head — not just their eyes — so their nose points at the dot, and holds while a bar fills. If the app records too little movement it will say so and ask you to try again, turning the head further.
Mirror is auto-detected
The app works out on its own whether the camera feed is mirrored — no manual setting needed. Calibration is saved in the browser and persists between sessions.
At the start of every new session ReNav shows a banner suggesting you recalibrate — head position drifts between sessions, and a minute spent here saves a lot of frustration. You can also redo it any time from the ☰ menu → Calibrate, or skip it and use rough default tracking.
Calibrate under the same lighting conditions you plan to use the app. Changing from bright to dim lighting can reduce tracking accuracy and may require recalibration.
Blink-Only Mode
For patients with no usable neck movement — including locked-in patients. There is no gaze calibration in this mode, because the head is never used. Instead the four answers are scanned: one is always highlighted with a white border, and the patient moves that highlight with their eyelids.
Short blink — move to the next answer
A quick, normal blink steps the highlight to the next answer. After the fourth it moves to None of these in the middle, then back to the first. Cycling is silent so it stays quick; only the answer finally chosen is spoken aloud.
Long blink — choose the highlighted answer
Closing the eyes and holding chooses whatever is highlighted. A white bar fills along the bottom of that answer as the patient holds — when it completes, the answer is selected and read aloud.
The blink check
Before first use, ReNav runs a short check: a few seconds of open eyes, then one short blink, then one long blink. The long blink is held until the app says "now open your eyes" — the step completes on the eyes reopening, and it is spoken because the patient cannot read the screen with their eyes shut. It confirms detection is working before the patient depends on it, and it is suggested again at the start of each session because lighting changes.
How long a "long blink" must be held is adjustable from the ☰ menu → Blink speed: Fast, Normal (the default) or Relaxed. If the patient finds holding tiring, choose Fast. If short blinks are being mistaken for long ones, choose Relaxed.
If blinking is tiring, turn on Auto-scan from the menu. The highlight then advances by itself every few seconds and the patient only needs a single long blink to choose — one blink per answer instead of up to four. It never advances while their eyes are closed.
There is a deliberate gap between "short" and "long". A blink that lands in between is ignored rather than guessed at. This costs one extra blink occasionally, and it is what stops the app speaking an answer the patient never chose.
Morse Mode
Sometimes the right answer isn't one of the four. In Morse mode the patient spells their own reply — using the same two blinks as blink mode, so the skill carries straight over. No AI options are generated in this mode.
Short blink is a dot
A quick, normal blink adds a dot to the letter being spelled.
Long blink is a dash
Holding the eyes shut adds a dash. A bar fills as they hold and turns white the moment it counts as a dash, so the patient can feel where the boundary is.
A pause finishes the letter
Stop blinking and the letter completes on its own — nothing to press. Pause a little longer and a space is added between words. A bar under This letter fills green as the pause runs down, and the box beside it shows the letter that will be written.
Speak the answer
When the message is complete, the caregiver presses Speak Answer and the app reads it aloud and saves it to history.
The full alphabet stays on screen the whole time in large tiles. As dots and dashes come in, every letter that can no longer match fades out, and the one currently spelled lights up green — so you can watch the answer narrow down rather than decode it in your head.
While the eyes are closed, the same bar shows the blink itself: blue while it would still be a dot, amber in the gap where it counts as neither, and white once it is long enough to be a dash.
Misread blinks happen. Undo removes the last symbol or letter, Space inserts a word break, and Clear starts over. These are caregiver buttons on purpose — the patient only ever has to do two things.
How long a pause ends a letter is adjustable from the ☰ menu → Letter pause (1 to 3 seconds). This is the single most important setting in Morse mode: if the patient is being cut off mid-letter, make it longer; if waiting between letters feels slow, make it shorter.
A short word takes 20–30 seconds. Morse earns its place when the four options genuinely don't contain the answer — a name, a specific symptom, a request nobody thought to offer — not as the everyday default. If a pattern doesn't match any letter, ReNav drops it and says so rather than guessing at a letter the patient didn't mean.
Using the App
Every conversation follows the same simple flow:
Caregiver asks a question — by voice or by typing
Tap the large microphone button at the bottom of the screen, then clearly speak a question — e.g. "Are you feeling pain anywhere?" or "Would you like some water?" If the room is noisy, or the browser cannot hear you (Firefox has no speech recognition, and Tamil and Hindi recognition can struggle), tap ⌨️ Type instead: type the question, or tap one of the ready-made quick questions — pain, water, food, toilet, changing position, too hot or cold, rest, calling someone.
Four answer options appear — and "None of these"
Within 1–3 seconds, four short personalised answer options appear on the large coloured buttons. The question is displayed at the top of the screen. A fifth button in the middle always reads None of these: if the patient chooses it, ReNav says so aloud, and the caregiver knows to ask the question a different way rather than the patient settling for the closest wrong answer. In Morse mode this step is skipped entirely — the patient begins spelling straight away, with no wait.
Patient answers, in whichever way suits them
Head mode: turn towards the answer to highlight it, then blink once.
Blink mode: short blinks step through the answers, a long blink chooses one.
Morse mode: spell the reply with dots and dashes, then press Speak Answer.
Blinks during playback are ignored
Once an answer is chosen, ReNav stops listening to blinks until it has finished speaking. The patient can blink normally while listening without it being read as a new answer.
The app speaks the answer aloud
ReNav reads the selected answer through the device speakers so everyone in the room can hear the patient's response clearly.
The patient should blink deliberately and fully — a complete eye close and open. Very brief involuntary blinks are filtered out and will not trigger anything. In blink and Morse modes, what separates one gesture from another is how long the eyes stay shut, not how hard the blink is — so encourage a relaxed hold rather than a forceful squeeze.
Calling for Help
Every other part of ReNav starts with a caregiver asking. This is the one thing the patient can start on their own — so they are never stuck waiting for someone to happen to come in and ask.
With no question on screen, two long blinks
The patient closes their eyes and holds, opens them, then does it again within about six seconds. After the first one, a message on screen says to do it once more. A short blink in between cancels it.
A chime sounds and the patient's voice calls out
ReNav plays a chime, says "Please come here. I need you." in the patient's voice and language, and fills the screen with a red alert. It repeats every 15 seconds until someone answers it.
Press "I'm here"
The alert stops when a caregiver presses I'm here, presses Escape, or simply starts asking a question.
Browsers only allow sound after someone has tapped or clicked the page, so tap the screen once after opening the app — any tap will do. Keep the device's volume up and the app open in front. A single long closure, such as falling asleep, never sets it off — it takes two deliberate ones. Calling for help works in head and blink modes; in Morse mode two long blinks spell the letter M, so a Morse patient spells their request instead.
Button Layout
The screen is divided into 4 large quadrants, with a smaller None of these button in the middle. The patient turns their head to point their nose toward a quadrant to highlight it, then blinks to select. Here is the layout:
A small dot on the screen follows the patient's nose position in real time — this is your live feedback that tracking is working. The quadrant the dot is in determines which button is highlighted. After calibration, the mapping accounts for the patient's personal range of head motion automatically.
Resting the head straight ahead, so the dot sits on the middle button, highlights None of these. It only appears once head calibration has been done — before that, the patient's resting position cannot be told apart from a small turn, and the four answers would become hard to reach. In blink mode it is simply the fifth stop after the four answers.
Tips for Best Results
Camera Setup
- Position camera at eye level
- Ensure good lighting on the face
- Avoid strong backlight (window behind)
- Ideal distance: 40–70 cm
- Watch the small camera preview at the bottom
Blink Detection
- Blink deliberately and fully
- Complete eye close and open
- 1.4 s wait enforced between selections
- Clean camera lens if needed
Asking Questions
- Ask one question at a time
- Use simple, clear language
- Be specific for better AI options
- Speak clearly close to the device
Device Setup
- Use Chrome or Edge browser
- Keep device plugged in
- Tablet on a stand — ideal bedside
- Turn volume up before starting
AI Personalisation
ReNav gets smarter the more you use it. Every question asked and every answer the patient selects is saved to their personal profile.
When generating new answer options, the AI reviews the patient's recent interactions to tailor responses specifically to them. For example:
Preference Learning
If the patient frequently selects "I want to watch cricket", that preference will start appearing as an option more often when asked about entertainment or activities.
Pain Pattern Recognition
If the patient often reports pain in a specific area, the AI will offer more targeted pain-related options over time, making selections faster.
More Relevant Options Over Time
The system analyses the patient's last 10 interactions when building each response. Options become more natural and personalised with continued daily use.
AI personalisation is available to every ReNav user at no cost. No subscription or setup needed — it begins automatically from your first session.
Dashboard & History
Access the Dashboard by tapping 📊 Dashboard in the app menu, or visiting /dashboard/. It shows the patient's full communication history.
Full Communication History
Every question asked and the answer the patient selected, with timestamps. All four options generated for each question are recorded, so you can see what alternatives were offered.
Pagination Controls
Use the per-page selector to view 5, 10, 25, or 50 entries at a time. Useful for quickly reviewing recent sessions or scrolling through older history.
The communication history is valuable for doctors and nurses — it reveals the patient's needs, pain patterns, and daily wellbeing over time. Share the dashboard with your care team during consultations.
Troubleshooting
| Problem | Solution |
|---|---|
| Camera not turning on | Click the camera icon in your browser's address bar and allow access, then refresh the page. |
| Buttons not highlighting | Ensure the face is clearly visible in the camera preview. Improve room lighting. Move the device closer. Try recalibrating from the ☰ menu. |
| Nose ball jumps around | Improve face lighting and reduce background movement. Keep the camera steady. Recalibrate if the patient's position has changed. |
| Blinks not being detected | Ensure the patient performs a full, deliberate blink. Clean the camera lens. Check that the face is well lit from the front. |
| Accidental selections | The patient may be blinking too casually. Encourage more deliberate, slow blinks. Avoid bright sunlight or flickering light falling directly on the face. |
| Left and right are swapped | Head mode only, and almost always because calibration has not been completed. Run a full calibration from the ☰ menu — the calibration itself works out which way round the camera is. |
| Long blink is tiring, or too slow | Set ☰ menu → Blink speed to Fast. If short blinks then start registering as long ones, go back to Normal. |
| Short blinks are being read as long ones | Set ☰ menu → Blink speed to Relaxed, which widens the gap between the two gestures. |
| Blink or Morse gestures do nothing | Run the blink check from the mode's setup screen. If the room lighting has changed since the last session, the detection baseline needs re-measuring. |
| Morse: letters end before the patient is finished | Increase ☰ menu → Letter pause. A slower blinker needs a longer pause, not a different mode. |
| Morse: "Not a letter" keeps appearing | The dots and dashes did not match any character, so ReNav discarded them rather than guessing. Check the chart — the tile that lights up green is what is currently spelled. Undo and try the letter again. |
| Mic is disabled after an answer | Normal — ReNav ignores input while it speaks the answer, then re-enables it. If it stays disabled for more than a few seconds, refresh the page. |
| Microphone not working | Allow microphone permission in browser settings. Check the device microphone is not muted. Try Chrome or Edge. You can always tap ⌨️ Type to type the question or pick a quick question instead. |
| The call for help was not heard | Tap the screen once after opening the app — browsers block sound until the page has been touched. Keep the volume up and the app open in front. |
| Options not loading | Check your internet connection. The AI requires internet access to generate answer options. |
| Tracking feels misaligned | Open ☰ menu → Calibrate and redo the 5-point calibration. This is the most effective fix for gaze drift. |
| No sound when answer selected | Check device volume is turned up. Ensure the device is not on silent mode. Tap the screen once to unlock audio autoplay, then try again. |
| App says "Best on a Larger Screen" | The eye-tracking app requires a screen at least 1024 px wide and 600 px tall. Use a laptop, desktop, or large tablet in landscape mode. |
Patient Face Check
On a paid plan, the app can learn the patient's face so it knows whether the patient is the one facing the camera. It never stops anyone answering and never changes the plan — it only notes who is in view. Institution plans are not checked — they serve many patients.
Set it up once
Make sure only the patient is in view, in good light. Tick the consent box and press Start Face Check. The patient looks at the camera for a few seconds. In Head mode they are also asked to turn the head a little each way; in Blink and Morse modes they are never asked to move.
Nothing to do after that
While the app is open it quietly checks the camera every few minutes, only when nothing is being answered. A caregiver in view beside the patient is fine.
If the patient is not recognised
Nothing changes: answers, languages and every paid feature keep working. A 👤 badge appears in the header to say the camera does not see the patient; it goes away by itself once it does. Tap the badge to check straight away.
A new face, once a month
If the patient's appearance changes, or you move to a new camera, set the face up again from Menu → Face check. This is possible once a month; if you need it sooner, or the camera cannot recognise the patient at all, contact us and we will sort it out.
ReNav keeps numbers that describe the face, never a photo or video. You can delete them at any time from the dashboard.
Privacy & Security
Camera data stays on your device
Video is never uploaded or stored. Only the nose position coordinates and a blink signal are processed — all face analysis happens locally in the browser using MediaPipe. On paid plans the face check sends numbers that describe the face, never a picture.
Encrypted communication
All data between your device and the ReNav server is encrypted via HTTPS. Your conversations are private and cannot be intercepted.
Free to start
The free tier includes five AI questions a day, and Morse mode is unlimited on every plan. Paid plans lift the daily cap and pay for the servers and AI inference that keep the service running.
Your data is never sold
Patient communication history is stored solely to power AI personalisation for that patient. It is never shared with third parties or used for advertising.
What it costs
Free. Five AI-generated question sets a day, all three input modes, and your full answer history. No card, no trial that expires.
Morse mode is free forever, on every plan. When the patient spells their own answer there is no AI call to pay for, so we do not meter it. It is also the only mode some patients can use, and we are not willing to put that behind a payment. If you run out of AI questions for the day, switch to Morse and the patient can still say whatever they want.
Care — ₹899 a month, or ₹8,999 a year (two months free) — removes the daily cap and adds Tamil and Hindi, spoken on any device. The free plan is in English. There is no checkout on this site: you write to us, we tell you how to pay, and we switch your account over by hand, usually within a day. Nothing auto-renews, because we hold no card.
Ready to get started?
Create a free account — it takes a couple of minutes.