Safety and limitations
What NaviGuider will not do for you
This page is not fine print. It describes the boundary of a tool you may be considering trusting with your body, and it is worth reading before the first walk rather than after a surprising one.
What it is not
- A replacement for a white cane or guide dog.
- A replacement for orientation and mobility training.
- A safety system, a collision-avoidance system, or a medical device.
- A traffic signal reader you can act on without your own judgement.
- Validated for unsupervised travel.
Crossings, specifically
Crossing assistance is the highest-consequence thing in the app and therefore the most restricted. NaviGuider will describe a crossing it has found and report what it has measured about the curb and the tactile paving. It will not tell you a crossing is safe, will not say “go,” and will not infer a signal state it cannot read.
If the app is silent about traffic, that means it does not know about traffic. Silence is never permission.
Detection is not complete
NaviGuider does not detect every obstacle. Overhanging obstacles above the sensor’s field of view, thin poles at certain angles, glass, low-contrast steps, and fast-moving objects are all cases where it may say nothing at all. An absence of warning is not a statement that the path is clear — it is an absence of information.
This is precisely why the cane stays in your hand. The cane covers the failure mode the phone has.
When guidance degrades
In each of these conditions NaviGuider narrows what it claims and says why. The failure mode we design against is confident wrongness, not silence.
- Sensor obstruction
- A coat, a strap, a bag, or a hand across the camera. NaviGuider reports the obstruction rather than guiding from nothing.
- Low light and glare
- Night, tunnels, and low sun into the lens all reduce classification confidence. Camera-only devices are affected more than LiDAR devices.
- Rain, snow, and wet surfaces
- Reflective ground confuses depth. This is the single most common cause of the app narrowing what it claims.
- Crowds and moving obstacles
- Dense pedestrian traffic changes faster than the corridor can be replanned. Guidance becomes less specific.
- Thermal and battery limits
- Sustained navigation warms the device. At thermal limits the app reduces what it claims instead of quietly losing accuracy.
- Network loss
- An active route keeps working from cache. New destinations and re-routes do not, and you are told so.
Using it well
- Keep the cane or the harness in use at all times. NaviGuider is the second source of information, never the first.
- Walk a route you already know before you walk one you do not. You need to hear how the app behaves when you can independently check it.
- Mount the phone on the chest so the camera has a clear forward view, and check that nothing crosses the lens.
- Set verbosity to the level you can actually process while listening to traffic. Less is usually correct.
- Treat every crossing as your decision. The app contributes observations, not permission.
When to stop relying on it
Stop and fall back entirely to your own technique if the app is describing an environment that does not match what your cane is telling you, if it has gone quiet without saying why, or if it is repeating instructions that do not resolve. Report what happened — a contradiction between the app and the cane is the most useful bug we can receive.
Reporting a safety problem
Email nhellyer6@gmail.com with “safety” in the subject. Include where it happened, what the app said, and what was actually there. If you are an orientation-and-mobility specialist, say so — that context changes how we triage it.
More on how the app is being evaluated is in the research program.