Sentinel HMD-1

Program intent

Sentinel HMD-1 is a head-mounted display system developed for low-signature environments where commercial off-the-shelf solutions impose unacceptable signature, weight, or interface compromises. The B01 revision represents the first architecture stable enough for external evaluation - the optical geometry is validated, the firmware interface is documented, and the display module can be replaced without tools.

The program is not attempting to compete with volume production HMD programmes. The intent is to establish a documented, serviceable architecture that can be adapted for specific operational contexts - and to demonstrate that this is possible at low volume with the right design discipline.

Architecture

The Sentinel HMD-1 is built around three independently serviceable modules:

• Display module - single-cable (USB-C) connection, hot-swappable under power, standard mounting geometry
• Optical stack - fixed geometry, validated and documented, minimal adjustment points (by design)
• Processing unit - off-the-shelf compute platform with a thin firmware layer; interface is published and version-controlled

The single-cable architecture reduces connector count and failure modes. Power and data run on the same cable - a deliberate departure from dual-bus designs that add weight and maintenance complexity with marginal benefit at this form factor.

Firmware and interface

The firmware interface is documented using a simple JSON-over-serial protocol. This was chosen over a proprietary binary protocol to make integration legible without specialised tooling. The ICD is version-controlled alongside the hardware revision history. Any firmware change that alters the interface results in a minor revision increment and a delta document.

Current status

The B01 architecture is in active development. Optical validation is complete. Weight and ambient light rejection targets are not yet confirmed - they are listed as TARGET claims and will be updated to VERIFIED as test data accumulates. Evaluation units are not yet available; scheduled briefings and capability documentation are available for prime contractor and evaluator review on request.