From silence to service: a wearable visual-haptic task coordination framework for deaf and hard-of-hearing restaurant...

Communication practices based on spoken instructions and auditory alerts can limit the participation of deaf and hard-of-hearing employees in fast-paced restaurant environments. This study developed a low-cost wearable multimodal framework to support operational communication through visual and haptic notifications.

The framework integrates a smartwatch-style wearable device, Message Queuing Telemetry Transport (MQTT) messaging, a web-based ordering platform, and a kitchen-management interface within a local Wi-Fi network. The system enables assigned employees to receive, acknowledge, perform, and complete delivery tasks through accessible notification channels. Technical evaluation included task synchronization, communication range and latency, battery performance, thermal safety, and server performance.

The system demonstrated reliable task synchronization across three wearable devices and maintained communication over distances of up to 30 m. Average battery runtimes were 162-168 min, while rear-surface temperatures remained between 30.1 and 30.5 °C. The server also maintained stable performance under simulated workloads. The prototype hardware cost approximately IDR 291,500, indicating the potential for relatively low-cost implementation.

The proposed framework demonstrates the technical feasibility of using visual and haptic wearable notifications for restaurant task coordination without relying exclusively on spoken instructions or auditory alerts. However, because deaf and hard-of-hearing restaurant employees were not included in the evaluation, the findings do not establish accessibility effectiveness or workplace benefits. Participatory co-design and field testing with intended users are required to evaluate its practical accessibility, usability, and workplace impact.