Applications and Implications, Project Development

Project Description

The device I am developing is a movement quality wearable designed to monitor human movement patterns in real time. It is worn on the wrist or forearm and combines multiple sensors to detect abnormal movements and monitor basic vital signs during physical activity.

The core principle of the system is the calculation of jerk, which represents the rate of change of acceleration. Two IMUs work together — the LSM6DS3 built into the XIAO nRF52840 Sense and the BNO085 — fusing their readings to produce a more robust estimate. When the calculated jerk exceeds a threshold, the device simultaneously triggers haptic feedback through a DC motor and a visual alert on the 0.91" OLED display. Under normal conditions that same display shows the user's heart rate as measured by the MAX30102, providing physiological context that complements the movement analysis. The device targets three main scenarios: physical rehabilitation monitoring, support for people with neuromotor conditions such as tremors or spasms, and movement quality assessment in athletes.

Background and Prior Work

Before designing this device I identified relevant prior work in the commercial, clinical, and academic space. These references confirm the viability of the jerk-based approach and informed the design decisions I made.

References and Sources

For the development of this project I will draw from technical, software, and academic sources covering the selected hardware, firmware libraries, and the theoretical framework behind the detection algorithm.

System Design

The project involves designing several software and hardware subsystems that work together. Each design deliverable has a specific role within the overall system.

Components, Sources, and Costs

Below is the complete bill of materials for the prototype, including each component's function, intended supplier, and estimated unit cost. Prices reflect single-unit or small-batch purchasing. The PCB cost per unit drops significantly at orders of 10 or more.

Fabrication and Development Processes

Building the prototype will involve electronic design, physical fabrication, and programming. On the hardware side, I will design the schematic and PCB layout in EasyEDA or KiCad and send it to JLCPCB for fabrication in a batch of 5 units. Assembly will include soldering of both SMD and through-hole components. For the enclosure, I will model the geometry in Fusion 360 and print it using FDM — PLA for the rigid parts and TPU for the skin-contact zones.

On the software side, I will develop the firmware in the Arduino IDE with the official nRF52840 BSP, covering I2C bus initialization, individual sensor drivers, the IMU fusion module, the jerk algorithm, and the full alert logic. Once the prototype is assembled, I will carry out a systematic threshold calibration by recording reference movements from different people and activity types.

Evaluation

I will evaluate the device through functional, reliability, and usability tests covering each subsystem. Validation will be carried out both on the workbench and through real wear sessions to confirm that the system meets its stated objectives.

Project Delivery

The project will be delivered physically. The submission will include the fully assembled and functional wearable prototype, ready to be operated and demonstrated in person.