Sensors Low Limb

Overview

The Sensors Low Limb system is a real-time data acquisition and monitoring interface designed for capturing biomechanical sensor data from the lower limb during gait analysis. The application communicates with sensor hardware via a serial connection (COM port) and displays live readings in both tabular and graphical formats.

System Architecture

The sensor array consists of two types of sensors strategically placed across three lower limb joints (hip, knee, and ankle) and three plantar pressure zones:

Accelerometers — ADXL345 (×3)

Three ADXL345 triple-axis digital accelerometers are mounted at the hip, knee, and ankle joints, measuring acceleration along the X, Y, and Z axes. The ADXL345 is a small, thin, ultralow-power 3-axis accelerometer with high resolution (13-bit) measurement up to ±16g, communicating over SPI or I2C interfaces.

Force Sensitive Resistors — FSR400 (×3)

Three FSR400 pressure sensors are positioned on the foot sole at the forefoot, midfoot, and heel regions. These sensors measure plantar pressure distribution during the gait cycle, providing critical data for foot strike pattern analysis and weight transfer assessment.

Data Acquisition

The data table logs timestamped readings at approximately 250ms intervals. Each record captures 12 data channels: three axes for each of the three accelerometers plus three FSR pressure values, totaling over 10,000 data points per minute of recording.

Real-Time Visualization

The interface includes four waveform charts displaying time-series data from the ADXL345 Hip, Knee, and Ankle sensors (with X, Y, Z axes color-coded), and a combined FSR400 chart showing forefoot, midfoot, and hindfoot pressure signals. The periodic waveform patterns visible in the accelerometer charts are consistent with cyclical gait motion, while the FSR chart captures the sequential heel-strike to toe-off pressure transfer characteristic of normal walking gait.

Application Features

The application provides serial port connectivity management, real-time data streaming and logging to a structured table format, graphical sensor placement diagrams showing the physical location of FSR sensors on the foot sole, and the ability to export data for further analysis.