Low Frequency Spectrum Analyzer for Automotive Suspension Analysis

This project is an accelerometer data acquisition system for automotive suspension analysis. In other words it’s a low frequency spectrum analyzer based on Lanchpad TIVA Series from Texas Semiconductors.

Description

It’ s a spectrum analyzer for mechanical frequencies (max. 50 Hz). In my application I use this analyzer for the signals from a suspension of a car, that contain information about comfort (ride) of a vehicle.

The system is based in 3 parts:

• the GUI (user interface),
• the hardware (core is a LM4F120 that is an ARM of Texas Instruments) and
• accelerometers (in my case, needed for vibration analysis).

The hardware contains two voltage regulators (3.3V, 5V), 8 connectors for AD, 1 channel for serial protocol, 1 channel for Bluetooth, and one reset button. System status is displayed using three LEDs and a one LED is for 5V power supply indication.

The main component is the ARM processor. The firmware, contains a FIR low pass filter with 75 Hz cutoff frequency , sample frequency is 512 Hz, 256 points FFT and Power Density Spectrum based on Welch Method.

The accelerometers used are 4x ADXL 335 (+/- 3g) and 4x ADXL 325 (+/- 2g) with 3V supply voltage.

Schematic

connection of ADXL335 to MCU

Photos

3D PCB rendering

manufactured PCB

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