LOW COST FULLY CONFIGURABLE VIBRATION METER BASED ON ACCELEROMETERS

Resumo

A vibration meter is an instrument used in civil and mechanical engineering to measure the vibration of structures such as buildings, roads, bridges, rotating machines and pipe vibrations in industrial installations. There are equipment and systems capable of performing vibration and oscillation measurements in the market, but they are very expensive and they are in general available in a closed form, where the user has limited chance to configure the parameters and adapt for the target application. The proposed system is composed of six three-axes accelerometers, in which it is possible to measure acceleration in x, y and z coordinates. Each sensor can be activated or disactivated according to the needs of each application. The implementation of a new system to measure vibration and oscillation aims to offer an alternative tool, providing low cost, full customization and adequate precision. The implemented system consists basically of six accelerometers, a microcontroller, two communication interfaces, a Real Time Clock (RTC) module and a Bluetooth module. The acceleration data are collected through six MPU 6050 accelerometers, with provide linear acceleration on the x, y and z axes. The six sensors can be turned on or off according to the needs of each application through switches. The sensors are read and configured by PAMPIUM microcontroller, which processes the linear acceleration information delivered by the accelerometers and the correspondent time information provided by a RTC module, and send them to a computer. The communication between the sensors and PAMPIUM is made through the I2C communication protocol. The communication between the PAMPIUM and the Bluetooth interface is implemented with the RS-232 communication protocol. Finally, the communication with the computer happens through the Bluetooth protocol. In order to verify the functioning of the implemented system for wide amplitude oscillation, we performed a simple test with an inverted pendulum. This was done by attaching the accelerometer sensor to the extremity of the rod and placing the pendulum in oscillatory motion. With the acceleration and time data obtained from the implemented system, it is possible to reproduce the signal of the pendulum oscillatory motion. The communication between the implemented system and the computer is wireless, through the Bluetooth protocol, providing an easy connection for transmitting data. The design is fully configurable and includes the dedicated microcontroller implemented in FPGA. It allows the communication interfaces, as well as the activation switches of the sensors, to be connected directly to the microcontroller register bank, thus facilitating the implementation of the control protocols. The implemented system can be fully customizable, allowing the configuration on the number of active sensors. The implemented system presents low cost and easy maintenance.