PIMORONI MSA301 3DoF Motion Sensor Breakout

Tracking the position of an object is an important engineering problem that finds many application areas including military, industrial, medical, and consumer

applications [1 – 3]. This problem is effectively solved with an Inertial Measurement Unit (IMU). An IMU consists of three orthogonally placed accelerometers and gyroscopes, and these sensors find the linear acceleration and angular velocity of the object that it is mounted on. Knowing linear acceleration and angular velocity in three dimensions is enough to track the motion of the system with the help of additional mathematical operations [1, 2]. Compared to other sensing mechanisms, capacitive type sensing sensors have realized intensive research interest due to their advantages such as high sensitivity, high reliability, low temperature

dependence, and low power consumption. The development of MEMS techniques such as bulk and surface micromachining allow to substantially improve the

performance and decrease the cost of the MEMS inertial accelerometers.

There are several reports on the integrated MEMS sensors. In [4], T. Sekiguchi at.al. presented a motion capturing system for human arm motion but integrating two types of sensor, gyroscope and accelerometer. In [5], the accelerometer was integrated in a closed-loop system, in which bandwidth, linearity and dynamic range of the sensor was improved. In another approach, the hybrid integration was reported using CMOS circuit [6]. In this study, we present design and analysis of a three degree-of-free sensor consisting of a 2D accelerometer and a gyroscope for an Inertial Measurement Unit (IMU). The IMU can be employed for tracking in-plane motion, in which the accelerometer and gyroscope are used for measuring two components of linear acceleration and angular velocity with the rotation axis perpendicular to the motion plane, respectively. The integrated partial sensors are modeled and analyzed using SIMULINK model and FEM analysis. The sensors have been designed for measurement in a fully differential capacitive bridge interface based on a sub-fF switched-capacitor integrator circuit.

MSA301 is a triaxial, low-g accelerometer with I2C digital output for consumer applications It has dynamical user selectable full scales range of ±2g/±4g/±8g/±16g

and allows acceleration measurements with output data rates from 1Hz to 500Hz. MSA301 is available in an ultra small (2mmx2mm,height 1mm) LGA package and is guaranteed to operate over -40°C to +85°C.

Specifications

Features:

• Small in size
• Easy to use
• Color: Black
•  I2C Interface
• User selectable data output rate
• One interrupt pins

packages includes:

• 1 x PIMORONI MSA301 3DoF Motion Sensor Breakout