MEMS IMUs for Navigation and Stabilization

MEMS IMUs for Navigation and Stabilization

The need for precise movement detection and orientation tracking is driving innovation across multiple markets, from consumer electronics to UAVs.mems imu navigation As the demand for IMUs grows, advancements in microelectromechanical systems (MEMS) fabrication and sensor fusion continue pushing boundaries for what these tiny sensors can do. Whether assessing existing IMUs or considering an entirely new inertial sensing solution, understanding key operating attributes will help guide system designers toward the best possible performance.

IMUs are the building blocks of navigation and stabilization systems.mems imu navigation They combine accelerometers and gyroscopes to detect changes in velocity, pitch, roll, yaw, and heading. They are a critical part of autonomous systems, providing the data needed to determine location and provide positioning feedback. They are also important for other applications, such as vehicle stability control and rollover detection. Silicon MEMS IMUs are a leading technology for these systems, delivering FOG-like performance at lower SWaP-C (size, weight, power, and cost).

A key characteristic to consider when selecting a MEMS IMU is its in-run bias stability.mems imu navigation This metric indicates how consistent an IMU will be over time, even in the face of external forces. For example, quartz MEMS accelerometers typically offer in-run bias stabilities of less than 1 ug, making them ideal for navigation-grade applications.

Another key attribute to consider is the IMU’s nonlinearity.mems imu navigation This metric indicates how closely an IMU’s output resembles a straight line, with higher values indicating greater linearity. Nonlinearity is particularly important in IMUs, as it contributes to the stability of an IMU’s output when subjected to vibrations and shocks.

For UAVs, MEMS IMUs with low nonlinearity are often preferred for their ability to maintain accuracy in dynamic environments.mems imu navigation Additionally, MEMS IMUs with high output linearity are useful for detecting rapid acceleration changes.

While the primary functions of an IMU are to capture linear and angular acceleration, a magnetometer can add to the IMU’s capabilities by tracking the Earth’s magnetic field. This information is particularly important for UAV applications that require accurate heading, as it can offset inherent gyroscopic errors in these applications.

An IMU without a magnetometer finds its niche in scenarios where only rudimentary orientation data is required. However, such an arrangement may be vulnerable to magnetic interference, limiting its utility.

For these scenarios, a fibre-optic gyroscope (FOG) can provide the gyroscopic performance that MEMS IMUs cannot, including ultra-high accuracy and precision, very low drift and bias instability, as well as a high degree of immunity to magnetic interference. This is why many UAVs use FOGs as their inertial sensors. However, the additional costs associated with FOGs make them impractical for many smaller and mid-sized UAV applications.

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