Performance & calibration

An angular frame is a representation of an object’s orientation in 3D space. It is commonly described using Euler angles or a quaternion. Please see http://en.wikipedia.org/wiki/Euler_angles and http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation.

An angular frame does not describe the 3D location of an object, only its rotation relative to a reference. The reference rotation for a 6-axis angular frame is flat and level—that is, the vertical axis of the object is aligned with up/down. The reference rotation for a 9-axis angular frame is flat, level, and north: the vertical axis of the object is aligned up/down, and the forward axis of the object is aligned north/south.

A quaternion represents a rotational frame in a form related to the angle theta and axis v of rotation, where v is a three-dimensional unit (length 1) vector, and q = sin (theta / 2) + i * vx * cos(theta/2) + i * vy * cos(theta/2) + k * vz * cos(theta/2)

You can easily convert a quaternion to Euler angles or a rotation matrix.

http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation

The DMP calculates the MotionFusion solution as a quaternion because it is the most efficient representation for mathematical applications.

Both accelerometers and magnetometers are noisy sensors, which means they exhibit a slow response rate (due to noisy filtering) in fast moving systems. Accelerometer measurements are also affected by motion. By using a gyroscope and sensor fusion, the sensor fusion solution will have a faster response rate and track small, quick movements much more quickly. Gyroscope sensor fusion also makes it possible to sense linear acceleration separately from gravity.

Click Products at the top of the main page. There will be various MEMS product lines like Motion, Industrial, Automotive, Microphone, and Ultrasonic/ToF etc.  You can choose the desired area and that will take you to the product families and components. Once you click through to a product page for a specific component, you will find all the necessary information toward the end of the page. 

Euler angles are a representation of an angular frame, as are quaternions and rotation matrices.

Euler angles are a set of three angles, corresponding to pitch, roll, and yaw.

Euler angles may be constructed according to many conventions. The axes of and ordering of ordering of pitch, roll, and yaw vary by convention. The Embedded MotionApps Platform makes Euler angles available in the three most common conventions with MLGetEulerAnglesX, MLGetEulerAnglesY, and MLGetEulerAnglesZ. See the Embedded MotionApps Platform Functional Specification for specific details on the definition of these conventions.

Euler angles are not commutative. For any Euler angles A, B, a rotation A followed by B is not (B + A) is necessarily equal a rotation B followed by A (B + A). Because of this algebraic property, Euler angles are often not very useful for signal processing applications.

Euler angles suffer from a pair of singularity points at which only two of the three angles are significant. The derivative of the Euler angles is discontinuous at this point. This condition is often called gimbal lock.

The Embedded MotionApps Platform reference implementation for the Atmel UC3-A3 Xplained board takes 40k total program (ROM) memory and about 3K of data memory.
MotionFit SDK: 90kB
Motion Driver: 32kB total, 13kB for driver+DMP image

Embedded MotionApps Platform provides a gyro bias tracker “ML_BIAS_FROM_NO_MOTION” which finds the gyro bias after an eight second period without motion.

A pair of gyro bias trackers “ML_LEARN_BIAS_FROM_TEMPERATURE” and “ML_BIAS_FROM_TEMPERATURE” allow the Embedded

The Algorithms for sensor fusion is InvenSense IP, and runs in encrypted form on the DMP or as a binary on the host. Sensor fusion outputs quaternions, which is a 3D representation of the movement of an object in space. As long as the Application is using quaternions, there is no need for the system developer to get burdened with the details of sensor fusion implementation.

The calibration algorithms that are supported in software are No Motion Cal, whenever the Gyro detects a no motion event through the DMP, it immediately triggers a calibration process. There is also a temperature compensation of the Biases, which runs in software on the micro. These calibration routines run in real time on the hardware and micro, and does not need any external equipment.