Inertial Measurement Unit
Inertial Measurement Unit - Related Videos
03:38
Measurement: Standard Units
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2020
Every measurement provides three kinds of information: the size or magnitude of the measurement (a number), a standard of comparison for the measurement (a unit), and an indication of the uncertainty of the measurement. While the number and unit are explicitly represented when a quantity is written, the uncertainty is an aspect of the errors in the measurement results. The number in the measurement can be represented in different ways, including decimal form and scientific notation, which is...
03:02
Measurement: Derived Units
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2020
The International System of Units or SI system, by international agreement, has fixed measurement units for seven fundamental properties: length, mass, time, temperature, electric current, amount of substance, and luminosity. These are called the SI base units. Units of measurement derived from the mathematical combination of SI base units are called SI-derived units. For example, the ratio of the SI unit for distance (meter; m) and the SI unit for time (second; s) gives the SI-derived unit...
01:27
Units of Measurement
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2023
Mechanical engineering is one of the oldest branches of engineering. It deals with designing, analyzing, and manufacturing machines and mechanical systems. To ensure precise and accurate calculations, units of measurement are used. They provide a standard system for expressing and comparing physical quantities. There are various well-known historical measurement systems, such as the Babylonian system, the Roman system, the Egyptian system, the Olympian system, the British system, and the Indus...
06:52
An Inertial Measurement Unit Based Method to Estimate Hip and Knee Joint Kinematics in Team Sport Athletes on the Field
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Cited by 31 •
2020
Monitoring athletes is essential for improving performance and reducing injury risk in team sports. Current methods to monitor athletes do not include the lower extremities. Attaching multiple inertial measurement units to the lower extremities could improve monitoring athletes in the field.
01:10
Units and Standards of Measurement
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2023
A physical quantity is defined either by specifying its measurement method or by stating how it is calculated from other measurements. For example, consider a metallic cube. We might define its mass and dimensions by specifying methods for measuring them, such as using a weighing machine and a meter scale. Then, we could define the volume by stating that it is the cube of its side, and we could calculate the density as the mass divided by the volume. Measurements of physical quantities are...
FAQs
Calibration establishes corrections for sensor bias and noise before the processor interprets measurements. This matters because even small errors become increasingly significant when acceleration and angular velocity are integrated over time. In engineering systems, calibration supports more reliable estimates of orientation and movement, particularly during extended operation without GPS or another external reference.
Integration converts measured acceleration and angular velocity into estimates of changing velocity, position, and orientation. Any bias or noise in those measurements is carried into later calculations, allowing error to accumulate rather than remain constant. This drift limits standalone accuracy and explains why engineers often combine IMU output with GPS, cameras, or magnetometers.
Sensor fusion combines inertial measurements with information from an external reference, such as GPS, a camera, or a magnetometer. The additional information helps constrain errors that grow during integration and improves the estimated motion or orientation. This approach is especially valuable when an application needs more dependable results than the inertial signals can provide alone.
A typical processing sequence begins with calibration, followed by interpretation of accelerometer and gyroscope signals along their measurement axes. The processor then integrates the data to estimate movement and orientation and may apply sensor-fusion algorithms when external measurements are available. The resulting estimates can support navigation, motion analysis, stabilization, or guidance.
An IMU is particularly useful when external references are unavailable, intermittent, or insufficient for continuous motion tracking. Its measurements can support aircraft, spacecraft, robots, vehicles, and smartphones, as well as systems that analyze or stabilize motion. Because drift can increase over time, engineers may combine the unit with other sensors when sustained accuracy is important.
The processor’s estimates of orientation and movement provide information that engineering systems can use to assess how an object is rotating or translating. That information supports stabilization and guidance in platforms ranging from aircraft and spacecraft to robots and vehicles. The quality of these functions depends on calibration, integration behavior, and whether external references reduce accumulated drift.