AHRS (attitude and heading reference systems)
IMU (inertial measuring units)
consisting of sensors on three axes that provide attitude information:
(1) gyroscope (2) accelerometer (3) magnetometer
Accelometer, Gyro & IMU Sensors (x-OSC Board User Manual)
x-OSC is a wireless I/O board that provides just about any software with access to 32 high-performance analogue/digital channels and on-board sensors (gyroscope, accelerometer, magnetometer) via OSC messages over WiFi. There is no user programmable firmware and no software or drivers to install making x-OSC immediately compatible with any WiFi-enabled platform. All internal settings can be adjusted using any web browser.
- 16× analogue/digital inputs
- 16× digital/PWM outputs (up to 50 mA per channel)
- 13-bit ADC with 400 Hz update rate per channel
- Up to 16-bit PWM resolution for 5 Hz to 250 kHz
- Control up to 400 RGB LEDs (NeoPixel)
- 4× serial communication channels
- Gyroscope (±2000°/s), accelerometer (±16 g) and magnetometer
- 400 Hz update rate
- High-performance WiFi (802.11b/g, 54 Mbps)
- Supports ad-hoc and infrastructure networks
- Fully configurable by web browser
- Regulated 3.3 V output
- Battery level monitor
- Size: 45 × 32 × 10 mm
OSC Open Sound Control (source)
Open Sound Control (OSC) is a protocol for communication among computers, sound synthesizers, and other multimedia devices that is optimized for modern networking technology. Bringing the benefits of modern networking technology to the world of electronic musical instruments, OSC's advantages include interoperability, accuracy, flexibility, and enhanced organization and documentation.
This simple yet powerful protocol provides everything needed for real-time control of sound and other media processing while remaining flexible and easy to implement.
- Open-ended, dynamic, URL-style symbolic naming scheme
- Symbolic and high-resolution numeric argument data
- Pattern matching language to specify multiple recipients of a single message
- High resolution time tags
- "Bundles" of messages whose effects must occur simultaneously
- Query system to dynamically find out the capabilities of an OSC server and get documentation
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Extra Info from Live Science (source)
A gyroscope is a device that uses Earth’s gravity to help determine orientation. Its design consists of a freely-rotating disk called a rotor, mounted onto a spinning axis in the center of a larger and more stable wheel. As the axis turns, the rotor remains stationary to indicate the central gravitational pull, and thus which way is “down.”
What is an accelerometer?
An accelerometer is a compact device designed to measure non-gravitational acceleration. When the object it’s integrated into goes from a standstill to any velocity, the accelerometer is designed to respond to the vibrations associated with such movement. It uses microscopic crystals that go under stress when vibrations occur, and from that stress a voltage is generated to create a reading on any acceleration. Accelerometers are important components to devices that track fitness and other measurements in the quantified self movement.
Uses of a gyroscope or accelerometer
The main difference between the two devices is simple: one can sense rotation, whereas the other cannot. In a way, the accelerometer can gauge the orientation of a stationary item with relation to Earth’s surface. When accelerating in a particular direction, the accelerometer is unable to distinguish between that and the acceleration provided through Earth’s gravitational pull. If you were to consider this handicap when used in an aircraft, the accelerometer quickly loses much of its appeal.
The gyroscope maintains its level of effectiveness by being able to measure the rate of rotation around a particular axis. When gauging the rate of rotation around the roll axis of an aircraft, it identifies an actual value until the object stabilizes out. Using the key principles of angular momentum, the gyroscope helps indicate orientation. In comparison, the accelerometer measures linear acceleration based on vibration.
The typical two-axis accelerometer gives users a direction of gravity in an aircraft, smartphone, car or other device. In comparison, a gyroscope is intended to determine an angular position based on the principle of rigidity of space. The applications of each device vary quite drastically despite their similar purpose. A gyroscope, for example, is used in navigation on unmanned aerial vehicles, compasses and large boats, ultimately assisting with stability in navigation. Accelerometers are equally widespread in use and can be found in engineering, machinery, hardware monitoring, building and structural monitoring, navigation, transport and even consumer electronics.
The appearance of the accelerometer in the consumer electronics market, with the introduction of such widespread devices like the iPhone using it for the built-in compass app, has facilitated its overall popularity in all avenues of software. Determining screen orientation, acting as a compass and undoing actions by simply shaking the smartphone are a few basic functions that rely on the presence of an accelerometer. In recent years, its application among consumer electronics extends now to personal laptops.
Sensors in use
Real-world usage best illustrates the differences between these sensors. Accelerometers are used to determine acceleration, though a three-axis accelerometer could identify the orientation of a platform relative to the Earth’s surface. However, once that platform begins moving, its readings become more complicated to interpret. For example, in a free fall, the accelerometer would show zero acceleration. In an aircraft performing a 60-degree angle of bank for a turn, a three-axis accelerometer would register a 2-G vertical acceleration, ignoring the tilt entirely. Ultimately, an accelerometer cannot be used alone to assist in keeping aircrafts properly oriented.
Accelerometers instead find use in a variety of consumer electronic items. For example, among the first smartphones to make use of it was Apple’s iPhone 3GS with the introduction of such features as the compass app and shake to undo.
A gyroscope would be used in an aircraft to help in indicating the rate of rotation around the aircraft roll axis. As an aircraft rolls, the gyroscope will measure non-zero values until the platform levels out, whereupon it would read a zero value to indicate the direction of “down.” The best example of reading a gyroscope is that of the altitude indicator on typical aircrafts. It is represented by a circular display with the screen divided in half, the top half being blue in color to indicate sky, and the bottom being red to indicate ground. As an aircraft banks for a turn, the orientation of the display will shift with the bank to account for the actual direction of the ground.
The intended use of each device ultimately influences their practicality in each platform used. Many devices benefit from the presence of both sensors, though many rely on the use of but one. Depending on the type of information you need to collect — acceleration or orientation — each device will provide different results.