Gyrosensors

Gyro sensors, also known as angular rate sensors or angular velocity sensors, are devices that sense angular velocity.

Angular velocity

In simple terms, angular velocity is the change in rotational angle per unit of time.
Angular velocity is generally expressed in deg/s (degrees per second).

Gyro Sensor Types

Gyro sensors come in a variety of types. Here, different types are plotted by size and performance.

 

In recent years vibration gyro sensors have found their way into camera-shake detection systems for compact video and still cameras, motion sensing for video games, and vehicle electronic stability control (anti-skid) systems, among other things.

Moving forward, demand for vibration gyros is expected to grow in areas such as vehicle driver safety and support systems, and in robot motion control.

Vibration Gyro Sensors

Vibration gyro sensors sense angular velocity from the Coriolis force applied to a vibrating element. For this reason, the accuracy with which angular velocity is measured differs significantly depending on element material and structural differences. Here, we briefly describe the main types of elements used in vibration gyro sensors.

Types of elements used in vibration gyro sensors

Vibration gyro sensor manufacturers are using a variety of materials and structures in an effort to devise compact, high-accuracy gyro sensors that have good characteristics, including: 
 · scale factor
 · temperature-frequency coefficient
 · compact size
 · shock resistance
 · stability
 · noise characteristics

	Material	Sample Structure
Piezoelectric transducer
	Ceramic
Silicon transducer	Silicon	Si MEMS NOTE: Every company uses a different structure.

How Angular Velocity Sensing Works (in Vibration Gyro Sensors)

Vibration gyro sensors sense angular velocity from the Coriolis force applied to a vibrating object.
Here, we explain how this works, using as an example Epson 's double-T structure crystal element.

1. Normally, a drive arm vibrates in a certain direction.		2. Direction of rotation		3. When the gyro is rotated, the Coriolis force acts on the drive arms, producing vertical vibration.
		5. The motion of a pair of sensing arms produces a potential difference from which angular velocity is sensed. The angular velocity is converted to, and output as, an electrical signal.		4. The stationary part bends due to vertical drive arm vibration, producing a sensing motion in the sensing arms.

Gyro Sensor Applications

There are three main applications for gyro sensors.

Sense the amount of angular velocity produced.

Used in measuring the amount of motion itself.

Ex.) Checking athletic movement

Senses angular velocity produced by the sensor's own movement. Angles are detected via integration operations by a CPU.

The angle moved is fed to and reflected in an application.

Ex.) Car navigation systems
Game controllers
Cellular

Senses vibration produced by external factors, and transmits vibration data as electrical signals to a CPU.

Used in correcting the orientation or balance of an object.

Ex.) Camera-shake correction
Vehicle control

Interesting facts
Examples of angular velocity in applications:
 · Car navigation systems: ~10 deg/s
 · Vehicle control: ~30 deg/s
 · Camera-shake correction: ~100 deg/s
 · Game controllers: ~300 deg/s
 · Sensing the swing of golf's top players: ~3,000 deg/s

Raspberry Pi

The normal computing world has gone smaller unlike the old times when a single computer spanned across a whole room. In the 21st century the most recent and groundbreaking invention in the field of computing is that of the "Raspberry pi".

The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It is a capable little computer which can be used in electronics projects, and for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. We want to see it being used by kids all over the world to learn how computers work, how to manipulate the electronic world around them, and how to program.

Specifications

	Model A	Model B	Model B+
Target price:	US$25	US$35
SoC:	Broadcom BCM2835 (CPU, GPU, DSP, SDRAM, and single USB port)
CPU:	700 MHz ARM1176JZF-S core (ARM11 family, ARMv6 instruction set)
GPU:	Broadcom VideoCore IV @ 250 MHz OpenGL ES 2.0 (24 GFLOPS) MPEG-2 and VC-1 (with license]), 1080p30 h.264/MPEG-4 AVC high-profile decoder and encoder
Memory (SDRAM):	256 MB (shared with GPU)	512 MB (shared with GPU) as of 15 October 2012
USB 2.0 ports:[	1 (direct from BCM2835 chip)	2 (via the on-board 3-port USB hub)	4 (via the on-board 5-port USB hub)
Video input:	15-pin MIPI camera interface (CSI) connector, used with the Raspberry Pi Camera Addon
Video outputs:	Composite RCA (PAL and NTSC) –in model B+ via 4-pole 3.5 mm jack, HDMI (rev 1.3 & 1.4),[raw LCD Panels via DSI 14 HDMI resolutions from 640×350 to 1920×1200 plus various PAL and NTSC standards.
Audio outputs:	3.5 mm jack, HDMI, and, as of revision 2 boards, I²S audio (also potentially for audio input)
Onboard storage:	SD / MMC / SDIO card slot (3.3 V card power support only)		MicroSD
Onboard network:	None	10/100 Mbit/s Ethernet (8P8C) USB adapter on the third/fifth port of the USB hub
Low-level peripherals:	8× GPIO,UART, I²C bus, SPI bus with two chip selects, I²S audio +3.3 V, +5 V, ground		17× GPIO
Power ratings:	300 mA (1.5 W)	700 mA (3.5 W)	600 mA (3.0 W)
Power source:	5 V via MicroUSB or GPIO header
Size:	85.60 mm × 56 mm (3.370 in × 2.205 in)– not including protruding connectors
Weight:	45 g (1.6 oz)

History :

In 2006, early concepts of the Raspberry Pi were based on the Atmel ATmega644 microcontroller. Its schematics and PCB layout are publicly available.Foundation trustee Eben Upton assembled a group of teachers, academics and computer enthusiasts to devise a computer to inspire children. The computer is inspired by Acorn's BBC Micro of 1981.Model A, Model B and Model B+ are references to the original models of the British educational BBC Micro computer, developed by Acorn Computers.The first ARM prototype version of the computer was mounted in a package the same size as a USB memory stick.It had a USB port on one end and an HDMI port on the other.

The Raspberry Pi Components :

The Raspberry Pi device looks like a motherboard, with the mounted chips and ports exposed (something you'd expect to see only if you opened up your computer and looked at its internal boards), but it has all the components you need to connect input, output, and storage devices and start computing.

You'll encounter two models of the device:Model A and Model B. The only real differences are the addition of Ethernet and an extra USB port on the more expensive Model B.

Here are the various components on the Raspberry Pi board:

• ARM CPU/GPU -- This is a Broadcom BCM2835 System on a Chip (SoC) that's made up of an ARM central processing unit (CPU) and a Videocore 4 graphics processing unit (GPU). The CPU handles all the computations that make a computer work (taking input, doing calculations and producing output), and the GPU handles graphics output.
• GPIO -- These are exposed general-purpose input/output connection points that will allow the real hardware hobbyists the opportunity to tinker.
• RCA -- An RCA jack allows connection of analog TVs and other similar output devices.
• Audio out -- This is a standard 3.55-millimeter jack for connection of audio output devices such as headphones or speakers. There is no audio in.
• LEDs -- Light-emitting diodes, for all of your indicator light needs.
• USB -- This is a common connection port for peripheral devices of all types (including your mouse and keyboard). Model A has one, and Model B has two. You can use a USB hub to expand the number of ports or plug your mouse into your keyboard if it has its own USB port.
• HDMI -- This connector allows you to hook up a high-definition television or other compatible device using an HDMI cable.
• Power -- This is a 5v Micro USB power connector into which you can plug your compatible power supply.
• SD cardslot -- This is a full-sized SD card slot. An SD card with an operating system (OS) installed is required for booting the device. They are available for purchase from the manufacturers, but you can also download an OS and save it to the card yourself if you have a Linux machine and the wherewithal.
• Ethernet -- This connector allows for wired network access and is only available on the Model B.

Many of the features that are missing, such as WiFi and audio in, can be added using the USB port(s) or a USB hub as needed. Next: More details on the device itself and its compatible operating systems.

Accelerometers

An accelerometer is a device that measures proper acceleration ("g-force"). Proper acceleration is not the same as coordinate acceleration (rate of change of velocity). For example, an accelerometer at rest on the surface of the Earth will measure an acceleration g= 9.81 m/s² straight upwards. By contrast, accelerometers in free fall orbiting and accelerating due to the gravity of Earth, will measure zero.

Accelerometers have multiple applications in industry and science. Highly sensitive accelerometers are components of inertial navigation systems for aircraft and missiles. Accelerometers are used to detect and monitor vibration in rotating machinery. Accelerometers are used in tablet computers and digital cameras so that images on screens are always displayed upright. Accelerometers are used in drones for flight stabilisation. Pairs of accelerometers extended over a region of space can be used to detect differences (gradients) in the proper accelerations of frames of references associated with those points. These devices are called gravity gradiometers, as they measure gradients in the gravitational field. Such pairs of accelerometers in theory may also be able to detect gravitational waves.

The purpose of the accelerometer :

Accelerometers in phones

The application of accelerometers extends to multiple disciplines, both academic and consumer-driven. For example, accelerometers in laptops protect hard drives from damage. If the laptop were to suddenly drop while in use, the accelerometer would detect the sudden free fall and immediately turn off the hard drive to avoid hitting the reading heads into the hard drive platter. Without this, the two would strike and cause scratches to the platter for extensive file and reading damage. Accelerometers are likewise used in cars as the industry method way of detecting car crashes and deploying airbags almost instantaneously.

In another example, a dynamic accelerometer measures gravitational pull to determine the angle at which a device is tilted with respect to the Earth. By sensing the amount of acceleration, users analyze how the device is moving.

Accelerometers allow the user to understand the surroundings of an item better. With this small device, you can determine if an object is moving uphill, whether it will fall over if it tilts any more, or whether it’s flying horizontally or angling downward. For example, smartphones rotate their display between portrait and landscape mode depending on how you tilt the phone.

How do accelerometers work?

There are many different ways to make an accelerometer! Some accelerometers use the piezoelectric effect - they contain microscopic crystal structures that get stressed by accelerative forces, which causes a voltage to be generated. Another way to do it is by sensing changes in capacitance. If you have two microstructures next to each other, they have a certain capacitance between them. If an accelerative force moves one of the structures, then the capacitance will change. Add some circuitry to convert from capacitance to voltage, and you will get an accelerometer. There are even more methods, including use of the piezoresistive effect, hot air bubbles, and light.