Accelerometer Definition and 163 Threads

An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is acceleration in a fixed coordinate system. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity, straight upwards (by definition) of g ≈ 9.81 m/s2. By contrast, accelerometers in free fall (falling toward the center of the Earth at a rate of about 9.81 m/s2) will measure zero.
Accelerometers have many uses in industry and science. Highly sensitive accelerometers are used in inertial navigation systems for aircraft and missiles. Vibration in rotating machines is monitored by accelerometers. They are used in tablet computers and digital cameras so that images on screens are always displayed upright. In unmanned aerial vehicles, accelerometers help to stabilise flight.
When two or more accelerometers are coordinated with one another, they can measure differences in proper acceleration, particularly gravity, over their separation in space—that is, the gradient of the gravitational field. Gravity gradiometry is useful because absolute gravity is a weak effect and depends on the local density of the Earth, which is quite variable.
Single- and multi-axis accelerometers can detect both the magnitude and the direction of the proper acceleration, as a vector quantity, and can be used to sense orientation (because the direction of weight changes), coordinate acceleration, vibration, shock, and falling in a resistive medium (a case in which the proper acceleration changes, increasing from zero). Micromachined microelectromechanical systems (MEMS) accelerometers are increasingly present in portable electronic devices and video-game controllers, to detect changes in the positions of these devices.

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  1. R

    What is the maximum angle that can be reached by a pendulum in an accelerometer?

    Hi all, I'm new to the forum and figured someone on here would be able to help me out w/ my question. I'm having trouble understanding something regarding an accelerometer. Here's a brief description of an accelerometer taken from an excerpt I read to get you all up to speed on what I'm dealing...
  2. I

    How Do You Calculate Angles from Acceleration Data in Different Motion States?

    Hello, I was wondering is someone can help me please with the mathematics of forces/vectors and acceleration. Now I realize that I have a good deal to learn on the subject but as I am starting out on this venture the challenge is find the right reference,. Hence I need more than just a little...
  3. I

    3 axis accelerometer forces as angles/vectors

    Hello, I have a three axis accelerometer that I am using in project that I am working on and I need to find the angle/vector of the axis’s when the device is not orientated to its designated axis, and when it is accelerating. If I lay the device flat on a horizontal surface and read the...
  4. M

    Accelerometer and Displacement

    Homework Statement In Single Degree of Freedom vibration with harmonic support motion, I have used an accelerometer to measure acceleration of the vibrating system. The frequency of the support motion is sweeped through in order to find the resonant natural frequency of the system. So in...
  5. S

    What Is the Plane's Acceleration Based on Pendulum Shift?

    Homework Statement A pendulum has a length L = 1.04 m, with mass m=0.43 kg at the end. It hangs straight down in a jet plane about to take off as shown by the dotted line in the figure. The jet then accelerates uniformly, and while the plane is accelerating, the equilibrium position of the...
  6. G

    Calculating Head Pan Angle with Accelerometer Measurements

    Hi, please don't hesitate to reply to either of my paragraphs. Or ask for clarification. The first paragraph descibes the basic problem, and the second one is more indepth. I'd be happy if I could get just the first one working. I'm working on a project were a two-axis accelerometer will...
  7. N

    Designing a Cantilever Accelerometer with FEM

    Dear everyone, this is my first post here. Nice to meet you all. Now I have my project to design a catilever which can be used as accelerometer. The current stage is to have the vibration motion of the cantilever formulated using FEM, and then the design parameters can be substituted into the...
  8. M

    Can I Use a 3-Axis Accelerometer to Measure 2 Forces?

    ok, Don't know if this is the right forum, but I'd like some help with this I'm making a project that needs to read acceleration in any direction. I have a 3 axis accelerometer, who's orientation is random, unknown, and changing. So my question is, is it possible to read 2 forces of...
  9. C

    Is Acceleration Measured on the Proof Mass or the Surface?

    correct me if wrong an accelerometer consists of a mass(proof mass). say the proof mass is x kg. The accelerometer sensed the acceleration of the proof mass. suppose the accelerometer reading is y can i say the force acting on the proof mass is x.y? Some theory says that the...
  10. A

    Accelerometer via ball on string

    How would I go about measuring forward acceleration using a free-swinging ball on a stand? Could anyone post a free body diagram or an equation that might describe this?
  11. A

    Solving the Relationship between Accelerometer & Normal Acceleration

    I need help with this say there's a truck travellin at a constant speed along a winding flat road. the car body is connected to the axles with springs. Thus, the car body is assumed to roll at a 10degree angle from the vertical of a horizontal 'roll axis' which is fixed on the axles. An...
  12. C

    Using accelerometer sensor to determine speed of person

    hello, I'm using an accelerometer (ADXL311) which outputs analog voltage in proportion to g's for X and Y axes. I'm trying to use this to manipulate sound when a person is 'running', basically as speed increases above a certain threshold, but having problems with my formulas for speed...
  13. L

    How Does an Accelerometer Help Calculate Plane Takeoff Speed?

    A person dangles her watch from a string while the plane takes off. She notices that the string makes a angle of 25 degrees with respect to the vertical whie the plane accelerates to take off, which takes 19 seconds. What is the takeoff speed of the plane? How do I get started? I think the X...
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