16
votes
Accepted
In theory, is the position derived from accelerometer absolute?
In theory, is the position derived from accelerometer absolute?
Ok, so imagine you're a sensor. All you can sense is acceleration. You're an accelerometer.
Now you're at rest, or moving at a ...
- 100k
16
votes
Accelerometer readings not consistently increasing during movement
It's quite difficult to move an object manually with steady acceleration. Your experiment of 'just sliding it ... on a table' would be likely to have fairly constant speed. Any slight change in speed, ...
- 174k
12
votes
Accelerometer readings not consistently increasing during movement
Acceleration is the derivative of speed and the second derivate of position.
It is quite unlikely that moving things by hand you could obtain a constant speed, and thus a zero acceleration. As your ...
- 2,184
9
votes
Acceleration when device is on tilt
Your main mistake is in not treating acceleration as a single vector. When the car is at rest, that vector will always be 1 g upwards. Don't look at just the X component of the raw accelerometer ...
- 315k
8
votes
Spikes in raw acceleration data from AC motor
The spikes seem to have a few common heights that are roughly related by factors of 2, which strongly suggests that they are noise-induced single-bit errors in the binary data.
One good way to ...
- 178k
7
votes
Do MEMS accelerometers have a lower frequency limit?
There is no lower limit to the frequency response of the acceleration to output transfer function. As the other answers have said, they detect orientation, which means detecting gravity all the way ...
- 174k
6
votes
Accepted
Are there any "Translation Accelerometer"?
An accelerometer senses XYZ movement
So if it doesn't explicitly say it is a "rotational accelerometer" then it senses XYZ acceleration. In fact "rotational accelerometer" is a strange term, normally ...
- 12.3k
6
votes
How to resolve the drift around the z-axis in an IMU6050 gyroscope?
The accelerometer doesn't see changes in gravity when you rotate around the vertical z-axis, so you can't use it as an input for a complementary filter (or any other filter/algorithm) to compensate ...
- 9,310
6
votes
Accepted
Some basic questions about an accelerometer's unexpected behavior while tilted
The vector magnitude is constant regardless of orientation, but you are applying offsets in one direction which throws off the symmetry.
You can't calibrate away gravity in only one orientation and ...
- 57.3k
6
votes
Do MEMS accelerometers have a lower frequency limit?
From what I recall, some accelerometers use 4_leg capacitive bridges, etched out of the top silicon layers to provide tiny suspended masses that respond to changes in force.
Because capacitance ...
- 35k
6
votes
Accepted
Do MEMS accelerometers have a lower frequency limit?
Capacitive MEMS (yours, probably) and piezo-resistive accelerometers have a DC-response and are almost always DC-coupled, so they can measure down to 0 Hz without problems.
Piezo-electric ...
- 9,310
6
votes
Accepted
ADXL345 Accelerometer data rate vs bandwidth
I think that this is connected to the 'Nyquist–Shannon sampling theorem', which says that for sampling frequency fs, only signals with frequencies lower than fs/2 can be converted without the loss (or ...
- 131
5
votes
Accepted
How to compute acceleration from accelerometer raw data
As far as I understand, you will get the acceleration in [g] on each axis by dividing each of the 3 values you obtained by 256 (because your sensitivity is 256 counts/g).
To avoid any problems with ...
- 448
5
votes
Why am I seeing drift when using Madgwick algorithm to correct for orientation with 9 DOF IMU?
@Olin Lathrop's answer is wrong. Unfortunately, I don't have the reputation to either downvote or comment on his answer. It's curious that he chose to claim that what is being achieved in the paper ...
5
votes
Cheap alternative to an accelerometer
As Chris suggests, a ball tilt switch is the standard cheap approach for detecting orientation. The lowest-cost option appears to be the SW-200D, available for under 5 cents in quantity: This will ...
- 2,641
5
votes
Accepted
Finding an accelerometer
Accelerometers are specified by the maximum accelerations they can measure. You therefore have to calculate what acceleration is represented by moving 2 mm at 2 KHz.
From your description, 2 mm is ...
- 315k
5
votes
MPU6050 accel/gyro noise that behaves strangely - what might be doing this?
@BrianDrummong identified the source of the apparent noise in the accepted answer. Reading one byte at a time over I2C resulted in asynchronous behavior so that the hi and lo bytes corresponded to ...
- 3,489
5
votes
Accepted
Identifying component from i2c trace & obscure SMD marking
This is a Bosch accelerometer, likely the BMA223 or a variant. Key points:
Recommended land pattern has four traces coming out on each of two opposite sides (and two traces on each of the remaining ...
- 2,641
5
votes
Acceleration when device is on tilt
As other answers have stated, the accelerometer provides a three dimensional vector which is the sum of gravity and other acceleration on the car due to the engine, brakes, or other forces acting on ...
- 57.9k
5
votes
Accepted
How is Gyro drift error related to error in velocity and position?
In a typical pure inertial nav solution, you must cancel out the acceleration due to gravity by subtracting it out. If the vehicle's down vector is incorrect, this error appears as a lateral ...
- 47.1k
5
votes
What is the meaning of output of an accelerometer
When the sensor is horizontal (back of the PCB flat on a level table) with the package of the chip "up" (so you can read the printing on the chip) the Z axis should read about +1g and the X and Y ...
5
votes
Do MEMS accelerometers have a lower frequency limit?
Such a lower limit would not make much sense and would render the device unusable for detecting the orientation.
A MEMS accelerometer will (typically) output the acceleration from Earth's gravity when ...
- 14.6k
5
votes
Do MEMS accelerometers have a lower frequency limit?
I've looked at datasheets for accelerometers before, and checked a couple just now to be sure.
I don't remember seeing a lower limit for detection frequencies - the spot check confirms this.
As you ...
- 73.6k
5
votes
Accepted
Noob questions about my accelerometer (ADXL345) and Arduino components in general
ADLX345 is a chip manufactured by Analog Devices. What you bought is a module that contains that chip, and many other manufacturers make different modules which contain the same chip, but they might ...
- 172k
5
votes
How to get the velocity with an acceleration sensor (ADXL345)?
It is possible, but, as stated in this answer and in the links below, the errors can make the results somewhat inaccurate, and as such it is not advisable to use solely an ADXL345 to calculate ...
- 2,145
5
votes
Accelerometer readings not consistently increasing during movement
The readings are probably correct.
9.8 is a large acceleration, like dropping something from the table. Were you moving it that quickly?
An object moving at constant velocity is not accelerating (...
- 7,941
4
votes
Identify an Accelerometer in an Xfinity XR11 Remote
Okay, after much digging it is a BMA222E. I got hung up on a specific pin layout of 12 pin LGA packages, but I focused instead on the size of the package (thanks chris-stratton for making that ...
- 279
Only top scored, non community-wiki answers of a minimum length are eligible