To test the movement stability of my line following cart. I used the accelerometer of my xperia x8. I will put different loads in my cart. Can you suggest some parameters that i can measure or analyze from the 3 axis accelerometer readings? I will compare the acce reeadings from the different loads. Thank you!
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I am using BNO055 for tracking position and velocity. I am getting the accelerometer readings from the sensor but the readings are not precise. Though the accelerometer is calibrated I am getting some disturbance in readings. I just placed the sensor on table but it accumulating some values. I am attaching some of my readings so you can check it out.
I am very glad if someone help me. accelerometer readings
The readings look rather precise to me. The fluctuations are in the hundredths of a m/s^2. And yes that might add up if you plan on calculating the speed or position of the device but you might add some noise filtering to cancel it out. Check here for a start:
Accelerometer Low Pass Filtering
I need to create an app that Calculates the moving car velocity/speed, with x/y/z speed.
My idea is using device's accelerometer.
I am using Sensor.TYPE_ACCELEROMETER and getting ax,ay,az (acceleration in x,y,z direction). how to get sped of device. Lots of physics formulas suggested by people to get speed but any one of then not giving correct speed compared to GPS. Please tell me code or good link which solve my problem.
That would be very difficult. To calculate the speed of the device, you need to calculate the integral of the acceleration. But to do so, you need to very accurately know for very dense points in time both the device's rotation and its acceleration. Assuming you do have those things, you simply need to take the device's initial speed, and for each point in time add to it (rotation matrix * acceleration vector * time to next measurement). That's probably the most accurate thing you can that is simple enough.
I am working in a monocular 3D Mapping project, and I need every time both position and rotation (angle).
To filter Gyroscope Data, I decided to use the "compass" and set 0 value to the angle if it's north.
But to get the position, I will need to double integrate the accelerometer value with a small sampling step (1ms) and 7 values mean filter.
I think this will make position more accurate. But does someone have an idea about the error range ? for example, in 10 meters, How much the error will be.
And does anyone have a better idea?
The sensors are from STM32F3 Discovery Board
Thanks
The STM32F3 has two sensors you'd be using:
LSM303DLHC accelerometer and magnetometer
L3GD20 3-axis digital gyroscope.
The sensor accuracy should appear somewhere in the datasheet. Since you'll be using several sensors, you'll have to calculate the total error over the time your measuring. Note, the error won't be a single number like 10 meters because it will accumulate over time. If you had a GPS or some other way of determining your position you'd be able to limit your accumulated error.
What you're doing sounds like an Inertial Measurement Unit. If you haven't already, I'd recommend reading up on that and also Dead Reckoning.
Please suggest some beginning point in this process of finding distance displaced by an iPhone. The requirement of accuracy in current system is in cm, and displacement can be in 3D.
What I have already done is
1. Tried using sound to calculated distance between between 2 iPhones, but I need distance calculation with one iPhone only, i.e need displacement.
2. Tried CMMotionManager and its accelerometer data, but values received is helpless.
I think I need a good filter to get useful data out of that junk. I already used Kalman Filter and gone through link
iphone accelerometer speed and distance,
How to calculate distance using accelerometer using iphone sdk?,
How do I measure the distance traveled by an iPhone using the accelerometer?,
Basic calculus behind this problem is in the expression
Tried DCT-II algorithm and Multidimensional DCTs to filter data.
I dont know what did I miss, or where should I go from here, as it is hard to believe that no one has used accelerometer for such an accuracy, because there are so many practical examples of it being used for greater accuracy.
Please provide me some pointer that suggest some way out of current situation.
You can't achieve cm accuracy. The reason is, surprisingly, the orientation error.
The above link contains some tips what you can do if you need displacement.
An even better alternative is to use orientation in you application, if you can.
What's the easiest way to plot location track based on series of reading of accelerometer/gyro/compass sensors taken over time? Let's say I have following data taken every second:
ElapsedTime(s) xMag(uT) yMag(uT) zMag(uT) xAccel(g) yAccel(g) zAccel(g) xRate(rad/sec) yRate(rad/sec) zRate(rad/sec) roll(rad) pitch(rad) yaw(rad)
...
Is there an easy way to draw a location plot for any given time? I'm using iPhone 4 with xSensor app to capture data, but can't just use GPS. I would appreciate any hints. Both standalone applications and Java libraries would be good.
Double integration of the acceleration vector (after gyro & compass direction correction) will give you a location from some initial or arbitrary offset. The problem is that any small offset or errors in the acceleration data, which there will be, will result in a rapidly diverging position.
What might be more possible is to get frequent and precise GPS position data, and use the acceleration data to estimate the route in between two very nearby GPS fixes.