Questions tagged [noise]

Unwanted or modified signals detracting from some form of reception or perception.

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16
votes
2answers
4k views

covariance matrix in EKF?

I'm struggling with the concept of covariance matrix. $$ \Sigma = \begin{bmatrix} \sigma_{xx} & \sigma_{xy} & \sigma_{x \theta} \\ \sigma_{yx} & \sigma_{yy} & \sigma_{y \theta} \\ \...
12
votes
3answers
944 views

What determines the amount of noise an actuator produces?

Many robots and other mechanical devices produce the signature whirring noise as they move, some produce less. What makes the difference? What restrictions a silence requirement places on a robot?
10
votes
2answers
258 views

How to model the noise in a range sensor's return?

Range sensors (for example sonar, infrared, and lidar) are notoriously noisy. How can I characterize the noise characteristics to include these in a probabilistic localization sensor model?
8
votes
1answer
8k views

How are units of noise measurement related to units of a sensor's data measurement?

I'm trying to understand how noise is represented for accelerometers, gyroscopes, and magnetometers so that I can match the requirements of my project with the standard specs of these sensors. I ...
6
votes
2answers
2k views

What is a good approach for outlier rejection during real time data filtering?

I'm trying to finish up a localization pipeline, and the last module I need is a filtering framework for my pose estimates. While a Kalman filter is probably the most popular option, I'm using cameras ...
6
votes
2answers
382 views

Kalman Filter and the state noise vector?

I'm reading Probabilistic Robotics by Thrun. In the Kalman filter section, they state that $$ x_{t} =A_{t}x_{t-1} + B_{t}u_{t} + \epsilon_{t} $$ where $\epsilon_{t}$ is the state noise vector. And ...
6
votes
1answer
481 views

How do you determine EKF process noise for pre-recorded data sets?

I've seen this question, which asks about determining the process noise for an EKF. I don't see anything there about pre-recorded data sets. My thought on how to determine the noise parameters, ...
5
votes
1answer
1k views

Noisy magnetometer data

I’m looking to develop an AHRS for which I’m using a magnetometer to correct for heading errors. I wanted to check that the magnetometer I'm using is functioning to the level of accuracy (+- 1 degree) ...
5
votes
1answer
756 views

How to choose the state space model for 1 axis gyroscope to implemnt a good kalman filter

I am using this gyroscope in order to measure the rotation of my robot around the z axis. I want to implement a kalman filter in order to improve the values. What i came with since now is this space ...
4
votes
1answer
1k views

Velocity Model Motion in Matlab (Probabilistic Robotics)

I want to implement the velocity motion model in Matlab. According to Probabilistic Robotics page 124, the model is as following \begin{align*} \hat{v} &= v + sample(\alpha_{1} v^{2} + \...
4
votes
1answer
908 views

Filtering IMU angle discontinuities

I try to measure Euler angles from an IMU, but some discontinuities happens during measurement, even in vibrationless environment, as shown in the images below. Can someone explain which type of ...
4
votes
1answer
195 views

Why doesn't this kalmanfilter filter anything? Reduce disturbances and noises with LQG controller

I have a state space model which look like this: $$ \ \begin{bmatrix} \dot{x} \\ \\\dot{\tilde{x}} \end{bmatrix} =\begin{bmatrix} A - BL& BL \\ 0 & A-KC \end{bmatrix} \begin{bmatrix} x\\ \...
4
votes
2answers
625 views

IMU based acceleration parameters for differential drive robot

I have a differential drive robot whose motors are virtually quiet while driving on a completely flat surface, but the motors make a lot of noise when on a incline. This is likely due to the ...
4
votes
2answers
159 views

KF/ EKF - Modelling and tuning noise matrices and other parameters

I am developing C++ code to estimate roll and pitch of a camera using accelerometer and gyroscope. The roll, pitch and yaw are in my state space ($X_t$) and the process is modeled as: $\bar{X_t} = X_{...
3
votes
2answers
648 views

Can I write the seperation principle for LQG controllers in this state space form?

Look at this picture. This is the seperation principle diagram. It is an LQG controller which going to control the real life process. What I want to do, is to create a state space model for this ...
3
votes
1answer
418 views

Wheel odometry simulation using ground truth

I'm tracking the state of a robot $X=(x,y,\theta)$ where $x$ and $y$ are the ground coordinates and $\theta$ the heading angle. I have the ground truth states $X_{gt}=(x_{gt},y_{gt},\theta_{gt})$. I ...
3
votes
2answers
361 views

Odometry motion model for Kalman filter, but is the error zero mean?

I was planning on using the odometry model in the prediction stage of an Extended Kalman Filter. State transition equations: $$ f(X_t,a_t) = \begin{bmatrix} x_{t+1} = x_t + \frac{\delta s_r + \delta ...
2
votes
2answers
144 views

Practicality of using magnetometer inside AUV

I have an AUV with a 12 inch diameter, 29 inch long capsule. Inside the capsule sits an Intel NUC computer, an NVIDIA Jetson GPU, an Arduino Mega, a Sparton IMU (9 DOF) as well as a custom voltage ...
2
votes
1answer
127 views

Can motion model noise be zero?

Can I assume the noise of motion model to be zero? If so, what are the consequences of doing so?
2
votes
3answers
119 views

The uncertainty is big while the sensor is rather accurate at measuring a landmark in EKF-SLAM

I've a 2D sensor which provides a range $r$ and a bearing $\phi$ to a landmark. In my 2D EKF-SLAM simulation, the sensor has the following specifications $$ \sigma_{r} = 0.01 \text{m} \ \ ,\sigma_{\...
2
votes
2answers
616 views

ArduIMU noisy output in Quadrotor

We are using ArduIMU (V3) as our Quadrotor's inertial measurement unit. (we have a separate board to control all motors, not with ArduIMU itself). Now we have a problem with ArduIMU's sensors output....
2
votes
1answer
197 views

Why does one IMU axis influence another?

For a home robotics project I just bought a BerryIMU to connect it to my Raspberry Pi. After hooking it up I ran the provided Python code to read out some values while moving it around. If I keep the ...
1
vote
1answer
188 views

What Does the Sensitivity Function Mean?

I'm studying for a test in Automatic Control and I have some troubles understanding sensitivity functions and complementary sensitivity functions. There's one assignment from an old exam that sais "...
1
vote
1answer
38 views

What is the noise in this PWM signal?

I'm in the process of calibrating servos while constructing a new hobbyist robot arm. When testing the base rotation servo I noticed some unexpected noise in the PWM signal while the servo is in ...
1
vote
1answer
69 views

Kalman filter: 3D measurement error to individiual components

I'm working on a Kalman filter for estimating the position of a point in 3D space. I know that I can measure its 3D position directly with a variance of about 2 mm (in other words: the variance of the ...
1
vote
0answers
50 views

Heading drift on Beaglebone Blue on small AUV due to power cables (I think)

At my work we use the BeagleBone Blue boards to control somewhat small AUVs. The board is placed in underwater tubes along with batteries, ESCs for thrusters and all other electronics. We use the in-...
0
votes
1answer
68 views

EKF singularity problem when measurement noise R is zero

my Extended kalman filter (EKF) program works well, my estimated state vector is same as real state vector when I give any positive definite number to measurement noise R. But I want to make ...
0
votes
1answer
32 views

Understanding import attributes of electronics speakers, by example

I'm new to electronics/robotics and I'd like to start with a simple project that uses a speaker to play sound clips when a certain event/input/stimulus is detected. Looking on Digi-Key and similar ...
0
votes
1answer
263 views

Should the kalmanfilter have disturbance as input?

This is a kalmanfilter As you can see, the process noise(disturbance) is not going to the kalmanfilter. But the state space model for the state feedback system is written as this: https://youtu.be/...
0
votes
2answers
693 views

Eliminating Electrical Noise from my motor driver

Background: I am using an Arduino Mega connected to a RoboClaw 2x60A motor driver. I asked this question about the system, but I have since narrowed the scope of the problem. I tried adding a bunch ...
0
votes
1answer
24 views

What would be a way to estimate IMU noise covariance matrix?

Weirdly enough, my robot platform which has an official ROS package supported by a manufacturer doesn't provide any covariance matrices of its sensors. So, I'm basically trying to estimate these ...
0
votes
1answer
43 views

Eliminating drift generated from double integration of acceleration signal using Envelope Method

I'm trying to remove the drift generated upon the double integration of a noisy acceleration signal. But this question discusses only removing the drift upon single integration to generate velocity ...
0
votes
1answer
66 views

Simulating sensor readings based on an existing Alan Variance Analysis

My goal is to model an accelerometer and a gyroscope based on real hardware. I understand deterministic errors like bias and scaling but the different types of non-deterministic errors are difficult. ...