Questions tagged [localization]

Localization is the problem of estimating a robot's pose relative to a map of its environment.

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25
votes
5answers
24k views

Particle filters: How to do resampling?

I understand the basic principle of a particle filter and tried to implement one. However, I got hung up on the resampling part. Theoretically speaking, it is quite simple: From the old (and ...
23
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8answers
15k views

Absolute positioning without GPS

Using an IMU a robot can estimate its current position relative to its starting position, but this incurs error over time. GPS is especially useful for providing position information not biased by ...
19
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2answers
8k views

How To Determine Heading Without Compass

Lets say I drop a robot into a featureless environment and any magnetic field based sensors (magnetometer/compass) are not allowed. What methods are there of determining where north is? Tracking the ...
17
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3answers
4k views

What are good methods for tuning the process noise on Kalman filters?

Most often tuning the Kalman filter noise matrices is done by trial and error or domain knowledge. Are there more principled ways for tuning all the Kalman filter parameters?
17
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3answers
3k views

Quadcopter Localization Beacon

I want to use an RF beacon to localize my quadcopter for autolanding, when GPS is not precise enough, for example, when my driveway is only 10 feet wide, and the GPS is only showing 20-30 ft. accuracy ...
16
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2answers
2k views

EKF-SLAM Update step, Kalman Gain becomes singular

I'm using an EKF for SLAM and I'm having some problem with the update step. I'm getting a warning that K is singular, rcond evaluates to ...
14
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3answers
4k views

Extended Kalman Filter using odometry motion model

In the prediction step of EKF localization, linearization must be performed and (as mentioned in Probabilistic Robotics [THRUN,BURGARD,FOX] page 206) the Jacobian matrix when using velocity motion ...
12
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5answers
367 views

What's the most accurate way to obtain a locational fix using GPS?

Obviously GPS is the most obvious and accessible technology for obtaining a locational "fix" for a robot at any particular time. However, while it's great sometimes, in other locations and situations ...
11
votes
1answer
3k views

Ambiguous definition of Error-State (Indirect) Kalman Filter

I am confused by what precisely the term "Indirect Kalman Filter" or "Error-State Kalman Filter" means. The most plausible definition I found is in Maybeck's book [1]: As the name indicates, in ...
10
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4answers
3k views

What are human-friendly terms for mobile-robot orientation and relative direction of non-robot objects?

Within robotics programming, orientation is primarily given in terms of x, y, & z coordinates, from some central location. However x, y, z coordinates aren't convenient for rapid human ...
10
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3answers
2k views

With a 6-axis robot, given end-effector position and range of orientations, how to find optimal joint values

Given a six-axis articulated robot arm holding a tool at its end-effector, if I have a desired tool position and tool orientation, there will be exactly 1 solution to the inverse kinematics equation ...
10
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1answer
2k views

Why should I still use EKF instead of UKF?

The Unscented Kalman Filter is a variant of the Extended Kalman Filter which uses a different linearization relying on transforming a set of "Sigma Points" instead of first-order Taylor series ...
10
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4answers
6k views

How to make an “invisible line following robot”?

I would like to build a robot which follows a virtual path (Not a visible path like a 'black line on a white surface', etc). I'm just enthusiastic by seeing some sci-fi videos which show robots carry ...
9
votes
4answers
613 views

Localizing a swarm of robots

I have a 300cm x 300cm room with a 25cm high ceiling (yes twenty five centimeters). It contains 50 small wheeled robots (about 20cm x 20cm). A central computer will orchestrate the movements of the ...
9
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3answers
2k views

What algorithm can I use for constructing a map of an explored area using a number of ultrasound sensors?

Ultrasound sensors are incredibly cheap these days which makes them a popular choice for many hobbyist robotic applications, and I'd like to use a bunch of them (say 10) around a robot with an ...
9
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2answers
1k views

How to model unpredictable noise in Kalman Filter?

Background: I am implementing a simple Kalman Filter that estimates the heading direction of a robot. The robot is equipped with a compass and a gyroscope. My Understanding: I am thinking about ...
8
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4answers
2k views

In EKF-SLAM, why do we even need odometry when there is a more reliable sensor?Also, are all SLAM algorithms feature-based?

In the book of SLAM for dummies, why do we even need the odometry when the robot would use the data retrieved from the laser scanner which is more accurate than odometry? Why not just rerly on the ...
8
votes
2answers
11k views

Accelerometer, gyro, and magnetometer sensor fusion in 2d

I have not yet build this so this is basically a theoretical question. I am still wrestling with some C code to manage i2c communication etc. When I originally said "I have not build this" I meant ...
8
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1answer
1k views

Multiple position estimates fusion

I have a system in which I have two separate subsystems for estimating robot positions. First subsystem is composed of 3 cameras which are used for detecting markers the robot is carrying and which ...
8
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1answer
320 views

Understanding and implementing belief space planning

I am currently working on state estimation/navigation for a system with multiple robots. As of now, what I have is each robot localizing itself with a Kalman filter, given vision based measurements. ...
8
votes
1answer
274 views

innovation step ekf localization?

Let's say we have a bunch of observations $z^{i}$ from sensor and we have a map in which we can get the predicted measurements $\hat{z}^{i}$ for landmarks. In EKF localization in correction step, ...
8
votes
1answer
445 views

Monte-Carlo Localization

I'm implementing Monte-Carlo localization for my robot that is given a map of the enviroment and its starting location and orientation. Mine approach is as follows: Uniformly create 500 particles ...
8
votes
1answer
197 views

What kind of performance can I expect when using an Extended Kalman Filter for calibration and localization?

Currently I have a tricycle style robot that uses an extended kalman filter in order to track 6 state variables. The inputs to the system are a steer encoder, a distance encoder, and a rotating laser ...
7
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4answers
989 views

How to localise a underwater robot?

I am building an autonomous underwater robot. It will be used in swimming pools. It should be capable of running in any normal sized pool, not just the pool in which I test. So I cannot rely on a ...
7
votes
2answers
1k views

Whats the logic to implement a particle filter for a robot with range sensor?

I am trying to implement a particle filter for a robot in Java. This robot is having a range sensor. The world has 6 obstacles - 3 in the top and 3 in bottom. I am calculating the distance of the ...
7
votes
3answers
985 views

Visual Odometry options? [closed]

What are the pros/cons of the different visual odometry options? Stereo Camera Optical Flow SLAM other? Criteria: how well it performs vs other odometry options/sensors (lidar, radar) sensor ...
7
votes
1answer
218 views

Can you seed a Kalman filter with a particle filter?

Is there a way of initializing a Kalman filter using a population of particles that belong to the same "cluster"? How can you determine a good estimate for the mean value (compute weighted average ?) ...
7
votes
4answers
4k views

Robot docking for self-recharging

I want to build a simple obstacle avoider robot, but this time I want it to be self-recharging so I am building a dock for this purpose, so I want it to be able to locate the dock and go for it when ...
6
votes
1answer
4k views

Build a ROS robot with SLAM without laser

I've build a simple wheeled robot based on two continuous servos, controlled by Raspberry Pi running ROS-groovy, with a smart phone mounted on top to provide additional sensors. I'd like to situate ...
6
votes
3answers
1k views

Motion Model for Holonomic Robot

We are working with an holonomic robot equipped with three (120 degree shifted) omnidirectional wheels. The relative movement is estimated by dead reckoning using wheel encoders. To improve this ...
5
votes
1answer
281 views

laser scanner distance

I'm looking at laser scanners and I see a huge range of detection distances. The furthest I've see are 30m if you exclude the very expensive ones that claim up to 150m. My question is what is the ...
5
votes
2answers
1k 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 ...
5
votes
4answers
591 views

Do simple, non-sonic, omni-directional rangefinding beacons exist?

I am on a robotics team that plans to compete in a competition where one of the rules is that no sort of sonic sensor is allowed to be used. I guess that limits it to some sort of EM frequency right? ...
5
votes
2answers
7k views

Kalman Filter GPS + IMU

I know this probably has been asked a thousand times but I'm trying to integrate a GPS + Imu (which has a gyro, acc, and magnetometer) with an Extended kalman filter to get a better localization in my ...
5
votes
2answers
291 views

Different Particle Filter min and max particle numbers give almost the same result

I'm using amcl package in ROS to localize a mobile robot. I've changed min_particles and max_particles several times then ...
5
votes
1answer
3k views

Kalman filter GPS + IMU fusion get accurate velocity with low cost sensors

I'm new to all this robotics stuff. Especially to Kalman filter. My initial goal is to have velocity as accurate as possible Here is my case: I have a phone which is mounted, for example in the ...
5
votes
2answers
414 views

SLAM for Autonomous car

I am working on SLAM for autonomous car like vehicles with 2D lasers and IMU (deriving odometry). I would like to know how efficient is using the existing SLAM algorithms (for example: gmapping in ...
5
votes
1answer
918 views

LIDAR Points as Landmarks

I am currently trying to implement a GraphSLAM/SAM algorithm for LIDAR. From papers I've read, you generate a directed graph from expected LIDAR measurements to landmarks similar to the image below (...
5
votes
1answer
109 views

What frame of reference is used during Visual Servoing?

I'm new to the whole visual servoing area. I'm now reading the tutorial Visual Servo Control Part I: Basic Approaches" and I don't understand something fundamental - what information is available to ...
4
votes
3answers
5k views

Determining position from a 2D map and LIDAR

We need to determine the 2D position of my robot. To do so, we have a LIDAR at a known high, with an horizontal plane, which gives us the distance to the nearest point for each angular degree (so 360 ...
4
votes
3answers
871 views

Algebraic and geometric in inverse kinematic

I'm just wondering that is there any case that when algebraic way can't solve the problem while the geometric can ? Cause I'm working on a 2DOF robotics arm This one, I know the length of L1 and L2, ...
4
votes
3answers
2k views

Plotting location using wheel encoder data

Context: I am working with the SFU Mountain Dataset [http://autonomylab.org/sfu-mountain-dataset/] The UGV image - via the SFU Mountain Dataset website: I have used the following state update ...
4
votes
3answers
470 views

Addressing the sample impoverishment in particle filter

I have implemented a particle filter algorithm for the state estimation of a mobile robot. There are several external range sensors(transmitters) in the environment which gives information on the ...
4
votes
2answers
693 views

How can my robot find its position in any given map without GPS, including when the initial point is not given?

Consider this map The Contest arena shown in figure 1 consists of two sub arenas, both the sides are identical to each other and their scientists and safe zone locations are similar. Each sub arena ...
4
votes
1answer
2k views

Particle filter implementation in ROS

I'm looking for particle filter implementation in ROS to use in mobile robot localization, but it seems the only available package is amcl (Adaptive Monte Carlo), I'm not sure is it possible to use it ...
4
votes
1answer
205 views

Local Localisation with particle filter

I am doing Local Localisation with sonar, particle filter (i.e all particles are initially with robot pose). I have grip map of environment. When I execute algorithm in environment (where doors are ...
4
votes
3answers
1k views

question about car-like robot localization based on dead-reckoning

I have a question about car-like robot localization using only dead-reckoning. Given: robot position (at current time step) in the form $\begin{bmatrix}x & y & \theta\end{bmatrix}$ (theta is ...
4
votes
1answer
676 views

Are there off the shelf solutions for GPS+INS (accelerometer,gyro,magneto) sensor fusion for getting filtered/fused location and speed output?

I am working on a project that needs tracking location and speed of pedestrians/runners/athletes (so not really robotics, but I see a lot of related usage and posts in the robotics domain, and an ...
4
votes
2answers
2k views

Navigating through a Maze using path-planning (Dijkstra)

I'm working on an robot that would be able to navigate through a maze, avoid obstacles and identify some of the objects in it. I have a monochromatic bitmap of the maze, that is supposed to be used in ...
4
votes
2answers
779 views

Structuring EKF to estimate pose and velocity with odometry inputs

I have a differential drive robot for which I'm building an EKF localization system. I would like to be able to estimate the state of the robot $\left[ x, y, \theta, v, \omega \right]$ where $x, y, \...

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