Questions tagged [slam]

SLAM (Simultaneous Localization And Mapping) refers to a robot building a map of its environment through it's sensor data (mapping) and keeping track of its own position in that map (localization) at the same time.

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How to use SLAM with simple sensors

What 2D SLAM implementations (preferably included in ROS) can be used with simple distance sensors like IR or ultrasonic rangefinders? I have a small mobile platform equipped with three forward ...
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1answer
194 views

EKF-SLAM: Shrink covariance matrix on one direction

I have implemented an EKF on a mobile robot (x,y,theta coordinates), but now I've a problem. When I detect a landmark, I would like to correct my estimate only on a defined direction. As an example, ...
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1answer
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Using SLAM to create 2D topography

I have a small mobile robot with a LidarLite laser range finder attached to a servo. As of now I have the range finder side-sweeping in a 30 degree arc, taking continuous distance readings to the side ...
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1answer
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Covariance and optimization

I am trying to build a map containing lamps as landmarks. I drive around with a robot and a monocular camera looking to the ceiling. The first step is detect the edges of each observed rectangular ...
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193 views

indoor positioning system: which is better? [closed]

Which method is better, in term of accuracy, for detection of indoor localization of a drone. Camera based system or wireless techniques like WLAN or Bluetooth?
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1answer
55 views

Orthogonal projection of laserscanner data

I recently discovered this ROS-package: http://wiki.ros.org/laser_ortho_projector . Which is basically exactly what I need. However I am not using ROS, so I need to do what is been done in this ...
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Real-time camera localisation in known environment

I am young researcher/developer coming from different (non-robotic) background and I did some research on camera localisation and I came to the point, where I can say that I am lost and I would need ...
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EKF-SLAM initialize new landmark in covariance matrix

I am trying to implement an EKF-SLAM using the algorithm for unknown correspondences proposed in the book "Probalistic Robotics" by Sebastian Thrun in Table 10.2 . By now I understand actually all ...
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2answers
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Is it possible to do SLAM with few IR sensors like Buddy?

I saw Buddy's page and want to purchase for my SLAM research. However, I wonder is it possible to program Buddy for SLAM? According to Buddy's spec, they're only few IR's, sonars and a camera. As I ...
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1answer
124 views

Optimal hardware for linear algebra operations

I've been working lately on SLAM algorithms implementing extended kalman filtering to brush up on some localisation techniques and I have been thinking forward to the hardware side of things. Are ...
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1answer
366 views

Need help regarding EKF in MonoSLAM

I am trying to understand the implementation of Extended Kalman Filter for SLAM using a single, agile RGB camera. The vector describing the camera pose is $$ \begin{pmatrix} r^W \\ q^W \\ V^W \\ \...
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3answers
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Hector SLAM, Matching algorithm

I'm trying to understand the scan-matching part of Hector SLAM (PPT summary). It seems a little difficult to understand, in some cases, how is it possible to actually perform the alignment of the ...
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1answer
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What is the difference between Positioning and Localization Systems

I would like to know what are the differences between Positioning and Localization Systems. In most review papers they are used interchangeably. Are they the same? For example: GPS(Global Positioning ...
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395 views

What is the difference between SAM and SLAM?

What is the difference between Smoothing and Mapping (SAM) and Simultaneous Localization and Mapping (SLAM)? These general approaches seem closely related. Can someone describe the differences?
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EKF over-correcting?

I've been implementing an extended kalman filter, following Thrun's Probabilistic Robotics implementation. I believe my correct step may be wrong, as the state appears to be corrected far too much. ...
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2answers
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using range-only sensors for mapping in SLAM

SLAM noob here but trying to implement an algorithm that fuses odometry data and mapping based on wifi signal strengths for a 2D robot. 1) After various readings of different resources, I came across ...
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962 views

EKF-SLAM Computing the jacobians for landmark updates

I've been working through this informative guide on EKF-SLAM but I'm having difficulty understanding the jacobians required for the 'landmark update', on page 35. What exactly is Jxr and Jz taking as ...
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1answer
656 views

EKF-SLAM, how best to manage the 'P' covariance matrix, programatically

I've recently been learning about SLAM and EKF-SLAM. I've began my implementation in python, but have had trouble managing the updating of P, especially when it comes to adding new landmarks. ...
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SLAM noob here, a few questions regarding EKF-SLAM

I've recently been learning about SLAM and have been attempting to implement EKF-SLAM in python. I've been using this great article as a guide. Some progress has been made, but I'm still confused by ...
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3answers
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RGB-D SLAM - Compute Information Matrix

currently im working on a RGB-D SLAM with a Kinect v1 Camera. In the front-end the SLAM estimates the pose with Ransac as an initial guess for the ICP. With the pose estimation i transform the ...
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1answer
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Graph optimization with G2O

I'm trying to do graph optimization with G2O, mainly in order to perform loop closure. However finding minimal working examples online is an issue (I've found this project, as well as this one. The ...
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1answer
121 views

Robotics SLAM datasets - scaling factor

There are several robotics datasets for SLAM, like this one. In this webpage you can see that the depth image is scaled by a factor of 5000, so that float depth images can be stored in 16 bit png ...
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3answers
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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_{\...
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808 views

GraphSLAM: why are constraints imposed twice in the information matrix?

I was watching Sebastian Thrun's video course on AI for robotics (freely available on udacity.com). In his final chapter on GraphSLAM, he illustrates how to setup the system of equations for the mean ...
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2answers
558 views

how to plot $\pm 3 \sigma$ of a landmark in EKF-SLAM

I have implemented 2D-SLAM using EKF. The map is based-feature in which there is only one landmark for the sake of simplicity. I've read some papers regarding this matter. They plot the $\pm3\sigma$ ...
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Single Touch Based Sensor and Odometry SLAM in Noisy Rectilinear Environment

A Co-worker said he remembered a 2011(ish) ICRA (ish) paper which used just a touch/bump sensor and odometry to do SLAM. I can't find it - I've paged thru the ICRA and IROS agendas and paper ...
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role of chi2 in SLAM back-end optimization

All-most all SLAM back-end implementation compute chi2 estimates. Chi2 computation is usually used to compute the best-fitness score of model to the data. How it is related to optimization framework ...
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4answers
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What is inverse depth (in odometry) and why would I use it?

Reading some papers about visual odometry, many use inverse depth. Is it only the mathematical inverse of the depth (meaning 1/d) or does it represent something else. And what are the advantages of ...
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1answer
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joint compatibility branch and bound (JCBB) data association implementation

I would like to implement the joint compatibility branch and bound technique in this link as a method to carry out data association. I've read the paper but still confused about this function $f_{H_{i}...
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SLAM Goal Babbling

I am struggling to find good links to the use of goal babbling in SLAM applications. Has this technique been used as a method for optimizing movement in a SLAM environment?
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Can mapping be done in real life applications without also solving the localization problem at the same time (i.e. SLAM)?

I know that Occupancy Grid Mapping requires the assumption that the robots' pose is always known when generating a map. However, I also know that in reality, position and orientation usually treated ...
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370 views

Is the accuracy of estimated position in localization better than estimated position in SLAM?

We estimate position of robot in localization and SLAM. My intuition says we get better position estimation in localisation than in SLAM because we have better sensor model likelihoods in localization ...
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What kind of lidar is necessary for SLAM?

I've read about various robots using a 2D lidar system for SLAM ( such as at IGCV, http://www.igvc.org/ ) but I'm wondering how good exactly does the sensor have to be? Specifically: What accuracy ...
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1answer
263 views

Scan Matching finds right rotation but false translation

I'm currently developing a SLAM software on a robot, and I tried the Scan Matching algorithm to solve the odometry problem. I read this article : Metric-Based Iterative Closest Point Scan Matching ...
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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 ...
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3answers
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SLAM without landmarks using sonar [duplicate]

I'm currently programming an app for a robot and I'd like to make him map a zone and then make him move autonomously from one point to another. I have to solve a SLAM problem, but the biggest matter ...
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2answers
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the uncertainty of initializing new landmark in EKF-SLAM

In EKF-SLAM (based-feature map) once the robot senses a new landmark, it is augmented to state vector. As a result, the size of the state vector and the covariance matrix are expanded. My question is ...
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1answer
116 views

Laser Beam based model probability in case of single particle

I am trying to calculate likelihood of laser scan($Z$) at give pose($x$) with known map ($m$) using beam based model $P\left(z_t|x_t,m \right)=\prod_{i=1}^{n}P'\left(z_i|x_t,m \right)$ My scan ...
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2answers
285 views

Ensemble Kalman Filter SLAM

I know that there is an extended kalman filter approach to simultaneous localization and mapping. I'm curious if there is a SLAM algorithm that exploits the ensemble kalman filter. A citation would ...
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2answers
496 views

Assumptions about the nature of landmarks in SLAM algorithms

I'm trying to understand the role of landmarks in SLAM algorithms. I've glanced over a few books concerning landmark based SLAM algorithms and I've come up with a rudimentary understanding which I ...
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3answers
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Is there any advantage to velocity motion models over odometry motion models for SLAM?

I've seen several examples of SLAM algorithms (EKF SLAM, Graph SLAM, SEIF SLAM) written in terms of the velocity motion model. I have yet to see an example of any SLAM algorithm utilizing the ...
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1answer
119 views

Finding changes in environment using 2d laser

I have known map of the environment (2d occupancy grid map). I am trying to find if anything changed in environment using 2d laser while navigating by using maximum likelihood of laser with known map. ...
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2answers
389 views

Comprehensive comparison of SLAM algorithms

I'm looking for a research paper or series of papers that compare the performance of various simultaneous localization and mapping algorithms for rovers in a variety of real world environments. In ...
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1answer
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EKF SLAM and Mahalanobis distance?

So far I have done EKF Localization (known and unknown correspondences) and EKF SLAM for only known correspondences that are stated in Probabilistic Robotics. Now I moved to EKF SLAM with unknown ...
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4answers
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Which micro-controler/processor to be used for autonomous stereo vision robot system?

I am very new two robotics, however I have a working stereo algorithm which I want to combine with a SLAM algorithm. I am developing this system for an other application but I decided integrating it ...
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1answer
145 views

sparse matrix in EKF SLAM

I've successfully done with EKF Localization Algorithm with known and unknown correspondences that are stated in "Probabilistic Robotics". The results make perfect sense,so I can estimate the position ...
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2answers
361 views

How can I achieve long distance, high quality 3D Scans on a mobile robot?

Am going to be competing in Robocup Rescue in Thailand next year - I was too busy to pull off a campaign for Brazil this year :( Will be using CUDA powered GPUs, Kinect/Xtions, and ROS as the primary ...
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1answer
306 views

SLAM without data association?

I would like to build 2D EKF-SLAM in openGL. I've implemented the entire virtual environment in which there is a robot that moves in 2D and there are some landmarks(feature-based map). I have the ...
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1answer
2k views

What is the best way to fuse measurements from IMU, LIDAR, and Encoder information in some recursive bayesian filter?

I am doing SLAM with a four wheeled (2-wheel drive) differential drive robot driving through some hall way. The hallway is not flat everywhere. And the robot turns by spinning in place, then traveling ...
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1answer
192 views

Slam and Vision (good resources)? [closed]

I would like to know if there is a good source that combines Slam problem with vision. From mathematical perspective, there are numerous resources that handle SLAM ,however, I didn't find a good ...

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