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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Why does the low variance resampling algorithm for particle filters work?

I am studying and coding particle filters and I am using the Low variance sampling algorithm suggested in the Probabilistic Robotics book. I understand the procedure for the algorithm. A random number ...
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79 views

How to generate Particles in Particle Filter?

I have been trying to implement FastSlam 1.0. To implement this, I need to create particles. Now my confusion is how to create Particles? I have some odometry and Measurement data. Using those data ...
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Graph slam augmentation of Identity Matrix

I am trying to implement GraphSlam. I go through this paper http://robots.stanford.edu/papers/thrun.graphslam.pdf. I have some doubt about the algorithm. I attached a picture with this question My ...
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Matrix is singular error in GraphSLAM

I have gone through The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. I implemented the code for GraphSLAM. The fundamental formula of GraphSLAM is $$\mu = \Omega^...
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124 views

GraphSLAM data accumulation problem

I try to implement GraphSLAM from this tutorial, The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. I have some doubt while studying this paper. I hope people who ...
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1answer
53 views

GraphSlam Matrix Subtraction doubt

I am trying to implement GraphSlam from this paper. I have some doubt regarding the algorithm described in this paper at table2: Algorithm GraphSLAM_linearize. I have a doubt in line 7. As per my ...
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63 views

GraphSlam doubt about variable elimination technique

I am trying to implement Graph Slam. For tutorial purpose I read the paper "The GraphSlam Algorithm with Application to Large-Scale Mapping of Urban Structures" by Sebastian Thrun. At the beginning of ...
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How to update a new pose in iterative pose optimization problem?

There are multiple ways to update new pose in iterative pose optimization problem. The easiest one we often find in papers in robotics is as SO3 + translation Update on right \begin{equation} \...
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583 views

ROS: joint_state_publisher dies when used in remote launch file

I've been trying to run robot_state_publisher and joint_state_publisher on a remote TX1 running Ubuntu 16.04 and ROS Kinetic. When running the node from a local launch file (manually ssh into the ...
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Any reference for “3D feature matching + ICP”?

One of the simple tricks in getting high performance for a global 3D point cloud registration is combining "3D feature matching + ICP". For example FPFH matching + RANSAC for initial pose estimation ...
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How can I get the distance from a robot to a beacon?

I'm planning to create a Raspberry Pi robot to map a room. I intend to use a particle filtering algorithm as one of the central points of the project, that will allow me to work out my position ...
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Confusion of EKF equations

I read Probabilistic Robotics by Sebastian THRUN (online version). I also read http://ais.informatik.uni-freiburg.de/teaching/ws12/mapping/pdf/slam04-ekf-slam.pdf Question1 : What will be the ...
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EKF based Slam implementation with landmark identification in Global frame

I am working on mobile Robotics. I want to implement Slam. I have a very specific question about EKF Slam. To implement Slam I read the book "Probabilistic Robotics". I read its online version. There ...
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2answers
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Why use GraphSLAM?

I am doing some project on Slam. I have a data set of a moving Robot which can give me the value of forward velocity(m/s) and angular velocity(rad/s) and time(s). Now if this data are provided I can ...
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332 views

How does marginalization of variables effect least squares SLAM energy function?

Consider a simple example of Bundle Adjustment where I have robot and landmark poses $x = \left[ x_p \text{ } x_m\right]^T$ and measurements given by $z$, such that a simple factor graph can be ...
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Which is a good and cheap 3D LIDAR or other options? [closed]

Our team is planning to go for European Rover Challenge (ERC) 2018 for which we are designing an Autonomous rover. In order to implement SLAM, we need a way of mapping (with a range of atleast 2-4 ...
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166 views

Does marginalization increase the number of edges in Graph SLAM?

I thought marginalization does not change the number of the edges but this material (page 11) describes that as a result of marginalization we will have more edges in graph. Why does it increase the ...
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How to penalize blurred images in Bundle Adjustment?

We know that when rotational and linear velocity of the camera is high it is highly likely to get blurred images. The blurred image affects the quality of the accuracy in the feature tracking problem. ...
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Why do we need a marginalization in Bundle Adjustment?

A common practice in Bundle Adjustment is to reduce the state dimension by marginalizing structure or pose states to improve the optimization speed. In case 3d points(structure) $\textbf{p}_i$ are ...
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207 views

Scale estimation in datasets for monocular odometry

Suppose I've developed a monocular SLAM or odometry algorithm. Then I want to test it on some dataset, for example KITTI, TUM etc. How should I deal with the absolute scale in this way? Thanks.
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3D mapping using only a 2D Lidar

How can I map a 3D environment using only a 2D lidar? The lidar would be hand held and it would have 6 DoF. So if I move it in arbitrary motion in all 6DoF, I expect my algorithm to generate a 3D map ...
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1answer
326 views

Camera ego-motion estimation via dense optical flow

Help me please resolve some questions in the article 1) "A Robust Method for Computing Vehicle Ego-motion", Gideon P. Stein et al. According to this paper we can find three components of motion (...
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What is appearance-based SLAM?

To my understanding appearance-based SLAM uses only information coming from sensors for mapping and localization. It completely discards control information from actuators. I'm I correct?
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240 views

Methods for odometry/IMU/Gyro free lidar pointcloud registration for pose estimation

I am currently trying to register a pointcloud in time to find my change in position and heading at each timestep (High speed application). So this is essentially an implementation of SLAM. I am ...
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3answers
298 views

loop closure detection in visual SLAM

A robotic system is moving a getting its current location using visual odometry (incremental estimation of rotation and translation). To correct its localization, a loop closure technique may be added....
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Monocular SLAM depth reconstruction

I am trying to derive the inverse depth equation used in monocular SLAM algorithms. Specifically the equation 8 of the ORB SLAM paper I am very close, except I do not understand where the (u_j-c) ...
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1answer
387 views

Questions about SLAM: bundle adjustment, covariance etc

I have been recently studying about the SLAM family of algorithms, with the idea of implementing some for a multi-robot framework I have. With regards to the concept, I have a couple of related ...
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Camera calibration sequence with ground truth data

I'm looking for a SLAM dataset (monocular or stereo) specifically with a checkerboard, meaning the camera always has a checkerboard in frame. Most popular datasets provide calibration sequences, ...
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Calculating the covariance matrix of a measurement

I want to estimate the covariance matrix of a measurement for a robot evolving on plane and having the following state vector. $$ X = \begin{bmatrix} x\\ y\\ \theta \end{bmatrix} $$ $x$ and $y$ are ...
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In the SLAM for dummies what is z-h in updating X?

In SLAM for Dummies there is on page 40 this formula: $X = X+K(z-h)$ What is $z-h$ in updating $X$?
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350 views

How can we estimate the likelihood field for a particular scan in probabilistic terms?

I am trying to implement a scan matcher using Scan based sensor model but I cant figure out how to estimate likelihood for a particular scan. Is there any implementation available ? Would be thankful ...
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2answers
916 views

ROS + SLAM + kinect. which platform to use?

I am doing a project where I've robot which will be using kinect + ROS for Simultaneous Localization and Mapping. Which board should I use? I've heard that Raspberry pi , beaglebone are not sufficient....
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1answer
787 views

Marginalization in Graph SLAM [duplicate]

I have several questions about the process of marginalization in SLAM algorithms: 0 - What are the mathematic intuition behind marginalization process 1 - I know marginalization of states or points ...
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165 views

EKF based SLAM, marginalization and key-frames

I have a couple of tightly related questions regarding EKF-based visual SLAM. It is common in the Kalman based VSLAM litterature to marginalize 3d points and past poses. Condsidering the EKF as a ...
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689 views

How would i implement position and heading readings into my SLAM system?

I am trying to build a low-cost SLAM system with an MPU-6050 and GY-271 (magnetometer). Currently, i have a robot with an Arduino that collects the sensor data and a Raspberry Pi that (hopefully) will ...
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1answer
95 views

Do i really need an AHRS for 2D maps?

I am currently making a 2 wheeled SLAM robot that will use an array of either ultrasonic or sharp IR sensors with a particle filter. I also have a MPU-6050 and GY-271 and i am looking to turn it into ...
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138 views

Kalman filter localisation equations

I am doing mobile robot localisation as a project. Now I stuck in obtaining the equations of EKF localisation. My robot moves straight for 10 seconds parallel to x-axis and robot equipped with 2 ...
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1answer
20 views

Can we specify the working zone for the robot using SLAM approach for navigation?

I am using SLAM for the autonomous vehicle navigation. I want to the specify the working zone for the vehicle before the start of navigation, or can we restrict the working zone of the vehicle using ...
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3answers
285 views

Grid based SLAM using BeagleBone Green Wireless and RPLIDAR

I've written a grid based DFS algorithm with a PID-based steering system to maneuver a 30cm2 square-grid maze all in Python. The robot is a 4 wheel drive with an approximate size of 20 cm. The ...
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1answer
343 views

Why the IMU measurements only accumulate drift in 4DOF

I'm studying the Technical Report of VINS-Mono: A Robust and Versatile Monocular Visual-Inertial State Estimator available at: https://github.com/HKUST-Aerial-Robotics/VINS-Mono/blob/master/...
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1answer
267 views

What is the intuitive explanation of using Jacobian of observation model while calculating Kalman gain in EKF SLAM?

The idea of using Kalman gain in EKF SLAM is to figure out how much we trust our motion model and sensor/observation model. As explained in The Extended Kalman Filter: An Interactive Tutorial for Non-...
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1answer
125 views

Why EKF-SLAM uses EKF instead of linear Kalman Filter?

I am writing a bachelor's diploma on vSLAM. I learned and programmed EKF-SLAM like it's written in MonoSLAM paper, and I was going to write, that I can't use KF and have to use EKF because of non-...
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1answer
366 views

Pose-graph-slam:using only a camera

I'd like to know how to form my pose graph if the only information I have available is that from a camera, (1) What are my poses? Are they just the accumulated transformations from pairwise matching? ...
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1answer
490 views

Regarding Pose Graph Slam using Lidar

So I'm trying to incorporate pose graph optimization into a mapping framework using a Lidar. So I basically have all the relative transformations between the pointclouds and I have pairs of ...
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1answer
446 views

How to implement RANSAC and kalman filter or particle filter algorithms with ROS packages?

I'd like to implement those algorithms by using ROS packages to solve one way the SLAM problem. I know that gmapping, Rviz, slam_gmapping and robot_pose_ekf (for extended kalman filter) could be ...
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3answers
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Which sensors will best suited for indoor/outdoor SLAM system with high accuracy of localization? [closed]

We need a SLAM system for mobile platform which will be used in on-site construction. We are to build a 3D map from clouds of points and need localization in it. We don’t need fast localization, but ...
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2answers
362 views

Can i use a predictive kalman filter to 'increase' my sample rate?

I have a slam algorithm that outputs at around 30Hz, an implementation of ORBSLAM2. https://github.com/raulmur/ORB_SLAM2 I am reading this into a renderer that expects 60+ Hz. Because my sample ...
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3answers
3k views

A sensor that can see glass/transparent objects and surfaces

I am currently thinking about making a robot that will autonomously drive around the place. The place I want this robot to drive in however contains quite a few glass walls. When mapping the area I ...
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195 views

Scaling monocular SLAM with another source?

I have implemented a stable monocular slam tracking system, based on ORBSLAM2. I am trying to find a way to add real-world distance/scale to this. At the same time, I am running a (less stable) ...
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3answers
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How to call remote ROS node on mobile robot through laptop using wifi?

I've recently tried to get the remote ROS node on a mobile robot through wifi. This is as below picture. I've run roscore command on both laptop and mobile robot ...

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