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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Can we use neural networks to solve the problem of SLAM? and how?

As a neural network can estimate almost any arbitrary function, I was wondering if we can use it to replace traditional SLAM algorithm. If that is possible, please explain how exactly you think it can ...
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EKF slam Landmark covariance propagation

Is there an intuitive explanation for how loop closure reduces the landmarks of prior observations? In particular the landmarks are connected to each other only through the observer, observing a ...
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How to deal with inexact pointcloud matching?

When running ICP(for example with SLAM) it's possible your next position does not have a point cloud which matches up with the prior point cloud due to resolution limits. How is this dealt with it? ...
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Derivation of EKF slam landmark initialization

I have read a couple posts which gives the formula for initializing a new landmark in EKF slam but the derivation is not given. EKF-SLAM initialize new landmark in covariance matrix Could someone ...
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Incorporating motion model in Graph Slam and Bundle adjustment

When doing global bundle adjustment how does one incorporate a motion model or IMU information? Does it simply impose a cost function in relation to how far away the expected location is of the robot ...
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EKF slam vs global bundle adjustment

How does EKF slam and the covariance matrix interact with global bundle adjustment? In particular the covariance matrix gives you a confidence on location but global bundle adjustment does not. How do ...
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/rtabmap/rtabmap: Did not receive data since 5 seconds

trying to run RtabMap on my realsense-435 device. I've set up all the topics and made sure they are published and subscribed, nevertheless, RtabMap gives me this error: ...
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How to do path planning using only a fixed number of points?

I have a vehicle with cameras to detect different colored cones. I want to generate a drivable path based on the location of the detected cones.The number of detected cones varies, as it depends on ...
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Monocular SLAM position estimation

I have been reading about mono SLAM and I have a couple questions which are not so clear: When doing pose estimation, I have seen people both reference homography transformation and also reference 5\...
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slam_toolbox mapping is not life-long?

I've tested slam_toolbox producing life-long environment mapping, and not quite satisfied with the results. Below you can see a fragment of the mapping. I used a 1x0.5m case to test the changing map ...
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How to make gmapping dynamic, or advise any other methods to create mapping of a dynamic environment

it is a general question. Gmapping seems to be used only for creating a map of the static environment. Once created, it doesn't account for any changes - you add a new object, but it's being ignored ...
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How is loop closure mechanism incoporrated in particle filter based SLAM algorithm?

Could any one please explain, how is loop clousre mechanism introduced in filtering based SLAM techniques like FAST Slam ?
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Loop closure in 3d lidar slam

I am currently working on 3d LIDAR SLAM and trying to apply LOAM, LIO-SAM etc. I have already read some of these papers to get a better idea of the way they work. However, i did not find anything ...
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How to get from lidar coordinates to gps coordinates

I build a map from lidar slam lego-loam, which is a lidar odometer, and then I want to use this map by gps localization. I know the map will have errors in some ...
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How to calculate the covariance and gain in SLAM when only one measurement is available?

I am trying to perform SLAM for cases where only one sensor measurement is available. For example, suppose I want to track the position of a robot moving in a room with multiple known landmarks (2D ...
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Find a mistake in transformation between different coordinate frames in the WIP-calibration pipeline

I design the extrinsics calibration pipeline for the robotic agents, carrying onboard two sensors of different modalities. I aim to calibrate one of them (S) ...
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offset in gridmap

colleagues, i am currently viewing Cyrill Stachniss's course on SLAM and also doing the exercises. At the moment i am doing an exercise on occupancy grid mapping and there is some strange offset ...
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how can i drive the linear state space model of this ackerman steering model

i have an ackerman steering model like so : ...
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HECTOR SLAM, odometry in a low cost differential drive robot

I'm a noob in robotics trying to evaluate requirements for a low cost differential drive indoor robot. Would highly appreciate comments on the following questions. Given the inaccuracies in the wheel ...
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process has died , exit code -11

I installed this framework and followed the instructions, but when I run it, I get the following error: ros melodic ubuntu 18.04 ...
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How to compute the Hessian matrix in the robustified Gauss-Newton method for optimization

When robustifying the Gauss-Newton method used to find a local minima of a squared error function expressed by: $$f(\mathbf{x})=\frac{1}{2}\Delta\mathbf{z}(\mathbf{x})^T\Delta\mathbf{z}(\mathbf{x})$$, ...
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Using Google Cartographer library standalone

I am working on a project that requires the analysis of the results of different SLAM libraries with respect their accuracy on building a map. Right now, I am more interested in the development with ...
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Some doubts regarding SLAM and its technical terms

I have some questions regarding SLAM and some general technical terms used in the context of it. Q1) **Online SLAM vs Offline SLAM**. Can "Online" SLAM be also called "real-time" SLAM? What is the ...
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Calculate information matrix for graph slam

0 I am new to SLAM. I am working on graph slam where I need to do pose graph optimisation. For this requirement information matrix is required between two edges for which the transformation has ...
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How to calculate extrinsic calibration of a non-overlapping multicamera rig?

thanks for taking the time to check my question. Firstly, let me describe the current configuration, I am using 4 cameras that produce non-overlapping images and the goal is to calculate their ...
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Covariance of Gaussian after sequence of homogeneous transformations

Assume we have a robot that moves and observes landmarks on his path. The path is composed of $k$ poses $s_1 \: ... s_k$ where $s_i = [x,\ y,\ \theta]$. From the sensors, we read the motion ...
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Vulnerability of LiDAR systems for autonomous drones

I will soon be working on an autonomous drone project and we're planning to use LIDAR systems for localization & mapping. However, at the same time, we are looking into how to make drones safer ...
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difference between particle filter in slam and normal particle filter

I would like to ask you about what is the difference between particle filter when we use it in Slam methods and when we use it normally to correct our sensor measurement. I mean, is there any ...
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Cheap global shutter cameras with external synchronization

Please recommend cameras for multi-camera setup satisfying the following conditions: Relatively cheap (up to 100$ per camera). Global shutter. No filters on lenses or pixels. Resolution of 1 MP or ...
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Calculate transform from different poses

My robot is at a starting pose $s_0 = (x_0, y_0, \theta_0)$ and, while moving, I receive a sequence of motion measurements $[\mu_1, \mu_2, \: ... \: \mu_n]$, where $\mu_i = (\Delta x_i, \Delta y_i, \...
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Scale factor of Monocular SLAM (Simultaneous Localization and Mapping )

I am using ORB-SLAM3 with a monocular camera on a drone for Augmented Reality application. I need to know the absolute scale of the map formed by the SLAM. I cannot use a stereo or RBG-D setup. Tthe ...
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Relative scale problem

I am doing Monocular Visual Odometry, and I have problem with relative scale. Most of the time its value is between 0.8-1.1, but sometimes it goes crazy and it has value 3,4 and once it had value 25. ...
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Pose-Graph Optimization in MATLAB does not give expected results

I am trying to optimize a pose graph I created in MATLAB using either the optimizePoses(viewSet)-function on the imageViewSet that I have or the ...
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Frozen map + 'Message filter dropping' - Issues with mapping and navigation in ROS2 Foxy

sorry for the long post, just want to make sure i include all the details. I am working on learning ROS2 by building a robot which maps and navigates my apartment. I'm using the RPLidar A1 sensor ...
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What's the difference between factor graph optimization and bundle adjustment?

I see that in SLAM literatures, factor graph optimization is frequently used. While in Structure from Motion literatures, usually they use bundle adjustment. What's the difference between the two ...
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How to detect loop closures in 2D laser SLAM?

I am trying to build an occupancy grid map using odometry and 2D lidar data through graph optimization. I am not aware of any reliable loop closing methods using only the 2D laser scans. I have been ...
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Use 2 Cameras as 1 Stereo Camera

I have one Picamera and one normal USB Webcam and would like to use them together as one stereo camera. Is this even possible as the 2 cameras aren't exactly the same? I would like to use them in ROS ...
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Drone lost traj recovery

So I am using slam algorithm to localize the drone which is gps denied . The input to the slam algo is imu data and a video . Now after the first run of the slam algorithm it creates the trajectory ...
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How to calculate the ground truth of your own simple dataset for testing your SLAM Algorithm?

I have tested my SLAM algorithm on EuRoC, TUM and KITTI Datasets. But I would like to test on my own custom dataset. Moreover, I already rectify how to make my own dataset in TUM dataset format, but I ...
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No difference between UKF and EKF for SLAM

I built EKF and UKF SLAM algorithms. The problem is that I expected to see a difference because of the more precise approximation of the system in the UKF. Here's a screenshot from the estimated path ...
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Doubt regarding a slam parameter in research paper

I was reading about the SLAM problem in a research paper, Multi-robot Simultaneous Localization and Mapping using Particle Filters by Andrew Howard. What does '$m$' mean here? The SLAM problem for a ...
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SLAM - Angle calculation failure ?-EKF

i am currently building up a EKF SLAM. I dont know where my mistake is but i think it has something to do with the angle my robot is driving towards but im not completly sure. First i thought it could ...
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EKF Update Step measurement data doesnt fit state vector

I have an EKF SLAM Algorithm which tries to estimate the robots position (X,Y,Theta) + the X,Y coordinates of several landmarks. Like in the posted algorithm i have a range/bearing sensor. I ...
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What is the difference between a Bayes Net and a Factor Graph

I am just getting started on understanding Factor Graphs, by going through the excellent guide Factor Graph For Robot Perception by Dallaert and Kaess While I am familiar with the SLAM problem, and ...
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What is the Point of Monocular SLAM

I am not a V-SLAM expert yet, but as far as I understand with monocular V-SLAM there is a scale ambiguity introduced by the fact that a camera essentially is an azimuth sensor that maps the 3D world ...
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Is Lidar SLAM with only lidar sensor and no loop closure detection just a odometry?

I'm a newbee to SLAM. I have a question that in Lidar SLAM(including 2D lidar and 3D lidar), if I only use a single lidar without any other sensors like IMU and no loop closure in the mapping process, ...
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Sparcification of SLAM with SEIF (Sparse Extended Information Filter)

I am studying SLAM (Simultaneous Localization and Mapping) with textbook "probabilistic robotics". I cannot understand well about Sparsification step, so I found original paper for that; ...
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Compute how well a laser scan matches or overlaps with its environment given a map of the environment and location of the robot is known

If I knew the exact location of my robot and have an accurate map (for eg. an occupancy grid map) of the environment beforehand, how can I compute a measure of how well the laser scan data agree with ...
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EKF SLAM Prediction Step

My question relates to the prediction step in EKF SLAM when we get measurements. This is a question I've encountered while implementing EKF SLAM in ROS. At the beginning of the SLAM loop, we predict ...
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How can we calculate likelihood of sensor values wrt to actual real world?

I am trying to understand Bayes Filter. In its update step we have P(z_t|x_t) as observation model. Slide 37: Bullet 5 of this lecture states "Likelihood of ...
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