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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What does Simultaneous Localization And Mapping (SLAM) software do?

I took a course to have a better understanding of drones and their design. At the end of the course there was a test question that I got wrong and I would like to understand why. I was supposed to ...
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Dual constraint non-linear optimization for SLAM

I am trying to achieve a nonlinear optimization for SLAM on a function that contains two different constraints, like this : $$ T_{opt} = \underset{T}{\arg\min} \sum_i(\left\lVert T.X_i - x_i \right\...
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1answer
37 views

Good Software Projects for Aspiring Engineers [closed]

With the pandemic going on, our school has decided to officially shutdown all sponsored club meetings. Now that we are all digital, our robotics club was looking for projects that students can do at ...
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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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Intel Realsense Cameras for Object Avoidance and SLAM to go to destination

My goal is to make a UAV which can search an area while avoiding obstacles. I figured I would navigate using the SLAM and Intel Realsense D435i (a stereoscopic camera with an IMU built in), but all of ...
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Is SLAM done only first time in a given environment

I am training Turtlebot 2 to move around the office. I come from robotics hardware background but relatively new to computer vision and robotic mapping. Here are my two fundamental questions related ...
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3answers
286 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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2answers
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FastSlam 2.0 Implementation?

I have studied Claus Brenner's lectures on how to implement the FastSLAM 1.0 algorithm, where each particle maintains the robot pose, and maintains EKF's of the landmarks. However, I'd like to ...
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2answers
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Is pose estimation using images necessary in visual-inertial SLAM

In visual SLAM, pose estimation is performed between two adjacent frames or keyframes using feature detection and pose estitmation from corresponding features. However in visual-inertial SLAM, pose ...
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2answers
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What Software Is Used For Autonomy Software Simulation?

I don't have a physical robot but I would like to test the performance of my C++ code for odometry, SLAM, and path planning. Are there any good simulation software where I can test my algorithm ...
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1answer
31 views

How to derive the camera trajectory from ICP

This may be a very simple question so please bear with me... Suppose I have a stationary object and point clouds, $n$ $(x,y,z)$ points, of that object taken by a moving camera at time steps $t_i$, $...
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2answers
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Can standard SLAM techniques be used in maritime environments, where waves and currents move the vessel even with no control input

I am trying to implement a functioning SLAM system for an autonomous surface vessel (ASV). I don't have any direct experience with SLAM, and I am therefore researching the topic before I try to ...
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1answer
50 views

How does scan matching find overlapping regions in two scans?

I have been reading about scan matching and so far I have gathered that scan matching tries to find the transformation (rotation and translation) which leads to the best match between overlapping ...
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How to avoid matrix singularity in GraphSLAM

I am trying to implement GraphSLAM from Sebastian Thrun's paper, The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. When I compute the inverse of my information ...
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2answers
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What's the difference between Pose Measurement and Position Measurement?

I have read a robotic related paper called Estimating SE(3) elements using a dual quaternion based linear Kalman filter, and the author proposed that the equation of position measurement is denoted as:...
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How to obtain live vertical height values using LIDAR

I plan to control the flying height of my drone using a LIDAR (in real-time). Therefore, I would be attaching the LIDAR to my UAV, pointing vertically downwards. However, after looking at some of the ...
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1answer
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Feasibility of SLAM with heterogeneous sensors

Why are there so few published implementations of SLAM with support for heterogeneous sensors? Heterogeneous sensors include LIDAR, monocular cameras, stereo cameras, thermal sensors from more than ...
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Are there any Algorithms/Papers about 3D Mapping the Interior of Buildings using Computer Vision and IMU Data?

I was wondering if it would be possible to do something like this: Vision-based Autonomous Navigation and Mapping with a Small Quadrotor without using lidar/lasers. I have tried ORB-SLAM, but the ...
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2answers
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Variables that Improve SLAM

I have a general question regarding SLAM as I am not an expert on the topic. What are the variables that can improve map generation? The ones I can think of are: A higher resolution camera ...
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1answer
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Teaching AMCL and SLAM

In trying to explain these important concepts and algorithms it would be super useful to have a video or animation that illustrates through simulation the underlying math. All the videos and articles ...
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SLAM and navigation

I have a question about SLAM. Is it common for SLAM to be used for mere map generation? For instance, have a map generated using ORB-SLAM and then freeze the map for future path planning where future ...
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Fusion multiple LaserScans to PointCloud

I am currently trying to do 3D SLAM with two 2D Lidars and possibly additional IMU in ROS. However, there seems to be no ROS package available to meet my needs. The closest one would be laser_pipeline ...
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1answer
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Odometry heading and laser scan heading not point to same direction

please help, after so much research still cant find a single solution from google. some say offset, but there is no offset in the configuration. problem: odom direction and laser scan heading didnt ...
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1answer
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How to plot the 3D camera trajectory from a VSLAM output

I am totally new to VSLAM algorithms and would want to plot the path followed by the moving camera. I am using the open source implementation of ORB_SLAM2 for a rgb-d camera on benchmark dataset. The ...
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1answer
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Is it to possible to measure a room exact with rplidar?

I want to measure a room using rp3+, rplidar, ROS and SLAM. It should be easy possible to create mapping of the room. But how exact it would be? Is it possible to get less than 1 cm precision over ...
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1answer
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Depth images with undetectable outlines

I'm trying to capture depth images with a RGBD camera, but all of the images have undetectable outlines around objects: Is this expected from RGBD cameras or is mine a dud? It's an Astra Pro.
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TUM RGBD SLAM dataset file format inconsistency?

I'm looking at the TUM dataset and wonder why the depth images and the file formats appear to be inconsistent. According to the file formats: The depth images are scaled by a factor of 5000, i.e.,...
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What's the difference between the term “pose estimation” and “visual odometry”?

I'm reading a paper: Choi C, Trevor A J B, Christensen H I. RGB-D edge detection and edge-based registration[C]//Intelligent Robots and Systems (IROS), 2013 IEEE/RSJ International Conference on....
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1answer
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How to derive the Time-Update equation of SLAM

I was going through the tutorial on SLAM by Hugh Durrant-Whyte and Tim Bailey† and found this Time-Update equation (equation 4 in the paper): $ P\left(\mathrm{x}_{k},\mathrm{m} | \mathrm{Z}_{0:...
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1answer
142 views

Data structure to store a robot map

I'm studying robotics at the university and I have to implement on my own SLAM algorithm. To do it I will use ROS, Gazebo and C++. I have a doubt about what data structure I have to use to store the ...
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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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1answer
138 views

ORB-SLAM pose estimation

I've been reading about ORB-SLAM and ORB-SLAM2, but I can't quite figure out how pose estimation is done. I see that it uses a bag-of-word method for loop detection, but how are current features ...
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Relative quaternion to global with uncertainty

in this perfect tutorial i found how i can compose two poses with uncertainty and how i can transform one representation to another with uncertainty http://ingmec.ual.es/~jlblanco/papers/...
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1answer
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Camera pose to world coordinate transformation

I have managed to receive camera_pose for ORB-SLAM by following their code. If I run $ echo /world /camera_pose I receive something like this: ...
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1answer
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Error term formulation in Graph SLAM (conceptual doubt)

I am reading A Tutorial on Graph-Based SLAM.Grisetti, Kummerle, Stachniss & Burgard On page 5, the error function is introduced as follows $$e_{ij}(x_i, x_j) = z_{ij} - \hat{z}_{ij}(xi, xj)$$ ...
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2answers
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I have to implement my own SLAM algorithm [closed]

I'm studying robotics and one practice that I have to do is to implement my own SLAM system on ROS. I need some advice about where to start. Where do I start?
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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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In practical terms, how close is the accuracy of camera-based visual odometry/SLAM methods to lidar-based methods for autonomous car navigation?

Benedict Evans, a general partner at Andreessen Horowitz, claims that “almost all autonomy” projects are using lidar for SLAM, and that not all of them use HD maps. An MIT group is testing self-...
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How does a self-driving car locate itself when the environment changes?

There's something I don't quite understand about SLAM. When a self-driving car wants to locate itself using a prior map, how does it do that when the environment keeps changing, e.g., new cars parked ...
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1answer
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Lost on Graph slam's loop cloursure

What is the definition of loop closure in Graph Slam? Ref: Graph Slam The theory of Graph Slam define here but I think there is no hints about loop closure. I give this reference for review ...
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1answer
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SLAM from partly occluded LiDAR sensor

I am building my first project which will use 2D LIDAR for SLAM and the robotic platform is a small car. However the LIDAR is hidden inside and it's occluded by 4 cylinders which connect the roof with ...
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Any slam simulator without using ROS?

I found there are STDR and Stage simulators on ROS for SLAM and mobile robot simulation. But I’m trying to run simulations on my laptop that has really limited space, when I tried to install Stage, it ...
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1answer
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If you move the RGBD camera to other places on a Turtlebot, same orientation, create a map, does ROS navigation stack with AMCL still works?

I got a Turtlebot, and I’m thinking of putting the RGBd camera to other places. If you move RGBD camera to other places on a robot, same orientation, create a map, does ROS AMCL still works? I am ...
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What is the most appropriate SLAM algorithm for quadrotors with RGB-D camera?

I have been researching on SLAM. I came across EKF SLAM which uses odometry to measure the robot's initial position in the map and as well as landmarks which helps the robot's position to be more ...
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1answer
258 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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Sensor model and Inverse sensor model using occupancy grid mapping with lidar for particle filter

I'm a bit confused about how one goes about calculating the sensor model $p(z_t|x_t, m) $ and inverse sensor model for position $p(x_t |z_t,m_{t-1})$. From this answer, it seems like one way for ...
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1answer
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Help with Probabilistic Robotics Equation 13.22 detailed derivation

Equation 13.22 from Probabilistic Robotics below: Here's how I get from first line to second line: $$ p(x_{1:t}^{[k]} | z_{1:t},u_{1:t}, c_{1:t}) = \frac{p(x_{1:t}^{[k]}, z_{1:t},u_{1:t}c_{1:t}) }{ ...
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1answer
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SLAM Scan Matching. Scan vs previous-scan OR scan vs previous-map?

When using Scan Matching ICP for FastSLAM, which is the proper way to use it? Between the current scan and the previous one, or between the current scan and the stored map? Can both be used? If so, ...
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1answer
184 views

Likelihood Field Matching

I have LIDAR data of an environment in my hand and I want to apply likelihood field matching to this data. I found a source. But I don't understand what the variables of the algorithm mean and how it ...
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1answer
286 views

FastSlam2.0: ICP Scan Matching vs Odometry? What is the typical time step?

When working with a FastSlam2.0 algorithm, ICP Scan Matching is supposed to give more accurate measurements than odometry. The problem is, that given some noisy measurements from the laser scanner, ...

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