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 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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what is ultrasonic based slam

i am confused about SLAM implementation, and i need your advise to organize my mind. Fist let me say that i have to generate 2D map, what is in this case the SLAM input? is it like (x1,y1),(x2,y2)...(...
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Ground Truth Visual SLAM Data Set

Can you please point me to a data set that can be used to validate monocular visual SLAM? My vision for what this data set looks like is a series of frames, with ground truth pose, ground truth pixel ...
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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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71 views

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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245 views

Plot a map using wheel encoder and IMU data

I want to plot a map( with matplotlib or any other library ) using a wheel encoder and IMU data. Eg:- For every 10cm robot moves it should draw line (in a graph) and draw angles depending on the data ...
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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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38 views

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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157 views

Estimate noise covariance matrix of measurements using a ros-bag

I am facing the following issue, and some hint or orientation would be great. I am working on a project in which I was given a ROS bag, and I have to implement a localization node using SLAM. To do so,...
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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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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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How do you handle angle discontinuities in estimation problems?

When one is implementing a state estimator in a system that involves kinematics, will inevitably face the problem of angle discontinuities, i.e., the fact that the angles have to be wrapped between ...
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Localize a Mobile Robot on a Mirror

I am currently busy with a project which requires me to construct a robot capable of cleaning a heliostat (movable mirror used to redirect sunlight). Heliostats are basically large flat mirrors that ...
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72 views

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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Make robot drive as far from obstacles as possible

I am trying to make robot drive around the room, avoiding obstacles with pathfinding. The problem is I get few waypoints from pathfinding algorithm for robot to drive to (green dots), but it drive a ...
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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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338 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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Effect of platform speed (how fast it is moving) on the quality of SLAM

I want to know how big of on an impact does the speed of the platform on which your sensors are mounted have on the quality of the outcome of a SLAM solution. Are there are any methods that are better ...
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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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EKF SLAM : Missing older landmarks in new observation

I am a beginner to SLAM and robotics in general and I have been trying to implement SLAM on my GoPiGo3 robot car kit using primarily Chapter 10 from Probabilistic Robotics by Sebastian Thrun as ...
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243 views

Position Estimates from sensor fusion

I have a quadcopter, and several components in play. First, I have a real position system (VICON), and I also have a SLAM platform. Then, of course, the IMU on the quadcoptor. I am trying to ...
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28 views

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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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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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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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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What's the correct approach to merging of localization and odometry data?

We've got a mobile platform with a source of odometry and an IMU, which are merged in an EKF filter (robot_localization node), producing continuous odom->base_link transform. The robot is also ...
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Vehicle Odometry Correction Using Lidar Contour Points (Localization)

I am currently working on a project where... Vehicle travels from point A to B GPS trajectory is used as a reference Vehicle odometry (bicycle model without slip angle beta) was used to estimate a ...
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93 views

SLAM techniques based on contact, odometry and one front camera

Consider a mobile robot provided with a contact sensor that randomly travels in a closed environment, changing direction every time an obstacle is encountered. Is it possible to reconstruct the 2D map ...
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Which scan matching algorithm can be used to extract the moving objects (in 2D lidar scanner)?

There are different types of scan matching algorithms to match consecutive 2D lidar scans, see https://youtu.be/nvFcN2-NqRc?t=421 (ICP, correlative matching, RANSAC). Most of the algorithms return the ...
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Suggestion for relevant non-complex simulator

I've recently started working on some localization algorithms like probabilistic road map and SLAM algorithms. What I'm looking for is a software that would help me in simulation for such algorithms. ...
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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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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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Do I need a camera along with LIDAR for SLAM?

Equipment: Pi 3 B Mega 2x Encoder Motor 12VDC 299RPM MPU 6050 12V bat 2000mAh LIDAR or Kinect ? I want to implement EKF SLAM. I have referred bot NOX ROS wandering robot, Hussarian CORE and Robotics ...
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Hector_Slam orientation probelm for drone

We are using Hector slam(2-D Mapping) for our drone in which we are facing some problems 1) as the orientation(axis) of the lidar changes the orientation of map changes 2) as the plane of the lidar ...
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SEIF ,online version of Graph slam create doubt in Motion Update state

I have a thesis work about Graph Slam The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures I try to implement it with the help of this paper but during the ...
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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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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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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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Usage of Falkolib(OpenSLAM) for 2D lidar landmark extraction

I am using Falkolib for landmark extraction in a 2D environment. Currently I am using the testKeypointOC executable from the bin directory. I have changed the testKeypointOC.cpp file and the ...
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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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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 optimizing a pose graph only once as opposed to optimizing a pose graph whenever loop closures are found?

I am trying to optimize a pose-graph generated through visual odometry with loop closure constraints. I wanted to know if there are any particular situations where optimizing the graph only once is ...
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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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1answer
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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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how to implement autonomous navigation using lidar and hector?

I want to make an autonomous mobile robot, which can localise itself and navigate to the goal in an unknown environment. As sensor, i just have a RPLidar to get laser scan, that's it. I used Hector ...
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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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Applying Rotation & Translation Matrix Obtained from Iterative Closest Point

Suppose I have M lidar contour points from t = k and N lidar contour points from t = k+1. (Some of you might question why I have differing number of contour points, and the reason is that these lidar ...

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