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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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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131 views

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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Setting An Initial Pose Rotation In ORB SLAM2

I am running ORB SLAM 2 on a drone with a downward facing, RGBD camera. I'm using Gazebo to simulate and Rviz to see the vision_pose ROS topic (the orientation/...
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Do IMU have value in SLAM?

IMU are often used in theoretical models involving SLAM. I'm a bit confused on their practical value since error accumulation is so bad that after a couple seconds you need to completely ignore it. ...
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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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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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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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What are the state-of-the-art variants of the basic ICP algorithm for point cloud registration?

The questions is quite straightforward. For the past few days I've been looking into point cloud registration. It looks like it all started with the basic ICP algorithm as described in P. J. Besl and ...
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What is the state-of-the-art approach to detect moving objects from mobile robot with 2D Lidar only?

Having a setup of a mobile robot with a 360° 2D lidar (1 plane). What is the current easiest approach to detect moving object with a high reliability from a moving robot? To make it simple, we ...
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38 views

How do robots move parallel to a wall/line?

I have been studying robotics by myself, lately. I noticed that there are various mapping, localization methods (popularly under SLAM), but are there concepts relating to the robot moving in a ...
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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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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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111 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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How to get 2D map using Stereoscopic camer (RGB+D), IMU and GPS?

I am starting with slam using imu, stereo camera (that gives RGB + depth info) camera and gps mounted on my robot. I wish to create a 2D map for it like this: But with landmarks, so that I can stop ...
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How do I calculate the direction robot is facing, pose from velocity and yaw rate?

I have a simple car robot with four wheels moving relatively slowly (5~10 mph). The robot has a velocity magnitude and yaw rate sensor and the sensor samples about every 0.1 seconds. I want to map the ...
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781 views

How do I evaluate the minimum requirements of the processor and camera for a visual SLAM robot?

I would like to build a visual SLAM robot (just for self-learning purpose) but I get frustrated how I know which processor and camera should be used for visual SLAM. First, for the processor, I have ...
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Improvements over FastSLAM2.0

Are there some papers and/or works that describe improvements for the FastSLAM2.0 algorithm? I'm particularly interested in the following areas: The map is completely unknown at the beginning of the ...
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Do self-driving robots use object-level SLAM?

How do self-driving bots usually deal with transient objects, e.g., parked cars on the side of roads when they can come and go? These aren't moving objects at the time of capture, but they do move at ...
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34 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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25 views

How to deal with Gaussian Errors, which don't have a mean value of 0?

I'm writing a SLAM algorithm. One of the main problems is, that the landmark measurement error is not really Gaussian distributed, which means, their error doesn't have a mean value of 0. I already ...
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Triangulation: Ceres solver minimizes only the last residual block

I have been attempting to estimate a bunch of 3d coordinates viewed via a multi-view setup with known poses, I have the code running, but the output of ceres seems baffling. There are 7 image frames/...
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When a permutation matrix is desired for transforming camera frame to world frame?

When dealing with rectified images, why would the inverse of a simple permutation matrix $$P = {\begin{bmatrix} 0 & -1 & 0 \\ 0 & 0 & -1 \\ 1 & 0 & 0 \end{bmatrix}}^{-1}$$ ...
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How does isam compare with Gmapping and Hector?

I read about incremental smoothing and mapping (iSAM) first in the paper on hector_slam (a flexible and scalable SLAM system with full 3D motion estimation by Stefan Kohlbrecher et al) and then read ...
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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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304 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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EKF SLAM : SLAM specific Jacobians for new landmarks

I am currently trying to understand the books SLAM for dummies and Simulataneous localization and mapping with the extended Kalman filter to implement slam. I have understood steps 1 and 2 SLAM for ...
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57 views

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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Transforming a 3x3 Covariance Matrix to 2x2

Hello friends of the robotics, for Data Association I have the Robots cov matrix in a 3x3 Form, but the measurements and landmarks only in 2x2. I want to compute the Mahalanobis distance, so how ...
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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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211 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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197 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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How is the depth estimation done in DTAM / LSD-SLAM (direct VSLAM)?

I know that DTAM and LSD-SLAM both employ the photometric error between two keyframes to estimate the image depth. But I don't know what the photometric error describes precisely. In the DTAM paper, I ...
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How does loop closure backpropagate the robots states into prior times?

I have read some about loop closure and I am somewhat confused. Suppose we implement something like EKF slam using LIDAR and suppose loop closure is aided by computer vision based features so that if ...
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112 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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64 views

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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239 views

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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How to correctly use [VertexSE3Expmap] as two connecting Vertex in Edge_V_V_GICP?

I am working on a pose estimation problem solved by Levenberg-Marquardt with g2o. I want to build 3D rigid constraint between two pose, so I choose Edge_V_V_GICP and test the g2o/examples/icp/...
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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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74 views

How does sensor fusion related to SLAM?

How does sensor fusion affect the SLAM process? If we have a stereo camera with GPS and IMU, how does sensor fusion benefit the SLAM? Do we use sensor fusion to enhance the localization phase of SLAM, ...
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1answer
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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1answer
69 views

The biases in the state vector of Extended Kalman Filter(EKF)

I am reading one paper on observability Observability Analysis of Aided INS with Heterogeneous Features of Points, Lines and Planes. The state vector contains the current IMU state and the feature ...
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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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76 views

Why innovation equation in Extended Kalman filter is called innovation? [closed]

In the Extended Kalman filter for SLAM, why the innovation equation is called innovation? Is there any reason behind it?
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21 views

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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Should I wrap the intrinsic and extrinsic parameters to a single vector during optimization?

I've read the libmv library dedicated to solving the bundle adjustment problem. The author states it's better to wrap the rotation and translation parameters into a single vector during optimization ...
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54 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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32 views

Motion model and homogeneous transformation issue on a drone

I am trying to develop a EKF-SLAM algorithm for a drone, and I want to estimate its position in the inertial/world reference frame. I have as control variables the linear and angular velocities in the ...
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What does the normalized image coordinates imply?

In VSLAM or visual odometry, we use a camera matrix P to transform 3D scene points to 2D image points. When using homogeneous representation, we may choose the image coordinates as the normalized ...

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