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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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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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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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37 views

Technologies needed for indoor and outdoor navigating robot

Before I begin, I should add that I am a complete beginner in robotics and hope that I can figure out where I should start by asking this question. I am trying to make a robot that is able to ...
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1answer
36 views

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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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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47 views

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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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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Jacobian of $ (\textbf{e}^{[\boldsymbol{\xi}] _\times}\textbf{T})^{-1}\textbf{p}$ wrt $\boldsymbol{\xi}$

The chain rule is always confusing. Is the following derivation correct? \begin{equation} \frac{\partial (\textbf{e}^{[\boldsymbol{\xi}] _\times}\textbf{T})^{-1}\textbf{p}}{\partial \boldsymbol{\xi}}...
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1answer
44 views

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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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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38 views

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
70 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
30 views

How to perform active search in point feature based monoSLAM?

I am modifying an implementation of SLAM with single camera, MonoSLAM [1]. Instead of image patches, I want to use features points (ORB) to track landmarks. MonoSLAM uses a EKF framework. So for ...
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Inexpensive & minimally viable systems for testing SLAM algorithms?

I've been studying SLAM on my own for some time, I can sift through texts over texts and try my best understanding them. However, without actually implementing them myself, I think I still don't fully ...
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36 views

How to calculate observation matrix Jacobians in EFK based mono slam? What are projection Jacobians?

I have been trying to understand an implementation of monoSLAM 1. But my question is generic to EKF based single camera SLAM. My Jacobian calculation leads to complex and lengthy expressions while ...
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1answer
41 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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Convert sonar scans to Lidar scan file

Has anyone tried to map environments using Sonars or 1D ToF sensors? Since it's very difficult to implement such an algorithm from the scratch, I'm planning to use an existing ROS packages such as ...
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1answer
74 views

Robot moving on a flat floor - 2D or 3D SLAM?

What is the best way to model the SLAM problem (offline) for a wheeled robot moving on a flat floor in 3D space (the pose has only 3 degrees of freedom)? In terms of sensor data, we have the wheel ...
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1answer
58 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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92 views

smooth robot 3D trajectory using graph optimization

I want to solve a trajectory smoothing problem using graph optimization. I have asked questions on how to solve this problem in a previous post and got directed towards using graph optimization. I ...
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How to cope with an optical window limitation on 2D LiDAR?

I have a very small and cheap robot and I wanted to mount a 2D LiDAR on a bottom of it (3cm above the ground). It seems to be great as during the mapping the lidar will detect even small elevations ...
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Map initialization problem in Mono SLAM

I'm reading and trying to implement the paper Monofusion(V. Pradeep, C. Rhemann, S. Izadi, C. Zach, M. Bleyer and S. Bathiche, "MonoFusion: Real-time 3D reconstruction of small scenes with a single ...
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3answers
118 views

smoothing the robot poses inbetween two known poses

I have a set of N robot poses between point A and B. I use a global localization technique to estimate poses at point A and B. As a result, I have a new corrected pose B'. Please see the figure below. ...
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Fiducials in conjuction with AMCL

I'm having some trouble getting fiducials (using aruco_detect) to work alongside amcl. The goal here is to use normal amcl localization when a fiducial is not present, and to switch to localization ...
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112 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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1answer
25 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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1answer
177 views

IMU and Camera Synchronization

I would like to synchronize my IMU and Camera sensors for my real-time visual-inertial SLAM algorithm in ROS. I am streaming video at 30 Hz from an android phone through IP address. IMU, however, has ...
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0answers
37 views

EIF slam algorithm implementation as per Probabilistic Robotics

I want to implement EIF slam from Probabilistic Robotics Table 11.2. This is the algorithm for EIF slam. To construct $\Omega and \xi$ matrix I write down a Java code. Here is my code ...
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2answers
50 views

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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How to calculate a covariance of trajectory?

I have a drifted LiDAR odometry $^w \textbf{T}_{1:k}\in SE(3)$ and a drift corrected LiDAR odometry $^w \textbf{T}'_{1:k}\in SE(3)$ by a loop closure where w represents the reference world frame. ...
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2answers
188 views

Mobile robot navigation without static map

I am working on an autonomous mobile robot based on ROS. All the tutorials and examples requires a static map which need to be generated in order to do the localization and mapping. Do i need to ...
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0answers
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Lost on SEIF Slam repeated update landmark

I am working on Sparse Extended Information Slam. I take the reference from Probabilistic Robotics, by Dr.Sebastian Thrun (Chapter 12,page 303). I have some doubt about the implementation of the ...
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1answer
33 views

SEIF slam: Effect on information matrix when there is no landmarks

I studied about Sparse Extended Information Filter slam. I want to clarify some points regarding this topic. As per the sparse extended information(SEIIF) slam when the robot sees some landmarks it ...
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1answer
34 views

EKF Slam algorithm doubt at observation update

I have some doubt on EKF Slam with known correspondence in the measurement update state. I follow the algorithm from Probabilistic Robotics by Sebastian THRUN. This Algorithm is on Chapter 10 page No:...
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1answer
65 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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1answer
130 views

Is this SLAM performance typical or am I doing something wrong?

I'm experimenting with SLAM for the first time. I am using ROS on a Turtlebot3, which has a Raspberry Pi and a single Lidar sensor, Robotis LDS-01. I am running a configuration with three computers, ...
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1answer
45 views

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
79 views

Fixing the first node in Graph-based SLAM

The first node in the graph SLAM should be fixed. The famous "a tutorial on graph based slam" paper is showing that we can fix a node by adding identity matrix. Why adding identity to the Hessian of ...
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2answers
50 views

provide world map for ekf global localization problem

I am trying to implement the ekf_localization algorithm in page 217 (Table 7.3) of the probabilistic robotics book by Thrun. From my previous post, I understand that I need to extract observed ...
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1answer
99 views

EKF localization data association

I am working with ROS indigo and clearpath huskyA200 and wanted to implement the EKF localization with unknown correspondences with my own hokuyo lidar data for a school project. Giving the algorithm ...
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1answer
46 views

Relation between GraphSLAM and Iterative closest Point algorithm

I have lots of doubts about GraphSLAM, The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. When I practically implement it I get matrix singularity error. I taken ...
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1answer
120 views

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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2answers
90 views

GraphSLAM equation doubt

I have question about GraphSLAM implementation. To find out the path and map using GraphSLAM we rely on this equation: $$\mu=\Omega^{-1}\xi$$ where $\Omega$ is our information matrix which ...
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1answer
60 views

Graph Slam Landmark remove and then again add it

I try to implement Graph Slam in real dataset. My data set have some data that describe that the Robot observe same landmark over and over with a large amount of time difference. Prof. Sebastian ...
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2answers
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How to detect loop in robot movement observing odometer data

I have some odometer data. This data are based upon robot movement. I can transfer those raw data to a motion equation from where I get x,y,and theta co-ordinate of a Robot. If I plot those x,y ...
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1answer
127 views

Multiple View Triangulation method used by COLMAP

I'm looking at how COLMAP does multi-view triangulation. I can't work out what this function is doing. I can't find any formulas which look similar. The input "proj_matricies" come from pose data, the ...
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1answer
69 views

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
165 views

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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1answer
56 views

How to generate Particle in Particle Filter

I try to implement FastSlam 1.0. To implement this I need to create particles. Now my confusion is that How to create Particles?I have some odometry and Measurement data. Using those data values how ...