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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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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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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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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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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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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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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How does sensor fusion related to SLAM

How does sensor fusion affect the slam process?, if we have stereo camera with GPS and Imu, how does sensor fusion benefit the SLAM? Do we use sensor fusion to enhance localization phase of SLAM, and ...
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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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In SLAM loop closure, What does a sim3 matrix do?

I am confused between 3D rigid affine(with scale, without shear) transformation and Lie group's sim(3) matrix. 3D affine would be [sR|t; 0 1]. we rotate, scale and then translate a 3D point using ...
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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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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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How to understand the coordinate systems of IMU outputs in the KITTI raw data?

I am learning how to use the raw data of the KITTI data set. The raw data means that KITTI provides its raw sensor outputs. I focus that the IMU raw outputs (accelerations and angular rates) are shown ...
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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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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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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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Is it possible to implement VSLAM on Arduino?

If not, then which microcontroller will be suitable?
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Custom Image and Depth map in ROS RTAB mapper

I read about RTAB package which builds 3D point clouds based on optical odometry. This fulfills my requirement, which will be clear by the end. The issue is, I don't have a Kinect camera. What I have ...
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Hunt for fast plane extraction algorithms from sparse map points

My input was a set of sparse 3D map points(landmarks) maintained by SLAM algorithm, z-axis of the world frame permanently points to the negative direction of the ...
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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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g2o Graph optimisation, What edge to use for a distance constraint?

//cross posted from stackoverflow. If that is not ok, I will delete! I have an optimisation problem that I am trying to solve with g2o I have a data set which is N noisy Poses (XYZ), and known (less ...
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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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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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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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Looking for Beginners Tutorials on Navigation Stack and SLAM with Gazebo

As an undergrad working with SLAM algorithms, I'm looking for a step-by-step introduction to ROS navigation stack and gazebo. I am thinking of creating a simple box with a horizontal LiDAR array ...
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EKF SLAM without iterative update on observations

In Dr. Stachniss's lecture on EKF SLAM, he describes a non-iterative update method for EKF SLAM. How is this done? Can anyone explicate or provide a source on this?
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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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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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53 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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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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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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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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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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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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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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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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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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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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62 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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148 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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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. ...