Skip to main content

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.

Filter by
Sorted by
Tagged with
28 votes
8 answers
18k views

Absolute positioning without GPS

Using an IMU a robot can estimate its current position relative to its starting position, but this incurs error over time. GPS is especially useful for providing position information not biased by ...
Robz's user avatar
  • 2,162
18 votes
4 answers
14k views

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 ...
Mehdi's user avatar
  • 681
16 votes
2 answers
8k views

Difference between Rao-Blackwellized particle filters and regular ones

From what I've read so far, it seems that a Rao-Blackwellized particle filter is just a normal particle filter used after marginalizing a variable from: $$p(r_t,s_t | y^t)$$ I'm not really sure ...
Ash's user avatar
  • 420
16 votes
1 answer
977 views

How do SLAM algorithms handle a changing environment?

I'm doing some groundwork for a project, and I have a question about the current state of SLAM techniques. When a SLAM-equipped device detects an object, that object's position is stored. If you look ...
anaximander's user avatar
16 votes
2 answers
2k views

EKF-SLAM Update step, Kalman Gain becomes singular

I'm using an EKF for SLAM and I'm having some problem with the update step. I'm getting a warning that K is singular, rcond evaluates to ...
munk's user avatar
  • 777
15 votes
3 answers
814 views

How to determine quality of ICP matches?

In SLAM frontends which use the Iterative Closest Point (ICP) algorithm for identifying the association between two matching point clouds, how can you determine if the algorithm is stuck in a local ...
Jakob's user avatar
  • 3,054
13 votes
1 answer
590 views

What is the difference between SAM and SLAM?

What is the difference between Smoothing and Mapping (SAM) and Simultaneous Localization and Mapping (SLAM)? These general approaches seem closely related. Can someone describe the differences?
Stefan's user avatar
  • 231
13 votes
4 answers
6k views

How to obtain dense point clouds from stereo cameras?

I am trying to use a stereo camera for scene reconstruction, but I can usually only obtain sparse point clouds (i.e. over half the image does not have any proper depth information). I realize that ...
georgebrindeiro's user avatar
10 votes
1 answer
572 views

Who coined (or popularized) the term "SLAM"?

According to Wikipedia's article on SLAM, the original idea came from Randal Smith and Peter Cheeseman (On the Estimation and Representation of Spatial Uncertainty [PDF]) in 1986, and was refined by ...
Ian's user avatar
  • 11k
10 votes
2 answers
1k views

The relationship between point cloud maps and graph maps

I am most familiar with SLAM maps that are point clouds, usually in the form of a vector like $<x,y,\theta,f_{1x},f_{1y},...,f_{nx},f_{ny}>$. I also understand how to create a map like this ...
munk's user avatar
  • 777
10 votes
1 answer
350 views

Least squares map joining

There is a lot of background here, scroll to the bottom for the question I am trying out the map joining algorithm described in How Far is SLAM From a Linear Least Squares Problem; specifically, ...
munk's user avatar
  • 777
10 votes
1 answer
345 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-...
T.A. Eady's user avatar
  • 101
9 votes
3 answers
2k views

What algorithm can I use for constructing a map of an explored area using a number of ultrasound sensors?

Ultrasound sensors are incredibly cheap these days which makes them a popular choice for many hobbyist robotic applications, and I'd like to use a bunch of them (say 10) around a robot with an ...
berry120's user avatar
  • 1,265
9 votes
3 answers
2k views

How can I improve the map in my Mobile Autonomous Robot using KINECT

A little background of my aim I am in the process of building a mobile autonomous robot which must navigate around an unknown area, must avoid obstacles and receive speech input to do various tasks. ...
Shreyas Kapur's user avatar
8 votes
4 answers
2k views

In EKF-SLAM, why do we even need odometry when there is a more reliable sensor?Also, are all SLAM algorithms feature-based?

In the book of SLAM for dummies, why do we even need the odometry when the robot would use the data retrieved from the laser scanner which is more accurate than odometry? Why not just rerly on the ...
Xegara's user avatar
  • 251
8 votes
5 answers
17k views

How computationally powerful is an Arduino Uno board?

What can an Arduino board such as the Uno really do? Of course simple things like controlling a couple servos is very easy for it. However, I don't think an Uno board would be able to preform real-...
golmschenk's user avatar
  • 1,564
8 votes
3 answers
2k views

SLAM without landmarks?

First, is it possible to build map without landmarks for a robot in 2D? Let's say we have an aisle surrounded by two walls. The robot moves in this environment. Now is it feasible to build such a ...
CroCo's user avatar
  • 2,453
8 votes
2 answers
6k views

SLAM : Why is marginalization the same as schur's complement?

Consider the system $$ \tag 1 H\delta x=-g $$ where $H$ and $g$ are the Hessian and gradient of some cost function $f$ of the form $f(x)=e(x)^Te(x)$. The function $e(x)=z-\hat{z}(x)$ is an error ...
Ash's user avatar
  • 420
8 votes
1 answer
2k views

SLAM: Why use two cameras (stereo) if SLAM can be done using single camera (monocular)?

I am aware that algorithm for monocular SLAM is complex compared to stereo SLAM. But my question is if by any means it is possible to do SLAM using one camera why one should use two cameras to do the ...
vacky's user avatar
  • 417
8 votes
2 answers
2k views

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 ...
Vinmean's user avatar
  • 173
8 votes
1 answer
2k views

What is the best way to fuse measurements from IMU, LIDAR, and Encoder information in some recursive bayesian filter?

I am doing SLAM with a four wheeled (2-wheel drive) differential drive robot driving through some hall way. The hallway is not flat everywhere. And the robot turns by spinning in place, then traveling ...
chibro2's user avatar
  • 235
7 votes
3 answers
6k views

Difference between SLAM and "3D reconstruction"?

I'm reading this paper: http://arxiv.org/abs/1310.2053 (The role of RGB-D benchmark datasets: an overview) and see the following words: Thanks to accurate depth data, currently published papers ...
zhangxaochen's user avatar
7 votes
1 answer
936 views

Noise in motion and measurement models

When using an EKF for SLAM, I often see the motion and measurement models being described as having some noise term. This makes sense to me if you're doing a simulation, where you need to add noise ...
munk's user avatar
  • 777
7 votes
1 answer
7k views

Are there any advantages to using a LIDAR for SLAM vs a standard RGB camera?

I've been thinking about building a small UAV with an onboard LIDAR, just for fun. I'm interested in SLAM and autonomous flight indoors and thought that I would need a lidar to get a 3D map of the ...
user avatar
7 votes
2 answers
110 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 ...
John M.'s user avatar
  • 563
6 votes
3 answers
1k views

Is an accelerometer sufficient to detect displacement, or do I need an INS?

Do I need a complex system (of gyros, accelerometers etc.) to detect if a robot has moved forward or can I simply use an accelerometer. I'm building a robot that learns to walk and I need to detect ...
Jordan's user avatar
  • 911
6 votes
1 answer
5k views

Build a ROS robot with SLAM without laser

I've build a simple wheeled robot based on two continuous servos, controlled by Raspberry Pi running ROS-groovy, with a smart phone mounted on top to provide additional sensors. I'd like to situate ...
Bill's user avatar
  • 183
6 votes
1 answer
693 views

Comparing maps to groundtruth

When you've created a map with a SLAM implementation and you have some groundtruth data, what is the best way to determine the accuracy of that map? My first thought is to use the Euclidean ...
munk's user avatar
  • 777
6 votes
1 answer
215 views

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:...
rotating_image's user avatar
6 votes
1 answer
1k views

LIDAR Points as Landmarks

I am currently trying to implement a GraphSLAM/SAM algorithm for LIDAR. From papers I've read, you generate a directed graph from expected LIDAR measurements to landmarks similar to the image below (...
d.mc2's user avatar
  • 171
6 votes
2 answers
321 views

Ensemble Kalman Filter SLAM

I know that there is an extended kalman filter approach to simultaneous localization and mapping. I'm curious if there is a SLAM algorithm that exploits the ensemble kalman filter. A citation would ...
Paul's user avatar
  • 1,278
5 votes
3 answers
4k views

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 ...
John Bow's user avatar
5 votes
1 answer
3k views

Understanding Drift in Simultaneous Localization and Mapping (SLAM)

I am trying to understand the effect of drift in Simultaneous Localization and Mapping (SLAM). My understanding is that drift occurs because the robot tracks its position relative to a set of ...
Karnivaurus's user avatar
5 votes
2 answers
371 views

Why do we need to know the translation between Camera and IMU?

In Visual Inertial Odometry, assuming the camera and the IMU are attached to the same rigid body, why isn't it enough to know just the relative rotation between the camera and the IMU? Why do we need ...
jordi's user avatar
  • 173
5 votes
1 answer
2k views

role of chi2 in SLAM back-end optimization

All-most all SLAM back-end implementation compute chi2 estimates. Chi2 computation is usually used to compute the best-fitness score of model to the data. How it is related to optimization framework ...
nkd's user avatar
  • 53
5 votes
3 answers
1k views

How can I implement tremaux algo in arduino line follower to navigate and create map?

The Map1 The task is divided into 2 runs, In first run, We have to navigate through whole map and reach the end mark taking all checkpoints. In second run, using the mapping from first run we have to ...
Saransh's user avatar
  • 81
5 votes
2 answers
4k views

How to use SLAM with simple sensors

What 2D SLAM implementations (preferably included in ROS) can be used with simple distance sensors like IR or ultrasonic rangefinders? I have a small mobile platform equipped with three forward ...
Cerin's user avatar
  • 294
5 votes
2 answers
447 views

SLAM for Autonomous car

I am working on SLAM for autonomous car like vehicles with 2D lasers and IMU (deriving odometry). I would like to know how efficient is using the existing SLAM algorithms (for example: gmapping in ...
nayab's user avatar
  • 384
5 votes
1 answer
2k views

Marginalization in Graph SLAM [duplicate]

I have several questions about the process of marginalization in SLAM algorithms: 0 - What are the mathematic intuition behind marginalization process 1 - I know marginalization of states or points ...
Ricardo Achilles's user avatar
4 votes
6 answers
8k views

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....
zhangxaochen's user avatar
4 votes
2 answers
2k views

the uncertainty of initializing new landmark in EKF-SLAM

In EKF-SLAM (based-feature map) once the robot senses a new landmark, it is augmented to state vector. As a result, the size of the state vector and the covariance matrix are expanded. My question is ...
CroCo's user avatar
  • 2,453
4 votes
4 answers
2k views

Which micro-controler/processor to be used for autonomous stereo vision robot system?

I am very new two robotics, however I have a working stereo algorithm which I want to combine with a SLAM algorithm. I am developing this system for an other application but I decided integrating it ...
Svenja Woicke's user avatar
4 votes
4 answers
5k views

Which is a good and cheap 3D LIDAR or other options? [closed]

Our team is planning to go for European Rover Challenge (ERC) 2018 for which we are designing an Autonomous rover. In order to implement SLAM, we need a way of mapping (with a range of atleast 2-4 ...
Abhishek Dinesan's user avatar
4 votes
1 answer
3k views

What is the difference between Positioning and Localization Systems

I would like to know what are the differences between Positioning and Localization Systems. In most review papers they are used interchangeably. Are they the same? For example: GPS(Global Positioning ...
acs's user avatar
  • 1,124
4 votes
3 answers
3k views

Is there any advantage to velocity motion models over odometry motion models for SLAM?

I've seen several examples of SLAM algorithms (EKF SLAM, Graph SLAM, SEIF SLAM) written in terms of the velocity motion model. I have yet to see an example of any SLAM algorithm utilizing the ...
Paul's user avatar
  • 1,278
4 votes
2 answers
449 views

Comprehensive comparison of SLAM algorithms

I'm looking for a research paper or series of papers that compare the performance of various simultaneous localization and mapping algorithms for rovers in a variety of real world environments. In ...
Paul's user avatar
  • 1,278
4 votes
3 answers
358 views

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 ...
PagMax's user avatar
  • 145
4 votes
2 answers
160 views

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. ...
badrobot15's user avatar
4 votes
2 answers
1k views

What's the difference between factor graph optimization and bundle adjustment?

I see that in SLAM literature, factor graph optimization is frequently used. While in Structure from Motion (SfM) literature , they usually use bundle adjustment. What's the difference between the two ...
zhouch's user avatar
  • 41
4 votes
1 answer
3k views

ROS AMCL does not need odometry data?

I'm reading amcl document on ROS Wiki. In its subscribed topics there is not odometry topic, why? It works only with laser? Subscribed Topics: (From ROS Wiki) scan (sensor_msgs/LaserScan) tf (tf/...
Maysam's user avatar
  • 345

1
2 3 4 5
33