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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1answer
180 views

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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1answer
94 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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168 views

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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766 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 ...
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49 views

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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93 views

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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1answer
128 views

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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1answer
154 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:...
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1answer
79 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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170 views

Is it possible to implement VSLAM on Arduino?

If not, then which microcontroller will be suitable?
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1answer
373 views

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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2answers
142 views

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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1k views

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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282 views

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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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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1answer
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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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453 views

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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1answer
155 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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2answers
715 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
28 views

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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2answers
95 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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115 views

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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1answer
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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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1answer
100 views

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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1answer
164 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
257 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
49 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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0answers
224 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
361 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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1answer
152 views

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
221 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
89 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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1answer
277 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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2answers
108 views

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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0answers
78 views

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
238 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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1answer
42 views

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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1answer
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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1answer
179 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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0answers
74 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
155 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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0answers
104 views

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
1k 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
32 views

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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2answers
112 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
145 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
162 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
622 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
65 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
117 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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