Questions tagged [mobile-robot]
A robot which is capable of moving from one place to another, usually of its own volition.
624
questions
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0answers
29 views
How to actually fuse sensor using Extended Kalman Filter
Background
I'm working on 4-omniwheel mobile robot. It have encoder on each wheel and MPU 6050 IMU. The robot positioning suffer a great error because slip, so i try to increase the accuracy of ...
2
votes
1answer
44 views
Range of a heading angle [0,2π) or [−π,π)
Consider the unicycle dynamics in 2D plane:
$$\begin{array}{l}
\dot x = v\cos \varphi \\
\dot y = v\sin \varphi \\
\dot \varphi = \omega
\end{array}$$
What is the range of the heading angle $\phi$? ...
2
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0answers
26 views
Difference between CHOMP and DRL
in terms of motion planning, what are the difference between gradient-based motion planning (for instance, CHOMP http://www.nathanratliff.com/thesis-research/chomp) and deep reinforcement learning?
...
1
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1answer
49 views
Mobile robot behaviour [closed]
I want to ask people who have designed the control/behaviour system of the mobile robot? As far as I know, architecture might be implemented as a finite-state machine or a behaviour tree. What are the ...
2
votes
1answer
46 views
How to find angular velocity using pure pursuit algorithm?
I have implemented the pure pursuit algorithm for my differential wheeled robot as described in the following paper:
http://www.enseignement.polytechnique.fr/profs/informatique/Eric.Goubault/MRIS/...
1
vote
1answer
32 views
How to calculate the ground truth of your own simple dataset for testing your SLAM Algorithm?
I have tested my SLAM algorithm on EuRoC, TUM and KITTI Datasets. But I would like to test on my own custom dataset. Moreover, I already rectify how to make my own dataset in TUM dataset format, but I ...
1
vote
0answers
17 views
Rviz Status Error in Costmap: Update area outside original area
“update area outside of original map area” is the error I get when visualising the topic /move_base/global_costmap/costmap. The cost map displays correctly, there is nothing on google or the docs to ...
0
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0answers
17 views
Need help with counting the number of robots on the circumference of a circle much larger than the communication radius of the robots
I have a circle of radius 300 cm on whose circumference robots stop after moving in the environment. The robots only have a communication radius of 10 cm such that they can fit 6 robots along the ...
0
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0answers
24 views
How are landmarks updated with respect to each other in SLAM?
One thing I don't understand in EKF SLAM is how landmarks interact with each other. From my understanding this interaction only happens during a loop closing event.
When a loop closing occurs, how do ...
0
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0answers
14 views
UKF - sigma point creation - Mirroring the chol matrices
maybe this is a stupid question but i came across a problem with my ukf implementation.
I use chol() in matlab for my sigma point creation instead of the normal square root of my covariance matrix. Do ...
1
vote
1answer
34 views
How to design a behavior tree with ROS1 framework
I am confused about how high level my behavior tree has to be. For example, if I want to create an autonomous robot that goes from point A to point, what would be a reasonable behavior tree?
For now, ...
0
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0answers
18 views
UKF - Correction Step [SLAM] - Only compute the sigma point of the vehicle pose and the specific landmark that got spotted?
i want to implement an UKF Filter for SLAM but i cant seem to wrap around the update step.
When computing the innovation matrices and everything, do i need to compute the sigma points in respect to ...
0
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0answers
24 views
SLAM Initialize new landmark - specifically the covariance
Im trying to bring an EKF - SLAM to life but it keeps on failing. Specifially, I think, my mistake lies in the initialization of the new cone <-> covariance. I multiply the Jacobian (derived ...
0
votes
1answer
30 views
How to handle curved paths in maze
-I have an RPi on Ubuntu with ROS (Kinetic). The task is to solve a maze. I have implemented a left-hand algorithm to navigate through the maze.
-The robot is equipped with 3 ultrasonic HC-SR04 ...
0
votes
1answer
21 views
Extract laser scan from a map and known location
If we have the map of an environment (an occupancy grid for instance) and precisely know the pose of the robot within it. How can one reconstruct what the laser scan should look like at a given ...
0
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0answers
33 views
Fusing cross-correlated measurements for mobile robot's localization using unscented kalman filter (ukf)
I'm currently working on a mobile robot's indoor localization. On the perception side, I can only rely on a 2D lidar and wheel odometry.
I have used these sources as input of different localization's ...
0
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0answers
11 views
What is the mathematical relation between phi1, phi2, phi3 and motor PWM values for 3 wheel omni drive robot?
My question is that I cannot deduce the relation between phi1, phi2, phi3 values of the omni robot (3 wheeled) and the motor's PWM values, since I'm planning on designing the robot to perform "go ...
0
votes
2answers
22 views
Sprockets for steering
I'm planning to drive the steering of a AWD rover using stepper motors. Is it usually a good idea to use sprockets and chains for that? Would the precision typically be too low for steering? The ...
0
votes
0answers
27 views
Is Image Based Visual Servoing a non-linear controller?
Is Image Based Visual Servoing a non-linear controller? I think it is as the Image Jacobian has square terms of u & v (image-plane coords).
Where $p_u, p_v$ are the width & height of each ...
0
votes
1answer
26 views
Compute how well a laser scan matches or overlaps with its environment given a map of the environment and location of the robot is known
If I knew the exact location of my robot and have an accurate map (for eg. an occupancy grid map) of the environment beforehand, how can I compute a measure of how well the laser scan data agree with ...
1
vote
1answer
40 views
How do I compute the feedforward terms in a control law using Matlab?
I have the following situation. I have computed the linear and angular velocity which are the controls for a mobile robot, which have the form:
$v_d=v_{fb}+v_{ff}$
$\omega_d=\omega_{fb}+\omega_{ff}$
...
0
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0answers
23 views
Robot movement between point A and B with fixed angle and step length
I am working on a robotic path finding problem for my personal project and I am stuck on how to get from point A to point B.
Please note that this is a visual robot, as I am looking to implement it ...
0
votes
1answer
37 views
Matlab code to take time derivatives
I have a velocity command, which is:
$v=k_1\rho cos(\alpha)$
where each quantity $\rho$ and $\alpha$ depend by the time.
I would like now to take the time derivative of this, in order to use it as ...
0
votes
1answer
57 views
How do I apply a disturbance observer to a mobile robot?
I have to design a observer to estimate disturbances which are applied to a unicycle model. So, the unicycle model with disturbances is:
$\dot{x}=v cos\theta + d_x$
$\dot{y}=v sin\theta + d_y$
$\dot{\...
0
votes
1answer
53 views
Robots and RTOS
Many computing platforms used by robots are not real time(ex Jetson).
How are real time constraints handled in real robots? Are all software transfered into a hardware solution with real time ...
0
votes
1answer
37 views
Calculate body speed in m/s with weight in the equation?
UPDATE: I have clarified my question for answerers to better understand what I am asking
If I have a flywheel, like the one shown in this image, and I know the torque, weight distribution, and weight. ...
3
votes
1answer
30 views
Worm gearbox for steering
I'm planning on making a smallish off-road rover (15-25kg net weight) with 4-wheel steering and I was wondering if it'd be a good idea to use (self-locking) worm gearboxes for steering. I've thought ...
1
vote
1answer
194 views
Hector_navigaton on ROS Melodic error
I'm a newbie on robotics, and currently, I'm working on a project to make an autonomous robot that can mapping the surrounding environment and decide the shortest route towards the goal while avoiding ...
0
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0answers
24 views
What are the best approaches and limitations for calculating the Inverse dynamics for a floating base quadruped?
Given a quadruped standing on all fours, or trotting with 2 legs down/2 up, I've seen a few methods of computing inverse dynamics. All derive from centroidal momentum physics, and I think all distill ...
0
votes
1answer
56 views
Problem designing acceleration inputs controller
I am reading this paper: https://www.researchgate.net/publication/224635390_The_motion_control_problem_for_the_CyberCarpet
in which is implemented a cartesian regulator to bring the position $(x,y)$ ...
1
vote
1answer
42 views
How to estimate proper heading angle
I obtain the heading or yaw angle from a source which I am not allowed to modify, but when the angle goes more than +180 or -180, it interchanges either from 180 to -180 or the other way around. Any ...
0
votes
1answer
12 views
Determining Base Configuration Tsb from End-Effector Configuration Tse for youbot
Hello there, hope you are doing great.
Right now I am trying to control youbot to pick and cube and place it to a certain position, on simulation. However, I believe that the reference trajectory is ...
0
votes
1answer
219 views
How to implement a 4 Mecanum wheel Robot kinematic model Practically in code?
Above is the Kinematic model of a 4 wheeled from https://cdn.intechopen.com/pdfs/465/InTechOmnidirectional_mobile_robot_design_and_implementation.pdf, My question is how to use these kinematic ...
1
vote
1answer
309 views
How to do odometry for 4 mecanum wheeled robot?
I need to do odometry for a 4 mecanum wheeled robot for indoor applications. Is it possible to do it with just wheel encoders and IMU sensors? If possible, how? It will be of great help if someone ...
0
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1answer
55 views
How do I call Matlab code into Simulink for doing a simulation for doing plots?
I have built a simulink model for performing cartesian regulation on a unicycle:
and plot the results with a Matlab code
but, I am not very confident with Simulink and so I don't know how to call ...
0
votes
1answer
35 views
error with dimensions in Simulink
I am trying to simulate a cartesian regulator for a unicycle with Simulink and I am having some problems.
My simulink model is the following:
and when I run it I get the following error message:
so ...
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0answers
29 views
Robotic Platforms Similar to the PiBot(Locobot)
I am brain storming platforms to use for a project I am working on. I'm looking for an mobile platform with a manipulator attached. I originally was focusing on the PiBot, but after doing some ...
4
votes
1answer
50 views
Universities offering courses about Drones (Unmanned Aerial Vehicles [UAVs]) [closed]
I am trying to gather some information about university courses offered about drones (or Unmanned Aerial Vehicles).
At the beginning, I thought that I would have found way more than what I found and ...
4
votes
0answers
93 views
Likelihood field sensor model (Probabilistic Robotics, Thrun et al., p.169-174)
I am currently working on the "likelihood field" sensor model (aka "endpoint model") by Thrun et al. (book: Probabilistic Robotics, Thrun et al., p.169-174)
In this context I have ...
1
vote
3answers
84 views
irobot create 2: random changes in driving speed
I am trying to make the Create2 dance a specific choreography. I´m not using the sensors, I just let it drive and turn for a specific amount of time. In general it works fine.
But after working with ...
0
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0answers
21 views
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 $$P =
{\begin{bmatrix}
0 & -1 & 0 \\
0 & 0 & -1 \\
1 & 0 & 0
\end{bmatrix}}^{-1}$$
...
1
vote
1answer
54 views
Where to buy cheap motors and mechanical parts for hobby robotics applications? [closed]
My kids want to get into robotics, where Online can I buy the motors (dc,ac,stepper...) and mechanical assembly (nuts, bolts, sheet metal, springs, rods...) for a very affordable price, you know I ...
0
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0answers
17 views
What should be a good frequency for the EKF prediction and correction updates?
This is my first post on the forum although I read Q&A posted here constantly. I haven´t seen a similar question so here it goes:
I am implementing an EKF for localization from scratch just for ...
2
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0answers
51 views
How to properly model a non-holonomic system?
I'm trying to model a robot which is composed of a non-holonomic and a holonomic system overall is non-holonomic. Basically it's a robot arm + mobile platform. So far I have found a similar work like ...
0
votes
1answer
42 views
Jetson TX2 vs small form factor PC for autonomous robots
What are the advantages and disadvantages for each?
I can build a small form factor PC with a GTX 1050 which will easily out perform a jetson for the same price.
When and where are each more ...
0
votes
0answers
19 views
sampling-based path planning approach
I have been doing a project on robot path planning. A question has arisen in my mind during the project
What are the state of the art sampling-based path planning schemes for the dynamic environment?
...
0
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0answers
35 views
ICP results as command in odometry motion model
im going through the odometry motion model proposed by Thurn in Probabilistic Robotics famous book and i have some questions concerning the kind of command that we can use. I will explain more my ...
0
votes
1answer
42 views
digital servo won't seek to angle if delta between current position and target is more than ~15 degrees
My students and I are using a Hiwonder LD-220MG digital servo to position a "shoulder" on a robot.
We are seeing a behavior (on every one of these servos that we test) that it won't go ...
0
votes
1answer
37 views
Differential Drive Tricycle WMR with active caster wheel
I'm doing some research for my university project and in particular it concerns a functional design project. I thought it would have been possible to design a 3-wheel mobile robot with an active ...
0
votes
1answer
48 views
How can I get the equations of motion used in webots?
I am trying to use the webots platform for developing controllers. I need the differential equations governing the motion of the robots. How can I get the equations of motion used in webots?
