Questions tagged [mobile-robot]
A robot which is capable of moving from one place to another, usually of its own volition.
605
questions
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1answer
14 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 ...
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0answers
13 views
Calculate body speed in m/s with weight in the equation?
How can i calculate the speed of a body with the parameters of: wheel diameter, motor RPM and body weight, and in turn get the answer in meters per second?
This is all I have to far:
I just need to ...
2
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1answer
16 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 ...
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2answers
40 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 ...
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0answers
11 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 ...
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0answers
16 views
Are all mobile robots with a non-holonomic constraint differentially flat?
I am studying mobile robots, and I have seen that for this type of robots we can plan a trajectory using the fact that some of those are differentially flat. This means that we can plan a trajectory ...
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1answer
40 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
31 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 ...
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1answer
10 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
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1answer
51 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 ...
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1answer
52 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 ...
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1answer
46 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 ...
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1answer
20 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
28 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
49 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
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0answers
52 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 ...
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vote
3answers
51 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 ...
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0answers
19 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
48 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 ...
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0answers
14 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
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1answer
36 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 ...
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0answers
17 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?
...
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0answers
30 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 ...
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1answer
31 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
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1answer
24 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
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1answer
33 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?
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0answers
34 views
How to avoid hair entanglement in your robot wheels?
This isn't about any complex math or physics of robots, but rather an annoying practical issue I don't find much information about.
My robot works indoors (house, office) and there's certainly going ...
0
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0answers
14 views
Drone based CV via base station - power requirments
Currently computer vision based inference is impractical on a drone given the significant power draw.
Is connecting a drone to a base station which does CV a viable solution to this issue? Has it been ...
1
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3answers
39 views
Occupancy grid maps
Why do we take probabilistic approch to model the environment for robots in occupancy grid maps.The assumption is always taken that each cell on the grid map is either free or occupied.So why have ...
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0answers
13 views
problem in understanding this part of the RRTx path finding algorithm
this is a paragraph from the paper of the RRTx algorithm
and below it a figure referenced in the paragraph
however the No and Nr nodes types are unclear to me what are they exactly ?
0
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3answers
43 views
How to avoid false encoder counts due to vibration in robot?
I have a couple of motors on my mobile base other than the drive motors, and they tend to create vibration in the robot. When these motors are turned on, the wheel's encoder ticks increase without any ...
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0answers
25 views
Serial communication of IMU and Encoder arduino code
Pls, I need people to help me look at where I am getting it wrong. I test this code on Arduino ide and got the result I wanted but sending it to Matlab through serial communication, I obtained a ...
3
votes
1answer
50 views
Do mobile robots use variable transmissions?
I've built a simple robot that can move. I'm using brushless motors. I've realized that at slow speeds the motors pull a lot of current. I didn't understand the power / current / efficiency charts ...
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0answers
23 views
Degree of maneuverability mobile robot
According to the traditional kinematic theory for mobile robots [1][2] a mobile robot with a steerable wheel and two passive casters presents a $\delta_m=2,\delta_s=1,\delta_M=3$. This is easy to ...
0
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2answers
38 views
HTTP requestes for Robot Teleoperation
I'm new to this forum so I apologise if I disrespect some rules. I am considering using HTTP requests to control a robot remotely. The design problem I am trying to solve is that I would like to ...
0
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1answer
35 views
Motion of a mobile platform inaccurate than industrial robot arm
It is known that with a 7DoF industrial you can achieve an accuracy of ~2mm.
However, the motion with a mobile platform is known to be more inaccurate and expensive.
I can follow why the motion is ...
0
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0answers
18 views
Path planning priors in dynamic enviroments
What are the general path priors used when planning in a dynamic environment with people/cars/other robots?
Suppose you don't have a global view of the environment, only a local view around the ...
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0answers
24 views
calculate self aligning torque from steering wheel angle
I would like to calculate self aligning torque (SAT) to apply it for a simulating game with Logitech G29 steering wheel, the torque is gonna be inferred from steering wheel angle (plus car motion). I ...
0
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1answer
98 views
Matlab Simulation using Webots!
I am trying to run this youbot ( sample world) from webots, where the controller is implemented in MATLAB, on running the code it pops out the following error seen in the picture attached. I have also ...
1
vote
1answer
46 views
Odometry using wheel encoder with no differential drive
I am currently looking for a way to do odometry using wheel encoders, for a car that has no differential drive. The two rear wheel would rotate at the exact same speed. I have been looking everywhere ...
0
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0answers
18 views
How does a recursive Bayesian depth filter is used to build a map in visual odometry?
I am trying to understand a paper on visual odometry and I am having troubles understanding how a map is generated using a stereo camera as sensor.
The paper I am reading is SVO: Semi-Direct Visual ...
1
vote
1answer
24 views
What is the purpose of an empty link without any child elements?
I was looking at a model xacro [urdf] file in a ROS tutorial when I saw:
...
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0answers
32 views
How does inverse compositional Lucas–Kanade algorithm work?
I am trying to understand the Lucas–Kanade algorithm since I am reading a paper in which is applied the inverse compositional Lucas–Kanade algorithm, but in order to understand the latter I have to ...
2
votes
1answer
71 views
How to PID tune a four wheel robot?
Four wheel mecanum rover with a mass of approximately 50 Kg. Each wheel has a 20:1 gearbox with encoder at the wheel (rather than the motor).
If this was something like a robot arm I would PID tune ...
0
votes
1answer
15 views
AC Motors vs Hydraulic motors for skid-steering robot
I'm designing a mobile robot with tracks and skid-steering driving system and I am evaluating whether an electric motor would be better than a hydraulic one.
I did some calculations, the total weight ...
1
vote
1answer
40 views
Problem understanding a paper about visual odometry
I am reading the following paper: SVO: Semi-Direct Visual Odometry for Monocular
and Multi-Camera Systems
, and I am having some problem understanding some concepts.
Before starting I have to say ...
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0answers
15 views
Use polynomials to detach number of MPC controls from size of time-horizon?
Model Predictive Control (MPC) works by finding a set of controls $u_0, \dots, u_n$ that minimize a cost function $J$ over a time-horizon $[t, t + T]$. Typically when MPC is used on mobile robots, ...
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vote
2answers
62 views
motion model for forward movement
I thought this is a simple and well known problem and therefore there is a lot of literature. But I'm not able to find the correct keywords to google the answer. Maybe instead of answering the whole ...
1
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1answer
70 views
Applications of Reinforcement Learning
Many global-control applications of robotics involve incomplete world information and at best can be represented as a POMDP.
Given this, can we really apply RL to most robotics applications? From ...
