Questions tagged [mobile-robot]
A robot which is capable of moving from one place to another, usually of its own volition.
638
questions
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1answer
32 views
URDF for a real robot
I have been making robots in ROS/Gazebo simulation before, which makes use of the URDF to understand the robot model, different frames and transformations. For a real robot, do I need a URDF as well? ...
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25 views
What hardware to choose for very simple computer-vision, map building and motion planning? [closed]
I want to build a small robot to detect paper edges on which it is located while moving, to get its size (a4, a5 etc), build its map and plan the path. Ideally paper could be any color, shape and size,...
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24 views
Differential Drive Control Techniques
I have a mobile robot that has a differential drive technique. I try to control the robot with PID controller. Is the best way for controlling differential drive robots?
If I want to compare different ...
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27 views
Add a repulsive force among a group of robots
I am new to multi-agent robotic systems and I am currently studying consensus and flocking algorithm.
Recently I implemented a simple integrator consensus algorithm that leads a group of N robots to a ...
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16 views
how can i drive the linear state space model of this ackerman steering model
i have an ackerman steering model like so :
...
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1answer
20 views
Move a Three Wheel Omni Robot
I understand this isn't for programming but it's easy to read. I have referenced This for a guide on how to move a 3 wheel omni robot but I have encountered a few problems.
...
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1answer
37 views
Choose the structure of the dynamic model for the generalized equations of motion of the robot
I ask the robotics specialists for help as I am a little confused.
I have two subsystems which are shown in the picture below:
One of them is a system of stable and controlled differential equations ...
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0answers
25 views
torque calculation issues
so i have been trying to draw a free body diagram of a 6 axis robot arm project, in order to know the torque required for each joint. and now am confused about the angular acceleration part which ...
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1answer
36 views
Mobile robotic arm camera position
I'm working on my graduation project which is a mobile robotic arm that performs pick and place tasks.
I wanted to know the possible ways to mount the camera where i can reach the desired destination ...
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1answer
91 views
4-Wheeled Mobile Robot, Motor-Torque, RPM Calculation
I want the torque, rpm of every motor to be used considering certain factors, in a 4 wheeled robot as you see in the picture below.
Here are the factors affecting motor specifications that I Had ...
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1answer
46 views
What is the most cost effective yet still reliable outdoor boundary system?
I am working on a robot that will operate outside in people's lawns in a predefined space. The issue that I am having right now is figuring out what kind of boundary system I should implement in order ...
0
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1answer
26 views
Dynamically-stable Motion Planning for Humanoid Robots
I was reading the classical robotics paper Dynamically-stable Motion Planning for Humanoid Robots and I don't understand why the two trees are swapped in line 7 of figure 5 (page 11). Seems like an ...
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22 views
Quasi Direct Drive Actuator - Slot & Pole Combinations for High Torque Motor
I am building my own Quasi Direct Drive actuator and looking for information/ design guidelines for building a High Torque Motor similar to the MIT Mini Cheetah below. Specifically I cannot seem to ...
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1answer
49 views
Drive unicycle kinematics equations through the geometry
The unicycle dynamics in discrete-time is given by:
$$
\begin{array}{l}
{x_{k + 1}} = {x_k} + \Delta {s_{k + 1}} \times \cos ({\theta _{k + 1}})\\
{x_{k + 1}} = {x_k} + \Delta {s_{k + 1}} \times \sin (...
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1answer
51 views
Does full motor current pass through 'switches' on children's driving vehicles?
I plan to hijack a powerwheels-like toy to control it with the jetson nano. Here is the toy:
https://www.wayfair.com/outdoor/pdp/konbeca-ride-on-bumper-car-kids-toy-electric-funny-ride-on-car-for-360-...
3
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1answer
36 views
Do diagonal mecanum wheels require the rollers to cross the center of the robot
I'm currently in the process of making some changes to my robot to use mecanum wheels. The kinematic models I've seen assume the 45 degree roller from one diagonal wheel to the other, crosses the ...
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2answers
91 views
Some doubts regarding SLAM and its technical terms
I have some questions regarding SLAM and some general technical terms used in the context of it.
Q1) **Online SLAM vs Offline SLAM**. Can "Online" SLAM be also called "real-time" SLAM? What is the ...
0
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1answer
25 views
Count number of collisions while navigating to goal
I have the navigation stack working in ROS Kinetic on my computer. In Stage ROS simulations, I can specify the goal and the robot navigates to it. I need to count the number of collisions (if any) ...
3
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1answer
113 views
Calculate information matrix for graph slam
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I am new to SLAM. I am working on graph slam where I need to do pose graph optimisation. For this requirement information matrix is required between two edges for which the transformation has ...
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2answers
52 views
Reinforcement Learning in global and local path planning for mobile robots and self-driving car
Most RL courses start with grid world problem like this where robot has to navigate from start to end and RL helps in generating the optimum policy. (State-action pairing).
I am not able to relate ...
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0answers
39 views
Can a state lattice planner be used purely as a local planner?
I've been reading a bit about state lattice motion planning recently. The question I would like to ask is if a lattice-based motion planning system can be used purely as a local planner without a ...
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0answers
15 views
Why reciprocal velocity obstacle generates oscillation free navigation compared to VO
I am tryin to understand this paper about "reciprocal velocity obstacles for real-time multi-agent navigation" and to compare it with the original Velocity Obstacle approach.
I can not ...
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1answer
61 views
How to design a PID controller for boat?
I have a boat with two trusters and a trajectory planner which is based on the bicycle model. In order to control the boat, the linear velocity of each truster has to be provided.
The following ...
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1answer
70 views
Calculating wheel linear velocity from body velocity
A frame {b} is attached to the centre of a robot chassis. The planar configuration is given by $(x,y,\phi)$ where $\phi$ is the angle between the x axis in {b} and the x axis of a fixed reference ...
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1answer
66 views
Small AGV robot for ROS application
I am looking for an off-the-shelf small AGV which runs or could be used with ROS. It may include some basic sensors like a camera, an IMU, an Ultrasonic range finder, etc.
Really appreciate all the ...
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1answer
44 views
Autonomous harvesting robots. What are model possible components and interactions for the entire system? [closed]
I found a video which talk about best autonomous robots that use IA technology to harvest crops. The video is very interesting because, the “ecosystem” of each robot varies a lot from company to ...
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1answer
144 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
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1answer
56 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
35 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?
...
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1answer
52 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 ...
3
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1answer
151 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/...
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1answer
120 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 ...
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0answers
78 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 ...
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0answers
23 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 ...
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0answers
32 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 ...
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0answers
20 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
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1answer
94 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, ...
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0answers
25 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 ...
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0answers
32 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
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1answer
47 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 ...
1
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2answers
58 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 ...
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0answers
50 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 ...
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0answers
20 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
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2answers
30 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
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1answer
29 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 ...
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1answer
43 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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1answer
43 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
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1answer
64 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
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1answer
81 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
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1answer
48 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. ...
