7 votes

Motion Planning vs. Control

There is a saying in software engineering which states that your company structure is reflected in your software architecture (I cannot recall the exact phrase). This is true for a robot control ...
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  • 6,437
5 votes
Accepted

Configuration space of rotating link

Since the configuration space is the set of all possible configurations the link can have, i.e. all possible angles from 0° to 360°, shouldn't the c-space be a line rather than a circle? You are ...
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5 votes

A* search results in path too close to obstacles

Obstacle padding/ robot padding. Suppose you are working in a 2D environment and that you have an obstacle of the size 2x2. When doing planning (graph search, etc.), you increase the size of the ...
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5 votes
Accepted

Why in trajectory planning in joint space the manipulator never crosses a singularity?

The term "singularity" characterizes those configurations in the joint space where the Jacobian matrix loses rank and thus it is not directly invertible. The Jacobian, in turn, is used to remap a ...
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4 votes

How can we solve the problem of robot size in sensor based motion planning?

If you are able to sense obstacles with a sensor pattern that is circular (eg laser scanner, contact sensors on a circular body, etc), and you can rotate the robot pose without translation, then you ...
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  • 4,235
4 votes
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Motion planning from a given path

Many articles reference algorithms such as A*, PRM or RRT based planners to motion planning algorithms which seems unreasonable since it is still necessary to parametrize found path with time.I wonder,...
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4 votes
Accepted

Solving a grid maze with blocked paths

You didn't specify any performance requirement. That admits the simple algorithm: ...
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  • 1,136
3 votes

Understanding MoveIt! and OMPL more deeply

Actually I wish to implement my own algorithm (like some variation of RRT) without MoveIt!/OMPL hence it is important for me to know all the details. I am really confused about this. Any ...
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3 votes

Generate a coverage path given a polygon region

This thing is generally called coverage path planning. If you are particularly interested in Boustrophedon Cell Decomposition, you may have a look at the paper introducing it: Choset and Pignon (1998)...
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3 votes

Optimal-Time Trajectory Planning in 1D

Hi usually the time optimal solution of a motion not having specific constraints is know as 'bang-bang'. Where you let you system accelerate and decelerate at the maximum rate possible. In your case, ...
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  • 1,327
3 votes
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Is MoveIt! suitable for fixed-wing aircraft path planning and obstacle avoidance?

Not really MoveIt! is designed for robotic arms, and is being heavily adapted for the applications you see here, fixed wing aircraft typically use very diffrent types of motion planning becouse of the ...
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  • 1,909
3 votes

A* search results in path too close to obstacles

Most planning algorithms reduce your robot to a point and plan a path for that point. The arising problem is exaclty what you are facing. As suggested before, obstacle padding is one of the methods, ...
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  • 6,437
3 votes

What is the difference between Obstacle Avoidance and Dynamic Path Planning?

I have lots of experience with this that I won't bother you with. Most vehicle planners have multiple layers, with different requirements. In short, you're right in that they are very closely related ...
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3 votes

Representation of 2D coordinate space with orientation

You need to resort to the Special Euclidean groups. In particular, in your planar case, the group is $SE\left(2\right)$ and thus the representation is the following: $ T=\left(\begin{matrix} R & ...
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3 votes

Iterative calculation of trajectory

Trapezoidal trajectory is basically a piecewise quadratic function. Since the function is quadratic, its second derivative is a constant. The trajectory is then basically comprises segments of ...
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3 votes

What Software Is Used For Autonomy Software Simulation?

There are quite a lot options for this, each with different features, strengths and weaknesses. A few examples: Gazebo (as mentioned by edwinem): very well known in the robotics community, some would ...
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  • 131
3 votes

Applications of Reinforcement Learning

It's true that using RL in robotics involves many challenges, including the usually high dimensionality of problem spaces, the cost and limitations of real-world sessions, the impossibility or ...
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  • 1,266
2 votes
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How to Visualize a real robot's movements on a map?

There seems to be two questions in one: How should I visualise the trajectory (planned and traversed paths)? How should I combine "ultrasonic sensors, infrared sensors, camera, human sensors etc. " ...
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2 votes

How to compute a path from a Frame A to a Frame B

Quaternions and SLERP is what you want.
2 votes
Accepted

Robotic vessel navigation using GIS datasets

If I understand your question correctly, you are trying to estimate the position of arbitrary points in an environment given scattered 3D points. For example, your robot is at position (x, y, z) where ...
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  • 561
2 votes

How often does a robot perform A* (A star) path planning in an unknown map?

There is a dynamic version of A* (or of Dijkstra's algorithm) that was developed to address exactly this problem of trying to do planning on a map as you discover it. It is called D* or occasionally ...
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  • 324
2 votes

Can the A* Algorithm be implemented on an Arduino easily?

You're welcome to steal the AStar class from my C++ highway driving project. https://github.com/ericlavigne/CarND-Path-Planning I used AStar to control a car driving on a simulated highway with ...
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2 votes
Accepted

VFH (Vector Field Histogram+): Obtaining the Primary Polar Histogram

I have found out that my code works. It is just that most of the literature I have read uses Lidar or Sonar sensors for histogram updates. I had assumed that in the case of a stereo vision set-up, all ...
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2 votes

How to calculate shortest path between multiple pick and drop destinations

Side note: If there are multiple objects at A and C, so the robots continue circulating to move the objects cyclically, then ABCD and CDAB are the same paths. In either case (single objects at A ...
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  • 4,326
2 votes

Difference between Single-Query and Multiple Query Algorithms?

I think what you said in your question is correct so far. Single and multi query planning refers to the number of planning tasks you are about to execute. That means, the number of different paths ...
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2 votes
Accepted

Is there a Java or mathematical algorithm for Pure Path Pursuit?

In words, rather than code. Assume you have the path defined as a dense list of points. Find the point on the path closest to robot Draw a circle of radius R about that point, then find the point on ...
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  • 1,522
2 votes

What is Natural Navigation?

What they describe is normally called (markerless) SLAM. Mostly implemented with laser scanners (from Sick, Velodyne, Pepperl&Fuchs,...). Classic implementations are gmapping, cartographer or ...
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  • 1,335
2 votes
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Potential field algorithm implementation

I am assuming you need a force field mapping of a two-dimensional space. You will need an array to hold the goals, unless there is only one. You will need an array to hold the obstacles. Both of ...
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  • 4,326
2 votes

How does it get a bizarre term in triangle law of vector equation in a paper

You made a simple mistake while calculating the derivative.The equation is: $\vec{OP}= OP_s \vec {i_s} + P_sP \vec {j_s}$ The derivative should be $\partial \vec{OP}/ \partial t =\partial({OP_s}\vec ...
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  • 191

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