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1500 questions
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votes
2 answers

Zero crossing events with brushless DC motors

I would like to ask a question about zero crossing event in a trapezoidal commutation on a brush-less DC motor. Here is a waveform that shows that the zero crossing event occurs every 180 electrical degrees in a sinusoidal commutation: But what…
natal1452
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FABRIK Inverse Kinematics Convergence Proof For Multiple End-Effector Case

Below, I've linked the FABRIK papers, the first of which is particularly relevant to my question, as it shows the convergence proof for the single end effector case, and this makes sense to me. But I have trouble extending the proof and proving…
Wasiim Ouro-sama
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1 answer

Why does ROS2 claim to be "real time"?

ROS2 uses DDS, in the wiki it says that DDS is "The Data Distribution Service (DDS) for real-time systems is an Object Management Group (OMG) machine-to-machine (sometimes called middleware or connectivity framework)" The question is, how can a…
Ricardo Casimiro
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2 answers

I am an entrepreneur and I want to start building robots for businesses, where do I start?

Over the last couple of years I've had good success with my technology startups and now looking to enter into robotics. I was interested in robotics and automation ever since I was a kid (yes, that sounds nerdy). So my question is: Where to get…
Tracy
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1 answer

Compute Maximum End Effector Velocity Along Path

Let's say I have a 2-link planar robot arm. The motors in both joints have maximum angular speeds that limit how fast they can spin. If I plan a path from point A to point B with a constant end effector velocity, how do I calculate the maximum…
Jacob G
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1 answer

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/coulter_r_craig_1992_1.pdf Such that the steering…
Luke H
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4 answers

Robots without microcontrolers (beam robots). Are they technologically limited?

BEAM robotics seem to be a good approach to teach learners about electronics in robotics. But can these robots be like regular programmed "cognitive" robots? Can these robots, with just analog circuits, take us to the level of robotic assistants,…
xsnk
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1 answer

Forward kinematics confusing point

I am studying robot arm kinematics. In order to construct a transformation from a global coordinate frame to the end effector frame, I have seen references to the Denavit–Hartenberg (DH) convention. In this convention, a single operator is…
user28267
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1 answer

Torque required to rotate arm with mass at end

I have to calculate the required torque to rotate a point mass of 15N on the end of an 1.2m long arm which I have calculated to be 10kg in mass. The rotation must have a constant angular velocity of 50rad/s. I am just wondering how to calculate the…
James Briody
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3
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2 answers

Inner current controller benefits

I am currently working on a system with a BLDC motor attached to a non linear spring on which a user can apply a force. Meaning the torque applied on the motor's output is most of the time unknown. What matters for my application currently is the…
Robs_vic
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1 answer

Difference between Denavit-Hartenberg and Rodrigues formulas/conventions

I am trying to compute the forward kinematics for a 6 DOF robot arm. I've found two methods : the Denavit-Hartenberg (original and modified) and the product of exponentials with the Rodrigues formula. But I did not found any paper on the advantages…
hugosc
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1 answer

Calculating rotation matrix efficiently

I'm trying to efficiently calculate the vertical offset of each corner of a rectangular base. I have an accelerometer mounted in the middle of the base, ADXL345. The steps I have taken, and seems to work are below. Can anyone advise if this is the…
Slicc
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3
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1 answer

Looking for resources regarding conveyor object allignment / object orientation

Im currently on the hunt for resources / examples / words to use in a search engine in regards to orienting (aligning, funneling) an object on a conveyor. I am looking for techniques / utilities used to 'line up' an object on a standard belt…
Kevin Crum
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3
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1 answer

Does it matter how I mount an IMU board?

I am going through the board's calibration process and it is declaring success. Do I still need to pay attention to how I mount the board, that is, match the x,y,z directions printed on the board?
pitosalas
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3
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1 answer

What is the difference between a Bayes Net and a Factor Graph

I am just getting started on understanding Factor Graphs, by going through the excellent guide Factor Graph For Robot Perception by Dallaert and Kaess While I am familiar with the SLAM problem, and have a fair understanding of the probability and…
OlorinIstari
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