11 votes

What is the difference between a holonomic and an omnidirectional robot?

Holonomic is a precise mathematical term; one definition is velocity constraints can be integrated into the form $$\begin{align} f(q1,q2,...,t) = 0. \end{align}$$ Roughly, that means the ...
ryan0270's user avatar
  • 2,804
9 votes
Accepted

How exactly does sensor fusion work in Kalman filters?

I realize this question already has an accepted answer, but I'd like to provide some additional input. The question of sensor fusion is a good one, but, depending on the application, you don't ...
user96966's user avatar
  • 126
8 votes

Alternative to ROS?

I think you are getting confused between the basic ROS possibilities and some more advanced libraries which are integrated but do not need to be used by users without 'advanced' requirements. If you ...
N. Staub's user avatar
  • 1,412
7 votes
Accepted

Finding Center of Mass for Humanoid Robot

Yes. As @hauptmech mentioned, you can use your forward kinematics to get the center of mass of each link in the base frame. Then you can simply compute the weighted average of the masses and ...
Ben's user avatar
  • 5,855
7 votes

Motor Choice given size constraint and load requirement

If you have some budget for your project, both Maxon and Faulhaber have good DC motors and motor-gearhead combinations. Maxon publishes a nice set of formulas and background theory on electric motors....
hauptmech's user avatar
  • 4,415
7 votes
Accepted

How many robots is considered to be a robotic swarm not a group of robots?

A robot swarm is defined by its behaviour, rather than the number of robots it contains. Swarm robots: "... are coordinated in a distributed and decentralised way" [Iñaki Navarro and Fernando ...
sempaiscuba's user avatar
  • 1,064
6 votes

Understanding Drift in Simultaneous Localization and Mapping (SLAM)

Your intuition is mostly correct. Returning to where you started and re-observing landmarks you mapped earlier is called closing the loop in the SLAM literature. As you mentioned, your uncertainty ...
kamek's user avatar
  • 990
6 votes
Accepted

Why would a drone need a magnetometer? Are an accelerometer and a gyroscope not sufficient?

The main difference between accelerometer and gyroscope vs magnetometer is that first two give only relative information - you may calculate heading relative to your starting position, but you won't ...
mactro's user avatar
  • 953
6 votes
Accepted

Stabilising an inverted pendulum

There are lots of ways to solve this problem, which falls into the category of Control Engineering. There are two standard approaches: Classical Control: The control command has to be proportional ...
Paul's user avatar
  • 1,268
6 votes

Motor Choice given size constraint and load requirement

20kg is a mass. It makes a force on Earth (20*9.81 = 196N), but that's not a torque. Motors make torque - what is your maximum torque specification? Once you know how much torque you need (that will ...
Chuck's user avatar
  • 16k
6 votes

Is there any robot stability control equation that describes the relation between velocity of the robot and its orientation?

That's not obvious. If I'm in a tank, going 0.5 km/h, I don't need to slow down at all. If I'm in a bobsled going 100km/h and the track banks, I don't need to slow down at all. When you steer, you ...
Chuck's user avatar
  • 16k
6 votes
Accepted

How to measure pull force on a (kite) rope?

The component you highlighted is called a tensile load cell. You could buy one from a supplier, but it probably would be cheaper to buy a cheap digital hanging scale and taking the sensor out of it - ...
Pete Kirkham's user avatar
6 votes

Which is a good and cheap 3D LIDAR or other options?

There are now some sub and around ~1000USD 3D Lidars available. I wanted to provide an answer for future reference if anyone else comes looking for "cheap" Lidars. LeddarTech M16 ~500 USD ...
Andreas Klintberg's user avatar
6 votes

What's the difference between Pose Measurement and Position Measurement?

what you are looking for is written in the paper. Position refers only to x,y,z translational measurements while pose means position and orientation.
jdios's user avatar
  • 497
5 votes

How to align solidworks global origin with assembly origin while exporting in solidworks to urdf

I did a little step-by-step tutorial with images, but if my other answer regarding aligning frames didn't work well for you, or the definition of "Front Plane" or "Top Plane" is confusing in ...
Chuck's user avatar
  • 16k
5 votes

Best sensor to determine "up" versus "down"

if you aren't moving, the accelerometer will give you the direction of gravity. if you are moving and hoping to use this orientation data for control you'll need to incorporate at least one more ...
holmeski's user avatar
  • 1,853
5 votes

Biped Robot not getting on one foot

You got the second picture by physically manipulating the robot to get the center of mass above the rotated foot. What you need to do is to get the robot to shift its own center of mass in a similar ...
Chuck's user avatar
  • 16k
5 votes

What's the diffrence between $H_2$ and $H_\infty$ control?

In short answer: yes Kalman filter is a special case of an $H_2$ observer Yes Yes ... LQG is just Kalman filter + LQR controller, which are both special cases of $H_2$ Depends on the use case. $H_2$ ...
ryan0270's user avatar
  • 2,804
5 votes
Accepted

In SLAM loop closure, What does a sim3 matrix do?

Sim3 is just the lie group associated a similarity transform which is the exact same thing as your 3D Affine transform. If you work out the multiplication for your two matrices you would find that ...
edwinem's user avatar
  • 1,861
4 votes
Accepted

Weird magnetometer values

Apparently a magnetometer is useless in indoor environments like man made buildings. I cite from this paper Multi-Magnetometer Based Perturbation Mitigation for Indoor Orientation Estimation ...
Mehdi's user avatar
  • 681
4 votes
Accepted

Best power solution for my robot

I agree with @Greenonline 's recommendation regarding LiPo batteries along with his warnings on battery care. It seems you will need a fairly small battery, considering your current requirements (...
George ZP's user avatar
  • 550
4 votes

Computer stereo vision simulator

I highly advise against using synthetic image data for testing your stereo vision algorithms. What will happen is that you end up with a system that works excellent on your synthetic data, but poorly ...
Konstantin's user avatar
4 votes

Relationship between motor torque and acceleration

1) but the more torque, the faster the robot's acceleration: YES $$ F=\frac{Torque}{wheelradius} $$ and robot's acceleration is $$ a=\frac{F}{m} $$ so, from that equation you can see that linear ...
galtor's user avatar
  • 470
4 votes
Accepted

Relationship between motor torque and acceleration

Based on the calculations, it seems that any amount of torque can get the robot moving That is true only for a theoretical robot moving in vacuum without any friction in its mechanisms. Normally if ...
mactro's user avatar
  • 953
4 votes
Accepted

Meaning of symbol, 'curly N' in the equation of Linear Gaussian system dynamics

They are modeling the probability as a normal distribution with the given mean and variance.
SteveO's user avatar
  • 4,386
4 votes
Accepted

Regarding Kalman filter and estimating heading with magnetic compass

I encountered this problem myself when making an extended Kalman filter for a quadrotor. You have to check if the estimate goes above or below +/- pi, and then correct it if it does. You can do this ...
trudesagen's user avatar
4 votes
Accepted

How to know the payload of the chassis from its motors?

If I told you my truck has 200 horsepower, could you tell me the cargo weight capacity? Not really. There are more factors than just the motor specs that play into your assessment. You might be ...
SteveO's user avatar
  • 4,386
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 ...
hauptmech's user avatar
  • 4,415
4 votes

How does fast slam creates grid maps?

Grid based FastSlam relies on the same principle that Landmakr based FastSlam. The difference is that we are not working with each grid cell as a landmark, but the whole gridmap itself. For Grid ...
Guille Sanchez's user avatar
4 votes
Accepted

Biped Robot not getting on one foot

You might be able to use the the opposite foot to begin the rotation of your chassis, but it will be dependent on your chassis and foot geometry. Using your photos for reference, the left foot would ...
kaliatech's user avatar
  • 562

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