28 votes
Accepted

What is the difference between path planning and motion planning?

Compare the following two images: The path planning is somewhat trivial. There's only one path: the rope. The motion planning on the other hand is not that easy. In a maze the path planning is hard ...
10 votes
Accepted

How to program a three wheel Omni?

The math involved for controlling a holonomic robot is really not too bad. It is basically just high-school trigonometry and knowing how to set up the problem. First, lets start with the joystick. ...
  • 5,455
10 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 ...
  • 2,709
8 votes

Seeking dirt cheap, wheeled, programmable robot

Did you say dirt? May I recommend a Roomba? It has wheels and tracks. A cat wouldn't be able to flip it over. It already knows how to move randomly around a room, turning at walls. It already makes ...
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 ...
  • 5,455
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....
  • 4,255
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 ...
  • 1,009
7 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 ...
  • 106
6 votes
Accepted

Which micro-controler/processor to be used for autonomous stereo vision robot system?

Stereo vision and SLAM are pretty heavy algorithms, both in terms of the processing power and RAM required. You can forget about running this on a little microcontroller like an Arduino. These run at ...
  • 6,337
6 votes

What is the maximum payload weight for create 2/can I use old create accessories with the Create 2?

Assuming that you keep the payload in the bin or near the top of the robot, 9 kg is a safe amount of max payload weight on a flat floor. Create doesn't dynamically balance, so having the weight in ...
  • 952
6 votes

What is the difference between path planning and motion planning?

What's the difference between turn-by-turn GPS and driving a car? GPS is path planning: high-level commands like, "turn right in 1 mile." Driving is motion planning, which means following a route ...
  • 15k
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 ...
  • 963
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 ...
  • 1,238
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 ...
  • 15k
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 ...
  • 15k
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 ...
6 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 ...
  • 1,337
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.
  • 477
5 votes

What is the technical name when robot wheels are aligned to perform spot turn?

Looks like wikipedia calls it Active Four-Wheel Steering. Although, what you're talking about is the left and right side steering opposite of each, whereas Active Four-Wheel Steering in automobile ...
  • 306
5 votes
Accepted

Seeking dirt cheap, wheeled, programmable robot

You haven't define what's the limit of your budget. However, for cheap programmable robots you can use: the DFRobot 2WD Mobile Platform and interface it with an Arduino Uno. You can also use a Pololu ...
5 votes
Accepted

Cheap and efficient 3D sensor?

Honestly it depends what you want, I will cover some options from cheapest to most expensive Ultrasonic sensor on a servo 5-50$ depending on the model. It can be fairly accurate with around 1cm ...
  • 1,909
5 votes

image processing

Ball detection using vision is not extremely difficult, especially if the ball is easy to recognize. There are a lot of tutorials and blogs which give a detailed explanation on how to implement an ...
  • 260
5 votes
Accepted

Is modelling a robot and deriving its Equations of Motions more applicable to a system that is inherently unstable?

A system is (marginally) stable if all of the poles are (equal to or) less than zero. In general, the poles of a system determine whether a system is stable or not, and the zeros of a system determine ...
  • 15k
5 votes
Accepted

Humanoid balancing

Keep in mind that the ZMP is a simplification. In practice with walking robots the support polygon is constantly changing so it can be tough to keep the ZMP inside. Pregenerated (offline) ...
  • 4,255
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 ...
  • 15k
5 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 ...
  • 960
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 ...
  • 1,823
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. $H_2$ ...
  • 2,709
4 votes
Accepted

What is the technical name when robot wheels are aligned to perform spot turn?

I'm not aware of any technical name for the alignment of the wheels except -- literally -- "steering". Spot turns in theory are no different than any other turn. You simply align the axis of each ...
  • 10.9k
4 votes

Seeking dirt cheap, wheeled, programmable robot

Dirty cheap robot: Try seeking in Aliexpress/Ebay/your local e-store something called 2WD robot chassis. For about ~14-16 usd you will get two wheels and two engines and quite good basic platform ...

Only top scored, non community-wiki answers of a minimum length are eligible