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Position Control vs Velocity Control vs Torque Control

I'm going to take a slightly different tack to Chuck. What is Torque Control? For me, Torque Control is about performing a move with an explicitly defined torque, rather considering torque just the ...
Mark Booth's user avatar
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16 votes

Position Control vs Velocity Control vs Torque Control

Torque is analogous to force for rotating systems, in that: $$ F = m a \\ \tau = I \alpha \\ $$ Where $\alpha$ is angular acceleration and $I$ is moment of inertia. $m$ and $a$ are mass and linear ...
Chuck's user avatar
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11 votes
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Control VS artificial intelligence?

In robotics, it all boils down to making the hardware(in essence, the actuator) perform the desired action. The basics of control systems tell us that the transfer function decides the relationship ...
Akshay Kumar's user avatar
10 votes
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How to create a Industrial Robotic arm controller?

Industrial robots (e.g. Kuka, ABB, Fanuc) use a control cabinet which has the following main components: Drive amplifiers (controllers): The drive amplifiers are responsible for the closed loop ...
50k4's user avatar
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10 votes
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Impedance Control vs Position Control

In classical position control, the feedback controller only cares about the position error and is tuned to minimize it. This is done by using very high gains, i.e. if there is even a small position ...
Kapt. Brackbier's user avatar
10 votes
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What is the terminology used to describe control without measurement?

In control theory, we refer to this as "open-loop control", which emphasizes the lack of a feedback loop. The wikipedia article has several examples of open-loop control.
Mitchell Allain's user avatar
9 votes
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How to tune the PID parameters using Fuzzy Logic?

The paper Controlling of Quadrotor UAV Using a Fuzzy System for Tuning the PID Gains in Hovering Mode by E. Abbasi, M. J. Mahjoob explains how to tune PID gains with fuzzy logic. You can find many ...
acs's user avatar
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9 votes
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How do I determine the required encoder resolution for a control system?

First I would question your math that got you to the 12b sensor. If you have a $dy$ of 1 mm over an arm that is $r = 1$ m long, then $\sin(\theta) = dy/r \rightarrow \theta = \mbox{asin}(dy/r)$. If ...
Chuck's user avatar
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9 votes
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How to approach any advanced control problem in robotics

Models. If you want to get good at control engineering, get good at modeling. If you want to impress a controls professor, get good at modeling. Models are how you're going to do 90 percent of your ...
Chuck's user avatar
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8 votes
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Can a state matrix have a row of zeros?

Yes, a state matrix with zero rows and/or columns makes sense and is viable. It typically signify pure integrators in the system. In the example you give, $$ \dot{v} = -\frac{b}{m} v +\frac{1}{m} u ...
Christo's user avatar
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8 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 ...
50k4's user avatar
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8 votes
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Cartesian Velocity Control between Two 3D Poses

You essentially want to find the time derivative of a linear interpolation between two rotations. The easiest way to obtain this would probably to convert the rotation matrix between the two ...
fibonatic's user avatar
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7 votes

Explanation of Quadcopter Dynamics, Components and Control

A couple things, the first is that the controller does not really care what the "real" values are. Everything is relative, if the controller sees that it is sinking it will increase the thrust until ...
Mark Omo's user avatar
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7 votes
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PID control: zero out integral on error sign change?

Generally, in a well-tuned PID, most of the job is done by the P term, which is responsible for driving PV to SP. Then, D and I serve as corrections: the D term regulates the profile as of how we ...
Ugo Pattacini's user avatar
7 votes

Control VS artificial intelligence?

I think, it is easier to explain these areas in terms of guidance, navigation and control layers for an autonomous robot. Let's stay an autonomous robot is commanded to reach a desired goal position ...
Octavius's user avatar
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6 votes
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How can I apply different control approach without having a state space model?

Many control strategegies (PID is not neceserily one of these) are computing some of their parameters from your system. If you do not want to model your system yourself (or play around with it until ...
50k4's user avatar
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6 votes
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Extended Kalman Filter in robotics - Worth it?

The Kalman filter is an optimal linear filter in the presence of Gaussian noise. It is optimal in the sense that it minimizes the mean-squared error. This means that the covariance of the estimated ...
Parker Lusk's user avatar
6 votes
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PID and Kalman filters

There isn't really a relationship between them, unless you're asking how the dynamics feed each other when combined into a system. If that's the case, then I would suggest maybe starting with a ...
Chuck's user avatar
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6 votes
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What is a Velocity Smoother?

The velocity smoother part of the code is this: ...
50k4's user avatar
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5 votes

How to further understand the computed torque model controller

One of the most common controllers is a computed-torque controller, also known as the inverse dynamics. The preceding controller is based on the feedback linearization principle which is an approach ...
CroCo's user avatar
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5 votes
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Why is it so hard to walk?

I'm not sure I agree that bipedal walking is so much harder that airplane control. It depends on how you look at it. Many robots can walk (bipedal walking) and many airplanes are difficult to control ...
hauptmech's user avatar
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5 votes

How has the Mars Exploration Rover (MER) has been working for 11 years if it was designed for 90 Sol?

There are 2 main reasons why the MER is still operating long after it's 90 Sol planned lifetime. The first is political, strategic, and can be summarized as 'Under promise, over deliver'. When a PI (...
hauptmech's user avatar
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5 votes
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Why to combine a Raspberry Pi (or similar board computer) and an Arduino for controlling motors?

The reason is Clock on the Raspberry Pi. Note that the raspberry is powerful but not that powerful that it can run an OS and simultaneously give you precisely timed PWM outputs. I assume that you'll ...
Kartik Madhira's user avatar
5 votes
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What's wrong in controlling Roll+Roll rate in a quad-copter instead of using 2 separate loops for each?

That only works when the desire roll angle is 0. What happens if you are trying to turn and have a desired roll angle of 1deg? Even changing your sum to match the angle error, $w_1 (\theta - \theta_d) ...
ryan0270's user avatar
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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
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5 votes
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Meaning of a negative step response with quaternion

Welcome to Robotics, PaoloH! This is a fantastic question for Robotics - It has some Matlab/Simulink, some control theory, some spatial (quaternion) representations, etc. Robotics is the place to come ...
Chuck's user avatar
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5 votes

Struggling to understand Jacobian Inverse Kinematics

You will find it helpful to keep the physical robot and the math separate. The kinematics equations map joint parameters (which are often grouped as a vector $q$) to Cartesian coordinates ($x$,$y$,$z$...
hauptmech's user avatar
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5 votes

State Space model for bouncing ball

Matrix notation in general is nice because of how compactly you're able to write and especially read everything, similar to using descriptive variable names in programming or performing algebra with ...
Chuck's user avatar
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5 votes
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Why is the Kalman filter a filter and not a control system?

A Kalman Filter (estimator is actually more apt than filter) simply estimates states, that's all it does. It, by itself, cannot drive a plant towards a desired output. The estimated states are used to ...
abhishek47's user avatar

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