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6 votes

Inverting a transform (Reading J Craig's book on Robotics)

Given that an homogeneous transformation $T \in SE\left(3\right)$ can be expressed as $$ T= \left( \begin{matrix} \mathbf{R} & \mathbf{p} \\ 0 & 1\end{matrix} \right), $$ where $\mathbf{R} \in ...
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5 votes
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Cartesian Impedance control Damping Design (Double Diagonalization)

A hint towards what the answer is given in the paper. Namely, one can use the generalized eigenvalue decomposition, which in this case can be formulated as finding eigenvalues $\lambda \in \mathbb{R}$ ...
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5 votes
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role of chi2 in SLAM back-end optimization

Specifically, the Chi-Square Distribution(or Chi2, $\chi^2$, or equivalently $\chi^2_1$) is used to model the probability of the absolute value of the deviation of the measurement from it's expected ...
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4 votes
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Why models are not perfect to represent robotic environments?

A model of the environment in this context is an abstraction of the real world, which should be adequate for the task of the robot. For example, if you have a robot that needs to navigate an office ...
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  • 2,954
4 votes

What is the difference between screw and wrench in rigid body motion?

I will try to make it as simple as possible. Imagine you have a SCREW, when you WRENCH it, it TWIST forward or backward. From your wiki link The components of the screw define the Plücker ...
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  • 43
3 votes
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Difference between Degrees of Freedom (DOF) and Degrees of Motion (DOM)

The way you are describing it, DOM is the number of independent dimensions in $\vec q$. DOF is the number of independent dimensions in $\vec x$. In practice, a robotics engineer will use DOF to ...
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  • 4,326
3 votes

Does a controlling system need to be more complex than the system being controlled?

Complexity is not a word that's used in control theory but I think I know what you mean. The short answer would be no. Complexity in systems to be controlled is usually looked at in terms of how many ...
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  • 4,235
3 votes

I want to be a guy of robotics

Not too long ago I was a beginner myself so please let me give you my two cents worth of advice. First of all, some background. There are different types of robots you can build and the way they ...
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3 votes
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Why Does an Exponential Make ANYTHING a Probability Distribution

I believe it's because you're essentially constructing an exponential distribution which has the form Because your loss function will always be >= 0, you form a valid PDF (valid in that it ...
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2 votes

What algorithm should I implement to program a room cleaning robot?

I'm not sure if you still need it, but for those who happened to google for this thread, I have made one simple version of the algorithm. Basically, it tries to build the map of the area while it ...
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2 votes
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Is Fuzzy logic applicable for robotics research

I would like to mention that Fuzzy logic is still an active control system used in many industry applications. In garbage fired power plants, concrete aggregate firing, hydraulics, and the control ...
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2 votes

Is Fuzzy logic applicable for robotics research

Short answer: Fuzzy logic (FL) isn't applicable for robotics research, The long answer is, that in the 1980s as part of the fifth computer generation fuzzy logic was researched in Japan with the ...
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2 votes

Is Fuzzy logic applicable for robotics research

Fuzzy logic is definitely used in many of the control systems including but not limited to robotics. See this paper for an example: https://pdfs.semanticscholar.org/b9a7/...
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2 votes
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What is exact model of haptic interface system in the paper "Time-Domain Passivity Control of Haptic Interfaces"?

It's usually best to contact the author directly if you have a specific question about a specific paper. The simulations are there only to illustrate the principal of the passivity observer and ...
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2 votes
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Angular velocity in terms of quaternions

A definition of the cross product for quaternions is $$p \times q = \frac{1}{2}(pq - qp)$$ We also have the identity (3.167) in Jazar $$pq = -p \cdot q + p \times q$$ Apparently the vectors $ \dot{...
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2 votes

What is difference between RoboEarth and KnowRob?

RoboEarth was the name of a European project. Knowrob is software that was developed, in part, by the RoboEarth project.
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  • 4,235
2 votes

Why Does an Exponential Make ANYTHING a Probability Distribution

To complement what Octopuscabbage correctly reported, there exists a strong theoretical foundation for using normal probability distributions in many different contexts, which builds on the Central ...
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1 vote
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Going from Spline to Differential Drive Command

If you have the path you want the robot to stay on, it sounds like you need Pure Pursuit. In this simple algorithm, you steer the robot to some look-ahead point on the path. The gist of it is ...
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  • 5,215
1 vote
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How is this torque value arrived?

I haven't seen the degree symbol $^{\circ}$ to denote a percentage, but both percentages on your drawing result in the same torque: 54.7, not 57. (10.12/0.185) $\approx$ (34.12/0.6238) $\approx$ 54.7. ...
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1 vote

Articulated configuration

Seems that the book has an error. You are right, they should correct that. In the drawing it can be seen that those two z-axis are indeed parallel. I recommend that you considered them parallel and ...
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  • 477
1 vote

Is Fuzzy logic applicable for robotics research

I have not seen any industry-grade application of fuzzy logic in space, flight, automotive control systems. Fuzzy logic came during mid-60s and it gradually faded away due to several reasons: It did ...
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  • 357
1 vote

Why ODE for optimal control theory?

Appending to @WalterJ's answer. Linear and nonlinear systems which form the basis for subjects like optimal control theory have rigorous math fundamentals which allow you to analyze ODEs without ...
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1 vote
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Why ODE for optimal control theory?

The reason why ODE's are used is simply: physics. It would be great if any system could be modelled by a simple linear function like $x(t)=at$, but nature is not so simple, or linear. Even when you ...
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  • 156
1 vote

Strange phase case in Bode diagram of a transfer function

It's just a phase unwrapping case in MATLAB. Anyway when real parts of complex poles/zeros are null, phase jump could be +180 or -180, it's uknown therefore both diagrams are correct
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1 vote

How many stages necessary to stabilize position while controlling torque?

If you are trying to implement torque control, you only need a control loop around torque. The challenge isn't in trying to integrate the torque (or acceleration) controller, and passing it to a ...
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  • 4,326
1 vote

How many stages necessary to stabilize position while controlling torque?

I would say the transferfunction becomes $\frac{1}{s^2}$ iff you assume you have a perfect drive without any dynamics. Since this system is unstable you have to be careful choosing your controllers. ...
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  • 189
1 vote

Papers on Algorithms in Robotics

You might like the algorithms run on PR-2 robot. Two papers I can think of are "A single planner for a composite task of approaching, opening and navigating through non-spring and spring-loaded doors" ...
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  • 11
1 vote

Which math course will be most beneficial?

I went through the Virginia Community College System (VCCS) (not saying which one specifically for myself). In Virginia, if you graduate with >= 3.0 GPA from a Virginia Community College, you are ...
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1 vote

Perfect implementation of Asimov's 3 Laws

I disagree that implementing law 1 automatically implements the other 2. Law 1 only states that a robot may not injure a human. Nothing in that law implies that the robot must obey people or protect ...
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  • 5,215
1 vote

Shortest path using wave planner?

According to this website http://www.cs.tufts.edu/comp/150IR/labs/wavefront.html It shows a method of converting the zero to number and calculating the fastest distance.I am assuming you mean ...
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