Questions tagged [theory]

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Modelling/Theory for Quadraped Robot Leg Example

I have been working on attempting to replicate the following robot developed by some MIT graduates. https://dspace.mit.edu/handle/1721.1/98948 Presently, I am trying to work out the model for a single ...
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Park and Lynch $F = ma$ derivation for a single rigid body

I'm having some conceptual difficulties with a derivation presented in the Modern Robotics text by Park and Lynch. Here are the relevant parts: At the beginning of the book, they insist that ${\it ...
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Hi everybody! I would appreciate some help with this DH convention application. It involves a slider-crank mechanism and I'm not sure I did it right

Okay, I'm editing the post and adding some clarifications: I'm considering the slider-crank now as a closed kinematic chain, and for this reason I isolated two different branches. My attempt with the ...
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Retrieving Denavit-Hartenberg-Parameters from homogenous transformation-matrix

i am trying to implement a matlab script where the user can enter quaternions and retrieve the corresponding denavit hartenberg parameters for this link. My approach is to create the homogenous ...
3 votes
3 answers
129 views

Why Does an Exponential Make ANYTHING a Probability Distribution

I am posting this here because my background in estimation theory and optimization has been developed entirely through my experience in robotics. TLDR: What makes it so that any time you put something ...
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1 answer
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Cartesian Impedance control Damping Design (Double Diagonalization)

In the literature, it is often seen that for a system: \begin{align} \Lambda \ddot{e} + D_d \dot{e} + K_d e = F_{ext} \end{align} A dynamic damping matrix is required for a robot to take ...
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How can I modeling a simple haptic interface system to obtain results similar to the paper “Time-Domain Passivity Control of Haptic Interfaces”?

I am trying to simulate the experiments in the paper "Time-Domain Passivity Control of Haptic Interfaces", Hanaford and Ryu, 2002, IEEE transactions on robotics and automation vol .18, No1 about the ...
1 vote
0 answers
35 views

What is canonical grasp?

What is a canonical grasp and how is it different from normal/other grasp? I've searched through internet and forums but haven't found any answers.
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1 answer
210 views

Going from Spline to Differential Drive Command

I have a differential drive robot that needs to move along a path stored in its memory as a spline. I am currently trying to understand the mathematics of determining how much power to apply to each ...
1 vote
1 answer
43 views

How is this torque value arrived?

I'm going through this person's torque calculation of a simple crane setup. the servo used has a max torque of 57oz.in: At the top, if Mservo is 34.12oz.in, how is ...
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1 vote
2 answers
174 views

Angular velocity in terms of quaternions

Im reading Theory of Applied Robotics, 2nd edition by Jazar, specifically section 7.1, example 207 on page 390. The author is trying to express angular velocity by unit quaternions. Starting from ...
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1 vote
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Moment of Inertia of a planar rotation link with a 6-DOF base

I'm interested in analytic calculation of a moment of inertia of a robot's arm in the following situation. Let us assume the following: Stationary reference frame $ \{b\} = \{X_B, Y_B, Z_B\}$ and ...
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1 answer
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Articulated configuration

I'm reading Theory of Applied Robotics, 2nd edition by Jazar. The author states that articulated configuration has the following form: $R \vdash R \perp R$ where $R$ stands for revolute joint, $\vdash$...
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4 answers
176 views

Is Fuzzy logic applicable for robotics research

I found some papers that use fuzzy logic to solve robotics algorithmic problems. But I have recently been told by a few roboticists that fuzzy logic should not be used in robotics because it has ...
1 vote
1 answer
69 views

Strange phase case in Bode diagram of a transfer function [closed]

Please help me to solve my problem: This is the transfer function: $G(s)=10\frac{(s^2+1)(s-10)}{s(s+0.1)(s^2+2s+100)}$ I calculated properly the whole Bode diagram apart from the phase of the complex ...
1 vote
2 answers
79 views

How many stages necessary to stabilize position while controlling torque?

I'm assuming that since torque translates into acceleration, the basic transfer function from torque to position becomes $1/s ^ 3$ Does this mean that 3 pid controllers are required to properly ...
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1 vote
0 answers
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Theory behind wheeled inverted pendulum robots [closed]

I'm trying to get a deeper understanding of the theory behind wheeled self-balancing robots. Can anyone point me to a text on dynamic modelling and control theory that might help?
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1 vote
1 answer
305 views

What is exact model of haptic interface system in the paper "Time-Domain Passivity Control of Haptic Interfaces"?

I am trying to simulate the experiments in the paper "Time-Domain Passivity Control of Haptic Interfaces", Hanaford and Ryu, 2002, IEEE transactions on robotics and automation vol .18, No1 about the ...
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0 votes
2 answers
546 views

Why ODE for optimal control theory?

I am trying to understand optimal control theory which forms the base for reinforcement learning techniques in AI. Whenever I open a lecture or a book or any online notes, everything starts with an ...
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2 answers
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What is difference between RoboEarth and KnowRob? [closed]

I am not able to clearly differentiate between the two platforms: RoboEarth, and; KnowRob.
1 vote
2 answers
4k views

Difference between Degrees of Freedom (DOF) and Degrees of Motion (DOM)

What is a difference between degrees of freedom (DOF) and degrees of motion (DOM)? I know that DOF is the number of independent movements a manipulation arm can make and robot system can have max 6 ...
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2 answers
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Does a controlling system need to be more complex than the system being controlled?

Is there any theoretical principle, or postulate, that states that the controlling system has to be more complex than the system being controlled, in any formal sense of the notion "complex"?
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Papers on Algorithms in Robotics [closed]

I'm a CS student and I need to give a 30-minute lecture about 1-2 papers describing 1-2 algorithms for any of the main problems in Robotics (navigation, coverage, patrolling, etc.). I have no ...
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2 votes
1 answer
175 views

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

From Introduction to Robotics by J.J. Craig, chapter 2, Page no. 36: Could anyone explain how that equation was derived/formed? I am stuck on this page due to failing to understand where the equation ...
-2 votes
1 answer
73 views

Which math course will be most beneficial? [closed]

Let me know if this should be on Academia instead, but I posted it here to get responses specifically from people active in robotics development. I'm currently an undergraduate student completing ...
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5 votes
1 answer
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role of chi2 in SLAM back-end optimization

All-most all SLAM back-end implementation compute chi2 estimates. Chi2 computation is usually used to compute the best-fitness score of model to the data. How it is related to optimization framework ...
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1 answer
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I want to be a guy of robotics [closed]

I will be beginner need a help-I want to gain knowledge about robotics so it need a basic theoretical knowledge what is the best way to start?
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2 answers
67 views

Perfect implementation of Asimov's 3 Laws

After seeing the movie, I, Robot, I got this question. If Asimov's 3 Laws (actually implementing law 1 automatically implements the other 2) are perfectly implemented on a quantum computer that ...
1 vote
1 answer
116 views

Shortest path using wave planner?

How could I compute the shortest path between point a and b using wave planner? I don't see how using the wave planner would give me the shortest; it would just give me a path! As far as I can tell, ...
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3 votes
2 answers
93 views

Why models are not perfect to represent robotic environments?

Sebastian Thrun says in his paper on Particle Filters that - no model however detailed fails to represent the complexity of even the simplest of robotic environment. What does he means by this? Can ...
4 votes
3 answers
2k views

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

A screw is defined by a six dimensional vector of forces and torques. It can represent any spatial movement of a rigid body (as written here). But I don't get the following distinction between screw ...
6 votes
2 answers
1k views

Taylor Series expansion for EKF

In Probablistic Robotics by S. Thrun, in the first section on the Extended Kalman Filter, it talks about linearizing the process and observation models using first order Taylor expansion. Equation ...
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2 votes
2 answers
225 views

How do I select the best configuration for a known workspace, load and task?

Given workspace constraints, load and task to be done, how do I select the best configuration of my robot? How do I select between a cartesian or Scara robot for instance? How do I select a ...
12 votes
2 answers
4k views

Differences between Ackermann steering and standard bi/tricycles concerning kinematics?

I got the following homework question: What are the general differences between robots with Ackermann steering and standard bicycles or tricycles concerning the kinematics? But, I don't see what ...
14 votes
2 answers
868 views

Does RRT* guarantee asymptotic optimality for a minimum clearance cost metric?

The optimal sampling-based motion planning algorithm $\text{RRT}^*$ (described in this paper) has been shown to yield collision-free paths which converge to the optimal path as planning time increases....
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7 answers
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What algorithm should I implement to program a room cleaning robot?

For this question assume that the following things are unknown: The size and shape of the room The location of the robot The presence of any obstacles Also assume that the following things are ...