Questions tagged [dynamics]

Dynamics is a branch of applied mathematics (specifically classical mechanics) concerned with the study of forces and torques and their effect on motion, as opposed to kinematics, which studies the motion of objects without reference to its causes.

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267 views

Computing Yaw angle from position and velocities

I have an object to whom I know the x,y,z position, length, width, height, and x,y velocities. Is there a possibility to compute the yaw angle from this information?
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2answers
568 views

Combining centres of mass and Inertia tensors

I'm trying to build the dynamic model of a 6DOF robot, and the company that has built it, kindly provides a document having the masses, centres of mass, principal axes of inertia and principal moments ...
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3answers
377 views

Second-order dynamical systems

I have been reading this paper (https://arxiv.org/pdf/1509.06113.pdf), which is about control of a robotic arm. They learn a mapping from robot state to robot control, where the state is the positions ...
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0answers
904 views

Computation of Coriolis Matrix [closed]

I am controlling a 6-DOF robot. For this, I want to compute the Coriolis Matrix. From my study of examples, I understand there are several ways of going about it. At the moment, I am using the theory ...
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1answer
656 views

holonomic and non holonomic constraints in layman's term

I'm new to robotics and I've been reading some slides online regarding motion planning. Due to my lack of knowledge in mechanical engineering, I'm having a difficult time understanding what holonomic ...
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2answers
209 views

Biped State Space Implementation

Currently I working on a humanoid robot using inverted pendulum model and use LQR for walking stabilizer. Input u is Torque, State x is angle and angular velocity and y output is angle. I got the ...
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2answers
903 views

Inverse dynamics for robotic arm using Matlab Simmechanics

I am learning Simmechanics Matlab to do inverse dynamics for 4 DOF robotic arm. I read many examples to input motion to revolute joints like through PID, slider gain, sine waves, signal Builder etc. ...
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2answers
457 views

Mathematical modelling of system dynamic on matlab

I want to make a matlab (simulink) control model for the system in the image below. The original pdf is only accessible if logged in Carleton's Learning Management System. How do I get the dynamics ...
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1answer
1k views

Dynamics of a 3R planar robot manipulator,matrices M(q),C(q,q') and G(q)

The dynamics equation is T=M(q)*q''+C(q,q')*q'+G(q). Can somebody provide me with the M(q), C(q,q') and G(q) matrices of a 3R manipulator with link mass,length and rotational inertia m_i, l_i and ...
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1answer
146 views

Why do I need an additional moment of inertia term in the cart-pole dynamics equation?

I'm trying to understand the dynamic equations for the cart pole system according to this control tutorial from the University of Michigan, where the angular acceleration equation can be written as $(...
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3answers
553 views

Constrained Second Angle Double Pendulum

If I am trying to model the dynamics of a double-pendulum (on a horizontal plane without the effects of gravity), in which the second angle is constrained to range between values of [-10 deg, 10 deg], ...
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1answer
931 views

Parallel axis theorem to determine the moment of inertia

I need to use the parallel axis theorem to determine the moment of inertia of each robotic arm link referred to the joints of the 3 DOF manipulator. The moments of each link's centre of mass are: The ...
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2answers
991 views

What is the bicycle model for a dynamic robot?

I was asked this in a phone interview for a robotics job. Googling has not really helped. I assume it is some sort of state prediction model that can be used in a Kalman filter. Can anyone give me a ...
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4answers
3k views

Dynamic torque simulation for a 6 DOF robotic arm

I am working on a 6 DOF robotic arm(industrial manipulator). I have the basic structural specs (dimensions, weights etc) for the links and joints with me. Basically, I want to simulate both static ...
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3answers
19k views

Position Control vs Velocity Control vs Torque Control

Please can somebody explain to me the difference between Position Control, Velocity Control, and Torque Control? Specifically, I am thinking in terms of a robot arm. I understand that position control ...
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2answers
2k views

Damping vs Friction

I am using a physics simulator to simulate a robot arm. For a revolute joint in the arm, there are two parameters which need to be specified: damping, and friction. If a torque is applied to the joint,...
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1answer
2k views

Why do series elastic actuators have more accurate and stable force control?

The other day, somebody was telling me about a robot in their lab, and they mentioned that it has "series elastic" actuators. But after doing a bit of Googling, I'm still not sure as to what this ...
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3answers
698 views

How to apply A bang-bang signal of amplitude 1 N and 1 s width as an input force to reproduce certain results in Matlab?

I working on dynamic modeling and simulation of a mechanical system (overhead crane), after I obtained the equation of motion, in the form: $$ M(q)\ddot{q}+C(q,\dot{q})\dot{q}+G(q)=Q $$ All the ...
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2answers
108 views

motor inertia tensor?

In modeling dynamics of a robot ,in which servo motor is adjusted inside the link, there is a need to find inertia tensor of the motor itself,Right? So if it is needed how can i get the inertia ...
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1answer
90 views

Dynamic Model of a Manipulator

I'm stuck on equation 4.30 of page 176 in http://www.cds.caltech.edu/~murray/books/MLS/pdf/mls94-complete.pdf This equation: $\frac {\partial M_{ij}} {\partial \theta_k} = \sum_{l=\max(i,j)}^n \Bigl( ...
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3answers
28k views

What's the difference between a holonomic and a nonholonomic system?

I was wondering if a 1D point mass (a mass which can only move on a line, accelerated by an external time-varying force, see Wikipedia - Double integrator) is a holonomic or a nonholonomic system? Why?...
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1answer
83 views

Euler-Lagrange systems, autonomous or nonautonomous?

I was reading an article on Euler-Lagrange systems. It is stated there that since M(q) and C(q,q') depend on q, it is not autonomous. As a result, we cannot use LaSalle's theorem. I have uploaded that ...
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1answer
542 views

Dynamic model of a robot lifted by a balloon (Multibody system)

I'm having a hard time trying to understand how to obtain the dynamic model for a system similar to the image. The balloon is a simple helium balloon, however the box is actually an aerial ...
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1answer
208 views

Wind flow diagram of a quadcopter

I'm trying to determine the wind flow diagram around a quadcopter when it is in action. I looked up on internet but couldn't find any reliable source. By wind flow diagram, what I mean is when my ...
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1answer
294 views

List of books similar to Thrun's Probabilistic Robotics for robot mechanics and manipulation [closed]

What? Put together here a list of books (like the one for C/C++ on StackOverflow) that are spiritually similar to Sebastian Thrun's Probabilistic Robotics for robotic manipulation and mechanics. Why?...
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4answers
2k views

Optimal location of the center of mass for an inverted pendulum

I'm building an inverted pendulum to be controlled by DC motors, but I've run across a conundrum. Personal life experience tells me that it's better to have a lower center of mass to maintain balance....
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1answer
1k views

Mass Matrix in Lagrange equation

I want to find the equations of motion of an RRRR robot.I have studied about it a bit but I am having some confusion. Here, in one of the lectures I found online, it describes an Inertia matrix of a ...
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2answers
284 views

Do walking robots use accelerometers?

My understanding of walking robots (e.g. https://www.youtube.com/watch?v=xJlkBBdyBYI) is that they use a gyroscope to determine the current orientation of the robot, or each joint of the robot. This ...
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1answer
251 views

Calculating required torques for a given trajectory using Lagrange-Euler

I have a 2DOF robot with 2 revolute joints, as shown in the diagram below. I'm trying to calculate (using MATLAB) the torque required to move it but my answers don't match up with what I'm expecting. ...
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3answers
314 views

Dynamic simulation of compliant elements in quadruped robot

I have a preliminary design for a legged robot that uses compliant elements in the legs and in parallel with the motors for energy recovery during impact as well as a pair of flywheels on the front ...
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1answer
612 views

Relationship between earth frame attitude and acceleration for a quadcopter

For a quadcopter, what is the relationship between roll, pitch, and yaw in the earth frame and acceleration in the x, y, and z dimensions in the earth frame? To be more concrete, suppose roll ($\theta$...
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0answers
80 views

Torque control in eye-in-hand visual servoing

In most papers about IBVS the camera velocity is computed and then used as a pseudo-input for the manipulator. (e.g. this one) Is there any work in which the dynamic Lagrange model $H(q) \ddot q +C(q,\...
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2answers
94 views

Should the therotical parameters match the physical setup constraints when modeling a robot?

I'm working on modeling and simulation of robotic arm, after I obtained the mathematical model of the robot, I used that to implement some control techniques, to control the motion of the robot. The ...
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3answers
85 views

Mathematical Moddeling of Elastic Robots [closed]

We can easily compute the rigid robot kinematics and dynamics. There is many resources, simulators and modelling tools about it. But i couldnt find any of these for elastic robots. Can you suggest ...
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2answers
786 views

Where to make changes for simulation project Bullet/Gazebo/ROS/Orocos

I am starting to develop robotics project which involves simulation (and maybe real world programs) of soft-body dynamics (for food processing) and clothes/garment handling (for textile industry or ...
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1answer
220 views

Matlab: System simulation with dynamic state matrix / input matrix [closed]

I have the following system: $$\dot{x} = A(t)x+B(t)u$$ $$y = x$$ $A(t)$ and $B(t)$ are actually scalar, but time-dependent. If they would be constant, I could simulate the system in Matlab using: <...
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2answers
460 views

Adding an Actuator or Force to a (Featherstone) Articulated Rigid Body Model

I'm working on a project where I need to model a system that is essentially comprised of a series of ball-and-socket joints attached to a base, which is attached in turn to a prismatic joint (rail). ...
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2answers
4k views

How to implement PID control for robotic arm?

I'm wondering that, PID control is a linear control technique and the robot manipulator is a nonlinear system, so how it is possible to apply PID control, in this case. I found a paper named: PID ...
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4answers
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how to implement tracking problem with PID controller

I'm trying to implement the tracking problem for this example using PID controller. The dynamic equation is $$ I \ddot{\theta} + d \dot{\theta} + mgL \sin(\theta) = u $$ where $\theta$ : joint ...
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4answers
238 views

Why I'm getting very long terms in the inertia matrix (or dynamics model) of the robot using matlab script?

I'm working on the dynamics model of a RRRR articulated robot, I'm following Euler-Lagrange approach and developing my code in m-file in matlab; I'm looking for dynamic model of this form: $$ D(q) \...
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1answer
488 views

Converting a linear acceleration command into a DC motor command?

I'm constructing a 2 wheels balancing robot which uses a PID controller. I've tuned my parameters on numerical simulations based on a continuous inverted pendulum system so that the simulated ...
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1answer
108 views

What dynamic system could these equations represent?

I have equations of a dynamic system. I need to figure out what this physical system is. The equations are: \begin{align} \dot{x}_1&=bx_1+kx_2+x_3\\ \dot{x}_2&=x_1\\ \dot{x}_3&=\alpha (...
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2answers
321 views

“Time-varying” and “nonautonomous” dynamical systems and their Lyapunov analysis

It is possible to distinguish the properties "time-varying" and "nonautonomous" in dynamical systems regarding Lyapunov stability analysis? Does it make a difference if the system depends explicitly ...
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2answers
3k views

How do quadcopters turn left and right?

In this picture, a sketch of a quadcopter is displayed with rotor's direction of motion. The magnitude of the rotational velocity is depicted by the thickness of the lines (thicker lines are higher ...
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1answer
150 views

The IDE using for programming the Atlas robots

ATLAS Gets an Upgrade - the new video of the Atlas robot is out so I'm curious about the IDE with which they are coding this thing.
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3answers
585 views

Proportional controller error doesn't approach zero

I'm reading this pdf. The dynamic equation of one arm is provided which is $$ l \ddot{\theta} + d \dot{\theta} + mgL sin(\theta) = \tau $$ where $\theta$ : joint variable. $\tau$ : joint torque ...
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1answer
271 views

Dynamic tracking precision of UR5/10

I am willing to use a universal robot arm (UR10) in a path following mode. i.e. I have a desired trajectory for the robot's effector and I would like the effector to follow it as close as possible. ...
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3answers
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 ...
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1answer
158 views

Can inverse dynamics control be regarded as a function?

I know that inverse kinematics ($p \rightarrow q$, p: desired pose of the end-effector, q: joint angles) is not a function because there might be multiple joint angle vectors q that result in the same ...
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3answers
992 views

Compensating for Yaw in Lateral Quadcopter Movement

I'm trying to make a quadcopter move laterally at a certain angle. I've been able to find the proper roll and pitch angles for this (that work with a yaw of 0°); how would I adjust these values to ...