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.
181
questions
0
votes
0
answers
39
views
kinetic and potential energy of 3 DOF robot having 2 cylindrical links
Assume two uniform cylindrical links robot has 3 DOF as shown in the figure. Where link one has 1 dof that is rotation on its main axis. The second link has 2 DOF yaw and pitch movements. I can ...
- 1
0
votes
2
answers
62
views
Is the angular velocity vector the derivative of a time-varying quantity?
On page 111 (section 4.6) of Robot Modeling and Control (Second Edition) by Spong, Hutchinson and Viyasagar, the authors define a "body velocity" vector $\xi$ of the end-effector as follows:
...
1
vote
0
answers
57
views
PD control with gravity compensation
Given the robot dynamics of the form
$$M(\theta)\ddot{\theta}+C(\theta, \dot{\theta})\dot{\theta}+G(\theta)=u$$
where the notations have the standard meaning ($M$ is the inertia matrix, $C$ is ...
0
votes
1
answer
30
views
How to compute the force applied to point P given the torque registered by the sensor?
I have the following set up:
I want to understand how to compute the force that is being applied to the F_knife point given the Force/Torque registered by the sensor at T_Sensor. The position vector ...
- 11
0
votes
1
answer
33
views
Define system forward dynamics with sympy
I would like to model the dynamics of a robot via the usual discretized system of equations
$$
x_{k+1} = f(x_k, u_k) \qquad x\in\mathbb{R}^{n_x}, \quad f:\mathbb{R}^{n_x}\times\mathbb{R}^{n_u} \to \...
- 211
3
votes
1
answer
174
views
Calculation of IMU offset for Placement of Inertial measurement unit away from centre of mass
I am working on a 6DOF IMU that contains a 3-axis accelerometer and a 3-axis gyroscope. I am building a project to plot the position and orientation of a vehicle/dirt bike in a 3d plane. However, the ...
- 43
1
vote
1
answer
235
views
Center of gravity offset for accelerometer and gyroscope readings
I am working on a 6DOF IMU that contains a 3 Axis Accelerometer and a 3 Axis Gyroscope.
I am building a project to plot the position and orientation of the turret/cabin in a crane in 3D space.
The IMU ...
- 43
1
vote
1
answer
47
views
Determine the maximum joint velocities for a PTP-Movement
Assuming an industrial robot performs a PTP movement with a speed of 100% for each joint, it often happens that the joints never reach 100% of speed because the torque limits of the actuators are ...
- 13
1
vote
2
answers
114
views
Estimating angular velocity from position
If you have two position estimates $P_{t_1}$ and $P_{t_2}$ and times $t_1$ and $t_2$ how do you extract the average angular velocity from them? The linear velocity is a simple difference but how do ...
- 273
3
votes
1
answer
62
views
Articulated Body Algorithm with gear ratio
I am reading up on the proposed articulated body algorithm by Featherstone, which goes like:
Pass 1:
\begin{equation}
\nu_0 = 0\\
\nu_i = {^i}X_{\lambda(i)}\nu_{\lambda(i)}+s_i\dot{q}_i\\
c_i = \nu_i \...
- 53
0
votes
0
answers
21
views
Compute acceleration / spatial acceleration corresponding to additional control torque / external force for some open robotic chain
Given a robot ( open chain ) for which we know q,q_dot, q_ddot, and Tau_{measurement}. (one can consider that these parameters are found using some sensors attached to the robot) I would like to be ...
- 1
2
votes
1
answer
40
views
In Dynamic Motion Primitives, why we need to approximate f if f_target is given?
I seem to misunderstand something crucial regarding finding the force vector in the process of DMPs:
The way I understand it, I should come up with a dataset of trajectories $\{y_i\}_{i=1}^n$, and ...
- 121
2
votes
1
answer
119
views
Finding error in euler angle from quaternion
I'm currently working on creating a ROS controller package for franka arm, which I choose to implement a feedback linearization controller that works as following:
Assume we have a planned trajectory $...
- 21
0
votes
0
answers
22
views
Why Potential Energy in Spong's book is positive?
All books I've came across (i.e. Craig, Siciliano, Frank, Niku, and Carlos) state the potential energy of a $i$th link is negative except in Spong's book
Is there a particular reason for the ...
- 2,453
1
vote
1
answer
38
views
what does free or forced torque mean in robot arm dynamics?
I'm trying to understand the dynamics (torque , velocity, etc ) of how a simple 2 DoF robotic arm rotates.
I am using the RoboAnalyzer simulator 1 .
It has a Inverse Dynamics setting of "Free&...
- 11
0
votes
0
answers
42
views
Combining dynamic movement primitives to create new ones
this is my very first question and I want to thank everyone for the massive contribution to the community!
On to my question now, here is a quick definition of my idea/problem:
I have created a "...
- 1
0
votes
1
answer
52
views
Body angle of a centre-articulated robot
Wondering if anyone can help me out with this one, or point me in the right direction. I am working on a centre-articulated robot, which is steered via a push-pull chain drive. The chain drive is ...
0
votes
2
answers
66
views
Force sensors output when inclined
So here is the context:
I am working on a motorcycle simulator. It consists of a motorcycle frame mounted on different actuators (see picture on the left).
In particular, the two actuators at the ...
- 21
0
votes
1
answer
77
views
Why in forward bending knee orientation in quadruped legged robot require less torque in knee joint?
I'm trying to find answer in terms of physics explanation, why knee joint torque requirement is less in the forward bending leg orientation of a quadruped legged robot.
I'm referring this article, in ...
0
votes
1
answer
72
views
3-links Robot Dynamic PD Computed Torque Control
I am designing the PD control of 3-links robot using Simulink.
I can't figure out what to do in the 'Robot' block to get the acceleration d_qq back to calculate the error.
What is happening in this '...
- 1
1
vote
1
answer
163
views
How to solve this basic dynamics/inverse kinematics problem
Suppose I have a 6-DOF robot arm with revolute joints whose tooltip is at some position $\bf{r_0}$ and I want to move it through some trajectory ${\bf r}(t)$.
For simplicity, assume there are just 2 ...
- 336
1
vote
0
answers
350
views
Computation of centrifugal and Coriolis matrix
So I have a seesaw-cart electromechanical system which I want to control. It has 2-DOF (the angle of the seesaw $\varphi$ and the cart position $s$).
I used the Euler-Lagrange method to get my ...
- 53
1
vote
1
answer
78
views
Extract the potential energy from the gravity vector
I have a recursive Newton Euler algorithm from which I can compute the gravity vector.
My question is, which is the better way to compute the potential energy?
I know the following relation between ...
- 11
1
vote
1
answer
30
views
Defining the specifications required by a 6DOF robot to impose a harmonic sinusoidal motion
Perhaps a bit of a simple question, but since I don't have a background in robotics/engineering, then I imagine this would be the perfect place to ask such a question.
I am buying a 6-DOF Stewart ...
- 111
2
votes
1
answer
95
views
Equations of motion with mass attached to end effector and external force
I have to find the equations of motion for the given manipulator:
The links of the manipulator are considered weightless and the equations of motion have to be derived by using the Lagrange equations....
- 155
0
votes
1
answer
76
views
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 ...
- 13
1
vote
1
answer
301
views
Peter Corke Robotics Matlab Toolbox the problem of inverse dynamics in the Franka Emika Panda model
I have the following question about the Franka Emika Panda dynamic model. In case I perform the solution of the inverse dynamics problem using Robotics Toolbox (Peter Corke) I get different results ...
- 11
0
votes
1
answer
137
views
Kinematic Bicycle Model theta units
I don't understand the $\theta$ units. The bicycle model defines $\theta$ as:
$$\theta=\theta +\frac{v\cdot\tan\delta}{L}\cdot$$
Where $v$ is the vehicle velocity, $L$ is the wheelbase distance, and $\...
- 111
2
votes
1
answer
138
views
Holonomic constraints on an upright wheel
A wheel moving in free space has the six degrees of freedom of a rigid body. If we constrain it to be upright on a plane and to roll without slipping, how many holonomic and nonholonomic constraints ...
0
votes
1
answer
90
views
Implementing Dynamic Balancing on Robot Dog
I made a robot dog using Lewansoul LX-16a Smart Serial bus motors and a 3D printed body. I am using an Arduino Mega 2560 to control everything. I already have the inverse kinematics working. But for ...
0
votes
1
answer
125
views
what is difference between twist and classcial velocity
In ch 8.2.1 Classical Formulation in the book Modern Robotics by Frank C. Park
I know some remarks about this formula.The origin of coordinate system is coincidence with the mass center of the rigid ...
- 17
1
vote
1
answer
167
views
perplexity about ch8.2.1 the linear dynamics, in the book <modern robotics>
From previous chapters, I think I have understand the twist, it is about the angular velocity and the linear velocity, the difference is that linear velocity is not one fixed point in the body but is ...
- 17
0
votes
0
answers
43
views
Spherical Parallel Manipulator Lagrangian problem
I faced a very serious problem and I urgently need the help of specialists in robotics, mechanics, physics and mathematics.
I am trying to derive equations of motion from the Lagrangian of a spherical ...
- 183
1
vote
0
answers
34
views
Multidimensional obstacle avoidance in ODE. Part II
Multidimensional obstacle avoidance
https://math.stackexchange.com/questions/4146255/multidimensional-obstacle-avoidance-in-ode
For some time, I studied this question more closely and came to the ...
- 183
1
vote
1
answer
169
views
Jacobian of Euler's rotation equations
I propagate the attitude of a satellite in a free-floating, torque free environment from $t_k$ to $t_{k+1}$ by integrating Euler's equation of motion:
$$ \dot{\omega} = [J]^{-1}([\omega]_{\times}[J]\:\...
- 21
0
votes
1
answer
56
views
Multidimensional obstacle avoidance
Artificial potential barriers are known that allow robots to avoid obstacles. They are constructed as follows. https://authors.library.caltech.edu/106548/1/2010.09819.pdf
Can you please tell me how ...
- 183
0
votes
0
answers
23
views
Looking for a course (online?) RE: systems with XY stages
Using XY stages is common in many fields:
3D printing
Genetics instruments
semiconductor lithography
automated microscope slide imaging
See for example https://www.asml.com/en/technology/lithography-...
- 103
0
votes
1
answer
89
views
How to calculate center of mass with a prismatic joint
Suppose we a 1DoF planar robot with only 1 prismatic joint (for the sake of the example).
The prismatic joint can extend the link or shrink the link.
Suppose the length of link 1 is a, and suppose ...
- 1
2
votes
1
answer
133
views
Range of a heading angle [0,2π) or [−π,π)
Consider the unicycle dynamics in 2D plane:
$$\begin{array}{l}
\dot x = v\cos \varphi \\
\dot y = v\sin \varphi \\
\dot \varphi = \omega
\end{array}$$
What is the range of the heading angle $\phi$? ...
- 189
1
vote
0
answers
37
views
Ground based path generation from RGBD camera
How does one generate a trajectory for a ground vehicle using an RGBD camera? For a drone it's simpler since you're not constrained by having to move on the ground but it's not clear to me how ...
- 273
2
votes
1
answer
120
views
Velocity-Control of a manipulator without a dynamic model
I have a five DoF robot. Each axis is connected to a cylinder. You can send PWM values to each cylinder and you are able to read out the position values of each cylinder which makes it possible to ...
- 314
0
votes
2
answers
345
views
Quadrotor dynamics: How is torque created
I'm a software engineer and I've recently engaged into Robotics field. I've started by a course on Coursera which talks about Aerial robotics and thus quad-rotors. I'm trying to understand how quad-...
- 147
0
votes
1
answer
43
views
When is the Quadcopter out of the control?
Assuming ideal environment/hardware flying conditions, is it possible that the autopilot loses the control of the quadcopter?
What is the maximum tilt in roll and pitch that is allowed for the ...
- 101
4
votes
2
answers
288
views
Stationary/inertial reference frame
In Modern Robotics by Kevin Lynch, there is a term "stationary" frame, but this is never defined. Googling shows that this is synonymous with inertial frame.
Apparently inertial frame means ...
- 161
0
votes
1
answer
744
views
how to find Singularity and jacobian Inverseof 5 DOF Robotic arm?
I am working on calculating the Jacobian Determinant to find the singularity of my 5 DOF Robotic arm, I have calculated the jacobian matrix, and the matrix I got is a very large value
As it is non ...
0
votes
1
answer
89
views
What is the difference between The state-space equation and The configuration-space equation
The craig(p.180) states that equations can be made to represent the dynamic equations. The first one being the state space equation.
$\tau=M(\Theta)\cdot\ddot{\Theta} + V(\Theta,\dot{\Theta}) + G(\...
- 17
2
votes
2
answers
277
views
How to calculate potential enegy of manipulator dynamics?
I'm trying to obtain dynamics of a 4 DOF robot. Firstly, I calculated all Transformation matrices and Jacobians. While solving Lagrangian there is two main things one is kinetic energy and the other ...
0
votes
1
answer
203
views
How to calculate potential enegy of manipulator?
I'm trying to obtain dynamics of a 4 DOF robot. Firstly, I calculated all Transformation matrices and Jacobians. While solving Lagrangian there is two main things one is kinetic energy and the other ...
3
votes
1
answer
402
views
Motion profile and Motion control scheme, how do they interact?
I'm studying motion control and I start with the simplest case, I have to go from A to B in a straight line using a trapezoidal motion profile.
I understand that in a real case, due to the fact that ...
- 33
3
votes
1
answer
571
views
How to calculate Inertia tensor?
I'm trying to obtain dynamics of a 4 DOF robot. Firstly, I calculated all Transformation matrices and Jacobians. While solving Lagrangian there is a term I - Inertia tensor . I couldn't understand the ...