Questions tagged [kinematics]
Kinematics is the branch of mechanics dealing with the motion of points and objects.
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Orientation Problem of a 4-DOF manipulator
As shown in figure, I have a 4-DOF manipulator.
I want to control the robot such that the end-effector should always be pointing down no matter where the robot is in the end space. For the ...
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40 views
Finding torque equation for my robotic arm
I am designing a 5 dof robotic arm, and for that I would like to find a torque equation. However, I am a little confused here:
According to me the torque equation for M1 should be l2m2+l3m3+l4m4+l5m5 (...
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1answer
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How can I input joint angles to transformation matrix to get position in matlab?
I am trying to get the forward kinematics for a robot model in matlab (rigid body tree).
I created a 4 x4 transformation matrix from the base to the end-effector using the gettransform() function. I ...
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16 views
Robotic Tasks in relation with components
I will try to ask the best i can:
Our Human Body has parts like arms, legs, head etc. An arm can rotate 360 degrees. Arm has a hand with five fingers which can grip, poke, push etc.
How would we ...
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27 views
how to find the kinematic and dynamic model of the mechanism
enter image description here
5 links 4 revolute joints find the kinematic and dynamic model ,link 3 should be horizontal with ground and one end of link 1 and 5 there are sliders enter image ...
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52 views
Calculating wheel linear velocity from body velocity
A frame {b} is attached to the centre of a robot chassis. The planar configuration is given by $(x,y,\phi)$ where $\phi$ is the angle between the x axis in {b} and the x axis of a fixed reference ...
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1answer
55 views
Omnidirectional Movement for 3 Wheeled Spherical Omni wheel robot
I was watching James Bruton's video on his spherical omniwheeled robot and he was explaining how to go directly sideways. He explains this from 6:09 to 7:06. I didn't understand how the velocity of ...
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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-...
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inverse kinematics robot RRR
I realized an analisis of inverse Kinematics but I couldnt solver the equations that I find.
the robot is RRR
I believe that this problem have solution however I didnt find in the web :( if somebody ...
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27 views
velocity and acceleration of end effector
assume we have maximum angular velocity and maximum angular velocity for each joint in 6 DOF manipulator.
now how can we calculate maximum velocity and acceleration of end effector at any path planing?...
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6DOF kinematic robotic arm programm
I am trying to find a well documented library which I can use for my 6dof robotic arm (https://www.thingiverse.com/thing:1693444)
But I cant find anything :(
Does anyone have a python/c code for ...
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91 views
6DOF Kinematics moveo
I asked on stackoverflow for the DH-Parameter for my robotic arm (moveo bcn3d).
I also copied the arduino code of Skyentific (YouTuber). Modified it to match my settings but i still does not work. Can ...
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50 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 $\phi$? ...
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1answer
42 views
Calculate Torques & Forces From Jacobian Matrix
Dear Robotics Stack Exchange,
I am trying to calculate the torques and forces for a 2DOF robot.
I’m used the partial differentiation method to find the Jacobian matrix. I managed to find the ...
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1answer
26 views
How to find Joint Angles or Theta for 7DoF Robotic Arm
I am trying to find the joint angles or at least theta to be used to find the Denavit-Hartenberg Parameter for a robotic arm (Baxter's right arm). I have the link lengths and such, but I don't know ...
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Deduce all possible configuration for a given CONF param FANUC
I am working on the "CONF" parameter of FANUC Robots.
The "CONF" param determine the pose of the robot (maybe to have only one inverse kinematics solution). This configuration is ...
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1answer
31 views
Parallel spatial mechanism - DOF
The parallel mechanism is composed of a moving platform
and a base (or frame) connected by four legs. Each leg is composed of five
revolute joints numbered 1, 2, … 5 from the base to the moving ...
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1answer
35 views
Elegant way to mathematically relate joint positions (without a root/base joint) for easy re-rooting?
I'm pretty new to robotics, but have learned about the tranformation matrices and how to relate relationships between joints using transformation matrices.
I just wonder if there is a system that ...
2
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1answer
70 views
How to find angular velocity using pure pursuit algorithm?
I have implemented the pure pursuit algorithm for my differential wheeled robot as described in the following paper:
http://www.enseignement.polytechnique.fr/profs/informatique/Eric.Goubault/MRIS/...
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0answers
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Forward kinematics confusing point
I am studying robot arm kinematics. In order to construct a transformation from a global coordinate frame to the end effector frame, I have seen references to the Denavit–Hartenberg (DH) convention. ...
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1answer
40 views
Can a 6 DOF robot have multiple inverse kinematics solution with a constrained rotation/orientation
I trying to understand how manipulators robot works (6 DOF)
I would like to know if the inverse kinematics (IK) solution give only one or multiple solution if we include the rotation (3x3 matrix) of ...
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0answers
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Difference between Denavit-Hartenberg and Rodrigues formulas/conventions
I am trying to compute the forward kinematics for a 6 DOF robot arm.
I've found two methods : the Denavit-Hartenberg (original and modified) and the product of exponentials with the Rodrigues formula.
...
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1answer
54 views
What type of electric motor and speed-controlled circuit do I use to bounce a hanging, 5 pound weight? (it's for a Halloween decoration)
I'm trying to make a roughly 5 pound, hanging halloween decoration bounce on a string from about 1-3 times per second, preferably at variable speeds if I can.
I've looked up a simple DC motor circuit ...
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0answers
9 views
How to Calculate Individual Axis Commands Out of 5 Axes G-Code?
I am dealing with 5 axis CNC machining time prediction. I would like to ask the question with providing some background and mentioning the constraints which what I concluded from some of the ...
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26 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 ...
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1answer
56 views
Inertial frame's angular velocity expression
I'm following a robotics course on coursera which talks about aerial robotics and more specifically quadrotors.
I'm trying to understand the logic behind the relationship between the angular velocity ...
2
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1answer
74 views
Inertial frame VS Body-fixed frame momentum correction factor
I've recently enrolled in a Coursera aerial robotics course and i'm trying to understand how the rate of change of the angular momentum is computed from the inertia frame to the body-fixed frame.
...
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57 views
Path curvature in kinematic bicycle model
I'm trying to develop an understanding of the control law for longitudinal and lateral control for self driving cars. While doing so, I came across the kinematic bicycle model which is used to derive ...
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0answers
14 views
What is the mathematical relation between phi1, phi2, phi3 and motor PWM values for 3 wheel omni drive robot?
My question is that I cannot deduce the relation between phi1, phi2, phi3 values of the omni robot (3 wheeled) and the motor's PWM values, since I'm planning on designing the robot to perform "go ...
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0answers
107 views
Simple inverse Kinematic algorithm
I was looking for a simple inverse Kinematic algorithm that doesn't depend on eigen(doesn't work on my machine + dependency conflict never fixed it)
Most of the code out in the internet is way to ...
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1answer
93 views
5 bar linkage hand exoskeleton
I have a project to design a hand exoskeleton for hand rehabilitation. The problem is that i'm thinked I only need the linkage mechanism with multiple 4 bar linkages. But because of human fingers ...
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2answers
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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 ...
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1answer
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How do I calculate components of an angular rate on end effector frame?
I’ve helped develop the forward kinematic chain for a two-axis gimbal. The Denavit-Hartenberg parameter table for the kinematic chain is given below.
$\theta$
$\alpha$
$r$
$d$
$90^{\circ}$
$90^{\...
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1answer
162 views
Denavit-hartenberg parameters sign 6-DOF
Trying to understand how does the Denavit-Hartenberg work.
While I understood how is the table constructed, I however don't understand how are the signs for the orientation parameters (theta, joint ...
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1answer
145 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 ...
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2answers
56 views
Adding 90 degrees to DH parameter
I am trying to learn DH parameters for this anthropomorphic arm is.
What I understand is robot's/or serial arms can have different initial position.
But here, how is theta 3 = theta 3 + pi/2?
I am ...
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2answers
50 views
Why do we say a robotic arm have 2 dof even though the two joints rotates along the same axis?
Why do we say a robotic arm has 2 degrees of freedom even though the two joints rotate along the same axis? Why isn't it called a 1 dof robot?
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How can we estimate reliable angular motion from a monocular camera?
While I am working on a project, a question comes to my mind; how can we estimate reliable angular motion from a monocular camera, just for a typical indoor environment within a few seconds? So to ...
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1answer
26 views
How can I find the kinematics 2 differential drives attached together along their axes?
I have a system like shown in the diagram
where 2 robots having differential drive are physically constrained together. Traditionally for a single robot, we find the Instantaneous center of curvature (...
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2answers
85 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 ...
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1answer
48 views
Cartesian control for $z$ vector of end effector frame to point towards a specific direction
Consider a robotic manipulator with 7-DOF (all joints are revolute) that accepts joint velocities as execution commands. What I am trying to achieve is the following:
I want to calculate the ...
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1answer
60 views
Problem designing acceleration inputs controller
I am reading this paper: https://www.researchgate.net/publication/224635390_The_motion_control_problem_for_the_CyberCarpet
in which is implemented a cartesian regulator to bring the position $(x,y)$ ...
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1answer
72 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
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1answer
72 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 ...
0
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1answer
89 views
Forward Kinematics for Two Axis Gimbal Mount
I'm trying to work out the orientation of a block at the end of two axis gimbal. I know the position of the two rotational joints, but would like to calculate the final orientation of the block given ...
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1answer
38 views
C space for R5 manipulator
Trying to create a collision avoidance model (RRT) for an RRRRR manipulator. I am unable to wrap my head around how to represent the same in configuration space. Anything upto 3 joint variables is ...
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1answer
37 views
How can I find a robot's distance from an object given FOV, bounding box measure, and image width and height in pixels?
The robot is standing in the middle of the arena. I am confused on how to convert the pixels into a real life distance and how to use the bounding box. Starting help is appreciated.
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1answer
182 views
Multi-Link Robot Degrees of Freedom
I want to compute the DOF of this system if it composed of (n) such links grasping this common object using Grubler's formula obtaining the solution as a function of (n), considering this to be a ...
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1answer
117 views
Compute orientation velocities 6-DOF robot
I am trying to compute the joint velocities a 6-DOF manipulator(a typical industrial robot).
I have an initial position [xi, yi, zi, T1i, T2i, T3i] and goal position [xf, yf, zf, T1f, T2f, T3f] in the ...
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1answer
133 views
Chebychev–Grübler–Kutzbach Formula of Degree of Freedom
I always have had a problem understanding Chebychev–Grübler–Kutzbach Formula of Degree of Freedom:
$$d = 6\,n - \sum_{i= 1}^{m}\left( 6 - f_i\right)$$
where $n$ is the number of moving links, $m$ is ...
