Questions tagged [kinematics]

Kinematics is the branch of mechanics dealing with the motion of points and objects.

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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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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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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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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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25 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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22 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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29 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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34 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 ...
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51 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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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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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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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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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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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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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
50 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 ...
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57 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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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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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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Simple inverse Kinematic algorithm

I was looking for a simple inverse Kinematic algorithm that does depend on eigen(does not work on my machine + dependency conflict never fixed it) Most of the code out in the internet is way to ...
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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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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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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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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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99 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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37 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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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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25 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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72 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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40 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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56 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
61 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 ...
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1answer
47 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 ...
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1answer
73 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
36 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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33 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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160 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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97 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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99 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 ...
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How to do a relative rotation of a cuboid such that the longest edge is upright?

I am using pybullet. I have a cuboid with half extents [4,2,1] corresponding to x,y,z dimensions. I rotate this cuboid around the z world axis theta and also translate it by [0, 0, .65]. I take a ...
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142 views

Cartesian Velocity Control between Two 3D Poses

I am really struggling to understand how to do Cartesian velocity control when 3D rotations are involved. So, below is a very simple example which I am hoping somebody can help me with. Let's say the ...
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How to find inertia parameter of payload automatically

I know of several robot manufacturers who can perform automatic inertial measurement for 6 axis robots. Fanuc, for example, moves with axes 5 and 6 each from +180 to -180 °, once with and once without ...
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135 views

Cartesian Angular Velocity

Let's say I have a Jacobian which gives the relationship between the velocity of a robot's joints, and the Cartesian velocity of its end-effector, relative to the end-effector's local frame. And let's ...
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52 views

Design optimization method using indices

There are several methods like manipulability and conditioning index for design optimization kinematics performance, but these methods rely on the singular values of the jacobian matrix. I described ...
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61 views

Dexterity calculation with dual quaternions

How can the manipulability of a robot arm be calculated when the kinematics are described with screw theory such as dual quaternions? These methods are sigularity-free, but what could we say about ...
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1answer
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Difference between constant curvature kinematics and rigid link kinematics

What is the difference between constant curvature kinematics and rigid link kinematics and what is their respective definition?

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