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Questions tagged [kinematics]

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

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2answers
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I'm looking for hands-on experience with different types of leg and hip designs for walking robots [closed]

I'm looking to find out, How do human-like legs compare to chicken legs and four-leg systems. In terms of cost, performance, speed, strength and accuracy. I'm interested in things like speed, agility,...
5
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2answers
2k views

Solving Inverse Kinematics with Gradient Descent

I am trying to implement my own inverse kinematics solver for a robot arm. My solution is a standard iterative one, where at each step, I compute the Jacobian and the pseudo-inverse Jacobian, then ...
4
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3answers
805 views

Computing the Jacobian Matrix — chain rule?

I am learning about robot kinematics and the Jacobian matrix, and I'm trying to understand how to compute the Jacobian matrix given a kinematic chain, such as a robot arm. I understand the theory ...
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1answer
410 views

convert toolframe coordinate to world frame coordinates?

I am not sure how i should explain this, I am looking for a way to plot the trajectory an robot arm. An object is seen from the toolFrame frame, but how do I plot the position of each joint, such ...
2
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1answer
124 views

Mobile robot algorithm implementation error

I am working in reproducing a robotics paper, first simulating it in MATLAB in order to implement it to a real robot afterwards. The robot's model is: $$\dot{x}=V(t)cos\theta $$ $$\dot{y}=V(t)sin\...
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1answer
48 views

Principle of virtual force - General help in understanding / explanation

I'm an Electronics student taking a module in Robotics. From the example, I understand line 1 as the Jacobian is found from the time derivative of the kinematics equation and such relates joint ...
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0answers
41 views

How to determine the angles between a UAV and a sphere

I have an UAV modeled in three dimensions with let's say position coordinates $p_{uav} = (x_1,y_1,z_1)$ that is moving in a direction $d = (d_x,d_y,d_z)$ and a moving obstacle modeled as a sphere with ...
3
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1answer
459 views

inverse kinematics for 6 jointed robots

I am a uncertain about how to compute the right homogeneous transformation matrix to compute an inverse kinematic Q-configuration. Looking at robot like this Where at the end of this robot I have ...
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2answers
188 views

Angle to a circle tangent line

I want to simulate the detection of a moving object by a unicycle type robot. The robot is modelled with position (x,y) and direction theta as the three states. The obstacle is represented as a circle ...
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2answers
1k views

Difference between an underactuated system, and a nonholonomic system

What's the difference between an underactuated system, and a nonholonomic system? I have read that "the car is a good example of a nonholonomic vehicle: it has only two controls, but its configuration ...
2
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1answer
434 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 ...
2
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2answers
776 views

Finding rotation quaternion

I am trying to use a quaternions for robotics and there is one thing I don't understand about it. Most likely because I don't understand how to define position with quaternions and how to define ...
3
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1answer
293 views

Are operational space and joint space dependent on each other?

Some questions about this, my friends and I argued with this problem. Are operational space and joint space dependent on each other? I know that $x_e$ (end effector's pos.) and $q$ (joint var.) can ...
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1answer
194 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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3answers
724 views

How many DOFs required to define a 3D pose

I understand that to be able to define point in 3D space, you need three degrees of freedom (DOFs). To additionally define an orientation in 3D space, you need 6 DOFs. This is intuitive to me when ...
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3answers
2k views

How to find kinematics of differential drive caster robot?

I'm working on a little project where I have to do some simulations on a small robot. I my case I'm using a differential-drive robot as one of the wheels of a bigger robot platform (which has two ...
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0answers
74 views

Accurate technique to locate position? [closed]

What is the most accurate way to locate the position and orientaion of the body during some motion (rotation and translation)? I need to track the body very precisely, the required accuracy is 100-...
2
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1answer
4k views

How to perform odometry on an arduino for a differential wheeled robot?

I am using a differential wheel robot for my project. I need to know the current coordinates of the robot with respect to it's initial position taken as the origin. I m doing the computation on an ...
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3answers
2k views

Forward kinematic computing the transformation matrix

I am the moment trying to compute the transformation matrix for robot arm, that is made of 2 joints (serial robot arm), with which I am having some issues. L = 3, L1 = L2 = 2, and q = ($q_1$,$q_2$,$...
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1answer
2k views

DH parameters and Kinematic Decoupling

Is it possible to decouple a 5DOF manipulator? This question I asked earlier and I believe I got the right answers but I never show the drawings of the manipulator and now I'm hesitating during setup ...
0
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1answer
5k views

Getting pitch, yaw and roll from Rotation Matrix in DH Parameter

I've calculated a DH Parameter matrix, and I know the top 3x3 matrix is the Rotation matrix. The DH Parameter matrix I'm using is as below, from https://en.wikipedia.org/wiki/Denavit%E2%80 Above is ...
0
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1answer
100 views

Relative orientation of two robots

Given two robot arms with TCP (Tool Center Point) coordinates in the world frame is: $X_1 = [1, 1, 1, \pi/2, \pi/2, -\pi/2]$ and $X_2 = [2, 1, 1, 0, -\pi/2, 0]$ The base of the robots is at: $...
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2answers
1k views

Kinematic decoupling

Is kinematic decoupling of a 5DOF revolute serial manipulator also valid? The three last joints is a spherical joint. Most literatures only talks about decoupling of 6DOF manipulators. Thanks in ...
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2answers
10k views

Running my 3 DOF Inverse Kinematics Code: Works in MATLAB, not in Python

I asked a question similar to this earlier, but I believe I have a new problem. I've been working on figuring out the inverse kinematics given an x,y,z coordinate. I've adopted the Jacobian method, ...
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2answers
725 views

Robot arm reachability of a pose in Cartesian space

Given a set of robot joint angles (i.e. 7DoF) $\textbf{q} = [q_1, ... , q_n]$ one can calculate the resulting end-effector pose (denoted as $\textbf{x}_\text{EEF}$), using the foward kinematic map. ...
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1answer
719 views

Mobile Robot path reconstruction by using IMU acceleration and Yaw angle

I hope you can help me with my project. I'm using a skid-steering wheeled mobile robot for autonomous navigation and I'd like to find a way to be able to perform path reconstruction in Matlab. By ...
3
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1answer
1k views

How to use the Homogeneous transformation matrix?

I am trying to understand how to use, what it requires compute the homogenous transformation matrix. I know 2 points from 2 different frames, and 2 origins from their corresponding frames. I how ...
5
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1answer
1k views

How to convert between classic and modified DH parameters?

I currently have a description of my 22 joint robot in "classic" DH parameters. However, I would like the "modified" parameters. Is this conversion as simple as shifting the $a$ and $alpha$ columns ...
6
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1answer
1k views

Hand Eye Calibration Solver [closed]

I have a rig for which I have a pretty good estimate of the static transformation between the camera and a joint based off of the CAD. It has some errors though and I was hoping to fix it by doing a ...
6
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2answers
2k views

Why do we generally prefer DH parameters over other kinematic representations of robot arms?

I am specifically interested in DH parameters versus other representations in terms of kinematic calibration. The best (clearest) source of information I could find on kinematic calibration is in the ...
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3answers
81 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 ...
0
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1answer
39 views

How can a memory alloy be used as an alternative to a compressor found in a refrigerator? [closed]

I'm curious about this alloy and how they say it can be used as an alternative to a traditional compressor. Can anyone explain how this would work? My goal is to understand that use case so I can ...
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4answers
67 views

Assuming I have the angle with respect to two beacons, and know the distance between them, can I localize myself?

Let's assume I have the following situation, and need to find (x,y). Is it possible? There does not appear to be more than one solution to the system, but my trigonometry is a bit rusty. I feel ...
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1answer
289 views

Measuring angular displacement using the TI-SensorTag

I've looked around but can't find the answer, to what I hope is a simple question. I'm working with a TI-SensorTag, and I want to be able measure the rotation around the unit's Z-axis. Basically I ...
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6answers
4k views

How do I work out the kinematic solution of a robot arm?

I draw a robotic arm in Solidworks, but I'm not so sure about how to find out the DOF, forward and backward kinematic. Could anyone help me understand how to work out the kinematic solution of this ...
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4answers
218 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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2answers
2k views

How to find the body jacobain, for each link in a robot manipulator?

The links twist could be obtained, and thus The spatial manipulator Jacobian could be done, but when it comes to the body Jacobian, it is becomes difficult. Moreover, the adjoint transformation ...
4
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3answers
2k views

Jacobian-based trajectory following

I would like to control my 7 DOF robot arm to move along a Cartesian trajectory in the world frame. I can do this just fine for translation, but I am struggling on how to implement something similar ...
2
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1answer
1k views

How to get the 4*4 matrix from the twist using product of exponentials, in robot kinematics?

In robot kinematics, we have $e^{(\theta*twist)}$, where $twist$ is 6*1 vector. How do I get the 4 by 4 transformation matrix by using product of exponentials?
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3answers
2k views

DH Matrix to homogeneous transformation matrix for each joint

Given a DH matrix for a set of joints, how would you convert the data into homogeneous transformation matrices for each joint? I've looked online, but can't find a good tutorial.
6
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1answer
3k views

Can a Jacobian be used to determine required joint angles for end effector velocity/position?

I'm in the early stages of working with a simple robot arm, and learning about the Jacobian and inverse kinematics. From my understanding, the Jacobian can be used to determine the linear and angular ...
7
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1answer
4k views

How do you calculate the moment of inertia of a Quadcopter?

I'm building a quadcopter for my final year project. I have a set of equations describing attitude and altitude but they involve $I_{xx}$, $I_{yy}$ and $I_{zz}$. None of the papers I have read ...
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2answers
315 views

following a trajectory with LQR controller

We want our wheeled robot to follow a (rather short) trajectory. We wrote an LQR controller, which works well in simulation. However, our robot offers two problems: 1.) The reported state information ...
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3answers
706 views

is it possible to track movement on a tennis court?

I'd like to track my run in an indoor tennis court. GPS won't be available so I was thinking researching for other solutions: Accelerometer: I concluded it's a no go because while playing tennis the ...
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2answers
35 views

Short distance ball transport

I'm looking for a way to transport balls (diameter 50mm) 220 mm up with over a slope with a length of 120 mm. Currently I'm considering the usage of a belt system but I cannot seem to find a good belt ...
8
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3answers
4k views

Forward Kinematics/D-H parameters for perpendicular joint axes

I am trying to compute forward kinematics of the Kuka youBot using DH convention: http://www.youbot-store.com/youbot-developers/software/simulation/kuka-youbot-kinematics-dynamics-and-3d-model The ...
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2answers
98 views

Velocity derivatives using Quaternions [closed]

How to compute the angular and linear velocities Quaternions? I am new to this area and although I have studied the algebra I am unable to understand how to compute the velocities.
3
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1answer
453 views

How to get pure end-effector translation through Jacobian?

I have a 7 DOF arm that I am controlling with joint velocities computed from the Jacobian in the standard way. For example: $$ {\Large J} = \begin{bmatrix} J_P \\J_O \end{bmatrix} $$ $$ J^{\dagger} = ...
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2answers
1k views

Position Control of an Omni Wheel Drive Robot

I want to create a robot that will navigate on a desired path! That path can be a straight line or a circular path with a given radius. I will use 3 or 4 omni wheel drive platform and for positioning,...
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0answers
57 views

Can active sensor data be fed into an Autodesk Inventor Simulation?

I'd like to drive the position of various components within a virtual assembly based on sensor data being collected in real time from an external device. Does Inventor support such a setup? The goal ...