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Questions tagged [manipulator]

manipulator is a device used to manipulate materials without direct contact.

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28 views

Number of inverse kinematics closed form solutions for ABB IRB 140

I've read that 6 dof manipulators give eight closed form solutions, according to a paper. What is the number of iK solutions for the ABB IRB 140? (last three axes intersect but there is a offset ...
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0answers
21 views

Task Space Control Parameters for 6-Dof Manipulator

I'm developing a Task Space controller based on speed for a Universal Robot 5. I've already calculated the Jacobian, position and rotation error for the classic control method: The method works fine ...
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1answer
31 views

What is the difference between the pose of a robot and the configuration of a robot?

Do "configuration" and "pose" means the same thing? If not what is the difference?
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1answer
40 views

Why do I need impedance control?

I am having a hard time understanding the impedance controller. I see that it looks at the manipulator as impedance and the environment as admittance. However, it is hard to grasp the concept and ...
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1answer
24 views

Why does degree of freedom only consider continuous values?

In the book Modern Robotics Chapter 2 Configuration space, we are told that degrees of freedom only considers coordinates with real valued continuous range. Why is this the case?
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13 views

Control Algorithms for Kinesthetic Teaching

There are several algorithms for post-processing of kinesthetically demonstrated motions for manipulators learning a task. However, I have failed to find papers/research work on modeling the ...
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2answers
187 views

Inverse Kinematics - How to only find a unique joint angle solution in 4 dof robot?

I have to develop an algorithm to determine the necessary joint angles to achieve a desired TCP position and orientation in a 4 joint manipulator. I have come across a concept called "degeneracies", ...
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1answer
70 views

D-H parameters verification

This robot has 2 revolute joints in advance then one cylindrical joint, then one revolute joint, then another cylindrical joint, then three revolute joints at the end. There is no D-H table for that ...
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1answer
127 views

Which motors are specifically used for UR3 (Universal robot arm) [closed]

I am looking for the specification of UR3, peak torque and rpm.
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2answers
241 views

Understanding MoveIt! and OMPL more deeply

I wanted to know the actual mathematics behind the path planners MoveIt! uses for manipulators from OMPL. I tried to look into source codes but couldn't get enough details. I wish to know: How cost ...
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0answers
69 views

Orientation problem between Gripper and Object ??

I am working on a pick and place project using ROS & MoveIt!, I wrote my own pick and place functions which generate grasp poses according to the pose of the object and then automatically picks. (...
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1answer
83 views

zero-g mode for UR10 gravity compensation

I would like to freely move my UR10 arm in response to an external force, just like the zero-g mode for Baxter robot, which can be activated by holding its wrist. The Baxter documentation on zero-g ...
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0answers
175 views

Developing world-frame Jacobian using product of exponentials [closed]

I am going through different texts (Spong Robot Modeling and Control, Murray Mathematical Introduction to Robotic Manipulations) and I am seeing different Jacobians developed for the same RRRP ...
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1answer
801 views

D(q) Inertia Matrix and the Jacobian Matrix

There is something I need to verify. Say we have the following RPR robot manipulator. The DH table yields 3 rotational matrices: \begin{equation} R^0_1, R^0_2, R^0_3 \end{equation} Using these ...
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1answer
80 views

Urdf as a way to model dynamics?

Since urdf format serves the purpose of kinematic model but also extends for dynamical properties such as mass,moment of inertia and centre of masses, can it be considered a viable dynamical model of ...
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1answer
232 views

Significance of link length ratio in serial manipulator

I am formulating a problem to optimize link lengths of 3R serial manipulator shown below : I do not assume any explicit relationship between the link lengths, but in one of the papers (http://www....
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1answer
198 views

Dynamics of a robot manipulator with a force acting on the end-effector

I have this exercise The dynamic model is $B(q)\ddot{q}+S(q,\dot{q})\dot{q}=\tau+\tau_k$ Where $B(q)$ is the inertia matrix, $S(q,\dot{q})\dot{q}$ are the centrifugal and Coriolis terms, $\tau$ is ...
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2answers
464 views

Why does the Denavit-Hartenberg representation fail to capture the length of the last link in my model?

The length of the last link (1.73) of my model (of a human finger) is not represented in any of the parameters that I calculated using the Denavit-Hartenberg algorithm, which I think can't be right. I ...
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2answers
417 views

How to check reachability of manipulator to a point?

I have written a MATLAB code for inverse kinematics of 3R robotic arm, which returns value of joint angles for given link lengths and end effector position and orientation. But if location of point is ...
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1answer
244 views

Optimization of link lengths for 3R serial manipulator

I am trying to formulate an optimization problem for determining link lengths of 3R manipulator shown in picture below, Following are the constraints, Robot arm should be reachable at point x = 100, ...
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1answer
52 views

How can serial manipulator have unique condition number for given end effector position?

I am reading about Condition Number which is considered as measure of manipulability of robotic arm, it is defined as $$ k = \parallel J \parallel \parallel J^{-1} \parallel $$ Where, $$ \parallel J \...
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2answers
255 views

Validation of dh parameters

I am working on a concept of robotic arm for which I have fixed DH frames and parameters. Is there any way to validate the correctness of DH parameters and frames ?
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2answers
626 views

how to make a configuration space of a robot manipulator?

How to make a configuration space of a robot manipulator from a work space ? it's robot manipulator is 3 degree of freedom. Is a robot manipulator with more degrees of freedom the same process ?. Do ...
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1answer
417 views

Euler-Lagrange Dynamic model

I'm working on a masters thesis and need to calculate Mass inertia matrix ($M$), Coriolis/Centrifugal matrix ($C$), and the gravity matrix ($G$) in the equation $M\ddot{\theta} + C\theta + G = \tau$ (...
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1answer
671 views

forward and inverse kinematics of arm

I'm trying to figure out to a problem with a planar manipulator. The manipulator has a base effector and L1 and L2 with 3 joints. Question: INVERSE KINEMATICS Given the ...
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2answers
948 views

Calculating the singular configuration of a 3 revolute joint manipulator

I would really appreciate it if somebody could help me calculate the singular configuration of this simple manipulator I am confused since J is a 2x3 matrix and I cannot simply calculate the ...
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1answer
153 views

Is it possible to control joint torque using the position input and torque feedback?

So I am working with a UR10 manipulator which doesn't have a direct torque interface. However, it provides torque/velocity/position feedback for each joint as well as position/velocity interfaces for ...
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1answer
366 views

DH parameters of a PUMA-type manipulator

I'm struggling to find the DH parameters for this PUMA-type manipulator that yield the same results as the author (1): The way I'm checking if the parameters I have are correct is by comparing the ...
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1answer
481 views

Symbolic Representaion of Links and Joints: How to sketch complex manipulators using simple symbols?

In some papers and books we can see that authors using symbols to represent robot arms. My question is, is there a convention for such sketches? If so could you provide a reference which shows how ...
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2answers
549 views

Different methods to determine DOF: Chebychev-Kutzbach-Grubler method vs. Screw method

I'm familiar with Chebychev-Kutzbach-Grubler method to determine degree of freedom of a robot arm. But it seems this method fails to calculate the mobility of some parallel robots, as explained here. ...
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1answer
73 views

Robot Graphical Representation in Real Time

I'm working with a robot intended to be placed in a tele-echography environment. To control the robot I'm using a 6D space mouse that control each degree of freedom of the robot. However, since the ...
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2answers
80 views

Are scissors what I want for moving straight up and out?

I'm a programmer. I had a tiny amount of experience building robots in college a few years ago, but haven't done anything since. I'd like to build a robot that can move around my house, pick items up ...
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1answer
604 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
168 views

How to use RL (Robotics Library) with Xcode?

I came across RL to program robotic manipulators. But according to the website, currently supported websites are Ubuntu and Windows only. Since Ubuntu and Mac OS are based on UNIX kernel, is it ...
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0answers
69 views

Cloth (non-rigid body) manipulation with computer vision? [closed]

I am currently working on a prototype device to automate cloth ironing task. So basically the mechanical design involves 4 manipulators and a separate manipulator arm with a hot pad (iron) to ...
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3answers
2k views

How to decide links length of manipulator?

I'm working on pick and place robotic arm with 4 dof. I'm using MATLAB for inverse kinematics. But, I want to know how to decide links length. Say, I have four point in space upto where my robotic arm ...
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1answer
105 views

Integrating Forward Kinematics Map

Let the forward kinematics map be denoted by $\mathcal{F}$ such that $\mathcal{F}: \theta \in \mathbb{R}^{n} \rightarrow g \in SE3$ Let the minimal representation of $g$ be given by $x \in \mathbb{R}...
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1answer
564 views

showing error while using inverse kinematics “ikine” for 4 dof robotic arm

I want to do forward dynamics but before that I got struck in inverse kinematics for 4 dof. My code is given below: ...
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1answer
95 views

Pick and place using only vision information and forward kinematics [closed]

Is it possible to do pick and place tasks using only forward kinematics and object detection information from a camera? I want to avoid having to do inverse kinematic calculations for my robot. Is ...
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2answers
158 views

Dealing with fixed transformations while solving inverse kinematics

I am trying to solve inverse kinematics (using the Jacobian pseudoinverse method) for a 7 DoF arm, but because of the way the robot is mounted, the base frame does not coincide with the frame of the ...
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2answers
332 views

Inverse kinematics: how to specify TCP constraints in an iterative algorithm?

I am trying to write some simple code to perform IK for a 6 DoF redundant robot using the Jacobian pseudo-inverse method. I can solve IK for a desired pose using the iterative method, and I want to ...
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3answers
1k views

how to manipulate arm robot? [closed]

I want to make a robot arm with a gripper that can go to any x y z coordinates near it. the robot itself will be simple just servo motors and Arduino but I don't know how to make reach the desired ...
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4answers
2k 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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1answer
347 views

Rostock Delta Robot 3D Printer Degrees of Freedom (DOF)

What is the degrees of freedom (DOF) of the Rostock delta robot 3d printer (delta mechanism that consists of three prismatic joints)? Here's the link to the delta mechanism I'm referring to: https://...
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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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2answers
2k views

Difference between Degrees of Freedom (DOF) and Degrees of Motion (DOM)

What is a difference between degrees of freedom (DOF) and degrees of motion (DOM)? I know that DOF is the number of independent movements a manipulation arm can make and robot system can have max 6 ...
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1answer
250 views

Anthropomorphic Arm

I developed an anthropomorphic arm (structure in aluminium) with 6 DOF (3 plus spherical wrist) for direct kinematic. I chose magnetic rotary encoders to measure angles but I am not satisfied, due ...
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1answer
554 views

Robotic manipulator Jacobian by product of exponentials

I've taken a class and started a thesis on robotics and my reference for calculating the Jacobian by product of exponentials seems incorrect, see: http://www.cds.caltech.edu/~murray/books/MLS/pdf/...
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2answers
254 views

Optimal trajectory for manipulators using optimal control

I'm trying to implement direct-multiple shooting method to my problem. ...
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2answers
1k views

Calculate required motor torque through Harmonic Drive

I have a term project which is controlling a two-link manipulator with harmonic drive installed at each joint. To control, i used Computed control method to determine the torque needed for each joints ...