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Questions tagged [manipulator]

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

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How to choose drives for a 6Dof manipulator with a shperical wrist

So my question I guess is tied to design or modelling(Not too sure what topic it falls under) a manipulator according to what I read in the book "Introduction to robotics:mechanics and control&...
Njo_nds's user avatar
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Collision Update on a Manipulator Links

I am trying to apply a pick-and-place operation with the Fanuc 6 DOF robot. I am using Moveit2 to give motion planning commands to robot. It sometimes gets into limit error during the execution of ...
Oben Sustam's user avatar
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Designing the kinematics and Dynamics of a spherical joint as 3 revolute Joint

I am working on a project where I am trying to mimic human like motion and for that I am designing a 7 DOF arm with the spherical joint in shoulder as 3R joints and 2R joints for elbow and 2R joint ...
Anshul Nayak's user avatar
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Can't visualize pre-defined pose in RViz

quite new to ROS. I'm trying to program the trajectory for a 3DoF manipulator using MoveIt! I have been able to visualize it in RViz using MoveIt setup assistant and made sure to setup planning groups,...
Gerardo Del Cid's user avatar
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Control Manipulator/Gripper through EGM Communication ABB

I am a university student and new to robotics. I am part of a semester project where the goal is to directly control the gripper of the robot. The gripper is pneumatic and can be controlled with RAPID ...
b.combs97's user avatar
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120 views

Cant control OpenManipulator on Turtlebot3

I'm using the OpenManipulator on the Turtlebot3 together with Ubuntu 22.04 and ROS2 Humble. When I start the bringup for the manipulator it looks like this: ...
chris98's user avatar
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Bot orienting to same direction regardless of Quaternion value in Moveit

I am trying to control a simulated UR5e bot using ROS. For trajectory planning and execution i am using Moveit. The issue is that when I give a Pose to Moveit, the bot reaches the position (XYZ) just ...
Emaad Ahmed's user avatar
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Open Manipulator python API documentation, or Examples

As stated by the title, is there a way I can access to the python API documentation of the Open Manipulator package? Right now all I can find are service definition such as: https://emanual.robotis....
Ezeuz's user avatar
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gazebo is not lunaching moveit package

I have a ros noetic moveit package a robotic arm having demo_gazebo.launch file ...
Mubashir's user avatar
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1 answer
93 views

How to model the Cable composites in Mujoco Physics Simulation engine

How to name the cable composite in mujoco, also how to add equality constraint to the end of the cable with another body ?
Rishab Kumar's user avatar
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2 answers
386 views

Why is admittance control better than impedance control for huma robot collaboration?

I have seen many papers that use admittance control for human robot collaboration but no one tells why admittance is the choice and not impedance. Is it something very trivial that I should know or ...
Shubham Kumbhar's user avatar
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Transformation Pose

Hi I am doing a transform from the object to the base_link the orientation seems to be right but the positioning is wrong.Here is my code. i had to change the translation values as when i move foward ...
emanuel rodrigues's user avatar
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UR robots always have 2 parallel axes. Why not at a singularity?

I thought I understood the Jacobian and singularities pretty well, but then I was asked: UR robots (and others) have 2 joints that are always in parallel. Doesn't this put the robot at a singularity ...
AndyZe's user avatar
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1 answer
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Standard Notation/Name for Velocity Transformations

I've been looking to see if there's any standard notation for a matrix to convert an end-effector velocity vector $\xi_n^0 = \begin{bmatrix} v \\ \omega \end{bmatrix}$ from one frame of reference to ...
LadyGodiva2's user avatar
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DH parameters of a serial manipulator RRRRRR

I am trying to find the forward kinematics of this manipulator in the picture using DH notation. All of the joints are rotational. I managed to get to the third joint. The parameter table is below. ...
Matěj Kopecký's user avatar
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102 views

When assigning frames in Denavit-Hartenberg (DH) parameters, where do I put the frame on end effector?

I have a simple question, for the last link (end effector) I need to estimate the parameters but when I put the reference frames in the center of the end effector, I just don't know. Last link (end ...
Haisam's user avatar
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Where can I find 6 DOF manipulator packages for gazebo?

Hello. Where can I find 6 DOF manipulator with a 4-wheel mobile base packages for gazebo? Thanks. Originally posted by NickRos on ROS Answers with karma: 1 on 2023-02-14 Post score: 0
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How to calculate Exponential coordinates of end_effector from Transformation matrix

I want to know Exponential coordinates of end effector $\text{S}\theta$(6-vector) from end effector transformation matrix. I calculated the transformation matrix of the end effector from the forward ...
HARCO's user avatar
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How to add gripper to robot arm and plan according to the end effector on Moveit

Hello! I am simulating for a university project, the Elfin 5 robot arm which package can be found here along with a gripper which package is found here. Being new to Moveit, I am finding trouble to ...
user avatar
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Grasp matrix implementation

I've majorly followed Dex-net implementation to calculate a grasp matrix (G) to compute other grasp quality metrics (e.g., Ferrari Canny L1 metric or smallest singular value of G). Based on my ...
HOJUN LEE's user avatar
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138 views

Why the robot is not at the zero configuration

As part of my testing, I was using Kuka's arm to test some kinematic controllers. In the picture below, when the arm is spawned in Gazebo, the positions of the joints are zero (i.e. obtained from <...
CroCo's user avatar
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Meaning of p(q) in the expression for minimum clearance from obstacle for redundant robotic manipulators

Can somebody who has studied Industrial manipulators or has worked on Industrial manipulators using Jacobian Inverse and Jacobian Pseudo inverse algorithm for Inverse Kinematics please explain what ...
Robotics_Enthusiast's user avatar
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1 answer
178 views

definition of self motion

From my understanding, self motion refers to a set of joint velocities which doesn't cause any cartesian motion on the end-effector. Here, by motion it is meant both linear and angular components or ...
dcfg's user avatar
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2 votes
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Redundancy and Null space projection

I'm reading "Theory of Robot Control" by Carlos Canudas Wit, Bruno Siciliano, Georges Bastin. In Task space control chapter, exploiting the redundancy by means of null space as shown below ...
CroCo's user avatar
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How to find workspace of parallel manipulator by monte carlo method?

I am working on a 3 DOF parallel manipulator, I was successful in solving the inverse kinematics and forward kinematics of my manipulator. But I am facing a problem in generating a workspace for it. I ...
Shiv's user avatar
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2 answers
74 views

Is this motion possible for this manipulator?

I'm currently solving the exercises of Modern Robotics book. I came across this problem but it is not clear to me how to approach it. I computed the analytic Jacobian which is $$ \begin{bmatrix} \dot{...
CroCo's user avatar
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2 votes
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190 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....
Teo Protoulis's user avatar
2 votes
1 answer
154 views

Degrees of Freedom

What is the Degree of Freedom for a k-link planar serial chain for k = 2, 3, 6? Using Grüber Formula, I get k-link chain has k Degrees of Freedom. But the maximum DoF in a plane can be 3. I am not ...
kdkvcm's user avatar
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172 views

How to obtain the Jacobian matrix for this 2Planar without differentiation

Take a look at the below picture, I would like to derive the Jacobian matrix without differentiation. In this Modern Robotics book, the screw theory is used. I've derived the forward kinematic using ...
CroCo's user avatar
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1 vote
1 answer
201 views

Feed-forward controller with lookup table

does anyone have experience in implementing a feed-forward controller for a hydraulic cylinder? Often, when a hydraulic cylinder is controlled with PWM values, people (https://drive.google.com/file/d/...
Joe's user avatar
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250 views

Pose of the end-effector

I am trying to get the pose of the end-effector. I have attached the picture. I am stuck. I wrote the transformation matrices - I am not sure how to move forward next. How do I find the end-effector ...
Phoenix in the air's user avatar
1 vote
1 answer
95 views

How to calculate holding and operating torque at the base?

Could anyone please help me with the formula to calculate the operating torque and holding torque at the base to rotate the structure on top of it as shown in image with white arrows? Thank you in ...
Wreck's user avatar
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1 vote
1 answer
472 views

How to calculate operating torque and holding torque of a slew drive for a manipulator arm?

Hope you are doing good and enjoying your weekend. I have a question regarding calculation of torque and tilting moment for a slew drive. Slew drive (motorised) will be used at the base of a ...
techno's user avatar
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7 votes
3 answers
2k views

Why do current manipulators tend to use 7 DoF instead of 6 DoF?

In theory, controlling a 6D pose (3D position + 3D orientation) would require 6 joints, and - assuming the robot is carefully designed - the inverse kinematics should be solvable for that case. Adding ...
FirefoxMetzger's user avatar
4 votes
1 answer
191 views

Why are serial manipulators almost always made of single dof joints?

I am currently taking my first robotics class and I found it curious that all serial manipulators have single dof joints. Why not use joints with more dof and reduce the number of components? Will ...
Eyas Ayesh's user avatar
1 vote
1 answer
1k views

Forward/inverse kinematics and transformation matrices

I have found the homogeneous transformation matrix that can be used to determine the relation between the parent and child links of a robot. This matrix is shown below. $T_i = \left[\begin{array}{ c ...
user463102's user avatar
1 vote
1 answer
109 views

Why is a joint space trajectory unable to deal with operational space obstacles?

I have found several sources that state that a Joint space trajectory model is not capable of dealing with obstacles in the manipulator workspace. These sources include: slide 10 of "Manipulator ...
user463102's user avatar
1 vote
1 answer
117 views

homogenous transformation matrix variants

I am working on some manipulator projects and come across a few variants of the homogenous transformation matrix. I've been working on matlab and they give slightly different answers. Assuming both ...
trex98's user avatar
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2 votes
4 answers
2k views

How to draw robot manipulator diagram

I've been seeing a lot of these diagrams online and wondering how can I replicate this myself. Is there any easy-to-use software package that will allow me to draw these diagrams quickly and ...
trex98's user avatar
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1 vote
2 answers
219 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 ...
Lewis Paterson's user avatar
2 votes
0 answers
153 views

How can i consider orientation of 6dof manipulator for inverse kinematic?

i been trying to code IK solver for few days, and i finally move the robot to the desired position. However im having hard time to orient the end-effector as i want it. I read the "Robotics ...
Haegu Lee's user avatar
1 vote
1 answer
93 views

Force-torque sensor reading when a robot is stationary

Let's say I have a robot arm with a force-torque sensor on the wrist, between the final motor and the gripper. If the arm and wrist are stationary, then what would the reading on the sensor be? I know ...
Karnivaurus's user avatar
0 votes
1 answer
79 views

Sinusoidal trajectory of each cartesian coordinate for the end effector

Consider a 7-DOF robotic manipulator. I want the end effector to follow a predefined trajectory and suppose I care only about the position and not about the orientation. So, the rotation part of the ...
Teo Protoulis's user avatar
2 votes
2 answers
398 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 ...
RAKESH KUMAR K's user avatar
0 votes
1 answer
289 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 ...
RAKESH KUMAR K's user avatar
1 vote
1 answer
99 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 ...
user27243's user avatar
1 vote
1 answer
74 views

My Pick and Place Program Not Working

hope you are all well. I am trying to finish a capstone project on Coursera. It asks me to carry a cube object from an initial position to goal. This video shows the movement. Project website: http://...
kucar's user avatar
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1 vote
0 answers
44 views

Robotic Platforms Similar to the PiBot(Locobot)

I am brain storming platforms to use for a project I am working on. I'm looking for an mobile platform with a manipulator attached. I originally was focusing on the PiBot, but after doing some ...
neerbasu's user avatar
1 vote
1 answer
776 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 ...
Ammar Taha's user avatar
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1 answer
55 views

Is it possible to control a 5 DOF manipulator in the 6 DOF Task Space?

I am referring to pre-computed torque control techniques that are based on the Task Space dynamic model. Maybe by using pseudo-inverse for the Jacobian and the task space inertia matrix ? Cheers, ...
Dawi's user avatar
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