Questions tagged [manipulator]
manipulator is a device used to manipulate materials without direct contact.
121
questions
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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 ...
4
votes
1answer
34 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 ...
1
vote
1answer
70 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 ...
0
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0answers
37 views
How to combine URDF files in pybullet?
I have a URDF file for the Kinova Gen3 robotic arm (6 dof) and a URDF file for a suction end effector that was built for a UR5 arm. I am able to load the file for the arm along with a table and some ...
1
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1answer
35 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 ...
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1answer
44 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 ...
1
vote
4answers
130 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 ...
0
votes
0answers
43 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?...
1
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1answer
53 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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0answers
25 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 ...
1
vote
1answer
27 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 ...
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0answers
15 views
.How to draw obstacles in c-space for my 2DOF scara robot?
I want to use A* algorithm for my robot path planning in c-space. But now I want to map the obstacles from cartesian-space to configuration space. I am building a visualizer in python to see all the ...
0
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1answer
32 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 ...
1
vote
2answers
86 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 ...
0
votes
1answer
84 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 ...
1
vote
1answer
44 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 ...
1
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1answer
57 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://...
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0answers
30 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 ...
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1answer
236 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 ...
0
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1answer
28 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,
...
0
votes
1answer
110 views
How to calculate displacement of the end effector by the yaw, pitch, and roll in the spherical joint?
For planar robots, we can calculate how small changes in the angle of each joint corresponds to the displacement of the end effector, by constructing a jacobian consisting of cross products between ...
4
votes
2answers
189 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 ...
2
votes
1answer
43 views
How do I decide the minimum number of link lengths and joints my manipulator must have from the configuration space?
I have a configuration space in 3D where my manipulator must reach certain points. Taking into account all the factors how do I decide the mininum number of links and joints my arm must have?
0
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1answer
59 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 ...
1
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1answer
69 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 ...
0
votes
1answer
179 views
Inverse Kinematics with Orientations
Let's say I have a robot consisting of a base $B$ and a manipulator $M$. The pose of the manipulator can be expressed as the transformation matrix $T_{BM}$. I also have a goal $G$ which I want to move ...
2
votes
2answers
126 views
Controlling the pose of a manipulator using inverse kinematics
I want to control a robotic manipulator in Cartesian space, using inverse kinematics. I know that I can do this using $\omega=J^{-1}v$, where $\omega$ is a vector of joint velocities, $J$ is the ...
2
votes
2answers
262 views
SLERP velocity and acceleration (3d Orientation interpolation)
Hey guys I am quite new to quaternions and I am a bit unsure as to how to use them. How are the velocities and accelerations trajectories determined using quaternions?
I have been using slerp to ...
5
votes
1answer
159 views
Cartesian Impedance control Damping Design (Double Diagonalization)
In the literature, it is often seen that for a system:
\begin{align}
\Lambda \ddot{e} + D_d \dot{e} + K_d e = F_{ext}
\end{align}
A dynamic damping matrix is required for a robot to take ...
0
votes
1answer
56 views
How do I find the minimum time for computing a trajecotry for a robotic arm?
I am studying robotics and I am focusing on trajectory planning.
I have been struggling with this topic for a while, and I still have some doubts that I cannot solve. One of them is the following:
I ...
2
votes
1answer
125 views
How do I assign the origin of the frames in the Denavit Hartenberg convention?
I am studying the Denavit Hartenberg and to practice I am using the following manipulator:
I have been able to assign some of the frames almost correctly, but i did some mistakes I cannot understand. ...
2
votes
2answers
188 views
What is the reasoning for solving inverse kinematics problems?
I am a student, and I am studying robotic arm manipulators. I am focusing on the concept of inverse kinematics, I have understood is the process of finding, from the direct kinematics, the joint ...
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0answers
134 views
Jacobian Derivative (Analytical?)
If I understand this correctly, given the Jacobian Derivative $\dot{J}(q)$ derived using the method presented from the paper by (Rhee, J. Y., & Lee, B., 2017)
where the algorithm summarized ...
2
votes
1answer
36 views
Why applied joint torque will affect another joint?
I want to ask a very simple question.
For the robot dynamics Newton-Euler algorithm, suppose there is a two-link planar robot, we can write the simple dynamic equation form as $M(\theta)\ddot{\theta} ...
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0answers
27 views
What is canonical grasp?
What is a canonical grasp and how is it different from normal/other grasp? I've searched through internet and forums but haven't found any answers.
0
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1answer
72 views
Newton-Euler Inverse Dynamics by Screw
I paste this algorithm from textbook Modern Robotics P294 in chapter 8:
This is coordinate invariance of Newton-Euler equations. In the textbook, they use the ...
4
votes
1answer
185 views
Understanding Impedance Control
I have a question regarding impedance control for a robotic manipulator.
Given that we have a task space trajectory:
$\ddot{x}$, $\dot{x}$ and $x$
And the dynamics model of the robot:
$$\tau = M(q)\...
1
vote
2answers
35 views
Can workspace of a manipulator change after considering its dynamics?
As per my knowledge, the workspace of a manipulator can be determined if one knows the forward and inverse kinematics. But is it possible that the workspace of the manipulator can change after ...
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0answers
58 views
Find the kinematic parameters using DH by Craig convention
I am trying to find the kinametic parameters using the J. Craig of the DH parameters for the following 2-DOF robotic manipulator.
where $\ x,y $ are the axes of the reference frame and $\ q_1 , q_2 $...
0
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2answers
51 views
What does "resolution of a sensor" mean? [closed]
I am studying robotics and I am focusing my attention on the sensors used on robot manipulators. I have seen that there a proprioceptive sensors, such as encoders, and exteroceptive sensors, such as ...
2
votes
2answers
191 views
Why in trajectory planning in joint space the manipulator never crosses a singularity?
I am studying robotics kinematics and I have studied that if we plan a trajectory in joint space it is impossible for the robot manipulator to cross a singularity during its motion, while in cartesian ...
1
vote
1answer
110 views
How to define the degrees of freedom of a flexible manipulator?
Consider a cable-driven flexible manipulator which has 3 cables. Consider the 3 cables to be actuated by 3 motors. Assume that by pulling the three cables in different configurations, we can span the ...
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vote
2answers
80 views
Problem defining rotation matrix
I am studying robotic kinematics , and given the following manipulator with its D-H frames assigned:
I have to find the rotation matrix $R_{e}^{2}$, which is the rotation matrix of frame $e$ with ...
0
votes
1answer
181 views
What is a simple way to assign frames to a robot manipulator using D-H convenction?
I am studying the forward kinematics for robot manipulators, and I am focusing on the Denavit Hartenberg convenction for assigning frames to the various joints of the manipulator.
The problem is that ...
0
votes
1answer
21 views
How to use artificial potential function in manipulator path planning?
The artificial potential method always takes robot as a point, if the manipulator is 6 degrees of freedom, how to use this method in path planning while six links can avoid the collision.
0
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1answer
32 views
What is the difference between multi-link flexible manipulators and continuum robots?
I read the review[1] on flexible manipulators, the modeling method of multi-link(even if single-link) flexible manipulators seems very different from the continuum robots like OctArm(multi-section), ...
0
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1answer
87 views
Visual-Positioning Method
I'm working on mobile manipulator and trying to do visual-positioning of the end-effector.
My camera will located around 1-2 meters from the robot.
I'm sure i cant use color tracking method because ...
0
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2answers
112 views
Model of two link rigid manipulator
I am working on parameter estimation of a rigid two-link manipulator as shown in the picture below.
Unlike the cylindrical links shown in the above image, my robot has links of oval shape.
So the ...
0
votes
1answer
28 views
Kinematics and dynamics analysis of manipulator in zero gravity
Is there any change in the analysis of kinematic and dynamic analysis of the manipulator which is working in zero gravity or microgravity?
3
votes
1answer
415 views
Converting from Modified to Standard Denavit Hartenberg
This is probably a noob question.
But as of right now I am having difficulty converting from the Modified DH to a Standard DH parameters for the Franka Emika Panda. I need standard because it allows ...