# Questions tagged [manipulator]

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

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### 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 ...
1 vote
1k 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. ...
339 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 ...
72 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
84 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 ...
1 vote
72 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://...
1 vote
43 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 ...
1 vote
663 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 ...
46 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, ...
279 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 ...
470 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 ...
81 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?
706 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 ...
341 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 ...
348 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 ...
1 vote
95 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 ...
270 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 ...
1k 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 ...
1 vote
487 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 ...
3k 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 ...
1 vote
42 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 ...
1 vote
50 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.
445 views

56 views

### Fuzzy logic controller for controlling a four-bar linkage

I am trying to design a control system to move a joint of four bar linkage according to desired trajectory. A dc-motor is used to move the joint. Can fuzzy logic controller be used to solve this ...
1 vote
342 views

### Effiecient computation of coriollis matrix

I want to perform kinodynamic motion planning on a 6DoF hybrid manipulator. I calculated mass matrix, coriollis matrix etc using the lagrangian method. The coriollis matirx was calculated symbolically ...
408 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 ...
1 vote
56 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 ...
4k 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?
112 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?
1 vote
25 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 ...
1k 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 ...
2k 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 ...
1 vote