Questions tagged [robotic-arm]

The arm tag is intended to be used for questions relating to robotic arms from, small hobby arms with only 1 or 2 degrees of freedom to large industrial robots with complex joint assemblies. For the ARM CPU, use the tag arm-cpu.

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7 views

How to calculate Inertia tensor?

I'm trying to obtain dynamics of a 4 DOF robot. Firstly, I calculated all Transformation matrices and Jacobians. While solving Lagrangian there is a term I - Inertia tensor . I couldn't understand the ...
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Proximity sensors in ABB injection molding robot system

I would like to know the purpose of the 4 proximity sensors, how are they related to the sequence of the robot and the injection molding machine ABB injection molding
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Fastest cobot arm?

I'm working on a pick and place use case that needs to be extremely fast, while working in contact with human workers without safety barriers. What is the fastest cobot arm available on the market ...
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1answer
19 views

I'm looking for a simplified control scheme for a game-rendered robotic arm

I'm a programmer, but not savvy with robotics (to lay a baseline for my lack of knowledge). I have a game-simulated arm that allows me to set joint angles which it will automatically move the joints ...
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2answers
63 views

No electric motors can handle being stalled for even short periods of time, even at low power. Is this statement true in all cases?

We were using a regular POLOLU d.c motor whose stall current is 0.36A. We want to use this motor in a robotic hand where the motor will be stalled while holding the object. We are limiting the current ...
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33 views

What type of rigid body rotation can best be learned by neural networks?

I am training a reinforcement learning network in simulation for a robot which at the current stage learns Euler Angles to rotate the end-effector based on the actual state. The performance is overall ...
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1answer
26 views

Does 6DOF robot arm + linear rail = 7DOF arm?

Assume we have a 6DOF manipulator, take UR5 as an example. Does adding a linear rail, on which the robot sits, add a 7th DOF to the system, making it equivalent to a 7DOF manipulator? Any caveats?
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How I Calculate the correct Joint Torques of Robotic arm in Simmechanics?

I have imported my Solidwork Robotic arm into Simmechanics successfully, now I want to calculate torque required for each joints at different conditions, I cant find the Torque, I have tried Total ...
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1answer
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Determining Base Configuration Tsb from End-Effector Configuration Tse for youbot

Hello there, hope you are doing great. Right now I am trying to control youbot to pick and cube and place it to a certain position, on simulation. However, I believe that the reference trajectory is ...
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1answer
33 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 ...
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1answer
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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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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
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Simulation of Robotic arm

I want to simulate my 5 DOF robotic arm, in such a way that the calculated Torque and mass values of each joints (Servos) defined to be tested that are they capable of physically bear all the weight ...
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1answer
33 views

Time Mapping for Robot Arm Teleoperation

I have a 6DOF robotic arm that I wish to teleoperate by tracking my own hands. For the sake of simplicity, let us assume a 3DOF arm where only position is fed, and the orientation is constant. ...
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What should be the required operating voltage for Servo motors in my 5 DOF robotic arm, with 50 kg payload

These are the estimated torque values of all axis in our applications 1st Axis- 226.57 oz-in - 478oz-in 2nd Axis- 756 oz-in -1590oz-in 3rd Axis- 356 oz-in - 749.7 oz-in 4th Axis- 188 oz-in - 395 oz-...
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1answer
63 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 ...
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1answer
35 views

What can a Point-to-Point Robot do?

What are point-to-point controlled robots actually good for? Only pick and place tasks? Since continuous path controlled manipulators can do anything a p2p robot can do, plus tasks that require a &...
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Natural frequency of robot arm

I want to design a 3 DOF pick and place robotic arm. I've accomplished stress analysis. now i'm going to do frequency analysis. software give me natural frequencies in different configurations. but i ...
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What is a “vacuous matrix”?

I am currently learning about robotic grasping and came across a matrix $H_i \in \mathbb{R} ^{l_i \times 6}$ which selects $l_i$ components of the relative contact twists and sets them to zero. My ...
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1answer
30 views

digital servo won't seek to angle if delta between current position and target is more than ~15 degrees

My students and I are using a Hiwonder LD-220MG digital servo to position a "shoulder" on a robot. We are seeing a behavior (on every one of these servos that we test) that it won't go ...
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1answer
30 views

Handling Inverse Kinematics error on a UR Robot

We're working on a bigger system that'll use two UR robots as well (although we only have one at the moment for development). We're communicating with the robot through its TCP/IP based RTDE protocol ...
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1answer
29 views

Rapid code pick and place

Considering the scenario represented in the following image, and the function open_gripper(), close_gripper() and Offs(), present the necessary instructions for the robot to perform the path 1 - 2 - 3,...
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output velocity equation of compliance control

I am trying to implement a compliance controller for a robot arm and stumbled upon an existing code snippet where the compliance velocity of the endeffector is calculated by: $v_{out} = v_{in} + \frac{...
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1answer
23 views

How to find inertia parameter of payload automatically

I know of several robot manufacturers who can perform automatic inertial measurement for 6 axis robots. Fanuc, for example, moves with axes 5 and 6 each from +180 to -180 °, once with and once without ...
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1answer
33 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?
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1answer
35 views

Counterweight in arm designs

I wonder why most robotic arms use large J2 (shoulder) motors rather than counterweights. What sort of complexity do they add to the design beside increase in overall weight? In fact, rather than ...
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1answer
46 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 ...
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1answer
39 views

Can ROS be an alternative for a KFLOP or RUMBA Board?

I have a few questions about controlling robot arm motion. I see that some have used Dynomotion KFLOP and other CNC motion controllers to control arms. Some have used Rumba board as well as several ...
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1answer
46 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 ...
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1answer
50 views

Jacobian to determine the linear velocity of each node (DOF 3 RRR robot arm)

I've done the FK and IK for this robot: On those I seem to be able to get to the positions I want on the simulator so I'm assuming nothing is wrong with my FK and IK calculations. I've tried to ...
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43 views

From an end-effector trajectory to joints movements

let's assume that our robot consists of 3 degree-of-freedoms. In order to move the end-effector of this robot along a straight line, these 3 joints have moved as below: Now, if the desired end-...
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34 views

Quaternionic feedback for for cartesian impedance control

I've seen that there are plenty of ways of generating orientation errors with quaternions. But the one I've seen most often is the following: For example, say that for a quaternion $Q = \{\eta, \...
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1answer
62 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 ...
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Rotate the end-effector around its Xf axis

I am working on a 7 DOF robot (7 rotational joints). I used euler angles to let the robot point down. Zf (Z of the last frame "end-effector frame") is the direction of the end-effector. What I want to ...
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How to calculate twist and wrench in local and global frames

I am rather new to screw theory and also lost in robotics books' formulas. we have a simulator of a robot arm within Mujoco physics engine and I'm wondering how I can calculate wrench and twist in the ...
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1answer
71 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 ...
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1answer
29 views

how do I decide what is the order of the polynomial I need to use in a polynomial iterpolation for a trajectory?

I am a student studying robotics, and I am focusing on trajectory planning for a robotic arm. In particular, I am studying polynomial interpolation for defining the trajectories, and I am having some ...
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1answer
48 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 ...
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1answer
65 views

Why with the pseudo-inverse it is possible to invert the Jacobian matrix even in a singular configuration?

Consider the following situation: I have a robotic arm manipulator with all revolute joints, for example consider a 2R planar manipulator. We know that if we compute the direct kinematics of it, anf ...
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1answer
80 views

How do I compute the derivative of the Jacobian with Matlab?

I am studying robotics, and I am trying to write a Matlab code for computing the derivative of the jacobian matrix. The formula for computing the derivative of the Jacobian is the following: so it ...
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1answer
54 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. ...
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2answers
85 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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1answer
37 views

Problem in Jacobian matrix

I have a 5DOF robotic arm were 4 joints rotates around a Z axis and one around an x-axis. I am not that good with the Jacobian, but I think I have this. $$ J[v,\Omega]=[Z_{i-1}×(O_n-O_{i-1}), Z_{i-1} ...
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1answer
104 views

where can I find a good source to study robotics kinematics and trajectory planning relative to robotic arm manipulator?

I am a student, and I have to study for a Robotics exam which consistes mainly in kinematics for a robotic manipulator and trajectory planning also for a robotic manipulator. In the part relative to ...
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15 views

DH Notation for Bend End Effector of RRR Articulated Arm

Hello, I want to ask about the DH notation for this RRR Robot with special end effector (See in the picture). I have a problem when writing the DH notation from join 3 to the end effector. the L shape ...
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1answer
43 views

Reference frame, vector

How do I specify the directions of a unit vector $X_n$ and $Y_n$ of a frame $\{n\}$ at an angle $θ$ relative to a frame $\{a\}$ in the form $$ X_n=cosθX_a + sinθY_a $$ $$ Y_n=-sinθX_a+cosθY_a $$ ? Can ...
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36 views

What are the steps to calculate inverse kinematics of a robot arm with a flat hand?

The goal is to keep the hand as it extends from the wrist flat at all times, to hold a vertical tool. I've got some great resources that have helped me solved FK and am now struggling a bit with the ...
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1answer
73 views

Understanding types of hand eye calibration

I have been reading about hand eye calibration for a couple days. Basically, I have 2 setups I want to execute hand eye calibration. Camera is fixed in a position and arm is moving (eye on base); ...
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1answer
26 views

Self motion with multiple constraints

I am trying to control a 7 DOF robot (a Franka Panda). I use jacobian based control (resolved rate motion control) to generate a joint trajectory from a cartesian trajectory. My contraints for the ...
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1answer
19 views

Understanding KGf.CM in Camera Robotic Head Design

I am attempting to design a robotic camera head - however, I am struggling to calculate the torque (in terms of KGf.CM) I will require to rotate the Y (tilt) axis of the head. The motor I intend to ...

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