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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76 views

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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60 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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263 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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92 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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59 views

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
143 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
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?
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1answer
108 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
64 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
139 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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70 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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583 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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54 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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311 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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72 views

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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176 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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38 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
60 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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796 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
687 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
160 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
193 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
47 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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120 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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1answer
55 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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1answer
416 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
38 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
28 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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1answer
86 views

What is wrong with the assignment of X axis in 5DOF robot manipulator's kinematic diagram?

I tried to solve below question by Edx course. One part of the requirement was to assign frames and find the DH parameters of the given robot manipulator. I assigned the x and z axis as below and find ...
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1answer
100 views

Verifying DH parameters. Unexpected Output

There is a rotating base joint #1 with z/joint axis pointing up and atop sits and arm with 3 z/joint axis facing away from the viewer. The elbow joint F2 has a kink before it of 90 degrees measuring ...
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37 views

Link collision avoidance for redundant manipulator

I am trying to have my robot arm follow a trajectory while avoiding collisions between obstacles and the robot links. The way I go about it is to find the closest point on the robot arm, and treat the ...
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46 views

I want to Calculate the Joint Velocities and Angular Accelerations of 5 DOF Youbot kuka robotic arm

I'm working on an assignment where I need to derive Velocity Kinematics for 5 DOF Youbot kuka robotic arm manipulator. I want to Calculate the Joint Velocities and Angular Accelerations of 5 DOF ...
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1answer
62 views

How to design a controller for a robotic arm given two velocity profiles

See image for reference: Essentially I have a robotic arm with two linear actuators. Lets say, for example, I wanted the endpoint on the arm (where you see the stepper motors) to move purely in the x ...
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63 views

PD controller tuning for flexible joint robotic arm

I am trying to tune the gains of my PD controller for a single axis flexible joint robot. The controller output is the motor torque. My question is: how can i tune the PD gains if the output (torque) ...
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2answers
108 views

What should be the ideal ratio for link lengths ( L1/ L2) of a 2 link manipuator robot with revolute joints?

I am working on making a CAD model of a two link robotic manipulator, with link lengths around 15-20 cm. I am unable to figure how to set their mutual ratio and I want to know whether there is some ...
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1answer
163 views

Jacobian of a planar manipulator with 4 links

I have a mobile manipulator that moves on the plane. The base moves in SE(2) and the manipulator is also planar with 4 links. The mobile base will be a differential drive robot and its motion is ...
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29 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.
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1answer
194 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)\...
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15 views

Increase frequency of status messages from UR5

I know the UR5 is sending me messages with its status (I can't yet understand them though, but I'm already working on that). However, they are too far apart to be useful: It sends them every 0.1 s. ...
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1answer
54 views

Interpret 560 byte msg from UR5 firmware 1.8 through TCP socket

I am trying to use the UR5 from my computer without having to write any script on the robot. For that, I opened a TCP socket as a client from my computer (in a C program), and the robot indeed does ...
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3answers
73 views

Does increasing robotic arm's speed cost replayability?

i've been researching robotic arms for a personal project. I'm a computer engineering student, made some projects with arduino but my knowledge about robotics is currently limited. So i was wondering,...
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0answers
43 views

How To Run the kuka_experimental program on github In RViz?

I have installed Ubuntu 14.04 and installed ROS Indigo in order to run the kuka_experimental source code which can be found on github. I have built the catkin workspace and compiled the ...
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20 views

Increasing suction force

I'm trying to increase the suction force of the end effector in a pick and place system. Is it a good idea to add an extra vacuum pump and put it in parallel? AFAIK, having an extra pump in parallel ...
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1answer
697 views

Does a vacuum pump have to run constantly in a pick & place system?

I'm reading this article about which of vacuum pump or venturi vacuum generator is more efficient for a pick and place system: https://fluidpowerjournal.com/pump-or-venturi/ The example application ...
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1answer
53 views

Robotic vision eye-in-hand research

I started researching Robotic Vision topics for a while but I found myself a bit stuck. My background is in the Computer Vision and Machine Learning fields but I lack the knowledge in robotics. My ...
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1answer
90 views

Modeling of Robots

There are mainly two approaches for controlling robots (mobile robots and static robots): 1) working with kinematic equations, controlling joint or wheel speeds , 2) working with dynamic equations and ...
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1answer
162 views

Torque calculation for a shaft end effector

I would like to calculate the max torque and the rpm to select the right motor. the application does not require a very fast rotation speed (rpm) however it should be accurately controlled. I ...
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2answers
124 views

Speeding Up UR5e Joint Movement

I am working with a Universal Robots UR5e. I am attempting to do a simple back and forth movement of 60 Degrees with Wrist 2, operating at 2 Hz (back and forth in 0.5s). Looking at the Joint Limits, ...
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1answer
153 views

How do I add a tool to an inverse kinematic solver

This may be a very basic question, however I am having great difficulty to find the right answer. I have a functioning python code for the inverse kinematics of a 6 axis UR Robot. For any ...
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2answers
161 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 ...

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