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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1answer
98 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 ...
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0answers
10 views

what kind of slewing bearing and gear(spur or helical) use in first axis(wrist) of arm robot?

I want to design an arm robot. for first joint motor is runoff the axis. I decide to use slewing bearing. in catalog there are bearing with spur gear. but I think because of backlash its accuracy is ...
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1answer
39 views

Reducing stress on servo axle

I am designing an articulated robot arm that will not need to hold essentially any weight at its end, but that will need to perform thousands of repetitions (currently using MG 996R servos, but might ...
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0answers
80 views

Problem calculating inverse kinematics in a 4-DOF robot arm for drawing

I'm trying to do a robotic arm to draw a circle with 4-DOF, I'm using the Denavit-Hartenberg method (DH) to calculate the foward kinematics and the jacobian method to do the inverse kinematic. So ...
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1answer
33 views

What is meant by the phrase "movement positional jitter"?

I was searching online for the meaning of this statement but the closest I came across is that jitter here refers to some sort of "deviation". Therefore, if we say that the movement ...
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2answers
17 views

Generate robot model for openrave

Is there another way to generate a collada model to work with openrave other than converting an URDF file with ROS' collada_urdf software? The problem I'm encountering is with the setup needed to use ...
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0answers
27 views

robotic arm 6 dof with 3 kg payload [closed]

we are building 6 DOF robotic arm with a 3 kg payload and i don't know how to select a motor for that i am thinking of using a servo motor but which to use is the problem
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3answers
421 views

Robotic arm servo motor- Not enough torque

I require your help regarding a problem I’m encountering. I am a beginner in robot modelling. I am designing a robotic arm for agricultural use and I am having issues with the motors. I am using ...
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1answer
500 views

Extended Kalman Filter in robotics - Worth it?

I wonder if Extended Kalman Filter(EKF) is used in robotics, or is only Kalman Filter(KF) used in robotics. Kalman Filter is included in Linear Quadratic Gaussian(LQG) controllers. But how would EKF ...
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1answer
55 views

Dynamic analysis of a robot pedestal

I have to design a robot pedestal for a research project.The robot I choose is kuka KR 6 R700 6.In the datasheet is said all the forces/moments in worst case scenario.I did some FEA for the structure ...
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1answer
45 views

What network protocol/control units are motor-based robots controlled with?

I know most vehicles are controlled via CAN (Controlled Area Network) protocol through an ECU (Electronic Control Unit) which send/receives data using this protocol and then sends/receives Amps/Volts ...
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0answers
34 views

In MuJoCo why do some XML files have objects fall to the ground while others are just fixed above the ground?

Why do some models, or objects in a MuJoCo XML script fall to the floor while others don't? In the models files that come with the MuJoCo zip, the robot arm (arm26) does not fall to the ground while ...
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1answer
29 views

How to calculate DH parameters for Higher Pair?

I am trying to build a robot which is having Bevel Gears connecting two links. I want to calculate DH parameters, but i am stuck with this bevel gear as when the joint rotates both angle and ...
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1answer
35 views

Mobile robotic arm camera position

I'm working on my graduation project which is a mobile robotic arm that performs pick and place tasks. I wanted to know the possible ways to mount the camera where i can reach the desired destination ...
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1answer
20 views

Estimating distance between joint positions

I was wondering if there is any good way to estimate the difference between two joint states of a robotic arm. Currently I am using something like this: $\sqrt{\sum_i^N{(JStateA[i]-JStateB[i])^2}}$. ...
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1answer
110 views

Robot arm with steppers - speed

I am using a 5 axis Robot arm (Robolink robot from Igus) to perform some 3D printing routines. By now I am trying to use them and have him have some good position (and speed) control. The robot is ...
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1answer
321 views

UR5 Visual servoing(image based, eye in hand)

I am implementing IBVS on a UR5 using ROS. The algorithm works very well in linear X, Y and Z and omega Y. When I try to add a fifth axis(omega X or Omega Z), the robot jerks heavily and goes into ...
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1answer
85 views

Scara chess robot design for 3d printing

I have two question regarding a Chess robot. I want to build a Scara robot that could play chess on a 37 x 37 cm chess board, but I couldn't find any design that can cover the whole chess board and ...
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2answers
380 views

The Jacobian resulted from Screw method is different from analytical one (Example Inside)

I am currently solving a kinematics example that asks for the Jacobian. However, when I solve it using the Screw method I get different results from the analytical method, The example is kinda hard to ...
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1answer
22 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 ...
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1answer
48 views

What is the noise in this PWM signal?

I'm in the process of calibrating servos while constructing a new hobbyist robot arm. When testing the base rotation servo I noticed some unexpected noise in the PWM signal while the servo is in ...
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2answers
4k views

Designing a 5 bar linkage robot: Plot Clock

I am a beginner at robotics. I recently stumbled across this robotic clock on youtube. I am an electrical engineering student and am interested in submitting it as my minor project. I have studied ...
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1answer
49 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
38 views

Elegant way to mathematically relate joint positions (without a root/base joint) for easy re-rooting?

I'm pretty new to robotics, but have learned about the tranformation matrices and how to relate relationships between joints using transformation matrices. I just wonder if there is a system that ...
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50 views
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0answers
37 views

PID control for robotic manipulator servoing

I'm trying to enable robotic manipulator servoing using MoveIt servo implementation. However, I'm having some questions regarding reference following and error compensation. The thing is, I roughly ...
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0answers
16 views

Quasi Direct Drive Actuator - Slot & Pole Combinations for High Torque Motor

I am building my own Quasi Direct Drive actuator and looking for information/ design guidelines for building a High Torque Motor similar to the MIT Mini Cheetah below. Specifically I cannot seem to ...
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0answers
33 views

Jacobian row of zeros. Why?

I have a Simulink model that has a standard Simulink block that determines the Jacobian for a given Rigid Body Tree model. The Rigid Body Tree model is a built in model of the Franka Emika Panda robot ...
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2answers
61 views

Servo Starts Oscillating Under Disturbance

I'm using MG996R servos to control a 6-axis desktop robot arm. When no disturbance (like a gentle push to the robot), the servos are fine and can hold their places. But under a gentle disturbance, ...
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0answers
73 views

Solution to Inverse Kinematics of a 6 DOF Articulated robot with a wrist joint

I'm working on getting a solution to the inverse kinematics of a 6DOF Articulated robot with a wrist joint. I derived the robot's forward kinematics firstly, using these angles $$θ_1 = 60.102$$ $$θ_2 =...
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1answer
232 views

Controlling YuMi robot by serial port

I'm trying to control the YuMi robot arm by a serial port. The serial port will give the information on what direction the end-effector should move and what is the velocity. What I would like to ...
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1answer
35 views

Jacobian for transformation of rotation angles

It is known that with the help of the Jacobi matrix it is possible to transform the angular velocities of the drive links $\boldsymbol{\omega}$ into the angular velocity of the platform $\boldsymbol{\...
3
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1answer
26 views

Can inferences about servo torque or applied force be made by measuring servo current drain?

I'm working on a robot arm project for hobbyist / learning purposes. One of my DIY motivations is to be able to easily add additional sensors. I've been thinking about using ACS712 linear current ...
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1answer
85 views

Peter Corke Robotics Matlab toolbox Panda DH/MDH conventions confusion

I am new to this toolbox and DH parameters in general but I noticed that the Peter Corke Robotics Toolbox for Matlab originally contains a model of the Franka Emika Panda robot. This model was made ...
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1answer
149 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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0answers
56 views

How to correctly determine the θi Denavit-Hartenberg parameter for a SCARA manipulator?

I am using Tsai's Robot Analysis (The Mechanics of Serial and Parallel Manipulators) and I am working on deriving the homogeneous transformation matrices for the SCARA robot with the assigned frames ...
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1answer
156 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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1answer
35 views

How the motor commands are obtained from gcodes?

I have started my research with scara and cartesian robots for drawing robot. The gcodes are converted and given to robot. There are firmware like grbl, marlin, etc for this process. But I couldn't ...
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0answers
23 views

Obtain a State Space System given Denavit-Hartenberg parameters and a Rigid Body Tree model in MATLAB

I'm confused regarding the representatoin of a 6 D.O.F. robot arm with multiple links. I have the denavit-Hartenberg parameters and have used these to create a Rigid Body Tree model in MATLAB. The ...
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1answer
196 views

Controlling Actuated Robot Hand in Underactuated Manner

We have an allegro hand in our robot, and it is in actuated behavior. In other words, each joint is controlled one or more than one actuator, that is motor. There are 3 actuators for each finger, ...
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2answers
351 views

Tool calibration- orientation

I'm currently working on calibration of robot tool. I have found some simple methods to get the tool centre point. But I'm sure how to get the tool orientation wrt the robot's tip (the point where the ...
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2answers
458 views

Testing and Lifespan of Industrial Robots?

How does one go about testing the robot once it is built? How does one predict the number of hours it can operate? I see most of the industrial robots for instance robotic arms have warranty of 12-18 ...
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1answer
52 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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2answers
1k views

Finding correct RPY for approaching a known point on a plane

I have a robot with 6 DOF that I want to use to grab a hanging sheet at a specific point near its edge. The grip needs to be perpendicular to the edge and co-planar with the point of course. I have ...
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1answer
53 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
1k views

Poor accuracy of hand eye calibration when using vanilla Tsai's method

I’m working on the hand eye calibration for the robotic arm. I attached the camera near the tip of the robot (or end effector) and took around 40 pictures of an asymmetric circles pattern. I ...
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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 ...
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2answers
1k views

Jacobian of a 6DOF arm

I have a robot with 6 DOF. I read a lot of tutorial on how to compute the Jacobian, but usually all examples are for planar robots with 2DOF. I don't understand how can I get the Jacobian of a 6 DOF ...
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1answer
193 views

Robotic Manipulator 3-RRP v2

I recently asked a question about a 3-RRP manipulator but the only answer didn't work for my robot. I would describe the manipulator as an arm that rotates around the shoulder over the x-y axis, the ...
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2answers
73 views

Calculation of error, based on camera images

I am trying to measure the precision error of a gripper that is mounted to the flange of a 6 DOF industrial robot. The gripper-design is rather complex, therefore we would like to make sure it is ...

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