# 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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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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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: $\sqrt{\sum_i^N{(JStateA[i]-JStateB[i])^2}}$. ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
50 views

### how to solve inverse kinematic of 7-dof va1400 who has three offset configuration (shoulder elbow wrist)

va1400 kinematica model by Peter Corke MATLAB RVC-toolbox v9.10 ...
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 ...
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 ...
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 ...
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, ...
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 =...
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 ...
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{\...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...