Questions tagged [control]

A method or device to manage, command or regulate some part of a system.

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Why is admittance control better than impedance control for huma robot collaboration?

I have seen many papers that use admittance control for human robot collaboration but no one tells why admittance is the choice and not impedance. Is it something very trivial that I should know or ...
Shubham Kumbhar's user avatar
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Moveit_servo with ur_modern_driver

I have been working on a UR10 (older version, thus using ur_modern_driver) for pick and place movements. However for a specific case I want to change to smooth servoing towards an object based on ...
LucasMS's user avatar
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Mambo parrot /tello control propeller speeds

From my understanding, for parrot mambo and tello drones, we control forward-backward, up-dow, left-right, and yaw speeds (in m/s and deg/s). But the low level control is control the 4 propeller ...
Jose Daniel's user avatar
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Creating a Custom Hardware Interface for a Two-Wheeled Mobile Robot for ros2_control?

I am in the process of developing a custom two-wheeled mobile robot with differential control, and I want to integrate it with the ROS 2 ecosystem, specifically leveraging ros2_control. I understand ...
Robotawi's user avatar
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End effector velocity control of a 6-DOF robotic manipulator using MPC

I've been trying to utilize Model Predictive Control (MPC) scheme that I have for end-effector position reference $x(t)$ tracking control to build end-effector velocity reference $\dot{x}(t)$ tracking....
HOJUN LEE's user avatar
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How do I send a new position to my 5 dof robot arm?

I am a newbie with ros2 control. I am using ros2 iron on Ubunto 22.04 (Linux Mint). I made a copy of the ros2_control demo example #7. This is the one that is launched with the command ...
Jeffrey Edward Messikian's user avatar
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42 views

What are the gain and bias parameters used to control actuators?

When I read the Mujoco official document, the following paragraph raises my confusion: Different settings of the gain and bias parameters can be used to model direct force control as well as position ...
KKKmelody's user avatar
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Controlling motion of single link

This seems like it should have been a well studied problem, but I can't find any solution. We want to define what a motor must be commanded to do to move a single link with mass $m$ and length $l$ $...
guero64's user avatar
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Best practice for logging callback durations and execution times in ROS

I'm wondering if there are any best practices for logging callback durations and execution times in ROS? As my system evolves and implementation is changed, I'd like to be able to monitor the ...
woodwardsquidward's user avatar
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How to visualize panda robot in gazebo while moving it with my own cpp script

So I'm using franka_ros where I added my own package that includes some scripts that executes a trajectory for the robot using robot.control class from libfranka. I ...
mikel lasa's user avatar
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Which controller from `ros2_control` is appropriate for firmly grabbing a box with a 1-DOF gripper in Gazebo Classic?

I want my robot arm (Turtlebot3 with OpenManipulator-X) to firmly grab a box, however the gripper does a sudden close movement and the box flies away. Is a firm closing movement possible with ...
geko's user avatar
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Transform between odom and base_link is faster than in real life [Solved]

i have a differential drive mobile robot and i want to add him the navigation and the localization satck. Currently it's controlled by a teleop. But when i look the transform between odom and ...
Josselin's user avatar
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90 views

Steer to a pose for a differential drive robot

I am working on a diff-drive robot that needs to go and dock into a docking station to charge when the battery is low. The charging socket is on the back of the robot, like a vacuum cleaner, so this ...
ssarkar's user avatar
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Gazebo not running when I try to load STL files

I have an issue with Gazebo, when I try to load my URDF file (including STL meshes), Gazebo crashes. This is my URDF file: ...
user35808's user avatar
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simple hardware interface for mobile robot (RobAir)

I want to create a hardware interface to interface a simple research mobile robot called RobAir, this robot has two wheels and using velocity controller cmd_vel through a ROS node on Arduino board to ...
Bilal's user avatar
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Resources for precision aiming, trying to aim camera long distance

I'm looking for resources online regarding precision aiming of a camera at a target that is far away. I'm a neophyte here, and I was hoping to see what kind of mechanical designs people have had and ...
mj_'s user avatar
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Does the ros2_control's JointGroupPositionController handle velocity constraints?

In ROS 1, you could limit the speed that the position controller moved at by specifying a <limit> tag within the ...
DLu's user avatar
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robot not moving left or right

I am building a 4 wheel differential drive robot. The robot is not moving left or right in gazebo, although it is moving forward and backward. The robot is moving completely fine in rviz2(forward, ...
KalaDaku's user avatar
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How to reduce the turbulence of a robotic arm, when it's end effector touches a surface?

I am working on a project related to tele-robotic ultrasound where I have to tele-operate a virtual UR5 robotic arm with a end-effector(a thin rod) through a haptic device in PyBullet. When I make the ...
RaMathuzen's user avatar
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Enhancing Accuracy of Mars Rover Current Measurements through Mechanical Isolation of Sensors

The current sensor of the Mars Rover made by our university students team is showing unstable current measurements due to vibrations in the terrain. How can the sensor be mechanically isolated to ...
Furiounibu's user avatar
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ros2_control: No parameter file provided. Configuration might be wrong. failed to parse input yaml file(s)

I am trying to build a 4 wheel differential drive robot. But i am getting error when using ros2_control. Version: Ros2 Foxy Terminal Output ...
KalaDaku's user avatar
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169 views

Joint Trajectory Controller: Joints on incoming trajectory don't match the controller joints

I am trying to create a script to control my robot using an action. The action server was already created by Joint Trajectory Controller and I had to make the action client. The issue I am having is ...
Fischdog24's user avatar
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59 views

How to keep the orientation of end effector during movement in ROS Gazebo simulation

I am using Ubuntu 20.04, ROS NOETIC, Moveit to control a UR5 robotic arm in Gazebo simulation. I am trying to move a robot with a fixed orientation of its end-effector. The basic idea is to use the ...
walter wang's user avatar
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My link starts to levitate in gazebo

I'm developing a gazebo robot and I have an upper torso (upper_body_link) that needs tilting (with revolute joint 'upper_body_joint'). the problem is that when running the launch file in the gazebo ...
Rui Silva's user avatar
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How to compensate integral anti-windup in PID temperature controller with current limiter?

I have a PID temperature controller that outputs a voltage to heat the system up and I would like to add current limiter as I assume I don't know the resistance of the heater. The PID controller has ...
grxty_'s user avatar
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1 answer
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Developing a robot using mecanum wheel to follow specific path accurately

I am developing a robot using esp32, mecanum wheel, stepper motor and mouse sensor. The robot runs 1000mm forward, 10mm sideways (right side without turning), 1000mm backward, 10mm right and cycle ...
Sem's user avatar
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1 answer
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How are exoskeletons controlled?

It is my understanding that there are 3 fundamental control methods : velocity, position and torque. In exoskeletons meant to augment an healthy user's strength, a typical control method used is ...
Kristof's user avatar
2 votes
1 answer
93 views

What’s this gearbox called? [closed]

I took an apart a child’s toy because it looked like it had a neat gearbox in it, it did. The problem is I have no idea what type of gearbox is and I wanna see more things used with it. It rotates ...
Ivan Gloss's user avatar
2 votes
1 answer
70 views

How do you calculate this integral term in this PI Controller Formula?

This formula is the PI Control given in Eqn. 11.6, Pg. 419 of Chapter 11 in book Modern Robotics by Kevin M Lynch and Frank C Park. Here, Vb is the twist ==> Vb = (angular velocity, linear ...
Shravan's user avatar
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Inverted pendulum LQR controller using motor

In my lab, I am trying to balance an inverted pendulum using simple LQR. To balance the arm I am using a DC motor. Now I have the A, B, C, D matrices. Using those I am able to find the feedback gain '...
V Adarsh's user avatar
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How to exchange commands and states between hardware interfaces (to generate a CAN message)

I have a robot with ackermann steering and front 2 wheel drive. The vehicle already has all the mobility controls executed by the ground mobility module. The autonomy layer (the computing unit) will ...
guidout's user avatar
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2 votes
1 answer
127 views

How to control the position of a load shared between two (servo)motors?

I want to position-control an axis combining the action of two DC servomotors - one of them alone is not powerful enough; I had those available and preferred not to buy a new one. I have not the ...
temporary_pigeon's user avatar
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1 answer
69 views

Steering wheel angle control

I am working on an autonomous vehicle's control, specifically the steering angle control. Knowing that I used kinematic bicycle model, my questions are: How do I choose the actuator for my steering ...
Asmaa GZ's user avatar
1 vote
3 answers
120 views

How do I calculate reference trajectory for a robot following a parabolic path at a constant speed?

I have a 3 DOF robot arm and have been tasked with making it follow a path of $y=6-x^2$. Normally to compute the reference trajectory, I would simply create a linearly spaced vector of $x$ values and ...
Daniel Ogden's user avatar
2 votes
1 answer
142 views

Velocity control with position setpoints

I'm trying to control the toyota HSR with a higher level whole-body controller that computes velocities, but the robot only offers JointPositionInterfaces in it's ros_control HardwareInterface ...
student's user avatar
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1 answer
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Derivative Block Diagrams

I am a newbie in Control Theory. I am solving an exercise found on-line. I do not expect anyone to solve it for me. I would just ask for a clarification about the block "p+a". I suppose it ...
Gino's user avatar
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1 vote
1 answer
87 views

Webots - Copy Paste a Robot

In Webots: I want to do a Predator/Prey simulation and need to spawn the exact same robot when an event occurs. How do I copy/paste a robot I have in my world scene tree. I build it my self therefore ...
HackMack's user avatar
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1 answer
347 views

Where should I write and call GPIO port connection in the hardware interface in ros2_control for control of robot movement on Raspberry Pi 4?

I am using ROS 2 Humble on Raspberry Pi 4(Ubuntu 22.04 OS). I am trying to build 2-wheeled diff-drive mobile robot and using ros2_control for controlling, but I'm ...
Shah's user avatar
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1 answer
73 views

Ros control pid gives different input than expected

I am trying to match the trajectory i am getting from gazebo simulation using ros_control and matlab for a simple pendulum which rotates in the horizontal plane (so no gravity, no friction and no ...
MIKE PAPADAKIS's user avatar
1 vote
0 answers
69 views

PD control with gravity compensation

Given the robot dynamics of the form $$M(\theta)\ddot{\theta}+C(\theta, \dot{\theta})\dot{\theta}+G(\theta)=u$$ where the notations have the standard meaning ($M$ is the inertia matrix, $C$ is ...
The Limit Does Not Exist's user avatar
1 vote
2 answers
29 views

How to compute orientation error for a Puma end effector

i hope that you'll be ok! I'm trying to control a Puma robot using the inverse kinematics in Matlab. I used unit quaternions to express the orientation of End Effector frame and orientation of desired ...
AleB's user avatar
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1 vote
1 answer
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When express a first-order system as a block diagram with feedback?

I've seen in many places that a first-order system is depicted as a block diagram using an integrator. For example, this figure comes from https://www.tutorialspoint.com/control_systems/...
rhody's user avatar
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Light weight one axis hinge name/recommendation

I'm attempting to build a crow that can stay upright even when its perch tilts. For that I need to have some single axis hinges (not u-joints). I'm using 3mm rod for my internal supports and am ...
Oldmicah's user avatar
1 vote
1 answer
77 views

Differential Inverse Kinematic Controller ROS

Inverse differential Kinematic - Problem with Orientation Hey guys, currently I am working to control my UR-Robot. My goal is to control the robot with inverse differential kinematics : 1.) vel_q = J^...
Student8759's user avatar
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1 answer
65 views

How to calculate Exponential coordinates of end_effector from Transformation matrix

I want to know Exponential coordinates of end effector $\text{S}\theta$(6-vector) from end effector transformation matrix. I calculated the transformation matrix of the end effector from the forward ...
HARCO's user avatar
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MPC over a distribution of states

What are the approaches to MPC when you have a distribution over your current state along with the process model?
FourierFlux's user avatar
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34 views

Question about Impedance control in The Modern Robotics: Mechanisms, Planning, and Control

Impedance equation In 11.7.1 section $\tau = J^T(\theta)(\hat{\Lambda}(\theta)\ddot{x}+\hat{\eta}(\theta,\dot{x}) - (M\ddot{x}+B\dot{x} + Kx))$ is actually means $\tau = J^T(\theta)(\hat{\Lambda}(\...
HARCO's user avatar
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3 votes
1 answer
76 views

Impedance control algorithm in The Modern Robotics: Mechanisms, Planning, and Control

I am studying The Modern Robotics: Mechanisms, Planning, and Control (by Kevin Lynch, Frank Park and Evan Suma). I am trying to implement Chapter 11.7.1 Impedance-Control Algorithm of the book with ...
HARCO's user avatar
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1 vote
1 answer
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How to use Supervisor along with regular libraries

In my Webots simulation, I am trying to use a supervisor in order to get parameters from other nodes to then have a motor respond by increasing or decreasing its torque, to which I have written the ...
Jonathan Callejas's user avatar
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1 answer
29 views

Recording controller output

I am a new to the field of control systems. In real life systems, such as process industry or continuous manufacturing, where large number of feedback control loops are present - is controller output ...
user1889930's user avatar

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