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 ...
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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 ...
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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 ...
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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 ...
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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....
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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 ...
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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 ...
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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 $l$ $...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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:
...
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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
...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 '...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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/...
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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 ...
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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^...
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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 ...
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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?
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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}(\...
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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 ...
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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 ...
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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 ...
