# Questions tagged [velocity]

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### Pid controller with encoder feedback for tank steering

I'm struggling to find a solution for my problem. I would like to write a simple PID controller in C/C++ that accepts a speed in RPM and controls the motors by receiving the feedback from the encoders....
16 views

### Nav2 how to smooth velocities with deadband?

I'm having trouble with the cmd_vel that nav2 gives me for my robot. The robot only moves with : angular speeds ∈ [-1rad/s, -0.3rad/s] ∪ [0.3rad/s, 1rad/s] linear speeds ∈ [-1.2m/s, -0.3m/s] ∪ [0.3m/s,...
11 views

### Output of JointGroupVelocityControllers on PR2 robot_mechanism_controllers

I am on my way to understand the behavior of the JointGroupVelocityControllers used on PR2 robot mechanism controller. When using this controller to execute the ...
182 views

### Real time velocity control with Moveit

I am working on a research project involving robotic welding, and once I get the motion plan with moveit, I want the end effector to move in specific velocity along the weld path, based on camera ...
25 views

### Probabilistic Robotics by Thurn: Velocity motion model. Detailed derivation for eq. 18

In the book, The equation for finding center of circle is denoted in eq. 5.17, which is as \begin{pmatrix} x^* \\ y^* \end{pmatrix} = \begin{pmatrix} x \\ y\end{pmatrix} + \begin{pmatrix} -\lambda \...
29 views

### What is the kinematic model of a quadrotor/quadcoptor with an X configuration?

I would like to know what is the kinematic model of a quadcopter in X-configuration. Basically I want the relation mapping rotor speed to the body twist (or body frame velocity). ...
• 21
1 vote
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### Inquiry about Zed 2i ROS Wrapper: Velocity Parameters for Object Detection

Hello Robot Stack Exchange community, I am currently working with the Stereolabs Zed 2i camera and its ROS wrapper for object detection. I have been exploring the codebase on GitHub and reviewing the ...
• 25
1 vote
111 views

### 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....
25 views

### Navigation odometry and velocities published

So why do I have to calculate the VX and VTH for odometry when move base from navigation stack actually publishes the velocities for my robot ... i don't get that can someone plz explain. ...
18 views

### Confusion in how to start solving such problems

A coordinate frame (2) is attached to a body with origin 02 at the position [x(t) y(t) z(t)] transpose from the base frame (1). Apart from translation. the frame is rotating about the x1 axis by an ...
29 views

### Turtlebot3 stop accepting /cmd_vel command

I am using Cartographer for Mapping in Turtlebot 3. I've done half mapping and the Turtlebot stop moving the cmd_vel is publishing the data but bot is not moving
32 views

### Use differential drive controller to publish velocity

Hello, first of all, for a bit of context : I'm using Ubuntu 20.04 with ROS Foxy and Gazebo 11 (I think) I'm still learning ROS so I might be inacurate but I'll try my best! I'm building a simulation ...
108 views

### Settings for max velocity and acceleration not effected at real FANUC robot

I am using the the python commands set_max_acceleration_scaling_factor(x) and set_max_velocity_scaling_factor(y) of the ...
59 views

### How to change the output of a /cmd_vel topic?

Hi, I'm currently working on a project with a BlueRov2 and I measured the global speed (with motion tracking cameras) of the ROV for different input in the /cmd_vel topic and now I have the equation ...
14 views

### Industrial Robot Client sends wrong velocity on last waypoint?

Abstract: Created a plan to rotate single joint from 0 to pi/2 radians. Examined plan looks fine with smoothly tapering velocity, however, actual robot motion ends with accelerated jerk at end. ...
26 views

### Velocity and acceleration scaling

Hi, I'm not sure if this is the correct place to this question, but anyway I'm going to ask it in this forum. I'm controlling an UR10e robot with MoveIt and ROS, and I realized that the controllers ...
20 views

### My node doesn't publish to the topic cmd_vel

I created a node in order to move the robot and rotate it but it seems that the node doesn't publish to Twist can anyone help ? this is my code ...
3 views

### Publishing Velocity of Kalman Filtered Clusters

Hello everyone, I've segmented an incoming Point Cloud, applied an euclidian cluster extraction and then associated the data between frames combined with a Kalman filter. Right now I'm publishing text ...
24 views

### Looking for an industry robot with joint velocity control

Hey All, Currently we are looking for an industry robot that accepts joint speed command for real-time force control. I know Universal Robot is a potential candidate. However, its payload is not ...
5 views

### what is a y-axis in /joint_states/velocity[5] in rqt_plot?

hi . in rqt_plot => /joint_states/position[5] The x-axis is time in seconds and the y-axis reflects joint position in radians . but what is a y-axis in /joint_states/velocity[5] in rqt_plot ? ...
3 views

### Ros Canopen PositionJointInterface working with mode 3?

Hi, I try to control my robot arm by ros canopen but the driver do not have Interpolated Position Mode which is mode 7. I follow the canopen_test_utils example and it use mode 3 for position ...
20 views

### Teb Local Planner : Increasing x linear velocity

Hi, I'm currently using the teb local planner for a tricycle robot and it gives good results but I would like to i Increasing the max_vel_x parameter doesn't seem to change the speed and I am having a ...
8 views

### Velocity controll and PID tuneing

I'm currently building a simulation model for my robot and so far almost every thing works. I can move all my actuators. I'm currently stuck with the controlling the wheel velocity. I have a joint <...
24 views

### Turtlebot wont move (MATLAB)

Hi I'm trying to run some very basic code to move my turtlebot. i am using ROS Indigo on Ubuntu 14.04.2 I am communicating through MATLAB and I should have everything setup fine(keyword should). ...
30 views

### How to plot position(x y z) and velocity of fixed frames(end-effector) in rqt?

hi . i need answer to complete my Master's thesis. i want plot position and velocity of end effector that have fixed joint using rqt. How to plot position(x y z) and velocity of fixed frames(end-...
22 views

### Delay incoming messages

Is there a way in Rospy to delay incoming messages? Specifically, I wish to delay incoming velocity commands for teleop. I can't use a sleep because I still need my program/node to run other processes....
5 views

### epos_hardware_node can't find parameters

Hey, i tryed to get the epos_hardware package ti work. I have the right parameter in the yaml file and if i started the launch file directly with ...
2 views

### Is there an existing speed control node to connect the robot_localization state estimator with the diff_drive_controller?

I am using ROS Indigo on a differential drive robot for indoor use (no GPS). The path is pre-determined and the velocity along the path is to be controlled. I believe that move_base node would be ...
31 views

### Problem publishing at cmd_vel

Hello, I have written the following code so I can send commands to my robots motors, which are listening to the /labrob/cmd_vel topic: ...
5 views

### Examples of closed-loop body-frame velocity controllers for a mobile base

Are there any examples of closed-loop velocity controllers for mobile robots? I'm referring to a node, or even a robot-specific function, that takes in: a desired velocity command (e.g. from nav ...
12 views

### How can the velocity of a robot be found if we have VICON coordinates available?

I have coordinates of the robot available using VICON motion capture system. How can they be used to find the velocity of robot at each instant? Originally posted by Ros User on ROS Answers with ...
60 views

### Computing Odometry from two velocities

I am looking to determine how to compute odometry for my robot. It is a skid-steer platform with one motor on each side (left/right) and each side reports an RPM which is then turned into a velocity. ...
22 views

### Best way to use Moveit for teleoperation?

I've seen this topic discussed a bit here, and on the MoveIt! mailing list here and here, but those conversations are pretty old now and I'm wondering if there is a clearer answer now. I have a 7 DOF ...
12 views

### How to command velocity in MoveIt!

Hello, I'm trying to command an arm in MoveIt! using a 3D mouse. I'm not working with real hardware, or gazebo, its all using MoveIt! So far I am able to get the current joint positions of the robot, ...
25 views

### What is the difference between acceleration and effort?

In ros_control what is "effort"? How is it different from acceleration? Can I use a value meant to be acceleration in place of effort? For context I'm using moveit and ros_control with a ...
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### Velocity smoother and navigation stack

Hello , I am working on a project with clear-path husky and i am trying to get velocity smoother and navigation stack to work together. Any advise or suggestions to make it work? Thanks Originally ...
45 views

### URDF velocity limit, how it works?

Hello! I've taken the 06-flexible.urdf model from the urdf_tutorial package, and I've added the lines to set a velocity limit on the head_swivel joint into the urdf file. http://wiki.ros.org/urdf/XML/...
21 views

### How to improve the speed of dwa in base_local_planner?

I am using base_local_planer as local planner. However, with same parameters, the speed of robot from Dynamic Window Approach(DWA) is smaller than with Trajectory Rollout(TR). The "max_vel_x&...
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### How can I check the time response of my model in Gazebo?

Hi Ros users! I would like to know the time response of my model P3DX in Gazebo. I am going to explain it: I am using ROS indigo, Gazebo2 and linux 14.04. I have a model P3DX (ua_p3dx_pkg). When I ...
52 views

### How to send velocity to pixhawk with Mavros?

Hi guys, after searching a lot and don't get a solution I would like a help. I am a new user of Mavros package and I have some doubts about it. My setup for tests is: 1 Pixhawk with ArduCopter V3.2....
30 views

### Move a certain distance (geometry_msg:Twist)

Currently this is the code that I have, and I am able to get the robot moving by editing the linear x or angular z values (speed). ...
44 views

### UR5 velocity control and trajectory recording/replaying

Hello everyone, I have the following two issues to solve: #1 I would like to control the velocity of the path execution of the UR5 robot. At the moment, I'm using the UR5 ROS-Industrial driver and ...
5 views

### NavStack Robot Moves Backwards

Hi Folks, When my robot is trying to avoid an obstacle, it tends to move backwards. How can I disable that option so that the robot only have forward velocity, and rotational velocity? Thanks ...
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### Turtlebot Linear Y has no response

Hi, I am trying to do Turtlebot Simulation. I am giving Linear x & Linear y . But it seems like linear Y has no effect. Then i tried below simple code to check linear y effect. after code run ...
81 views

### How to implement velocity transformation?

Hi all, i have the velocity topic /cmd_vel, and it's the type geometry_msgs::Twist, it is given in the object reference frame, and now i need to transform the velocity to another frame, such as my ...
77 views

### Subscribe and publish velocity

Hi, I have a code where I want to see the linear velocity of a powered wheelchair and then publish linear velocity to it. An example of the code is: ...
6 views

### very fast rotation

hi, all, my robot is rotating very fast. it runs on move_base. although I have capped the rotation as below in the local path planner and rotate recovery ...
7 views

### Limit linear velocity

Hi everyone, I wrote a node that subscribes to the topic sensor_msgs/LaserScan and publishes in the topic geometry_msgs/Twist. I want to limit the maximum linear velocity that a powered wheelchair can ...