# Tag Info

Accepted

### How do people create complex models/worlds in the Gazebo?

Those kinds of models are made in CAD software, exported to 3D rendering software to apply textures, and then imported in Gazebo. Or they are generated in some other way, e.g. through photogrammetry. ...
• 2,139
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### What is a Velocity Smoother?

The velocity smoother part of the code is this: ...
• 6,682

### What's the diffrence between $H_2$ and $H_\infty$ control?

In short answer: yes Kalman filter is a special case of an $H_2$ observer Yes Yes ... LQG is just Kalman filter + LQR controller, which are both special cases of $H_2$ Depends on the use case. $H_2$ ...
• 2,814
Accepted

### Meaning of a negative step response with quaternion

Welcome to Robotics, PaoloH! This is a fantastic question for Robotics - It has some Matlab/Simulink, some control theory, some spatial (quaternion) representations, etc. Robotics is the place to come ...
• 15.9k

### Dynamic torque simulation for a 6 DOF robotic arm

The dynamics of robotic arms are fairly complex, especially when there are more than three joints to consider. The problem is that the movement of each joint moves all the links beyond it, which can ...
Accepted

### Suggestion for relevant non-complex simulator

just use matlab or and python with a set of fixed features in space represented as points. Don't do any vision processing. At this point any vision processing would be overkill. you are making this ...
• 1,853

### AWS Robomaker - success story?

I'm a product manager from the AWS RoboMaker team. We have a tutorial that can help you get started with the service: Projects on AWS: How to Train a Robot Using Reinforcement Learning with AWS ...
• 41

### Solving pseudo inverse of Jacobian in Matlab/Octave

After running your code, it looks like everything is behaving how you have defined it to. The problem you are running into has more to do with the Jacobian itself and less to do with any mistakes you ...
• 904
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### Gazebo crashes immediately - Segmentation fault (Address not mapped to object [0x220])

It works using QT_QPA_PLATFORM=xcb gz sim
Accepted

### Is Robust Control and robotics well applied together?

Robust control is used for when you know that parameters are going to fall within particular bounds. For example, for a mass-produced robot arm, the arm masses fall between X and Y, the moments of ...
• 15.9k
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### Multiple robots in ROS Gazebo SITL with separate MAVlink/MAVproxy codes

I feel like I'm having to do a lot of work to understand this question. You are trying to simulate two vehicles, and... what's the issue? You are trying to simulate them in Gazebo, right? Have you ...
• 15.9k

### Dynamic torque simulation for a 6 DOF robotic arm

I think you may be going about this problem wrong. If you find a simulator that reports joint torques, then what? Are you going to iterate through every possible start and end location? You should ...
• 15.9k
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### Roy Featherstone toolbox robot model

I changed the code and now it works properly. ...
• 99

### What Software Is Used For Autonomy Software Simulation?

There are quite a lot options for this, each with different features, strengths and weaknesses. A few examples: Gazebo (as mentioned by edwinem): very well known in the robotics community, some would ...
• 131

### Data collected from ROS

As Ben noticed, you may want to elaborate on your question, but in general data collection in ROS is performed using tools from the rosbag package. As you'll find when you read the documentation, ...
• 1,363
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### My Pick and Place Program Not Working

The best way to debug geometry related applications is by using plots. First of all, plot the initial configuration, with robot TCP, cube initial position, cube final position. As these are all input ...
• 6,682
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### I'm looking for a simplified control scheme for a game-rendered robotic arm

If I understand correctly you are not looking for a control scheme, you are tryin to solve the (inverse) kinematics problem. In robotics, kinematics is preoccupied with motions, disregarding forces. ...
• 6,682

### Drone Development using ROS Noetic on Ubuntu 20.04

It appears that the package you're looking for is available in noetic: https://index.ros.org/p/jderobot_drones/#noetic If you're getting that error it's likely that you have not setup the ROS package ...
• 25.3k
Accepted

### How to program to generate robot URDF(Serial manipulator) when having stl file of each link with Python

Thank you,Now I have found odio_urdf library that can generate urdf by programming in python like you code in urdf file.

### Simulate Wind in Gazebo - physics_msgs

You don't have to compile these files with your plugin. You should include the already existing wind plugin in to your world file. Check this example file and how ...
• 86
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### Programmatically set joint friction in Gazebo Fortress (previosly Ignition Fortress)

You are correct that gz-physics doesn't yet have a Feature for setting these properties at runtime. I've opened a feature request to implement it in gz-physics#449. A similar Feature was requested for ...

### How do people create complex models/worlds in the Gazebo?

There are scripts for various tools that automate the generation of an SDF (you may need to adjust/fix some parameters afterwards). Due to Gazebo's backwards compatibility for older SDF versions, ...
• 468

### Generate synthetic accelerometer data based on (x,y,z) coordinate

I assume that the three location input signals are functions of time, i.e., $x=x(t)$, $y=y(t)$, and $z=z(t)$ relative to a fixed, non-rotating reference frame. Then one could create a simple ...
• 385

### Ackerman steering model

I am not sure if this is what you are looking for but the simplest odometry equations for ackermann steering go as follows: ...

### Error in simmechanics matlab while doing inverse dynamics using custom joint

SimMechanics isn't an "inverse dynamics" engine, it's not an inverse kinematics engine, it's a "forward dynamics" or just "dynamics" engine. You provide link dimensions, inertias, and joint ...
• 15.9k

### Error in simmechanics matlab while doing inverse dynamics using custom joint

I solved this problem by seeing below image from internet. This image explain the constraints in coordinate system in simulink. R = revolute ; S = spherical; W = weld; P = prisimatic As I have ...
• 385

### Robot Arm Simulation

How should be achieved the arm's rotation properly? In unity each game object has a transformation property. The rotation component of the transformation property has to be changes in order to rotate ...
• 6,682

### Validation of dh parameters

I'm not a fan of DH parameters but they are entrenched in robot kinematics. An approach I prefer is to just write the whole chain as a series of simple transformations, eg. Ry is a rotation about the ...
• 1,712
Accepted

### Validation of dh parameters

The easiest way to validate a set of DH parameters is to plug them directly into a simulator which can build a robot model from a DH table. Once you've got the DH-generated robot model, you can verify ...