TL;DR:
Choose a simulator by what you want to do: learn robotics basics, practise with ROS, or test a specific robot.
Compare features, learning curve and community, then try two with the same small robot.
Gazebo and Webots are both free to try, and your robot description carries over better than you might fear.
You have decided to try simulation, and now there are a dozen options. Every one of them can drive a box on wheels around a floor. The useful question is not which is best in general, but which gets you from install to a robot that moves with the least pain.
What you need from a simulator
A beginner needs five things. A ready-made world and robot to start from. A way to add a sensor such as a camera or LiDAR. A way to control the robot from code you write. Reasonable accuracy for wheels, collisions and friction. And enough documentation that your error message has been seen by someone else.
If you already know you will use ROS, check how well each simulator connects to it, because that decides how much glue code you write.
The three things to compare
Features. Which sensors, robot types and physics options are built in? Can it model a differential drive, an arm, a drone?
Learning curve. How long from install to first moving robot? How many files and tools must you learn?
Community. Are there tutorials, forum answers, example robots and recent activity? A smaller feature set with a big community often beats the reverse.
Worked example: Gazebo vs Webots for a two-wheel robot
The test robot is a two-wheel differential drive: two driven wheels on one axle and a caster for balance. It has a LiDAR on top. The goal is to drive it toward a wall and stop 0.5 m away. Both Gazebo and Webots are free to try, so the comparison costs only time.
Question | Gazebo | Webots |
|---|---|---|
Typical setup | Describe the robot in a file such as URDF or SDF, run it with the simulator, and connect through ROS bridges | Build the robot in the editor or a proto file, and write a controller that runs inside the simulator |
ROS link | Designed to be used alongside ROS and widely used with it | Supports ROS through an interface package |
First-hour experience | More pieces to install and configure, more transferable to ROS projects | A shorter path to a moving robot with sample worlds and controllers |
Sensors | Cameras, LiDAR, IMU and others through plugins | Many sensors built in with ready examples |
Where to ask | Large robotics community around ROS | Active forum and good documentation |
Do the stopping task in each and time it. The control logic is the same: read the front LiDAR distance d, and command forward speed only while d > 0.5. For a forward speed of 0.2 m/s starting 3 m from the wall, the robot needs to cover 3 − 0.5 = 2.5 m, which takes 2.5 / 0.2 = 12.5 s. Both simulators should show it stopping near 12.5 s of simulated time, with some overshoot because the robot cannot stop instantly.
Check the overshoot by thinking about braking. If the robot decelerates at 1 m/s² from 0.2 m/s, the stopping distance is v² / (2a) = 0.04 / 2 = 0.02 m, or 2 cm. If it stops 10 cm late, check the control loop rate and sensor delay, not the simulator.
What you learn from this is rarely a winner. It is a feel: one tool may suit a classroom-style, script-first approach, the other a ROS-first workflow. Which one clicks with you is data.
Where it goes wrong
Choosing for the demo video. A pretty rendering says nothing about how smoothly your own robot will run.
Tutorial mismatch. Tutorials written for one version may not work on yours. Match versions before blaming yourself.
Weak computer. 3D simulation needs graphics and memory. If it is slow, simplify the world or lower the rendering detail.
Starting with a complex robot. Begin with two wheels and one sensor, then grow.
Wrong physics settings. If a robot drifts or jitters, check masses, friction and step size before changing the code.
How real robots use it
Teams pick a simulator for their stack and then keep it. A ROS-heavy lab will usually choose one that plugs straight into ROS; a teaching lab may choose one with a shorter path to a running robot. Whichever you choose, the robot should be described in a portable file, for example in URDF, which describes a robot so software can use it, so you can move later.
Try it yourself
Pick two: Choose two simulators that run on your computer and are free to try.
Use the same task: Drive the same two-wheel robot to stop 0.5 m from a wall in both.
Keep notes: Write down time to install, time to first motion, errors you hit and how fast you found answers.
Decide: Stay with the one where you spent more time on the robot and less time on setup.
Frequently asked questions
Do I need to know ROS first?
No. Some simulators can be driven from a plain script. Learn ROS when you want robot software to be split into parts, as in the article on how ROS connects robot software.
Will my robot model work in another simulator?
Often with some changes. Keep the description clean and the numbers honest, and most of the work carries over.
Get started
