# Revision history [back]

### DRCSIM: simulation slows down as robot moves.

This is for Gazebo 1.4, drcsim-2.1. Worth testing on Gazebo 1.5, drcsim-2.2

The simulation slows down as the robot is "driven" through a complex environment.

Here is a simple test everyone can do at home:

In terminal window #1

source /usr/share/drcsim-2.1/setup.sh


press 'run' and wait more than 10 seconds for the robot to become unpinned.

In terminal window #2

source /usr/share/drcsim-2.1/setup.sh
rostopic pub /atlas/set_pose --once 'geometry_msgs/Pose' '{position: {x: 3.0, z: 0.95}, orientation: {z: 0, w: 1}}'
rostopic pub --once /atlas/cmd_vel geometry_msgs/Twist '{linear: {x: 1}}'


On a dual Intel(R) Xeon(R) E5-2687W @ 3.10GHz with a Quadra 6000 and a Tesla K20 GPU: The simulation starts with the Real Time Factor around 0.92. By the time the robot reaches the first turn it has declined to 0.36.

On a i7-3770K @ 3.50GHz with a GTX 690 and another i7-3770K with a GTX 650 GPU: The simulation starts with the Real Time Factor around 1.0. By the time the robot reaches the first turn it has declined to 0.14.

There is no sign of any rebound of the Real Time Factor if I leave the simulation running, having stopped the robot motion.

This slowdown does not appear to happen when using our own walking code.