A robotics simulator is used to create embedded applications for a robot without depending physically on the actual machine, thus saving cost and time. In some case, these applications can be transferred on the real robot (or rebuilt) without modifications. The term robotics simulator can refer to several different robotics simulation applications. For example, in mobile robotics applications, behavior-based robotics simulators allow users to create simple worlds of rigid objects and light sources and to program robots to interact with these worlds. Behavior-based simulation allows for actions that are more biological in nature when compared to simulators that are more binary, or computational. In addition, behavior-based simulators may "learn" from mistakes and are capable of demonstrating the anthropomorphic quality of tenacity.
One of the most popular applications for robotics simulators is for 3D modeling and rendering of a robot and its environment. This type of robotics software has a simulator that is a virtual robot, which is capable of emulating the motion of an actual robot in a real work envelope. Some robotics simulators, such as Robologix use a physics engine for more realistic motion generation of the robot. The use of a robotics simulator for development of a robotics control program is highly recommended regardless of whether an actual robot is available or not. The simulator allows for robotics programs to be conveniently written and debugged off-line with the final version of the program tested on an actual robot. Of course, this primarily holds for industrial robotic applications only, since the success of off-line programming depends on how similar the real environment of the robot is to the simulated environment. Sensor-based robot actions are much more difficult to simulate and/or to program off-line, since the robot motion depends on the instantaneous sensor readings in the real world.
EZPhysics: Combination of Ogre3D and ODE physics, GUI exposes all of ODE's objects data, network closed loop remote control optionally via Matlab/Simulink.
Gazebo: Probably the most complete open source simulator to this writing. Unless the deb precompiled package is used, it is notoriously difficult to install. It started as part of the Player project but is also used in ROS.
Khepera Simulator Apparently before Webots became commercial it was open source and called Khepera Simulator
Klamp't: a simulator introduced in 2013 specializing in stable trimesh-trimesh contact. Supports legged locomotion and manipulation.
LpzRobots: Another rich simulator with good material support.
miniBloq: This robot programing software for Arduino boards has a new simulator.
MORSE project provides a simulation tools based on the Blender 3D modeling software.
OpenHRP3: (Open Architecture Human-centered Robotics Platform version 3) is an integrated software platform for robot simulations and software developments.
OpenSim Simulator for articulated and wheeled robots with a wide range of characteristics. Further development stopped in the year 2006.
ORCA-Sim: a simulator for robotics: is a (Windows) 3D robot simulator which incorporates the Newton Game Dynamics physics engine. A good alternative for Win32 platforms and the Gazebo project, with fast response and good performance. (Currently not open source. Last update in 2007)
Robotics Toolbox for MATLAB is Free Software that provides functionality for representing pose (homogeneous transformations, Euler and RPY angles, quaternions), arm robots (forward/inverse kinematics, dynamics, simulation, animation) and mobile robots (control, localisation, planning and animation).