CARMEN is modular, Open Source C software designed to provide basic navigation primatives including: base and sensor control, obstacle avoidance, localization, path planning, people-tracking, and mapping. Licensed under the GNU GPL. http://www-2.cs.cmu.edu/~carmen/
A library, environment, graphical user interface, and low-level drivers to explore AI and robotics using the Python language. Pyro is Free Software licensed under the GNU GPL. http://pyrorobotics.org/
A complete Unmanned Aerial Vehicle (UAV) control system with 3 axis IMU/INS+GPS. Autopilot is Free Software and, along with the associated hardware designs, is licensed under the GNU GPL. http://autopilot.sourceforge.net/
ARIA is an OO C++ library for controlling ActivMedia mobile robots. Provides dynamic control of velocity, heading, and other navigation settings as well as I/O bus, gripper, pan-tilt, and bumpers. ARIA is Free Software licensed under the GNU GPL. http://www.activrobots.com/SOFTWARE/aria.html
MARIE is a development and integration environment built over a communication layer. Its main goal is to integrate other robotics software such as Player/Stage, CARMEN, and RobotFlow. MARIE is Free Software licensed under the GNU GPL. http://marie.sourceforge.net/
PID-based odometry and dead-reckoning for a mobile robot with differential steering, implemented for a Lego RCX module. Detailed article describes theory of operation. Open Source software written in the NQC language and released under an MIT license. http://www.seattlerobotics.org/encoder/200108/using_a_pid.html
VSA provides MS Windows-based motion control compatible with servo controllers commonly used in robotics applications such the Mini SSC, SV203, and SMI boards. VSA is proprietary, commercial software. http://www.brookshiresoftware.com/
A software platform and associated hardware with a focus on educational use. Software can handle 100+ I/O ports, up to 12-16 servos and many DC motors. EGgO is written in Python, runs on Linux and is Free Software licensed under the GNU GPL. http://eggo.sourceforge.net/
Official production releases and source code from the now defunct Nomadic Technologies, Inc. Source code to all drivers, libraries and applications is now under the GNU GPL license. http://nomadic.sourceforge.net/