The Terrestrial Navigator, or Terregator, is a mobile robot device designed to provide a reliable and rugged testbed for both indoor and outdoor work in robotic navigation, guidance, sensor interpretation, and architectures. The design of mobile robots involves conflicting needs and a wide mix of disciplines. The Terregator design resolves many such needs through flexible and extensible mechanics, electronics, hardware and software. It is a six-wheeled skid-steer machine utilizing compliant tires for suspension, a hybrid power system provides for different modes and environments during operation and a rugged drive system and integral controller provide a complete package for doing robotics research.