Sensors and Electronics

Kratos has three sensors for pose (position and orientation) measurement a Hemisphere GPS unit provides latitude and longitude measurements accurate up to 10 cm. A Honeywell digital compass provides measurements of heading. Optical encoders are mounted on each wheel axle to measure differential wheel speeds for dead reckoning. A single Point Grey Research Bumblebee2 color stereo camera serves as Kratos’ only environmental sensor, allowing the robot to “see” obstacles in its path and lanes painted on the ground. All digital I/O is handled by a LabJack UE9 data acquisition unit, which takes inputs from the encoders and outputs PWM signals to the motor controllers. The robot’s remote E-stop is handled by a R/C radio receiver attached to an Innovation First controller unit operated on a separate power supply from the rest of the robot.

Power Systems and Computing

The three 12VDC deep-cycle batteries onboard Kratos provide enough power for up to one hour of full operation and over 5 hours on standby. A battery charger is also mounted onboard, allowing the robot to charge by simply plugging in to a standard socket. Two custom-built Intel Core2Duo-powered computers handle the navigation algorithms and stereo vision computations, respectively. As with all other PAVE robotics projects, Kratos’ computers are connected to a pair of wireless routers configured to allow access to the internet and to allow developers to connect remotely.

Software

Both computers on Kratos run Windows Server 2003. All software development was done in Microsoft Visual Studio. This combination allowed us to work with a set-up we were familiar with from our participation in the 2007 DARPA Urban Challenge. However, we did use a different software framework, the Interprocess Communication Framework (IPC). We developed a C++ wrapper for IPC, dubbed “IPC++” Learn more about IPC++ and other software and hardware technologies used on Kratos and other PAVE projects in the technologies section of our website.

Achievements of the 2008 IGVC team

At the 2008 IGVC, Kratos finished 4th place in the Navigation Challenge (waypoint following and obstacle avoidance), finished 6th place in the Autonomous Challenge (lane following and obstacle avoidance), and completed the JAUS Challenge (interoperability with a robotic communication standard). In addition, the team earned 1st place honors in the Design Competition for our Tech Paper (PDF) and design presentation.

Overall, PAVE finished in 3rd place out of 47 teams at the 2008 IGVC, and was also awarded Rookie of the Year.

Summary videos from the competition are available:
Day 5, Day 4, Day 3, Day 2, Day 1

View additional pictures of our team at the 2008 IGVC at the IGVC website.