Where do our XBee packets go?

An important component of our hardware is a pair of 900MHz XBee radios, one on the robot and the other at our operator control station. We use them as a second communications channel with the robot in addition to the WiFi. Among other messages, the XBee carries the RTK correction data from our base station GPS to the GPS unit on the robot. The XBee configuration also allows simultaneous communication with multiple robots while each robot runs its own contained ROS system. The case of the dropped packets Our issue, discovered while debugging the most recent updates to our XBee interface code, was that some of the packets sent from our operator control station XBee were never received from the robot XBee. We use the XBee in API Mode 1 (no escaped characters), so we can broadcast messages to all XBees within range and target specific XBees as needed. In this mode, the user is responsible for assembling packets with a maximum payload...
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Infrastructure

Half of the summer is gone with little research to show. What I do have is a test track for the robot, a second generation robot under development, and full autonomy tests on the horizon for the current platform. At the end of every week I look at my progress and ask one question: what should I work on next week? What follows is how I try to balance and make sense of the daily logistics requirements, ongoing infrastructure development, and the need for research progress on my current robotics project. How to answer this question is more important than ever to me because I start a new program in the fall. As a PhD student, my job is to solve important unsolved problems in my field to increase human knowledge by some measurable amount. I think these illustrations put it into perspective. Concerning my weekly work, I try to  maximize the likelihood that my robot will do something no other robot has done...
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Using QT in a ROS Catkin Package

This post is a brief account of how to compile a QT GUI as part of a ROS catkin package. I spent the past week migrating a ROS project to the latest release, ROS Groovy. A major change with this release is the deprecation of the build system rosbuild in favor of a new build system, catkin. Catkin is a light-weight wrapper for CMake. Overall, the migration went smoothly, but it took significantly longer than anticipated (which I probably should have anticipated). One sticking point was compiling our Operator Control Station (OCS) GUI, designed in QT4. The problems were related to the removal of QT-specific rosbuild macros for the CMakeLists.txt and the use of out of source builds by catkin. The Setup I used qt_ros to generate a QT form, an accompanying QMainWindow derived class, and a ROS interface class as the basis for the OCS. The original CMakeLists.txt was based on rosbuild and modifications for the transition to catkin. I relied on a variety...
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