In order to construct Intel Labs Seattle’s mobile robotics platform, MARVIN, I needed to build a power system to supply the DC voltages required by the different components of the system. I used nickel-metal hydride battery packs as the battery power source and VICOR DC-DC converters to provide the various required voltages. The control panel on the rear of the robot is laser-cut acrylic and provides control over battery power, battery chargers, power to individual system components, and battery current and voltage monitoring.

One of the important features of the design is an onboard AC to DC power supply. This allows the robot to run indefinitely from a single tether, which plugs into a standard electrical outlet; no external power supply is needed. The system switches seamlessly between wall and battery power when wall power is connected or disconnected, so no part of the system needs to be shut down to connect or disconnect power. Onboard chargers enable the robot to recharge its batteries while it is plugged in.

picture of the back of a mobile robot showing power meters and switches
MARVIN's rear control panel. The power module controls are at the bottom.

UW Classroom Presenter, developed by Richard Anderson et al. at the University of Washington, is interactive presentation software that runs on tablet PCs. Each student uses his or her own tablet PC, can see written annotations made on the slide by the instructor (called “ink”) and can add his or her own ink to slides which can be submitted back to the instructor to be reviewed or shared with the class. In my undergraduate capstone project at the University of Washington, I worked with several other students to develop a version of Classroom Presenter that runs on the One Laptop Per Child foundation’s XO laptop.

The software is not just a port but a complete adaptation to make it usable on the XO. The XO is not a tablet, so only simple drawing with the trackpad (or a mouse) is possible. We added text input features to enable students to provide a textual response to a question without needing to write it with a mouse. We use the XO’s built-in facilities for discovering shared activities and connecting to other machines, so that connecting the machines together is simple enough for elementary students to do themselves. We also included features necessary for setups that don’t include a projector: the original UW Classroom Presenter expects that if the teacher wants to share a student’s submission with the class, he or she will use a projector to display it. In our implementation, we enable the teacher to broadcast selected student submissions to the rest of the class, so students may view them on their own screens.

The project culminated in a trial at a local elementary school, where students in small groups shared XO laptops to complete activities about a recent field trip, while the teacher talked about the students’ work and shared their submissions with the rest of the class.

This board that I developed fits inside of each of the three fingers of Intel Labs Seattle’s mobile robot. It includes two resonant transmitters for generating high voltage AC signals, two analog front-ends for amplifying the received current to be fed into the microcontroller’s ADC, and enough processing in the microcontroller to perform synchronous demodulation on the received signal.

E-field sensor board for robot fingers
E-field sensor board for robot fingers

Each transmit-receive pair has unique geometry and constitutes a unique measurement. Within a single finger, four different transmit/receive channel pairs are possible: with the current antenna configuration in the fingers, there are split left and right receive electrodes and mid- and short-range transmit electrodes. Each finger can also be linked to a third transmit electrode in the palm of the hand, which provides additional left and right long-range channels.

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