New Orleans, Louisiana
June 26, 2016
June 26, 2016
August 28, 2016
Division Experimentation & Lab-Oriented Studies
Undergraduate students in the Experimental Engineering Course at <> College design and fly sensor and signal-conditioning packages on high-powered rockets (total impulse of between 100 Ns and 600 Ns.) The data from these flights are collected using data loggers; this paper will describe the various data loggers used over the history of the course, from commercial rocketry flight computers through our current custom-designed and –built data logger, and the impact on student learning and quality of experimental data.
Although our original plan was to create a custom data logger, a commercial rocketry flight computer was used in early versions of the course; this computer included a 10-bit, 6-channel at 200 SPS per channel data logger with telemetry at 10 SPS. Later a much-lower-cost commercial 10-bit, 8-channel at 200 SPS per channel with a microSD card slot was substituted. Finally, a student performed the detailed design of the custom data logger—the MuddLog16. This data logger has a similar footprint, although not the same pinout, as the commercial data logger. It uses a PIC-32 microcontroller and two Analog Devices 16-bit DACs. The data logger can sample up to 16 channels at a composite 400 kSPS rate. Channels must be selected in pairs, so the maximum sample rate ranges from 25 kSPS per channel for 16 channels up to 200 kSPS per channel for two channels. The data are written onto a 16 GB class 10 microSD card. We have provided LabVIEW VIs or MATLAB m-files for the students to read the data off of the microSD cards. The data logger is configured through a configuration file with options for the number of channels (2 through 16 in pairs) and composite sample rate. The on-board voltage regulators are protected against reverse polarity and will work for any input voltage from 6 V to 18 V (the students usually use a standard 9 V battery.) All 16 inputs are protected against overvoltage and reverse polarity with Schottky diodes.
The MuddLog16 is currently on version 4. Versions 1 and 2 were development versions. Version 3 was the one first mass-produced for student use. The major change for version 4 was the orientation and type of microSD connector. The version 3 connector was a spring-loaded push-push style oriented so the card loaded and unloaded sideways. The push-push style and sideways orientation resulted in cards ejecting during rocket flight and thus not collecting the desired data. The new connector unloads at the top of the board and locks the card in place, ensuring data collection during flight. The data logger interfaces with a custom PC board for the students’ sensor and signal conditioning circuits. The combination was designed to fit in a 54 mm by 12 inch payload section of a commercial model rocket kit such as a PML Phobos or Aerotech Barracuda.
Rubrics were used to assess four years of student work objectives relating to students’ use of data acquisition systems and demonstration of experimental and analytical skills. Students using the MuddLog16 scored higher on the safe and proper use of data acquisition systems, and acquired more experimental data.
Cardenas, M., & Spjut, R. E. (2016, June), Design and Application of High-Speed Data Acquisition Aboard a High-Power Rocket in an Undergraduate Experimental Engineering Course Paper presented at 2016 ASEE Annual Conference & Exposition, New Orleans, Louisiana. 10.18260/p.26657
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