My first lesson was to build a universal F2808 DSP board that the lab uses for microcontroller applications. This small and relatively simple board has all the challenges of proper soldering. Aligning the 2808 chip took 3 or 4 tries, as the slightest misalignment could make very small solder shorts. While the SMD resistors are labeled with a tiny code, the capacitors are differentiable only by size and color. The same size and color chip can be 2 or 3 orders of magnitude difference; if the wrong one is soldered on, it's almost impossible to diagnose afterwards.
The A/D board I built next functioned properly, though this time I had to contend with power components. The large copper area connecting to the DC/DC converter dissipated heat, making it tough to get a clean contact.
Next up was soldering the motor controller board. Lacking PSPICE, I designed a simple Excel sheet to account for all the components off of the schematic. I wrote a few formulas to convert component values to part numbers, which could then be sorted.
Soldering all of one component at a time ensured that I missed none, and that only one kind of identical-looking part would be on the table at a time. For the amplifier, a neat little trick to get the MOSFETs to line up properly was to bolt them all to the heatsink first.Other accomplishments:
- Obtained copy of HUBO dynamic walking PhD thesis by Dr. Jung-Yup Kim
- wrote a brief MATLAB simulation of a lab project: the pneumatic pogo-stick
- Photo tour of important buildings in KAIST
- Took a photographic sequence showing major steps of leg and arm assembly
- Rebuilt 2 broken harmonic drives; learned assembly/repair technique for similar drives located throughout the chassis.
- Assembled a DSP board and IMU A/D board from scratch
- Assembled a complete motor controller set (controller and amplifier)
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