I worked on fabrication for the Battlebots Season 3 version of Overhaul over spring break of sophomore year. Having never TIG welded before, I was tasked with welding up the mild and AR500 steel weapon assembly for Overhaul. My first attempts resulted in very sad, malformed and misplaced weld beads, but as I found better ergonomics and learned how to control the puddle correctly my welds started to look much better.
With most of the welding complete by the time my spring break ended, the robot went from a pile of parts and a drive base to a mechanically complete robot almost ready to be shipped off to LA in a few short weeks.
I bought my first car on June 12, 2018 :). I had hoped that I would not have to do much to the volvo besides a simple fluids change, but unfortunately I was very very wrong. I realized that I made a life decision that would turn me into a self-made volvo technician far too late. At the very least, I can write about my mechanical mishaps here and perhaps convince you to make the same bad decision.
A week into car ownership, I noticed that my rear wiper stopped working when I tried to turn it on, so I decided to investigate one day after work. I discovered that the wiper would turn on intermittently when my tailgate was open to a certain position, which indicated a failure somewhere in the tailgate wire harness. After removing the pieces of trim that stood in my way, I noticed a few wires with exposed insulation in the area where the harness was attached to the tailgate hinge.
Before I can repair the wire harness however, I accidentally let my tailgate close which severed every wire in the wire harness. At least the wires are all color coded! After grabbing a soldering iron, a battery, inverter, etape and some wire loom, I carefully soldered the wire harness back together. Thinking that it would solve my problems, I went to test my wiper. No dice. After an hour or so of confused multimeter probing and relay fiddling later, I found the root of my problem. It appeared that the act of me playing with the tailgate caused an intermittent short in the wire harness which blew one of the two fuses that controlled the rear wiper motor. It took me a while to figure it out because one fuse was located under the hood, and the other fuse located with the relays in the cargo compartment. In my case, the fuse located in the engine bay was good and I was unaware of the existence of the second fuse in the cargo compartment, which was the fuse that blew.
This is me replacing the autodimming rear view mirror. Unfortunately after all the years and repeated heating and cooling cycles, all the LCD juice leaked and turned the rear view mirror into a black lava lamp. What seemed like a simple enough fix- buying a replacement mirror bolting it in turned out to be far more involved than I had expected. The complexity lies in the fact that Volvo puts the security computer in the rear view mirror housing. After I bought a donor mirror on ebay from a totaled S60, I had to carefully transplant my original mirror computer into the donor mirror housing. If I had chosen to simply replace the entire rear mirror assembly, the donor mirror computer would not be matched to the ECU and the car would effectively brick itself. At that point, the only solution is to tow the car to a dealer and have a dealer level reflash of the computer systems.
Almost immediately after I purchased the Volvo, I realized that my idle was rough and the car would often surge at low speeds. After some internet sleuthing, I learned that it was likely either a clogged PCV or a failing throttle module. Since replacing the PCV system would require taking off the intake manifold to reveal the throttle body anyways, I decided to replace both. The new throttle body I bought was a rebuilt unit made by XeModeX which replaces the contact potentiometers with contactless hall sensors, so it won’t physically wear out over time. Just like the mirror assembly, the throttle module was sourced from a wrecked turbo S60 from eBay. The throttle module gets configured differently between the turbo and non-turbo models, so it was necessary for me to buy a throttle module that came out of a turbo vehicle. This was the most mechanically demanding repair I ever made to my car, and it was my very first time working on a car engine to boot. After a weekend and almost 28 of nonstop wrenching later, the volvo inline 5 roared back to life, this time without the idle hunting and surging.
During my first semester of college, I had to take an intro to engineering class that had a final project due at the end of the semester. The goal was for a group to produce and present a robot that was capable of some interesting motion. It was intentionally very open ended and thus permitted groups to exercise a good degree of creativity in their project designs. I suggested to the group that we could try to develop a 2 wheel self balancing robot- a rather ambitious goal for a project that did not need to be anywhere near that complex. After laser cutting the body of the robot from acrylic, installing the motors and wiring up the arduino to the MPU6050 IMU breakout board, our group settled in for a week of sleep deprived control loop tuning. Tuning the control loop to eliminate ever-increasing oscillations was much more involved than any of us thought it would. To make matters worse, the small DC motor controllers used in the robot died which necessitated a last minute emergency motor controller replacement plan. Without the time to order a new appropriately sized controller, I slapped on my big dual channel 30A Ragebridge DC motor controller to the robot and called it a night.
Then it was back to trying to find the three magic numbers that would allow the robot to self right. After installing bigger wheels and discovering that there was a slight problem was how our integral gain was computed, our group managed to deliver a successful self balancing robot the night or two before the date of presentation.
9S is a 1lb plastic combat robot that I designed and printed 2 days before New York Maker Faire. Since I did not have a lot of small robot parts on hand, the only way for me to create a driving robot in such a short amount of time was to cannibalize the 3lb robot I built earlier in the year and package the parts; motors, wheels and such into a plastic frame that is light enough to pass for a 1lb robot. The motors and gearboxes used in my 3lb robot are way oversized in a 1lb application, so there was not a lot of weight left over for the chassis after considering the weight of the motors and wheels and the lipo battery. A quick trip into soldiworks revealed that the weight of the drive base of my 3lb robot alone was just under 1lb, leaving little in the way of designing passive offensive frame features such as wedges and forks and such.
So I designed some small ramps on the forward face of the chassis and called it a day.
I was pleasantly pleased at how well the 15% infill PLA frame held up. Any crack or hole that developed over the course of the matches could be easily repaired with hot glue. At the end of the day the robot was held together by a NylonX top plate, fiberglass circuit boards and hot glue… it was glorious as it was illegal.
After my negative experiences with cheap low current brushed DC motor controllers, I decided to spin my own. The layout was done in Eagle and the PCB printed with OSHpark. I found a very nice and helpful professor that runs an electronics fabrication lab in one of the engineering buildings who let me come in and assemble my board. My first attempt was not clean at all- the solder paste I used was out of date and I deposited way too much on the board. After fixing the bridges that formed during the reflow oven soldering process, I tried to power on my board and see if it woke up.
But it didn’t. Curiously enough, my voltage regulators also heated up incredibly quickly. After some detective work, I found that the pads for the voltage regulators had reversed the input and output pins. I downloaded the component files for the voltage regulator from a big adafruit library, and did not bother to check if the voltage regulator pin assignments were correct. When I get the time I’ll hand solder the voltage regulator the correct way upside down for the beta testing board. Future revisions will require a new PCB to be printed and ordered.