Posts Tagged ‘ stupid ’

Tricopter: Now in Five Broken Pieces

Curse my impatience.

I got wired control pretty much working, so I went ahead and hooked up my XBees (wireless link) for testing. I had my hand on the chassis just in case, but I guess I didn’t apply enough pressure—it went full throttle on its own (I had barely touched the joystick) and flew off the counter. In two seconds, the tail rotor ripped through my sweatpants and scraped my calf, hit the chair, broke free of its axle and ricocheted into a corner (I spent a good 10 minutes trying to find the detached rotor piece). Somehow, I got three cuts on my left hand, and the acceleration was such that it snapped the chassis into four pieces. Granted, the chassis was made of scrap PCBs, but it was double-layered! All three propellers are shattered and useless.

Anyway, my mother freaked out.

The good news is that I think my motor shafts are okay. My electronics also survived the accident.

I’m probably very lucky that I still have the skin on my fingers and got away with only a few cuts and a welt on my calf. Before I started this chassis build, I cut my thumb pretty badly when I lost my grip on a motor that suddenly accelerated to full speed and landed in my hand (it stopped when it spun itself free of the battery). The jagged edges of the broken rotors would have done much more damage. Why do I never learn from mistakes?

TODO: clean up mess, order new propellers, rebuild chassis, test, test, and TEST CODE.

Raiderbot X Meeting 4, 39 Days to Robot Ship

Meeting time: 15:00 to 21:00

We are two days behind schedule. I started a WOT (Weighted Objectives Table) discussion of the various lift concepts at 3:30. We started with seven concepts:

  • Single-jointed arm
  • Multi-jointed arm
  • Telescope (elevator)
  • Four-bar linkage
  • Eight-bar linkage
  • Scissor
  • 60/40 scissor

We narrowed it down to the four-bar linkage and the elevator and chose the four-bar linkage after a qualitative analysis using a pros/cons list for each. But I still wonder if this was necessary, because it took another 30 minutes of our time and I ran 45 minutes past my proposed deadline of 4:30. Why couldn’t we have reconsidered the two options using the three factors we had rated most highly? Will says some people just need more stake in things? Anyway, my bad for not calling them on it. Areas of improvement:

  • Do not let the loudest voices steer the discussion off-course.
  • Constantly think back to previous discussions and decisions. People were putting the WOT factors under the pros/cons lists, which is nonsense.
  • As always, be consistent, even when calling out for hands when rating the WOT factors. This is no time for jokes.

Will then separated us into four design groups for the lift, claw, base, and minibot.

Four-bar linkage: Mr. Groom found that making the shoulder pivot points’ distance shorter than that of the elbow pivot points allowed the claw to point down when the arm is down and point up when the arm is up. This should allow us to reach both the ground and the top peg as well as everything in between. This makes sense if we think about the four-bar linkage as a trapezoid and shifting the two bases—the linear displacement for the two lever arms is equal but the arm lengths are different, so angular displacements differ.

Minibot: make it as close as possible to a battery with motors glued on.

Preliminary design review planned for Saturday 17:00.

Raiderbot X Meeting 3, 41 Days to Robot Ship

Meeting time: 15:00 to 19:00.

We will have budget discussions every Tuesday after meeting.

FIRST Choice parts ordered, including the FTC Mini Kit for the minibot.

Talked more about end effectors, spent 30 minutes prototyping. Kushal and Damian made a pretty sweet prototype of a four-bar linkage arm.

I messed up here again and completely forgot that we’d planned to finish design decisions by end of the day today. Didn’t happen. Where’s my todo list? I need to make a Gantt chart soon.

Raiderbot X Meeting 2, 42 Days to Robot Ship

Meeting time: 15:00 to 19:00.

Continued talk about end effector design. We built prototypes and tested them in the shop, but just as Will was showing the old triangular scissor lift and I was wondering why there were suddenly so few people, my sister ran in and told me Mr. C (my youth symphony director) was looking for me.

Okay, major slip-up on my part.

Panicked, I promptly ran out of the shop, simultaneously realizing that I had left my violin in my locker and that that was why I felt something was awry as I walked away from my locker earlier today. In the orchestra room, I grabbed and opened a random violin case off the shelves only to discover a long-neglected violin with all four pegs loose and strings going everywhere (and collapsed bridge, needless to say). Fortunately, the next violin was in decent condition, albeit I had to play without a shoulder rest. It wasn’t my first time. It probably won’t be my last.

Halfway through rehearsal, I realized there was a (robotics) team budget meeting at 7:00 I had assured Will I would be at.

I hope never to be so stupid again.