A very neat ball-on-a-plate balancing system, featuring mostly low-cost(ish) hardware under 100 EUR. From the description:
Basic control loop with discrete PID and no anti-windup
2% steady state error
2 second settling time
webcam frame rate = 30fps
2 tower pro servos
3 universal joints
1 Ping Pong Ball
(via Matlab MakerZone)
The Expert by Lauris Beinerts
Being an engineer in the corporate world
Percentage of github commit messages containing angry words by language.
when did we replace the word “said” with “was like”
I always thought one uses this form when they does not want to say (or do not remember) what they really have said.
Tweenbots by Kacie Kinzer:
Given their extreme vulnerability, the vastness of city space, the dangers posed by traffic, suspicion of terrorism, and the possibility that no one would be interested in helping a lost little robot, I initially conceived the Tweenbots as disposable creatures which were more likely to struggle and die in the city than to reach their destination. Because I built them with minimal technology, I had no way of tracking the Tweenbot’s progress, and so I set out on the first test with a video camera hidden in my purse. I placed the Tweenbot down on the sidewalk, and walked far enough away that I would not be observed as the Tweenbot––a smiling 10-inch tall cardboard missionary––bumped along towards his inevitable fate.
The results were unexpected. Over the course of the following months, throughout numerous missions, the Tweenbots were successful in rolling from their start point to their far-away destination assisted only by strangers. Every time the robot got caught under a park bench, ground futilely against a curb, or became trapped in a pothole, some passerby would always rescue it and send it toward its goal. Never once was a Tweenbot lost or damaged. Often, people would ignore the instructions to aim the Tweenbot in the “right” direction, if that direction meant sending the robot into a perilous situation. One man turned the robot back in the direction from which it had just come, saying out loud to the Tweenbot, “You can’t go that way, it’s toward the road.”
The Tweenbot’s unexpected presence in the city created an unfolding narrative that spoke not simply to the vastness of city space and to the journey of a human-assisted robot, but also to the power of a simple technological object to create a complex network powered by human intelligence and asynchronous interactions. But of more interest to me, was the fact that this ad-hoc crowdsourcing was driven primarily by human empathy for an anthropomorphized object. The journey the Tweenbots take each time they are released in the city becomes a story of people’s willingness to engage with a creature that mirrors human characteristics of vulnerability, of being lost, and of having intention without the means of achieving its goal alone. As each encounter with a helpful pedestrian takes the robot one step closer to attaining it’s destination, the significance of our random discoveries and individual actions accumulates into a story about a vast space made small by an even smaller robot.
Man this is still one of my favorite little social projects/experiments.
This high-speed video of a bullet fired into a water balloon shows how dramatically drag forces can affect an object. In general, drag is proportional to fluid density times an object’s velocity squared. This means that changes in velocity cause even larger changes in drag force. In this case, though, it’s not the bullet’s velocity that is its undoing. When the bullet penetrates the balloon, it transitions from moving through air to moving through water, which is 1000 times more dense. In an instant, the bullet’s drag increases by three orders of magnitude. The response is immediate: the bullet slows down so quickly that it lacks the energy to pierce the far side of the balloon. This is not the only neat fluid dynamics in the video, though. When the bullet enters the balloon, it drags air in its wake, creating an air-filled cavity in the balloon. The cavity seals near the entry point and quickly breaks up into smaller bubbles. Meanwhile, a unstable jet of water streams out of the balloon through the bullet hole, driven by hydrodynamic pressure and the constriction of the balloon. (Video credit: Keyence)
Acoustic sound is a form of pressure wave propagating through air or another fluid. Place a speaker opposite a plate, and its sound will reflect off the surface. The original pressure wave and its reflection form a standing wave. With intense enough sound waves, the acoustic radiation pressure can be large enough to counter the force of gravity on an object, causing it to levitate. We’ve shown you several examples of acoustic levitation before, including squished and vibrating droplets and applications for container-free mixing. Today’s video, however, shows the first acoustic levitation system capable of manipulating objects in three dimensions, an important step in developing the technology for application. (Video credit: Y. Ochiai et al.; via NatGeo)
Albert grunted. “Do you know what happens to lads who ask too many questions?”– Terry Pratchett, Mort (via dionisea)
Mort thought for a moment.
“No,” he said eventually, “what?”
There was silence.
Then Albert straightened up and said, “Damned if I know. Probably they get answers, and serve ‘em right.