Feedback and Control

1) Adaptive Optics for telescopes

This is my favorite thing in the entire world! Due to the ever-chaining atmosphere of the earth, observations from ground-based telescopes appear fuzzy, and can only be resolved to about one arcsecond. When observing distant points of light, even the slightest blurriness can result in un-useable data. The newest solution to this problem is to create telescopes with large flexible mirrors that are mounted on a series of pistons controlled by magnets. Essentially, the objective mirror of the telescope is distorted in real time to compensate for the distortion of the atmosphere. In order to know how the atmosphere is behaving, an “artificial star” is created with a laser of known properties shot into the sky. A monitor (the sensing mechanism) reads the brightness and position of the laser, this data is compared to the known location of the laser, and the telescope is distorted accordingly.

This has improved observing data significantly! Here’s an example of just how amazing adaptive optics is. Behold!

2) Automatic windshield wipers

I think this is super cool too! An infrared light source (a frequency that doesn’t interfere with our vision) is pointed at the window, and its refraction is absorbed by a monitor that is programed with an expected absorbance. This is the input, and the monitor is the sensing mechanism. When water is on the windshield, it changes the index of refraction of the glass and scatters the infrared light, reducing the absorbance by a certain amount. This amount is translated into how fast the windshield wipers should wipe, so they move proportional to the amount of rain there is.

This works extremely well, because the driver doesn’t need to activate the windshield wipers manually, and the means of detection don’t affect the driver at all (infrared light). I think that a way this could be improved even more is if it was linked to the car’s headlights as well, because too many people believe that driving in the rain with high beams is a good idea.

3) Elevator

The sensing mechanism of an elevator is the call button at every floor it stops on. The input of the button being pressed is sent though elevator wires, computed and prioritized alongside other inputs from calls on other floors, and then actuated by the mechanisms that move the elevator to each floor and open the doors.

This works well, because the elevator does not need to expend extra energy by stopping at a floor where it isn’t needed; the system is rather efficient. There is one exception to this point that I found innovative and thoughtful. Some elevators are programmed to turn into Shabbat-friendly elevators at relevant times, and the stop at every floor to avoid the necessity of operating machinery. I believe that a better sensing mechanism could improve elevators. Buttons that are pressed by hands will naturally get dirty and accumulate germs, which are less than ideal.

4) Motion-Sensing Escalator

The sensing mechanism is a motion-detector that is triggered when a person approaches. The input of the approaching person is computed and sent to the escalator motor, which actuates the computation and speeds up to a decent speed for an escalator. This saves energy, because the escalators are not always running at their full speed. On the one hand, I believe it would be even more efficient if the escalators stopped running altogether when they weren’t being used, but then it would be difficult to tell by sight whether it was ascending or descending. Of course, this could be fixed with a brightly colored arrow that was simply painted onto the machine.