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Month: May, 2015

Never forget where you left your car again, because your phone knows! Also your car is probably worth thousands of dollars, so you should be keeping track of it anyway!

The issue:

When parking on the street or in an enormous shopping center parking lot, it can be easy to lose track of exactly where one’s car is parked.

Since cell phones constantly record a person’s GPS location as a standard feature (if you are not familiar with this, look up “iPhone Track location”—the images are quite striking), we can use this same data to reconstruct the car’s location when it was parked.


Fig 1: Your phone typically does not make this data easily available to you, but it is constantly recording (and saving) your location. This is a low-resolution zoom-out of tracking signals of a phone taken to Las Vegas. Each dot on the map actually represents dozens or hundreds of specific location “pings,” which are just not visible at this zoom level. The black point cluster is Las Vegas itself.


It would be useful if your phone could always tell you where your car was parked—without requiring any user interaction or planning ahead of time.

Luckily, this is possible!

The car location will can be inferred using two sources of data:

  1. By using the accelerometer of the phone (as a pedometer):
    1. When the user is driving, the pedometer should register no (or very, very few) steps.
    2. After parking, the pedometer should suddenly see activity.
  2. By examining the speed of travel between GPS coordinates.
    1. Data points that have an associated speed above 20 miles per hour are practically guaranteed to be in a car (or other form of motorized transportation).
    2. Car data points will still have interruptions (e.g. stop lights) and low-speed sections (e.g., traffic jam) that need to be accounted for.
    3. At some point, the driver will get out of the car and walk to their destination. This can be easily detected by the slower movement and non-zero pedometer data.

See figures 2 and 3 below for an example of integrating these two data types (top of figure = pedometer activity bar graph, bottom of figure = map and GPS “pings”). Try to figure out the parking spot on the diagram below.


Fig 2: Here is some fake sample data. The blue bars along the top (“Number of Steps Detected”) show pedometer / accelerometer activity from 9:02 AM to 9:10 AM (the more a person walks, the higher the bar). The yellow-to-orange-to-red rectangles at the bottom indicate the GPS locations at these specific times. Try to figure out where the user parked the car based on this data. See Fig. 3 for the algorithm’s guess.


Fig 3: Here is the algorithm’s guess for the parking spot—see if you agree with this guess! This is an annotated version of the data in Figure 2.


This feature should definitely be built into your phone!

PROS: Automatically lets you know where you (probably) parked your car, and doesn’t need any data that a modern cell phone isn’t already collecting.

CONS: Might not work very well in underground parking garages. Try to remember where you parked in those situations!

Amazing billiards tip for that will astound your friends and vex your foes. Don’t use it when playing for money, or you may get stabbed!


Relatively few games have equipment choice as an element. For example, in tennis, there is no such thing as a “lob racquet” versus a “serving racquet.”

Presumably this is because of the difficulty in quickly switching out equipment in a time-sensitive sports.

But in a game like golf, where there is plenty of time between shots, golfers carry around a dozen or so clubs for use in various circumstances.

The issue:

This proposal is to apply the same golf-club-selection principle to pool / billiards / snooker.


Fig 1: Billiards in 1674. Apparently played with croquet wickets and tiny pyramids for some reason.

But instead of selecting different cues, players will actually replace the cue ball instead. This will allow for new shot opportunities (Fig 2).


Fig 2: In this case, the player wants to shoot the cue ball between the 8 and the 3 balls, but this is impossible due to insufficient space.


Fig 3: By selecting a tiny squash-ball-sized cue ball, the shot is now possible.

Various sizes of cue ball would be offered, for use in different situations (Fig 4). Selecting the right size for the current board configuration would be just one of the many decisions required for the game.


Fig 4: Various sizes of cue ball would be used by an experienced player. 8 ball shown for scale.


Fig 5: In some scenarios, it might be advantageous to select a huge grapefruit-sized cue ball. It would be difficult to keep this one from rolling off the table, which would also increase the skill ceiling of the game.


Strangely, this “change the cue ball size” rule has never been implemented at any official tournament. Perhaps there were issues in the past with making a perfectly spherical cue ball beyond a certain size. Fortunately, modern technology has solved this problem!

PROS: Adds new and amazing elements to the game, causing a renaissance in billiards techniques.

CONS: It might be difficult to accurately place a different-sized ball on exactly the same spot as the original without some sort of technical aid.

AudioNav: Navigate traffic by audio cues, like a bat. Note: bats are incapable of safely operating automobiles.

The issue:

When driving long distances, maintaining situational awareness on a boring stretch of road can be difficult.

Additionally, distractions such as in-car music may prevent natural audio cues (for example, the sound of nearby cars) from being noticed by the driver.

Proposal for the “AudioNav” car navigation aid:

  1. By using an array of rangefinders along the perimeter of a car, the AudioNav system can determine the location of nearby vehicles.
  2. This information is used to create audio cues, which are then piped through the car’s surround sound stereo system.
    1. For example: a single car directly behind the vehicle would cause AudioNav to generate a constant tone from the rear speaker.
    2. A situation in which there was a car to the back-left and another one to the back-right would cause one tone to come from the rear-left speaker, and one tone to come from the rear-right speaker.
  3. Each audio cue has a pitch component (each detected vehicle is associated with a specific pitch) and a volume (closer vehicles generate louder audio cues).
    1. In other words, the system attempts to associate a particular sound with a particular vehicle, even as that vehicle moves around. This may be difficult.

car_audio_position_1 car_audio_position_2

Fig 1: Rangefinders in the red car locate the nearby yellow truck and blue car. The yellow truck will cause the back-left speaker to generate a tone of one pitch, and the blue car will cause the back-right speaker to generate a tone of a different pitch. As the other vehicles move in relation to the red car, the car computer will make an effort to move each car’s tone in a corresponding fashion between the surround-sound speakers.


Fig 2: Some difficulties might arise in a complicated traffic scenario. In this case, rangefinder A detects car B, and rangefinder C detects car D. Car E is obscured and will not generate an audio tone in the current traffic configuration.


Fig 3: Emergency vehicles (ambulances, fire trucks, etc…) could have their own distinctive tones. Additionally, police vehicles could be pointed out by a unique police-car-only sound. (This assumes that computer vision would be up to the task of identifying an emergency vehicle or police car in the first place.)


This might actually work! It would also provide another reason for a car buyer to purchase the highest-end stereo system, since the extra speakers would be required for the AudioNav system.

PROS: It’s amazing! You should lobby for it to become a mandatory safety feature.

CONS: Probably will be expensive! You’ll have to buy the model without the sunroof in order to afford the AudioNav feature.

The “butterfly” poster design: if you have the misfortune to be carrying a rolled-up conference poster at this exact moment, or are a caterpillar, this idea will resonate with you


Conference posters are frequently 4 by 6 feet, which means that in the best-case scenario, they will still be four feet long when rolled up.

This is still quite cumbersome.

Although relatively few individuals are plagued by the difficulty of handling rolled-up posters, their plight has not gone un-noticed.

The state of the art:

It is theoretically possible to reduce the cumbersome dimensions of a poster in many ways.

  • Wad it up into a ball (renders poster unsuitable for viewing and/or re-use)
  • Fold it into squares, like a map (creases are generally visually unappealing)
  • Fold it into an enormous origami crane

The most common method, of course, is:

Roll the poster up along its longest edge.

But even a 4″ poster is quite annoying to carry around (it definitely won’t fit into any standard luggage) or transport on an airplane. Plus, it is easy to mislay and forget about such a cumbersome and infrequently-carried object.


Fig 1: A typical conference poster is unwieldy and can only be rolled up to a minimum length of around four feet.


Steps toward a new poster design:

One first might consider folding the poster several times along its shorter edge before rolling it up.

This would definitely reduce the poster’s rolled-up dimensions, but testing reveals that the doubled-over sections resist rolling and result in unavoidable crinkles along the long creases when the poster is unrolled (in addition to the unsightly primary creases themselves).


Fig 2: Folding the poster before rolling it, as shown here, would decrease the length of the rolled-up poster, but the doubled-over sheets resist rolling and result in visually unattractive primary creases and secondary crinkling along the primary crease-fault-lines.


But the solution is simple! By simply pre-cutting the poster (along what would have been the vertical creases), we can end up with a “butterfly” poster that is functionally three independent sheets, except for a narrow structural “bridge” element in the middle.

Testing reveals that this poster is quite easy to roll up, and any creasing is limited to the narrow “bridge” elements.

By applying this technique to a 4×6 poster, the final poster can fit into a (potentially oblong) cylinder a few inches in diameter and about 1.3 feet long, which could potentially be carried in standard luggage, or crammed into the side pocket of a laptop bag.


Fig 3: The “butterfly fold” poster is pre-cut along a few crease points.

PROS: Transport is made easier, and poster-losing opportunities are minimized.

CONS: Potential for tearing in the “bridge” region. Also: why not just print three narrower posters in the first place?