WiTrack

Key takeaways

WiTrack belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect WiTrack to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of WiTrack from memory before moving on to harder problems.

Reference excerpt

A WiTrack is a 3-D motion tracking sensor that is capable of monitoring human body movements. This sensor is able to serve three main purposes, such functions being the following: turning on/off home appliances, tracking a lethal fall, and improving gaming experience. This new piece of technology, currently in its developing stages, was developed primarily by Fadel Adib and Dina Katabi at MIT. The WiTrack functions through the use of radio signals, which help perform the task of finding a person's current location, the radio signals not been affected at all by walls and other physical obstacles present.

Technology WiTrack functions through the use of radio signals that reflect off a person, this does not require a user to hold on to a wireless device like other previous similar inventions. WiTrack uses a total of four antennas, one antenna is used for transmitting signals and three antennas are used for receiving the signals. Through the use of these antennas, a geometric model is created which is able to calculate the distance between the antennas receiving the signals and the user where the signals derive from.

Time-of-flight estimation The time it takes for the signal to travel from the transmitter to the person's body, and back again to the transmitter.

3-D localization Through the use of the antennas, a geometric model is created which is able to calculate the distance between the antennas and the person's body.

Fall detection and pointing WiTrack classifies a fall as a rapid change on the elevation of a person. WiTrack can track the motion of a person's arm and detect on what direction the arm is pointing at.

Future goals The WiTrack was well received, this led to the creation of Emerald. Emerald was an extension to the WiTrack's ability to track falls among the elderly. Just like WiTrack, Emerald tracks the motion of a person through the use of radio signals reflected off the person's body. Once a fall is detected it alerts the person taking care of the elder, or 911. Emerald was presented to President Barack Obama at the White House on August 4, 2015, and was seen as a huge innovation towards tracking falls among the elderly.

Applications

Controlling home appliances A simple gesture, raising your arm and pointing at an appliance, is all it would take in order to transmit a signal. This simple gesture is detected by the use of radio signals, which are then able to turn on/off appliances. This action of turning on and off home appliances doesn't only have to be done in one room, a person is able to control a household appliance even through walls. WiTrack is still able to detect a person's arm gesture even through physical objects.

Identifying dangerous falls among the elderly WiTrack's ability to track motion with such ease and simplicity will make it useful in tracking elderly patients at high risk of falling. WiTrack is able to differentiate a fall from sitting down or standing, it's able to recognize a fall as a fast change in the distance between the person and the ground. WiTrack is able to detect a lethal fall with a high accuracy percentage of 96.9%, making it easy and reliable to use.

Gaming Gamers are able to roam around the comfort of their home, being able to truly interact with the game. WiTracker gives players the ability to run down real hallways, hide behind furniture, and go into different rooms of their home, all while the game is still going.

Similar inventions WiTrack is one of many attempts at 3-D motion tracking technology. This kind of technology has been attempted on both the gaming field and on the field dealing with the tracking of lethal falls among the elderly. Worldwide known gaming consoles, such as the Wii and Xbox Kinect, have long been praised for interacting with their players, involving them in physical activity. These gaming consoles require users to stand at a certain distance and can't stand behind furniture nor behind walls. Current attempts at trying to detect falls amongst the elderly require users to continuously wear sensors or place cameras around their home. These other medical alarms can detect the fall of a person through the use of 3-D motion sensors, similar to the WiTrack.

Issues and improvements A challenge would derive from multipath effects, which create errors in mapping the delay of a reflection to the distance from the target. Sometimes the transmitted signal is reflected from walls and any home appliances. A major issue that is currently being fixed is the measuring time of flight is difficult since RF signals travel very fast. The MIT team is currently trying to fix this issue by using a technique named FMCW, which stands for frequency modulated carrier wave. Another obstacle that stands on the way is the fact that WiTrack is only able to identify one person at a time, but this is being resolved at the time by the MIT team.

References

Worked examples

Example 1 — a first encounter with WiTrack

Start with the simplest possible case. Write down what WiTrack claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to WiTrack before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about WiTrack ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of WiTrack

In research: WiTrack appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses WiTrack in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: WiTrack is common in secondary-school and first-year university syllabi. It links to neighbouring topics Sensors, so understanding it makes those chapters shorter.
In everyday life: Look for WiTrack outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study WiTrack in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what WiTrack means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain WiTrack out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is WiTrack in simple terms?

A WiTrack is a 3-D motion tracking sensor that is capable of monitoring human body movements. This sensor is able to serve three main purposes, such functions being the following: turning on/off home appliances, tracking a lethal fall, and improving gaming experience.

Why does WiTrack matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study WiTrack?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on WiTrack.