Skating Tracker
Alura Sutherland
Project Criteria
Design an accessory that broadens the capability of a smartphone by utilizing external sensors that will wirelessly connect (via Bluetooth or WiFi) to a smartphone and provide added functionality through a “basic” app.
Assigned Sensor - Tracking Device: The device will be paired with the smartphone and provide measurements of an accelerometer, gyroscope and magnetometer—that give it the ability to sense linear acceleration, angular rotation velocity, magnetic field vectors and GPS coordinates. The app should allow to monitor in real time and log motion and position of the device over time.
Additional Criteria
Must house the following components:
Rechargeable Lithium Ion Battery
44.45mm x 34.79mm x 6mm
Printed Circuit Board
40mm x 40mm x 6mm
This product is a wearable training tool for speed skaters. It creates an opportunity to accurately track their performance, including speed, acceleration, and so forth. It pairs with smart phones via Bluetooth, where users can track their results and reflect on their skills and abilities and look for opportunities of improvement.
Research
The research element of this project was a collaborative effort between randomly assigned group members.
ANGULAR ROTATION VELOCITY
● Used to measure the angular velocity an object is spinning at on multiple planes
● Usually made up of multiple sensors, one to measure each independent axis of rotation
● Original analog technology consists of three inter-layed rings that, as the gyroscope spins, react to the angular velocity in they X, Y, and Z direction respectively
● When referring to a gyroscope, the X, Y, and Z movements are also called pitch, yaw and roll
● After measurements are taken, the final vectors are combined to produce a final direction and angular velocity
● A full rotation is required in any one direction to be measured. Any lean or movement of the axis of a wheel does not affect the angular velocity along the spin of the gyroscope due to the law of conservation of angular momentum
● The precision effect prevents gravity from affecting the gyroscope path
● A basic compass is a version of a simple, one-dimensional gyroscope
MAGNETOMETER
● A magnetometer is a tool or instrument that measures the magnetization of an item or the force of a magnet. The magnetometer typically looks at the Earth's magnetic field and local magnetic field in order to determine the location and vector of a magnetic force.
● Magnetometers are devices that measure magnetic fields. A magnetometer is an instrument with a sensor that measures magnetic flux density B (in units of Tesla or As/ m2).
● Since magnetic flux density in air is directly proportional to magnetic field strength, a magnetometer is capable of detecting fluctuations in the Earth's field.
● The Earth's magnetic field is a self sustaining magnetic field that resembles a magnetic dipole with one end near the Earth's geographic North Pole and the other near the earth's geographic South Pole. The strength of this magnetic field varies across the Earth.
LINEAR ACCELERATION
● The linear acceleration sensor provides you with a three-dimensional vector representing acceleration along each device axis, excluding gravity.
● You can use this value to perform gesture detection.
● The value can also serve as input to an inertial navigation system, which uses dead reckoning.
● Conceptually, this sensor provides you with acceleration data according to the following relationship:
linear acceleration = acceleration - acceleration due to gravity
● You typically use this sensor when you want to obtain acceleration data without the influence of gravity. For example, you could use this sensor to see how fast your car is going.
● The linear acceleration sensor always has an offset, which you need to remove. The simplest way to do this is to build a calibration step into your application. During calibration you can ask the user to set the device on a table, and then read the offsets for all three axes. You can then subtract that offset from the acceleration sensor's direct readings to get the actual linear acceleration.
GPS
● GPS means Global Positioning System and it is made up of three parts; satellites, ground stations, and receivers. The receivers are the most relevant to this project.
● Ground control stations play roles of monitoring, controlling and maintaining satellite orbit to make sure that the deviation of the satellites from the orbit as well as GPS timing are within the tolerance level.
● There should be least four GPS satellites ‘visible’ to any place on earth at any given time. Each one of these satellites regularly transmits information with regards to their position and the current time.
● GPS receiver interpret the transmitted signals, which then use the travel time to calculate the distance they are from the corresponding satellite.
● If you know the distance you are from four individual satellites, a sphere with that radius is projected. The spot where the four spheres intersect is your exact location at that time. This process is called Trialation. The more satellites there are, the more accurate your coordinates are.
● GPS satellites are equipped with atomic clocks to keep accurate time. However, General and Special Relativity must be considered when comparing these clocks to an identical clock on Earth. General Relativity suggests that time will appear to run slower under stronger gravitational pull, meaning that time seems to pass faster in space. On the other hand, Special Relativity predicts that because the satellites’ clocks are moving relative to a clock on Earth, they will appear to run slower.
Process
The App
This app connects via blue tooth to the tracking device. Through the app, athletes are able to track their performance during training so that they are able to reflect on their experiences and see where they can make improvements.
The functions of the app include recording and analyzing races, as well as viewing additional resources such as training videos.
The aesthetic of the app is to reflect the design of the tracking device to create a sense of unity between the different elements of this product.
A parent/coach can record the athlete during their skate. This way they can analyze their form with relation to their stats (time, velocity, acceleration, and the angle in which their blade touches meets the ice).
The recorded runs can be saved in chronological order so that athletes can see trends and reflect on the progress they have made over time.
This product is made for training purposes only. However, through this function, skaters have the option to manually record their scores from tournaments to keep track of their performances during the season.
The settings menu allows for functions such as connecting to the the tracking device, changing the unit of measure, and selecting whether the athlete is training long track or short track.
Final Design
Use Cycle
Steps 1 through 6 are performed by the skater.
A coach or parent use a phone/app to video the skater (step 7).
The wearable device wraps around the athlete's leg. The sensor should rest on the inner side of the leg to avoid impact during wipe outs.
The strap that secures the sensor to the athlete is made out of silicone; withstands extreme temperatures, is flexible in nature, and is impact resistant.
The athlete can power and pair the device manually. The recording of the race can either be done manually from the device or through a smart phone via the associated app.
The buttons are concave, as to not be accidentally pressed during use.
The buttons are placed in order of operation; power, check battery life, pair device, record race, stop recording.
The battery icon has bars that illuminate in relation to the battery life left. The battery life is also indicated in the app.
The sensor is long and flat to be as streamline as possible. Minimizing the affects that it has on performance.
