Friday, March 25, 2011

Deployment Plan

Our medium fidelity prototype is in short, a flower pot with power sockets on the front. Consuming power from the pot will cause a light in the flower to grow dimmer, and the flower will begin to sag. Using more power will cause the light to grow dimmer still, and the flower to sag faster. The light provides an immediate feedback of your power use, while the flower "wilt" provides a view of this usage over time.

The prototype is intended to be used as a desktop or counter-top power bar. In addition, we view it as a decorative device that people may want in an area of visibility or low light. However, using the pot as a power bar will "kill" the flower sitting on it - this discourages the use of power. Our thought is that this ambiguous context may cause people to think twice about the power they consume.

Our prototype is meant to be artistic in its message and form, but also very utilitarian. It can be used as a simple power bar, or as a decorative piece, or both. It also piqued our interest as a programming challenge - how can we get the Arduino board to sense power usage? We believe we have met all three challenges admirably.

Our flower will be deployed in the home of a family of three: a mother, father and and son. The son in the family is a fellow SIAT student who is known to John. The mother is a housewife, who is very power-conscientious. The father is a retired individual, who may spend long hours at home.

Due to the presence of the mother, the family is well known for its efforts at consuming power. The household will often turn off lights that aren't in use, or devices that aren't very effective. We feel that our device suits these ideals admirably, and may prove useful in their lifestyle. We feel in will likely be deployed in a work area, such as the computer desk - though other avenues have been considered, such as a kitchen or bathroom.

We plan to introduce the flower as a decorative power bar which will react to how you use it. We will assure the family that their are no external sensors on the flower pot, and it will not keep any records of what it does. Attention will not be drawn to the exact behavior of the flower, or what stimuli it will react to. Our hope is that the family will realize this for themselves.

The prototype will be deployed Monday through Friday, with a Wednesday recording session placed in the middle. John lives within walking distance of the family, and can thus visit them as needed to give reminders and see how they are doing.

Sample questions include:
1) How often do you use extension bars?
2) What do you use them for?
3) Was our prototype useful?
4) How did it react to you?
5) Did you change your behavior while around our prototype?

When our results are retrieved we plan to use a Affinity Diagramming to find patterns. Once categories are established we will look for additional collaborating information, and use it in composing our report.

Medium Fidelity Prototype

As previously stated, Flower Power is a smart appliance designed to draw attention to power consumption through the symbol of a flower. The installation is a flower pot with multiple plugs on the front. These plugs encourage power use, suiting the flower to an office space - where it can act as decoration and utility. However, this behaviour will be directly punished. The flower is lit by an LED light, which indicates your current power consumption. Adding more devices to the light reduces the luminosity, indicating the flower is drawing less life from the power line. If power usage continues, the flower will begin to wilt - the rate determined by the dimness of the LED. The rate of the wilting will be slow - about 1 - 5 degrees per minute. The intent is that it is hard to completely kill the flower, and just as hard to restore it. The flower will recover at a lower rate.

The device makes use of ambiguous context, by pitting two objectives against each other - utility and the fate of the flower. While the user may want to use more and more devices, the flower will show them its effects on the environment, discouraging this use. It also makes use of ambiguous information - giving no concrete power values that the user can use for comparison. It is our hope that by abstracting the numbers into a visual indicator they will become more aware of the scope of their power use.

In this prototype we have completely redesigned the flower wilt mechanism. In previous iterations we cited muscle wire and string pulleys as mechanisms. However these proved to be impractical or impossible, based off of the technical knowledge of the group and our shopping prowess. We have therefore changed the mechanism to a rotational one involving a servo motor. This idea will be explored in detail below, when we go over how the design works.

We also reworked our pot - incorporating a rock bed where the stem meets it. This bed of stones disguises the opening, making the flower feel more "alive". The stones were chosen for their low frictional value, so they would not hinder the servo.

The design is intended to be used as a table or desktop power bar. People plug in their devices and use them at will. The flower itself will discourage use, putting itself at odds with the utilitarian design.

Care was taken with the exterior and interior of the prototype due to several reasons. Our care on the inside was due to the very real danger of electrical fires. To mitigate this, we have lined the pot with fireproof & shockproof electrical tape, and securely soldered each join in place. We then covered each join individually in the same tape. On the outside, care was taken because of the nature of the device. If it looks poorly constructed it was unlikely that users would be willing to plug their devices into it.

Without further ado, let us introduce you to the prototype:

Six plugs line the front of the pot, with the flower placed at the top.

A 6 foot extension cord runs out the back and plugs into the wall.

The power for these plugs (and our internal power line) is provided by the "trunk" circuit shown below.

The wall power is our 6 foot cord. Upon entering the pot it branches two ways. One goes to a DC power supply which keeps our Arduino board running. The other line continues on, with the hot wire passing through a current transformer used in the current sensing circuit. The circuit then forks, with one half going to an AC step-down transformer (used to detect voltage), and the other to the sockets which the user will plug devices into. This design has been implemented as seen below.

Once the trunk was established, we began sensing current and voltage. These will be covered separately for simplicity's sake.

First the current sensor:

From the 5V connector of the Arduino we have 2 resistors and a capacitor. This configuration has the net effect of adding +2.5V to the voltage sensed by the CT. This prevents the power from flowing out of the Arduino Analog In pin, causing the board to be damaged. The CT is paired with a 170 ohm "burden" resistor. The resistor prevents surges from the ct sensor (caused when devices are turned off) and helps to translate the current sensed by the CT into a voltage that the Arduino can read. The burden resistor has been specifically selected for our CT by us, so as to provide the maximum power range to the board with the minimum risk of surges.

The voltage circuit can be seen below:

This circuit has a similar setup on the 5V pin, and it provides the same function - it adds 2.5V to the power given by the AC transformer. The other two resistors step down the voltage from an alarming 7V (from the Arduino board's point of view) to a more respectable range of about 4-5 volts.

These two circuits are added to the pot below.

The Arduino board then calculates the power, and uses it to divide the usage in to 6 "tiers". The LED brightness and flower tilt are then adjusted based off of what tier you are in, and if you remain there. The circuit for this is seen below.

The flower is made of a floppy plastic tube covered in green tape. The tube has a certain sag to it - giving a natural feel. To "wilt" the flower, we rotate a disk the tube is attached to inside the pot, making the tube lean forward. The tube sags in that direction, making the feeling more natural.

In practice, the motor and LED light wires look like this:

Friday, March 11, 2011

Low Level Revisions

Since the last report on our flower prototype, several issues have come to light. These issues have prompted a review of our design, leading to changes (in some cases) or clarifications (in others).

We have chosen a flower to represent power consumption because of the ideals it represents. Flowers are delicate and easily damaged - it is therefore more believable that a flower would wilt from power drain than a small tree. Animals were also discarded, as such shapes encourage play with the object and may lead to it being broken. The flower itself was chosen because it is commonly linked with nature and green ideals. We wished to make users see how they are killing those ideals by wasting power.

Looking over the flower's behavior we have to agree with Carman's comment - both the LED and the droop feature are performing the same function. We thus sought to find a use for both (or failing that discard one in favor of the other). In the end we realized there was no indicator of your current power use. You can see that you have used too much power over the last hour, but not if you are draining the flower now. We have thus changed the function of the LED light to show users their current power drain. The more power the user is consuming at the moment, the dimmer the LED will grow. The LED's dimness will be divided into 6 tiers of power consumption - the higher the tier, the quicker the flower will wilt over time. The use of 6 tiers allows users to see immediate feedback if they reduce their power use, while still preserving the use over time intent of our design.

During this week we have recieved all the power sensors needed to detect power consumption. Upon reviewing these devices we quickly realized that our plug would be far too large. In response to this we have changed the design of the flower pot as follows:

Now all electrical components are inside the flower pot, and the power expansions are a part of the pot itself. This effectively makes the power drain metaphor more direct, while solving our sizing issues. The two cables running to the right will go to a simple plug that will go into the wall.

This change in design means that our device will likely be used in a desk environment, such as a computer workstation. Knowing this will allow us to set the power drain rates for our flower more easily

Saturday, March 5, 2011

Refined Plug Diagram

The tidy up effort on the plug diagram has just finished. This diagram may help in puzzling out the circuitry inside our plug. The circuit is identical to the one illustrated below.

Friday, March 4, 2011

Low Level Prototype

Out of our two concepts last week, we have chosen to proceed with Flower Power. This design was intended to increase interest in power-saving, by making the side effects readily apparent. As more power is consumed, a flower in a pot near the plug begins to wilt, while an LED placed in its centre loses its brightness. If the participant reduces their power consumption, the flower will recover, encouraging minimal power usage. Regardless of the outcome, the user will become aware of how much power they use, making them think about it a little bit more.

The design process for this prototype was fairly straightforward. We met on Tuesday this week and went over our concept, breaking it up into smaller problems that needed solving. We then assigned each problem to one group member, who began researching it overnight. By Wednesday all research showed that the designs were feasible, and arrangements were made to get supplies. Friday was dedicated to detailed analysis of our prototype, including the creation of full wiring diagrams and the creation of a computer generated prototype.

Our current plan for the project is one of iterative development. The team gets together and to figure out what we want to do, and how to go about it. After the meeting, tasks will be assigned to each teammate, who will bring their work to our 3rd meeting. At that time, we will try to assemble all developed resources together, and observe the results. Any failures will be noted, and brought to the next meeting, where we begin the next cycle.

At present our prototype takes the form of two components: A plug and a flower pot.

The plug takes the form of a power socket expansion, offering (at present) 6 electrical outlets for the participant to plug their devices into. It also has several bundled wires running from it to the pot.

Inside the expansion are 3 electrical devices: a DC power supply, an AC down-converter, and a Current Transformer Sensor (CT Sensor).

The DC power supply provides power to the Arduino board in the pot, and takes up one of the two wall sockets. The power supply will convert power through the use of magnetic fields, making it hard for current to flow back through the outlet and shorting out the Arduino board.

The AC down-converter will be used to convert the 120V wall power to a more manageable 9V, allowing us to detect the voltage of the line without frying the Arduino board. It too connects to the pot.

The CT Sensor will allow us to measure the current in the line. It too sends wires to the pot.

The pot on the other hand houses the Arduino board and all of our analysis circuitry. A diagram is visible below.

The CT Sensor and AC down-converter connect to the Arduino board through a complicated circuit, designed to remove the AC nature of the power, and allow us to detect both current and voltage. These values are read by the Arduino board, which then uses them to find the power consumed. Using additional pins, the board responds by changing the position of the flower and the brightness of the LED.

Our current method for controlling the flower’s angle involves the use of flexible plastic piping and a piece of thread. This thread is attached to a motor or servo, which will pull the flower down into a curve. Analysis of both methods had begun, but was not finished by the time this report was submitted.

Most of this information is irrelevant to the end user though, who we expect will use the plug as you would any power bar. The use of an expansion in the plug base encourages heavy power usage, while the flower could be placed nearby to act as decoration. By moving the flower off the plug, we hope to make it less likely that participants will hide the flower by putting the plug under a desk.