# Computing stuff tied to the physical world

## Who needs numbers?

In Software on Jan 19, 2013 at 00:01

I’ve always been intrigued by those “control panels” with lots and lots of numbers on them. It seems so much like old science-fiction movies with unmarked buttons all over the place.

That and the terror of the linear scale felt like a good reason to try out something new:

Ok, so here’s the idea:

• you’re looking at four copies of the display next to each other, with different readings
• the vertical scale is power production (top half) and power consumption (bottom half)
• green is production (+), red is consumption (-), and blue is the difference (+ or -)
• it’s logarithmic, top and bottom are 5000 W produced and consumed, respectively
• the green and red dots are also log-proportional, the blue circe has a fixed diameter
• the center has a ± 50 W dead zone, i.e. everything in that range is collapsed to a line

Now the examples, from left to right:

1. end of the afternoon, no solar power, about 260 W consumption
2. induction cooking, consuming about 2500 W
3. night-time, house consumption is 80 W
4. daytime, 1500 W production, 200 W consumption

Those last two readouts were simulated since I didn’t want to wait for a sunny winter day :)

The data is shown LIVE, and I’m going to keep it around to see whether this is an intuitive way of presenting this sort of information. It’s all implemented using the HTML5 canvas.

PS – I’ve since switched to “sqrt” i.s.o. of “log” for scaling. Looks nicer with large values.

1. Neat! Surprisingly little canvas code too. But why the need for scales? Blue circle is max capacity of your utility connection, for reference. Red circle is consumption, green circle is production. Largest circle goes in the back. SQRT scaling is inherent to area of circle(s), but log scaling could be used as well. With a single color LED this is also relatively simple to implement. Light intensity of the colours indicate production (green channel) or consumption (red channel). No light is OK, bright green is best, anything from orange to red means overconsumption. If the LED faces the wall, I would be surprised if the radius of the shine would not somehow correspond to the amount of energy that is flowing :-) How’s that for a simple display?

2. Scales? Eh, just to get that Start Trek look? ;)

Yeah. lots of display potential… thx for the suggestions!

3. Ingenious, but please also design for the ~12% of caucasian males that are red/green colour deficient. While it may seem blindingly clear to you, it is a muddy blur to us ;-)

Yellow/Blue is more universal and red should be reserved for alarm/fault conditions (though increasing energy bills are perhaps alarming enough)

Interestingly, there is a showdown coming between Big Power and small scale renewables in the USA. They adopted the simple system of ‘turn the meter backwards’ for excess local generation, largely on the grounds that it is an easy concept to grasp (and supercheap to implement since many clunky installed mechanical meters had no reverse blocking anyway). This is equivalent to buying back power at the full retail rate. Fair enough? No sir, we are forgoing that fat margin between the wholesale purchase price and the retail price. We need that to pay for the long distance distribution (not, physics tells us that what is excess is consumed locally), new BIG power plants (not – renewables can fill the growth gap) and to pay for rolling out Smart Metering (hmmm – dubious).

If you grant a monopoly, don’t expect the monopolist to work in your best interest…

• Ah… but I did!

The green circle never drops below zero and the red one never rises above it. The blue circle is the only one which can be anywhere, and it has a distinctive shape.