Author: crackingcontraptions_3voi0v

Re: Dewbly batteries

Posted on by crackingcontraptions_3voi0v
Not having to plug in at all would be really impressive.  But it sounds like a helluva stretch goal – on a par with getting it all into a bracelet!

I'm pondering strategy.  I took a helluva long time to get all parts of the hardware working with TS05.  Just getting drivers for the various chips to work took me an embarrassingly long time, and this all has to work before the higher levels of software can be started.  Getting all that goinf for TS05 before I started on the analysis stuff was an error.   I'd like to avoid developing code for all the secondary sensors until we know: 
  1. how many ranging ops we need to do in one day in realistic conditions, 
  2. how much that sucks out the battery,
  3. how repeatable the ranging values we get are.  

For that we need a wearable unit, and some anchors, and the software needs to be getting 

<timestamp><anchor number><range>
records somewhere where we can read them. Almost nothing else matters until that simple pipeline is working and we can see it is going to come in under power budget.  From there on in everything else is just optimization – making Dewbly range more intelligently, report more useful things, and use less power to do it is optional firmware work, and the cloud-based analysis software can proceed independently.
Developing ARM code to get ranges from the DecaWave is going to take me a while.  I've not done drivers for an ARM, and I'm sure there are lots of gotchas.  
But before that even, there's a lot of core (OS) code that has to work before I even get to the ranging stuff. For example I have to get timestamps working, and find a way to initialize the TOD clock with the correct time-of-day for example. 
I'd really like to start with the simplest hand-built OS so the code is small, leaving the possibility of flash space left over to store range data on the ARM itself.  Then I don't have to get the separate flash memory drivers working.
But I do have to figure out how to get the data up to the cloud, or PC.   Maybe it comes over a serial line to start with? I suppose if I have the DecaWave interface working, then I could send all the data over that wireless channel  initially, and if that didn't sink the power budget then hey – we are to first base with the data pipeline, and from there on everything is just 'optimization'.  It's just that the optimization is going to be the bulk of the firmware I expect.
I'm telling you all this because it may have some bearing on your hardware strategy if you know that I'm unlikely to get around to much other than the DW chip for quite a while.  Maybe it buys you some time to figure out some of the more esoteric details of charging, or enclosure?  

//Mik
On Tue, Aug 12, 2014 at 11:50 PM, David Carkeek <dcarkeek@gmail.com> wrote:

It was I who made the mistake in units. 

The Li-Po battery has a lot more usuable energy in it. If we manage energy usage correctly I think we can have a very long battery life. If the solar charging works it may never need to be plugged in.
Which reminds me again that I need to be sure there is a PV cell we will be able to use on the Minitec enclosure.
On Tue, Aug 12, 2014 at 8:31 PM, Mik Lamming <mik@lamming.com> wrote:

Ah.  That showed my complete ignorance didn't it 😀

I always had the model that physical volume was a good estimate of battery capacity, and I was excited to see that my model was violated, but it seems I misunderstood.  Oh well, at least my model is intact.  I wonder when we will get 1000x extractable energy in the same volume.  The harder the challenge the more the triumph.


//Mik

On Tue, Aug 12, 2014 at 11:26 AM, David Carkeek <dcarkeek@gmail.com> wrote:

It's close to the same amount of energy in a CR2032 and fully charged small lithium-polymer pouch battery. I put the CR2032 in W-h but labeled it in mW-h.

CR2032: 0.675 W-h
3mm x 20mm x 30mm: 0.666 W-h
5mm x 30mm x 20mm: 0.888 W-h
4.7mm x 22mm x 29mm: 1.11 W-h

But the advantage of the li-po battery is that large current can be drawn from it without trashing the energy capacity. If button cell is pulsed at high current (high being just a few mA) the energy capacity is much less. I am optimistic that the battery capacity will be adequate.  Making a ring is another matter.

On Tue, Aug 12, 2014 at 9:47 AM, Mik Lamming <mik@lamming.com> wrote:

So a 1000x to 1600x a CR2032.  That a significant difference.  If 1600x lasted one day, then 1000x would be a bit naff.  On the other hand if a 1000x lasted a week, then 1600x is not a significant consideration.

In general, if the difference between one battery and another was the difference between running less-than-a-day and running more-than-a-day then I'd go for more-than-a-day at almost all costs.  If the difference was on a week boundary then I'd go for small.  But since I don't have much clue what our burn rate will be, it's a bit academic.  
At this stage I think I'd maximize your convenience because getting stuff to work ASAP is the priority.  Next we should have a bunch of anchors and a wearable each.  
The first goal is to get daily activity data out of Dewbly onto the screen and into an Excel spreadsheet so we can look at it. It doesn't matter if the devices are big, or small initially.  If we can't recognize patterns in the data, then it will be bloody hard to get software to see them, and we will be done!  
The second goal is to make it easy to gather and upload data every day.  I think the hardware department should take responsibility for making it convenient and reliable for us to gather data day after day, and conveniently recharge with minimal hiccup.   For that reason I think we should try very hard to build two sets of hardware so we can both see the fruits of our labors, and maximize usability – perhaps I mean minimize PITA issues.  
Even if the data presentation software is very primitive, I think it would be very good for you to be able to see what we get.  You'll have different insights and good ideas for how to make things better, or do more interesting things.  I also think it would be good to be able to show early results to potential collaborators if we have any promising results.  Maybe there are retired data analysts, or firmware people who might get excited by good results.
I reckon it will be quite some months before we have anything working well enough to have any insights about battery life.  But firmware work can try and get the burn rate down while hardware can look for ways to get more power into the budget, and recharging schemes.


//Mik

On Tue, Aug 12, 2014 at 7:58 AM, David Carkeek <dcarkeek@gmail.com> wrote:

I have received four of the battery samples I ordered from Ali Express. It looks like a 180mAh battery (3mm x 20mm x 30mm) fits between the PC board posts and leaves enough height for everything else. 3.6V * 0.18Ah = 666 mWh. Recall that a CR2032 button cell is 225 mAH * 3V = 0.675 mWh.

Another larger battery might be made to fit. 4.7mm x 22mm x 29mm, 300mAh * 3.7V = 1110 mWh. One of the posts would have to be cut.
One more sample needs to arrive. It might be the best one if thickness isn't an issue because it will fit between the posts. 240 mAh * 3.7V = 888mWh.

Re: Dewbly batteries

Posted on by crackingcontraptions_3voi0v
Ah.  That showed my complete ignorance didn't it 😀

I always had the model that physical volume was a good estimate of battery capacity, and I was excited to see that my model was violated, but it seems I misunderstood.  Oh well, at least my model is intact.  I wonder when we will get 1000x extractable energy in the same volume.  The harder the challenge the more the triumph.

//Mik
On Tue, Aug 12, 2014 at 11:26 AM, David Carkeek <dcarkeek@gmail.com> wrote:

It's close to the same amount of energy in a CR2032 and fully charged small lithium-polymer pouch battery. I put the CR2032 in W-h but labeled it in mW-h.

CR2032: 0.675 W-h
3mm x 20mm x 30mm: 0.666 W-h
5mm x 30mm x 20mm: 0.888 W-h
4.7mm x 22mm x 29mm: 1.11 W-h

But the advantage of the li-po battery is that large current can be drawn from it without trashing the energy capacity. If button cell is pulsed at high current (high being just a few mA) the energy capacity is much less. I am optimistic that the battery capacity will be adequate.  Making a ring is another matter.

On Tue, Aug 12, 2014 at 9:47 AM, Mik Lamming <mik@lamming.com> wrote:

So a 1000x to 1600x a CR2032.  That a significant difference.  If 1600x lasted one day, then 1000x would be a bit naff.  On the other hand if a 1000x lasted a week, then 1600x is not a significant consideration.

In general, if the difference between one battery and another was the difference between running less-than-a-day and running more-than-a-day then I'd go for more-than-a-day at almost all costs.  If the difference was on a week boundary then I'd go for small.  But since I don't have much clue what our burn rate will be, it's a bit academic.  
At this stage I think I'd maximize your convenience because getting stuff to work ASAP is the priority.  Next we should have a bunch of anchors and a wearable each.  
The first goal is to get daily activity data out of Dewbly onto the screen and into an Excel spreadsheet so we can look at it. It doesn't matter if the devices are big, or small initially.  If we can't recognize patterns in the data, then it will be bloody hard to get software to see them, and we will be done!  
The second goal is to make it easy to gather and upload data every day.  I think the hardware department should take responsibility for making it convenient and reliable for us to gather data day after day, and conveniently recharge with minimal hiccup.   For that reason I think we should try very hard to build two sets of hardware so we can both see the fruits of our labors, and maximize usability – perhaps I mean minimize PITA issues.  
Even if the data presentation software is very primitive, I think it would be very good for you to be able to see what we get.  You'll have different insights and good ideas for how to make things better, or do more interesting things.  I also think it would be good to be able to show early results to potential collaborators if we have any promising results.  Maybe there are retired data analysts, or firmware people who might get excited by good results.
I reckon it will be quite some months before we have anything working well enough to have any insights about battery life.  But firmware work can try and get the burn rate down while hardware can look for ways to get more power into the budget, and recharging schemes.


//Mik

On Tue, Aug 12, 2014 at 7:58 AM, David Carkeek <dcarkeek@gmail.com> wrote:

I have received four of the battery samples I ordered from Ali Express. It looks like a 180mAh battery (3mm x 20mm x 30mm) fits between the PC board posts and leaves enough height for everything else. 3.6V * 0.18Ah = 666 mWh. Recall that a CR2032 button cell is 225 mAH * 3V = 0.675 mWh.

Another larger battery might be made to fit. 4.7mm x 22mm x 29mm, 300mAh * 3.7V = 1110 mWh. One of the posts would have to be cut.
One more sample needs to arrive. It might be the best one if thickness isn't an issue because it will fit between the posts. 240 mAh * 3.7V = 888mWh.

Re: Dewbly batteries

Posted on by crackingcontraptions_3voi0v
So a 1000x to 1600x a CR2032.  That a significant difference.  If 1600x lasted one day, then 1000x would be a bit naff.  On the other hand if a 1000x lasted a week, then 1600x is not a significant consideration.

In general, if the difference between one battery and another was the difference between running less-than-a-day and running more-than-a-day then I'd go for more-than-a-day at almost all costs.  If the difference was on a week boundary then I'd go for small.  But since I don't have much clue what our burn rate will be, it's a bit academic.  
At this stage I think I'd maximize your convenience because getting stuff to work ASAP is the priority.  Next we should have a bunch of anchors and a wearable each.  
The first goal is to get daily activity data out of Dewbly onto the screen and into an Excel spreadsheet so we can look at it. It doesn't matter if the devices are big, or small initially.  If we can't recognize patterns in the data, then it will be bloody hard to get software to see them, and we will be done!  
The second goal is to make it easy to gather and upload data every day.  I think the hardware department should take responsibility for making it convenient and reliable for us to gather data day after day, and conveniently recharge with minimal hiccup.   For that reason I think we should try very hard to build two sets of hardware so we can both see the fruits of our labors, and maximize usability – perhaps I mean minimize PITA issues.  
Even if the data presentation software is very primitive, I think it would be very good for you to be able to see what we get.  You'll have different insights and good ideas for how to make things better, or do more interesting things.  I also think it would be good to be able to show early results to potential collaborators if we have any promising results.  Maybe there are retired data analysts, or firmware people who might get excited by good results.
I reckon it will be quite some months before we have anything working well enough to have any insights about battery life.  But firmware work can try and get the burn rate down while hardware can look for ways to get more power into the budget, and recharging schemes.

//Mik
On Tue, Aug 12, 2014 at 7:58 AM, David Carkeek <dcarkeek@gmail.com> wrote:

I have received four of the battery samples I ordered from Ali Express. It looks like a 180mAh battery (3mm x 20mm x 30mm) fits between the PC board posts and leaves enough height for everything else. 3.6V * 0.18Ah = 666 mWh. Recall that a CR2032 button cell is 225 mAH * 3V = 0.675 mWh.

Another larger battery might be made to fit. 4.7mm x 22mm x 29mm, 300mAh * 3.7V = 1110 mWh. One of the posts would have to be cut.
One more sample needs to arrive. It might be the best one if thickness isn't an issue because it will fit between the posts. 240 mAh * 3.7V = 888mWh.

Fwd: Sensor Fusion, Dempster-Schafer Theory

Posted on by crackingcontraptions_3voi0v
Seems like very useful stuff for me to read.

//Mik
———- Forwarded message ———-
From: David Carkeek <dcarkeek@gmail.com>
Date: Tue, Jul 29, 2014 at 7:23 AM
Subject: Sensor Fusion, Dempster-Schafer Theory
To: Mik Lamming <mik@lamming.com>

You'll probably remember the LinkedIn IoT "Building a Person Tracking Demo" thread that we looked at a few weeks ago. There is a posting from someone mentioning these two things that I don't remember reading about before so just mentioning it in case it might be important.

Fwd: Wearable tech will keep failing — until we can’t live without it

Posted on by crackingcontraptions_3voi0v

//Mik
———- Forwarded message ———-
From: David Carkeek <dcarkeek@gmail.com>
Date: Fri, Jul 11, 2014 at 1:49 PM
Subject: Wearable tech will keep failing — until we can't live without it
To: Mik Lamming <mik@lamming.com>

Wearable tech will keep failing — until we can't live without it

Revealed at the Wearable Technologies Conference in San Francisco: the "dirty little secret" of activity trackers and smartwatches is that they're still not worth it.

large-hero-samsung-galaxy-gear-fit-product.jpgSarah Tew/CNET

SAN FRANCISCO — Raise your hand if you've ever plunked down $100 to $200 on a wearable device, perhaps a Fitbit or a Jawbone wrist-worn activity tracker, and then months later found it deposited in a drawer, without a charge and as despondent-looking as a last-generation cell phone.

Even at the Wearable Technologies Conference held here this week, those who would begrudgingly put their palm in the air included the very same wearables veterans trying to take these devices mainstream. The conference, held annually by the Germany-based Wearable Technologies Group, is a symposium aimed at connecting companies and industry pioneers whose work intersects with wearables.

"I wore a [Nike] FuelBand for the requisite three or four months and then I abandoned it," Kip Fyfe, CEO of wearable company 4iii Innovations, said Wednesday during a talk titled "Wearables don't have to be Wristables."

Fyfe stopped wearing the device because he felt it was inaccurately recording his activity. And for many wearables owners, managing that data and keeping the product charged is more cumbersome than any potential rewards.

The central issue — that these devices are not only expensive and unnecessary, but don't even hold the attention of those who do buy them — is the nascent market's "dirty little secret," Fyfe said. He is not alone in that assessment.

"The No. 1 shipped wearable device in 2013 was the heart rate monitor chest strap. How about that for a technological revolution for you? It has not changed its form factor since 1976," said Liz Dickinson, another industry leader here at the conference who spoke in a talk titled "The Wearable Tech Use Case: What Do Consumers Really Want?"

Dickinson is the founder and CEO of Mio Global, a provider of both standalone heart rate monitors and heart rate reading technology to device makers like Adidas. For her, heart rate monitors are the defining feature of wearables today. "Why on Earth would 12 million people buy these devices last year?" she posited. Nothing else is providing enough value, despite chest-strap heart rate monitors being perhaps the most uncomfortable consumer wearable device you can buy today.

When asked by an attendee what the solution is to increasing the lifespan of wearables, Fyfe's response was no more uplifting than his swift dismissal of the FuelBand.

"You have to find something or some things that people can't live without. The reason people like these devices in our hands," he said, holding up a smartphone, "is because people cannot live without them." Until wearables reach that point and stop being a simplified extension of the smartphone, Fyfe continued, they will continue to be seen as niche devices for gadget lovers and early adopters.

Though the wearable-technology market is estimated to be worth $5.24 billion in 2014, according to market researcher Visiongain, we're all still supposedly waiting for an "iPhone moment," a term that refers to the smartphone boom, which started in 2007 with the introduction of the first iPhone. Such a moment would be a turning point for wearables — when everyday consumers are convinced that they really need to strap computers and sensors to their skin. (Whether Apple's rumored "iWatch" wearable, reportedly in development, will create that shift is unclear.)

However, the smartphone was an evolution of an existing device that many consumers already owned and found to be invaluable. Wearable technology's most popular and recognizable form factors are watches, bracelets, and glasses. Those are devices that not everyone owns, and we have little incentive to ever use or wear computerized versions of them unless several key factors — cost, style, usefulness — reach a perfect balance.

Recent studies conducted by Bank of America and USA Today found that nearly half of all Americans couldn't go a day without their smartphones, and that 3 out of 10 people would go back home if they forgot it. As Fyfe pointed out, nobody is quite willing to say that much for their Fitbit, nor would a day's worth of data lost to a drained or forgotten device impact anyone drastically.

Until then, wearables are trudging uphill.