On Thu, 22 Oct 2015 21:03:08 -0700, Jeff Liebermann Gave us:
The 'feature' of this release is the low latency kernel it uses, and that makes it perfect for installing kodi onto it.
This is also a low utilization desktop, and is good for lab related stuff.
On Thu, 22 Oct 2015 21:08:53 -0700, Jeff Liebermann Gave us:
Do not use the AC driven controller unit. The motor itself is not an AC device IIRC.
On Thu, 22 Oct 2015 21:08:53 -0700, Jeff Liebermann Gave us:
It is not a chain drive. It is a linear actuator in which the door opener arm crawls across a taut chain mounted in a rigid formed rail. Perfect for the tracker, in fact. You know... needs matching and all that.
See:
(note north/south reversed as he lives in southern hemisphere)
I'm going to mention it this time because it hasn't been mentioned yet.
thermal hydraulic.
basically two bottles of volatile fluid mounted behind the panel and normally shaded by it, when the sun shines it if it shines on the bottle it boils the fluid which then works one end double-acting piston-cylinder which re-aims the panel until the bottle is sufficientl shaded.
-- \_(?)_
With +/-5 degree accuracy, tilt the panel to +18 degrees on April
22th, tilt to +8 degrees at Aug 19th, tilt to -2 degrees on Oct 12th and so on. Not that many times tilt adjustment required.There is also an error due to the Equation of Time causing +/-20 min differences when the Sun is in South. This there is an additional +/-
5 degree error in that direction.It should be noted that at 5 degree error, the illumination drops to
99.6 % and at 10 degree error the illumination drops to 98.4 %, so no big deal.Of course, if you are using mirrors and lenses to concentrate the sunlight, the error is a problem.
Sure, connect it to the main solar array with a mechanism similar to power steering. It only has to move the valves/switches, not the entire panel.
Except that it is far from optimal. I would only be in the correct position at one point in a day for any day other than two out of the year. Towards the start/end of the day the angle would be very far off much of the year.
-- Rick
Hi, Erica -
It would be helpful to know if this is an academic project or a practical project. In other words, is this a challenge to see what it takes to do the tracking or will it be applied somewhere?
If it is just an engineering challenge, you already have great advice in this thread. If it is a practical problem, have you done a systems calculation to determine the necessity of tracking?
For example, the summer months have longer hours of daylight. Do you really need to track? The list of considerations for making an engineering decision can be enlightening.
Cheers.
do
programmed
Sun.
required.
You don't need to track it, its path is predictable.
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On Fri, 23 Oct 2015 08:01:01 -0500, "cbarn24050" Gave us:
It pretty much stays where it is (relatively). It is our path we are tracking actually. (untracking?)
I did a 2D version of that at IBM that had an interesting wrinkle. It was for a 500-2500-sun concentrator, so it had to be dead nuts.
This one used the fluid bottle idea for the coarse tracking, to bring the image of the sun onto the cold plate (if not necessarily onto the detector). Once it was there, it kept the sun on centre by zeroing out the temperature gradient on the cold plate using three or four glorified coffee percolators fighting each other. IOW working fluid boiled in tubes attached to the cold plate, which pushed liquid into reservoirs near the edge. They were placed so that if one side got hot (so that it pumped faster) it moved the solar image away from that side and towards the middle.
The loop gain was roughly 100 times higher in the fine tracking mode, which meant that it would stay on target very well. Gravity siphoning made it swing back to the east once the sun went down. Fine lock acquisition should have worked OK since when the image hits the cold plate, it moves the right way from the start, even though it's on the opposite side of the position of maximum pumping rate.
The other novel feature was that the whole thing lived in a plastic sphere full of water, which looked after the cooling, focusing, and weather protection. (It needed a small segmented mirror as well, to compensate for the gross spherical aberration. Since we only cared about on-axis performance, this worked fine.)
I had the coarse tracker working when the project got cancelled, but the fast tracker simulated very well.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Canonical, eeeewwwww.... How about a nice Debian or Mint?
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
How about motors from Electric Power Steering? They run from 12V DC.
On a sunny day (Wed, 21 Oct 2015 17:02:29 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :
These days just use a camera and a few lines of asm to track and / or find a light source:
1D
I'd try something with 3 LDR resistors in 22.5 degrees, and simply move towards the highest signal.
I would remember "yesterdays first position" and go that when it gets really dark". From there the sun will drive it.
This is an idea, which will need some development, but hey - that is the fun.
LDRs are horrible. Not only are they slow, but they have terrible hysteresis--their resistance can vary by a factor of 5 due to previous illumination history. Photodiodes are cheaper and better, and of course you don't need much photodiode area to see sunlight.
Three photodiodes behind an equilateral-triangle shadow mask is the ticket. Arrange them so that they're halfway covered when the source is on axis.
Taking the appropriate sums and differences will give you X and Y independently.
I did that for a computer input device about 20 years ago--it was a noncontact head tracker that shone AC-driven IR LEDs on your forehead and watched the blob move around in space using three lock-in detectors made from three MC1496es and a CD4052 dual 4->1 MUX wired up as a three-input flying capacitor subtracter.
For a real 2-axis tracker, you might as well measure what you care about--power output--and use a bit of dither in each axis to find the peak.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
On a sunny day (Fri, 23 Oct 2015 15:22:42 -0400) it happened Phil Hobbs wrote in :
LDRs are cool.
What I see a lot of people missing is the fact that you have to drive some motors. Using a micro can create signals for steppers or other servo types, set a timer (in case no sun) etc, do the math. Using a camera gets rid of the problems with photocells, in the case I showed (youtube) an simple very cheap PAL or NTSC camera analog output (FBAS) signal can be processed by a 2 dollar PIC.
It also depends on the horizon, where I am it is 30 degrees (trees) on one side and even higher (houses) on the other. In that case a cheap wide angle lens is enough (comes with the camera).
The alternative is use the Tomorola DNA on silicon chips, with sunflower DNA, those have excellent tracing.
Sure they are. Except when you want to do something quantitative like this.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Sigh. You don't like the clock escapement design, plywood cams, linear screw C-band dish actuators, Freon gas cylinders, gear head motors, planetary gearbox, worm gear drive, spring power, etc. Now you want me to use hydraulic actuators? Why not pneumatic, or better yet steam power? They all have the same problem... something has to provide the energy to move the panels. The amount varies depending on size, friction, wind load, number of birds sitting on top of the panels, lubrication, etc. It has to be stored somehow, and released in a controlled manner over about a 16 hr period. To do that with hydraulics is going to take a battery, electric motor, gearbox, gear pump, reservoir, hoses, valves, and actuators, as well as the usual overtravel safety gizmos. While I'm sure the steampunk people would find it "cool", I suspect the GUM (great unwashed masses) would find it overpriced, messy, ugly, noisy, and "uncool".
Yep. Elevation also had to be adjusted manually about once per month. The 555 timer drift was compensated by aligning the 12 noon position towards due south, which conveniently was always pointed in the same direction at 12 noon. I don't recall how often this needed to be done. I guess function came first, then optimization and accuracy can follow. At the end of the day, the escapement came to several missing gear teeth where it released and returned the rotating panels to the next mornings start position.
Marginally related amusing anecdote: During college, I did the electrical animation (mostly automotive windshield wiper motors) on the Cal Poly Rose floats from 1966 to 1971: For moving the rather heavy parts of the float, hydraulics was used, which worked well.
Next to our float at the Pasadena Rose Palace was a float being built by the Disney animation people using pneumatics. At the top of the float was a world globe, with an airplane circling the globe on a thin rod. Prior to adding a layer of amazingly heavy flowers to the float, the mechanism worked quite well. However, after being loaded with heavy flowers, the rod supporting the airplane bent downward and began to drag on the lower half hemisphere of the globe. Initially it wouldn't move, so the Disney people just cranked up the air pressure until it broke free. Instead of circling the globe gracefully, it lurched around in a series of ungraceful and unpredictable jumps. It could have been easily fixed by bending the support rod upwards, but the safety people justifiable vetoed any welding after the rather flammable latex coating was applied to the surface chicken wire for fear of burning the Rose Palace to the ground.
The experts played with the mechanism a little but soon gave up. We offered to help, but as nobody could agree on exactly what to do, nothing was done. So, it went down Victory Blvd as it stood, lurching and jerking around until the airplane literally fell off along the parade route. With the weight removed, the now bare rod rotated nicely around the globe.
Were a tracking solar array to be pneumatically driven in a similar manner, I can imagine a similar lurching motion as it follows the sun.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
But the political climate doesn't cause their inability to think. It's the other way around.
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