Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
On Thursday, 4 May 2017 17:26:41 BST Ralph Corderoy wrote: > If the control logic looks like being at all complex you'll probably > want to simulate the system all in software; your control logic versus > random events/you acting as the gods. When I was writing Python, I used > its TkInter GUI library to do something similar. That provided all the > controls to control the simulation, display readouts, etc., but best of > all was its Canvas widget to draw a schematic. This lets you plonk down > bits of drawing and text, give them "tags", and then change all things > with a given tag, e.g. colour, and it takes care of the redrawing. In > my case, it was all the lines representing one logical wire, etc. > > https://wiki.python.org/moin/TkInter Thanks. I'll look into that, although I doubt that we'll be writing software for some time. We need to get the system design nailed down first and we can't do that until we've built and tested some sensors. -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
Hi Terry, > Part of the control system will include varying the amount of water > pumped from the sump to the bog garden ... > we need to know the level of water and the flow at various points > around the system. If the control logic looks like being at all complex you'll probably want to simulate the system all in software; your control logic versus random events/you acting as the gods. When I was writing Python, I used its TkInter GUI library to do something similar. That provided all the controls to control the simulation, display readouts, etc., but best of all was its Canvas widget to draw a schematic. This lets you plonk down bits of drawing and text, give them "tags", and then change all things with a given tag, e.g. colour, and it takes care of the redrawing. In my case, it was all the lines representing one logical wire, etc. https://wiki.python.org/moin/TkInter Cheers, Ralph. -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
On Thursday, 4 May 2017 16:52:49 BST Ralph Corderoy wrote: > Does the sump at the bottom of the river have the capacity to cope with > no power for the pump that takes the water back uphill? Perhaps it > overflows into a drain? If not, I guess the pump runs continously or > the river flow is shut off at the top with the bog garden able to absorb > a lot more if it's not a sudden increase? Would seem a lot simpler if > it was a closed system, not open to the rain. :-) Err. That would be a bit difficult since the attraction is completely in the open air. (Yes I did see the smiley.) The sump would flood if too much water got into the river. Historically the old system was shut off overnight or in the off season, but otherwise consumed a lot of water from the mains due to leaks. To save money and the environment, the leaks have been largely stopped reducing the water loss, but also increasing the risk of flooding. During dry periods however, a top-up will still be needed and the goal is to supply that water from the butts, with any excess being made available for watering the gardens. If the excess exceeds the demand then we will have to dump the water somehow. Of course during a real drought, we would then have to fall back on the mains. Part of the control system will include varying the amount of water pumped from the sump to the bog garden by using a PWM drive signal to the pump motor. In order to do that automatically, we need to know the level of water and the flow at various points around the system. -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
Hi Terry, > However, once the rainwater collection scheme is in place with five or > more water butts to store the water, then the risk of floods will be > increased after periods of heavy rainfall. In the end, the monitoring > and control is more about that scenario than the present one. Does the sump at the bottom of the river have the capacity to cope with no power for the pump that takes the water back uphill? Perhaps it overflows into a drain? If not, I guess the pump runs continously or the river flow is shut off at the top with the bog garden able to absorb a lot more if it's not a sudden increase? Would seem a lot simpler if it was a closed system, not open to the rain. :-) Cheers, Ralph. -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
On Thursday, 4 May 2017 16:20:48 BST Patrick Wigmore wrote: > I must admit, it surprises me that the river system is so > sensitive to the weather conditions. I would have expected there > to exist a constant pumping rate that would maintain the river > between sensible high and low levels except in very extreme > weather. Well, before this year, when the bog garden was added, this is exactly what happened, except the volunteers or staff had to top-up the system to compensate for leakage and evaporation. Floods were quite rare, because the catchment area was very small. > But then I have assumed an 'ideal' river and sponge-like bog, > both with no leaks into the ground, and a sump tank that can > easily hold the entire volume of water when the pump is switched > off and the system drains down. It sounds like the reality is > more complex. This is the first year that the catchment has increased due to the addition of the bog garden, but even that won't make a lot of difference I suspect. However, once the rainwater collection scheme is in place with five or more water butts to store the water, then the risk of floods will be increased after periods of heavy rainfall. In the end, the monitoring and control is more about that scenario than the present one. -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
On Thursday, 4 May 2017, at 11:29:27 BST, Terry Coles wrote: > Since the system will be running largely unattended 24/7, we > want to be able to predict the onset of a flood or drought in > the river. To do that we need to measure the actual depth so > we can determine the rate of change. I must admit, it surprises me that the river system is so sensitive to the weather conditions. I would have expected there to exist a constant pumping rate that would maintain the river between sensible high and low levels except in very extreme weather. But then I have assumed an 'ideal' river and sponge-like bog, both with no leaks into the ground, and a sump tank that can easily hold the entire volume of water when the pump is switched off and the system drains down. It sounds like the reality is more complex. -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] A New Wimborne Model Town Project Query - Sensing Water Levels and Flow
On Wednesday, 3 May 2017 18:15:34 BST Andrew wrote: > In case you didn't already know, 'digital' versions of these are > available quite easily and probably cheap, or free. They are used in > most if not all washing machines and dish washers. The one I've looked > at recently has a screw for pressure adjustment. You could get hold of > at least two of them (one for "too high" and one for "too low") and > connect them to GPIO pins if exact water height doesn't matter. Since the system will be running largely unattended 24/7, we want to be able to predict the onset of a flood or drought in the river. To do that we need to measure the actual depth so we can determine the rate of change. We can do that a number of ways; an air pressure sensor for depth; a load-cell for weight or an ultrasound detector for distance to the surface are all under consideration. They will all will give a linear output between empty and full. We have considered a cluster of probes to signal when various levels are reached, but we currently prefer the pressure, weight or ultrasound approach to give a continuous reading. (This will also be better for the educational side of the project, since the Visitor's display will show the actual levels and flow around the system.) > If the problem is making sure the water is pumped from the lower tank to > the header tank, but the pump is turned off when the header tank is full > or the lower tank is empty then there's some quite simple ways to do > that. But they don't require a computer so aren't perhaps technical > enough for this list. :) It is more complicated than that. Not only do we want to control the pumping of water to the header tank (the bog garden), we also want to control the flow of water in and out of the butts. > Also, I wrote my last e-mail before I had looked at the Wimbourne Model > Village web site. I imagined it would be indoors and a lot smaller than > it is! Yes. The Model Minster is too tall for me to work on the Quarter Jack without a ladder! -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
