outdoor fountain control

Hi,

I'm designing a water display for a disabled persons garden. The idea is to have 3 fountains under a gridded walkway. As a person is pushed along in their wheelchair the 1st fountain would be switched off. As they pass over the top of it and past to a suitable distance (2m) it would be switched back on and the next fountain swicthed off (& so on...). The walkway will be oneway only.

What would be the simplest logic to control such a setup?

Thanks,

Use infrared long range photo electrics to detect the "on" and "off" points. Programming is then pretty simple.

I know how not to do it.

I built the panels for some of the water features in a shopping mall a while ago. One of them was a pond with lilly pads separated by fountains, and frogs spitting jets across it. The pads just had limit switches underneath, and as you walked from pad to pad, the fountains parted to let you through, and the frogs stopped spitting. I programmed it so stepping onto the pad opened the next fountain, and put a delay on stepping off to return the fountain to normal.

It didn't turn out very well, because people were determined to go the wrong way, kids lined up three at a time on the edge of the pond to jump onto the pads, which broke the switches, the floor where you stepped off was polished wood, so as you stepped off with wet feet you went base over apex. I don't suppose you will have these problems in your case. Plus they wouldn't pay us to commission it properly in the first place.

I also did a fountain which was outside. It shut down whenever the wind speed went over a certain amount, but there were buildings close by on three sides. So, where do you put the anemometer?

An outdoor motion detector, or a retro reflective eye would both work. If you go the route of the eye then use the "light on" type or function. When you loose the singnal due a dirty lense or power loss this will trigger your fountain to stop. Which sensing device to use it contingent on the availability of placement configurations.

ATC makes good photoeyes: We use a Beamwitch 7263A4X4FRX on our gate to our parking lot. http://automatictiming.com/pages_atc/sensors-self.html#7260

Here's a motion detector: http://www.smarthome.com/7488a.html

ADI sells all sorts of outdoor photoeyes and motion detectors http://www.adilink.com

I's suggest a layout showing the position of the eyes and water nozzels, water stream etc, and start with that.

Could be a little more involved than you think....What if two (or three, or four, or five, etc) people get pushed through one after the other. You're trying to control a timed sequence, yet have no control over the source of the timing.

Skycatcher,

What would be the simplest logic to control such a setup?

Click to expand...

The logic will be very similar, whether you use manual switches, relays, PLCs, or a computer, to control the fountains. "Logic" refers to the fundamental prinicples. However, the physical equipment and wiring will be different.

I would use an Automation Direct Dl-105 PLC, with 120 volt AC inputs, and PLC "relay" outputs controlling the Pump Motor starters. Use 3 photoswitches to detect the wheelchairs, as follows:

PS#1 turns off Fountain #1 as a wheelchair approaches;
PS#2 turns off Fountain #2, and turns on Fountain #1 again;
PS#3 turns off Fountatin #3, and turns on Fountain #2 again.

Mount the photoswitches on the walkway, aimed across it. In your logic, you may need other bells and whistles also. You may want a timer that shuts down all fountains if PS#1 has not been triggered for some time, say 30 minutes. Also, what if a disabled person gets part way out the walk and has an emergency (go to the potty, heart attack, etc.), and needs to go the wrong way on the one-way bridge? You may need to add emergency stop switches along the walk so the person pushing the chairs can shut down the fountains as needed. It will be more efficient to make the PLC the main controller for the fountains also. You need to consider if the fountains are to be operated even if the walkway is not in use.