User dispatch system

[Jordiieeb]

Hey guys,
I need help with a project that i want to build. So at my river side house we have a pretty big hydro slide that we made and we are letting all the holiday goers use it when they are at the park next door. So what i want to create is a user dispatch system. Eg. Rider gets to the top of the slide and there is a green light on telling the rider the slide is clear to go down it. The rider enters the hydro slide and passes a sensor, turning the green light to red. Red light tells another rider that the hydro slide is occupied. When the rider on the slide is near the bottom he/she passes another sensor turning the red light back to green telling the next rider that the slide is clear to enter. And it rolls out like that. Can you guys help me to make this an in expensive system for me to make as i dont make a profit off the hydro slide. Also if there is a way to add like a pause button onto the system so that incase of an emergency at the bottom of the slide, we can pause the system so that we dont have to worry about anyone flying into us.
Thank you so much! Please please help me!
Thanks!
Jordan

 

[alec_t]

Welcome to ETO!
That's very generous of you to give free rides to all and sundry. I hope they appreciate it and that you have good public liability insurance!
One safety issue that occurs to me: can you prevent people larking about near the foot of the slide and accidentally (or intentionally) triggering the lower sensor and thus giving a false indication that the slide is clear?

 

[tunedwolf]

Most of the older commercial systems that I worked on in the past used capacitive proximity sensors molded into the GRP, however, the new systems now use small cameras that detect image changes. The early control systems were very simple logic and timer type affairs, the later ones now use custom DSP's and Microcontrollers

 

[Jordiieeb]

Welcome to ETO!
That's very generous of you to give free rides to all and sundry. I hope they appreciate it and that you have good public liability insurance!
One safety issue that occurs to me: can you prevent people larking about near the foot of the slide and accidentally (or intentionally) triggering the lower sensor and thus giving a false indication that the slide is clear?

Yea so what i have seen previously is the sensor being about 1 metre up the slide from the end of it if that makes sense?

 

[KeepItSimpleStupid]

Here https://electronicdesign.com/analog/driven-shield-enables-large-area-capacitive-sensor is a place to start.

What material is the slide made from and how thick is it where ones butt goes?

 

[tunedwolf]

Here https://electronicdesign.com/analog/driven-shield-enables-large-area-capacitive-sensor is a place to start.

What material is the slide made from and how thick is it where ones butt goes?

The ones I have worked on were usually 1/2" thick GRP with a 1/8th Gel coat finish. Sections are flanged and bolt together with Neoprene seals between them. The proximity sensors are most often fitted 1M up/down on the slope, never at the entry point or exit points. Multiple sensors are used at each location to guarantee triggering of the traffic lights.

 

[AnalogKid]

Sounds like a light beam sensor system to me. Industrial waterproof critters are off-the-shelf, but probably pushing $100. This is a well-defined situation where I think you could whip up something and glop it in RTV. High intensity red LEDs have narrow beam angles, essentially pre-focused over 1 m. 555 oscillator and a very basic frequency discriminator to weed out sunlight and reduce false hits. Two sets, a couple of logic gates (or a uC), and the traffic lights and you're there.

ak

 

[Jordiieeb]

Sounds like a light beam sensor system to me. Industrial waterproof critters are off-the-shelf, but probably pushing $100. This is a well-defined situation where I think you could whip up something and glop it in RTV. High intensity red LEDs have narrow beam angles, essentially pre-focused over 1 m. 555 oscillator and a very basic frequency discriminator to weed out sunlight and reduce false hits. Two sets, a couple of logic gates (or a uC), and the traffic lights and you're there.

ak

Thanks for that sounds good, could you just give me an instructional way of making this? Like step by step on how to put it together and how to make the logic gates work with the light beam sensor? Thanks J

 

[tunedwolf]

The primary reason why light is not normally used, is that in order to guarantee triggering, they have to be fitted low down in the slide. Water diffracts the beam as it swishes around and causes false triggering. A light curtain might be possible though, if you have a way to choose the number of beams broken before triggering is acknowleged. Apart from that, health and safety, at least in the UK, but likely everywhere else too, dictates that there are no protruding objects within the entire tunnel length, and that the tunnel walls be super smooth and without anomalies, so holes would need to be cut and the light sensors sealed in such a way as to not protrude and not disrupt the smooth surface finish. Then there's the water treatment to think about, chlorinated water just loves to munch on stuff, so whatever you do, your solution must stand up to that as well

 

[KeepItSimpleStupid]

tw:

Definitely glad you brought all of that up. Redundant capacitive proximity seems like the only technology that could work, but I like the video motion sensors too.

 

[Blueteeth]

Maybe I'm late on this one but beam breaking can be very effective, as it can be sealed from contaminants, uses off the shelve (read: cheap) parts, and with multiple beams can help prevent glitches - several beams must be broken at the same time, for a certain period in order to register a 'hit'.

There is also the very basic mechanical switch (which could in fact be a small IR interrupter sensor broken by anything that blocks light) that detects the weight of a person.

Capacitive proximity sensors can be extremely simple or very complicated depending on the application, and level of safety/protection required.