This Instructable starts with a previous project - to build a single pressure pad - and then takes this further to show how this simple tech project can be expanded to make an entire playground digital!
This technology exists already in the form of 'Force Sensitive Resistors' (FSRs), yet these are often really small - no bigger than a coin to about as big as a few inches square, and usually designer for small, sensitive interactions - so are hardly big enough for an outdoor experience. This Instructables is about making this small, fundamental technology MUCH BIGGER so that it could be applied to an entire playground!
History of Pressure Pads --> Digital Playgrounds
The project began as part of a project with BBC's Big Life Fix Team. A team of UK designers, engineers and technologists were gathered to help various people with disabilities, using tech. I was involved in helping a young boy, Josh became blind from Norrie Disease, and was less able to play at recess periods in the playground.
We realised that because Josh could not navigate to where he wanted to go, he could not 'meet up by the tree', or 'walk over to the swings, to talk to his friend', as he had no bearings. We solved this by creating tactile paving roads, which were called by the kids 'yellow brick roads' - which played sounds at either end, so over time Josh was able to build up an 'audio navigation map' of where key features lay, based on 'roads' having different sounds assigned to them.
For example, he might know that the swings were at the end of the road which plays a 'tiger roar', or his friend wants to meet at the bench by the 'whale song road'. Furthermore, if Josh was not sure which end to go, he had 'hubs' (which function a bit like Roundabouts/Traffic Circles), allowing him to choose routes to walk along, with the textured tiles being able to be 'read' through the soles of his feet - a bit like 'braille for the feet'!
Of course it was great to help Josh navigate, but to really make the design 'inclusive', we realised that we needed to make it special for his friends too. We realised from early tests with kids, that jumping around on tiles that play sounds was simply fun. We took lessons from game developers and incorporates 'special moves' into the audio system, so that like Dance Dance Revolution - a special sequence of jumps/presses on the pads would 'unlock' secret audio tracks.
The octangular 'hubs' (shown here) and visual nature of the design also meant that it was appealing to sighted kids, so that there was less stigma attached to this being a marginal or solution only for Josh - it was fun for everyone.
Building Upon This Instructable
We had a lot of fun working on this, and hope that the Instructables community is fired-up about this, and will take it to new places. This Instrucable shows many of the design, tech and installation considerations - though it would be hard to make a exhaustive Instructable for a project which will of course vary from playground to playground. You may not have funds to dig up tarmac/asphalt, but this would work under a cheaper surface like AstroTurf for a fraction of the price, (see next step).
Please note that this is a V1.0, and of course many things could be improved upon, or simplified, but as a first attempt it proved that the interaction was fun, and that spaces can be designed to be incisive to all, not just creating solutions which single-out those with a disability. This in my opinion is one of the best aspects of the project, and we'd love to hear of any other community projects which have similar aspirations.
Should you wish to support research into curing Norrie Disease, visit: https://norriedisease.org.uk/get-involved/
Step 1: CONTENTS
How best to use this Instructable...
As mentioned, this is a huge project, which I'm not expecting anyone to casually duplicate on a weekend! That said, I think it does still have some essentials which would be formative, inspirational or foundational research - which can be adapted to your own needs, creating playful interactions at scale. We hope if nothing else, that the awareness of inclusive design is raised, and this is a compelling example where helping people with disabilities neither requires them to be excluded, and is fun for people of all abilities.
I've divided it up into sections for ease of navigation:
ASTRO TURF NOTE
I'm aware that it is not practical to dig up Tarmac/Asphalt, so this is a more plausible installation and/or retrofit which would be do in many playgrounds.
- How to make one (see previous Instructable).
- How to calibrate one for your installation (tips and tricks).
- How to Install (if doing it in solid ground).
- Tips on speakers & amps
- Cabling considerations.
- Hubs or other central navigation points.
COMBINING PAD INTERACTIONS
- How to set up a single pad with TouchBoard (essentially a Arduino UNO + mp3 player).
- How to cotrol multiple pads with Arduino MEGA.
- Notes on TouchBoards, etc.
INCLUSIVE PLAY EXPERIENCES
- Reflections on project.
Step 2: FOREWORD - What If You Can't Dig Up Asphalt/Tarmac?
It's fair to say this is a very large scale project for Instructables, and I can appreciate it may seem too audacious to simply assume people will 'just do it' in their local school. However, I have a couple thoughts as an aside, before we get back to the project for Josh...
INSPIRE YOUR ARCHITECT:
Schools often have work done on their playground, due to repair, or perhaps they have a grant in the pipeline for a resurfacing. Although this will of course increase cost, it's worth suggesting this would be a welcome addition to planned improvements, and so may not be so costly. Also, an architect may take a look at this *prototype* and be able to improve upon it. After all, this was a V1.0, and is an ongoing project...
Many schools have done away with grass, for the fact that it is less muddy, and can be more practical. Although I personally lament the loss of a natural feature, this cloud may have a silver lining - that it will be very easy to either incorporate pressure pads under Astro Turf, which is essentially like a big carpet, or retro-fit it to pre-existing Astro Turf with relatively little disruption - and certainly no need to excavations of the kind we undertook on this project! Examples above, show it can even be landscaped effectively, and has huge potential for playful experiences.
Clearly we had a unique opportunity to 'go big, or go home' with the joined forces of BBC, Children in Need and Mace Group to make this a successful first project. However, one could consider a smaller installation and if it helps prove the validity of the idea in your community play area / school, then perhaps it can be extended. Councils often have to be wary of new initiatives, (and this is fine), but it allows incremental improvements to make spaces more inclusive, rather than an 'all or nothing' approach. Good luck!
Step 3: Making & Calibrating Pressure Pads (DIY 'FSRs')
As mentioned, this is a DIY form of Force Sensitive Resistor. I've not duplicated this here, but you can make it here, in any size you like. (LINK). Jump to STEP 10 for the tech on electronics/code.
Now that you have your pad made, it is worth exploring what the resistance of the pad is. The resistance can be increased by increasing the amount of Velostat (a film which is insulating at low-no pressure, but under compression conducts)
The 3 images here show for 1 layer of Velostat between 2 sheet of copper.
It gave resistances of:
1. Pad at rest = ~40Ohms
2. Pad with firm pressure of resting my hand on it = ~18Ohms
3. Pad with high force pressing down = goes to zero resistance.
SETTING RESISTANCE WITH LAYERS OF VELOSTAT
If you look at the next tile experiment, with 2 layers, this went from 40Ohms to 85Ohms, and 3 layers was around 110-120Ohms. So fair to assume for a tile of around 200x200mm square, it has a resistance of about 40Ohms per sheet of Velostat.
What this tells you is that if you wanted the pad to 'trigger' with a firm press, then this is probably worth tuning to 'ignore' 40-20Ohms, and to 'switch on' when between 19-0Ohms. For a small display to be operated by light forces like fingers, this is fine, but a playground with a 1kg tile glued on top, and with kid's feet jumping on it, then it lowered the range to about 70Ohms, so the trigger range was more like 'ignore' 70-40Ohms and trigger between 39-0Ohms as a valid 'press' signal.
It's worth pointing out that the other reason we added 3x layers of Velostat was to give us a trigger range from 20Ohms to 40Ohms, which mapped better (using trim pots - see previous Instructable), and means that the pads would not play sounds at the slightest touch (e.g. a roaming cat), and would not go off because of fluctuations in temperature. The second potentiometer helps us calibrate this also.
Step 4: Endurance Testing: Heat, Water, Impact...
As you can see from my fashion-crime (socks 'n' sandals) picture; this is my back garden where I had poured a small batch of asphalt/tarmac*, so that I could glue the textures tiles down, on top of the Pressure Pads. This shows the dynamic range from 70-0Ohms.
This allowed me to test for heat (I had a blow torch // ice water), and ingress. And even abusive treatments (hitting with a hammer). I would not suggest you have to do exactly the same, but it's worth considering what may make your pads fail, once installed.
I also poured some concrete, as some of the school also had patches of different surface.
*Tip - add plastic liner, unless you want it stuck down!
Step 5: Notes on Batch Production of Pressure Pads
As mentioned in the previous Instructable, it's worth creating templates for 'batch production' of multiple Pressure Pads, as it can save a lot of time.
Although you may be happy stacking them simply, I would suggest that on a building site, it can be pretty rough - so it was a good choice to get container boxes to keep the pads safe from any knocks or punctures.
Step 6: Rehearsal of Pad Installation
As this project was produced with Children In Need special (LINK), the BBC were able to request charitable donations to help achieve this project. One such company was Mace Group, (who built the Shard!) to help. It was great working with them, and here you can see how we prepared the 30 Pads...
- Pads were read to go.
- Adhesive was applied to the back of the tile (not all the way to the middle).
- Pad was applied.
This is an example for the builders, so is stuck to a plastic sheet. Worth doing for reference though!
- Trenches were dug, with all wires installed in pipes.
- Tarmac/Asphalt overlaid.
This was a huge learning curve, as most of the team has done little more than some home DIY, so this was a real experience of how groundworks were carried out professionally.
Step 7: Getting the Professionals In: Gallery of Groundworks
Some images of work done on site. I personally find this useful, as not only does it manage expectations of what a designer should expect when designing for installation, but also how things will transpire with breaks in schedule, inclement weather, slight changes in equipment or materials. All of this is about designing in 'tolerance' to cope with such eventualities.
- The 'Plan', which of course never goes entirely 100% to plan! And adaptations need to be made on the go.
- Early groundworks (digging up trenches).
- Clever use of pipes to allow familiar installation methods wherever possible (even when Mace had never done a 'Digital Playground', one might suppose 90% was still very familiar practice to them).
- Pulling literally hundreds of meters of cable through pipes!
- Testing fit and location of Pads.
- Connecting to Speakers.
- Filling back in. Adding Yellow Pads to finish!
Step 8: Speakers & Amps
Given that you are wanting to keep your dynamic range (how many increments of resistance (Ohms) you can get for one press) as large as possible, the wires are a part of the system, so choose a thick cable as possible.
Here you can see a 50m of cable is 0.7Ohms - so this is negligible. You'd be fine with 5Ohms probably, but we had industrial audio cable for the speakers, so simply used that here also.
We used marine specification speakers, as it was outdoors:
Bass Face SPLBOX.3B 600 W Boat Patio Outdoor Garden Marine Waterproof 2.
Installation can be done on posts, or on walls, as shown.
As we were only driving quite lo-fi sounds, a saller amp could be used, like this:
PCAU22 Amp (LINK). As seen later, I suggest housing large numbers of Amps in a cabinet for safety. In hindsight (and at more expense the we had budget for at this point) - you could also use a dedicated MIDI system to manage this, but this was a quick solution, and at about £25 per amp, it was fair.
Step 9: Design of the Hubs
The hub was a welded steel construction, as shown in green. The speakers were placed equidistant, around the 8 sides of the Hub. The holes were later covered with mesh, and the final assembly was painted.
Care was taken to allow easy access for adjustments - this being a V1.0 prototype!
The reason there is 8 speakers is so as to allow Josh to hear which direction a sound is coming from. Even in a busy playground, one can tell where the direction of the sound is coming from - and hence which road Josh would like to navigate towards.
Step 10: Electronic Control: Arduino MEGA & TouchBoards
- The plan shows that there are 2 groups of controls:
1. PERIMETER SOUNDS (in Blue), which are around the edge of the playground.
These have a Shield (blue colour) on top of them, with trim pots onboard.
2. HUB SOUNDS (in Green), are 2x Hubs, each of which has 8x Pads.
These are controlled by Arduino MEGAs, and these are connected to 8x TouchBoards (without Shield).
The trim pots are on a MEGA Shield for convenience.
- The Red Control Panel layout.
This shows the layout of all the boards for reference (but you can of course arrange them any way you like - the key point being you need to connect the controls to the various pins of the MEGA from the TouchBoards to play the music).
- I've included images of the Shields - first the one for the TouchBoard, and second for the Arduino MEGA.
- The sketch of the wiring diagram shows the approx. pin assignments, but it's best to follow the comments in the .ino file for this, and indeed, you may be assigning a very different arrangement, so this is but one approach you could take.
- Code (for Arduino - works for MEGA and TouchBoards). Attached
It's worth saying, this is very much a prototype, and its' quite unlikely that you'll be simply transposing this whole project line-for-line, so naturally it will change according to your on composition and design. Although not exhaustive as an Instructable in terms of the code, I hope that it is still representational of what is a viable option. Do post any question below =)
Step 11: Installation (under the Stairs!)
This part never made the TV show. Given that on Instructables, we are among fellow makers//geeks/etc. - I thought I'd share some of the gritty reality from 'the cutting room floor'...
Thanks again to Sam, who along with myself and Ruby, spent 3 long days under the stairwell in the school, hunched like Gollum over our 'precious' electronics. Much of our conversation on phones consisted of "ok - jump on the pad" / "did you get a reading?" / "erm...nope...try the one next to it" / "yep - I'm on it" / "ah, crap, ok, let me check the wiring diagram again...let's try Pad #10..." / "*sigh*". Be ready for a lot of back and forth with this sort of thing. In hindsight, I can see how this particular phase may not have made gripping TV!!
Take away from this Instructable is to buy a professional installation rack; as if anything were to go wrong, the power shuts off, and it does not burn the building down. Always get a professional to check over any work like this. (I was pleased that we had no serious adjustments, and only a few suggested upgrades, but the peace of mind is worth any extra fees to have it totally safe for public and anyone working on it in future).
Step 12: Inclusive Navigation: Yellow Brick Road & Hubs
You can see from the detail here, that there are two types of pads:
DOTTED - means 'stop' and this was where the sound played.
STRIPED - this means 'walk in line with these stripes'
These are typical tile textures used on public roads, so were in-keeping with Josh's expectations and experience - just applied to a very different setting!
Step 13: Children in Need // the Big Life Fix
The final project was broadcast as part of BBC's Children in Need programme. It was remarkable to see Josh take huge leaps of faith (even at first encounter) to work unaided, navigating by the 'sound' assigned to the particular road/path he was on, and being able to 'read' like braille with his feet, where he was going. The Hubs allowed him to change direction, and of course the Hubs soon become a favourite inclusive game with all the kids to 'unlock' the secret sounds by jumping in sequence!
Pressure Pad Instructable (LINK)
BLF Review: https://www.imdb.com/title/tt6463886/
The TV show is available on BBC for a limited time, but *ahem* might be on YouTube for international audiences also ;o)
Many thanks to all the amazing team at Studio Lambert, BBC, CiN, Mace and many others involved! For more info on other fixes (LINK). Please give a vote/like/share if you enjoyed this - we hope it inspires future projects.