PicoRico Hacks String Encoder for Bike Suspension Telemetry

It’s simple, it’s elegant, and it works really really well. The PicoRico team built a telemetry system for a downhill bike. Off the top of your head how would you do this? Well, telemetry is easy… just add an IMU board and you’re golden. They went beyond that and have plans to go much further. In fact, the IMU was an afterthought. The gem of this build is a sensor that may go by several names: string encoder, draw wire sensor, stringpot, etc. But two things are for sure, they planned well for their hackathon build and they executed on that plan. This landed them as first-runners-up for the top award at the 2015 Disrupt Hackathon in New York, and the winners of the top Hackaday award at the event.

picorico-thumb[Chris], [Marek], and [Dorian] wanted to log all the telemetry data from [Chris’] downhill bike. One of the biggest challenges is to measure the force absorbed by the suspension on the front fork. The three had seen a few attempts at this before. Those used a retractable wire like what holds keys to a custodian’s belt, mated with a potentiometer to measure the change. This is where the term stringpot comes from. The problem is that your resolution and sensitivity aren’t very reliable with this setup.

That is a sensor problem, not a mechanical problem so they kept the retractable reel and replaced the pot with a much more reliable part. In its place an AMT203 absolute position sensor provides an epic level of sensing. According to the datasheet (PDF) this SPI device senses 12 bits of rotation data, can be zeroed over the SPI bus, and is accurate to 0.2 degrees. Unfortunately we didn’t get a good up-close shot of the installation but it is shown in the video. The encoder and retractor mount above the shocks, with the string stretching down to the skewer. When the shocks actuate, the string extends and retracts, turning the absolute encoder. Combine this with the IMU (and two other IMUs they plan to add) and you’ve got a mountain of data to plot and analyze. The videos after the break show a demo of the string encoder and an interview with the team.

picorico-packing-heavyThey came to play

It’s worth noting that the PicoRico team were in this to win it. They packed heavy for the 20-hour hackathon. Here’s a picture of all the gear they brought along with them to the event… in addition to the bike itself.

We see a solder station, Dremel (with drill press), impact driver, tap and die set, extension cords, boxes full of electronics, and more. This type of planning breaks down barriers often faced at hardware hackathons. You can download a software library; you can’t download a tool or building material that nobody has with them. This is the same lesson we learned from [Kenji Larsen] who, as part of his mentoring at the event, brought a mobile fabrication facility in a roller bag.

If you start getting into hackathons, and we hope you will, keep this in mind. Brainstorm as much as you can leading up to the event, and bring your trusted gear along for the ride.

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LEDs Strips Tell You the Trains Aren’t Running

[James] is a frequent user of the London Underground, a subway system that is not immune to breakdowns and delays. He wanted a way to easily tell if any of the trains were being disrupted, and thanks to some LEDs, he now has that information available at a glance without having to check a webpage first.

Inspired by the Blinky Tape project at FT Engineering, [James] thought he could use the same strip of addressable LEDs to display information about the tube. A Raspberry Pi B+ gathers data from the London Underground’s TfL API and does a few calculations on the data. If there is a delay, the LEDs in the corresponding section of the strip will pulse, alerting the user to a problem with just a passing glance.

The project is one of many that displays data about the conditions you’ll find when you step outside the house, without having to look at a computer or smartphone. We recently featured an artistic lamp which displays weather forecasts for 12 hours into the future, and there was an umbrella stand which did the same thing. A lot is possible with LEDs and a good API!

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Bicycle-Powered Wimshurst Machine

A lot of great pieces of real technology were inspired (or, at least, look like) pieces of technology from science fiction of the past. Like the smartphones of today have a surreal resemblance to the Star Trek communicators of the 60s, [Steve] took inspiration from a story about a bicycle racing in space and set out to make his own.

In the story, the bicycle wheels are replaced by electrostatic generators that power a type of (fictional) ion drive. Since an ion drive wouldn’t add much thrust to a bicycle operated on the Earth, [Steve] used the electrostatic generator he built to create a sparking light show. The generator is called a Wimshurst machine and has two counter-rotating discs which collect charge. The charge is dissipated across a spark gap which is placed where the bike light would normally go.

We don’t know if the sparks from the Wimshurst generator are enough for a proper headlight, but it’s definitely a cool effect. [Steve] also points out that it might also work as a bug zapper, but either way you should check out the video after the break to see it in action! While it’s not quite a tricorder it’s still a pretty impressive sci-fi-inspired build, and something that’s definitely unique in the bicycle realm.

There’s quite a collection of these Wimshurst projects beginning to come together. Here’s one made using a trio of soda bottles, and another example which used 3D printing.

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Building A Square Bicycle

Inspired by [Michael Ubbesen Jakobsen’s] BauBike design, [Aaron Seiter] decided to try building his own.

The entire frame was made out of 1″ square steel tubing and welded together in no time at all. Actually intending to ride this bike, he had to make a few changes to the original BauBike design. Most importantly, he raised the seat up to allow for proper leg extension while pedaling.

The funny thing is most people on Reddit thought it wasn’t going to work, so shortly after posting the gallery to imgur, [Aaron] also uploaded a short video to YouTube to prove, yes, he can actually ride it. Stick around after the break to see it in action.

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[Jay] turns over a new Leaf, scores batteries

[Jay] got a pretty good deal on a low milage Nissan Leaf battery. Unfortunately, it came wrapped in a wrecked Nissan Leaf. There are more and more electric cars on the road each year, and that means there are more cars coming off the road as well due to accidents. Electric cars are specifically designed to protect their batteries, so as we’ve seen before with Tesla vehicles,  a salvage car often will still contain a serviceable battery pack. [Jay] used this knowledge to his advantage, and walks us through his experience buying, testing, and dismantling Hoja, his very own salvage Leaf.

[Jay] set up an account on Copart, an auto salvage auction website here in the USA. “Live” online Auto auctions tend to work a bit differently than E-bay, so [Jay] walks us through the process of buying the car, and gives some tips for getting through the process. [Jay’s] particular car was delivered to him on a trailer. It had been rear ended so hard that the rear tires were not usable. The car was also electrically dead. Thankfully, the electrical problems turned out to be a discharged 12 volt accessory battery. A quick charge of the accessory battery caused the Leaf to spring to life – and display a ton of trouble codes. [Jay] cleared the codes with his trusty OBD II scanner, and the car was ready to drive, at least as much as a wrecked car can drive. It did move under its own power though – with the rear end riding on dollies.

Now that the battery was known to be good, [Jay] set about liberating it from its crushed Leaf cocoon. Nissan’s service manual assumes one would be doing this with a lift. [Jay] had no such luxuries in his driveway, so he used 3 floor jacks to lower the 600 lb battery and dollies to pull it out from under the car.

Click past the break for the rest of the story.

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Try Not To Fall Off The Backwards Brain Bike

[Destin] of SmarterEveryDay fame has a challenge for your brain : a bicycle where the handlebars turn the front wheel in the opposite direction of a typical bike (YouTube link). For example, turning the handlebars left turns the wheel right and vice versa. He warns you it’s harder than it looks.

The hack that pulls this off is a simple one compared to bike hacks we’ve previously covered. Gears on the head tube make this possible. It was built by his welder friends who challenged him to ride it. He couldn’t at first; determined to overwrite his brain’s memory of bike riding, he practiced until he finally succeeded. It took him eight months. When it was time to ride an old-fashioned bike, it only took him about twenty minutes to “un-learn” the Backwards Brain Bike. [Destin’s] biking illustrates neuroplasticity, memory, and learning in a fun way (fun for us; no doubt frustrating for him).

As a testament to the sponge-like brains of youth, [Destin’s] son learned to ride the Backwards Brain Bike in only two weeks.

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Electric Longboard has a Flexy Battery Pack Design

DIY electric longboards are a ton of fun to build and ride (we’ve featured several builds before). Most boards have batteries strapped to the bottom of a rigid board, or they have battery packs near each truck so the board can still flex. Instead of going with either of these designs, [Ben] created a custom battery pack design that’s able to flex with the board.

[Ben]’s pack is made up of A123 26650 cells nestled in his custom-fabricated enclosure. [Ben] designed his pack in CAD and used a CNC machine to create a foam mold. He used the mold to do a fiberglass layup, vacuum-bagged it, and left it to cure. Since the fiberglass bonded really well to the foam, [Ben] used acetone to dissolve the foam while leaving his fiberglass layup intact.

Bendy battery pack on longboard[Ben]’s pack fits 18 cells which he soldered together with some flexible copper grounding wire. The top side of the enclosure is covered with a layer of insulating rubber, and the rim is covered with a soft foam to form a gasket against the board. As you can see, the pack bends really well with the board, and  it doesn’t look like [Ben] has had any issues with his design so far. Check out [Ben]’s blog for more info and for more details on the overall design of his board.