Cadence Meter Proves Wearable Development Is All About Just Doing It

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The tech involved in the fitness world really empowers athletes, whether they’re serious or not, to improve their performance by providing empirical evidence. The Striker project focuses on cadence, which is the frequency of strides when running, or revolutions when pedaling. It uses a force sensitive resistor in the shoe to measure footfalls or power strokes.

The concept behind the device is solid, and there are consumer-grade devices already on the market that are capable of performing the same functions. In fact, a Garmin device is used to help measure the accuracy of the system. But we love to see bootstrapped projects, and this one distinguishes itself not only in finished product, but in the process itself. To us it screams: “What are you waiting for, build a prototype and then iterate!”.

The larger image above shows the earliest working version which is just a piece of fabric that wraps around the forearm to hold a 4-digit 7-segment display. The wire following the arm of the wearer snakes all the way down to the shoe to connect with the force sensor. The image to the right is the first wireless version of the readout. But the project has already seen at least two more versions after this one, mostly using SparkFun components.

We think this is but one example of the kind of stuff we want to see as contenders for The Hackaday Prize. The project uses Open Design and it’s arguably a connected device because the sensor and readout connect to each other (but ideally you’d want to add more connectivy to get at the data). The open nature of the build could lead to leaps forward in the technology by affording talented people wider development access.

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Build and install your own high-end cycling power meter

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Cycling power meters can set you back quite a pretty penny. [Keith] quotes prices starting at $1500 and going up to $4000. We know several serious cyclists who would think twice about spending that on a bike, and wouldn’t even consider putting that kind of investment into an accessory for it. But if you’ve got the time [Keith] will show you how to build and install your own cycling power meter.

The link above is a roundup of all the posts and videos [Keith] made along the way. We’ve embedded his introduction video after the break where he discusses the goals of the project. The system allows for independently measuring the power of each leg. This is accomplished using strain gauges on the cranks to monitor torque. This data is combined with cadence measurements (how fast the rider is turning the cranks) which is all that is necessary to calculate the power output of the rider.

The parts list comes in at about $350. This doesn’t include the equipment he used to test and calibrate his calculations.

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Comparing Altium and Cadence PCB layout tools

We see a lot of projects using Eagle for the schematics and PCB layout. There are a few that use Kicad, but we hear very little about other alternatives. Recently, [Limpkin] has been working with Altium and Cadence and wrote about how they compare when it comes to PCB layout. Neither are free packages so it’s good to know what you’re getting into before taking the plunge.

[Limpkin] begins his overview by mentioning that the schematic editors are comparable; the differences start to show themselves in the PCB layout tools. Here you can see that Altium always labels the pads so you know what net each of them belongs to. Cadence (whose PCB layout tool is called Allegro) will display the net if you hover over the pad with your mouse. Both have 3D rendering, with Altium’s looking a bit more pleasant but what real use is it anyway? Okay, we will admit we love a good photorealistic board rendering, but we digress. The most interesting differences show themselves once traces are all on the board and need to be rejiggered. Cadence will actually move traces on other layers automatically to avoid collision with a via that is late to the party, and Altium shows some strange behavior when dragging traces. [Limpkin] doesn’t register a final judgement, but the comparison alone is worth the read.

Bike trainer computer: Speed, Cadence, Heartrate, Trainer temp

[Kurt] was using a bike trainer to get in shape for warmer and dryer biking months. Unfortunately it’s pretty hard to train if you don’t have reliable data concerning how hard you’re working. There’s commercial solutions for trainer computers but he’d read some rough reviews about them and decided to build his own trainer computer. He’s done a great job of integrating a lot of different data collection sources. He picked up two replacement bike computer sensors to use on the back wheel for speed (the front wheel is stationary with this type of trainer) and on the crank for cadence. He also wears a heart rate monitor and sourced a SparkFun heart rate module to gather that data. Finally, an LM235 analog temperature sensor was combined with a spring clamp to detect the temperature of the trainer’s resistance module.

Data from the sensors is collected with a PIC16F73 microprocessor and fed to a computer over a serial connection. He’s got a screenshot of the realtime graphs that he’s using for feedback while on the bike. This is a useful and practical setup but when he get’s tired of exercising he’s just a few lines of code from converting this into a gaming controller.

[Thanks Justin]

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