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September 4, 2008
News - Project interview: Mechan…
about a month ago
Thanks for replying.
I didn’t suggest to actually use pyros, that would probably not be a good idea for multiple reasons (imagine it firing around spilling fuel, even though the patrones are actually enclosed in a real pretensioner). There are several types of these pretensioners around - the one using a pyropatrone that activates in the case of crash (similar to airbags and controlled by the same system), then ones using electrical motors and finally a purely mechanical one (the oldest system) using springs. The point is to minimize electronics and moving parts to minimize the points of failure. That is where the seatbelt pretensioners as an inspiration for the design could be a good idea.
Re mass: careful, I was speaking about moving mass, not the static weight of the device (which is, indeed, supported by the shoulders). The moving mass comes into play when you have strong accelerations, especially lateral ones. The mere mass of the helmet is the reason why drivers specially train their neck muscles because otherwise they wouldn’t be able to cope with the enormous centripetal forces produces by the helmet while cornering - that is the reason it is “frowned upon” in open wheel racing. In rallying the forces are smaller, but it is still significant, especially in a case of an accident like a rollover. So adding extra stuff in a place where it could add to this mass is a really poor idea.
One solution would be to displace the electronics and have it linked with a lightweight actuator on the HANS by a cable with a quick disconnect connector. The drivers use cables for their helmet microphones/headphones, intercoms or even medical sensors already, so this could be integrated with that in order to not require additional cable to be removed in an emergency. I would also move the (relatively heavy) actuators down, lower on the driver’s back, closer to the driver’s centre of mass, reducing the leverage it produces on the neck. That would need some engineering in order to keep the driver safely in the seat and comfortable, though.
Nice project, but this is basically a re-invented seatbelt pre-tensioner. Moreover, those are functionally quite a bit simpler, some even using pyrotechnics to tension the belts in the case of an impact - very important for a safety critical device. The fewer things that could fail, the better.
Also, you certainly don’t want to put anything of a significant mass on the driver’s neck/head. At the accelerations the race car drivers experience during the race this could be a major liability because it becomes a heavy “rock” tied to their neck. That would increase the strain on their neck muscles and potentially risk injury (you certainly don’t want your safety device meant to prevent the driver from breaking their neck to actually break their neck …). There is a good reason for why HANS is so mechanically simple - the mass of the device is of a paramount importance.
about 7 months ago
Pity that it is the old version and not the newer one like this one:
They are shielded (good idea for an RF device!) and have a lot more I/O pins broken out - the module has a full featured OS and for simpler applications it can function completely standalone (there is a free toolchain available for it), without another MCU. But it sucks when you have only about 2 available I/O lines.
Whether the module costs $2 from China and it takes a month or two to get it (if it arrives at all) or whether it costs $7 from SparkFun and you get it quickly and reliably is up to you to decide whether it is worth for you.
News - According to Pete #41: Bo…
about 8 months ago
The problem is that even that could run afoul of the rules - some bozo will connect a longer wire as an antenna to it and it is over the 50nW ERP that is allowed here in Europe. And you can certainly exceed 50nW even with a single transistor running from a battery, no problem at all. At least we have got the 50nW now, it used to be completely verboten before - so no FM band “bugs” or streaming music to an old car radio for us.
If people want to experiment with radio transmission, it is better to get a HAM radio license. Even using the ISM bands may not be legal, because the equipment is not certified (obviously, when it is homebrew).
You aren’t very likely to get caught unless e.g. neighbours complain of interference or you cause interference to some important equipment (e.g. airport, emergency services, etc.), but if you do get caught, the fines are very stiff and there may be even criminal prosecution. I don’t think it is worth having a criminal record because of a stupid learning experiment.
Teaching people to flout the rules is just wrong. At least make them aware of the restrictions - you cannot prevent people from being stupid but you can make them not be ignorant.
Pete, if you are planning to make show something “FCC may not be happy about” - such as a wireless microphone - do mention the rules, please. Especially in Europe building stuff that transmits in bands like the FM radio band is pretty much verboten unless very strict power limits are followed and hefty fines are possible. I believe the US rules are more lenient, but you have also overseas viewers/customers.
News - FTDI Drivers and Counterf…
That patch is legit - signed off by the maintainer of that subsystem. They really are that dumb.
I don’t see it getting merged, though.
WTF: “This is definitely not targeting end users - if you’re unsure if
ICs are genuine then please don’t use the drivers.”
These guys are so full of it …
Actually, they don’t attempt to identify the counterfeit chips. They just blindly change the PID exploiting an implementation difference between the real and the cloned chip. The real one will ignore it as invalid, the cloned one will brick itself :(
Really really nasty hack:
News - Arduino Trick: Double Upl…
about a year ago
That is not correct - CRC is done only by USB and the bootloader, verifying that each packet of the data is not corrupted. Which won’t protect you from e.g. failing flash. There is no “CRC after upload” and the article never said anything like that neither.
The post-upload verification works by downloading the flash and comparing byte by byte with the original hex file. If it doesn’t match, verification error is raised. Of course, that works only if you keep that “verify” switch on.
Bootloader CRC won’t protect you when the chip’s flash is not erased or failing. It protects you only from data corruption in transfer (e.g. due to noise). And even that isn’t infallible - the checksumming is usually fairly rudimentary.
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