Replies to This Discussion

3D RoboticsPermalink Reply by Chris Anderson on June 7, 2010 at 12:43pm

It looks awesome, but you still need to get the data out to drive servos and interface with other sensors. Apple doesn't make it easy to access the hardware port.

I bet you could use Ari Krupnick's PPM audio-out app to get data out, but how to get data in??

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Permalink Reply by lionel on June 7, 2010 at 1:14pm

From the back of my mind, there is the Apple's External Accessories framework for this. It works via bluetooth or the dock connector, both for Input (inputStream) and Output (outputStream). It is supported since iPhone OS 3 Attached the documentation from this framework.

Attachments:

• ExternalAccessoryFrameworkReference.pdf, 251 KB

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Permalink Reply by lionel on June 7, 2010 at 1:17pm

Forgot to upload the Cocoa Streams programming guide :-)

Attachments:

• Streams.pdf, 219 KB

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Permalink Reply by Ari Krupnik on July 10, 2010 at 11:54am

That video is a joke. You can read in the guy's YouTube comments what he's actually doing, and he calls it a prank. He's a good sport about it though and quite funny.

You are right that any "external accessories" require a special authentication "co-processor" from Apple, which you can only buy if you are an MFi licensee. Even bluetooth devices need that chip if they want to play the iPhone game.

The MFi program is an experience to get into. If you think releasing an app in app store is a challenge, it feels like an easy, no-surprises process comparing to MFi. Now that I'm in, my NDA prevents me from talking about the technical details publicly. But it's doable, and if you want to work on this project, let me know what your level of interest is.

Ari.

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Permalink Reply by Mike Ornstein on June 8, 2010 at 5:44am

I too am interested in using the iPhone4 as a central component for a UAV platform. If it is possible to interface the iPhone with four speed controllers, and the sensor data is decent, I feel like you can't go with such a capable device. Are there specs available anywhere that describe the quality of the integrated inertial measurement stuff in the iPhone4? If it turns out that the output from the gyros and accelerometers (and magnetometer) are good enough for stable flight (a hover in my case) I am confident I can assemble a crack team of programmers to get the software side of an iPhone4 based UAV up and running, tuned for use in a multi-rotor setup.

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Permalink Reply by lionel on June 8, 2010 at 6:30am

Just wait a little bit, there are websites which systematically open Apple Hardware and make an inventory of all the components. Another benefit of having an iPhone on.board is the data link, much faster than zibgees and, in Europe at least, it is almost impossible to find a place without mobile phone coverage.

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Permalink Reply by Xander on June 9, 2010 at 4:04pm

Close, but I'd say the price is still a bit prohibitively high (without contract) and I'd rather not have to deal with Apple's closed system. Hopefully this will push more phones to have gyros. In a year or two I expect we'll start seeing dirt cheap Android phones (under $200 without contract) with most if not all of the same features. Then we might really have something that can compete as a cheap autopilot.

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Permalink Reply by Mike Ornstein on June 9, 2010 at 8:41pm

For US based people (such as myself) the iPhone 4 starts at $200 with the contract bottomed out at $55 a month... if it's sole purpose in life is to live in a UAV then I agree, it's a bit steep. However, should the device be used in the typical way as well (as a phone), then that contract cost doesn't hurt as badly. I guess I'm just trying to justify getting an iPhone for myself... Android's definitely going to be the way to go. In regards to Apple's closed system though, I do suspect you would gain enough access via jailbreaking if you couldn't get at the necessary goods without doing so.

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Permalink Reply by Mike Ornstein on June 28, 2010 at 4:55am

So I've done a little further research, which has gotten easier since the phone has actually been released, and have found out a little about what's going on with the gyro in the iPhone 4. From iFixit's Teardown:

"...the AGD1 is the new 3 axis gyroscope that we believe is designed and manufactured by ST Micro for Apple. The package marks on this device do not appear to be the currently available commercial part, L3G4200D. The commercial version of this gyroscope is yet to be released — Apple got first dibs on it."

The commercial part of which they speak can be found on st.com. I don't imagine the one on the iPhone to be any worse in terms of resolution or accuracy, so I figured someone more familiar with the necessary specs could check out that datasheet. I've attached it for convenience.

Attachments:

• 17116.pdf, 805 KB

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Permalink Reply by Mike Ornstein on July 9, 2010 at 5:43am

So it turns out that the L3G4200D is the correct gyro. It has selectable range sensitivity: ±250/±500/±2000 dps and is manufactured by STMicroelectronics.

Can any experts on the subject confirm that those specs are adequate for stable flight?

On another note, communications are solved. The iPhone can do two-way communication via serial using the dock connector so speaking to any standard microcontroller should be no sweat. It is necessary to have a jailbroken iPhone however. Here's a serial comm tutorial for the iPhone I found.

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DeveloperPermalink Reply by Michael Smith on July 15, 2010 at 9:44pm

The iOS platform is not a good choice for the compute element in a UAV.

The iPhone/iPad/iPod Touch are designed as user-oriented consumer devices. There are aspects of the system (messaging, for one) that are directly at odds with what you want in an embedded controller.

OTOH, you could make a pretty mean base station with an iOS device.

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