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What type of microcontrollers (in terms of processing power, clock speed) are used in large scale UAVs such as the Northrop Grumman RQ-4 Global Hawk, the General Atomics MQ-1 Predator etc. ?

Also, are smaller, low powered microcontrollers used for controlling subsystems such as the INS and control surface movements. If so, then in what range does their processing power and clock frequency lie?

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  • $\begingroup$ I think this information is likely to be classified, at least for the specific models referenced. $\endgroup$ – TypeIA Jun 15 '14 at 16:05
  • $\begingroup$ Yes, thats likely to be the case, however i am looking for a range of parameters for microcontrollers used in large scale UAVs. $\endgroup$ – Pranav Jun 15 '14 at 16:22
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Airbus used standard Intel 80186 and Motorola 68010 CPUs with 2.5MiB of memory in the FBW system for A320. Exactly the same chips that were used for computers at the time (around 1985) so they were not expensive and were already tested. Over time they upgraded to newer version of those CPUs. Each computer is composed from two boards with different CPUs, one produces the control output and the other verifies it and shuts the unit down if they disagree. The boards run different standard embedded operating systems and the software was written by two independent teams to minimize risk of the same failure mode in both boards.

Each board only does a little bit of work and the important units have backups. There are 4 units processing the sidestick input, 3 controlling elevator and ailerons, 3 controlling spoilers and elevator trim, IIRC 2 for yaw damper (FAC), 2 for each engine digital control, 1 for each display etc.

The requirements didn't really increase much since then. It is still desired that the tasks are split across many independent boards to minimize effects of one of them failing. So a CPU with few MHz clock rate and few MB of memory would still be able to do the job. But such slow chips are not manufactured anymore, so they are probably using whatever was most common chips few years ago.

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  • $\begingroup$ I'm not sure if I'd say that either the 80186 or the 68010 were particularly common in computers. Wikipedia: "Few personal computers used the 80186, with some notable exceptions" and "The 68010 was never as popular as the 68000". $\endgroup$ – a CVn Jun 17 '14 at 12:34
  • $\begingroup$ @MichaelKjörling: I suppose they picked it at the time because then performance did matter so they needed to take the faster chips that were not used as much. Since performance grew fast since then, modern designs can choose better tested chips over faster ones. $\endgroup$ – Jan Hudec Jun 17 '14 at 12:56
  • $\begingroup$ @MichaelKjörling: Still the point is that it was not special chips but general purpose ones that were already on the market. $\endgroup$ – Jan Hudec Jun 17 '14 at 13:50
  • $\begingroup$ Absolutely Jan, I'm not disputing the point you made (apologies if my comment came across as if it did), and the chip families were certainly common in computers at the time even though those particular models might not have been very widely used. $\endgroup$ – a CVn Jun 17 '14 at 16:27
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As Jan Hudec mentioned, advances in computing mean that off-the-shelf commercial processors offer plenty of computing power for use in UAVs or other aircraft.

Looking at a couple of examples:

The Rockwell Collins IPC-8303 computer uses an Intel Pentium-M 738 at 1.4 GHz, 2 MB L2 cache, 10 watts. There is also a PowerPC option.

The Rockwell Collins FMC-4000 mission computer is able to accommodate a variety of processors:

  • Quad core PPC 1.5 GHz
  • Dual core PPC 1.3 GHz
  • Single core PPC 7448 1.3 GHz
  • Single core PPC 8315E 600 MHz

They also mention that other components such as Intel Atoms or i7 Dual/Quad core processors can be added.

The amount of information processed by these computers has increased along with their power. The FMC-4000 can use a 10-gigabit uplink. Modern computers are designed to process all kinds of sensor data. For aircraft like the MQ-1 or especially the RQ-4, there are many sensors, including video data, feeding into these computers. They are capable of much more than the first flight computers.

Also mentioned by Jan Hudec, the key in aerospace systems is redundancy. Each subsystem is generally controlled by multiple computers. This ensures both accuracy and reliability, and prevents the whole system from going down due to one computer failing.

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