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[DPRG] Video of Drone Contolled by BeagleBOne Black Running APM Pilot Software

Subject: [DPRG] Video of Drone Contolled by BeagleBOne Black Running APM Pilot Software
From: Dennis Clark dlc at frii.com
Date: Fri Feb 6 11:38:30 CST 2015

Am I the only one that cringes when people call these quad and hex copters "drones?"  Can we move away from this media term with such heavy, negative military connotations?

My rant for the day,
Dennis Clark
While traveling

> On Feb 6, 2015, at 10:31 AM, ed at okerson.com wrote:
> You can download it here:
> http://software-dl.ti.com/codegen/non-esd/downloads/download.htm#PRU
> Ed Okerson
>> Dick,
>> Good find.  Haven't watched it yet, but this phrase caught my eye:
>> "There's a C compiler for the PRU."
>> Any details?
>> dpa
>>> On 02/04/2015 12:27 PM, Dick Swan wrote:
>>> This is interesting 48 minute video
>>> <https://www.youtube.com/watch?v=2Twl2mQAh6g> from the lead developer
>>> of APM Pilot. It was given at a LINUX conference. He was describing
>>> the successful results of running APM code on LINUX.
>>> Here's my comments on some topics in the talk indicating the
>>> approximate time in the video that it occurred.
>>> 4:38 Live demonstration of a drone / airplane controlled via LINUX
>>> port of APM Pilot on a BeagleBone Black (BBB). The drone was at an
>>> airfield some distance from the conference location and watched a
>>> video as it took off, flew to way points and autonomously landed.
>>> LINUX console was remotely running on the overhead screen along with a
>>> video (Skype call) of the plane.
>>> 6:38 Drone was compiling LINUX kernel at same time as flying. On the
>>> BBB the kernel compile takes 5-6 hours because of relatively "low
>>> powered" CPU) when dedicated to this task. The compile time increases
>>> when APM is also running to around 10 hours.
>>> 1,200 SPI transactions per second from IMU in this application (i.e.
>>> simultaneous  APM Pilot and Kernel compile). Elsewhere he mentions 4K
>>> SPI per second.
>>> Uses a BBB "Cape" (similar to a Arduino "Shield") to provide the
>>> navigation sensors. Several BBB Capes now exist that contain the
>>> appropriate navigation sensors (i.e GPS and IMU and barometer). For
>>> example, the successful NavIO Cape from Kickstarter; and recently
>>> announced NavIO+. Plus several more Capes from others. Most (all?)
>>> were introduced in the last year.
>>> 20:21 Uses inline waits for sending 20 byte SPI packets. Better
>>> (faster?) than DMA because DMA setup has too much overhead.
>>> 22:05 Why use "user space driver" instead of kernel drivers? Answer:
>>> Same driver source code used on LINUX as on Arduino APM! Same drivers
>>> run on different OSes! It wasn't explicit but it seemed the user space
>>> drivers were for SPI and I2C; it was unclear if the low level SPI/I2C
>>> hardware control was in kernel space.
>>> 24:00 Future will see many of the current I2C sensors (gyro, accel,
>>> compass, GPS) migrate to CAN Bus.
>>> 24:58 Describes how APM handles real-time critical threads -- they're
>>> described as LINUX "FIFO scheduled real time task" with pages locked,
>>> predefined stacks, etc for best performance. There's six critical
>>> tasks that run in APM.
>>> 27:15 Some problems with "jitter" on the long duration nominal 20
>>> millisecond loop.
>>> キ19 of 2M loops (i.e. a 11 hour run) were over 30 msec. This was the
>>> same run APM with LINUX kernel compile in background. 18 of these were
>>> under 50 msec. Easily handled by APM Pilot since all the calculations
>>> running on the 20 msec loop adjust for the actual loop time rather
>>> than assuming it is "precisely" 20 msec.
>>> キLongest time was 1.7 seconds. This is a bug. Possibly writing to SD
>>> Card with interrupts disabled and waited too long.
>>> 31:20     Two things need microsecond timing; i.e. servo pulse input
>>> and PWM servo pulse output. Solution uses the 200 MHZ simple PRU
>>> (Programmable Real-time Units) on BBB. PRUs have direct access to GPIO
>>> pins. I think PRUs are on-board the CPU chip. PRUs have shared access
>>> to the BBB memory. There's a C compiler for the PRU. Total source code
>>> for the PRUs is 300 lines.
>>> 37:00 Description of latest Outback challenge competition held Oct
>>> 2014. It's a "search and rescue" autonomous drone looking for a human
>>> (via image recognition) at an approximate GPS location 6 miles away.
>>> Drone needs to fily to approximate location, search for the human and
>>> then drops a water bottle to the human. APM team won the competition.
>>> Many of the other entrants used chunks of APM code.
>>> 38:30 Picture of image recognition from Outback challenge. It looks
>>> similar to the images you see from a CMU Cam where color blob is
>>> highlighted with a rectangle overlaid on the camera image. I'm amazed
>>> at how the image recognition found a human shape from the air.
>>> Some of the new sensors drivers in development for integration with
>>> APM include.
>>> キOptical flow sensors
>>> キLaser range finding. Pointing downward for containing altitude.
>>> キUse Android quad-core (i.e. lots more CPU cycles) and then do image
>>> recognition using increased processing power.
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