I know, the world probably has enough flying machine projects, but here is yet another one. AutoQuad's original design goal was high precision autonomous flight. It took five prototypes before I was happy with the hardware. The current prototype, AQv5, is showing very promising results. In fact, there is little left to do before this first goal can be checked off the list. Using this as a solid base, I intend to continue research, design and experimentation toward vision based navigation for indoor and outdoor use.
Hardware:
- 2" x 2" board with same mounting pattern as the MK FC
- Input voltage ~7.5v => 18v
- High efficiency DC/DC converters
- STM32F103 32bit Cortex M3 microcontroller @72 MHZ
- standard ARM 20 pin JTAG header for real-time debugging
- up to 8 PWM ESC motor control (prefer Turnigy ESC's with custom firmware)
- 2 powered payload servo controllers
- optional ultra sonic range finder
- Spektrum satellite (remote receiver) 2.4Ghz RC radio
- uSD card slot
- optional onboard uBlox LEA-XX module w/battery backup & timepulse capture
- optional female SMA connector for active GPS antenna
- optional external GPS via standard 6 pin connector (EM406, EM401, uBlox, MTK)
- optional onboard xBee module - up to 300mA (2.4Ghz, 900Mhz, bluetooth, etc.)
- optional external radio via standard 6 pin FTDI connector - up to 1A
- I2C bus connector for I2C ESC's
- modular sensor board (SBv5) - 100% analog sensors, EMI hardening:
+ 3 axis acc (ADXL335)
+ 3 axis mag (HMC6042 & HMC1041Z)
+ 3 axis gyro (IDG500 & ISZ500)
+ 2 temperature sensors
+ pressure sensor (MPXH6101A)
+ battery voltage
Software:
- Fully threaded RTOS design written in C - 60% idle
- All sensors read at 113KHz (~1.4M sps total)
- 450Hz motor update rate
- 200Hz attitude, 3D velocity / position solutions
- Full downlink telemetry
- Detailed system state dumps @200Hz => uSD card w/FAT32 FS
- Quaternion based attitude filter additionally producing rotation matrix and Euler angle outputs
- All math in single precision floating point
- Temperature compensated and calibrated sensor suite
- Custom ground station software w/bi-directional command and control API
- Cascading PID control system, velocity based for smooth transitions
- Auto land / takeoff
- Hover position / altitude hold
- Autonomous waypoint mission navigation
- Precise altitude hold indoors
Example of current capabilities:
Design philosophy:
- High performance
- Efficiency
- Ease of development
- Consistency / Repeatability
- Low cost
There is always room for improvement. For instance, I would like to see how much of a benefit using a SPKF (Sigma Point Kalman Filter) would be over my fixed gain navigation filter. Looking forward to the new Cortex M4 uC's with a hardware FPU so that any such math intensive solution can be more easily handled. As I mentioned above, there is a lot of room for work with vision navigation and SLAM. Also interested in propulsion efficiencies which with an eye toward higher endurance. Although the PID based control system works extremely well, I'm interested in exploring different types of MPC (model predictive control) to reduce control costs and increase precision.
I'm wondering if there is anyone interested in joining forces to work on some of the above mentioned or anything else along these lines that presents itself. This is only a hobby for me and I currently have no profit motive. This is definitely not a beginner's project as you can see by my sloppy SMD hand soldering job.
Comments?
Comments
Flemming/Ruben: The Recom converters were used for efficiency which translates into less power and a lot less heat. Note that they are pin compatible with regular LDO regulators and can be changed.
There are a lot of "extra" parts on this board as it is an experimental prototype. Quite a few things can be replaced or even omitted with little or no impact on operational use. It's entirely up to the user.
Robero: You are right, the radio close to the board can cause a lot of trouble. But I have overcome these problems with design considerations. Notice the sensor board is ringed by via's and there are no external traces - all of the analog wiring is in internal layers, effectively in a Faraday cage. The radio and other noisy parts are running on their own DC/DC converter, each with it's own LDO regulator. All analog power supplies are headed up with inductors and a large RC filter. The OPAMP's are LVM834's which are EMI hardened.
Before these changes were made, the sensor signals were unusable, but now I cannot detect any difference with or without the radio mounted and powered. For long range use, you would probably want to use an external high powered radio anyway.
Whoops! This blog was not ready for publish - I may have hit the wrong key last night :)
I've updated with a demo video.
Nice job Bill, what stm toolchain are you using?
The ground planes have two purposes:
* As a solid plane of ground to allow low-impedance ground connections all over the board and provide better noise immunity and reduce noise emissions.
* By filling as much as possible with copper, so the empty spaces are about the same size you make it easier to produce the board without getting under-etching, so you get a higher yield and the PCB manufacturer will hate you less.
I'm also wondering why the integrated DC/DC converters were used in stead of a much cheaper MC34063 based solution.
... but yes, provided it's Open Source, so I can use it, then it's a very nice board.
Hi Bill,
this is an a good design but i have some doubt about your idea to put a Xbeeproo near micro and gps . is not a good approach in ,my test the RF disturb micro and sensor a lot . Are you yet tested the power line ... i see that you use 2 DC DC converter how many layers in your board ? Your shape cannot be use in some application is good for quad but not for fixed wing or hely.
I think that is possible to test it in flight because use same micro of Ardupilot32
Regards
Roberto
- Why a 6.5V DC/DC converter, and not 3.3V one?
- (Offtopic) Why is everyone always filling the unused parts of the board with copper?
- Any videos of it flying?
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