Tuesday, April 30, 2013

LemonRX Failsafe Notes

fmak2 clarified how the Lemon-RX failsafe works.

For Lemon Rx 8 channels receiver, failsafe is available for all channels and some user may found it useful (for robotics application or UAV). 
When bind plug is still plugged after successful binding, pressing the mem. button will cause the receiver to memorize all channels settings at the time the button is pressed for use in failsafe. If the failsafe is enabled correctly, green light should be on at the bottom of receiver. Press mem. button again while bind plug is plugged will cause the green light to turn off. This indicate the failsafe mode is disabled. Take the bind plug out before flying!
Even in the event of power disconnected, failsafe settings are still saved and will restore to its functions accordingly when power is provided. 
About failsafe enabled:
When the primary receiver and satellite receiver is unable to detect any RF signal for continuous time interval of approximately 3 seconds, all channels will be restored to the saved setting. At this point the receiver will try to find valid RF signal. If valid signal is detected, the receiver will use the valid signal immediately. 
About failsafe disabled:
When signal is lost for continuous time interval of approximately 3 seconds, all channels will have no output (all outputs are pulled to ground).
If you don't like failsafe, make sure green light is not on before flying!
And a note on CPPM/PPM and UART:

We aware that most people use CPPM/PPM for Adurino application, which is mostly used in quad-flyer or robotics. 
We had actually implemented CPPM/PPM sum output for 8 channels receiver. However CPPM/PPM sum is just too rough and troublesome for quad or drone application (including resolutions / number of channels/easy of implementation/ delays..etc.).  
It maybe better to switch to HUART which is currently available for 8 channels in the long run (high speed UART, 115200bps, 8N1). Use Adurino to read the HUART data directly. If you can check out our website, we have already simplify as much as we can for easy integration for Adurino or other embedded system application.

Sunday, April 28, 2013

Drone vs. Drone!

Andreas and I went flying this morning, and were seeing how close-in we could navigate.  Turns out closer than we thought!  Amazingly, total damage was one prop tip sliced cleanly off.

Monday, April 15, 2013

Vendor: APC Props

Direct from the manufacturer in lovely Woodland, CA... they build em, they sell em! As you'll probably guess, they're prop builders and not web page designers.

(toc: Vendors)

California Style Ultrabatics

Two beautiful slope soarers kicking it back Cali Style.  Buzz and the SwissFish. Beautiful and looks like so much fun!

Vimeo video here.

Sunday, April 14, 2013

Micro-H Quad

sparrow1717 shares his design in this RCG thread and provides these notes:

  • 10mm SlowStick aluminum fuse for arms
  • 5in props
  • 12 amp escs
  • 2900 kv motors
  • 2S 1000 mah batt
  • 240 mm span
  • 170mm motor to motor
  • 7oz AUW

"I went with the H layout for ease of build and extra surface area for carrying cams or whatever. Try to build as light as you can. Weighing in at 7 ounces my quad flies quite spirited on 2S.  As far as the frame spacing . I decided something close to 250mm diag spacing as this seems to be a popular size for 5 in props. I finalized at 170 mm from motor to motor.

Open Source Stabilization Software for OrangeRX RX3S

Another interesting Open Source project, this one for the RX3S OrangeRX 3-Axis Flight Stabilizer. JohnRB summarizes the improvements:

  • Optimized interrupt handlers to minimize servo jitter.
  • The Aux input is no longer just on/off. It controls the gain for the stabilization correction from 0% (full off) to 100% (full on) and anything in between.
  • The reverse switches are no longer needed to reverse the correction. Thus they are available for other functions.
  • The gain controls function differently. The 12 o'clock position is 0 gain, counter clockwise from 12 o'clock adds correction in one direction, clockwise from 12 o'clock adds correction in the opposite direction. Thus no longer a need for reverse switches.
  • Adds Attitude Hold to allow the current attitude to be maintained.

This might be a useful starting point for someone who needs a prepackaged Arduino-based unit with 3 gyros as well.

Saturday, April 13, 2013

Power Off Dive Testing

Here's a nice diagram from RCG that shows how check your CG by testing how the plane recovers from a dive.

Friday, April 12, 2013

SF Drones Startup Meeting Notes

Eric Cheng has some nice photos and notes of the first SF Drones meeting.   Follow the link and check it out!

New Phantom Blade Guards

Snapped from a video interview with DJI CEO Colin Guinn at NAB 2013.  Most of the talk was about their new brushless gimbal, but what caught my eye was the blade guard on one of their upcoming models.  I might try making something like this for the Arcticopter!

Here's the full video:

Wednesday, April 10, 2013

Module for Ladybird and other Walkera Units

The Walkera RC Magic Cube MTC-01 V2.  Can be plugged into trainer port, and also has an iphone android app.  On sale at Hobby One.  Review and binding instructions here.  Notes on the app here.

Update: Here's a note from RCG:
 You can use the mtc-01 on your 9x and I have flown my ladybird using it with stock 9x firmware. but you have to reverse some channels. I recommend you upgrade the stock 9x firmware to er9x, because on the stock 9x firmware the elev and aile channel is swapped and there is no way you can change it with stock firmware. With er9x you can easily change it.

Saturday, April 6, 2013

MAVLink Protocol Notes: Packet Decoding

Here's how to decode a MAVLink Packet.  Some sample code here, and a video of the multicast demo here.

Example Packet (Heartbeat)
packet length = 17 (6 bytes header + 9 bytes payload + 2 bytes checksum)

hdr len seq sys cmp id   payload (len 9)------------------  crc---
 0   1   2   3   4   5   6   7   8   9   a   b   c   d   e   f  10
FE  09  4E  01  01  00  00  00  00  00  02  03  51  04  03  1C  7F

Fixed Header (6 octets)
0. packet header, always 0xFE
1. message length (9)
2. sequence number -- rolls around from 255 to 0 (0x4e, previous was 0x4d)
3. source system - what system is sending this message (1)
4. source component - what component of the system is sending the message (1)
5. message ID (0 = heartbeat)

Variable Sized Payload (specified in octet 1, range 0..255)
06-0e. payload

Packet Checksum
0f-10. CRC25

In common use (single aircraft, single autopilot), source component and systems will be (1,1)