User:Yvest

Intro

I'm working on implementing a pprz UAV as a way of merging my interrest in hobby planes, embbeded electronics and programming. My location is Montreal Canada.

My current Air frame

I'm currently working on a Multiplex Minimag with the following equipement:

• RC-er warp4-5T Brushless motor
• Castle Creation Phoenix 35Amp brushless ESC
• polyquest 2100mha 3S lipo
• 4 Futaba 3114 servo
• Berg 4L receiver
• Maxstream Xbee pro with whip antenna
• fma IR sensor
• PPRZ tiny13 v1.1

Gound Equipement:

• Dell Laptop
• Xbee USB packaged modem w/9db rubber duck or 14db patch antenna
• Orbit pocket ladder charger

The state of my project

Currently everything is connected to each other and basic functionality has been showed. Final/permanent mounting of the RC receiver and IR sensor is to be completed. There is currently no payload in this airframe and none is planned. I will probably move to a twinstar II when I'm ready to install a video system.

Todo

• Replace the resistors on the IR sensor to fix the gain of the op-amps to have the right range for 3.3V operation
• Final mounting of RC receiver and antenna
• Final mounting of IR sensor
• Install hatch retaining device
• Calibration of IR sensor
• Calibration of RC signals
• Range testing
• Initial flight testing and triming
• Tuning of the control loops
• Tuning of the Navigation gain

Projects that I'm interrested on developing to contribute to the project

USB tunnel

Code that will turn your tiny into a virtual serial port (ala ftdi chip) for the configuation of the GPS. Basic functionality is working, but I have severe issue with overruns and I wasn't able to make it work with the bootloader.

Tracking antenna

My take on this is that we should use off the self hardware so that it's easier for most people to build and use. Using a Pan & Tilt head driven by RC servo such as those sold by Servo city should fit the bill. We could use a tiny controller to drive the servo.

I'm considering these sensors:

• GPS: to find the location of the antenna. We could either set the coordonate of the antenna manually before the flight for a fix antenna or use the GPS to have the possibility to install the antenna on a moving vehicule
• Dual axis accelerometers: To provide mesurement of the elevation of the antenna (tilt angle)
• Magnetometer: To provide the azimut of the antenna

Barometric Altimeter

Altitude estimation thru GPS isn't very stable or precise. Because of this we could add a barometric altimeter to improve the altitude estimation. Current options are:

• VTI SCP1000: Direct digital reading thru a SPI interface. 17bit resolution provides as much as 9cm resolution. This sensor is very small. A breakout board is available from sparkfun.
• Freescale has a good range of analog absolute pressure sensor. We could either use an extra AD channel on the LPC or use an external ADC for better resolution.

Instructions

Modification of Berg4L for use with tiny

This is a very good receiver for many reasons, it's size/weight, range, filters are all good reasons to choose it. Here are the step you need to take to midify it for use with pprz:

1. remove the shrink wrap
2. Desolder the headers. We will not use them with tiny AP as the servos are connected directly to the AP. This is pretty easy to do when you have a hot air rework station. If you don't have one, your best bet is to cut the header off and remove the left over pins one by one with a regular iron. There is a piece of sheilding material that is connected to one of the ground pins of the header. You need to remove it carefully from the header without damaging it and re-solder it to the gnd pad.
3. You need to solder 3 wires to the receiver. Gnd, +5V and PPM. To locate the PPM signal, first locate the PIC micro controller close to the location of the headers. The PPM signal is on the corner pin closest to the corner of the receiver. Soldering a 28guage wire directly to the PIN isn't very difficult. For the power connection, use the pads that were used for the header. The outside pin is Gnd, the second pin is +5V. What I did is solder the wires on the pad going strait down, then I looped the 3 wires 360 degrees and glued them to the PCB with hot glue. This provides good strain relief.
4. While you have the PCB in your hands, take the opportunity to remove the crystal connector and solder your crystal directly to the PCB for added reliability.
5. I also used some hot glue to add more strain relief to the antenna
6. Use some large shrink wrap to cover the entire receiver again

Modification of FMA IR sensor

Comming soon

Enabling debuging of link for xbee

"export PAPARAZZI_DEBUG=x" before starting link. This will show the RSSI when using xbee transport (second number on the line that starts with getting XBee RX64: or getting XBee RX16:. Smaller is better)

Putting telemetry in Debug mode (To add PPM messages)

add ap.CFLAGS += -DTELEMETRY_MODE_FBW=1 in the aircraft. This will add the PPM messages to the list of messages send by the AP. (see the debug section of telemetry/default.xml)