Future Autopilots

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Proposed additions

We're always looking for great ideas. If you'd like to see something added or changed on Tiny v2.11 list it here! Please keep your suggestions relevant to this revision and post other requests in the Hardware Wish List.

  • Separate GPS Option
see TWOG/v1.0
  • EMI filters on ADC channels
    On Semiconductor NUF4220MNT1G 4-line EMI Filter
Analog sensors are severely affected by video and modem RF. We typically see ADC reading fluctuations of +/-0.5% in a well shielded installation, but a misbehaving video transmitter or a noisy Radiotronix modem can affect ADC channels by more than 50% in the same well shielded installation. The addition of effective filters to the ADC inputs should greatly reduce the effects of RFI and allow for a much broader range of RF equipment and airframe configurations.
I suggest the On Semiconductor NUF4220MNT1G. A 2mm x 2mm chip that filters 4 analog signals, attenuatiing RF frequencies above 16 Mhz but particularly the 800 Mhz to 5 Ghz range. (Jeremy)
NUF4220MN is a 4 line LC EMI filter array designed for audio applications. It offers greater than -30 dB attenuation at frequencies from 800 MHz to 5.0 GHz, with no line loss. This part is a single chip solution for audio interface applications, 2 speaker lines with a microphone line. This device also offers ESD protection-clamping transients from static discharges and ESD protection is provided across all capacitors.
  • Decoupling capacitor on GPS antenna
    The u-blox reference design calls for a 47pF 10% 0603 capacitor in series between the receiver and antenna. I have no idea why this is useful but apparently it must be, because this technique is commonly seen on WiFi cards, video transmitters, modems, even R/C receivers. Maybe we're missing out on something great? (Jeremy)

This is typically used as a DC block capacitor. Many RF amplifier circuits either require DC on their output to be powered, or have stray DC on the output. Also, many antennas are shorted at DC. The capacitor serves as a high-pass filter that allows minimal loss at RF frequencies. It isn't necessary unless the manufacturer specifies it.(hpux735)

  • Filtering for GPS antenna
Make some sort of low pass or band pass filter to reject outside frequency's. This would be useful since most UAV's are not just used to fly but for video or other sorts of communication which tend to interfere with the GPS Signal. Maybe similar to some of these designs http://www.webx.dk/rc/video-wireless/filtergps.htm (Danstah)

Re: I have since found out that the lea-4p has a built in saw tooth filter. Adding a filter would probably only reduce the signal strength

  • VIRTUAL AUTOPILOT (The Next Logical Step)*

The virtual autopilot concept is based on virtualizing the autopilot through the Paparazzi GCS software and meant for larger aerial platforms. The avionics unit will be an actual micro pc running Linux such as http://www.fit-pc.com/web/ or the gumstick. The altimeter, gyro, servos, sensors, cameras, custom I/O , etc... are all modular. The telemetry/datalink is a remote desktop connection to the pc on the remoted vehicle (remote vehicle has a hardware in the loop type configuration).

The modular design saves autopilot hardware development costs. The modular design also saves repair costs. For example, currently if sensors and other components become infused with the autopilot board and the board or sensor goes bad repair costs raises. A modular design with a virtualized autopilot creates an environment for rapid development and integration of anxilary equipment (sensors etc...). Hecto's Paparazzi software suite is perfectly designed for virtualizing an autopilot because its meant for autopilot development (I must add its ahead of its time!).

Think of all the hardware you can run through usb ports alone and all the programs you can run simultaneously on a pc. With a remote desktop connection through a TM link, your UAV increases its functionality significantly. Akira Devereaux http://akiraproject.net/cv