Versions Compared

Old Version 59

changes.mady.by.user Anthony Luo

Saved on

compared with

New Version Current

changes.mady.by.user Olivia Markham

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Competition Year

2022-2023 Aerial Evolution of Canada Student Competition

Team

Waterloo Aerial Robotics Group

Architect(s)

Anthony Luo

Status

Status
colourGreen
titleV2.0
- Final competition hardware list

Last date updated

15 Feb - ZP-CV communication and CV search referenceAirside Power Architecture with Specific Rails and Limits

On this page

Table of Contents
minLevel1
maxLevel5

...

[Competition Requirements] [CR]Competition Requirements

[VN-300] [VectorNav VN-300] 2023-03-26 - VN-300 Rugged Harness

📐 Architecture

...

The architecture of a drone can be found in the [Competition Design Outline]. <# iterations> iterations of the drone will be created, at <#milestones>. <# final copies> of the drone will be created in “competition spec”. Our system will meet the requirements in [Competition Requirements].

...

Panel
panelIconIdatlassian-warning
panelIcon:warning:
bgColor#FFF0B3

All components marked “Optional” will not be present for the 2022-May 2023 Competition happening in Alma, QC

  • Airframe (Wings, Fueselage, tail)

...

...

Optional

...

...

Lighting

Airside Hardware Layout

...

System Level Electrical Placement & Routing Guidelines/Information:

  • The frame should not be electrically connected (aka should be at floating potential)

    • Complies with: UL1740

    • This can be checked with a DMM (when the system is not powered)

    • This means that if a PCB we are using has electrically connected mounting holes we need to take proper steps to achieve isolation

      • Sometimes PCB mounting holes are electrically connected to a GND plane for thermal reasons so we should also approach thermals with caution on sensitive electronics

  • Conformal Coating can be used within reason

    • The pro of conformal coating is waterproofing and makes it harder to accidentally should with a screw driver

    • The con of conformal coating is it prevents heat from leaving a PCBA

      • So anything that is conformal coated should receive a thin layer at most

    • Another con is that it can be annoying to remove in the case of reworking a PCBA

    • For example it would be fine to conformal coat a flight controller that runs cool

    • However, for example an RF transmitter we would want to approach with more caution

      • We could place a large heatsink on the primary chip(s) using thermal paste

      • Then we could consider conformal coating the other portions of the board

  • Cables, especially longer cables, should be within sheaths when reasonable

    • This offers protection against abrasion during natural flight vibrations

    • Exception to this rule is shorter cables that are placed further from anything that could be abrasive, specifically cables purely within the avionic compartment of our aircraft

  • Avoid loops in cable runs if possible

  • Varying conductor types should be separated when reasonable

    • Generally we consider four different types of cables: Digital, Analog, Power, & Coax/Rf

      • Digital: Characterized by signals with fast edges

        • Definition of a fast edge in this context and some examples to be added by an EE

        • Generally transcieving in 0 and 1 states asynchronously or synchronously

        • I.E. a GPS module’s cable connection to our flight controller is digital

        • An IMU is an example of a particular digital device that is sensitive to external noise.

      • Analog: Characterized by signals with slow edges

        • Definition of a slow edge in this context and some examples to be added by an EE

        • Generally transcieving data in varying voltage states

          • Though some protocols we consider analog will also transmit some digital data as well

        • I.E. a hobby fpv analog video camera has an analog data output

        • An analog video feed out of an analog camera is an example of a particular digital device that is sensitive to external noise.

      • Power: Characterized by constant voltage varying current designed for power transmission

        • Generally the voltage is constant though higher frequency noise may be present

        • These conductors can have significant current pulses

        • I.E. a connection from a battery to an ESC

      • Coax/Rf: Characterized by oscillating signals across the spectrum (~20kHz to ~300Ghz) intended for wireless transmissions and notably contained within a coaxial cable

        • A coaxial cable, specifically for our applications utilizing an SMA or RP-SMA connector, is generally used to guide sensitive RF signals between transceivers & antennas.

          • It is also worth noting antenna placement is critical, this is noted below in more detail

          • SMA & RP-SMA connector info should be found in the corresponding connectors arch doc section.

        • Because coaxial cables offer strong noise immunity the routing constraints of these cables are looser than others

          • Coax cables are very good at eliminating outside noise

        • For further information see: Coaxial cable

    • Each of these type of conductors should be physically grouped together, however, each type should be separated

      • I.E. All power stuff near each other, all digital near each other, but power separated from digital

      • This grouping and separation is physical distance, though of course there are other factors

      • Within PCBAs these groups may be mixed, this is fine, we will assume the PCB designer has taken the proper care to avoid issues as necessary

  • RF Transceiver Care

    • An RF transmitter should not be turned on (given input power) without a proper antenna connected as this can permanently damage the transmitter

      • Possible violations of this policy should be reported in Discord and transmitters should be labelled as damage (notably degraded performance) may not be immediately evident. We don’t want to blame each other, stuff happens, we just want to note it for the future! If you do not feel comfortable stating this publicly feel free to DM a lead you’re comfortable speaking to who can relay the message without naming names.

    • Transmitters generally get warm

      • They require a lot of power and therefore require some cooling

      • They are sometimes designed to be mounted outside an airframe for ambient cooling of wind passing the frame. As we may not be doing this we need to approach this with caution.

      • Notes regarding conformal coating are above.

    • The lower the frequency the longer the distance we can get for the same output power generally

    • The higher the frequency means more bandwidth generally

  • Antenna mounting

    • GPS sensors in particular are to our 900 MHz and 1.3 GHz transceivers and should be mounted away from antennas operating at these frequency ranges

      • GPS frequencies are fixed frequencies are1100MHz and 1500MHz

      • Our transceivers will hop around frequencies around their range looking for available channels so they are capable of hopping close to GPS frequencies and causing issues

      • For context it’s worth noting a 900MHz and 1.3GHz transceiver are capable of stepping on each others frequencies as well

      • For further reference see Guide: 1.2GHz -1.3GHz FPV Video System - Oscar Liang & GNSS Frequencies and Signals

    • Radio waves do not like to change medium

      • Specifically they do not like to pass through materials of varying dielectric constant

        • Passing waves through some varying materials may be fine, but be careful!

        • At the frequencies WARG operates at (6 GHz and below) foam will not have a considerable impact on signal integrity

        • Rain will have a measurable impact on signal integrity

      • This means mounting antennas outside of cases/airframes and providing LOS when reasonable

    • Antenna polarity should be deliberate

...

  • (Antenna Mounting Continued)

    • Ground antenna should be mounted with as much distance away from the ground as possible

      • This is to reduce ground reflection and has a considerable effect on reliability of an RF link

    • Antenna spacing should be minded

      • Any device with diversity (multiple antenna inputs) should have it’s antennas mounted with some spacing between them. Always follow manufacturer guidance here.

        • IE our VN-300 has specific manufacturer recommendations regarding recommended spacings and clearances

      • Different devices should have their antennas spaced out

        • See notes about frequencies and channels above.

  • Some notes about lightning

    • This entire section can be ignored for WARG purposes on nice days and the odds of a lightning strike are relatively low so don’t worry too much about these guidelines

    • As long as the current from a lightning strike is allowed to pass through your structure relatively unimpeded it will not harm the system

      • Notably isolating important electronics from the structure is important for this, see above.

      • To ensure this is possible having a somewhat conductive frame helps

        • This is not possible for composite frames and thus more complex techniques can be employed

    • Lightning likes to, if possible, enter and exit through sharp points

      • Ensuring that the sharpest points on a region of the system are all not electrical elements (notably antennas) will ensure lightning passes where we want it to!

      • A side safety note is that people are also relatively sharp points sticking out of the ground, however, unlike structures, you aren’t replaceable.

        • Be sure in lightning prone weather that people are not the path of lowest impedance for a lightning strike! This can be done easily by ensuring taller, pointier, grounded structures are nearby humans.

    • For ground equipment (towers and stations) grounding rods can be used

      • Notably this may not be possible for ecological reasons as well as if our ground station is on pavement

      • Grounding rods should connect into the earth (with a pointed end) electrically to the sharpest point at the peak of the structure

        • Ideally, as mentioned above, the entire structure is conductive which makes this easier to achieve.

Layout Introduction

The plane will be comprised of 5 main sections: the fuselage, cabin, avionics compartment, wings, and tail. The avionics + passenger compartment will be part of the main fuselage, while the wings & tail will house more electronics. All mandatory airside compute & airside peripherals must be mounted.

...

Panel
panelIconId26a1
panelIcon:zap:
panelIconText⚡
bgColor#4C9AFF

Electrical to provide insight on where the antennas should be mounted to minimize RF interference with devices such as GPS sensors, and also to provide detailed information on coax cable extensions.

The RFD900x will use the stock dipole antennas (the long ones), which means that RF Noise generated by the RFD900 may be fairly close to the source. It is

...

recommended to use

...

coaxial cable extensions to mount the antennas at least 20cm away from each other. Recommendations to put one antenna along the edge of a wing, and to place the other antenna vertically along a vertical stabilizer or landing gear. Maintain one antenna perpendicular to horizon and one antenna parallel to horizon.

Panel
panelIconId1f525
panelIcon:fire:
panelIconText🔥
bgColor#998DD9

Mech to provide clarity on the actual mounting location of the VTX antenna.

...

  • Servos connect to I/O Output and follow AETR, L->R

    • 1/2/3/4 Aileron (LO/LI/RI/RO)

    • 5/6 Elevator (LE / RE)

    • 7/8 Rudder (LR / RR)

  • Motors connect to FMU 1-5

    • Mot X : FMU X

  • FMU 6/7 for Aux Lighting

  • FMU 8 for Video Mux

  • Telem 1 → OSD

  • Telem 2 → RFD900x

    • will need external Power

  • CAN1 → Hereflow

  • GPS1 → M9N

  • VN300 → GPS2 OR Telem 3

Power Architecture

Panel
panelIconId26a1
panelIcon:zap:
panelIconText⚡
bgColor#4C9AFF

Electrical to update with batteries && actual rails. Note that some devices (cameras & transmitters) may need cleaner / dedicated rails.

The drone will run a 12S power system.

  • VBatt Dirty (For ESC’s)

  • 12V Dirty (For Flight Controllers & Jetson)

  • 5V Dirty (for servos, LED’s, etc)

  • 5V Clean (for VTX, Sensors, etc).

...

Power Architecture

The drone will run a 12S power system. The specific sources and rails are listed below:

A detailed description of how each device is being powered and which connector type is outlined in the following document: Power Distribution Architecture.

Wiring

All of the wires for the sensors will be pre-run through the frame in dedicated channels, with connectors left exposed near the sensor compartments and the avionics compartment. This means that any time a sensor needs to be replaced, we do not need to re-wire the entire sensor. this also means that when we need to re-wire the flight computers, we can use the cables that are already connected to the interface connectors an simply plug in a few large connector banks to our dev interfaces. Running more cables through the channels should be supported, but all necessary cables should hopefully be routed during assembly (or when it is easiest).

...

There will be 2 major components to the video system, one is the video relay and the other is the video receive devices. The video relay handles the transition between low frequency (1.3GHz) analog video into 5.8 GHz analog video. This video relay system will exist on a unique video relay tower, which houses the 1.3ghz antenna (singularity 1280), the 1.3ghz VRX, as well as the 5.8 GHz VTX and the respective antenna. Note that the VRX outputs video in an RCA format, and this will need to be spliced to solder pads or 2.54mm pitch pins on the VTX. The singularity 1280 must also be mounted so that the null zone is vertical.

If the 5.8 VTX were to be the Rush Tank Race II, then the antenna would be a u.fl terminated rush cherry w/long stem. If the 5.8 VTX were to be an AKK TS832, then the antenna would be an SMA terminated rush cherry w/stem. EE to provide clarity on whether or not adapters are needed. Both VTX will take signal from the video receiver, and share common VBatt & GND where VBatt is a 3S voltage. This VTX will be paired with the VRX, and can either be mounted on a tripod or a tall PVC pipe. This VTX may also require some degree of active cooling, consider how a fan may be mounted.

User endpoint Video Devices

All remaining VRX devices operate at 5.8 GHz, this includes:

...

...