2021-07-16 Architecture Meeting

MECH

CV system is asynchronous - could go as fast as we want
- would be better to have a slower speed, stabler flight
Autonomy level: identify targets on the ground and land appropriately, identify ground targets and move there - pick up and taxi is tele-op
Sensors: lidar
- Lidar - mount next to camera so it will move with sensor - $1000 so might go with a different one https://www.robotshop.com/ca/en/leddartech-vu-8-channel-lidar-module-99-3-fov-spi-interface.html#shopping-cart-estimate-box
- Camera - don’t need a goPro, drone cameras would need to be good resolution cameras
  - stick with one camera
  - Gimbal needs to mainly pitch
  - Could have 1 camera pointing forward and 1 on the gimbal pointing
  - Video streams should never be merged for CV
  - Just needs to looks forward and looks down, could be a taildragger
Cabin space
- Boards could be in the wings but we want to make them easily interchangeable
Easy electrical connections
- DB9 connectors are good
- PPM decodor? - same thing as over CAN
Fly for 30-40 min
Max 3kg airframe
Need lots of cabin space for electrical board

FIRMWARE

Mech
- How fast do we want to go?
  - 15 m/s or 54 km/h
  - Srinjay says that the CV system doesnt care what speed the plane is, in theory. If you go too fast, youll miss the target and need to fly back.
  - Dhruv says controlled slower flight
- How autonomous will this plane be?
  - Srinjay says be able to identify targets on the ground by itself and taxi to target
  - Dhruv says that everything but picking up and taxiing to take off will be auto
- Sensors? Locations for sensors?
  - Srinjay says camera and Lidar
  - Mount it next to the camera so that it can be moved with the camera. Leddartech vu 8 channel lidar module
  - https://www.robotshop.com/ca/en/leddartech-vu-8-channel-lidar-module-99-3-fov-spi-interface.html#shopping-cart-estimate-box 1k dollars apparently
  - Gordon: I'm worked with an array of these: https://www.sparkfun.com/products/15179
  - Lidar is used for distance calculation
  - Multiple cameras on gimbal
  - CV doesnt care about gimbal location as long as it can look forwards and downwards
- Is there a way to make electrical stuff easy to detach
  - Electrical says it should be okay if we find good connectors
  - Looking at anderson connectors

CV
- LIDAR
  - 1d lidar vs 2d lidar
  - CV will be getting just distance (1d)
  - CV would like to do 2d in the future
  - Binocular camera can be used instead
  - radar/infrared can be used instead as well
  - Lidar has good range
- SOC
  - CV wants the nicest one we can afford
  - Either Jetson Nano (~$100) or Jetson TX2 (~$1000)
  - Warg apparently has a Jetson Tx2 unless someone stole it
  - How to protect the precious jetson baby
    - Put it near the back?
    - Maybe buy more than 1
  - No need for CAN as its overkill
  - USB to communicate between autopilot and CV
  - Sahil: Use CAN to communicate between autopilot and motor controllers?
  - Srinjay is going to benchmark the CV system
  - Google coral is debian based full system
  - Lance in favor of jetson, so we’ll likely use a jetson nano
  - Ryan says if all computers are on the plane, itll be hard to debug. 2 raspberry pis, 2 wifi adapters, open.hd, cheaper than lightbridge, less jank
FW
- Keep working on zero pilot, to get it into a working state.
- Modifications
  - Modify state machines to include jetson data transfers
- Sensors and peripherals
  - Dhruv has a slide of everything that will be used
    - https://docs.google.com/presentation/d/1Ae2hyC1K9xeE1glR5RGBl4vbCpFbnrdRjTMqV6aflVg/edit?usp=sharing
  - Are we getting an IMU and GPS module from vector nav?
    - Question for lance
    - It does sensor fusion onboard, but you can get raw measurements from another model
    - Specs on http://vectornav.com
  - Performance of vector nav
    - Picpilot used Vector nav chip
    - Spi and uart interface
  - Telemetry
    - Xbees?
    - RC comms should be separate
    - Open.hd can handle both video and telemetry data
      - Pass via jetson to rpi because autopilot already sends telemetry data to jetson
      - Leaning towards open.hd
  - Why separate altimeter
    - Gps has built in altimeter
    - Dhruv says gps altimeter is unreliable compared to external
    - Gps altimeter has a slower update rate
    - Gps altimeter doesn't have as good accuracy
- Logging
  - Log data in sd card so that we can see whats going on
  - Data in txt file
- Flashing and debugging
  - Moving away from stlink and stride
  - Goal is to use OpenOCD via usb port to flash and provide 5v power
  - Goal is to use ftdi chip to do usb debugging and flashing
- USB vs CAN
  - Leaning towards USB
  - Send data in Pathmanager, before sensor fusion
  - Keep considering using stm32 to do comms
    - If any of the modules fails, comms will fail
- Chip requirements
  - Adequate memory
  - Ftdi for flash
    - Use bootloader on the stm instead to remove ftdi requirement if needed
  - Led for debugging
Electrical
- BMS
  - Will be its own board
  - Provides power to rest of board
- PDB
  - Distributes power to everything, including jetson
  - Telemetry data going to jetson and flight controller
- What is the desired carrying capacity? (How heavy can we be?)
  - 10 kg max weight for comp
  - 25 kg max weight for legal reasons
  - Better to have be heavier so that the weight doesn't change when you pick up stuff
  - 0.5-1lb is the load of the stuff we were picking up
  - Put batteries in the wing?
- What is the desired flight time?
  - 30-40 minutes
  - Max you can fly in comp
- What is the max range of the aircraft?
- What is our max altitude?
  - ~300ft aka 91m
- What thrust do we want? How fast should we be able to go?
  - Mech assuming 11-15 m/s when doing calculations
- SOC stuff
  - Offline, to be discussed with FW
- Can multiple boards be combined into one pcb
  - Its about divvying up the work
  - Best practice is to split up the modules
  - 2 extra boards compared to spike
  - Tradeoff with modularity is that it means plugging more shit in
  - Right now we arent modular at all, so changing anything means remaking zeropilot