Main architecture

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Please note that some parts of this page might be outdated or incomplete.

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1. Boards

• Sparkfun ESP32 Thing (main MCU)
• Pololu A-Star Micro 32u4 (motors, ultrasonic & speed sensors)
• Pololu A-Star Micro 328PB (GPS, LCD, ultrasonic sensors)
• Raspberry Pi 3B (openCV, Blynk server, GPS webapp)

2. Sensors

• 4x ultrasonic sensors
  • front center
  • front left
  • front right
  • left center
  • right center
  • back center

3. Comms

• Raspberry Pi <=> HW UART <=> ESP32
• 328PB <=> I2C <=> 32u4 <=> HW UART <=> ESP32
• ESP32 <=> BT/WiFi <=> Phone (emulated serial)
• ESP32 <=> BT <=> PS4 Controller
• ESP32 <=> ESP-NOW <=> Joystick (To-Do)

4. Peripherals

• ESP32:
  • IMU
  • All comms
• A-Star:
  • ESC & servo
  • Ultrasonic
  • Encoder
• 328PB:
  • GPS
  • LCD (I2C)
  • Buzzer & LEDs
  • Voltage sensor

5. Power

• Motors: included NiMH pack
• 2p li-ion
• TP4056 charger
• 5v regulator
• TP4056 USB connected to powerbank

6. Circuit board

• USB connectors on left side bottom
• Batteries connected via screw terminals
• 5V regulator output on power rail
• All gpio pins broken out (only for pcb)
• Connectors for all modules

7. Safety

• Batteries
  • ESC has auto poweroff
  • 5V regulator has auto poweroff
  • Must implement poweroff for Pi
  • Perform shutdown functions on low voltage
• Obstacles
  • if any distance changes by at least 2 cm since last read
    • if distF >= 60 and (distFL and distFR >= 60) and (distL & distR >= 40)
      • go straight forward
    • else if distF < 60 and (distFL or distFR < 60) or (distL or distR < 40)
      • if distFL > distFR and distL > distR
        • if going forward steer left
        • if going in reverse steer right
      • else if distFL < distFR and distL < distR
        • if going forward steer right
        • if going in reverse steer left
      • else
        • distLFL = 5 * distL + 4 * distFL
        • distRFR = 5 * distR + 4 * distFR
        • if distLFL > distRFR
          • if going forward steer left
          • if going in reverse steer right
        • else if distLFL < distRFR
          • if going forward steer left
          • if going in reverse steer right
    • else if (distFL or distFR <= 40) and (distL or distR <= 25)
      • same as above
    • else if (distFL or distFR <= 10) or (distL or distR <= 5)
      • brake and wait for 200 ms
      • read all sensors again
      • if any value is not the same
        • wait 100 ms
        • read all sensors again
        • calculate average of each distance
        • if mdoe is full auto go straight in reverse

  • else keep previous direction

  • add capacitive coating to chassis, connect to touch pin (To-Do)
  • if touch pin goes on stop immediately

  • wait for three seconds after detecting touch

  • if all distance sensors read less than 30 cm stop immediately (To-Do)
    • if clear after three seconds proceed normally
    • else try to rotate in 60* steps
• Connection
  • on connection lost for more than 100 ms brake
  • on any powerloss fully stop
  • on connect do not start until brake is toggled (To-Do)
  • if connection lost multiple times in less than two minutes fully stop (To-Do)
  • if more than two consecutive packets are lost stop (To-Do)

8. Chassis

• design
  • simple way to detach from wheelbase
  • easy access to everything
  • modularity
  • cable hooks??? (To-Do)
  • holes for cables (To-Do)