Mobrob

mobrob

A mobile robot

Features

• Obstacle detection and avoidance
• Room mapping (explore mode?)
• Manual control (throttle + steer)
  • For example, through browser-based GUI
• Automatic navigation (A to B) (after exploring space?)
  • Complete more complex tasks like fetch an item?
• Charging capability preferable (e.g. MCP73831)
  • https://www.youtube.com/watch?v=GRd9uTwg7r4&ab_channel=MicroTypeEngineering
  • https://www.youtube.com/watch?v=TyaW8ZKumno&ab_channel=PlumPot

Initial design

Datasheets for components are found in Datasheets folder.

• Processor & connectivity: ESP8266 | datasheet

  • These values are for ESP8266EX
  • WiFi: 802.11 b/g/n Wifi, 2.4-2.5 GHz
  • Peripherals: UART / SDIO / SPI / I2C / I2S / IR Remote Control / GPIO / PWM
  • Operating voltage 3.3V (3.0-3.6V)
  • Average operating current: 80 mA
  • Around 50 kB RAM (for user, when connected to a station)
  • Requires external SPI flash! Up to 16 MB flash can be supported
    • Suggested: 512 kB (without OTA), 1 MB (with OTA)
  • Single core, 80 MHz

• Dual H-bridge motor driver: L293D | datasheet

• Power management:

  • Battery: 11.1V Li-Po (6-12V), (3 x 3.7V cells)
    • Price: $20-40
  • Buck converter (12V->5V): LM2596 or other...
    • https://www.youtube.com/watch?v=C7-8nUU6e3E&t=2367s
  • LDO (5V->3.3V): LM7805
    • https://electronics.stackexchange.com/questions/420999/use-5v-linear-regulator-and-ldo-3-3v

• Motors & chassis: Dual motor tank chassis (3-7V)

  • https://www.aliexpress.com/item/4000115994387.html?spm=a2g0o.order_list.0.0.21ef1802jPbMxm
  • Has slot for 4xAA batteries, could be modified to fit the rechargable 3-cell Li-Po battery.
  • Size: 9.7cm x 18.5cm x 5cm (width x length x height )
  • Motors: 130 size generic, can be replaced if necessary
  • Price: $18.50

• Sensors (both for proximity and distance, and other):

  • IMU?
  • UT/IR?
  • Others?

Discussion

I am not sure if either ESP32 or ESP8266 come in QFP format (only in QFN, no-leads). I guess JLCPCB and others also assemble these devices so maybe this is not an issue.

ESP32

ESP32 would be considerably better than ESP8266. It has a lot more functionality and also has 8MB of onboard flash (ESP32-S3FN8, see ESP32-S3 datasheet, p.11).

• https://www.youtube.com/watch?v=WWIy6a0T7WM&ab_channel=PlumPot

• Decoupling caps (as close of the pins as possible)

• External crystal? (see Phil's lab)

• Note the antenna/RF part!

  • No traces (or any copper) beneath the antenna part!

• Careful with differential pairs

• https://en.wikipedia.org/wiki/ESP32#ESP32-S3:

  • ESP32-WROOM-32D: PCB trace antenna, 4 MiB flash (probably preferable)
  • ESP32-WROOM-32U: U.FL socket antenna, 4 MiB flash