Choice of interconnect

I have been looking at different ways of connecting the different tiers of the robot that facilitates the following characteristics:

  • Real-time
  • Fault tolerant
  • Embedded
  • Low-power
  • Broadcast friendly
  • Master-less (survives
  • Adaptive (survives topology changes)
  • Bus architecture (many nodes)
  • "Fast"

So far the most likely candidate seems to be CANbus.

I will investigate further.

Hybrid BLDC ESC & GX25 ECU

I have advanced my thinking about the power train. More specifically the details for the board that will handle generator stage has converged somewhat. This is the current idea:

  • Use Brushless DC (BLDC) motor as both starter and generator connected to Honda GX25 motor.
  • Build a simple DIY ESC circuit that when powered will rotate the BLDC shaft to start the GX25 (working as a starter motor).
  • Build a rectifier circuit that when engaged to BLDC will make it generate power for charging batteries and giving the robot an extra power boost in the hour of need.
  • Build an ECU circuit with inputs for tachometer, voltmeter, ammeter and outputs for throttle servo and mechanical relays that allows engaging/disengaging the ignition, ESC and rectifier circuits on demand.
GX25 BLDC generator

The basic API for the circuit should look something like this:

  • Low-level
    • Start engine
    • Stop engine
    • Set throttle
    • Set charging
  • High-level
    • Start generator only when battery is low and/or power drain is high
    • Adjust throttle to accommodate load
    • Detect, alert and manage overheating
    • Detect, alert and manage low-fuel
    • Manage motor warm-up under different ambient temperatures.

How this circuit will communicate with central command and what will happen when communication breaks down is still to be decided.