2021-09-03 Meeting Minutes - Drivetrain

Owned by
Emily Adam
Last updated: Sept 07, 2021 by
Ethan Cronier

Goals

  • Review drivetrain timeline for the term
  • Gauge each member's commitment for this term, make adjustments as needed
  • Delegate current list of tasks for the prototype


Current State of Progress & Action Items

Prototype

  • Mechanical assembly
    • Frame and chassis fully assembled. Wheels corrected (will reliably move with the motors now)
    • Differential bar attached, with the eye joint linkages at roughly the correct lengths
    • To do still:
      • Print and add bolt spacers on the differential bar linkages
      • Reattach the bottom, differential mounting gusset to the chassis with its spacers
      • Cut and add wheel treads
      • Print battery and weight holders, add to bottom layer of chassis
    • Learnings so far:
      • Experienced failure at the motor to the wheel shaft connection. Connected the shafts by a set screw in a coupler, without any modification to either shaft. The set screws were not able to grip onto either shaft in this state and ended up slipping. The solution: pair each shaft with a key that fits into the coupler. The set screw digs into the flat surface of the key
      • Should definitely press-fit bushings/bearings. Contributes to wiggle in the joints (i.e. at the bogie joint), and for bushings especially, ends up spinning in the plate
      • Design and manufacture with adjustability – will save time in the future
  • Wiring
    • Bulk of the connections completed
    • To do still (by Sahil/Lance, who offered to help):
      • Validate that the raspberry pi will be functional?
      • Add 12 AWG ground wire from the PDB. Connect to the stack of ground connections from a mating battery cable and the PDP
      • Connect the positive wire of the mating mattery cable to the circuit breaker
      • Wire up the current sensors to the ADC and rpi
      • Wire up the motors to the Cytrons
      • Mount electronics board to the chassis via hinges
  • Controls
    • Basically, starting from scratch (as per Sahil's request)
    • To do:
      • Driving RC code → Covered by Sahil
      • Wireless communication from PC to rpi
      • Collecting current sensor outputs

Update & Action Items

MemberHours per Week willing to DedicateUpdateAction Items
Emily (Differential bar)20
  • Prototype manufacturing, mechanical and electrical assembly
  • Wireless comms and current sensor code
  • Quickly make bolt spacers for differential
  • Ask about chassis requirements/timeline
  • Figure out budget
Asha (Wheel connections)5-10
  • Prototype manufacturing, mechanical and electrical assembly
  • Learn FEA!
Andrew (Chassis)10-15
  • Communicating about gimbal integration
  • Skeleton CAD for the chassis
  • Send photos of current skeleton CAD of chassis
Karan (Stress calculations)TBD, potentially 5-10
  • Communicating with Michigan about their approach to selecting their member diameter and thickness
    • Recommend physical tests and FEA → go with FEA
  • Learn FEA!
Max (Frame/structure)5-10
  • Prototype manufacturing, mechanical and electrical assembly
  • Finish up mechanical assembly (finishing up differential bar mounting, mounting electronics board on hinges)
  • Update battery holder

General Notes