Aug 2025 – Apr 2026 · UCF Senior Design capstone sponsored by the Florida Space Institute (Fall 2025 – Spring 2026)

Florida Space Institute: BLDC Motor Drive for NASA's RE-RASSOR Lunar Rover

Replaced the stepper-motor drivetrain of RE-RASSOR, a variant of NASA's RASSOR lunar excavation rover, with a brushless (BLDC) system: about 81% lighter, about 82% lower power per motor, and more torque.

Embedded Systems Software Engineer · Team: Noah Fourari, Alex Fowler, Nicholas Bernhoft, Gabriel Pullam, Kenneth Arias, Jake Weber

Source (BLControl)Design document (full report) · 146 pp.
lighter drivetrain
~81%
lighter drivetrain
less power per motor
~82%
less power per motor
output torque (vs 0.59 Nm)
0.65 Nm
output torque (vs 0.59 Nm)
watchdog safety cutoff
< 300 ms
watchdog safety cutoff

Highlights

  • Redesigned the rover's drive system around Gimbal 2208 BLDC motors with a custom 3D-printed 4:1 gearbox, cutting drivetrain mass from about 1,560 g to about 296 g (~81%)
  • Cut power draw from about 18 W to about 3.2 W per motor (~82%) while raising output torque to 0.65 Nm, versus the original stepper's 0.59 Nm
  • Developed and debugged the C/C++ control software, resolving UART serial communication and data-serialization issues between the Le Potato single-board computer (Raspberry Pi–compatible) and the Arduino Mega
  • Configured and tested the DRV8313 (SimpleFOC Mini) drivers and wrote diagnostic procedures and a troubleshooting manual for PWM generation, watchdog timers and SSH/TCP communication
  • Verified safety behavior: the watchdog disables PWM within 300 ms, the system tolerates brownouts down to 8.5 V, and speed droops only 11% under load (spec: < 15%)

Overview

RE-RASSOR (Research and Education Regolith Advanced Surface Systems Operation Robot) is a 3D-printed variant of NASA's RASSOR lunar excavation rover, used by the Florida Space Institute for research and education. Its original stepper-motor drivetrain was heavy and power-hungry. Our six-person UCF senior design team, sponsored by FSI with faculty mentors Mike Conroy and Christian Vincent, designed a new brushless (BLDC) motor control system to replace it.

My role

I was the team's embedded systems software engineer. I finalized the software integration for the BLDC system and kept the control stack working end to end:

  • debugged the C/C++ control code and fixed UART serial communication and data-serialization problems between the Le Potato server (a Raspberry Pi–compatible single-board computer) and the Arduino Mega motor controller;
  • configured and tested the DRV8313-based SimpleFOC Mini drivers;
  • wrote diagnostic procedures and a troubleshooting manual so faults in PWM generation, watchdog timers and SSH/TCP communication can be isolated quickly;
  • supported the team's iterative, Agile-style test phases that verified the motor-control logic before final delivery.

System design

  • Motors: four Gimbal 2208 90KV BLDC motors, about 39 g each, with Hall-effect sensors for position feedback.
  • Gearing: a custom 3D-printed 4:1 gearbox per wheel, which recovers torque from the small motors.
  • Drivers: SimpleFOC Mini boards (TI DRV8313), driven through SimpleFOC's 3-PWM driver class.
  • Control: an Arduino Mega 2560 runs the motor control loop and receives commands over UART from the networked Le Potato board, which the operator's controller app reaches over the network.
  • Safety: a watchdog that stops the motors if commands stop arriving, plus brownout tolerance.

Results

Original steppers New BLDC system
Drivetrain mass ~1,560 g ~296 g (~81% lighter)
Power per motor ~18 W ~3.2 W (~82% lower)
Output torque 0.59 Nm (holding) 0.65 Nm (geared)

The final system also passed safety and load testing: PWM is disabled within 300 ms when commands stop, it keeps running through brownouts down to 8.5 V, and speed droops 11% under load (the requirement was under 15%).

Gallery

The six-person team with the blue 3D-printed rover and controller software at the UCF senior design showcase
Senior design showcase: the RE-RASSOR rover with the new BLDC drive and the controller software

Tech

  • C
  • C++
  • Arduino
  • SimpleFOC
  • DRV8313
  • Le Potato SBC
  • UART
  • SSH/TCP
  • BLDC motor control
  • PWM