Astromech Droid Controller

The Astromech Droid Controller project involved the design, assembly, and integration of a custom controller for the Cal Poly Robotics Club's Astromech unit. My work focused on enclosure design, codebase integration, and PCB collaboration.

Project Overview

• Designed a robust main controller board integrating power, motor, and telemetry subsystems.
• Led the enclosure design process, ensuring functional, user-friendly housing and easy maintenance.
• Integrated legacy code for motor decoders and RC interface on ESP32 using C++.
• Collaborated on PCB schematic/layout decisions with attention to expansion capability.

PCB Design Highlights

• Custom ESP32-S3-based PCB designed in KiCad for minimal size and vibration resistance.
• Key features:
  • Onboard 3.3V/5V regulators, fuses, and bypass jumpers
  • All ESP32 pins exposed for future expansion
  • I2C, UART, PWM, ADC, IO expander, quadrature decoder, and screen/Dpad connectivity
  • Robust connectors, terminal blocks, and mounting holes
  • Strategic USB-C port alignment for accessible enclosure mounting
• 

Enclosure Design Process

• Designed iteratively in OnShape with regular client feedback
• Optimized internal fit for PCB, screen, connectors, and cable management
• Features:
  • Mounting pillars for RC receiver and PCB
  • Dedicated screen mount, cable management, and LED/connector accommodations
  • External tabs for integration into the robot chassis
• 

My contribution: I led the enclosure design, collaborating closely with our professor and iterating based on feedback to meet all functional and space requirements.

Software Overview

• Object-oriented, modular code in Arduino/C++, compatible with legacy Astromech systems
• SBUS protocol processing for RC input (16 channels, robust failsafes and lost-frame handling)
• Custom classes:
  • Motor_pwm_control: Converts SBUS values to PWM for motors, including acceleration smoothing and signal inversion
  • ServoControl: Smooth dome and servo behavior with failsafes
  • ScreenManager: Real-time display of system/channel status and error indications
• Source Code not available publicly due to project confidentiality.

Hardware Integration

• Rigorous connector specification, assembly, and testing (color-coded wiring, terminal blocks, electrical safety)
• Custom crimped screen connections for robustness
• PCB hardware inverter for SBUS UART compatibility
• 

Challenges & Solutions

• Motor driver fault tolerance: Current sensing and auto-shutdown protocols
• SBUS implementation: Memory optimization via Arduino partition tuning
• Legacy code integration: Adapted motor/RC logic to ESP32; addressed channel mapping and interrupts
• Mechanical fit: Iterative enclosure redesign for usability and cable routing as per feedback
• Failsafes: Immediate neutral/center response on signal loss to prevent erratic robot behavior

My Role

• Led enclosure CAD development and client interactions in OnShape
• Collaborated on PCB layout decisions (component placement, USB access, test fit)
• Integrated legacy C++ control logic and debugged channel/interrupt management on ESP
• Documented testing results, maintained GitHub project updates