Satellite Attitude Control – Inner/Outer Loop Architecture

Designed a satellite attitude controller using an inner–outer loop control architecture implemented in MATLAB, Simulink, and Simscape. The controller employs quaternion-based attitude representation, a proportional inner loop, and a lead–integral outer loop to achieve robust tracking and disturbance rejection.

Control Architecture

• Inner loop: proportional control for angular rate stabilization
• Outer loop: proportional + lead + integral compensation for attitude tracking
• Quaternion-based error formulation
• 0.01 s actuator delay modeled using 8th-order Padé approximation

Design Requirements

• Phase margin ≥ 60°
• Gain margin ≥ 6 dB
• Fast rise time with minimal overshoot
• Robust disturbance rejection

Validation

• Step, ramp, and sine attitude commands
• Step and sinusoidal disturbance torques
• Frequency-domain validation using Bode plots
• Time-domain validation using stepinfo metrics

Repo Structure

• matlab/ – controller design and analysis scripts
• simulink/ – nonlinear Simulink/Simscape model
• docs/ – detailed project report
• results/figures/ – plots and results

Tools & Skills

MATLAB • Simulink • Simscape • Control Systems • Spacecraft GNC • Quaternion Control