Mechanical System Goals

• Provide hip and knee actuation for mobility assistance.
• Achieve ~35 Nm torque per leg via motor + geartrain.
• Keep the exoskeleton lightweight, modular, and comfortable (soft exoskeleton concept).
• Ensure quick donning/doffing for competition rules (fast removal = extra points).

Actuation System

• Motors: EaglePower 8308 (nominal torque ~2 Nm each).
• Gearbox: 20:1 cycloidal drive → ~40 Nm output torque.
  • With ~15% loss → effective torque ≈ 34 Nm.
• Back-drivable design: Cycloidal gears chosen for quasi-direct drive feel (low backlash, smooth torque transfer).
• Encoders: Mounted for both motor shaft and output stage → backlash detection + compensation.
• Hip actuators: Direct drive into hip joint.
• Knee actuators: Direct drive, but currently we are working on making them belt-driven from hip-mounted actuator (reduces distal weight).

Mounting & Attachment

• Primary Mount: Belt around torso → distributes weight of actuators, control boards, and battery.
• Limb Attachment: Ratcheting buckle belts (like snowboard boots) → quick-release for competition.
• Load Distribution:
  • Hips bear most actuator load.
  • Knees connected via belt drives → lightweight at lower limbs.
• Tensioning System: Adjustable to accommodate different body sizes and prevent slippage.