This patent discloses a Parallel Variable Stiffness Actuator (PVSA) that combines a direct-drive motor with a variable stiffness spring arranged in parallel. The design allows the motor to apply force directly to a load while the spring’s stiffness is modulated independently. The disclosure also describes a resonant energy accumulation method in which spring stiffness is adjusted only when no energy is stored, and the motor applies force in resonance with oscillatory motion to maintain constant amplitude.
Why it matters: Traditional actuators are limited by bandwidth and efficiency trade-offs. This invention enables precise force control, efficient energy storage, and resonance-based energy amplification—all within a compact design. The approach has applications in robotics and wearable devices where adaptable, energy-efficient actuation is essential.