walkabout actuated transfemoral prosthesis
SERIES ELASTIC ACTUATIOn
The actuators for the knee and ankle joints employ spindle-drive series elastic actuators. While relatively slow compared to harmonic drive-brushless motor systems, these actuators have favorable properties in terms of cost and fidelity of force output.
Our control paradigm builds on the neuromuscular model of human walking developed by Professor Hartmut Geyer of CMU and Professor Hugh Herr of MIT. Hill-type muscles are controlled by networks of simulated neural reflexes, while finite state machines handle the swing-stance-swing transitions. The output of this model provides a desired torque for the series-elastic actuator controller.
Because the model has no pre-planned trajectory, the leg more robustly responds to disturbances during swing phase compared with strategies based on impedance control.