In industry, to ensure safety and reliability, critical actuators are designed with safety margins and are duplicated. In the event of a fault, a redundant actuator takes over. However, redundancy has drawbacks: it is expensive, it increases mass, resource consumption, energy consumption, and decreases autonomy. These constraints are significant for aerospace applications.
The current paradigm of actuator design (centralized action, monobloc, oversizing, complex servo control) does not allow breaking the limits of damage resilience. In contrast, biological actuators (e.g., skeletal muscle in animals, pulvinus in plants) have a decentralized architecture with multiple force paths, that makes them less sensitive to damage. This is the inspiration for our innovations with hierarchical actuators. Multi-degree-of-freedom actuators can adapt to micro-scale damage by distributing the load across neighboring actuators.
On a helicopter, for example, if the flight control actuator (blade orientation) begins to deteriorate with slight performance losses, a warning can be sent to the pilot to land for repair without threatening the integrity of the aircraft.