Increasing reliability by means of efficient configurations for high redundancy actuators

A high redundancy actuator (HRA) is composed of a high number of actuation elements, increasing both the travel and the force above the capability of an individual element. This provides inherent fault tolerance: if one of the elements fails, the capabilities of the actuator may be reduced, but it does not become dysfunctional. This paper analyses the likelihood of reductions in capabilities. The actuator is considered as a multi-state system, and the approach for k-out-of-n:G systems can be extended to cover the case of the HRA. The result is a probability distribution that quantifies the capability of the HRA. By comparing the distribution for different configurations, it is possible to identify the optimal configuration of an HRA for a given situation.