Analysing the reliability of actuation elements in series and parallel configurations for high-redundancy actuation

A high-redundancy actuator (HRA) is an actuation system composed of a high number of actuation elements, increasing both travel and force above the capability of an individual element. This approach provides inherent fault tolerance: if one of the elements fails, the capabilities of the whole actuator may be reduced, but it retains core functionality. Many different configurations are possible, with different implications for the actuator capability and reliability. This article analyses the reliability of the HRA based on the likelihood of an unacceptable reduction in capability. The analysis of the HRA is a highly structured problem, but it does not fit into known reliability categories (such as the k-out-of-n system), and a fault-tree analysis becomes prohibitively large. Instead, a multi-state systems approach is pursued here, which provides an easy, concise and efficient reliability analysis of the HRA. The resulting probability distribution can be used to find the optimal configuration of an HRA for a given set of requirements

Switching fault tolerant control design via global dissipativity

This article addresses the issue of fault tolerant control (FTC) from energy point of view for general impulsive systems with faults ranging over a finite cover. The dissipativity theory is introduced into the design of fault detection and a unique scheme that simultaneously performs fault isolation and FTC. The proposed framework relies on a simple dissipativity-based switching among a family of pre-computed candidate controllers without any additional model or filter. The states are ensured to be bounded during the switching delay. A RLC circuit example illustrates the efficiency of the proposed method