Using a series of moving coils as a high redundancy actuator

This paper investigates the use of two electromagnetic actuation elements in series to produce a fault-tolerant actuator assembly. Faults in one or the other element are considered, and their influence on the behaviour of the whole system is analysed. By carefully choosing the mechanical parameters, it is possible to completely avoid any effect of these faults on the input/output behaviour. That means either of the two actuation elements can keep the system operational and restore the nominal behaviour without any changes to the system.