Multi-variable control of a high redundancy actuator

The High Redundancy Actuator project deals with the construction of an actuator from many redundant actuation elements. Whilst this promises a high degree of fault tolerance, the high number of components also poses a unique challenge from a control perspective. This paper shows how the state space model of a stack of actuation elements in series can be separated into a high dimensional internal and a low dimensional external subspace. Once the internal states are decoupled and damped, the behaviour is dominated by the few states of the external subspace. This means that the high redundancy actuator with many redundant elements behaves just like a conventional single actuator.