High Redundancy Actuation (HRA) is a novel type of fault tolerant actuator.
By comprising a relatively large number of actuation elements, faults in the
elements can be inherently accommodated without resulting in a failure of
the complete actuation system. By removing the possibility of faults
detection and reconfiguration, HRA can provide high reliability and
availability. The idea is motivated by the composition of human musculature.
Our musculature can sustain damage and still function, sometimes with
reduced performance, and even complete loss of a muscle group can be
accommodated through kinematics redundancy, e.g. the use of just one leg.
Electro-mechanical actuation is used as single element inside HRA. This
thesis is started with modelling and simulation of individual actuation
element and two basic structures to connect elements, in series and in
parallel. A relatively simple HRA is then modelled which engages a
two-by-two series-in-parallel configuration. Based on this HRA, position
feedback controllers are designed using both classical and optimal
algorithms under two control structures. All controllers are tested under both
healthy and faults injected situations. Finally, a hardware demonstrator is set
up based simulation studies. The demonstrator is controlled in real time
using an xPC Target system. Experimental results show that the HRA can
continuously work when one element fails, although performance
degradation can be expected.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.