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Methods for analysing the robustness of linear systems to parametric uncertainty are relatively well developed. However, the converse is true for nonlinear systems. The recently developed velocity-based framework provides a degree of continuity with linear methods which has the potential to allow established linear methods to be applied when analysing the robustness of nonlinear systems to uncertainty. This paper reports initial investigations in this area with particular reference to the guided weapons application area.

We establish that for SISO systems lack of well-defined relative degree is not an obstacle to exact inversion. Sufficient conditions for the existence of exact linearising inputs are derived. Exact tracking solutions of a number of example systems, including the ball and beam system studied by Hauser et al. (1992), are analysed. It is shown that linearising inputs may be: 1) highly non-unique, 2) discontinuous and include impulses, and 3) fragile. A framework is established for approximate linearisation. whereby exact linearising inputs are formulated as the limits of sequences of realisable, arbitrarily accurate linearising inputs. This framework is constructive in nature and of key importance when the exact linearising inputs are, for example, unrealisable.

This paper presents a robust adaptive fuzzy neural controller suitable for motion control of a multi-link robot manipulator. The proposed controller has the following salient features: (1) the dynamic fuzzy neural networks structure, i.e. fuzzy control rules, can be generated or deleted automatically; (2) adaptive learning; (3) online learning of the robot dynamics; (4) fast learning speed; and (5) fast convergence of tracking error. The global stability of the system is established using the Lyapunov approach. Computer simulation studies of a two-link robot manipulator demonstrate that an excellent tracking performance can be achieved under external disturbances.

Investigates the extension of the gain-scheduling approach to flight control tasks where the conditions required by conventional techniques need not be satisfied. In particular, situations are considered where the vehicle, is manoeuvring aggressively far from equilibrium, the airspeed need not be slowly varying and/or scheduling on the instantaneous incidence angle is required.