Helicopter control law based on sliding mode with model following

The design of a control law adapted to a process characterized by great parametric variations and strong couplings is considered here using variable structure methodology and approximate model following. It is shown that, even in the case of partial state availability, this approach leads to a much better robustness than modal control while allowing more versatility with respect to control objectives (a modification of the reference model does not imply a modification of the switching surface); furthermore these increased performances do not require a higher level of control activity than in modal-based schemes. After a brief recall of the methodology used, the paper is mostly concerned with a specific application; numerous simulation results are given.