Fighter aircraft pilots are subjected to high acceleration and high altitude conditions. A multi-bladder physiological protection system is proposed to minimize the adverse affects of these hostile environments. The multi-bladder system provides independent pressure control within each bladder for the investigation of various protection schemes, such as sequential inflation of the bladders, or synchronization of the suit pressure with the G profile. The main objective of this thesis is the development of a control strategy for the pressurization of the bladders within the proposed protection system.

The terms and definitions associated with physiological protection are discussed in this thesis, emphasizing the physiological effects of high G forces and high altitude environments. It is shown, using control theory techniques, why current systems fail to satisfy the requirements produced by the new generation of fighter aircraft. A new valve system is developed which satisfies the new requirements. The valve system comprises two main elements:​ a new valve (hardware) and the proposed control strategy (software). The new valve incorporates, a stepper motor which rotates the valve spool, connecting either the supply port or exhaust port (if rotated in the opposite direction) to the valve outlet. Thus the air flow in and out of a vessel is controlled by precise adjustments of the exposed area of the supply and exhaust ports.

The proposed control is based on a variable structure control strategy. In this thesis, this method was applied to a single rigid vessel model. Computer simulation was used to demonstrate the control strategy for a single bladder, and a set of experiments were performed to verify the simulated results and study the control of pressure within a single vessel. The simulations were based on a mathematical model which was derived for the multi-bladder system. A multi-stage control strategy was proposed and applied to a general multi-bladder system. Simulations of the control system indicate that the expected performance is achiev ed. During each stage of the research, Lyapunov's method is used to prove the asymptotic stability of the closed-loop control system with the proposed variable structure controller.