Development of Robust Adaptive Nonlinear Control Schemes and Testbed for Hydraulically Actuated Turreted Weapon Systems

The objective of this Phase I effort is to show the feasibility of significanyly improving the pointing accuracy and the probability of hit of current hydraulically actuated weapon systems such as the M1A1 tanks and the Apache helicopters. To achieve this objective, robust nonlinear adaptive control schemes are proposed so that hard nonlinearities such as nonlinear dynamics of the hydraulic servo-valves and actuator Systems, the actuator and load friction and stiction and backlash in the connection and drive mechanisms can be accounted for and reduced by feedback. During the Phase I efforts, the nonlinearities will be modeled and simulation studies will be carried out. Furthermore, recently developed algorithms by the investigators will be applied to account for the nonlinearities of the hydraulic actuation and control system dynamics and compensate for the other nonlinearities such as backlash and variable friction due to aging of parts and changes in the geometric configuration. It is long understood that these nonlinearities in the drive mechanism of turreted weapon systems and in most high accuracy industrial machinery are the major causes of their performance degradation Among the approaches to handle these problems is the employment of direct drives, addition of new actuators with smart materials, use of magnetic and hydrostatic bearings. Another approach is a better modeling and the use of more advanced control methodologies. Due to recent advances in robust adaptive nonlinear control designs, we propose here to study the latter approach to reduce the effects of the aforementioned nonlinearities on the performance of systems actuated by electro-hydraulic drives. A testbed will also be designed for evaluation purposes. The advocated robust adaptive nonlinear control schemes are directly applicable to most high performance commercial machinery such as high speed and high accuracy positioning machines and devices, testing and quality control machinery, and other high performance manufacturing machinery that use electro-hydraulic systems in their drive mechanisms.