Experimental study of command governor adaptive control for unmanned underwater vehicles
Makavita, CD and Jayasinghe, SG and Nguyen, HD and Ranmuthugala, SD, Experimental study of command governor adaptive control for unmanned underwater vehicles, I E E E Transactions on Control Systems Technology pp. 1-14. ISSN 1063-6536 (In Press) [Refereed Article]
The control of unmanned underwater vehicles (UUV) is a complex problem mainly due to the nonlinear dynamics, uncertainty in model parameters, and external disturbances. Adaptive control is a promising solution to address these issues. Nevertheless, its full potential is yet to be realized, especially in underwater vehicle applications, mainly due to the compromise between the transient performance and a smooth control signal. The addition of a new command governor with standard model reference adaptive control (MRAC) named as a command governor adaptive control (CGAC) has been proposed as a promising solution to this trade-off. Nevertheless, the suitability of CGAC in underwater vehicle applications and its performance are yet to be verified. This paper fills this knowledge gap and experimentally validates the suitability and performance of CGAC in underwater vehicle applications. The standard MRAC is used as the baseline for performance comparison. Experimental results showed that CGAC achieves a low frequency control signal through low gain values and improves transient performance through modifications to the command signal. In addition, the ability of CGAC to overcome disturbances such as tether forces, and tolerate faults such as partial thruster failure was confirmed. Another interesting feature observed in these experiments is the ability of CGAC to operate despite the thruster dead zone, which standard MRAC is unable to perform without a dead-zone inverse. Therefore, according to the results CGAC performs better than standard MRAC and thus is a promising solution for future underwater vehicle applications.