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Autonomous Underwater Vehicles Part 10

Tham khảo tài liệu 'autonomous underwater vehicles part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fully Coupled 6 Degree-of-Freedom Control of an Over-Actuated Autonomous Underwater Vehicle 169 Control System Accumulated Absolute Translational Error Accumulated Absolute Rotational Error Uncoupled System 1.3173x104 metres 8.3713x103 radians Coupled System 1.2003x104 metres 6.7580x103 radians Table 1. Accumulated Absolute Translational and Rotational Errors. 5. Conclusions Due to the increased adoption of AUVs for civilian and defence operations accuracy and reliability are two key factors that enable an AUV to successfully complete its mission. The control system is just one of the various components within the autonomy architecture of an AUV that helps in achieving this goal. Within the control system the control law should be robust to both external disturbances and model parameter uncertainties while the control allocation should utilise the various actuators of the vehicle to apply the desired forces to the vehicle while minimising the power expended. PID control has been successfully implemented on a variety of systems to effectively provide compensation. However since PID control is better suited to linear models the level of performance provided by PID control is not to the same standard as other particularly nonlinear control schemes when applied to complex nonlinear systems. Sliding mode control has proven to be a control law that is robust to parameter uncertainties and therefore is a prime candidate for implementation within this context due to the highly complex coupled nonlinear underwater vehicle model. Active utilisation of the coupled structure of this model is what coupled SMC attempts to achieve such that induced motion in one DoF due to motion in another DoF is adequately compensated for. This is where coupled SMC has a distinct advantage over uncoupled SMC for trajectory tracking applications when multiple DoFs are excited at once. Various schemes exist for control allocation with the ultimate goal being to apply the desired generalised .