(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1993-08)
Keefe, Robert W.
Control systems for underwater vehicles have reached the level of sophistication
where they are limited by the dynamic performance of the thrust actuators. Standard
fixed-pitch propellers have been shown to have very poor dynamic characteristics,
particularly at low thrust levels The dynamic response of a fixed-pitch propeller is
dependent upon highly non-linear transients encountered while the shaft speed approaches
its steady-state value. This thesis proposes the use of a controllable pitch propeller system
to address this problem. A controllable pitch propeller varies the amount of thrust
produced by varying the pitch angle of the blades at a constant shaft speed. The bandwidth
of this type of thrust actuator would be dependent primarily on the speed at which the
pitch angle of the blades are changed. A variable pitch propeller system suitable for retrofit
into an ROV is designed and built. The system is designed for maximal pitch angle
bandwidth with low actuator power consumption.
