SUMMARY

Helicopters are versatile vehicles that can serve a variety of roles. One role is that of a "flying crane" -- a load is suspended from the helicopter by a cable, and the helicopter carries it to a target location. Unfortunately, the load naturally swings, which degrades control of the helicopter and makes it difficult for the pilot to put the load back on the ground. Control techniques designed to reduce this detrimental load swing have mainly relied on feedback of the load position, which is rarely available in modern full-scale helicopters. This thesis investigates the use of input shaping for reducing the load swing problem. Input shaping is a command-filtering technique that has improved the performance of many types of machines with unwanted flexibility, and does not require feedback. The investigation is conducted using two different, but complementary, approaches. One approach studies manual tracking tasks, where humans attempt to make a cursor follow an unpredictably moving target. The second approach studies horizontal repositioning maneuvers on two small-scale helicopter testbeds. These approaches are used to analyze how input shaping affects position control of a flexible element (the suspended load) and an inflexible element (the helicopter). The presentation identifies specific input shapers and control-system implementations that yield the largest benefits for the helicopter-load system in particular, and for flexible human-controlled systems in general.