When lifting up a long slender beam from ground, the payload may slip or move suddenly in unintended and unpredictable ways. This occurs during crane operations when the movements of the overhead trolley and the hoist cable are not properly coordinated. Also, it is difficult to keep the centers of hook and payload mass aligned with the pivot point when the payload is lifted off the ground, resulting in undesired hook and payload swing. The payload’s unintended sliding or swing can potentially cause damage and reduce efficiency. This paper divides the lift-up process into two phases including a constrained phase and a free hanging phase, develops a combination of PID controller and speed envelope to prevent slip in the constrained phase, and presents an observer-based Linear Quadratic Regulator (LQR) control strategy to stabilize the double-pendulum oscillations in the free hanging phase. The robustness of the proposed observer-based LQR was analyzed. Lift-up experiments were carried out to verify the controller development.

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