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Large amplitude oscillation of crane payloads is detrimental to safe and efficient operation. Under certain conditions, the problem is compounded when the payload creates a double-pendulum effect. Most crane control research to date has focused on singlependulum dynamics. Several researchers have shown that singlemode oscillations can be greatly reduced by properly shaping the inputs to the crane motors. This paper builds on those previous developments to create a method for suppressing doublependulum payload oscillations. The input shaping controller is designed to have robustness to changes in the two operating frequencies. Experiments performed on a portable bridge crane are used to verify the effectiveness of this method and the robustness of the input shaper.

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Systems that exhibit flexible dynamics are widespread and present a very challenging control problem when their performance is pushed to the limit. If there is some knowledge of the flexible modes, then command signals can be generated to negate the detrimental dynamics. These vibration-reducing commands are dependent on the feedback controller gains because the gains influence the flexible modes. This paper presents a method for concurrently designing a PD feedback controller and a command generator so that performance is optimized. The design method takes into account limits on allowable overshoot, residual vibration, and actuator effort. Furthermore, the structure of the method allows a wide range of performance requirements, such as disturbance rejection, to be integrated into the design. Results demonstrate that a PD controller cannot achieve the same performance as a PD controller augmented with a command generator.

If the dynamic behavior of a flexible system is known, then commands can be generated to negate the detrimental dynamics. These commands are dependent on the feedback controller gains. This paper presents a method for concurrently designing the feedback controller and the command generator so that performance is optimized.

Sliding sleeves are used to enable selective zonal isolation and can improve water and gas management throughout the life of the well. Because of the large shifting force and extended reach required to operate sliding sleeves in long horizontals, coiled tubing is typically used. Coiled tubing also provides the benefit of pumping fluids to clean out or treat the well. A surface load measurement with coiled tubing may sometimes provide a positive indication of shifting, but not in all cases. Also, surface measurements alone do not provide a way to determine the sleeve position. This paper describes conventional techniques used to confirm proper shifting and determine sleeve position. An improved method is presented, along with yard and field test results.