Hydraulic articulated multi-joint crane systems are widely used for the transportation of heavy loads. High productivity requires a short cargo transportation time which can lead to undesirable oscillations during crane load acceleration and deceleration. Typically it is the task of a crane operator to suppress the load swing, but with ever-increasing demand for faster operation the need for supporting control systems is evident. For overhead gantry cranes such assisting control systems can be considered as state of the art. However, for more complex articulated multi-link cranes only a few applicable control concepts have been proposed. Load swing angle and angular velocity measurement, or corresponding state observer based estimation, has been seen as a main problem in the realization of such assisting control systems. To tackle the problem, we present a novel suspended load anti-sway control system for heavy-duty articulated hydraulic cranes using solely low-cost linear MEMS accelerometers and angular rate gyroscopes embedded into easy-to-install sensor units. The proposed closed-loop anti-sway controller uses a network of embedded MEMS sensors for the crane motion state, suspended load inclination angle and angular velocity estimation. The control concept uses a semi-active approach where the desired load velocity is set by the crane operator via e.g. joystick input and the underlying load oscillation damping control system creates the desired crane tip velocity. Comparative results of anti-sway control are obtained using high resolution incremental encoder feedback for the articulated crane and suspended load motion states. Our experimental results verify effectiveness of the proposed anti-sway control system for articulated hydraulic cranes as well as applicability of the proposed MEMS sensor network for real-time closed-loop control of multi-body manipulators.

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