Dynamics and Control of the Bucket-Wheel Excavator: Part II — Vibration Control of Bucket-Wheel Boom

Bucket-Wheel excavators (BWE) represent a specific type of complex machine system used in mining technology. During operation, the system is exposed to a number of external forces and disturbances like digging resistances on the Bucket-Wheel that cause transverse, longitudinal, and torsional vibrations. All vibrations will be affected to normal working conditions, operational effectiveness, and may under specific conditions also effect the stability of the BWE. Taking into account nonlinear effects due to the higher-order geometrical and dynamical couplings of flexible deformations modeled under guided motions in combination with digging resistance forces result to the adequately dynamic behavior of the Bucket-Wheel boom, introduced in the first part. Additionally, it also leads to difficulties controlling the nonlinear dynamic system. To overcome these difficulties here the nonlinear dynamical system is approximated by an equivalent linear system linearized for suitable working points of remaining and not considered additive nonlinear parts of the system. In this contribution, based on the nonlinear characteristic of the system, the time behavior of nonlinearities (as additive effects in relation to the linearized system) is estimated in combination with related system states using a high-gain extended state observer. Then the well-known disturbance rejection control approach is used for vibration control of this nonlinear mechanical system. Simulation examples are included to illustrate the efficient suppression of vibrations as well as stabilization of the system during the digging process of Bucket-Wheel Excavator.