Global Integral Sliding-Mode Control With Improved Nonlinear Extended State Observer for Rotary Tracking of a Hydraulic Roofbolter

To effectively control the drilling of a hydraulic roofbolter is of importance because inappropriate rotary speed may lead to the collapse of roof in a roadway. Two difficulties facing for controlling a rotation system are its inherent characteristics, including dead zone and disturbance, and the specific performance requirement, such as no overshoot and chattering. To address the issues, a novel integral sliding-mode control (NISMC) with improved nonlinear extended state observer and uncertain gain adaptive law is proposed. A rotation system is first modeled after compensating dead zone. NISMC composed of an active disturbance rejection control (ADRC) unit, a sliding-mode control (SMC) unit, and an adaptive unit is then developed. In the ADRC unit, an improved nonlinear extended state observer is presented to efficiently estimate disturbances and suppress noise. In order to achieve a robust tracking performance, a novel sliding-mode control law is designed in the SMC unit, and the adaptive unit is put forward to deal with uncertain gain. Experimental results on a practical rotation system show that the proposed method tracks the expected rotary speed with better dynamic and steady-state performance, especially without overshoot.