Intelligent Calibration of a Heavy-Duty Mechanical Arm in Coal Mine

Abstract

Accurate positioning of an airborne heavy-duty mechanical arm in coal mine, such as a roof bolter, is important for the efficiency and safety of coal mining. Its positioning accuracy is affected not only by geometric errors but also by nongeometric errors such as link and joint compliance. In this paper, a novel calibration method based on error limited genetic algorithm (ELGA) and regularized extreme learning machine (RELM) is proposed to improve the positioning accuracy of a roof bolter. To achieve the improvement, the ELGA is firstly implemented to identify the geometric parameters of the roof bolter’s kinematics model. Then, the residual positioning errors caused by nongeometric facts are compensated with the regularized extreme learning machine (RELM) network. Experiments were carried out to validate the proposed calibration method. The experimental results show that the root mean square error (RMSE) and the mean absolute error (MAE) between the actual mast end position and the nominal mast end position are reduced by more than 78.23%. It also shows the maximum absolute error (MAXE) between the actual mast end position and the nominal mast end position is reduced by more than 58.72% in the three directions of Cartesian coordinate system.

Elasto-Geometrical Model-Based Control of Industrial Manipulators Using Force Feedback: Application to Incremental Sheet Forming

“…The fourth method is a model-based compensation, where prior knowledge of the machine's behavior is needed. Although a geometrical calibration of a loaded robot can virtually correct those imperfections by adding extra geometrical parameters or modifying existing ones [17][18][19][20][21][22], it does not correspond to the physical behavior of the manipulator. Indeed, there is no proportionality between the force input and the deformation of the machine, so it is only valid for a constant load scenario.…”