Research on the coupling kinematics and workspace of rigid-flexible hybrid coal bunker cleaning robot

Coal bunker blockages severely affect transportation efficiency, while manual cleaning poses high labor intensity, frequent accidents, and significant safety risks. To address these issues, a rigid-flexible hybrid coal bunker cleaning robot is proposed, and the research focuses on the coupled kinematic model and the generation of the workspace for the robot. Firstly, the rigid-flexible hybrid coal bunker cleaning robot, which integrates a primary cable-driven parallel mechanism with a secondary cleaning manipulator, is proposed. Secondly, the coupled kinematic model for the robot is established, and a genetic algorithm with global search capabilities is introduced to resolve the multi-solution and complex nature of the inverse kinematics of the robot. Subsequently, the force-enclosed workspace for the rigid-flexible hybrid coal bunker cleaning robot is constructed and generated considering the constraints such as coal bunker geometry, cable length limits, tension thresholds, and collision prevention, and furthermore, two workspace quality indicators are proposed for the robot: the workspace coverage rate and configuration flexibility. Finally, the proposed coupled kinematic model and workspace of the rigid-flexible hybrid coal bunker cleaning robot are analyzed through simulation. The results demonstrated that the inverse kinematics solutions for the desired trajectory, when validated via forward kinematics simulation, yielded end-effector trajectories that closely matched the desired ones, thereby confirming the reliability of the inverse solution method. Quantitative workspace analysis reveals that the force-enclosed workspace of the robot achieves high coverage in critical blockage-prone zones, with uncovered areas primarily concentrated in non-critical regions such as the bunker inlet. In-depth analysis of the configuration flexibility space demonstrates optimal configuration flexibility in the central bunker region. While flexibility decreases with descending operational position, it remains sufficient to meet basic task requirements. As a result, the proposed rigid-flexible hybrid coal bunker cleaning robot exhibits potential applicability in structural design, kinematic characteristics, and workspace coverage, offering a more reliable and efficient solution for the automated cleaning of coal bunker blockages.