Spatial kinematics analysis of a rotary-percussive blasting drill manufactured in Vietnam

This article investigates the kinematic behavior of a domestically manufactured rotary-percussive blasting drill in Vietnam, focusing on forward and inverse kinematic analyses to optimize its workspace for small to medium tunnel cross-sections. This work distinguishes itself by addressing the unique constraints of confined military tunnels through a novel design modification enabling 360° rotation of Link 4, bridging the gap between theoretical kinematics and cost-effective local production. A real-world survey and Denavit–Hartenberg (D–H) model were used to determine the original reachable envelope, revealing a lowest drill bit position of +0.1784 m, which fails to meet construction requirements. Inverse kinematics via the Newton–Raphson method identified joint solutions for boundary points A (3.2, 0, 2.7), B (3.2, −0.8, 2.1), C (3.2, −0.8, 0.1), and D (3.2, −0.265, 0.1), leading to the proposed modification. Simulations in MATLAB/Simulink validated the approach, extending the lowest position to −0.2092 m (increased by 0.3876 m), with position errors between 10 −3 and 10 −4 m. The results provide a scientific foundation for enhancing drilling precision and accessibility, reducing reliance on imported equipment.