Research on mechanical properties of the launching mechanism of the RoboMaster

Abstract

To address the complex dynamic behavior and inadequate firing accuracy of the 42 mm projectile launching system of the hero robot in the RoboMaster competition, this paper designs and improves a dual friction-wheel pinch-type launching mechanism. A mechanical model of the launching process is established based on the viscoelastic constitutive equation of polyurethane materials and a modified Hertz contact theory. Transient dynamic simulations are conducted to analyze the effects of the center distance between the two friction wheels (ranging from 95 mm to 99 mm) on the projectile’s exit velocity and the stress distribution inside the friction wheels. Simulation results indicate that at a center distance of 95 mm, stress concentration exceeds the yield limit of the material, causing projectile jamming. For center distances between 96 mm and 99 mm, the mechanism operates safely, with the 97 mm spacing achieving the highest energy transfer efficiency and the maximum projectile exit velocity. To validate the simulations, an experimental platform is established. Launch tests are carried out at three friction wheel rotational speeds (5000 rpm, 6000 rpm, and 7000 rpm) for four center distances (96 mm, 97 mm, 98 mm, and 99 mm). Experimental results consistently show that under all three speed conditions, the 97 mm spacing yields the highest and most stable initial launch velocity, with approximately 90% of the test data reaching the maximum initial speed value. This study reveals the nonlinear influence mechanism of friction wheel center distance on launch performance, providing theoretical support and quantitative references for improving the firing accuracy and operational reliability of launching mechanisms in competitive robots.