Novel design of GFRP beam spring rocker-arm suspension for 6-wheeled mobile robots

Six-wheeled mobile robots (6-WMRs) equipped with rocker-bogie suspension systems are widely used for planetary exploration and search-and-rescue tasks due to their excellent terrain adaptability. However, conventional rocker-bogie-based systems present critical limitations, including tire slip caused by the absence of steering mechanisms, lack of camber control, and increased structural complexity from added components. To overcome these issues, this study introduces the GFRP Beam Spring Rocker-arm Suspension (GBSRS), which integrates a rocker-arm structure with a Glass Fiber Reinforced Polymer (GFRP) beam spring. An independent steering system based on Ackermann geometry is applied to minimize tire slip, while the torsional and vertical compliance of the GFRP beam enables passive camber variation and vibration damping without the use of additional actuators or complex linkages. A 7-degree-of-freedom (7-DOF) vibration model is developed to simulate dynamic behavior, and a bend-twist coupling analysis is conducted to calculate beam deformation and camber response. The design is further optimized by applying Derringer’s desirability function to key parameters such as beam thickness, damper position, and camber adjuster angle. Simulation and experimental results—including tests over single obstacles and rough terrain—demonstrate that the GBSRS reduces RMS acceleration by up to 16.3% and peak acceleration by up to 40.6% compared to conventional solid-arm systems. These results confirm that the GBSRS effectively improves vibration isolation and camber adaptability while maintaining structural simplicity, offering a practical suspension solution for 6-WMRs in challenging environments.