Robust design of air chamber to enhance impact connection strength of magnetic connectors on modular truss robots

Abstract

Abstract

The connection mechanisms between neighboring modules are crucial subsystems in modular reconfigurable robot (MRR) systems. Magnetic connectors have been widely used for docking and undocking because of their mechanical simplicity and ease of use. However, they suffer from lower maximum tensile strength compared with mechanical docking mechanisms. This limitation is critical when modular truss robots are subjected to impact forces during locomotion, reconfiguration, docking, and undocking. To address this challenge, this paper presents a comprehensive parametric study and establishes design guidelines to maximize the impact resistance of magnetic connectors. As a core component of this approach, we investigate a mode-switching silicone air chamber designed to enhance impact absorption while mitigating the degradation of undocking capabilities. To evaluate the performance of the air chamber, we introduce an experimental evaluation method inspired by the Charpy impact test. Because the transient response of the soft structure is highly complex, the Taguchi and full factorial design method were employed to optimize the design parameters and derive the design guidelines. In the case of parameters, four factors were selected that could be judged to have an impact on the pneumatic stiffness, structural flexibility, and fluid damping of the air chamber. Also, each design parameter was divided into three levels, and five replicate experiments were conducted for each combination using an \(L_9(3^4)\) orthogonal array. The performance metrics consist of the sum of weighted values of \(M_1\) , which indicates the air chamber’s resistance to impact, and \(M_2\) , which reflects the indicator of mode switching between opening and closing the air chamber’s bottom hole. To explore the vicinity of the optimal value identified in the first experiment, a second experiment was conducted to pinpoint the final optimal parameter configuration, achieving a metric improvement of 0.051969 over the worst-case scenario. Finally, the practical feasibility and effectiveness of the proposed design guidelines were demonstrated through a hardware model using a prototype connector within a configured MRR system, demonstrating connection retention under selected impact conditions.