Analytical Investigation of Tire-Road Contact Characteristics for Wheelchair Robots Safely Running

To effectively improve the tire grounding behaviors of wheelchair robots, an analytical method is proposed to analyze and optimize the tire grounding safety. Firstly, taking the cushion and tires as the vibration isolation elements with stiffness and damping, the vertical vibration model of the human-wheelchair robot is established. Then, taking the random excitation as the typical input, the formulae of the TDD (tire dynamic deflection) frequency response function H and the RMS (root mean square) response are derived and the response coefficient λ is proposed. Moreover, the influence laws of system parameters on H and λ are revealed. Thirdly, based on λ, the analytical optimization model for the cushion system damping ratio ξ2 is established. Finally, a case study and numerical simulation were carried out. The results show that the relative deviation of the cushion optimal damping is about 0.3%.