Stair-climbing wheelchair proven to maintain user's body stability based on AnyBody musculoskeletal model and finite element analysis

The electric stair-climbing wheelchair is a beneficial mobile assistance device for older adults and disabled persons with poor walking ability, as it reduces the daily walking and climbing burden. In this paper, 11 older adults were tested when using a stair-climbing wheelchair in three environments: flat ground, slopes, and stairs. The kinematic and dynamic parameters of the lower limb joints were simulated by AnyBody 7.2 human model simulation software using Vicon 3D infrared motion capture, a 3D force table, and analyzed by ANSYS 19.2 Workbench. The joint force, joint moment, and muscle strength did not change significantly under the three environments when using the wheelchair. Through finite element analysis of the mechanical properties of the human body, when using the wheelchair, no significant differences in the overall stress distributions of the fifth lumbar spine, hip bone, or femur were found among the three environments, no significant differences in deformation and displacement were found, and the stress distribution was relatively stable. Therefore, the human body is stable enough to use the electric stair-climbing wheelchair in the three test environments, all of which will be commonly encountered in daily life.