Structural Design and Research on a Novel Multifunctional Nursing Wheelchair Robot

For various challenges faced by elderly individuals with physical disabilities in home-based care, a novel multifunctional nursing wheelchair robot, named M-nur, is proposed to meet the care assistance needs of elderly individuals in home-based care. M-nur integrates features such as omnidirectional movement, multi-posture transformation, toilet docking, and bathing assistance. To address the relative slip of the knee joint during posture transformation, an active compensation based posture-changing linkage structure is designed, with the dimensions of key linkages determined by minimizing the sagittal plane area optimization function. For the toilet module, a resettable toilet seat structure is designed to minimize space occupancy, and the linkage length is optimized, while the dynamics of the reset spring force are modeled. Additionally, the kinematic model of the posture transformation structure is established, and the compensation effect for relative knee slip is analyzed through Adams simulation. Motion capture experiments on the prototype are conducted to validate the performance of the active compensation mechanism. The experimental results show that M-nur effectively compensates for the relative slip of the knee joint during posture transformation, with better compensation performance during the standing process than the reclining process. Furthermore, the prototype is tested for toilet docking, and the lifting process is analyzed using encoders. The results indicate that M-nur is compatible with toilets having a seat height of 502 mm or less. Finally, elderly individuals are invited to compare M-nur with similar products. The results show that although M-nur performs well functionally, the backrest needs to be replaced with smoother leather, and the safety straps need to be used in conjunction with rigid guardrails to enhance safety.