Modeling and Design of a Stair Climbing Wheelchair with Pose Estimation and Adjustment

Urban locomotion is a challenge for individuals with lower limb impairment or any other conditions that inhibit ambulation. While wheelchairs are the absolute choice, they do not address the entire problem of accessibility in urban locomotion despite the use of actuators. One of the viable prospects has been demonstrated by Stair Climbing Wheelchairs (SCW), which rely on different modes of mechanism to traverse the staircase. Since staircases are the most common and one of the challenging elements of the urban setting, these wheelchairs are supposed to sufficiently address the problems of the terrain. However, several technical and psychological shortcomings hinder a wider practical use. This paper discusses semi-autonomous tracked SCW and introduces a novel kinematic mechanism design that facilitates successful switching of the mode of locomotion and autonomous pose adjustment with the changing terrain. To execute the intended task of pose estimation/adjustment and variable locomotion, an algorithm that combines multiple sensor data with the kinematic model has been developed. The developed prototype was tested in a loaded condition in staircases of different gradients. The experimental results suggest that the system addresses a plethora of issues mentioned in the literature, considering the factors of accessibility and safety. Also, this paper has highlighted the requirement of vibration suppression for user comfort, promoting technological acceptance and adaptation.