Cartbot: A Direct-Manipulation Minimal Degrees-of-Freedom Mobile Assistive Robot to Maximize User Agency

This paper presents Cartbot, a low-cost assistive mobile manipulator robot with a minimal degree-of-freedom (DOF) design approach that allows people with tetraplegia complete manual control over its kinematics. Most assistive mobile manipulation research focuses on enabling control of complex robots with many DOFs using input devices with limited DOFs by offloading full or partial control onto an autonomous control system. Automating control denies the user complete agency over the robot’s behavior and therefore limits freedom of use. In contrast, our approach aims to allow the user direct-manipulation control over the entire system by minimizing the DOFs of the robot design. The Cartbot consists of a cylindrical manipulator, a differential drive system, and a shopping-cart-based chassis. Feedback from initial user testing was unanimously positive and supported the effectiveness of our design approach in terms of both freedom and ease of use.