Driving a Ballbot Wheelchair with Hands-Free Torso Control

A novel wheelchair called PURE (Personalized Unique Rolling Experience) that uses hands-free (HF) lean-to-steer control has been developed for manual wheelchair users (mWCUs). PURE addresses limitations of current wheelchairs, such as inability to use both hands for life experiences instead of propulsion, and bulky and heavy powered wheelchairs. PURE uses a ball-based robot (ballbot) drivetrain to offer a compact, self-balancing device with the added benefit of omnidirectional movement ability. A custom sensor system converts rider torso motions into direction and speed commands to control PURE, which is especially useful if a rider has minimal torso range of motion. We explored whether PURE’s HF control performed as well as a traditional joystick (JS) human-robot interface and mWCUs, who may have reduced torso motion, performed as well as able-bodied users (ABUs). Twenty test participants (10 mWCUs, 10 ABUs) were trained and tested to drive PURE through courses replicating indoor environments. Each participant adjusted personal sensitivity settings for both HF and JS control. Repeated-measures MANOVA tests suggested that the effectiveness (number of collisions), efficiency (completion time), comfort (NASA TLX scores except physical demand), and robustness (index of performance) were similar for HF and JS control and between mWCUs and ABUs for all sections. These results suggest that PURE provides an effective method for controlling this new omnidirectional wheelchair by only using motions of the torso (including small movements) thus leaving both hands to be used for other tasks while the rider is moving about.