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Wheelchair users (WCUs) face additional challenges than non-WCU to multi-tasking (i.e. open doors, cook, use a cell-phone) while navigating their environments. While assistive devices have attempted to provide WCUs with mobility solutions that enable multi-tasking capabilities, current devices have been developed without the input of end-users and have proven to be non-usable. More balanced approaches that integrate the end-users’ voices may improve current assistive technology usability trends. This study sought to empathically understand the lived experience of WCUs, their needs towards a mobility device, and their perceptions towards hands-free mobility. Full-time WCUs and care providers participated in semi-structured interviews examining wheelchair use and perceptions towards current and future mobility devices. Thematic analysis was used to analyze interview data. 9 WCUs (aged 32.1 ± 7.0 years; wheelchair experience 17.9 ± 11.6 years) and five care providers (years caring for WCU 3.75 ± 0.96 years) participated in the study. The most common disability type was spinal cord injury (WCUs: n = 3; care providers: n = 3). Qualitative analysis revealed four key themes: (1) Current wheelchair usage, (2) WCU and care provider perspectives, (3) Future wheelchair, and (4) Hands-free wheelchair. Accordingly, participants desire bespoke, light-weight mobility devices that can through tight spaces, access uneven terrain, and free the hands during navigation. This study provides meaningful insight into the needs of WCUs and care providers that assistive technology innovators can use to develop more usable assistive technologies. Amongst study participants, the concept of a hands-free mobility device appears to be usable and desirable. 

A novel wheelchair called PURE ( Personalized Unique Rolling Experience) that uses hands hands-free (HF) torso leanlean-to -steer control has been developed for manual wheelchair users (mWCUs). PURE addresses limitations of current wheelchairs, such as the in ability to use both hands for life experiences instead of propulsion. PURE uses a ball ball-based robot drivetrain to offer a compactcompact, selfself- balancing , omnidirectional mobile device. A custom sensor system convertconverts 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 human- robot interface and mWCUsmWCUs, performed as well as able able-bodied users (ABUs). 10 mWCUs and 10 ABUs were trained and tested to drive PURE through courses replicating indoor settingssettings. Each participant adjusted ride sensitivity settings for both HF and JS control . Repeated Repeated-measures MANOVA tests suggested that the number of collisions collisions, completion time time, NASA TLX scores except physical demand , and index of performance performances were similar for HF and JS control and between mWCUs and ABUs for all sections. Th is suggestsuggests that PURE is effective for controlling this new omnidirectional wheelchair by only using torso motion thus leaving both hands to be used for other tasks during propulsion propulsion. 

The current state of function and design of accessible assistive technology is lacking, evidenced by low usability and high abandonment rates by people with disabilities (PwD). A significant contributing factor to these negative outcomes is a lack of user-centered design or user-opinion in the product development. The Human Performance and Mobility Maker Lab (HPML) at the University of Illinois Urbana-Champaign is a new facility dedicated to developing assistive technology by PwDs. Rather than being excluded from the design and innovation process, PwDs are the primary drivers of innovation at the HPML. The HPML’s the central tenet is ‘Designed by, not designed for’. The purpose of this paper is to explore various assistive technologies developed in the HPML while providing an empathic framework for other research groups to follow in integrating PwDs into the development and design of assistive technology. 

This paper presents the design and control of a ballbot drivetrain that aims to achieve high agility, minimal footprint, and high payload capacity while maintaining dynamic stability. Two hardware platforms and analytical models were developed to test design and control methodologies. The fullscale ballbot prototype (MiaPURE) was constructed using offthe- shelf components and designed to have agility, footprint, and balance similar to that of a walking human. The planar inverted pendulum testbed (PIPTB) was developed as a reduced-order testbed for quick validation of system performance. We then proposed a simple yet robust cascaded LQR-PI controller to balance and maneuver the ballbot drivetrain with a heavy payload. This is crucial because the drivetrain is often subject to high stiction due to elastomeric components in the torque transmission system. This controller was first tested in the PIPTB to compare with traditional LQR and cascaded PI-PD controllers, and then implemented in the ballbot drivetrain. The MiaPURE drivetrain was able to carry a payload of 60 kg, achieve a maximum speed of 2.3 m/s, and come to a stop from a speed of 1.4 m/s in 2 seconds in a selected translation direction. Finally, we demonstrated the omnidirectional movement of the ballbot drivetrain in an indoor environment as a payload-carrying robot and a human-riding mobility device. Our experiments demonstrated the feasibility of using the ballbot drivetrain as a universal mobility platform with agile movements, minimal footprint, and high payload capacity using our proposed design and control methodologies. 

A hands-free (HF) lean-to-steer control concept that uses torso motions is demonstrated by navigating a virtual robotic mobility device based on a ball-based robotic (ballbot) wheelchair. A custom sensor system (i.e., Torso-dynamics Estimation System (TES)) was utilized to measure and convert the dynamics of the rider’s torso motions into commands to provide HF control of the robot. A simulation study was conducted to explore the efficacy of the HF controller compared to a traditional joystick (JS) controller, and whether there were differences in performance by manual wheelchair users (mWCUs), who may have reduced torso function, compared to able-bodied users (ABUs). Twenty test subjects (10 mWCUs + 10 ABUs) used the subject-specific adjusted TES while wearing a virtual reality headset and were asked to navigate a virtual human rider on the ballbot through obstacle courses replicating seven indoor environment zones. Repeated measures MANOVA tests assessed performance metrics representing efficiency (i.e., number of collisions), effectiveness (i.e., completion time), comfort (i.e., NASA TLX scores), and robustness (i.e., index of performance). As expected, more challenging zones took longer to complete and resulted in more collisions. An interaction effect was observed such that ABUs had significantly more collisions using JS vs. HF control, while mWCUs had little difference with either interface. All subjects reported greater physical demand was needed for HF control than JS control; although, no users visibly showed or expressed fatigue or exhaustion when using HF control. In general, HF control performed as well as JS control, and mWCUs performed similarly to ABUs. 

We designed and validated two interfaces for physical human-robot interaction that utilize torso motions for hands-free navigation control of riding or remote mobile robots. The Torso-dynamics Estimation System (TES), which consisted of an instrumented seat (Force Sensing Seat, FSS) and a wearable sensor (inertial measurement unit, IMU), was developed to quantify the translational and rotational motions of the torso, respectively. The FSS was constructed from six uniaxial loadcells to output 3D resultant forces and torques, which were used to compute the translational movement of the 2D center of pressure (COP) under the seated user. Two versions of the FSS (Gen 1.0 and 2.0) with different loadcell layouts, materials, and manufacturing methods were developed to showcase the versatility of the FSS design and construction. Both FSS versions utilized low-cost components and a simple calibration protocol to correct for dimensional inaccuracies. The IMU, attached on the user’s upper chest, used a proprietary algorithm to compute the 3D torso angles without relying heavily on magnetometers to minimize errors from electromagnetic noises. A validation study was performed on eight test subjects (six able-bodied users and two manual wheelchair users with reduced torso range of motion) to validate TES estimations by comparing them to data collected on a research-grade force plate and motion capture system. TES readings displayed high accuracy (average RMSE of 3D forces, 3D torques, 2D COP, and torso angles were well less than maximum limits of 5N, 5Nm, 10mm, and 6˚, respectively).