SeaHare: An omnidirectional electric wheelchair integrating independent, remote and shared control modalities
Giulia Barbareschi, Ando Ryoichi, Midori Kawaguchi, Minato Takeda, Kouta Minamizawa · 2024 · ASSETS '24: Proceedings of the 26th International ACM SIGACCESS Conference on Computers and Accessibility · doi:10.1145/3663548.3675657
Summary
This paper presents SeaHare, an omnidirectional electric wheelchair that integrates three control paradigms — independent, remote, and shared — within a single platform, enabling direct comparison of how different control modes affect the experience of both wheelchair riders and controllers. The wheelchair uses a novel interface: two sensing seats that detect shifts in the user's centre of gravity to steer. One sensing seat is mounted on the wheelchair itself, allowing the rider to control movement by leaning; the second is a separate remote seat that a companion or caregiver can use to steer the wheelchair from a distance. The omnidirectional drive system (using Mecanum wheels) allows the chair to move in any direction — forward, backward, sideways, and diagonally — as well as rotate in place, providing manoeuvrability that conventional wheelchairs cannot achieve. In independent mode, only the rider's seat input controls the wheelchair; in remote mode, only the companion's seat controls it; in shared mode, both inputs are combined, allowing collaborative steering. The researchers conducted a user study with 5 dyads and 1 triad (11 participants total, including both wheelchair users and non-users) who tested all three control modes through an obstacle course and open exploration. Data was collected through task performance metrics, video observation, semi-structured interviews, and questionnaires measuring perceived control, trust, comfort, and collaboration quality.
Key findings
Each control mode had distinct advantages and challenges shaped by participants' skills and lived experiences. Independent mode was preferred by experienced wheelchair users who valued autonomy and found the centre-of-gravity interface intuitive, though some participants with limited trunk control found it difficult. Remote mode was valued for situations where the rider could not see obstacles (approaching from behind) or lacked the physical ability to steer, but riders reported reduced sense of agency and some discomfort at being moved without personal control — one participant compared it to being pushed in a manual wheelchair without being asked first. Shared mode produced the most complex and interesting results: when dyads successfully negotiated their inputs, shared control felt collaborative and empowering, with riders describing it as "driving together." However, conflicting inputs (one person leaning left while the other leaned right) caused confusion and unpredictable movement, highlighting the need for clear communication protocols. The omnidirectional capability was universally valued, particularly lateral movement which participants noted would be transformative in tight spaces like elevators, narrow aisles, and crowded rooms. The centre-of-gravity interface was praised for being hands-free — important for users who need their hands for other tasks — but the learning curve varied significantly. Experienced wheelchair users adapted quickly, while participants without wheelchair experience found it initially unintuitive. Participants envisioned scenario-specific mode switching: independent for familiar routes, shared for crowded events, and remote for situations where a companion has better visual information.
Relevance
SeaHare advances wheelchair technology in two significant directions: omnidirectional mobility and flexible control paradigms. The omnidirectional capability addresses a real-world barrier that conventional wheelchairs create — the inability to move sideways makes navigating tight spaces, queueing, and positioning at tables or desks unnecessarily difficult. The three-mode control system embodies the interdependence framework emerging in disability research: rather than designing solely for independent use or solely for caregiver control, SeaHare supports a spectrum of control sharing that can adapt to the user's abilities, context, and preferences. This directly challenges the binary of "independent" versus "dependent" that pervades assistive technology design. For accessibility practitioners, the finding that shared control requires explicit communication and negotiation protocols is relevant to any collaborative assistive technology. The centre-of-gravity interface also represents an important alternative input modality for users who cannot operate joysticks or switches, expanding the population who can drive electric wheelchairs independently.
Tags: wheelchair · electric wheelchair · omnidirectional · shared control · remote control · centre of gravity · assistive technology · collaborative control · interdependence