Virtual Reality Based Testing of Power Wheelchair Driving Skills
Condition: Spinal Cord Injury; Spina Bifida; Spinal Cord Disease
MeSH terms: Spinal Cord Injuries; Spinal Dysraphism; Spinal Cord Diseases
Study type: Observational

Summary: 
      The purpose of this research study is to examine whether computer based or virtual reality
      based driving assessments are as useful as real-world power wheelchair driving tests in
      measuring driving performance and whether they may be useful in helping to identify the
      problems that some individuals may have with driving power wheelchairs. The specific aims are
      as follows:

      Specific Aim 1: To develop computer-based and VR-based wheelchair driving assessments for
      both drivers and non-drivers that correspond to an accepted real-world driving assessment
      (Power Mobility Road Test) and compare them to the real-world assessment and to each other.

      Specific Aim 2: To develop additional features of the computer-based and VR-based assessments
      that present dynamic tasks and determine whether skills on these tasks can be delineated
      within the virtual environment.
    

Detailed description: 
      This study has an experimental, repeated measures design with validity and reliability
      testing. In Phase 1 of the study, we designed and developed the software needed to deliver
      the computer-based and VR-based testing environments. In Phase 2 of the study, we improved on
      the design iterations of Phase I, recruited a sample of 31 Electric Power wheelchair (EPW)
      users and delivered the simulator based driving assessment using a pool of clinicians to
      assess the reliability of system in real world and in the virtual environments.

      Phase II: Research Protocol:

      Experimental Set-up:

      VRSIM consisted of two display options, three 6' X 8' back projected screens (field of view
      160°) (VR screens) and a single 22" desktop monitor (field of view 90°) (PC screens), both
      with the first-person perspective viewpoint (Fig.1). The virtual environment consisted of a
      simulation of an indoor office space with a kitchen; a lounge area and set of hallways lined
      by offices, and incorporated the tasks of the PMRT (Fig.2). Participants interacted with
      VRSIM either using dual rollers that interfaced with drive wheels of the wheelchair ('Rollers
      ON' driving mode) or using an instrumented wheelchair joystick through a custom software
      ('Rollers OFF' driving mode). The custom software uses a proportional derivative mathematical
      model to simulate the real-world motion of the EPW within the virtual environment. VRSIM was
      designed with two display options and two user input modalities to assess the feasibility of
      using such a system with different interfaces in different settings, such as in a busy
      wheelchair clinic (using the much immersive VR screens with rollers) or in a user's home
      (with the user's personal computer and the customized joystick).

      The "actor/driver" in the VRSIM was a virtual model of a person sitting in a standard
      commercially available EPW power wheelchair (width 0.671 m, length 0.701 m). A horizontal
      slider bar that indicated the real time location of the virtual wheelchair with respect to
      virtual obstacles was added to this version (Fig.1, 2). This helped display warnings when the
      chair was too close to obstacles, especially when the obstacles were behind the driver.
      Participants were expected to drive along the course indicated by arrows touching or passing
      through preset milestone markers signified by semi-transparent balloons. These sequentially
      displayed milestones defined the tasks of the virtual PMRT. Participants were instructed to
      complete every task as quickly and accurately as possible. An equivalent PMRT driving course
      was charted out in an office space for the real world driving evaluation.

      Data collection:

      After informed consent, participants performed up to 2 practice sessions within the virtual
      driving course. Participants reported their level of comfort and sense of being in control in
      the VRSIM during practice based on which a value between 1.0 and 4.0 was selected for the
      linear and angular speed gains in VRSIM. In addition, participants were asked to select a
      different pre-programmed driving profile on their wheelchairs (e.g. "indoor" profile), which
      was similar to their everyday driving profile to obtain optimum driving speed. Optional
      breaks for 5-10 minutes were provided between driving sessions. For both the PC and VR
      screens, participants drove through the complete driving course: two trials with the Rollers
      ON driving mode, one trial with the Rollers OFF driving mode, and one trial in the real-world
      PMRT driving course constituted to a total of 5 driving conditions (Table 1). A balanced
      randomization scheme was used to set the order of the five driving conditions.

      From a group of 6 clinicians comprised of 1 occupational therapist, 3 physical therapists,
      and 2 physicians, 2 clinicians were randomly assigned as the evaluation team for each
      participant. The team always had 1 certified Assistive Technology Professional with more than
      5 years of experience in power wheelchair driving evaluations. The assigned clinicians
      independently scored every PMRT task during all the driving trials using the following
      criteria: 4: completed independently, 3: completed hesitantly requiring several trials and
      minor accidents, 2: commits serious accidents that may cause harm to driver or other people,
      1: unable to complete a task. Each clinician had a separate PMRT scoring sheet for each
      trial.

      Repeat Testing:

      Subjects underwent all five testing scenarios twice, returning on a second visit in no
      earlier than 2 weeks.
    

Intervention name(s): Power Mobility Road Test (PMRT)
Intervention type(s): Other
Intervention description(s): All subjects will underwent the Power Mobility Road Test (PMRT), and the clinicians scored the driving performance within each condition.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        People with physical disabilities who have a mobility impairment due to any any spinal cord
        disease condition (e.g. Spinal Cord Injury, Spina Bifida)
      
Keywords: Electric power wheelchair driving; rehabilitation; driving assessments