Development of a Wheelchair Virtual Driving Environment: Trials With Subjects With Traumatic Brain Injury

Abstract 

Spaeth DM, Mahajan H, Karmarkar A, Collins D, Cooper RA, Boninger ML. Development of a wheelchair virtual driving environment: trials with subjects with traumatic brain injury.

Objective

To develop and test a wheelchair virtual driving environment that can provide quantifiable measures of driving ability, offer driver training, and measure the performance of alternative controls.

Design

A virtual driving environment was developed. The wheelchair icon is displayed in a 2-dimensional, bird's eye view and has realistic steering and inertial properties. Eight subjects were recruited to test the virtual driving environment. They were clinically evaluated for range of motion, muscle strength, and visual field function. Driving capacity was assessed by a brief trial with an actual wheelchair. During virtual trials, subjects were seated in a stationary wheelchair; a standard motion sensing joystick (MSJ) was compared with an experimental isometric joystick by using a repeated-measures design.

Setting

Subjects made 2 laboratory visits. The first visit included clinical evaluation, tuning the isometric joystick, familiarization with virtual driving environment, and 4 driving tasks. The second visit included 40 trials with each joystick.

Participants

Subjects (n=8; 7 men, 1 woman) with a mean age of 22.65±2y and traumatic brain injury, both ambulatory and nonambulatory, were recruited.

Interventions

The MSJ used factory settings. A tuning program customized the isometric joystick transfer functions during visit 1. During the second visit, subjects performed 40 trials with each joystick.

Main Outcome Measure

The root mean square error (RMSE) was defined as the average deviation from track centerline (in meters) and speed (in m/s).

Results

Data analysis from the first 8 subjects showed no statistically significant differences between joysticks. RMSE averaged .12 to .21m; speed averaged .75m/s. For all tasks and joysticks, driving in reverse resulted in a higher RMSE and more virtual collisions than forward driving. RMSE rates were greater in left and right turns than straight and docking tasks.

Conclusions

Testing with instrumented real wheelchairs can validate the virtual driving environment and assess whether virtual driving skills transfer to actual driving.

Key Words: Brain injuries, Rehabilitation, Wheelchairs