ViEW : Virtual Electric Wheelchair Simulator

We created a wheelchair simulator from the ground up, as we could not find an existing tool that provided simple access to simulation data for use in further analysis. The second factor motivating the development was the need for simulators that could be adapted to the context of specific rehabilitation centers (input devices, exercises, features, environment, etc.). Being in complete control of the development made modifications considerably easier, such as adding needed features to the tool. The drawback of this complete freedom lies in the complex engineering necessary for designing and testing the simulator. The ViEW 3D wheelchair simulator has several aims: safe driving training, testing control skills relative to user-specific wheelchair prescriptions, providing aid for parameterizing wheelchair settings, and testing new features. To facilitate the diffusion and experimental use of the simulator in various rehabilitation centers, we focused development on
software only. Consequently, the system is composed of a computer, its screen, and the control device: a modified PW joystick.

To simulate behavior of a real wheelchair as closely as possible, we modeled three different types of wheelchair drive motor systems: front-wheel drive for traction, rearwheel drive for propulsion, and central or mid-wheel drive for holonomic control (maneuverability). But, during this study, only the propulsion architecture has been used. We used a physical model of the wheelchair to take into account gravity and friction for the simulation of real-world motion parameters (inertia, acceleration, etc.), allowing the simulator, for example, to climb a pavement surface. As is the case for real wheelchairs, these movements are generated by torques applied to the driving wheels and directed by joystick control. This joystick was modeled from a real wheelchair joystick, which we modified by replacing the original electronic devices with our own to facilitate connecting it to the simulator.

When a person “drives” using the simulator while seated in their own wheelchair, the real joystick is simply folded out of position and replaced with our modified version. We also augmented the immersive system to allow the user to manage collision scenarios within a 3D environment by displaying an animated prolongation of the user’s arm visible to the user in the virtual environment representing the arm
controlling the wheelchair (left-handed and right-handed visuals are both possible). The significance of adding a visual representation of the body (or a part of the user’s body) in the virtual scene is that it induces user presence; a highly present individual is more likely to behave in a virtual environment as they would behave in similar circumstances in the real world. Finally, we configured the simulator to
display performance measures and parameters of the achieved trajectories: speed, duration, and number of collisions.