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).