Dell's Optiplex GX240, Costar Video Systems' CV-M50, and ScanSoft's DragonDictate are components used by researchers at the University of Notre Dame and the Hines Veterans Administration Hospital to develop the Sabre trainable voice-activated wheelchair. The data gathered from ultrasound and visual sensors are used to develop trajectories that the disabled rider can launch on command. Use of a wall-mounted visual reference cures during teaching and tracking events obviate the need for globally accurate mapping. The disabled user activates taught trajectories by choosing the desired destination from an audio menu via an ordinary switch, such as a chin switch, that is compatible with the abilities of the user. The same switch can be used to stop the chair, resume movement, or reverse at any point, including mid-maneuver. Two rotary incremental encoders that are connected to a four-quadrature encoder input board are used to measure wheel rotation of the Sabre power wheelchair, The input board is in an Optiplex GX 240 desktop that runs Windows XP Professional. For digitization of reference images, two CV-M50 cameras from Costar Video are installed below the vehicle seat and connected to a data Translation DT3162 frame-grabber board. The board captures 640x480-pixel monochrome images of video and makes them available to the host PC. The cameras 'see' a series of landmarks or cues attached to the wall in known locations to determine the vehicle's position and orientation. Algorithm development for the Sabre wheelchair system was done in C++ with MS Developer Studio 6.0, the Standard Template Library, and MFC.