An electronic device comprises a processing unit operably coupled to a buffer random access memory, in turn operably coupled to a non-volatile memory configured to emulate an electrically erasable programmable read only memory. The inventive wheelchair is characterized by the fact that the wheelbase is adjustable. The error Kalman filter includes correction for navigation solution, and IMU and GPS parameters. Each accumulator is adapted to render a summary T2 database tag data structure from a set of data values retrieved from the process history database for a specified T1 database tag. The battery and control circuit are completely contained within the integral morcellator such that no separate components are needed. Furthermore, the surgeon has the option of computing and displaying the three-dimensional distance between two points defined by any two trajectories.