A process for controlling the track, speed and direction of a collapsably foldable, central processor unit controlled, electronically motorized, individual drive wheeled, cart assembly system for use by a cart assembly user in a field of play, comprising: arranging a pair of spaced-apart wireless ultrasound transponders (UT1, UT2) on a frame portion of the cart assembly , said pair of spaced-apart wireless ultrasound transponders (UT1, UT2) configured for transmitting ultrasound signals wirelessly; providing a carryable wireless location ultrasound transceiver device (T) to a user of the cart assembly , said carryable wireless location ultrasound transceiver device (T) configured for receiving and sending ultrasound signals (S) wirelessly; wirelessly sending a pair of corresponding ultrasound signals from the pair of spaced-apart wireless ultrasound transponders (UT1, UT2) on the cart assembly to the carryable wireless location transceiver (T) device carried by a user; operating the carryable wireless location ultrasound transceiver device (T) as a remote control to instruct the cart assembly to autonomously advance to a user-desired destination position; characterized in that the process further includes: wirelessly receiving returned back ultrasound signals from the carryable wireless location transceiver (T) device carried by a user; timing the pair of received wireless ultrasound signals received back to the cart assembly by an onboard RF transponder (RF1) using a radio frequency transceiver configured for providing timing for wirelessly received ultrasound signals utilized by a central processing unit computer in the cart assembly ; communicating the signals received by the ultrasound transponder (UT1, UT2) and the RF transponder (RF1) to the central processing unit computer; and triangulating the signals so as to govern the electronic instructions to the individual drive wheels as to both their individual direction of rotation and their individual speed of rotation for the cart assembly to follow the user's instructions carrying the transceiver device (T). arranging a pair of spaced-apart wireless ultrasound transponders (UT1, UT2) on a frame portion of the cart assembly , said pair of spaced-apart wireless ultrasound transponders (UT1, UT2) configured for transmitting ultrasound signals wirelessly; providing a carryable wireless location ultrasound transceiver device (T) to a user of the cart assembly , said carryable wireless location ultrasound transceiver device (T) configured for receiving and sending ultrasound signals (S) wirelessly; wirelessly sending a pair of corresponding ultrasound signals from the pair of spaced-apart wireless ultrasound transponders (UT1, UT2) on the cart assembly to the carryable wireless location transceiver (T) device carried by a user; operating the carryable wireless location ultrasound transceiver device (T) as a remote control to instruct the cart assembly to autonomously advance to a user-desired destination position; wirelessly receiving returned back ultrasound signals from the carryable wireless location transceiver (T) device carried by a user; timing the pair of received wireless ultrasound signals received back to the cart assembly by an onboard RF transponder (RF1) using a radio frequency transceiver configured for providing timing for wirelessly received ultrasound signals utilized by a central processing unit computer in the cart assembly ; communicating the signals received by the ultrasound transponder (UT1, UT2) and the RF transponder (RF1) to the central processing unit computer; and triangulating the signals so as to govern the electronic instructions to the individual drive wheels as to both their individual direction of rotation and their individual speed of rotation for the cart assembly to follow the user's instructions carrying the transceiver device (T). <EOS>