Abstract: The present invention provides a method of position sensing between a wireless mobile component carrying a mobile ultrasonic transducer and a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising turning off all the transducers to establish a period of silence, activating one or more of the fixed transducers to transmit an ultrasonic signal, starting a plurality of timers corresponding to the respective plurality of fixed transducers generally simultaneously with transmitting the signal, receiving the signal at the mobile transducer, transmitting a signal from the mobile transducer responsive to the received signal, receiving the signal transmitted by the mobile transducer at each fixed transducer and stopping the respective timer generally at the time of reception of an edge of the received signal found within the first twenty received edges and preferably within the first ten received edges and more preferably at the first re

Abstract: A transducer for detecting position in three generally orthogonal directions has a base unit (10), a mobile unit (20) and a hollow elongate arm (6) which is fixed to the base unit and is angularly movable relative to the base unit such that in use it extends generally towards the mobile unit. A variable length coupling line (4) coupling the base unit to the mobile unit passes through the guide arm and thus measurement of the angular position of the guide arm and the extended length of the coupling length of the coupling line enables the relative positions of the base unit and the mobile unit to be calculated. The angle made between the coupling line and the mobile unit may also be measured which allows the position of distal parts of the mobile unit to be determined relative to the base unit.

Abstract: A transducer for detecting position in three generally orthogonal directions has a base unit (10), a mobile unit (20) and a hollow elongate arm (6) which is fixed to the base unit and is angularly movable relative to the base unit such that in use it extends generally towards the mobile unit. A variable length coupling line (4) coupling the base unit to the mobile unit passes through the guide arm and thus measurement of the angular position of the guide arm and the extended length of the coupling length of the coupling line enables the relative positions of the base unit and the mobile unit to be calculated. The angle made between the coupling line and the mobile unit may also be measured which allows the position of distal parts of the mobile unit to be determined relative to the base unit.