| 摘要 |
A positional locating method and apparatus (10) for measuring distances by accurately determining the transit time of ultrasonic wave bursts (22) between two or more points is disclosed. Timer clocks (60), (62), (64) and (66) are started when each of the bursts (22) is triggered to be emitted from a transmission point (14), and are stopped when a highly defined point (56) in the burst (22) is received at a corresponding receiving point (32), (34), (36) and (38). The highly defined point (56) is determined by first analyzing the burst (22) to identify a particular cycle (54) within the burst (22). That particular cycle (54) is then analyzed to detect the specific point (56) within the cycle (54). Use of multiple transmitters (9312), (9314) and (9316) or receivers (932), (934) and (936) permits the calculation of position within two or three physical dimensions using ordinary trigonometric calculations. The inventive method also has sufficient resolution to permit the calculation of attitudinal data by detecting very fine positional differences in a plurality of reference points located at relatively close distances on a movable marker device (912). An input device of the present invention comprises a control means, a transducer means, and a mouse. In a 6D mode of operation, three-dimensional positional information with three degrees of freedom is provided to the computer. |
