POSITION MEASUREMENT SYSTEM, RECEIVER, AND POSITION MEASUREMENT METHOD

摘要

PROBLEM TO BE SOLVED: To provide a position measurement system accurately measuring the position of a tag device without being affected by a measurement environment.SOLUTION: In each of a plurality of receivers 200, a delay time measurement section 250 measures, as delay timeΔTB, time from reference time t0 until first reception time t1 when a first ultrasonic wave reception section 231 receives ultrasonic waves. An ultrasonic wave reception difference time calculation section 240 calculates an ultrasonic wave reception time differenceΔTA that is a temporal difference between the first reception time t1 and second reception time t2 when a second ultrasonic wave reception section 232 receives ultrasonic waves. The second ultrasonic wave reception section 232 is formed into a substantially hemisphere shape so that a distance between the second ultrasonic wave reception section 232 and the first ultrasonic wave reception section 231 is a constant inter-reception-section distance R. An actual sonic speed value calculation section of a host divides the inter-reception-section distance R by the ultrasonic wave reception time differenceΔTA to calculate an actual sonic speed value CR. A position calculation section calculates the position of a tag device on the basis of the actual sonic speed value CR, the delay timeΔTB, and the positions of the plurality of receivers 200.