US Patent 9163471 Position monitoring system and method

An ultrasonic position sensing system is disclosed. In one embodiment, the system includes an ultrasonic sensor configured to monitor the position of a device. The system also includes ranging logic. The sensor is controlled by the logic to direct an ultrasonic pulse toward the device. The logic is configured to compute the transit time and the velocity of the ultrasonic pulse. Based on these parameters, the logic computes the path length between the sensor and the device, which corresponds to the location of the device relative to the location of the sensor. In further embodiments, the ultrasonic positioning system may include multiple sensors in communication with the ranging logic for monitoring multiple devices.