Abstract: An apparatus for detecting impact using an electronic means and microspheres. A helmet system comprises a helmet adapted to be worn on a user's head. A sensor is mounted on the helmet and is adapted to sense a threshold impact equal to or exceeding a threshold force on the helmet. A circuit is connected to and is responsive to the sensor for indicating that the threshold impact has occurred. The circuit includes a sensing circuit generating an impact signal when the sensing circuit is subjected to an impact equal to or exceeding a threshold impact level. A detector detects the impact signal. An indicator is responsive to the detector for providing an indication that the impact signal has been detected whereby the indication indicates that the sensing circuit has been subjected to an impact equal to or exceeding the threshold impact level.

Abstract: A method and apparatus for determining the position and/or the orientation of a movable object using a Doppler shift of electromagnetic signals. The apparatus includes a transmitter for transmitting a periodic electromagnetic signal, a sensor mountable on the object for receiving the signal transmitted by the transmitter and a controller in communication with the transmitter and the sensor for determining the position and/or orientation of the sensor relative the transmitter.