초록 ▼

Given a trajectory and unit pointing vectors determined based on a planar or other approximation of a shock wave, a method and apparatus are provided to calculate times the sensors should have detected, based on a conical geometry of the shock wave. A difference between the calculated times and the

Given a trajectory and unit pointing vectors determined based on a planar or other approximation of a shock wave, a method and apparatus are provided to calculate times the sensors should have detected, based on a conical geometry of the shock wave. A difference between the calculated times and the actual times measured by the sensors may be minimized. The minimization may be performed by perturbing the unit vectors. When the perturbation of the unit vectors results in an acceptable difference between the calculated times and the measured times, an accurate trajectory of the projectile can be generated from the perturbed unit pointing vectors.

대표청구항 ▼

Given a trajectory and unit pointing vectors determined based on a planar or other approximation of a shock wave, a method and apparatus are provided to calculate times the sensors should have detected, based on a conical geometry of the shock wave. A difference between the calculated times and the

Given a trajectory and unit pointing vectors determined based on a planar or other approximation of a shock wave, a method and apparatus are provided to calculate times the sensors should have detected, based on a conical geometry of the shock wave. A difference between the calculated times and the actual times measured by the sensors may be minimized. The minimization may be performed by perturbing the unit vectors. When the perturbation of the unit vectors results in an acceptable difference between the calculated times and the measured times, an accurate trajectory of the projectile can be generated from the perturbed unit pointing vectors. y includes emitting a first ultrasonic signal at the first ultrasonic frequency toward the occupant seating position, receiving a first return echo of the first ultrasonic signal, and determining time duration between emission of the first ultrasonic signal and reception of the first return echo, and said step of echo ranging at the second ultrasonic frequency includes emitting a second ultrasonic signal at the second frequency toward the occupant seating position, receiving a second return echo of the second ultrasonic signal, and determining time duration between emission of the second ultrasonic signal and reception of the second return echo. 4. A method as set forth in claim 2, including controlling the emission of the first ultrasonic signal and the emission of the second ultrasonic signal to cause emission of the second ultrasonic signal subsequent to emission of the first ultrasonic signal and prior to reception of the first signal echo and to cause emission of a subsequent first ultrasonic signal subsequent to emission of the second ultrasonic signal and prior to reception of the second signal echo. 5. A method as set forth in claim 2, wherein said step of determining the occupant location characteristic using at least one of the determined distances is associated with one of the first and second frequencies, said method includes monitoring interference at the other of the first and second frequencies. 6. A method as set forth in claim 2, wherein said step of determining the occupant location characteristic includes determining a distance to an occupant as the occupant location characteristic. 7. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising: a sensor having transmitter means and receiver means, said transmitter means for repeatedly transmitting first and second ultrasonic signals, said second ultrasonic signal having a frequency that is different from a frequency of said first ultrasonic signal, said second ultrasonic signal being transmitted at a predetermined time interval after transmission of said first ultrasonic signal, said receiver means for receiving first and second return echoes of the first and second ultrasonic signals, respectively; means for differentiating said first return echo from said second return echo; means for determining a time-of-flight of one of said first and second ultrasonic signals; and means for calculating the vehicle occupant location characteristic using the determined time-of-flight, said transmitter means for emitting the first ultrasonic signal including a transducer operating at a resonant frequency of said transducer, the resonant frequency being the frequency of the first ultrasonic signal, and said transmitter means for emitting the second ultrasonic signal includes said transducer operating at a first harmonic frequency of said transducer, the first harmonic frequency being the frequency of the second ultrasonic signal. 8. An apparatus for determining a vehicle occupant location characteristic, said apparatus comprising: a sensor having transmitter means and receiver means, said transmitter means for repeatedly transmitting first and second ultrasonic signals, said second ultrasonic signal having a frequency that is different from a frequency of said first ultrasonic signal, said second ultrasonic signal being transmitted at a predetermined time interval after transmission of said first ultrasonic signal, said receiver means for receiving first and second return echoes of the first and second ultrasonic signals, respectively; means for differentiating said first return echo from said second return echo; means for determining a time-of-flight of one of said first and second ultrasonic signals; and means for calculating the vehicle occupant location characteristic using the determined time-of-flight, said transmitter means for emitting the first ultrasonic signal including a transducer operating at a first res