Ultrasonic ground speedometer utilizing doppler effect of ultrasonic waves
First Claim
1. An ultrasonic ground speedometer utilizing Doppler effect of ultrasonic waves, comprising:
- ultrasonic transmitting means for outputting an ultrasonic wave at an emitting angle against a road surface;
ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface;
means for deriving a Doppler shift frequency between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means;
first arithmetic means for deriving a first angle difference between said emitting angle and a reception angle defined between the road surface and a propagation direction of the reflected ultrasonic wave received by said ultrasonic receiving means, on the basis of said Doppler shift frequency; and
calculation means for calculating a ground speed of a vehicle mounting said ultrasonic ground speedometer, on the basis of both said Doppler shift frequency and said first angle difference.
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Accused Products
Abstract
An ultrasonic ground speedometer utilizing Doppler effect of ultrasonic waves comprises an ultrasonic transmitter for outputting an ultrasonic wave at an emitting angle against a road surface, an ultrasonic receiver for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface, a signal processor for deriving a Doppler shift frequency between the frequencies of the output ultrasonic wave from the ultrasonic transmitter and the reflected ultrasonic wave received by the ultrasonic receiver, a first arithmetic circuit for deriving the angle difference between the emitting angle and the reception angle defined between the road surface and the propagation direction of the reflected ultrasonic wave received by the receiver, on the basis of the Doppler shift frequency, and a calculating circuit for calculating a ground speed of the vehicle, on the basis of both the Doppler shift frequency and the angle difference.
10 Citations
13 Claims
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1. An ultrasonic ground speedometer utilizing Doppler effect of ultrasonic waves, comprising:
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ultrasonic transmitting means for outputting an ultrasonic wave at an emitting angle against a road surface; ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface; means for deriving a Doppler shift frequency between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means; first arithmetic means for deriving a first angle difference between said emitting angle and a reception angle defined between the road surface and a propagation direction of the reflected ultrasonic wave received by said ultrasonic receiving means, on the basis of said Doppler shift frequency; and calculation means for calculating a ground speed of a vehicle mounting said ultrasonic ground speedometer, on the basis of both said Doppler shift frequency and said first angle difference. - View Dependent Claims (2, 3, 4)
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5. An ultrasonic ground speedometer utilizing Doppler effect of ultrasonic waves, for an automotive vehicle comprising:
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ultrasonic transmitting means for outputting an ultrasonic wave at a preset emitting angle against a road surface, in the vehicle forward direction, said preset emitting angle corresponding to an actual emitting angle obtained in a vehicle stopped state; ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface; means for deriving a Doppler shift frequency between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means; first arithmetic means for deriving a first angle difference between said preset emitting angle and a reception angle defined between the road surface and a propagation direction of the reflected ultrasonic wave received by said ultrasonic receiving means, on the basis of said Doppler shift frequency; and calculation means for calculating a ground speed of the vehicle mounting said ultrasonic ground speedometer, on the basis of both said Doppler shift frequency and said first angle difference. - View Dependent Claims (6, 7)
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8. An ultrasonic ground speedometer utilizing Doppler effect of ultrasonic waves, for an automotive vehicle comprising:
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ultrasonic transmitting means for outputting an ultrasonic wave at a preset emitting angle against a road surface, in the vehicle forward direction, said preset emitting angle corresponding to an actual emitting angle obtained in a vehicle stopped state; ultrasonic receiving means for receiving a reflected ultrasonic wave caused by reflection of the output ultrasonic wave from the road surface; means for deriving a Doppler shift frequency between the frequencies of the output ultrasonic wave from said ultrasonic transmitting means and the reflected ultrasonic wave received by said ultrasonic receiving means; first arithmetic means for deriving a first angle difference between an actual emitting angle and a reception angle defined between the road surface and a propagation direction of the reflected ultrasonic wave received by said ultrasonic receiving means, on the basis of said Doppler shift frequency; second arithmetic means for compensating said actual emitting angle depending on said ground speed, said second arithmetic means compensating said actual emitting angle by a second angle difference between said actual emitting angle obtained in a vehicle running state and a preset emitting angle obtained in a vehicle stopped state, said second arithmetic means deriving said second angle difference, on the basis of said Doppler shift frequency; and calculation means for calculating a ground speed of the vehicle mounting said ultrasonic ground speedometer, on the basis of said Doppler shift frequency, said first angle difference and said second angle difference. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification